Science.gov

Sample records for butyl radicals

  1. Butylate

    Integrated Risk Information System (IRIS)

    Butylate ; CASRN 2008 - 41 - 5 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effects

  2. ATOM TRANSFER RADICAL POLYMERIZATION OF N-BUTYL METHACRYLATE IN AQUEOUS DISPERSED SYSTEMS: A MINIEMULSION APPROACH. (R826735)

    EPA Science Inventory

    Ultrasonication was applied in combination with a hydrophobe for the copper-mediated atom transfer radical polymerization of n-butyl methacrylate in an aqueous dispersed system. A controlled polymerization was successfully achieved, as demonstrated by a linear correlation between...

  3. Changes in oxygen consumption induced by t-butyl hydroperoxide in perfused rat liver. Effect of free-radical scavengers.

    PubMed Central

    Videla, L A; Villena, M I; Donoso, G; Giulivi, C; Boveris, A

    1984-01-01

    The addition of t-butyl hydroperoxide to perfused rat liver elicited a biphasic effect on hepatic respiration. A rapid fall in liver oxygen consumption was initially observed, followed by a recovery phase leading to respiratory rates higher than the initial steady-state values of oxygen uptake. This overshoot in hepatic oxygen uptake was abolished by free-radical scavengers such as (+)-cyanidanol-3 or butylated hydroxyanisole at concentrations that did not alter mitochondrial respiration. (+)-Cyanidanol-3 was also able to facilitate the recovery of respiration, the diminution in the calculated rate of hydroperoxide utilization and the decrease in liver GSH content produced by two consecutive pulses of t-butyl hydroperoxide. It is suggested that the t-butyl hydroperoxide-induced overshoot in liver respiration is related to increased utilization of oxygen for lipid peroxidation as a consequence of free radicals produced in the scission of the hydroperoxide by cellular haemoproteins. PMID:6508746

  4. Absolute rate constants of alkoxyl radical reactions in aqueous solution. [Tert-butyl hydroperoxide

    SciTech Connect

    Erben-Russ, M.; Michel, C.; Bors, W.; Saran, M.

    1987-04-23

    The pulse radiolysis technique was used to generate the alkoxyl radical derived from tert-butyl hydroperoxide (/sup t/BuOOH) in aqueous solution. The reactions of this radical with 2,2'-azinobis(3-ethyl-6-benzothiazolinesulfonate) (ABTS) and promethazine were monitored by kinetic spectroscopy. The unimolecular decay rate constant of the tert-butoxyl radical (/sup t/BuO) was determined to be 1.4 x 10/sup 6/ s/sup -1/. On the basis of this value, the rate constants for /sup t/BuO attack on quercetin, crocin, crocetin, ascorbate, isoascorbate, trolox c, glutathione, thymidine, adenosine, guanosine, and unsaturated fatty acids were determined. In addition, the reaction of /sup t/BuO with the polyunsaturated fatty acids (PUFA) was observed by directly monitoring the formation of the fatty acid pentadienyl radicals. Interestingly, the attack of /sup t/BuO on PUFA was found to be faster by about one order of magnitude as compared to the same reaction in a nonpolar solvent.

  5. Quantum mechanical investigation on bimolecular hydrogen abstractions in butyl acrylate-based free radical polymerization processes.

    PubMed

    Mavroudakis, Evangelos; Cuccato, Danilo; Moscatelli, Davide

    2014-03-13

    The present computational study focuses on the investigation of bimolecular hydrogen abstractions that can occur during free radical polymerization (FRP) processes. In particular, several hydrogen abstractions from four monomers (butyl acrylate, BA; styrene, ST; butyl methacrylate, BMA; vinyl acetate, VA) and three different backbone chains (poly-BA, poly-BA-co-VA, and poly-BA-co-ST) have been studied. The aim is to provide an overview of the kinetics for all possible intermolecular hydrogen abstraction reactions from all chemical species present in a bulk FRP as well as to support the understanding of the influence of chemical environment on hydrogen abstractions. All simulations were performed using density functional theory (DFT) with quantum tunneling factors estimated using the Eckart model. This study provides proof that the presence of an electron donating group in the chemical environment of the abstracted hydrogen atoms can lead to lower activation energies and higher rate coefficients for abstraction whereas the presence of an electron withdrawing group leads to opposite effects. PMID:24555565

  6. PRODUCTS OF THE GAS-PHASE REACTIONS OF THE OH RADICAL WITH N-BUTYL METHYL ETHER AND 2-ISOPROPOXYETHANOL: REACTIONS OF ROC(O)< RADICALS. (R825252)

    EPA Science Inventory

    The products of the gas-phase reactions of the OH radical with n-butyl methyl ether and 2-isopropoxyethanol in the presence of NO have been investigated at 298 ? 2 K and 740 Torr total pressure of air by gas chromatography and in situ atmospheric pressure ionization...

  7. PREPARATION OF BLOCK COPOLYMERS OF POLY(STYRENE) AND POLY(T-BUTYL ACRYLATE) OF VARIOUS MOLECULAR WEIGHTS AND ARCHITECTURES BY ATOM TRANSFER RADICAL POLYMERIZATION. (R826735)

    EPA Science Inventory

    Block copolymers of polystyrene and poly(t-butyl acrylate) were prepared using atom transfer radical polymerization techniques. These polymers were synthesized with a CuBr/N,N,N,NAllylic Oxidations Catalyzed by Dirhodium Caprolactamate via Aqueous tert-Butyl Hydroperoxide: The Role of the tert-Butylperoxy Radical

    PubMed Central

    McLaughlin, Emily C.; Choi, Hojae; Wang, Kan; Chiou, Grace; Doyle, Michael P.

    2009-01-01

    Dirhodium(II) caprolactamate exhibits optimal efficiency for the production of the tert-butylperoxy radical, which is a selective reagent for hydrogen atom abstraction. These oxidation reactions occur with aqueous tert-butyl hydroperoxide (TBHP) without rapid hydrolysis of the caprolactamate ligands on dirhodium. Allylic oxidations of enones yield the corresponding enedione in moderate to high yields, and applications include allylic oxidations of steroidal enones. Although methylene oxidation to a ketone is more effective, methyl oxidation to a carboxylic acid can also be achieved. The superior efficiency of dirhodium(II) caprolactamate as a catalyst for allylic oxidations by TBHP (mol % catalyst, % conversion) is described in comparative studies with other metal catalysts that are also reported to be effective for allylic oxidations. That different catalysts produce essentially the same mixture of products with the same relative yields suggests that the catalyst is not involved in product forming steps. Mechanistic implications arising from studies of allylic oxidation with enones provide new insights into factors that control product formation. A previously undisclosed disproportionation pathway, catalyzed by the tert-butoxy radical, of mixed peroxides for the formation of ketone products via allylic oxidation has been uncovered. PMID:19072696

  8. Reaction of carboranyl boron-centered radicals with phosphites and the addition of carborane-containing and some other phosphoranyl radicals to 3,6-di-tert-butyl-ortho-benzoquinone

    SciTech Connect

    Tumanskii, B.L.; Kampel', V.Ts.; Bregadze, VI.; Bubnov, N.N.; Solodovnikov, S.P.; Prokof'ev, A.I.; Kozlov, E.S.; Godovikov, N.N.; Kabachnik, M.I.

    1986-08-20

    The preparative photolysis of bis(m-carboran-9-yl)mercury and bis(p-carboran-2-yl)-mercury with trimethyl phosphite leads to the dimethyl esters of m- and p-B-carboranylphosphonic acids. The reaction of carboranyl boron-centered radicals with phosphites occurs through the formation of a phosphoranyl radical. The addition of the phosphoranyl radicals derived from 2,6,7-tris(trichloromethyl)-3,5,8-trioxo-1,4-diphosphabicyclo(2.2.2)octane to 3,6-di-tert-butyl-ortho-benzoquinone was detected. ESR spectroscopy was used to observe the tautomeric transfers of the phosphoranyl group between the ortho-benzoquinone oxygen atoms.

  9. Electron paramagnetic resonance study of free radicals in γ-irradiated L-glutamine and L-glutamine-t-butyl ester hydrochloride

    NASA Astrophysics Data System (ADS)

    Yeşim Dicle, Işık; Osmanğolu, Şemsettin; İpek, Nazenin

    2015-01-01

    Electron paramagnetic resonance (EPR) spectra of γ-irradiated single crystals of l-glutamine (LG) and l-glutamine-t-butyl ester hydrochloride (LGBESHCI) powders were studied and analyzed for different orientations of the crystals in the magnetic field, after γ-irradiation. The spectra were observed to be independent of temperature down to 130 K. The hyperfine interaction tensors for one α proton and two β protons of radical have been determined at 295 K. An analysis of the EPR of γ-irradiated single crystals of LG and LGBESHCI powders shows that the paramagnetic species produced by the radiation damage is CH2ĊH. The g values of the radical and the hyperfine structure constants of the free electron with nearby protons and 14N nucleus were determined. The results were found to be in good agreement with the existing literature data.

  10. RATE CONSTANTS FOR THE REACTIONS OF OH RADICALS AND CL ATOMS WITH DI-N-PROPYL ETHER AND DI-N-BUTYL ETHER AND THEIR DEUTERATED ANALOGS. (R825252)

    EPA Science Inventory

    Using relative rate methods, rate constants for the gas-phase reactions of OH radicals and Cl atoms with di-n-propyl ether, di-n-propyl ether-d14, di-n-butyl ether and di-n-butyl ether-d18 have been measured at 296 ? 2 K and atmos...

  11. Controlled/Living Radical Polymerization in the Undergraduate Laboratories. 1. Using ATRP to Prepare Block and Statistical Copolymers of n-Butyl Acrylate and Styrene

    NASA Astrophysics Data System (ADS)

    Beers, Kathryn L.; Woodworth, Brian; Matyjaszewski, Krzysztof

    2001-04-01

    A simple method of preparing well-defined (co)polymers has been developed for application in an advanced undergraduate laboratory. The method utilizes atom transfer radical polymerization (ATRP), a controlled/living radical polymerization, to prepare difunctional poly(n-butyl acrylate) with bromine end groups, which is chain-extended with styrene to yield an ABA triblock copolymer. Simultaneously, a statistical copolymer of the two monomers is prepared for comparison. The two copolymers are isolated and compositions and molecular weights are determined using 1H NMR and SEC, respectively. Optional additions to the experiment include performing a kinetic analysis of the homopolymerization using GC and SEC, and possibly comparing the results to those expected for conventional radical polymerization. Material differences in the copolymers can be observed qualitatively or measured using thermal or mechanical analysis. The lab is designed in such a way that several parts of the whole can be used to emphasize different areas of polymer science. A more synthetic course such as the organic synthesis lab can opt to investigate only the kinetic and composition analyses, whereas an engineering or materials science course may pursue more rigorous analysis of the materials' properties. Results included here are intended for application in an organic synthesis laboratory course.

  12. Generation and loss of radicals from the decomposition of methyl iodide, diallyl, and butyl halides on a silver catalyst

    SciTech Connect

    Garibyan, T.A.; Grigoryan, R.R.; Muradyan, A.A.; Nalbandyan, A.B.

    1987-12-01

    The stages of the generation and loss of CH/sub 3/O/sub 2/, C/sub 3/H/sub 5/O/sub 2/, and C/sub 4/H/sub 9/O/sub 2/ radicals in the decomposition of CH/sub 3/I, (C/sub 3/H/sub 5/)/sub 2/, C/sub 4/H/sub 9/Br, C/sub 4/H/sub 9/Cl, and C/sub 4/H/sub 9/I, respectively, have been studied in the presence of oxygen on Ag/pumice. Effective energies of activation for generation of these radicals have been calculated. It has been found that heterogeneously catalyzed decomposition of these compounds begins on the silver surface at low temperatures (400-590 K) and is accompanied by desorption of the radicals from the surface of the catalyst to the gas phase. It has also been demonstrated that in the indicated temperature range on the silver catalyst allyl peroxy radicals are stable, bu that the CH/sub 3/O/sub 2/ and C/sub 4/H/sub 9/O/sub 2/ radicals disappear to a small extent (10 and 23%, respectively).

  13. Free radical scavenging abilities of flavonoids as mechanism of protection against mutagenicity induced by tert-butyl hydroperoxide or cumene hydroperoxide in Salmonella typhimurium TA102.

    PubMed

    Edenharder, R; Grünhage, D

    2003-09-01

    Mutagenicity induced by tert-butyl hydroperoxide (BHP) or cumene hydroperoxide (CHP) in Salmonella typhimurium TA102 was effectively reduced by flavonols with 3',4'-hydroxyl groups such as fisetin, quercetin, rutin, isoquercitrin, hyperoxide, myricetin, myricitrin, robinetin, and to a lesser extent also by morin and kaempferol (ID50=0.25-1.05 micromol per plate). With the exception of isorhamnetin, rhamnetin, morin, and kaempferol, closely similar results were obtained with both peroxides. Hydrogenation of the double bond between carbons 2 and 3 (dihydroquercetin, dihydrorobinetin) as well as the additional elimination of the carbonyl function at carbon 4 (catechins) resulted in a loss of antimutagenicity with the notable exception of catechin itself. Again, all flavones and flavanones tested were inactive except luteolin, luteolin-7-glucoside, diosmetin, and naringenin. The typical radical scavenger butylated hydroxytoluene also showed strong antimutagenicity against CHP (ID50=5.4 micromol per plate) and BHP (ID50=11.4 micromol per plate). Other lipophilic scavengers such as alpha-tocopherol and N,N'-diphenyl-1,4-phenylenediamine exerted only moderate effects, the hydrophilic scavenger trolox was inactive. The metal chelating agent 1,10-phenanthroline strongly reduced mutagenicities induced by CHP and BHP (ID50=2.75 and 2.5 micromol per plate) at low concentrations but induced mutagenic activities at higher concentrations. The iron chelator deferoxamine mesylate, however, was less effective in both respects. The copper chelator neocuproine effectively inhibited mutagenicity induced by BHP (ID50=39.7 micromol per plate) and CHP (ID50=25.9 micrommol per plate), the iron chelator 2,2'-dipyridyl was less potent (ID50=6.25 mmol per plate against BHP, 0.42 mmol per plate against CHP). In the absence of BHP and CHP, yet not in the presence of these hydroperoxides, quercetin, rutin, catechin, epicatechin, and naringenin induced strong mutagenic activities in S

  14. Transition-metal-free oxychlorination of alkenyl oximes: in situ generated radicals with tert-butyl nitrite.

    PubMed

    Zhang, Xiao-Wei; Xiao, Zu-Feng; Wang, Mei-Mei; Zhuang, Yan-Jun; Kang, Yan-Biao

    2016-07-26

    Oxychlorination of alkenyl oximes is harder compared to the analogous oxybromination or oxyiodination because of the difficulty associated with the formation of chlorine cations or radicals. A transition-metal-free oxychlorination of alkenyl oximes has been developed, using t-BuONO as a dual oxidant and AlCl3 as a chlorine source. This convenient and practical method has been used to construct chloroisoxazolines in moderate to good yields, whereas N-chlorosuccinimide (NCS) failed to promote this reaction. PMID:27391419

  15. Protection against oxidative damage to CNS by alpha-phenyl-tert-butyl nitrone (PBN) and other spin-trapping agents: A novel series of nonlipid free radical scavengers

    SciTech Connect

    Carney, J.M.; Floyd, R.A. )

    1991-01-01

    Brain is extremely susceptible to oxidative damage. Utilizing a series of novel approaches, the authors have demonstrated that oxidative damage occurs during an ischemia/reperfusion insult (IRI) to brain. Thus, they have demonstrated that an IRI to Mongolian gerbil brain results in: (1) an enhanced rate of salicylate hydroxylation, implicating an increased flux of hydroxyl free radicals; (2) an enhanced flux of free radicals as determined by spin-trapping; (3) an enhanced level of endogenous protein oxidation; (4) a decrease in glutamine synthetase (GS) activity, an enzyme very sensitive to oxidative damage; and (5) demonstration of protection from an IRI by administering the spin-trapping agent alpha-phenyl-tert-butyl nitrone (PBN). The novel observation that PBN offers protection from the lethality brought on by a brain IRI appears to be clearly linked to the ability of the administered spin-trap to inhibit oxidative damage as evidenced by the decreased amount of brain protein oxidation and the prevention of an IRI-mediated loss of GS activity in treated animals. Aged gerbils are more sensitive to the lethal action of a brain IRI than younger animals, but they are protected by PBN administration as are the younger animals. Older gerbils have a significantly higher level of oxidized protein in the brain. Older gerbils have decreased activities of GS and neutral protease, the enzyme that removes oxidized protein, than younger animals. Chronic twice daily administration of PBN (32 mg/kg) for 14 days to older animals significantly lowered brain oxidized protein levels and raised GS and neutral protease activity to those observed in younger animals. Cessation of PBN administration resulted in a time-dependent restoration of protein oxidation levels and enzyme activities back to those observed prior to spin-trap administration.

  16. Controlled/Living Radical Polymerization in the Undergraduate Laboratories. 2. Using ATRP in Limited Amounts of Air to Prepare Block and Statistical Copolymers of n-Butyl Acrylate and Styrene

    NASA Astrophysics Data System (ADS)

    Matyjaszewski, Krzysztof; Beers, Kathryn L.; Woodworth, Brian; Metzner, Zachary

    2001-04-01

    Developments in controlled radical polymerization have facilitated the use of living polymer chemistry in the undergraduate laboratories. In the first paper of this series, a procedure for the use of atom transfer radical polymerization (ATRP) to prepare block and statistical copolymers was described and the use of kinetic analysis to differentiate between living and conventional processes was demonstrated. In this paper, the experiment is extended to polymerizations run in limited amounts of air so that the use of inert gases is unnecessary. The Cu(I) catalyst can be lost owing to oxidation or termination reactions; however, a scavenger, Cu(0), is added to react with oxidized catalyst to regenerate the Cu(I) complex. A difunctional macroinitiator of poly(n-butyl acrylate) is prepared and chain-extended with polystyrene. A statistical copolymer using the same monomer pair is also prepared. These copolymers are isolated and characterized along with the homopolymeric macroinitiator using 1H NMR and SEC. Kinetic analysis is also carried out using GC and SEC. The significant difference in these two approaches, in addition to slight variations in the reaction conditions, is apparent in the chain extension to yield the ABA triblock copolymer.

  17. Emulsion Polymerization of Butyl Acrylate: Spin Trapping and EPR Study

    NASA Technical Reports Server (NTRS)

    Kim, S.; Westmoreland, D.

    1994-01-01

    The propagating radical in the emulsion polymerization reaction of butyl acrylate was detected by Electron Paramagnetic Resonance spectroscopy using two spin trapping agents, 2-methyl-2nitrosopropane and alpha -N-tert-butylnitrone.

  18. Radical prostatectomy

    MedlinePlus

    Prostatectomy - radical; Radical retropubic prostatectomy; Radical perineal prostatectomy; Laparoscopic radical prostatectomy; LRP; Robotic-assisted laparoscopic prostatectomy; RALP; Pelvic lymphadenectomy; ...

  19. Butyl benzyl phthalate

    Integrated Risk Information System (IRIS)

    Butyl benzyl phthalate ; CASRN 85 - 68 - 7 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinog

  1. Automatic mechanism generation for pyrolysis of di-tert-butyl sulfide.

    PubMed

    Class, Caleb A; Liu, Mengjie; Vandeputte, Aäron G; Green, William H

    2016-08-01

    The automated Reaction Mechanism Generator (RMG), using rate parameters derived from ab initio CCSD(T) calculations, is used to build reaction networks for the thermal decomposition of di-tert-butyl sulfide. Simulation results were compared with data from pyrolysis experiments with and without the addition of a cyclohexene inhibitor. Purely free-radical chemistry did not properly explain the reactivity of di-tert-butyl sulfide, as the previous experimental work showed that the sulfide decomposed via first-order kinetics in the presence and absence of the radical inhibitor. The concerted unimolecular decomposition of di-tert-butyl sulfide to form isobutene and tert-butyl thiol was found to be a key reaction in both cases, as it explained the first-order sulfide decomposition. The computer-generated kinetic model predictions quantitatively match most of the experimental data, but the model is apparently missing pathways for radical-induced decomposition of thiols to form elemental sulfur. Cyclohexene has a significant effect on the composition of the radical pool, and this led to dramatic changes in the resulting product distribution. PMID:27431650

  2. Direct generation of oxygen-stabilized radicals by H• transfer from transition metal hydrides.

    PubMed

    Kuo, Jonathan L; Hartung, John; Han, Arthur; Norton, Jack R

    2015-01-28

    Transition-metal hydrides generate α-alkoxy radicals by H• transfer to enol ethers. We have measured the rate constant for transfer from CpCr(CO)3H to n-butyl vinyl ether and have examined the chemistry of radicals generated by such transfers. Radicals from appropriate substrates undergo 5-exo cyclization, with higher diastereoselectivity than the analogous all-carbon radicals. From such radicals it is straightforward to make substituted tetrahydrofurans. PMID:25569214

  3. 21 CFR 182.3173 - Butylated hydroxytoluene.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Butylated hydroxytoluene. 182.3173 Section 182.3173 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD....3173 Butylated hydroxytoluene. (a) Product. Butylated hydroxytoluene. (b) Tolerance. This substance...

  4. 21 CFR 582.3173 - Butylated hydroxytoluene.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Butylated hydroxytoluene. 582.3173 Section 582.3173 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... § 582.3173 Butylated hydroxytoluene. (a) Product. Butylated hydroxytol- uene. (b) Tolerance....

  5. Sprayed Coating Renews Butyl Rubber

    NASA Technical Reports Server (NTRS)

    Martin, R. B.

    1982-01-01

    Damaged butyl rubber products are renewed by spray technique originally developed for protective suits worn by NASA workers. A commercial two-part adhesive is mixed with Freon-113 (or equivalent) trichlorotrifluoroethane to obtain optimum viscosity for spraying. Mix is applied with an external-air-mix spray gun.

  6. Mechanistic insights into light-driven graphene-induced peroxide decomposition: radical generation and disproportionation.

    PubMed

    Chu, Ya-Lan; Chen, Yen-An; Li, Wei-Chin; Chu, Jean-Ho; Chen, Chun-Hu; Chiang, Chao-Ming

    2016-07-28

    Interaction between adsorbed t-butyl peroxybenzoate and photoexcited graphene rendered trapped phenyl and t-butoxy radicals. Post-irradiation thermal desorption showed benzene, t-butanol, and isobutylene oxide as the end products. The required hydrogen atoms were obtained via the radical disproportionation. Graphene enabled radical species to be captured and their on-surface chemistry to be revealed. PMID:27366795

  7. The photodissociation dynamics of alkyl radicals

    NASA Astrophysics Data System (ADS)

    Giegerich, Jens; Fischer, Ingo

    2015-01-01

    The photodisscociation dynamics of the alkyl radicals i-propyl (CH(CH3)2) and t-butyl (C(CH3)3) are investigated by H-atom photofragment imaging. While i-propyl is excited at 250 nm, the photodynamics of t-butyl are explored over a large energy range using excitation wavelengths between 347 nm and 233 nm. The results are compared to those obtained previously for ethyl, CH3CH2, and to those reported for t-butyl using 248 nm excitation. The translational energy (ET) distribution of the H-atom photofragments is bimodal and appears rather similar for all three radicals. The low ET part of the distribution shows an isotropic photofragment angular distribution, while the high ET part is associated with a considerable anisotropy. Thus, for t-butyl, two H-atom loss channels of roughly equal importance have been identified in addition to the CH3-loss channel reported previously. A mechanism for the photodissociation of alkyl radicals is suggested that is based on interactions between Rydberg- and valence states.

  8. The photodissociation dynamics of alkyl radicals

    SciTech Connect

    Giegerich, Jens; Fischer, Ingo

    2015-01-28

    The photodisscociation dynamics of the alkyl radicals i-propyl (CH(CH{sub 3}){sub 2}) and t-butyl (C(CH{sub 3}){sub 3}) are investigated by H-atom photofragment imaging. While i-propyl is excited at 250 nm, the photodynamics of t-butyl are explored over a large energy range using excitation wavelengths between 347 nm and 233 nm. The results are compared to those obtained previously for ethyl, CH{sub 3}CH{sub 2}, and to those reported for t-butyl using 248 nm excitation. The translational energy (E{sub T}) distribution of the H-atom photofragments is bimodal and appears rather similar for all three radicals. The low E{sub T} part of the distribution shows an isotropic photofragment angular distribution, while the high E{sub T} part is associated with a considerable anisotropy. Thus, for t-butyl, two H-atom loss channels of roughly equal importance have been identified in addition to the CH{sub 3}-loss channel reported previously. A mechanism for the photodissociation of alkyl radicals is suggested that is based on interactions between Rydberg- and valence states.

  9. Effect of xenobiotics on the respiratory activity of rat heart mitochondria and the concomitant formation of superoxide radicals

    SciTech Connect

    Stolze, K.; Nohl, H. . Inst. of Pharmacology and Toxicology)

    1994-03-01

    The effects of the xenobiotics atrazine, benzene, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), lindane, toluene, and xylenol on the respiration of isolated rate heart mitochondria were studied. Bioenergetic parameters such as respiratory control (RC) and ATP/oxygen (P/O) values decreased considerably in the presence of these substances, and a concomitant increase of superoxide radical (O[sub 2][sup [minus

  10. 21 CFR 582.3169 - Butylated hydroxyanisole.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Butylated hydroxyanisole. 582.3169 Section 582.3169 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Chemical Preservatives § 582.3169 Butylated hydroxyanisole....

  11. Radical Hysterectomy

    MedlinePlus

    ... the base of her partner’s penis during intercourse. Orgasm after radical hysterectomy Women who have had a ... the surgery will affect their ability to have orgasms. This has not been studied a great deal, ...

  12. Radical-initiated reaction of methyl linoleate with dialkyl phosphites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The addition of dialkyl phosphite (methyl, ethyl and n-butyl) to methyl linoleate (MeLin) double bonds was investigated. The reaction proved to be more challenging than the analogous reaction with methyl oleate (MeOl), due to inhibition of the radical reaction by the bis-allylic hydrogens of MeLin a...

  13. RAPID MEASUREMENT OF AQUEOUS HYDROXYL RADICAL CONCENTRATIONS IN STEADY-STATE HO· FLUX SYSTEMS

    EPA Science Inventory

    The spin-trap compound a-(4-pyridyl-1-oxide)-N-tert-butyl-nitrone (4-POBN) is utilized for the detection and quantitation of the hydroxyl radical (HO·) in aqueous solution. Capillary electrophoresis enables rapid analysis of the probe compound. The thermally unstable HO· radical ...

  14. Specialty polymeric membranes. 8: Separation of benzene from benzene/cyclohexane mixtures with nylon 6-graft-poly(butyl methacrylate) membranes

    SciTech Connect

    Yoshikawa, Masakazu; Tsubouchi, Keisuke; Kitao, Toshio

    1999-02-01

    A novel pervaporation membrane was prepared by radical graft polymerization of butyl methacrylate onto nylon 6. The permselectivity toward benzene was increased by the introduction of poly(butyl methacrylate) onto a nylon 6 membrane. From pervaporation and sorption experiments, it was shown that the introduction of poly(butyl methacrylate) onto a nylon 6 membrane leads to the enhancement of permselectivity toward benzene. The solubility data for benzene were described by a combination of simple sorption and specific sorption, while cyclohexane solubility was described by simple sorption.

  15. Radiostability of butylated hydroxytoluene (BHT): An ESR study

    NASA Astrophysics Data System (ADS)

    Tuner, H.; Korkmaz, M.

    2007-05-01

    In the present work, the effects of gamma radiation on solid butylated hydroxytoluene (BHT), which is used as an antioxidant, were investigated by ESR spectroscopy. While unirradiated BHT presented no ESR signal, irradiated BHT exhibited an ESR spectrum with many resonance maxima and minima spread over a magnetic field range of 12 mT and centered at about g = 2.0026. Weak satellite and central intense resonance lines, likely, originated from radical species of different stabilities and ratios were observed to be responsible from experimental ESR spectrum of gamma irradiated BHT. Studies based on the variations of the observed line intensities and spectrum area under different experimental conditions were carried out and characteristic features of the radical species responsible from experimental ESR spectrum were determined. Mesomeric radical species of different stabilities providing to BHT a G value of 0.25 were believed to be induced in gamma irradiated BHT. While species responsible from weak satellite lines were unstable, the species causing central intense lines were found to be relatively stable. BHT belongs to a class of compounds with low radiosensitivity ( G = 0.25). This feature of BHT enables the feasibility of radiosterilizations of the products containing BHT as antioxidant without very much loss from its antioxidant benefit. BHT has been shown to provide an opportunity in the estimation of applied radiation dose with a reasonable accuracy if an appropriate mathematical function is used to describe experimental dose-response data.

  16. Electron-impact ionization of benzoic acid, nicotinic acid and their n-butyl esters

    NASA Astrophysics Data System (ADS)

    Opitz, Joachim

    2007-08-01

    Electron-impact ionization mass spectra, the decay of metastable ions, ionization and appearance energies and bond energies, as dissociation energies, are reported for the title compounds. An ionization energy of 9.47 eV was obtained for benzoic acid, 9.43 eV for benzoic acid n-butyl ester, 9.61 eV for nicotinic acid and 9.97 eV for nicotinic acid n-butyl ester. Molecular ions of both butyl esters show two common main fragmentation pathways: the first process is a McLafferty rearrangement, characterized by the transfer of one H-atom from the aliphatic ester chain, which leads to the ions of either the organic acid or 1-butene. From their appearance energies and known thermodynamic data, gas-phase formation enthalpies () of the parent n-butyl esters are calculated. Values of for benzoic acid n-butyl ester and for nicotinic acid n-butyl ester were obtained. The second process is characterized by the transfer of two H-atoms from the ester chain leading to a protonated form of the corresponding organic acids and C4H7 radicals. Good evidence is provided for the formation of methylallyl radicals. Appearance energies are used to calculate a proton affinity (PA) for benzoic acid. The obtained value of PA = (8.73 ± 0.3) eV, corresponding to a protonation of the carbonyl group, is in close corroboration with published data (PA = 8.51 eV). Activation energies for the intermediate H-transfers were found to be insignificant. This methodic gateway is applied to the system of nicotinic acid and its butyl ester. Adopting the formation of a methylallyl radical, the obtained proton affinity of nicotinic acid, PA = 8.58 eV, is very near to the published data of benzoic acid. An alternative fragmentation mechanism leading to a value of PA [approximate] 9.5 eV (typical for a protonation of the pyridine-nitrogen) is very unlikely. It is concluded that this transfer of two H-atoms from the ester chain is controlled by a charge switching between the carboxylic oxygen atoms which leads to

  17. Radicalization and Radical Catalysis of Biomass Sugars: Insights from First-principles Studies

    NASA Astrophysics Data System (ADS)

    Yang, Gang; Zhu, Chang; Zou, Xianli; Zhou, Lijun

    2016-07-01

    Ab initio and density functional calculations are conducted to investigate the radicalization processes and radical catalysis of biomass sugars. Structural alterations due to radicalization generally focus on the radicalized sites, and radicalization affects H-bonds in D-fructofuranose more than in D-glucopyranose, potentially with outcome of new H-bonds. Performances of different functionals and basis sets are evaluated for all radicalization processes, and enthalpy changes and Gibbs free energies for these processes are presented with high accuracy, which can be referenced for subsequent experimental and theoretical studies. It shows that radicalization can be utilized for direct transformation of biomass sugars, and for each sugar, C rather than O sites are always preferred for radicalization, thus suggesting the possibility to activate C-H bonds of biomass sugars. Radical catalysis is further combined with Brønsted acids, and it clearly states that functionalization fundamentally regulates the catalytic effects of biomass sugars. In presence of explicit water molecules, functionalization significantly affects the activation barriers and reaction energies of protonation rather than dehydration steps. Tertiary butyl and phenyl groups with large steric hindrances or hydroxyl and amino groups resulting in high stabilities for protonation products drive the protonation steps to occur facilely at ambient conditions.

  18. Radicalization and Radical Catalysis of Biomass Sugars: Insights from First-principles Studies.

    PubMed

    Yang, Gang; Zhu, Chang; Zou, Xianli; Zhou, Lijun

    2016-01-01

    Ab initio and density functional calculations are conducted to investigate the radicalization processes and radical catalysis of biomass sugars. Structural alterations due to radicalization generally focus on the radicalized sites, and radicalization affects H-bonds in D-fructofuranose more than in D-glucopyranose, potentially with outcome of new H-bonds. Performances of different functionals and basis sets are evaluated for all radicalization processes, and enthalpy changes and Gibbs free energies for these processes are presented with high accuracy, which can be referenced for subsequent experimental and theoretical studies. It shows that radicalization can be utilized for direct transformation of biomass sugars, and for each sugar, C rather than O sites are always preferred for radicalization, thus suggesting the possibility to activate C-H bonds of biomass sugars. Radical catalysis is further combined with Brønsted acids, and it clearly states that functionalization fundamentally regulates the catalytic effects of biomass sugars. In presence of explicit water molecules, functionalization significantly affects the activation barriers and reaction energies of protonation rather than dehydration steps. Tertiary butyl and phenyl groups with large steric hindrances or hydroxyl and amino groups resulting in high stabilities for protonation products drive the protonation steps to occur facilely at ambient conditions. PMID:27405843

  19. Radicalization and Radical Catalysis of Biomass Sugars: Insights from First-principles Studies

    PubMed Central

    Yang, Gang; Zhu, Chang; Zou, Xianli; Zhou, Lijun

    2016-01-01

    Ab initio and density functional calculations are conducted to investigate the radicalization processes and radical catalysis of biomass sugars. Structural alterations due to radicalization generally focus on the radicalized sites, and radicalization affects H-bonds in D-fructofuranose more than in D-glucopyranose, potentially with outcome of new H-bonds. Performances of different functionals and basis sets are evaluated for all radicalization processes, and enthalpy changes and Gibbs free energies for these processes are presented with high accuracy, which can be referenced for subsequent experimental and theoretical studies. It shows that radicalization can be utilized for direct transformation of biomass sugars, and for each sugar, C rather than O sites are always preferred for radicalization, thus suggesting the possibility to activate C-H bonds of biomass sugars. Radical catalysis is further combined with Brønsted acids, and it clearly states that functionalization fundamentally regulates the catalytic effects of biomass sugars. In presence of explicit water molecules, functionalization significantly affects the activation barriers and reaction energies of protonation rather than dehydration steps. Tertiary butyl and phenyl groups with large steric hindrances or hydroxyl and amino groups resulting in high stabilities for protonation products drive the protonation steps to occur facilely at ambient conditions. PMID:27405843

  20. tert-butyl-substituted cyclooctatetraenes

    SciTech Connect

    Miller, M.J.; Lyttle, M.H.; Streitwieser, A. Jr.

    1981-05-08

    Reaction of cyclooctatetraene (COT) with tert-butyllithium provides a convenient synthesis of tert-butylcyclooctatetraene, 4. As a byproduct of the reaction mixture, 1,4-di-tert-butylcyclooctatriene has been isolated and converted to 1,4-di-tert-butylcyclooctatetraene, 5, by deprotonation with potassium amide and oxidation with iodine. An independent synthesis of 5 was developed from 9-oxabicyclo(6.1.0)octa-2,4,6-triene (cyclooctatetraene oxide), 9. The highly substituted compound 1,3,5,7-tetra-tert-butylcyclooctatetraene (6) has been prepared in 24% overall yield in four steps. The acetylenic ketone 27, prepared from (tert-butylethynyl)copper and pivaloyl chloride, undergoes condensation with dimethyl malonate to give the pyrone ester 28. This ester undergoes facile hydrolysis and decarboxylation in hot concentrated sulfuric acid to yield 4,6-di-tert-butyl-2H-pyran-2-one (22) which is converted to 6 in one step by photolysis in dilute solution.

  1. Antioxidant and radical scavenging properties of curcumin.

    PubMed

    Ak, Tuba; Gülçin, Ilhami

    2008-07-10

    Curcumin (diferuoyl methane) is a phenolic compound and a major component of Curcuma longa L. In the present paper, we determined the antioxidant activity of curcumin by employing various in vitro antioxidant assays such as 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH*) scavenging, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, N,N-dimethyl-p-phenylenediamine dihydrochloride (DMPD) radical scavenging activity, total antioxidant activity determination by ferric thiocyanate, total reducing ability determination by the Fe(3+)-Fe(2+) transformation method, superoxide anion radical scavenging by the riboflavin/methionine/illuminate system, hydrogen peroxide scavenging and ferrous ions (Fe(2+)) chelating activities. Curcumin inhibited 97.3% lipid peroxidation of linoleic acid emulsion at 15 microg/mL concentration (20 mM). On the other hand, butylated hydroxyanisole (BHA, 123 mM), butylated hydroxytoluene (BHT, 102 mM), alpha-tocopherol (51 mM) and trolox (90 mM) as standard antioxidants indicated inhibition of 95.4, 99.7, 84.6 and 95.6% on peroxidation of linoleic acid emulsion at 45 microg/mL concentration, respectively. In addition, curcumin had an effective DPPH* scavenging, ABTS*(+) scavenging, DMPD*(+) scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, ferric ions (Fe(3+)) reducing power and ferrous ions (Fe(2+)) chelating activities. Also, BHA, BHT, alpha-tocopherol and trolox, were used as the reference antioxidant and radical scavenger compounds. According to the present study, curcumin can be used in the pharmacological and food industry because of these properties. PMID:18547552

  2. Determination of reactions between free radicals and selected Chilean wines and transition metals by ESR and UV-vis technique

    NASA Astrophysics Data System (ADS)

    Espinoza, Mónica; Olea-Azar, Claudio; Speisky, Hernán; Rodríguez, Jorge

    2009-01-01

    Four different types of Chilean wines (Cabernet Sauvignon, Merlot, Carmenere and Syrah) were selected and examined in their free radical scavenging capacities by electron spin resonance (ESR) and spectrophotometric methods. The free radical scavenging properties were evaluated against 2,2-diphenyl-1-picrylhydrazyl (DPPH rad ) radical, 2,6-di- tert-butyl-alpha-(3,5-di- tert-butyl-4-oxo-2,5-cyclohexadien-1-ylidene)- p-tolyloxy (Galvinoxyl) radical and hydroxyl radical (HO rad ). The possible effect on these scavenging properties of added transition metals to these wines was evaluated. Among the wines evaluated, Cabernet Sauvignon was the one with the highest activity against all radicals tested. The presence of added copper or iron to wines resulted in a reduced free radical scavenging capacity for all type of wines studied. The formation of redox inactive complexes between polyphenols of wine and transition metals is the possible cause of this reduction in antioxidant activity.

  3. Roaming Radicals

    NASA Astrophysics Data System (ADS)

    Bowman, Joel M.; Shepler, Benjamin C.

    2011-05-01

    Roaming is a recently verified unusual pathway to molecular products from unimolecular dissociation of an energized molecule. Here we present the evidence for this pathway for H2CO and CH3CHO. Theoretical analysis shows that this path visits the plateau region of the potential energy surface near dissociation to radical products. It is not clear whether roaming is a distinct isolated pathway, in addition to the conventional one via the well-known molecular saddle-point transition state. Evidence is presented to suggest that the two pathways may originate from a single, but highly complicated, dividing surface. Other examples of unusual reaction dynamics are also reviewed.

  4. Free radical formation in vivo and hepatotoxicity due to anesthesia with halothane

    SciTech Connect

    Plummer, J.L.; Beckwith, A.L.; Bastin, F.N.; Adams, J.F.; Cousins, M.J.; Hall, P.

    1982-09-01

    In vivo studies were undertaken to determine whether free radical formation in the liver during administration of various halogenated anesthetics is associated with hepatotoxicity of these agents in an animal model. In addition to the anesthetics halothane, enflurane, and isoflurane, carbon tetrachloride was studied as an example of a hepatotoxic halogenated compound acting by a free radical mechanism. Free radicals were trapped in vivo during anesthesia as stable adducts using the spin trap, alpha-phenyl-t-butyl nitrone. These adducts were extracted from the liver and studied by electron spin resonance spectrometry. Free radicals were detected after administration of halothane or carbon tetrachloride, compounds which were hepatotoxic under the conditions of the experiment, but were not found after anesthesia induced with enflurane or isoflurane, anesthetics which were not hepatotoxic under identical conditions. The free radical trapped after alpha-phenyl-t-butyl nitrone treatment of halothane-anesthetized rats appeared to be a metabolic intermediate of halothane.

  5. Preparation and application of acidified/calcined red mud catalyst for catalytic degradation of butyl xanthate in Fenton-like process.

    PubMed

    Shao, Luhua; Wei, Guangtao; Wang, Yizhi; Li, Zhongmin; Zhang, Linye; Zhao, Shukai; Zhou, Ming

    2016-08-01

    Acidified/calcined red mud (ACRM), a novel catalyst used in Fenton-like process, was prepared by acidification and calcination of red mud (RM). Catalyst characterization showed that iron phase of ACRM was mainly α-Fe2O3 and ACRM was a porous material with rough surface and loose structure. Degradation of butyl xanthate in Fenton-like process catalyzed by ACRM was investigated. Butyl xanthate was effectively degraded, and the degradation of butyl xanthate was well fitted by second order kinetic model. ACRM had an excellent long-term stability in a Fenton-like process. The possible mechanisms of hydroxyl radical production and butyl xanthate degradation in a Fenton-like process catalyzed by ACRM were presented. PMID:27094281

  6. Peptide ligation from alkoxyamine based radical addition.

    PubMed

    Trimaille, Thomas; Autissier, Laurent; Rakotonirina, Mamy Daniel; Guillaneuf, Yohann; Villard, Claude; Bertin, Denis; Gigmes, Didier; Mabrouk, Kamel

    2014-03-14

    Intermolecular radical 1,2-addition (IRA) of N-tert-butyl-N-(1-diethylphosphono-2,2-dimethylpropyl)aminoxyl (SG1) based alkoxyamines onto activated olefins is used as a tool for peptide ligation. This strategy relies on simple peptide pre-derivatization to obtain (i) a SG1 nitroxide functionalized resin peptide at its N-terminus (SG1-peptide alkoxyamine), (ii) a vinyl functionalized peptide (either at its C-terminus or N-terminus), and does not require any coupling agents. PMID:24476638

  7. 40 CFR 721.4925 - Methyl n-butyl ketone.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Methyl n-butyl ketone. 721.4925... Substances § 721.4925 Methyl n-butyl ketone. (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance methyl n-butyl ketone, CAS Number 591-78-6, is subject to...

  8. 40 CFR 721.4925 - Methyl n-butyl ketone.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Methyl n-butyl ketone. 721.4925... Substances § 721.4925 Methyl n-butyl ketone. (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance methyl n-butyl ketone, CAS Number 591-78-6, is subject to...

  9. 40 CFR 721.4925 - Methyl n-butyl ketone.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Methyl n-butyl ketone. 721.4925... Substances § 721.4925 Methyl n-butyl ketone. (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance methyl n-butyl ketone, CAS Number 591-78-6, is subject to...

  10. 40 CFR 721.4925 - Methyl n-butyl ketone.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Methyl n-butyl ketone. 721.4925... Substances § 721.4925 Methyl n-butyl ketone. (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance methyl n-butyl ketone, CAS Number 591-78-6, is subject to...

  11. 21 CFR 520.260 - n-Butyl chloride capsules.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... body weight. Capsules containing 442 milligrams of n-butyl chloride are administered to dogs weighing... 21 Food and Drugs 6 2012-04-01 2012-04-01 false n-Butyl chloride capsules. 520.260 Section 520.260... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.260 n-Butyl chloride...

  12. 21 CFR 520.260 - n-Butyl chloride capsules.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... body weight. Capsules containing 442 milligrams of n-butyl chloride are administered to dogs weighing... 21 Food and Drugs 6 2011-04-01 2011-04-01 false n-Butyl chloride capsules. 520.260 Section 520.260... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.260 n-Butyl chloride...

  13. 21 CFR 520.260 - n-Butyl chloride capsules.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... body weight. Capsules containing 442 milligrams of n-butyl chloride are administered to dogs weighing... 21 Food and Drugs 6 2010-04-01 2010-04-01 false n-Butyl chloride capsules. 520.260 Section 520.260... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.260 n-Butyl chloride...

  14. 40 CFR 721.3438 - Chlorohydroxyalkyl butyl ether (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Chlorohydroxyalkyl butyl ether... Specific Chemical Substances § 721.3438 Chlorohydroxyalkyl butyl ether (generic). (a) Chemical substance... chlorohydroxyalkyl butyl ether (PMN P-99-1295) is subject to reporting under this section for the significant new...

  15. 40 CFR 721.3438 - Chlorohydroxyalkyl butyl ether (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Chlorohydroxyalkyl butyl ether... Specific Chemical Substances § 721.3438 Chlorohydroxyalkyl butyl ether (generic). (a) Chemical substance... chlorohydroxyalkyl butyl ether (PMN P-99-1295) is subject to reporting under this section for the significant new...

  16. Methyl tert-butyl ether (MTBE)

    Integrated Risk Information System (IRIS)

    Methyl tert - butyl ether ( MTBE ) ; CASRN 1634 - 04 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments f

  17. The sonolytic destruction of methyl tert-butyl ether present in contaminated groundwater.

    PubMed

    Hung, Hui-Ming; Kang, Joon-Wun; Hoffmann, Michael R

    2002-01-01

    Ultrasonic irradiation in the presence of ozone was used to efficiently eliminate methyl tert-butyl ether (MTBE) from groundwater. The sonolytic degradation of MTBE was investigated in three different reactor configurations and frequencies: vibrating-plate reactor (VPR, 358 kHz), near-field acoustical processor (NAP 20 and 16 kHz), and radial-tube resonator (RTR. 20 kHz). The sonochemical reactors can be ordered in terms of their efficiency with respect to the degradation of MTBE in the following way: VPR > RTR > NAP. The higher elimination rates of MTBE in groundwater by combined ultrasound-ozone systems are attributed to the effective conversion of ozone to the OH radical, even in the presence of high alkalinity. Carbonate radicals, which were formed from the oxidation of bicarbonate by hydroxyl radicals, are shown to react with MTBE via a hydrogen-atom abstraction pathway. Methyl-tert-butyl ether was also rapidly eliminated from the groundwater underlying a major intemational airport by direct chemical oxidation with a mixture of hydrogen peroxide and ozone. PMID:12540095

  18. Rate constants for the reactions of free radicals with oxygen in solution

    SciTech Connect

    Maillard, B.; Ingold, K.U.; Scaiano, J.C.

    1983-07-27

    The kinetics of the rections of several free radicals with oxygen have been examined in solution at 300 K using laser flash photolysis techniques. The reactions of resonance-stabilized radicals are only slightly slower than those of nonstabilized radicals: for example, for tert-butyl (in cyclohexane), 4.93 x 10/sup 9/; benzyl, 2.36 x 10/sup 9/ (in cyclohexane); cyclohexadienyl (in benzene), 1.64 x 10/sup 9/ M/sup -1/ s/sup -1/. The reaction of butyl-tin (n-Bu/sub 3/Sn.) radicals is unusually fast (7.5 x 10/sup 9/ M/sup -1/ s/sup -1/), a fact that has been tentatively attributed to a relaxation of spin selection rules due to heavy atom effects. 1 table.

  19. Free radicals, antioxidants and functional foods: Impact on human health

    PubMed Central

    Lobo, V.; Patil, A.; Phatak, A.; Chandra, N.

    2010-01-01

    In recent years, there has been a great deal of attention toward the field of free radical chemistry. Free radicals reactive oxygen species and reactive nitrogen species are generated by our body by various endogenous systems, exposure to different physiochemical conditions or pathological states. A balance between free radicals and antioxidants is necessary for proper physiological function. If free radicals overwhelm the body's ability to regulate them, a condition known as oxidative stress ensues. Free radicals thus adversely alter lipids, proteins, and DNA and trigger a number of human diseases. Hence application of external source of antioxidants can assist in coping this oxidative stress. Synthetic antioxidants such as butylated hydroxytoluene and butylated hydroxyanisole have recently been reported to be dangerous for human health. Thus, the search for effective, nontoxic natural compounds with antioxidative activity has been intensified in recent years. The present review provides a brief overview on oxidative stress mediated cellular damages and role of dietary antioxidants as functional foods in the management of human diseases. PMID:22228951

  20. Copper(I)-Catalyzed Radical Addition of Acetophenones to Alkynes in Furan Synthesis.

    PubMed

    Manna, Srimanta; Antonchick, Andrey P

    2015-09-01

    A synthesis of multisubstituted furans from readily available acetophenones and electron-deficient alkynes via direct C(sp(3))-H bond functionalization under radical reaction conditions is described. The developed transformation is catalyzed by copper(I) salts using di-tert-butyl peroxide as an external oxidant. This method offers an efficient access to biologically important scaffolds from simple compounds. PMID:26277912

  1. The mechanism of catalytic methylation of 2-phenylpyridine using di-tert-butyl peroxide.

    PubMed

    Sharma, Akhilesh K; Roy, Dipankar; Sunoj, Raghavan B

    2014-07-14

    The mechanism of palladium chloride-catalyzed direct methylation of arenes with peroxides is elucidated by using the energetics computed at the M06 density functional theory. The introduction of a methyl group by tert-butyl peroxides at the ortho-position of a prototypical 2-phenyl pyridine, a commonly used substrate in directed C-H functionalization reactions, is examined in detail by identifying the key intermediates and transition states involved in the reaction sequence. Different possibilities that differ in terms of the site of catalyst coordination with the substrate and the ensuing mechanism are presented. The important mechanistic events involved are (a) an oxidative or a homolytic cleavage of the peroxide O-O bond, (b) C-H bond activation, (c) C-C bond activation, and (d) reductive elimination involving methyl transfer to the aromatic ring. We have examined both radical and non-radical pathways. In the non-radical pathway, the lowest energy pathway involves C-H bond activation prior to the coordination of the peroxide to palladium, which is subsequently followed by the O-O bond cleavage of the peroxide and the C-C bond activation. Reductive elimination in the resulting intermediate leads to the vital C-C bond formation between methyl and aryl carbon atoms. In the non-radical pathway, the C-C bond activation is higher in energy and has been identified as the rate-limiting step of this reaction. In the radical pathway, however, the activation barrier for the C-C bond cleavage is lower than for the peroxide O-O bond cleavage. A combination of a radical pathway up to the formation of a palladium methyl intermediate and a subsequent non-radical pathway has been identified as the most favored pathway for the title reaction. The predicted mechanism is in good agreement with the experimental observations on PdCl2 catalyzed methylation of 2-phenyl pyridine using tert-butyl peroxide. PMID:24875675

  2. Polymerization rate and mechanism of ultrasonically initiated emulsion polymerization of n-butyl acrylate.

    PubMed

    Xia, Hesheng; Wang, Qi; Liao, Yongqin; Xu, Xi; Baxter, Steven M; Slone, Robert V; Wu, Shuguang; Swift, Graham; Westmoreland, David G

    2002-07-01

    The factors affecting the induction period and polymerization rate in ultrasonically initiated emulsion polymerization of n-butyl acrylate (BA) were investigated. The induction period takes only an instant in ultrasonically initiated emulsion polymerization of BA without any added initiator by enhancing the N2 flow rate. Increasing temperature, power output and SDS concentration, decreasing the monomer concentration results in further decreasing induction period and enhanced polymerization rate. Under optimized reaction conditions the conversion of BA reaches 92% in 11 min. The polymerization rate can be controlled by varying reaction parameters. The apparatus of ultrasonically initiated semi-continuous and continuous emulsion polymerization were set up and the feasibility was first studied. Based on the experimental results, a free radical polymerization mechanism for ultrasonically initiated emulsion polymerization was proposed, including the sources of the radicals, the process of radical formation, the locus of polymerization and the polymerization process. Compared with conventional emulsion polymerization, where the radicals come from thermal decomposition of a chemical initiator, ultrasonically initiated emulsion polymerization has attractive features such as no need for a chemical initiator, lower reaction temperature, faster polymerization rate, and higher molecular weight of the polymer prepared. PMID:12154689

  3. On the Reaction of FNO2 with CH3, t-butyl, and C13H21

    NASA Technical Reports Server (NTRS)

    Thuemmel, H. T.; Bauschlicher, Charles W., Jr.; Arnold, James O. (Technical Monitor)

    1996-01-01

    Theoretical studies are reported for the reaction of FN02 with the radicals CH3, t-butyl, and C13H21, which are templates for the radical site of a hydrogenated diamond surface. All structures axe fully optimized using density functional theory (DFT) based on the B3LYP functional. Calibration calculations axe performed for CH3 + FNO2 using the coupled cluster approach, the the internally contracted multireference configuration. interaction method, and second order perturbation theory based upon complete active space SCF (CASSCF) reference wave function. These calibration calculations support the B3LYP approach for the calculation of bond energies, but show the B3LYP barrier is too low. Combining the calibration calculations with the larger clusters yields our best estimate of a barrier of about 10 kcal/mol. for the reaction of FNO2 with a radical site on hydrogenated diamond.

  4. Steric Effects in the Reaction of Aryl Radicals on Surfaces

    SciTech Connect

    Combellas, Catherine; Jiang, Deen; Kanoufi, Frederic; Pinson, Jean; Podvorica, Fetah

    2009-01-01

    Steric effects are investigated in the reaction of aryl radicals with surfaces. The electrochemical reduction of 2-, 3-, 4-methyl, 2-methoxy, 2-ethyl, 2,6-, 2,4-, and 3,5-dimethyl, 4-tert-butyl, 3,5-bis-tert-butyl benzenediazonium, 3,5-bis(trifluoromethyl), and pentafluoro benzenediazonium tetrafluoroborates is examined in acetonitrile solutions. It leads to the formation of grafted layers only if the steric hindrance at the 2- or 2,6-position(s) is small. When the 3,5-positions are crowded with tert-butyl groups, the growth of the organic layer is limited by steric effects and a monolayer is formed. The efficiency of the grafting process is assessed by cyclic voltammetry, X-ray photoelectron spectroscopy, infrared, and ellipsometry. These experiments, together with density functional computations of bonding energies of substituted phenyl groups on a copper surface, are discussed in terms of the reactivity of aryl radicals in the electrografting reaction and in the growth of the polyaryl layer.

  5. ESR spin trapping for characterization of radical formation in Lactobacillus acidophilus NCFM and Listeria innocua.

    PubMed

    Hougaard, Anni B; Arneborg, Nils; Andersen, Mogens L; Skibsted, Leif H

    2013-09-01

    In this study, radicals in pure cultures of Lactobacillus acidophilus NCFM and Listeria innocua were detected in a quantitative way by electron spin resonance spectroscopy using spin trapping with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) or N-tert-butyl-α-phenylnitrone (PBN). No adverse effect of spin trap addition on viability was observed for any of the bacterial strains. L. acidophilus NCFM had a higher production of radicals than L. innocua when incubated in a growth medium. Furthermore, by using DMPO in a buffer system, the radicals produced by L. acidophilus NCFM could be identified as hydroxyl radicals. The presence of polyethylene glycol, impermeable for bacterial cells, decreased the signal intensity of the ESR spectrum of the DMPO-OH adduct in cultures of L. acidophilus NCFM and indicated quenching of hydroxyl radicals outside the bacteria. This suggests that radical production is an extracellular event for L. acidophilus NCFM. PMID:23811362

  6. Radical prostatectomy - discharge

    MedlinePlus

    ... prostatectomy - discharge; Laparoscopic radical prostatectomy - discharge; LRP - discharge; Robotic-assisted laparoscopic prostatectomy - discharge ; RALP - discharge; Pelvic lymphadenectomy - ...

  7. Sunlight and free radicals

    NASA Astrophysics Data System (ADS)

    Tidwell, Thomas

    2013-08-01

    Thomas Tidwell reflects on the overlooked -- but prescient -- proposal by the British chemists Arthur Downes and Thomas Blunt for photochemical free-radical formation, decades before Moses Gomberg launched the field of radical chemistry by preparing triphenylmethyl, the first stable organic radical.

  8. 40 CFR 721.4925 - Methyl n-butyl ketone.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Methyl n-butyl ketone. 721.4925 Section 721.4925 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4925 Methyl n-butyl ketone....

  9. 21 CFR 520.260 - n-Butyl chloride.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... a dosage level of 1 capsule per 21/2 pounds body weight. Capsules containing 884 milligrams of n... 21 Food and Drugs 6 2014-04-01 2014-04-01 false n-Butyl chloride. 520.260 Section 520.260 Food and..., FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.260 n-Butyl chloride....

  10. 21 CFR 520.260 - n-Butyl chloride.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... a dosage level of 1 capsule per 21/2 pounds body weight. Capsules containing 884 milligrams of n... 21 Food and Drugs 6 2013-04-01 2013-04-01 false n-Butyl chloride. 520.260 Section 520.260 Food and..., FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.260 n-Butyl chloride....

  11. From Molecules to Surfaces: Radical-Based Mechanisms of Si-S and Si-Se Bond Formation on Silicon.

    PubMed

    Buriak, Jillian M; Sikder, Md Delwar H

    2015-08-01

    The derivatization of silicon surfaces can have profound effects on the underlying electronic properties of the semiconductor. In this work, we investigate the radical surface chemistry of silicon with a range of organochalcogenide reagents (comprising S and Se) on a hydride-terminated silicon surface, to cleanly and efficiently produce surface Si-S and Si-Se bonds, at ambient temperature. Using a diazonium-based radical initiator, which induces formation of surface silicon radicals, a group of organochalcogenides were screened for reactivity at room temperature, including di-n-butyl disulfide, diphenyl disulfide, diphenyl diselenide, di-n-butyl sulfide, diphenyl selenide, diphenyl sulfide, 1-octadecanethiol, t-butyl disulfide, and t-butylthiol, which comprises the disulfide, diselenide, thiol, and thioether functionalities. The surface reactions were monitored by transmission mode Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy, and time-of-flight secondary ionization mass spectrometry. Calculation of Si-Hx consumption, a semiquantitative measure of yield of production of surface-bound Si-E bonds (E = S, Se), was carried out via FTIR spectroscopy. Control experiments, sans the BBD diazonium radical initiator, were all negative for any evident incorporation, as determined by FTIR spectroscopy. The functional groups that did react with surface silicon radicals included the dialkyl/diphenyl disulfides, diphenyl diselenide, and 1-octadecanethiol, but not t-butylthiol, diphenyl sulfide/selenide, and di-n-butyl sulfide. Through a comparison with the rich body of literature regarding molecular radicals, and in particular, silyl radicals, reaction mechanisms were proposed for each. Armed with an understanding of the reaction mechanisms, much of the known chemistry within the extensive body of radical-based reactivity has the potential to be harnessed on silicon and could be extended to a range of technologically relevant semiconductor

  12. Protective effect of Pterostilbene against free radical mediated oxidative damage

    PubMed Central

    2013-01-01

    Background Pterostilbene, a methoxylated analog of Resveratrol, is gradually gaining more importance as a therapeutic drug owing to its higher lipophilicity, bioavailability and biological activity than Resveratrol. This study was undertaken to characterize its ability to scavenge free radicals such as superoxide, hydroxyl and hydrogen peroxide and to protect bio-molecules within a cell against oxidative insult. Methods Anti-oxidant activity of Pterostilbene was evaluated extensively by employing several in vitro radical scavenging/inhibiting assays and pulse radiolysis study. In addition, its ability to protect rat liver mitochondria against tertiary-butyl hydroperoxide (TBHP) and hydroxyl radical generated oxidative damage was determined by measuring the damage markers such as protein carbonyls, protein sulphydryls, lipid hydroperoxides, lipid peroxides and 8-hydroxy-2'-deoxyguanosine. Pterostilbene was also evaluated for its ability to inhibit •OH radical induced single strand breaks in pBR322 DNA. Result Pterostilbene exhibited strong anti-oxidant activity against various free radicals such as DPPH, ABTS, hydroxyl, superoxide and hydrogen peroxide in a concentration dependent manner. Pterostilbene conferred protection to proteins, lipids and DNA in isolated mitochondrial fractions against TBHP and hydroxyl radical induced oxidative damage. It also protected pBR322 DNA against oxidative assault. Conclusions Thus, present study provides an evidence for the strong anti-oxidant property of Pterostilbene, methoxylated analog of Resveratrol, thereby potentiating its role as an anti-oxidant. PMID:24070177

  13. Contemporary Radical Prostatectomy

    PubMed Central

    Fu, Qiang; Moul, Judd W.; Sun, Leon

    2011-01-01

    Purpose. Patients diagnosed with clinically localized prostate cancer have more surgical treatment options than in the past. This paper focuses on the procedures' oncological or functional outcomes and perioperative morbidities of radical retropubic prostatectomy, radical perineal prostatectomy, and robotic-assisted laparoscopic radical prostatectomy. Materials and Methods. A MEDLINE/PubMed search of the literature on radical prostatectomy and other new management options was performed. Results. Compared to the open procedures, robotic-assisted radical prostatectomy has no confirmed significant difference in most literatures besides less blood loss and blood transfusion. Nerve sparing is a safe means of preserving potency on well-selected patients undergoing radical prostatectomy. Positive surgical margin rates of radical prostatectomy affect the recurrence and survival of prostate cancer. The urinary and sexual function outcomes have been vastly improved. Neoadjuvant treatment only affects the rate of positive surgical margin. Adjuvant therapy can delay and reduce the risk of recurrence and improve the survival of the high risk prostate cancer. Conclusions. For the majority of patients with organ-confined prostate cancer, radical prostatectomy remains a most effective approach. Radical perineal prostatectomy remains a viable approach for patients with morbid obesity, prior pelvic surgery, or prior pelvic radiation. Robot-assisted laparoscopic prostatectomy (RALP) has become popular among surgeons but has not yet become the firmly established standard of care. Long-term data have confirmed the efficacy of radical retropubic prostatectomy with disease control rates and cancer-specific survival rates. PMID:22110994

  14. Toxic effects of butyl elastomers on aerobic methane oxidation

    NASA Astrophysics Data System (ADS)

    Niemann, Helge; Steinle, Lea I.; Blees, Jan H.; Krause, Stefan; Bussmann, Ingeborg; Lehmann, Moritz F.; Treude, Tina

    2013-04-01

    Large quantities of the potent greenhouse gas methane are liberated into the water column of marine and lacustrine environments where it may be consumed by aerobic methane oxidising bacteria before reaching the atmosphere.The reliable quantification of aerobic methane oxidation (MOx) rates is consequently of paramount importance for estimating methane budgets and to understand the controls on water column methane cycling. A widely used set of methods for measuring MOx rates is based on the incubation of water samples during which the consumption of methane is monitored, for instance with radio-tracer assays. Typically, incubation vessels are sealed with butyl rubber stoppers because these elastomers are essentially impermeable for gases at the relevant time scales. We tested the effect of different stopper materials (unmodified- and halogenated butyl rubber) on MOx activity in environmental samples and in cultures of methane oxidising bacteria. MOx rates in samples sealed with unmodified butyl rubber were > 75% lower compared to parallel incubations with halogenated butyl rubber seals, suggesting inhibiting/toxic effects associated with the use of unmodified butyl elastomers. To further explore the cause of these effects, we analysed aqueous extracts of the different stoppers. Halogenated butyl rubber stoppers appeared to bleed off comparably little amounts of organics. In stark contrast, extracts of unmodified butyl rubber were contaminated with various organic compounds including potential bactericides such as benzyltoluenes, phenylalkanes and benzuothiazoles. We also found tetramethylthiourea, a scavenger of active oxygen species, which may inhibit the MOx pathway.

  15. Electronic states of alkyl-radical-functionalized C20 fullerene using density functional theory

    NASA Astrophysics Data System (ADS)

    Abe, Shigeaki; Kawano, Shimpei; Toida, Yu; Nakamura, Mariko; Inoue, Satoshi; Sano, Hidehiko; Yoshida, Yasuhiro; Kawabata, Hiroshi; Tachikawa, Hiroto

    2016-03-01

    The structures and electronic states of alkyl-radical-functionalized C20 fullerenes (denoted by C20-R) have been investigated using density functional theory (DFT). The different alkyl radicals investigated were methyl, ethyl, propyl, and butyl radicals. The DFT calculation indicated that the alkyl radical binds to the carbon atom of C20 in the on-top site, thus forming a strong C-C single bond. The binding energies of the alkyl radicals to C20 were calculated to be 83.9-86.6 kcal/mol at the CAM-B3LYP/6-311G(d,p) level. The electronic states of the C20-R complex are discussed on the basis of the theoretical results.

  16. The reorientation of t-butyl groups in butylated hydroxytoluene: A deuterium nuclear magnetic resonance spectral and relaxation time study

    NASA Astrophysics Data System (ADS)

    Polson, James M.; Fyfe, J. D. Dean; Jeffrey, Kenneth R.

    1991-03-01

    Deuterium nuclear magnetic resonance (NMR) spectra and spin-lattice relaxation times were determined in order to study the dynamics of t-butyl groups in butylated hydroxytoluene. The results are consistent with a model first proposed by Beckmann et al. [J. Magn. Reson. 36, 199 (1979)], where there is an inequivalence between the methyl groups within each t-butyl group. While two methyl groups reorient rapidly relative to the whole t-butyl rotation, the remaining methyl group is more restricted in its motion, reorienting at a rate comparable to that of the t-butyl group itself. The spin-lattice relaxation data show two T1 minima, the high temperature minimum (40 °C) corresponding to the combined t-butyl and ``slow'' methyl rotations, and the low temperature minimum corresponding to ``fast'' methyl group rotation. Using an explicitly defined T1 fitting function, the T1 data yield activation energies of 2.2 and 6.0 kcal/mol for the fast methyl and t-butyl rotations, respectively, both in agreement with Beckmann's values obtained from proton T1 experiments. It was also possible to simulate the low temperature deuterium NMR spectra from T=-160 °C to T=-80 °C using the aforementioned dynamical inequivalence between the t-butyl methyl groups. While the fast methyl group rotation was in the motional narrowing region for T>-160 °C, it was possible, from the simulations, to determine the t-butyl exchange rates to within 10%. The jump rates are remarkably close to the values predicted from the T1 results. Above -80 °C, the spectra could not be simulated, implying that a third motion must be present to further alter the high temperature line shapes. The effective axial asymmetry of the T>-20° spectra indicates that the additional motion involves a two site exchange.

  17. Kinetics and mechanism of alkane hydroperoxidation with tert-butyl hydroperoxide catalysed by a vanadate anion.

    PubMed

    Shul'pin, Georgiy B; Kozlov, Yuriy N

    2003-07-01

    tert-Butyl hydroperoxide oxidizes alkanes in acetonitrile at 60 degrees C if the soluble vanadium(v) salt, n-Bu4NVO3, is used as a catalyst. Alkyl hydroperoxides are formed as main products which decompose during the course of the reaction to produce the more stable corresponding alcohols and ketones. Turnover numbers (ie. numbers of moles of products per one mole of a catalyst) attained 250. The kinetics and selectivity of the reaction have been studied. The mechanism proposed involves the formation of a complex between the V(V) species and t-BuOOH (K5 was estimated to be 5 dm3 mol(-1)) followed by decomposition of this complex (k6 = 0.2 s(-1)). The generated V(IV) species reacts with another t-BuOOH molecule to produce an active t-BuO* radical which attacks the hydrocarbon. PMID:12945701

  18. Quantification of hypoglycin A as butyl ester.

    PubMed

    Sander, Johannes; Terhardt, Michael; Sander, Stefanie; Janzen, Nils

    2016-09-01

    L-α-amino-methylenecyclopropyl propionic acid (Hypoglycin A, HGA) has been found to be the toxic compound in fruits of the Sapindaceae family causing acute intoxication when ingested as food or feed. Clinical symptoms are consistent with acquired multiple acyl-CoA dehydrogenase deficiency (MADD). Ultra performance liquid chromatography-tandem mass spectrometry was used to measure HGA after butylation. Sample volumes were 10μL for serum and 20μL for urine. Internal standard for HGA was d3-leucine, samples were plotted on a 7-point linear calibration curve. Coefficients of variation were <15% at 0.01μmol HGA/L and ≤4.1% at 10μmol/L. R(2) values for linearity were ≥0.995. In order to quantify non-metabolized HGA together with some of its metabolites plus a spectrum of acyl glycines and acyl carnitines typical for acquired MADD in one single analysis HGA measurement was integrated into a method which we previously developed for metabolites of HGA and acyl conjugates. The new method is suitable for biochemical diagnosis of Ackee fruit poisoning or atypical myopathy in horses and for forensic purposes in cases of suspected HGA poisoning. PMID:27433981

  19. NQR in tert-butyl chloride

    NASA Astrophysics Data System (ADS)

    Brunetti, Aldo H.

    2004-03-01

    Tert-butyl chloride has been broadly studied experimentally through various techniques such as X-ray crystallography, DTA, and NMR. It was also studied experimentally through nuclear quadrupole resonance (NQR), but this study was limited and incomplete. In this paper, we present a more detailed study of TBC through the NQR of 35Cl. Our results show that near 120 K, the onset of the CH 3 groups semirotations around symmetry axis C3 takes place with an activation energy U=16.1 kJ mol -1. This intramolecular movement produces a T1 minimum near 148 K and is the dominant mechanism of the nuclear spin-lattice relaxation in phase III of this compound. In phase II of TBC, we show that there are not only methyl groups semirotations, but also semirotations of the whole molecule around a different axis from the symmetry axis C' 3 (C-Cl bond) with an activation energy of E=10.4 kJ mol -1.

  20. Reassessing Radical Pedagogy.

    ERIC Educational Resources Information Center

    Sweet, Stephen

    1998-01-01

    Responds to comments about, and critiques of, his own article on radical pedagogy. Outlines major points of contention raised by other commentators and responds to them, including matters of definition, power relations in the classroom, and tempering radical theory with pragmatism. (DSK)

  1. [Alchemists' humid radical].

    PubMed

    Lafont, Olivier

    2007-01-01

    The term radical has been used by chemists since the beginnings and even when they still were alchemists. The term "humid radical" is present in numerous alchemists' texts. It was used to represent a kind of "humid", which was considered as different from what is nowadays called "humid", but was a sort of principle necessary for life. PMID:17575839

  2. Involvement of free radicals in excitotoxicity in vivo.

    PubMed

    Schulz, J B; Henshaw, D R; Siwek, D; Jenkins, B G; Ferrante, R J; Cipolloni, P B; Kowall, N W; Rosen, B R; Beal, M F

    1995-05-01

    Recent evidence has linked excitotoxicity with the generation of free radicals. We examined whether free radical spin traps can attenuate excitotoxic lesions in vivo. Pretreatment with N-tert-butyl-alpha-(2-sulfophenyl)-nitrone (S-PBN) significantly attenuated striatal excitotoxic lesions in rats produced by N-methyl-D-aspartate (NMDA), kainic acid, and alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA). In a similar manner, striatal lesions produced by 1-methyl-4-phenylpyridinium (MPP+), malonate, and 3-acetylpyridine were significantly attenuated by either S-PBN or alpha-phenyl-N-tert-butylnitrone (PBN) treatment. Administration of S-PBN in combination with the NMDA antagonist MK-801 produced additive effects against malonate and 3-acetylpyridine toxicity. Malonate injections resulted in increased production of hydroxyl free radicals (.OH) as assessed by the conversion of salicylate to 2,3- and 2,5-dihydroxybenzoic acid (DHBA). This increase was significantly attenuated by S-PBN, consistent with a free radical scavenging effect. S-PBN had no effects on malonate-induced ATP depletions and had no significant effect on spontaneous striatal electrophysiologic activity. These results provide the first direct in vivo evidence for the involvement of free radicals in excitotoxicity and suggest that antioxidants may be useful in treating neurologic illnesses in which excitotoxic mechanisms have been implicated. PMID:7536809

  3. Photochemistry of dipenylketyl radicals: spectroscopy, kinetics, and mechanisms

    SciTech Connect

    Johnston, L.J.; Lougnot, D.J.; Wintgens, V.; Scaiano, J.C.

    1988-01-20

    The photochemistry of the diphenylketyl radical has been examined in nonpolar solutions. Transient studies using two-laser techniques yield an excited-state lifetime of 3.9 ns in toluene at room temperature, while for diphenylketyl-O-d the lifetime is 8.7 ns. Dye laser irradiation (515 nm) in the ketyl's visible absorption band leads to efficient photobleaching with Phi/sub bleach/ = 0.27 +/- 0.06 for the parent radical and 0.39 and 0.26 for the 4-methyl and 4-chloro derivatives, respectively. The photobleaching reaction involves the cleavage of the O-H ketyl bond to yield benzophenone and hydrogen atoms; in cyclohexane the latter abstract hydrogen from the solvent to produce molecular hydrogen which was characterized by Raman spectroscopy. In accordance with this mechanism, two-laser experiments produce lower yields of photoreduction products than the one-laser experiments in which the ketyls are not photobleached. When the ketyl radicals are generated by reaction of tert-butoxy radicals with benzhydrol, dye laser irradiation leads to a large increase in the yield of benzophenone (now a product), although the mechanism here is somewhat more complex due to the quenching of excited ketyl radicals by di-tert-butyl peroxide (k/sub q/ = 1.9 x 10/sup 9/ M/sup -1/ s/sup -1/). Detailed studies of the fluorescence, isotope effects, temperature effects, and products are also included.

  4. Instrumental laboratories based on the analysis of butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA)

    NASA Astrophysics Data System (ADS)

    Wiginton, John Franklin

    A semester-long series of instrumental analysis laboratory activities appropriate for advanced undergraduate and graduate students is described. The activities incorporate five analytical instruments commonly found in post-secondary educational, industrial, and governmental laboratories: a gas chromatograph with a flame ionization detector (GC), a gas chromatograph with a mass specific detector (GC/MS), a high-pressure liquid chromatograph with a UV-Visible detector (HPLC), a high-performance liquid chromatograph with a mass specific detector (LC/MS), and a nuclear magnetic resonance spectrometer (NMR). The series of activities utilizes two analytes, butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA), which are qualitatively and quantitatively analyzed, then structurally characterized. The protocol for each laboratory activity directs students to accomplish a specific analysis in the most efficient manner, but leaves the actual procedure vague enough to give the student a chance to experiment with the instrument. Student success is assessed by two means, having the student submit a detailed journal-style lab report and a class-wide discussion regarding the development of experimental protocols and individual instrument capabilities and limitations.

  5. Cytotoxicity of butylated hydroxyanisole and butylated hydroxytoluene in isolated rat hepatocytes.

    PubMed

    Thompson, D; Moldéus, P

    1988-06-01

    The effects of the antioxidants butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) on isolated rat hepatocytes were investigated. Both antioxidants were observed to be cytotoxic in a concentration-dependent manner at concentrations ranging from 100 to 750 microM. At equimolar concentrations BHT was more cytotoxic than BHA. Their toxicity appeared to be independent of their metabolism to reactive intermediates since inhibitors of cytochrome P-450 (metyrapone, SKF 525-A and piperonyl butoxide) had no effect on the cytotoxicity and N-acetylcysteine was also without protective effect. In addition, deuterated BHT was equitoxic with BHT. Only low temperature incubation (4 degrees), which has previously been shown to inhibit the insertion of these compounds into biomembranes, was effective in inhibiting the cytotoxic effects. Using isolated rat liver mitochondria we observed that both BHA and BHT inhibited respiratory control primarily by stimulating state 4 respiration and thus acting as membrane uncouplers. BHA and BHT also effectively dissipated membrane potential across the mitochondrial membrane and caused the release of calcium and mitochondrial swelling. These mitochondrial effects were reflected by a rapid decrease in ATP levels in intact hepatocytes which preceded cell death. These results suggest that the observed cytotoxicity of BHA and BHT to hepatocytes is related to their effects on biomembranes and mitochondrial bioenergetics. PMID:3377819

  6. In vivo copper-mediated free radical production: an ESR spin-trapping study

    NASA Astrophysics Data System (ADS)

    Kadiiska, Maria B.; Mason, Ronald P.

    2002-04-01

    Copper has been suggested to facilitate oxidative tissue injury through a free radical-mediated pathway analogous to the Fenton reaction. By applying the electron spin resonance (ESR) spin-trapping technique, evidence for hydroxyl radical formation in vivo was obtained in rats treated simultaneously with copper and ascorbic acid or paraquat. A secondary radical spin-trapping technique was used in which the hydroxyl radical formed the methyl radical upon reaction with dimethylsulfoxide. The methyl radical was then detected by ESR spectroscopy as its adduct with the spin trap phenyl- N- t-butyl- nitrone (PBN). In contrast, lipid derived radical was detected in vivo in copper-challenged, vitamin E and selenium-deficient rats. These findings support the proposal that dietary selenium and vitamin E can protect against lipid peroxidation and copper toxicity. Since copper excreted into the bile from treated animals is expected to be maintained in the Cu(I) state (by ascorbic acid or glutathione), a chelating agent that would redox-stablilize it in the Cu(I) state was used to prevent ex vivo redox chemistry. Bile samples were collected directly into solutions of bathocuproinedisulfonic acid, a Cu(I)-stabilizing agent, and 2,2'-dipyridyl, a Fe(II)-stabilizing agent. If these precautions were not taken, radical adducts generated ex vivo could be mistaken for radical adducts produced in vivo and excreted into the bile.

  7. Reaction products and mechanisms for the reaction of n-butyl vinyl ether with the oxidants OH and Cl: Atmospheric implications

    NASA Astrophysics Data System (ADS)

    Colmenar, Inmaculada; Martín, Pilar; Cabañas, Beatriz; Salgado, Sagrario; Tapia, Araceli; Martínez, Ernesto

    2015-12-01

    A reaction product study for the degradation of butyl vinyl ether (CH3(CH2)3OCHdbnd CH2) by reaction with chlorine atoms (Cl) and hydroxyl radicals (OH) has been carried out using Fourier Transform Infrared absorption spectroscopy (FTIR) and/or Gas Chromatography-Mass Spectrometry with a Time of Flight analyzer (GC-TOFMS). The rate coefficient for the reaction of butyl vinyl ether (BVE) with chlorine atoms has also been evaluated for the first time at room temperature (298 ± 2) K and atmospheric pressure (708 ± 8) Torr. The rate coefficient obtained was (9.9 ± 1.5) × 10-10 cm3 molecule-1 s-1 and this indicates the high reactivity of butyl vinyl ether with Cl atoms. However, this value may be affected by the dark reaction of BVE with Cl2. The results of a qualitative study of the Cl reaction show that the main oxidation products are butyl formate (CH3(CH2)3OC(O)H), butyl chloroacetate (CH3(CH2)3OC(O)CH2Cl and formyl chloride (HCOCl). Individual yields in the ranges ∼16-40% and 30-70% in the absence and presence of NOx, respectively, have been estimated for these products. In the OH reaction, butyl formate and formic acid were identified as the main products, with yields of around 50 and 20%, respectively. Based on the results of this work and a literature survey, the addition of OH radicals and Cl atoms at the terminal C atom of the double bond in CH3(CH2)3OCHdbnd CH2 has been proposed as the first step in the reaction mechanism for both of the studied oxidants. The tropospheric lifetime of butyl vinyl ether is very short and, as a consequence, it will be rapidly degraded and will only be involved in tropospheric chemistry at a local level. The degradation products of these reactions should be considered when evaluating the atmospheric impact.

  8. Radical chemistry of artemisinin

    NASA Astrophysics Data System (ADS)

    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.

  9. α-Tocopherol impact on oxy-radical induced free radical decomposition of DMSO: Spin trapping EPR and theoretical studies

    NASA Astrophysics Data System (ADS)

    Jerzykiewicz, Maria; Ćwieląg-Piasecka, Irmina; Witwicki, Maciej; Jezierski, Adam

    2011-05-01

    EPR spin trapping and theoretical methods such as density functional theory (DFT) as well as combined DFT and quadratic configuration interaction approach (DFT/QCISD) were used to identify the radicals produced in the reaction of oxy-radicals and dimethyl sulfoxide (DMSO) in the presence and absence of α-tocopherol. Additionally, the mixtures of α-tocopherol with linolenic acid and glyceryl trilinoleate as well as bioglycerols (glycerol fractions from biodiesel production) were tested. α-Tocopherol inhibited oxidation of the main decomposition product of DMSO, •CH 3 to •OCH 3 but did not prevent the transformation process of N-t-butyl- α-phenylnitrone (PBN) into 2-methyl-2-nitrosopropane (MNP). Theoretical investigations confirmed the structures of proposed spin adducts and allowed to correlate the EPR parameters observed in the experiment with the spin adducts electronic structure.

  10. Catalytic oxidation of butyl acetate over silver-loaded zeolites.

    PubMed

    Wong, Cheng Teng; Abdullah, Ahmad Zuhairi; Bhatia, Subhash

    2008-09-15

    The performance of silver-loaded zeolite (HY and HZSM-5) catalysts in the oxidation of butyl acetate as a model volatile organic compound (VOC) was studied. The objective was to find a catalyst with superior activity, selectivity towards deep oxidation product and stability. The catalyst activity was measured under excess oxygen condition in a packed bed reactor operated at gas hourly space velocity (GHSV)=15,000-32,000 h(-1), reaction temperature between 150 and 500 degrees C and butyl acetate inlet concentration of 1000-4000 ppm. Both AgY and AgZSM-5 catalysts exhibited high activity in the oxidation of butyl acetate. Despite lower silver content, AgY showed better activity, attributed to better metal dispersion, surface characteristics and acidity, and its pore system. Total conversion of butyl acetate was achieved at above 400 degrees C. The oxidation of butyl acetate followed a simple power law model. The reaction orders, n and m were evaluated under differential mode by varying the VOC partial pressure between 0.004 and 0.018 atm and partial pressure of oxygen between 0.05 and 0.20 atm. The reaction rate was independent of oxygen concentration and single order with respect to VOC concentration. The activation energies were 19.78 kJ/mol for AgY and 32.26 kJ/mol for AgZSM-5, respectively. PMID:18294771

  11. Hydroxyl radicals in indoor environments

    NASA Astrophysics Data System (ADS)

    Sarwar, Golam; Corsi, Richard; Kimura, Yosuke; Allen, David; Weschler, Charles J.

    Indoor hydroxyl radical concentrations were estimated using a new indoor air quality model which employs the SAPRC-99 atmospheric chemistry model to simulate indoor homogenous reactions. Model results indicate that typical indoor hydroxyl radical concentrations are lower than typical outdoor summertime urban hydroxyl radical levels of 5-10×10 6 molecules cm -3; however, indoor levels can be similar to or greater than typical nighttime outdoor hydroxyl radical levels of approximately 5×10 4 molecules cm -3. Effects of selected parameters on indoor hydroxyl radical concentrations are presented herein. Indoor hydroxyl radical concentrations are predicted to increase non-linearly with increasing outdoor ozone concentrations, indoor alkene emission rates, and air exchange rates. Indoor hydroxyl radical concentrations decrease with increasing outdoor nitric oxide concentrations. Indoor temperature and indoor light intensity have moderate impacts on indoor hydroxyl radical concentrations. Outdoor hydroxyl radical concentrations, outdoor nitrate (NO 3rad ) radical concentrations, outdoor hydroperoxy radical concentrations, and hydroxyl radical removal by indoor surfaces are predicted to have no appreciable impact on indoor hydroxyl radical concentrations. Production of hydroxyl radicals in indoor environments appears to be controlled primarily by reactions of alkenes with ozone, and nitric oxide with hydroperoxy radical. Estimated indoor hydroxyl radical levels may potentially affect indoor air quality. Two examples are presented in which reactions of d-limonene and α-pinene with indoor hydroxyl radicals produce aldehydes, which may be of greater concern than the original compounds.

  12. Electron paramagnetic resonance and computational studies of radicals derived from boron-substituted N-heterocyclic carbene boranes.

    PubMed

    Walton, John C; Brahmi, Malika Makhlouf; Monot, Julien; Fensterbank, Louis; Malacria, Max; Curran, Dennis P; Lacôte, Emmanuel

    2011-07-01

    Fifteen second-generation NHC-ligated boranes with aryl and alkyl substituents on boron were prepared, and their radical chemistry was explored by electron paramagnetic resonance (EPR) spectroscopy and calculations. Hydrogen atom abstraction from NHC-BH(2)Ar groups produced boryl radicals akin to diphenylmethyl with spin extensively delocalized across the NHC, BH, and aryl units. All of the NHC-B·HAr radicals studied abstracted Br-atoms from alkyl bromides. Radicals with bulky N,N'-dipp substituents underwent dimerization about 2 orders of magnitude more slowly than first-generation NHC-ligated trihydroborates. The evidence favored head-to-head coupling yielding ligated diboranes. The first ligated diboranyl radical, with a structure intermediate between that of ligated diboranes and diborenes, was spectroscopically characterized during photolysis of di-t-butyl peroxide with N,N'-di-t-butyl-imidazol-2-ylidene phenylborane. The reactive site of B-alkyl-substituted NHC-boranes switched from the boron center to the alkyl substituent for both linear and branched alkyl groups. The β-borylalkyl radicals obtained from N,N'-dipp-substituted boranes underwent exothermic β-scissions with production of dipp-Imd-BH(2)· radicals and alkenes. The reverse additions of NHC-boryl radicals to alkenes are probably endothermic for alkyl-substituted alkenes, but exothermic for conjugated alkenes (addition of an NHC-boryl radical to 1,1-diphenylethene was observed). A cyclopropylboryl radical was observed, but, unlike other α-cyclopropyl-substituted radicals, this showed no propensity for ring-opening. PMID:21619055

  13. Free Radical Reactions in Food.

    ERIC Educational Resources Information Center

    Taub, Irwin A.

    1984-01-01

    Discusses reactions of free radicals that determine the chemistry of many fresh, processed, and stored foods. Focuses on reactions involving ascorbic acid, myoglobin, and palmitate radicals as representative radicals derived from a vitamin, metallo-protein, and saturated lipid. Basic concepts related to free radical structure, formation, and…

  14. Structure properties relationship in electrospun thermoset butyl rubber

    NASA Astrophysics Data System (ADS)

    Viriyabanthorn, Nantiya

    Development of breathable elastomeric membranes based upon butyl rubber (IIR) compounds was investigated. These semi-permeable membranes were produced by electrospinning the compounded butyl rubber under appropriate conditions. They were designed to be selectively permeable. Specifically, these elastomeric membranes allowed moisture vapor transport, while maintaining a barrier against liquid water. Additionally, the conductive nature of carbon black in the compounds was shown to allow greater control over membrane thickness than generally observed in electrospun fabrics. Data were presented to show that the excellent chemical resistance of butyl rubber to organic solvents and toxic agents was maintained despite the porous nature of the membranes. Air flow resistance could also be adjusted as functions of processing conditions which related to fiber diameter and porosity of the membrane. Mechanical properties, in addition to various transport properties, are compared to a butyl rubber baseline. The moisture vapor transport properties are compared to expanded PTFE films. The results demonstrate the effectiveness of thermoset elastomeric membranes for producing flexible, selectively permeable barriers. Moreover, It also shows the capability to produce nonwoven materials for applications requiring high elongation (stretch) and porosity. In most elastomer formulations, carbon black is used as filler because of its reinforcing properties. The addition of carbon was also found to be important in the electrospinning of butyl rubber. Carbon black typically results in improved mechanical properties for rubber compounds, however, its conductive properties can also play a role in the resulting fiber structure during the electrospinning process. Carbon black loadings were varied from 0, 25, 50, and 75 parts per hundred rubber (phr). Increased carbon black loading resulted in a larger process window and reduced density and bead formation. Tensile modulus (corrected for changes

  15. Intercalation of stable organic radicals into layered saponite clay.

    PubMed

    Hemme, Wilhelm L; Fujita, Wataru; Awaga, Kunio; Eckert, Hellmut

    2009-10-14

    2-(3- and 4-N-methylpyridinium)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl 3-N-oxide (abbreviated as m- and p-MPYNN), the butyl derivative (m- and p-BuPYNN), 4-(N-ethylammonium)-2,2,5,5-tetramethylpiperidin-1-oxyl (ETEP) and N,N,N',N'-Tetramethyl-1,4-phenylenediamine radical cation (TMPD(+)) have been successfully intercalated into saponite clay. The amount of intercalated material has been determined via UV/VIS spectroscopy, elemental analysis and EPR spectroscopy, and the expansion of the layer distance from approximately 12.0 to ca. 15 A has been measured by X-ray powder diffraction. The magnetic properties of these materials, which result from the interplay of the modified intermolecular interactions between the guest species, and the additional interaction with the host lattice, have been characterized by magnetic susceptibility, EPR and solid state NMR measurements. While the (29)Si and (27)Al NMR spectra show little influence of the radical species on the local structural environments of the nuclei in the host lattice, the guest-host interaction manifests itself in significant line-broadening and (in some cases) resonance displacements of the (1)H NMR signals belonging to the molecular radical cations. In the case of TMPD(+) intercalates, the NMR and EPR data indicate predominant radical dimerization within the interlayer space. PMID:19771362

  16. Chemistry of carotenoid neutral radicals.

    PubMed

    Ligia Focsan, A; Magyar, Adam; Kispert, Lowell D

    2015-04-15

    Proton loss from the carotenoid radical cations (Car(+)) to form neutral radicals (#Car) was investigated by numerous electrochemical, EPR, ENDOR and DFT studies described herein. The radical cation and neutral radicals were formed in solution electrochemically and stabilized on solid silica-alumina and MCM-41 matrices. Carotenoid neutral radicals were recently identified in Arabidopsis thaliana plant and photosystem II samples. Deprotonation at the terminal ends of a zeaxanthin radical cation could provide a secondary photoprotection pathway which involves quenching excited state chlorophyll by the long-lived zeaxanthin neutral radicals formed. PMID:25687648

  17. Conversion of Lignocellulosic Biomass to Ethanol and Butyl Acrylate

    SciTech Connect

    Binder, Thomas; Erpelding, Michael; Schmid, Josef; Chin, Andrew; Sammons, Rhea; Rockafellow, Erin

    2015-04-10

    Conversion of Lignocellulosic Biomass to Ethanol and Butyl Acrylate. The purpose of Archer Daniels Midlands Integrated Biorefinery (IBR) was to demonstrate a modified acetosolv process on corn stover. It would show the fractionation of crop residue to distinct fractions of cellulose, hemicellulose, and lignin. The cellulose and hemicellulose fractions would be further converted to ethanol as the primary product and a fraction of the sugars would be catalytically converted to acrylic acid, with butyl acrylate the final product. These primary steps have been demonstrated.

  18. N-Butyl-4-butyl­imino-2-methyl­pentan-2-aminium (E)-quercetinate

    PubMed Central

    Grosu, Ioana-Georgeta; Borodi, Gheorghe; Pop, Mihaela Maria

    2012-01-01

    The title salt, C14H31N2 +·C15H9O7 −, was obtained in the reaction of quercetin with n-butyl­amine in a mixture of acetone and hexane. The crystal structure determination shows that the quercetin donates one of its phenol H atoms to the N-butyl-4-butyl­imino-2-methyl­pentan-2-amine mol­ecule. The crystal structure of the salt is stabilized by intramolecular (N—H⋯N for the cation and O—H⋯O for the anion) and intermolecular hydrogen bonding (N—H⋯O between cation–anion pairs and O—H⋯O between anions). Quercetin molecules form dimers connected into a two-dimensional network. The dihedral angle between the quercetin ring systems is 19.61 (8)°. PMID:22904895

  19. 40 CFR 180.576 - Cyhalofop-butyl; tolerances for residues.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... of cyhalofop-butyl, including its metabolites and degradates, in or on the commodities listed in the... cyhalofop butyl , cyhalofop acid , and the di-acid metabolite . Commodity Parts per million Rice, grain...

  20. 40 CFR 180.576 - Cyhalofop-butyl; tolerances for residues.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... of cyhalofop-butyl, including its metabolites and degradates, in or on the commodities listed in the... cyhalofop butyl , cyhalofop acid , and the di-acid metabolite . Commodity Parts per million Rice, grain...

  1. 40 CFR 180.576 - Cyhalofop-butyl; tolerances for residues.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... of cyhalofop-butyl, including its metabolites and degradates, in or on the commodities listed in the... cyhalofop butyl , cyhalofop acid , and the di-acid metabolite . Commodity Parts per million Rice, grain...

  2. Recycling of gamma irradiated inner tubes in butyl based rubber compounds

    NASA Astrophysics Data System (ADS)

    Karaağaç, Bağdagül; Şen, Murat; Deniz, Veli; Güven, Olgun

    2007-12-01

    Recycling of gamma irradiated inner tubes made of butyl rubber in butyl based rubber compounds was studied. Gamma irradiated inner tube wastes and commercial butyl rubber crumbs devulcanized by conventional methods were replaced with butyl rubber up to 15 phr in the compound recipe. The rheological and mechanical properties and carbon black dispersion degree for both types of compounds were measured and then compared to those of virgin butyl rubber compound. It is well known that mechanical properties are deteriorated when rubber crumb is added to the virgin compound. The deterioration in the mechanical properties for the compounds prepared by recycling of irradiated inner tubes at 120 kGy is much lower than the compounds prepared by using commercial butyl crumbs. It has been observed that gamma irradiated used inner tubes were compatible with butyl rubber and could be recycled within butyl based rubber compounds.

  3. Roles of tert-butyl formate, tert-butyl alcohol and acetone in the regulation of methyl tert-butyl ether degradation by Mycobacterium austroafricanum IFP 2012.

    PubMed

    François, A; Garnier, L; Mathis, H; Fayolle, F; Monot, F

    2003-08-01

    Mycobacterium austroafricanum IFP 2012 is a Gram-positive strain able to grow on methyl tert-butyl ether (MTBE) as a sole carbon and energy source. The effect of two downstream metabolites of MTBE, tert-butyl formate (TBF) and tert-butyl alcohol (TBA) on MTBE degradation was investigated using resting cells. The addition of low concentrations of TBF decreased the MTBE degradation rate by about 30%. In contrast, the addition of TBA did not have a significant effect on MTBE degradation rate, even at high concentrations; and it was also shown that TBA degradation occurred only once MTBE was exhausted. At neutral pH, TBF hydrolysis involved mainly an esterase-type activity regulated by the presence of TBA. The TBF degradation rate was about four times lower than the MTBE degradation rate. Furthermore, acetone was identified as an intermediate during TBA degradation. An acetone mono-oxygenase activity, inhibited by methimazole but not by acetylene, was suggested. It was different from the MTBE/TBA mono-oxygenase and, thus, acetone did not appear to compete with MTBE and TBA for the same enzyme. These new results show that the metabolic regulation of the early steps of MTBE degradation by M. austroafricanum IFP 2012 is complex, involving inhibition and competition phenomena. PMID:12883872

  4. 27 CFR 21.100 - n-Butyl alcohol.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false n-Butyl alcohol. 21.100 Section 21.100 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants §...

  5. 27 CFR 21.100 - n-Butyl alcohol.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false n-Butyl alcohol. 21.100 Section 21.100 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants §...

  6. 27 CFR 21.101 - tert-Butyl alcohol.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false tert-Butyl alcohol. 21.101 Section 21.101 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants §...

  7. 27 CFR 21.100 - n-Butyl alcohol.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false n-Butyl alcohol. 21.100 Section 21.100 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants §...

  8. 27 CFR 21.100 - n-Butyl alcohol.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false n-Butyl alcohol. 21.100 Section 21.100 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants §...

  9. 27 CFR 21.100 - n-Butyl alcohol.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false n-Butyl alcohol. 21.100 Section 21.100 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants §...

  10. 27 CFR 21.101 - tert-Butyl alcohol.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false tert-Butyl alcohol. 21.101 Section 21.101 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants §...

  11. 27 CFR 21.101 - tert-Butyl alcohol.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false tert-Butyl alcohol. 21.101 Section 21.101 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants §...

  12. 21 CFR 172.270 - Sulfated butyl oleate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Coatings, Films and Related Substances...-butanol. Following sulfation, the reaction mixture is washed with water and neutralized with aqueous sodium or potassium hydroxide. Prior to sulfation, the butyl oleate reaction mixture meets the...

  13. 21 CFR 172.270 - Sulfated butyl oleate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN... transesterification of an edible vegetable oil using 1-butanol. Following sulfation, the reaction mixture is washed... oleate reaction mixture meets the following specifications: (1) Not less than 90 percent butyl oleate....

  14. 21 CFR 172.270 - Sulfated butyl oleate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN... transesterification of an edible vegetable oil using 1-butanol. Following sulfation, the reaction mixture is washed... oleate reaction mixture meets the following specifications: (1) Not less than 90 percent butyl oleate....

  15. 21 CFR 172.270 - Sulfated butyl oleate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN... transesterification of an edible vegetable oil using 1-butanol. Following sulfation, the reaction mixture is washed... oleate reaction mixture meets the following specifications: (1) Not less than 90 percent butyl oleate....

  16. 21 CFR 172.270 - Sulfated butyl oleate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION... edible vegetable oil using 1-butanol. Following sulfation, the reaction mixture is washed with water and neutralized with aqueous sodium or potassium hydroxide. Prior to sulfation, the butyl oleate reaction...

  17. 76 FR 59906 - Fluazifop-P-butyl; Pesticide Tolerances

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-28

    ... Performance Liquid Chromatography/Ultra-Violet Spectrometry (HPLC/UV)) is available to enforce the tolerance... of fluazifop-P-butyl in or on cotton, gin byproducts; cotton, refined oil; and cotton, undelinted... Tolerance In the Federal Register of December 15, 2010 (75 FR 78240) (FRL- 8853-1), EPA issued a...

  18. Recombination of Photogenerated Lophyl Radicals in Imidazolium-Based Ionic Liquids

    SciTech Connect

    Strehmel, V.; Wishart, J.; Polyansky, D.E.; Strehmel, B.

    2009-10-20

    Laser flash photolysis is applied to study the recombination reaction of lophyl radicals in ionic liquids in comparison with dimethylsulfoxide as an example of a traditional organic solvent. The latter exhibits a similar micropolarity as the ionic liquids. The ionic liquids investigated are 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (1), 1-hexyl-3-methylimidazolium hexafluorophosphate (2), and 1-butyl-3-methylimidazolium tetafluoroborate (3). The recombination of the photolytic generated lophyl radicals occur significantly faster in the ionic liquids than expected from their macroscopic viscosities and is a specific effect of these ionic liquids. On the other hand, this reaction can be compared with the macroscopic viscosity in the case of dimethylsulfoxide. Activation parameters obtained for lophyl radical recombination suggest different, anion-dependent mechanistic effects. Quantum chemical calculations based on density functional theory provide a deeper insight of the molecular properties of the lophyl radical and its precursor. Thus, excitation energies, spin densities, molar volumes, and partial charges are calculated. Calculations show a spread of spin density over the three carbon atoms of the imidazolyl moiety, while only low spin density is calculated for the nitrogens.

  19. [Aging and free radicals].

    PubMed

    Manso, C

    1992-02-01

    Several theories on aging are presented. All of them give important contributions but none explains all the aspects of the problem. Oxygen radicals produced during cellular combustion contribute to aging through multiple cumulative microlesions throughout life. The importance of glucose is emphasized; it forms early and late Maillard compounds. Other causes of aging are discussed. PMID:1595373

  20. Radical School Reform.

    ERIC Educational Resources Information Center

    Gross, Beatrice, Ed.; Gross, Ronald, Ed.

    This book provides a comprehensive examination of the nature of the school crisis and the ways in which radical thinkers and educators are dealing with it. Excerpts from the writings of Jonathan Kozol, John Holt, Kenneth Clark, and others are concerned with the realities of education in ghettos and suburbs. Paul Goodman, Marshall McLuhan, Sylvia…

  1. Tyrosyl Radicals in Dehaloperoxidase

    PubMed Central

    Dumarieh, Rania; D'Antonio, Jennifer; Deliz-Liang, Alexandria; Smirnova, Tatyana; Svistunenko, Dimitri A.; Ghiladi, Reza A.

    2013-01-01

    Dehaloperoxidase (DHP) from Amphitrite ornata, having been shown to catalyze the hydrogen peroxide-dependent oxidation of trihalophenols to dihaloquinones, is the first oxygen binding globin that possesses a biologically relevant peroxidase activity. The catalytically competent species in DHP appears to be Compound ES, a reactive intermediate that contains both a ferryl heme and a tyrosyl radical. By simulating the EPR spectra of DHP activated by H2O2, Thompson et al. (Thompson, M. K., Franzen, S., Ghiladi, R. A., Reeder, B. J., and Svistunenko, D. A. (2010) J. Am. Chem. Soc. 132, 17501–17510) proposed that two different radicals, depending on the pH, are formed, one located on either Tyr-34 or Tyr-28 and the other on Tyr-38. To provide additional support for these simulation-based assignments and to deduce the role(s) that tyrosyl radicals play in DHP, stopped-flow UV-visible and rapid-freeze-quench EPR spectroscopic methods were employed to study radical formation in DHP when three tyrosine residues, Tyr-28, Tyr-34, and Tyr-38, were replaced either individually or in combination with phenylalanines. The results indicate that radicals form on all three tyrosines in DHP. Evidence for the formation of DHP Compound I in several tyrosine mutants was obtained. Variants that formed Compound I showed an increase in the catalytic rate for substrate oxidation but also an increase in heme bleaching, suggesting that the tyrosines are necessary for protecting the enzyme from oxidizing itself. This protective role of tyrosines is likely an evolutionary adaptation allowing DHP to avoid self-inflicted damage in the oxidative environment. PMID:24100039

  2. Metabolism of ethanol to the 1-hydroxyethyl radical by rat heart microsomes

    SciTech Connect

    Reinke, L.A.; Rau, J.M.; Lai, E.K.; McCay, P.B. )

    1989-02-09

    Sarcoplasmic reticulum fractions were isolated from rat heart homogenates by differential centrifugation. The membrane fractions were incubated with ethanol (50 mM), an NADPH-generating system, and either 5,5-dimethyl-1-pyrroline N-oxide (DMPO) or N-t-butyl-phenylnitrone (PBN) as spin-trapping agents. Benzene extracts of the reactions were analyzed by electron spin resonance spectroscopy. The rat heart microsomes metabolized ethanol to a carbon-centered radical which formed adducts with both DMPO and PBN. When the experiments were performed with 1-{sup 13}C-ethanol, the spectra were split by the additional spin of the {sup 13}C, which demonstrates that the radical which had been trapped was the 1-hydroxyethyl radical. Heat inactivation of the microsomes resulted in loss of the signal. When the NAPH-generating system was replaced with NADH (1 mM), the intensity of the radical signal decreased by more than 50%. The intensity of the 1-hydroxyethyl radical was increased by more than two-fold by the addition of ADP-Fe{sup +3} or sodium azide, suggesting that iron-catalyzed formation of oxygen radicals may participate in the conversion of ethanol to a free radical under these conditions.

  3. Quantitative methods for studying the role of free radicals in biology

    NASA Astrophysics Data System (ADS)

    Jakus, Judit; Kriska, Tamas; Maximova, Tatjana K.; Nemeth, Andras; Korecz, Laszlo; Gal, Dezso

    1999-02-01

    The mechanism of the primary sensitization steps in Photodynamic Therapy could be of essential importance concerning the efficiency of the treatment. Besides the well known mechanisms there is a possibility that the interaction between the excited triplet state sensitizer and the doublet state free radicals generated by the cells adds a significant contribution to the overall photodynamic effect. To support this hypothesis the quantification and identification of free radicals would be required. For this purpose chemiluminescence studies and spin trapping seemed to be the most suitable methods due to the extremely short lifetime of free radicals in biological systems. We present data on the kinetics of accumulation of free radicals: (1) by measuring luminol- dependent chemiluminescence of stimulated macrophages both in the absence and in the presence of a free radical inhibitor 3,5 di-tert-butyl-4-hydroxyphenyl propionic acid; (2) by following the production of primary, secondary and tertiary radical adducts using DMPO (5,5-dimethyl-1-pyrroline N-oxide) as spin trapping agent in chemical model systems. The measured data are used to determine the effect of the excited sensitizers on the kinetics of accumulation of free radicals under biological conditions. These results would serve to design new and more effective sensitizers used for therapy based on the triplet-doublet mechanism of action.

  4. EPR Spin Trapping of an Oxalate-Derived Free Radical in the Oxalate Decarboxylase Reaction

    PubMed Central

    Imaram, Witcha; Saylor, Benjamin T.; Centonze, Christopher P.; Richards, Nigel G. J.; Angerhofer, Alexander

    2011-01-01

    EPR spin trapping experiments on bacterial oxalate decarboxylase from Bacillus subtilis under turn-over conditions are described. The use of doubly 13C-labeled oxalate leads to a characteristic splitting of the observed radical adducts using the spin trap N-tert-butyl-α-phenylnitrone linking them directly to the substrate. The radical was identified as the carbon dioxide radical anion which is a key intermediate in the hypothetical reaction mechanism of both decarboxylase and oxidase activities. X-ray crystallography had identified a flexible loop, SENS161-4, which acts as a lid to the putative active site. Site directed mutagenesis of the hinge amino acids, S161 and T165 was explored and showed increased radical trapping yields compared to the wild type. In particular, T165V shows approximately ten times higher radical yields while at the same time its decarboxylase activity was reduced by about a factor of ten. This mutant lacks a critical H-bond between T165 and R92 resulting in compromised control over its radical chemistry allowing the radical intermediate to leak into the surrounding solution. PMID:21277974

  5. Mechanistic investigation of oxidative Mannich reaction with tert-butyl hydroperoxide. The role of transition metal salt.

    PubMed

    Ratnikov, Maxim O; Doyle, Michael P

    2013-01-30

    A general mechanism is proposed for transition metal-catalyzed oxidative Mannich reactions of N,N-dialkylanilines with tert-butyl hydroperoxide (TBHP) as the oxidant. The mechanism consists of a rate-determining single electron transfer (SET) that is uniform from 4-methoxy- to 4-cyano-N,N-dimethylanilines. The tert-butylperoxy radical is the major oxidant in the rate-determining SET step that is followed by competing backward SET and irreversible heterolytic cleavage of the carbon-hydrogen bond at the α-position to nitrogen. A second SET completes the conversion of N,N-dimethylaniline to an iminium ion that is subsequently trapped by the nucleophilic solvent or the oxidant prior to formation of the Mannich adduct. The general role of Rh(2)(cap)(4), RuCl(2)(PPh(3))(3), CuBr, FeCl(3), and Co(OAc)(2) in N,N-dialkylaniline oxidations by T-HYDRO is to initiate the conversion of TBHP to tert-butylperoxy radicals. A second pathway, involving O(2) as the oxidant, exists for copper, iron, and cobalt salts. Results from linear free-energy relationship (LFER) analyses, kinetic and product isotope effects (KIE and PIE), and radical trap experiments of N,N-dimethylaniline oxidation by T-HYDRO in the presence of transition metal catalysts are discussed. Kinetic studies of the oxidative Mannich reaction in methanol and toluene are also reported. PMID:23298175

  6. The carbomethylation of arylacrylamides leading to 3-ethyl-3-substituted indolin-2-one by cascade radical addition/cyclization.

    PubMed

    Dai, Qiang; Yu, Jintao; Jiang, Yan; Guo, Songjin; Yang, Haitao; Cheng, Jiang

    2014-04-14

    An FeCl2-promoted carbomethylation of arylacrylamides by di-tert-butyl peroxide (DTBP) is achieved, leading to 3-ethyl-3-substituted indolin-2-one in high yield. The reaction tolerates a series of functional groups, such as cyano, nitro, ethyloxy carbonyl, bromo, chloro, and trifluoromethyl groups. The radical methylation and arylation of the alkenyl group are involved in this reaction. PMID:24589915

  7. Shock tube study of the reactions of the hydroxyl radical with combustion species and pollutants. Final report

    SciTech Connect

    Cohen, N.; Koffend, J.B.

    1998-02-01

    Shock heating t-butyl hydroperoxide behind a reflected shock wave has proved to be as a convenient source of hydroxyl radicals at temperatures near 1000 K. We applied this technique to the measurement of reaction rate coefficients of OH with several species of interest in combustion chemistry, and developed a thermochemical kinetics/transition state theory (TK-TST) model for predicting the temperature dependence of OH rate coefficients.

  8. Radical Compatibility with Nonaqueous Electrolytes and Its Impact on an All-Organic Redox Flow Battery

    SciTech Connect

    Wei, Xiaoliang; Xu, Wu; Huang, Jinhua; Zhang, Lu; Walter, Eric D.; Lawrence, Chad W.; Vijayakumar, M.; Henderson, Wesley A.; Liu, Tianbiao L.; Cosimbescu, Lelia; Li, Bin; Sprenkle, Vincent L.; Wang, Wei

    2015-07-20

    Nonaqueous redox flow batteries hold the promise to achieve higher energy density ascribed to the broader voltage window than their aqueous counterparts, but their current performance is limited by low redox material concentration, poor cell efficiency, and inferior cycling stability. We report a new nonaqueous total-organic flow battery based on high concentrations of 9-fluorenone as negative and 2,5-di-tert-butyl-1-methoxy-4-[2’-methoxyethoxy]benzene as positive redox materials. The supporting electrolytes are found to greatly affect the cycling stability of flow cells through varying chemical stabilities of the charged radical species, especially the 9-fluorenone radical anions, as confirmed by electron spin resonance. Such an electrolyte optimization sheds light on mechanistic understandings of capacity fading in flow batteries employing organic radical-based redox materials and demonstrates that rational design of supporting electrolyte is vital for stable cyclability.

  9. Free Radical Scavenging and Analgesic Activities of Cucumis sativus L. Fruit Extract

    PubMed Central

    Kumar, D; Kumar, S; Singh, J; Narender; Rashmi; Vashistha, BD; Singh, N

    2010-01-01

    The aqueous fruit extract of Cucumis sativus L. was screened for free radical scavenging and analgesic activities. The extract was subjected to in vitro antioxidant studies at 250 and 500 μg/ml and analgesic study at the doses 250 and 500 mg/kg, respectively. The free radical scavenging was compared with ascorbic acid, BHA (Butylated hydroxyl anisole), whereas, the analgesic effect was compared with Diclofenac sodium (50 mg/kg). The C. sativus fruit extract showed maximum antioxidant and analgesic effect at 500 μg/ml and 500 mg/kg, respectively. The presence of flavonoids and tannins in the extract as evidenced by preliminary phytochemical screening suggests that these compounds might be responsible for free radical scavenging and analgesic effects. PMID:21264095

  10. Toward Radicalizing Community Service Learning

    ERIC Educational Resources Information Center

    Sheffield, Eric C.

    2015-01-01

    This article advocates a radicalized theoretical construction of community service learning. To accomplish this radicalization, I initially take up a discussion of traditional understandings of CSL rooted in pragmatic/progressive thought. I then suggest that this traditional structural foundation can be radicalized by incorporating Deborah…

  11. In vitro radical scavenging activity of two Columbian Magnoliaceae

    NASA Astrophysics Data System (ADS)

    Puertas M., Miguel A.; Mesa v., Ana M.; Sáez v., Jairo A.

    2005-08-01

    The recent interest in the conservation of the tropical forest is due, at least in part, to the potential economic and health benefits that can be exploited from several plants. This report shows the in vitro antioxidant activity of some fractions isolated from leaves of two Columbian Magnoliaceae, Talauma hernandezii G. Lozano-C and Dugandiodendron yarumalense Lozano. The activity was determined using the radical monocation 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS·+) and the stable free radical 2-2-diphenyl-1-picrylhydrazyl (DPPH·), as part of general biological screening of these plants. The antioxidant capacity obtained from fractions was similar to those of α-tocopherol, tert-butylated hydroxyanisole (BHA), and ascorbic acid. The most active scavenger extract was the fraction 7 (TAA = 48.6 mmol Trolox/kg extract and IC50 ≤ 0.01 kg extract/mmol DPPH); and the least active was the fraction 1 (TAA = 11.23 mmol Trolox/kg extract and IC50 = 0.21 kg extract/mmol DPPH) all of them isolated from D. yarumalense. These results suggest that these plants can be attractive as source of antioxidant compounds with the ability to reduce radicals like ATBS and DPPH.

  12. 13 ENDOR studies of organic radicals in natural isotopic abundance

    NASA Astrophysics Data System (ADS)

    Kirste, Burkhard

    13C ENDOR studies of phenoxyls, galvinoxyls, triphenylmethyl radicals, nitroxides, and cyclosilane and semiquinone radical anions with natural isotopic distribution are reported. The method is described, and it is shown that 13C coupling constants can be measured precisely; in favorable cases even the determination of signs is possible by general TRIPLE resonance. Studies of the relaxation behavior of 13C ENDOR signals or measurements of hyperfine shifts in liquid-crystalline solutions yield information about dipolar hyperfine interactions and hence π spin populations which is of aid in assignments to molecular positions. Complete sets of 13C coupling constants have been determined for 2,4,6-tri- tert-butylphenoxyl and Coppinger's radical. For the central carbon atoms of tert-butyl groups, a Q parameter of Qτ-Bu C = -34 MHz is proposed, and for a 29Si atom in trimethylsilyl groups, QTMSSi = +49 MHz. Favorable conditions for natural-abundance 13C ENDOR experiments, e.g., small hyperfine anisotropies and use of deuterated compounds, and limitations of the method are discussed.

  13. Chitosan-graft-poly(n-butyl acrylate) copolymer: Synthesis and characterization of a natural/synthetic hybrid material.

    PubMed

    Anbinder, Pablo; Macchi, Carlos; Amalvy, Javier; Somoza, Alberto

    2016-07-10

    Two chitosan polymers with different deacetylation degree and molecular weight were subjected to grafting reactions with the aim to enhance the properties of these bio-based materials. Specifically, n-butyl acrylate in different proportions was grafted onto two different deacetylation degree (DD%) chitosan using radical initiation in a surfactant free emulsion system. Infrared spectroscopy was used to confirm grafting and products grafting percentage and efficiency were evaluated against acrylate/chitosan ratio and DD%. Thermal and structural properties and the behavior against water of the raw and grafted biopolymers were studied using several experimental techniques: differential scanning calorimetry, transmission electron microscopy, dynamic light scattering, water swelling, contact angle and positron annihilation lifetime spectroscopy. The influence of the grafting process on the morphological and physicochemical properties of the prepared natural/synthetic hybrid materials is discussed. PMID:27106155

  14. Free radical explosive composition

    DOEpatents

    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.

  15. Free radical propulsion concept

    NASA Technical Reports Server (NTRS)

    Hawkins, C. E.; Nakanishi, S.

    1981-01-01

    The concept of a free radical propulsion system, utilizing the recombination energy of dissociated low molecular weight gases to produce thrust, is analyzed. The system, operating at a theoretical impulse with hydrogen, as high as 2200 seconds at high thrust to power ratio, is hypothesized to bridge the gap between chemical and electrostatic propulsion capabilities. A comparative methodology is outlined by which characteristics of chemical and electric propulsion for orbit raising mission can be investigated. It is noted that free radicals proposed in rockets previously met with difficulty and complexity in terms of storage requirements; the present study proposes to eliminate the storage requirements by using electric energy to achieve a continuous-flow product of free radicals which are recombined to produce a high velocity propellant. Microwave energy used to dissociate a continuously flowing gas is transferred to the propellant via three-body-recombination for conversion to propellant kinetic energy. Microwave plasma discharge was found in excess of 90 percent over a broad range of pressure in preliminary experiments, and microwave heating compared to electrothermal heating showed much higher temperatures in gasdynamic equations.

  16. Laparoscopic radical cystectomy

    PubMed Central

    Fergany, Amr

    2012-01-01

    Objective Laparoscopic radical cystectomy (LRC) has emerged as a minimally invasive alternative to open radical cystectomy (ORC). This review focuses on patient selection criteria, technical aspects and postoperative outcomes of LRC. Methods Material for the review was obtained by a PubMed search over the last 10 years, using the keywords ‘laparoscopic radical cystectomy’ and ‘laparoscopic bladder cancer’ in human subjects. Results Twenty-two publications selected for relevance and content were used for this review from the total search yield. The level of evidence was IIb and III. LRC results in comparable short- and intermediate-range oncological outcomes to ORC, with generally longer operative times but decreased blood loss, postoperative pain and hospital stay. Overall operative and postoperative morbidity are equivalent. Conclusion In experienced hands, LRC is an acceptable minimally invasive alternative to ORC in selected patients, with the main advantage of decreased blood loss and postoperative pain, as well as a shorter hospital stay and recovery. PMID:26558003

  17. THERMOCHEMISTRY OF HYDROCARBON RADICALS

    SciTech Connect

    Kent M. Ervin, Principal Investigator

    2004-08-17

    Gas phase negative ion chemistry methods are employed to determine enthalpies of formation of hydrocarbon radicals that are important in combustion processes and to investigate the dynamics of ion-molecule reactions. Using guided ion beam tandem mass spectrometry, we measure collisional threshold energies of endoergic proton transfer and hydrogen atom transfer reactions of hydrocarbon molecules with negative reagent ions. The measured reaction threshold energies for proton transfer yield the relative gas phase acidities. In an alternative methodology, competitive collision-induced dissociation of proton-bound ion-molecule complexes provides accurate gas phase acidities relative to a reference acid. Combined with the electron affinity of the R {center_dot} radical, the gas phase acidity yields the RH bond dissociation energy of the corresponding neutral molecule, or equivalently the enthalpy of formation of the R{center_dot} organic radical, using equation: D(R-H) = {Delta}{sub acid}H(RH) + EA(R) - IE(H). The threshold energy for hydrogen abstraction from a hydrocarbon molecule yields its hydrogen atom affinity relative to the reagent anion, providing the RH bond dissociation energy directly. Electronic structure calculations are used to evaluate the possibility of potential energy barriers or dynamical constrictions along the reaction path, and as input for RRKM and phase space theory calculations. In newer experiments, we have measured the product velocity distributions to obtain additional information on the energetics and dynamics of the reactions.

  18. The millimeter-wave rotational spectrum of tertiary butyl isocyanide

    NASA Astrophysics Data System (ADS)

    Kisiel, Z.

    1992-02-01

    The millimeter-wave rotational spectrum of tertiary butyl isocyanide, (CH 3) 3CNC, was measured in the ground state and in the first excited state of the doubly degenerate CNC bending mode vβ. Accurate spectroscopic constants for both states have been determined from frequency measurements spanning the range 146-333 GHz. The results are compared with those for tertiary butyl cyanide, for which improved ground state sextic distortion constants are reported. The experimental quartic centrifugal distortion constants and the Coriolis coupling constant ξβ are well reproduced by a rudimentary force field calculation. Coriolis coupling constants for bending modes of linear segments attached to symmetric top C3 v molecules based on a tetrahedrally substituted carbon atom are compared and factors responsible for changes in their values are identified and discussed.

  19. Chronic pulmonary dysfunction following acute inhalation of butyl acrylate.

    PubMed

    Bhardwaj, Ravindra; Ducatman, Alan; Finkel, Mitchell S; Petsonk, Edward; Hunt, Janet; Beto, Robert J

    2012-01-01

    Butyl Acrylate (BA) (2-propionic acid; CH2 = CHCOOC4H9) is a colorless liquid commonly used in impregnation agents and adhesives. Dermal contact with BA has previously been reported to cause moderate skin irritation with skin sensitizing potential in humans. Health effects of inhalation of BA have not been previously reported. Accordingly, we document the health conditions of a bystander, first responder and landfill worker exposed to butyl acrylate (BA) released to the atmosphere following a collision and roadside spill in October 1998. Retrospective data were collected via chart review and analyzed for exposure, symptoms, physical findings and radiological, laboratory and spirometry results over a ten-year period. All three patients had similar respiratory symptoms including a dramatic hacking cough and dyspnea. Findings included abnormal pulmonary function tests and breath sounds. These data underscore the potential hazards of BA inhalational exposure and the need to wear additional protective equipment. PMID:23472539

  20. Room Temperature Aging Study of Butyl O-rings

    SciTech Connect

    Mark Wilson

    2009-08-07

    During testing under the Enhanced Surveillance Campaign in 2001, preliminary data detected a previously unknown and potentially serious concern with recently procured butyl o-rings. All butyl o-rings molded from a proprietary formulation throughout the period circa 1999 through 2001 had less than a full cure. Tests showed that sealing force values for these suspect o-rings were much lower than expected and their physical properties were very sensitive to further post curing at elevated temperatures. Further testing confirmed that these o-rings were approximately 50% cured versus the typical industry standard of > 90% cured. Despite this condition, all suspect o-rings fully conformed to their QC acceptance requirements, including their individual product drawing requirements.

  1. tert-Butyl Hydroperoxide Mediated Cascade Synthesis of 3-Arylsulfonylquinolines.

    PubMed

    Zhang, Liangliang; Chen, Su; Gao, Yuzhen; Zhang, Pengbo; Wu, Yile; Tang, Guo; Zhao, Yufen

    2016-03-18

    3-Arylsulfonylquinoline derivatives play important roles as pharmaceutical drugs. A new method for the synthesis of 3-arylsulfonylquinoline derivatives has been achieved through tert-butyl hydroperoxide mediated cycloaddition between N-propargyl aromatic amine derivatives and arylsulfonylhydrazides without the addition of any metals. This transformation offers a straightforward route to the formation of a C-S bond and quinoline ring in one step via a sulfonylation-cyclization-aromatization process. PMID:26959409

  2. Understanding the chemistry behind the antioxidant activities of butylated hydroxytoluene (BHT): a review.

    PubMed

    Yehye, Wageeh A; Rahman, Noorsaadah Abdul; Ariffin, Azhar; Abd Hamid, Sharifah Bee; Alhadi, Abeer A; Kadir, Farkaad A; Yaeghoobi, Marzieh

    2015-08-28

    Hindered phenols find a wide variety of applications across many different industry sectors. Butylated hydroxytoluene (BHT) is a most commonly used antioxidant recognized as safe for use in foods containing fats, pharmaceuticals, petroleum products, rubber and oil industries. In the past two decades, there has been growing interest in finding novel antioxidants to meet the requirements of these industries. To accelerate the antioxidant discovery process, researchers have designed and synthesized a series of BHT derivatives targeting to improve its antioxidant properties to be having a wide range of antioxidant activities markedly enhanced radical scavenging ability and other physical properties. Accordingly, some structure-activity relationships and rational design strategies for antioxidants based on BHT structure have been suggested and applied in practice. We have identified 14 very sensitive parameters, which may play a major role on the antioxidant performance of BHT. In this review, we attempt to summarize the current knowledge on this topic, which is of significance in selecting and designing novel antioxidants using a well-known antioxidant BHT as a building-block molecule. Our strategy involved investigation on understanding the chemistry behind the antioxidant activities of BHT, whether through hydrogen or electron transfer mechanism to enable promising anti-oxidant candidates to be synthesized. PMID:26150290

  3. Effects of di-n-butyl phthalate on the physiology and ultrastructure of cucumber seedling roots.

    PubMed

    Zhang, Ying; Tao, Yue; Sun, Guoqiang; Wang, Lei

    2014-05-01

    Agricultural pollution caused by the use of plastic sheetings has been documented to be a widespread problem in most of the major crop-planting regions of the world. In order to better understand the phytotoxic mechanisms induced by phthalic acid esters involved with this problem, Cucumber sativus L. cv Jinyan No. 4 were sown in pots to the three-leaf-stage in the presence of di-n-butyl phthalate (DBP; 0, 30, 50, 100, and 200 mg L(-1)) for 1, 3, 5, or 7 days. Physiology, biochemistry, and ultrastructure of seedling roots were examined. The results indicated that activities of three antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD)) were stimulated at low-DBP treatments and decreased under higher levels (>100 mg L(-1)) compared to the controls. On the other hand, SOD and POD provided a better defense against DBP-induced oxidative damage in the roots of cucumber seeding, compared to CAT. The productions of both malondialdehyde (MDA) and proline (Pro) were promoted under DBP stress. Visible impact on the cytoderm, mitochondrion, and vacuole was detected, possibly as a consequence of free radical generation. These results suggested that activation of the antioxidant system by DBP led to the formation of reactive oxygen species that resulted in cellular damage. PMID:24573460

  4. HIGH LEVELS OF MONOAROMATIC COMPOUNDS LIMIT THE USE OF SOLID-PHASE MICROEXTRACTION OF METHYL TERTIARY BUTYL ETHER AND TERTIARY BUTYL ALCOHOL

    EPA Science Inventory

    Recently, two papers reported the use of solid-phase microextraction (SPME) with polydimethylsiloxane(PDMS)/Carboxen fibers to determine trace levels of methyl tertiary butyl ether (MTBE) and tertiary butyl alcohol (tBA) in water. Attempts were made to apply this technique to th...

  5. Studies on the photolytic breakdown of hydroperoxides and peroxidized fatty acids by using electron spin resonance spectroscopy. Spin trapping of alkoxyl and peroxyl radicals in organic solvents.

    PubMed Central

    Davies, M J; Slater, T F

    1986-01-01

    Spin trapping using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) has been used to detect and distinguish between the carbon-centred, alkoxyl, and peroxyl radicals produced during the photolytic decomposition of hydroperoxides. Photolysis of tert-butyl and cumene hydroperoxides, and peroxidized fatty acids, in toluene, with low levels of u.v. light, is shown to lead to the initial production of alkoxyl radicals by homolysis of the oxygen-oxygen bond. Subsequent reaction of these radicals with excess hydroperoxide leads, by hydrogen abstraction, to the production of peroxyl radicals that can be detected as their corresponding adducts with the spin trap. Subsequent breakdown of these adducts produces alkoxyl radicals and a further species that is believed to be the oxidized spin-trap radical 5,5-dimethyl-1-pyrrolidone-2-oxyl. No evidence was obtained at low hydroperoxide concentrations, with either the cumene or lipid alkoxyl radicals, for the occurrence of beta-scission reactions; the production of low levels of carbon-centred radicals is believed to be due to the alternative reactions of hydrogen abstraction, ring closure, and/or 1,2 hydrogen shifts. Analogous experiments with 3,3,5,5-tetramethyl-1-pyrroline N-oxide (TMPO) led only to the trapping of alkoxyl radicals with no evidence for peroxyl radical adducts, this is presumably due to a decreased rate of radical addition because of increased steric hindrance. PMID:3030287

  6. Addition reaction of alkyl radical to C60 fullerene: Density functional theory study

    NASA Astrophysics Data System (ADS)

    Tachikawa, Hiroto; Kawabata, Hiroshi

    2016-02-01

    Functionalized fullerenes are known as a high-performance molecules. In this study, the alkyl-functionalized fullerenes (denoted by R-C60) have been investigated by means of the density functional theory (DFT) method to elucidate the effects of functionalization on the electronic states of fullerene. Also, the reaction mechanism of alkyl radicals with C60 was investigated. The methyl, ethyl, propyl, and butyl radicals (denoted by n = 1-4, where n means the number of carbon atoms in the alkyl radical) were examined as alkyl radicals. The DFT calculation showed that the alkyl radical binds to the carbon atom of C60 at the on-top site, and a strong C-C single bond is formed. The binding energies of alkyl radicals to C60 were distributed in the range of 31.8-35.1 kcal mol-1 at the CAM-B3LYP/6-311G(d,p) level. It was found that the activation barrier exists before alkyl addition, the barrier heights were calculated to be 2.1-2.8 kcal mol-1. The electronic states of R-C60 complexes were discussed on the basis of the theoretical results.

  7. Degradation of TAIC by water falling film dielectric barrier discharge--influence of radical scavengers.

    PubMed

    Rong, Shaopeng; Sun, Yabing

    2015-04-28

    This work describes the application of plasma generated by water falling film dielectric barrier discharge for the degradation of triallyl isocyanurate (TAIC). The results indicated that TAIC solution of 1000mg/L was effectively removed within 60min treatment at 120W output power. Six intermediates were identified and a possible evolution of the TAIC degradation process was continuously proposed basing on the results of mass spectrum analysis. The effects of metal ions and radical scavengers were investigated. Results showed that whatever hydrogen radical scavengers (carbon tetrachloride, perfluorooctane) or hydroxyl radical scavengers (iso-propyl alcohol, tert-butyl alcohol) all could further enhance the degradation processes, and both kings of radical scavengers could promote the generation of H2O2. In the present study, we employed a novel method by introducing the mixed additives of Fe(2+) and radical scavengers into the plasma. It was found that the reaction rate constant and energy efficiency were improved by 309.2% and 387.8%, respectively. Among the mixed additives, Fe(2+) could promote the decomposition and increase the oxidizing power of H2O2, which is generated from the plasma discharge and greatly enhanced by the radical scavengers. PMID:25668300

  8. Oxygen radicals in experimental shock: effects of spin-trapping nitrones in ameliorating shock pathophysiology (see comments)

    SciTech Connect

    Novelli, G.P. )

    1992-04-01

    Circulatory shock is accepted as a consequence of an acute oxygen radical overgeneration. Spin-trapping nitrones inactivate free radicals by forming relatively stable adducts. Three spin-trapping nitrones (N-tert-phenyl-butyl-nitrone; alpha-4-pyridyl-oxide-N-tert-butyl-nitrone; 5-5,dimethyl,1,pyrroline-N-oxide) were tested regarding their role in the pathophysiology and evolution of circulatory shock in rats. A prospective, randomized, controlled trial of spin-trapping nitrones in rats experiencing three different models of circulatory shock was designed. In the first group, endotoxic, traumatic, and mesenteric artery occlusion shock (all 100% lethal in control experiments) was prevented by the ip administration of N-tert-phenyl-butyl-nitrone (150 mg/kg); alpha-4-pyridyl-oxide-N-tert-butyl-nitrone (100 mg/kg); or 5-5,dimethyl,1,pyrroline-N-oxide (100 mg/kg). However, the evolution of shock was unaffected by the same compounds when all three nitrones had been previously inactivated by exposure to light and air. In the second group, microcirculatory derangements that were provoked by endotoxin and were observed in the mesocecum of rats were completely prevented by pretreatment with either peritoneal administration of each of the three nitrones or by their topical application to the microscopic field. While the rats survived after systemic treatment, those rats receiving topical nitrones died from endotoxic shock. In the third group, cell-membrane stiffness (a sign of peroxidative damage) was measured by spin-probes and electron-spin resonance in mitochondrial and microsomal membranes. Cell membranes obtained from shocked rats were more rigid than those membranes of controls. However, the membranes obtained from rats that were submitted to trauma or endotoxin after pretreatment with N-tert-phenyl-butyl-nitrone had normal stiffness.

  9. Oligorotaxane Radicals under Orders.

    PubMed

    Wang, Yuping; Frasconi, Marco; Liu, Wei-Guang; Sun, Junling; Wu, Yilei; Nassar, Majed S; Botros, Youssry Y; Goddard, William A; Wasielewski, Michael R; Stoddart, J Fraser

    2016-02-24

    A strategy for creating foldameric oligorotaxanes composed of only positively charged components is reported. Threadlike components-namely oligoviologens-in which different numbers of 4,4'-bipyridinium (BIPY(2+)) subunits are linked by p-xylylene bridges, are shown to be capable of being threaded by cyclobis(paraquat-p-phenylene) (CBPQT(4+)) rings following the introduction of radical-pairing interactions under reducing conditions. UV/vis/NIR spectroscopic and electrochemical investigations suggest that the reduced oligopseudorotaxanes fold into highly ordered secondary structures as a result of the formation of BIPY(•+) radical cation pairs. Furthermore, by installing bulky stoppers at each end of the oligopseudorotaxanes by means of Cu-free alkyne-azide cycloadditions, their analogous oligorotaxanes, which retain the same stoichiometries as their progenitors, can be prepared. Solution-state studies of the oligorotaxanes indicate that their mechanically interlocked structures lead to the enforced interactions between the dumbbell and ring components, allowing them to fold (contract) in their reduced states and unfold (expand) in their fully oxidized states as a result of Coulombic repulsions. This electrochemically controlled reversible folding and unfolding process, during which the oligorotaxanes experience length contractions and expansions, is reminiscent of the mechanisms of actuation associated with muscle fibers. PMID:27163033

  10. Oligorotaxane Radicals under Orders

    PubMed Central

    2016-01-01

    A strategy for creating foldameric oligorotaxanes composed of only positively charged components is reported. Threadlike components—namely oligoviologens—in which different numbers of 4,4′-bipyridinium (BIPY2+) subunits are linked by p-xylylene bridges, are shown to be capable of being threaded by cyclobis(paraquat-p-phenylene) (CBPQT4+) rings following the introduction of radical-pairing interactions under reducing conditions. UV/vis/NIR spectroscopic and electrochemical investigations suggest that the reduced oligopseudorotaxanes fold into highly ordered secondary structures as a result of the formation of BIPY•+ radical cation pairs. Furthermore, by installing bulky stoppers at each end of the oligopseudorotaxanes by means of Cu-free alkyne–azide cycloadditions, their analogous oligorotaxanes, which retain the same stoichiometries as their progenitors, can be prepared. Solution-state studies of the oligorotaxanes indicate that their mechanically interlocked structures lead to the enforced interactions between the dumbbell and ring components, allowing them to fold (contract) in their reduced states and unfold (expand) in their fully oxidized states as a result of Coulombic repulsions. This electrochemically controlled reversible folding and unfolding process, during which the oligorotaxanes experience length contractions and expansions, is reminiscent of the mechanisms of actuation associated with muscle fibers. PMID:27163033

  11. Radically innovative steelmaking technologies

    NASA Astrophysics Data System (ADS)

    Szekely, Julian

    1980-09-01

    The steel industry is faced with serious problems caused by the increasing cost of energy, labor and capital and by tough overseas competition, employing new highly efficient process plants. The very high cost of capital and of capital equipment renders the construction of new green field site plants, exemplifying the best available technology economically unattractive. For this reason, over the long term the development radically innovative steelmaking technologies appears to be the only satisfactory resolution of this dilemma. The purpose of this article is to present a critical review of some of the radically innovative steelmaking technologies that have been proposed during the past few years and to develop the argument that these indeed do deserve serious consideration at the present time. It should be stressed, however, that these innovative technologies can be implemented only as part of a carefully conceived long range plan, which contains as a subset short term solutions, such as trigger prices improved investment credits, and so forth and intermediate term solutions, such as more extensive use of continuous casting, external desulfurization and selective modernization in general.

  12. Radical-radical interactions among oxidized guanine bases including guanine radical cation and dehydrogenated guanine radicals.

    PubMed

    Zhao, Jing; Wang, Mei; Yang, Hongfang; Zhang, Meng; Liu, Ping; Bu, Yuxiang

    2013-09-19

    We present here a theoretical investigation of the structural and electronic properties of di-ionized GG base pairs (G(•+)G(•+),G(-H1)(•)G(•+), and G(-H1)(•)G(-H1)(•)) consisting of the guanine cation radical (G(•+)) and/or dehydrogenated guanine radical (G(-H1)(•)) using density functional theory calculations. Different coupling modes (Watson-Crick/WC, Hoogsteen/Hoog, and minor groove/min hydrogen bonding, and π-π stacking modes) are considered. We infer that a series of G(•+)G(•+) complexes can be formed by the high-energy radiation. On the basis of density functional theory and complete active space self-consistent (CASSCF) calculations, we reveal that in the H-bonded and N-N cross-linked modes, (G(•+)G(•+))WC, (G(-H1)(•)G(-H1)(•))WC, (G(-H1)(•)G(-H1)(•))minI, and (G(-H1)(•)G(-H1)(•))minIII have the triplet ground states; (G(•+)G(•+))HoogI, (G(-H1)(•)G(•+))WC, (G(-H1)(•)G(•+))HoogI, (G(-H1)(•)G(•+))minI, (G(-H1)(•)G(•+))minII, and (G(-H1)(•)G(-H1)(•))minII possess open-shell broken-symmetry diradical-characterized singlet ground states; and (G(•+)G(•+))HoogII, (G(•+)G(•+))minI, (G(•+)G(•+))minII, (G(•+)G(•+))minIII, (G(•+)G(•+))HoHo, (G(-H1)(•)G(•+))minIII, (G(-H1)(•)G(•+))HoHo, and (G(-H1)(•)G(-H1)(•))HoHo are the closed-shell systems. For these H-bonded diradical complexes, the magnetic interactions are weak, especially in the diradical G(•+)G(•+) series and G(-H1)(•)G(-H1)(•) series. The magnetic coupling interactions of the diradical systems are controlled by intermolecular interactions (H-bond, electrostatic repulsion, and radical coupling). The radical-radical interaction in the π-π stacked di-ionized GG base pairs ((G(•+)G(•+))ππ, (G(-H1)(•)G(•+))ππ, and (G(-H1)(•)G(-H1)(•))ππ) are also considered, and the magnetic coupling interactions in these π-π stacked base pairs are large. This is the first theoretical prediction that some di

  13. N-Butyl acrylate polymer composition for solar cell encapsulation and method

    NASA Technical Reports Server (NTRS)

    Gupta, Amitava (Inventor); Ingham, John D. (Inventor); Yavrouian, Andre H. (Inventor)

    1983-01-01

    A polymer syrup for encapsulating solar cell assemblies. The syrup includes uncrosslinked poly(n-butyl)acrylate dissolved in n-butyl acrylate monomer. Preparation of the poly(n-butyl)acrylate and preparation of the polymer syrup is disclosed. Methods for applying the polymer syrup to solar cell assemblies as an encapsulating pottant are described. Also included is a method for solar cell construction utilizing the polymer syrup as a dual purpose adhesive and encapsulating material.

  14. Enantioselective degradation and chiral stability of the herbicide fluazifop-butyl in soil and water.

    PubMed

    Qi, Yanli; Liu, Donghui; Luo, Mai; Jing, Xu; Wang, Peng; Zhou, Zhiqiang

    2016-03-01

    The stereoselective degradation and transformation of the enantiomers of the herbicide fluazifop-butyl in soil and water were studied to investigate the environmental behavior and chiral stability of the optical pure product. Its main chiral metabolite fluazifop was also monitored. LC/MS/MS with Chiralpak IC chiral column was used to separate the enantiomers of fluazifop-butyl and fluazifop. Validated enantioselective residue analysis methods were established with recoveries ranging from 77.1 to 115.4% and RSDs from 0.85 to 8.9% for the enantiomers. It was found the dissipation of fluazifop-butyl was rapid in the three studied soils (Beijing, Harbin and Anhui soil), and the degradation half-lives of the enantiomers ranged from 0.136 to 2.7 d. Enantioselective degradations were found in two soils. In Beijing soil, R-fluazifop-butyl was preferentially degraded leading to relative enrichment of S-enantiomer, but in Anhui soil, S-fluazifop-butyl dissipated faster. There was no conversion of the R-fluazifop-butyl into S-fluazifop-butyl or vice versa in the soils. The formation of fluazifop in the soils was rapidly accompanied with the fast degradation of fluazifop-butyl, and the enantioselectivity and the transformation of S-fluazifop to R-fluazifop were found. The degradation of fluazifop-butyl in water was also quick, with half-lives of the enantiomers ranging from 0.34 to 2.52 d, and there was no significant enantioselectivity of the degradation of fluazifop-butyl and the formation of fluazifop. The effects of pH on the degradation showed fluazifop-butyl enantiomers degraded faster in alkaline conditions. This study showed an evidence of enantioselective behavior and enantiomerization of the chiral herbicide fluazifop-butyl. PMID:26735732

  15. Oxygen radicals and renal diseases.

    PubMed

    Klahr, S

    1997-01-01

    Reactive oxygen metabolites (superoxide, hydrogen peroxide, hydroxyl radical, and hypochlorous acid) are important mediators of renal damage in acute renal failure and glomerular and tubulointerstitial diseases. The role of these oxygen metabolites in the above entities is discussed, and the effects of antioxidants and scavengers of O2 radicals are considered. The role of oxygen radicals in the regulation of gene transcription is also considered. PMID:9387104

  16. Inducing PLA/starch compatibility through butyl-etherification of waxy and high amylose starch.

    PubMed

    Wokadala, Obiro Cuthbert; Emmambux, Naushad Mohammad; Ray, Suprakas Sinha

    2014-11-01

    In this study, waxy and high amylose starches were modified through butyl-etherification to facilitate compatibility with polylactide (PLA). Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy and wettability tests showed that hydrophobic butyl-etherified waxy and high amylose starches were obtained with degree of substitution values of 2.0 and 2.1, respectively. Differential scanning calorimetry, tensile testing, and scanning electron microscopy (SEM) demonstrated improved PLA/starch compatibility for both waxy and high amylose starch after butyl-etherification. The PLA/butyl-etherified waxy and high amylose starch composite films had higher tensile strength and elongation at break compared to PLA/non-butyl-etherified composite films. The morphological study using SEM showed that PLA/butyl-etherified waxy starch composites had a more homogenous microstructure compared to PLA/butyl-etherified high amylose starch composites. Thermogravimetric analysis showed that PLA/starch composite thermal stability decreased with starch butyl-etherification for both waxy and high amylose starches. This study mainly demonstrates that PLA/starch compatibility can be improved through starch butyl-etherification. PMID:25129738

  17. Free radical propulsion concept

    NASA Technical Reports Server (NTRS)

    Hawkins, C. E.; Nakanishi, S.

    1981-01-01

    A free radical propulsion concept utilizing the recombination energy of dissociated low molecular weight gases to produce thrust was examined. The concept offered promise of a propulsion system operating at a theoretical impulse, with hydrogen, as high as 2200 seconds at high thrust to power ratio, thus filling the gas existing between chemical and electrostatic propulsion capabilities. Microwave energy used to dissociate a continuously flowing gas was transferred to the propellant via three body recombination for conversion to propellant kinetic energy. Power absorption by the microwave plasma discharge was in excess of 90 percent over a broad range of pressures. Gas temperatures inferred from gas dynamic equations showed much higher temperatures from microwave heating than from electrothermal heating. Spectroscopic analysis appeared to corroborate the inferred temperatures of one of the gases tested.

  18. Radicals in Berkeley?

    PubMed Central

    Linn, Stuart

    2015-01-01

    In a previous autobiographical sketch for DNA Repair (Linn, S. (2012) Life in the serendipitous lane: excitement and gratification in studying DNA repair. DNA Repair 11, 595–605), I wrote about my involvement in research on mechanisms of DNA repair. In this Reflections, I look back at how I became interested in free radical chemistry and biology and outline some of our bizarre (at the time) observations. Of course, these studies could never have succeeded without the exceptional aid of my mentors: my teachers; the undergraduate and graduate students, postdoctoral fellows, and senior lab visitors in my laboratory; and my faculty and staff colleagues here at Berkeley. I am so indebted to each and every one of these individuals for their efforts to overcome my ignorance and set me on the straight and narrow path to success in research. I regret that I cannot mention and thank each of these mentors individually. PMID:25713083

  19. Kinetics of the degradation of n-butyl benzyl phthalate using O₃/UV, direct photolysis, direct ozonation and UV effects.

    PubMed

    Lovato, María E; Gilliard, María B; Cassano, Alberto E; Martín, Carlos A

    2015-01-01

    The aim of this work is to study the degradation kinetics of the endocrine disruptor benzyl butyl phthalate using ozone and UV radiation. The model comprises four parallel subsystems that are identified and isolated: (1) direct photolysis, (2) direct ozonation in the absence of hydroxyl radicals, (3) complete ozonation (direct + indirect oxidation), and (4) ozone + UV. To determine the nature of ozone attacks and the influence of ·OH radicals on O3 activity, two sets of experiments were performed: (i) conventional ozonation and (ii) the same ozonation experiments in the presence of tert-butanol as radical scavenger, where only the reactions involving molecular ozone are present. The explored variables were (i) ozone concentration, (ii) incident radiation rate at the reactor windows, (iii) reaction pH, and (iv) the presence of radical scavengers. Major intermediates of BBP degradation were identified. Degradation kinetics was correctly modeled by a pseudo-second-order kinetic model based on the sum of all the effects occurring during the treatment. The corresponding kinetic constants were obtained, and the relative contributions of each of the considered subsystems were evaluated. PMID:24687792

  20. OKN-007 decreases free radical levels in a preclinical F98 rat glioma model.

    PubMed

    Coutinho de Souza, Patricia; Smith, Nataliya; Atolagbe, Oluwatomisin; Ziegler, Jadith; Njoku, Charity; Lerner, Megan; Ehrenshaft, Marilyn; Mason, Ronald P; Meek, Bill; Plafker, Scott M; Saunders, Debra; Mamedova, Nadezda; Towner, Rheal A

    2015-10-01

    Free radicals are associated with glioma tumors. Here, we report on the ability of an anticancer nitrone compound, OKN-007 [Oklahoma Nitrone 007; a disulfonyl derivative of α-phenyl-tert-butyl nitrone (PBN)] to decrease free radical levels in F98 rat gliomas using combined molecular magnetic resonance imaging (mMRI) and immunospin-trapping (IST) methodologies. Free radicals are trapped with the spin-trapping agent, 5,5-dimethyl-1-pyrroline N-oxide (DMPO), to form DMPO macromolecule radical adducts, and then further tagged by immunospin trapping by an antibody against DMPO adducts. In this study, we combined mMRI with a biotin-Gd-DTPA-albumin-based contrast agent for signal detection with the specificity of an antibody for DMPO nitrone adducts (anti-DMPO probe), to detect in vivo free radicals in OKN-007-treated rat F98 gliomas. OKN-007 was found to significantly decrease (P < 0.05) free radical levels detected with an anti-DMPO probe in treated animals compared to untreated rats. Immunoelectron microscopy was used with gold-labeled antibiotin to detect the anti-DMPO probe within the plasma membrane of F98 tumor cells from rats administered anti-DMPO in vivo. OKN-007 was also found to decrease nuclear factor erythroid 2-related factor 2, inducible nitric oxide synthase, 3-nitrotyrosine, and malondialdehyde in ex vivo F98 glioma tissues via immunohistochemistry, as well as decrease 3-nitrotyrosine and malondialdehyde adducts in vitro in F98 cells via ELISA. The results indicate that OKN-007 effectively decreases free radicals associated with glioma tumor growth. Furthermore, this method can potentially be applied toward other types of cancers for the in vivo detection of macromolecular free radicals and the assessment of antioxidants. PMID:26119786

  1. Gas-Phase Reactivity of Protonated 2-, 3-, and 4-Dehydropyridine Radicals Toward Organic Reagents

    NASA Astrophysics Data System (ADS)

    Adeuya, Anthony; Price, Jason M.; Jankiewicz, Bartłomiej J.; Nash, John J.; Kenttämaa, Hilkka I.

    2009-11-01

    To explore the effects of the electronic nature of charged phenyl radicals on their reactivity, reactions of the three distonic isomers of n-dehydropyridinium cation (n = 2, 3, or 4) have been investigated in the gas phase by using Fourier-transform ion cyclotron resonance mass spectrometry. All three isomers react with cyclohexane, methanol, ethanol, and 1-pentanol exclusively via hydrogen atom abstraction and with allyl iodide mainly via iodine atom abstraction, with a reaction efficiency ordering of 2 > 3 > 4. The observed reactivity ordering correlates well with the calculated vertical electron affinities of the charged radicals (i.e., the higher the vertical electron affinity, the faster the reaction). Charged radicals 2 and 3 also react with tetrahydrofuran exclusively via hydrogen atom abstraction, but the reaction of 4 with tetrahydrofuran yields products arising from nonradical reactivity. The unusual reactivity of 4 is likely to result from the contribution of an ionized carbene-type resonance structure that facilitates nucleophilic addition to the most electrophilic carbon atom (C-4) in this charged radical. The influence of such a resonance structure on the reactivity of 2 is not obvious, and this may be due to stabilizing hydrogen-bonding interactions in the transition states for this molecule. Charged radicals 2 and 3 abstract a hydrogen atom from the substituent in both phenol and toluene, but 4 abstracts a hydrogen atom from the phenyl ring, a reaction that is unprecedented for phenyl radicals. Charged radical 4 reacts with tert-butyl isocyanide mainly by hydrogen cyanide (HCN) abstraction, whereas CN abstraction is the principal reaction for 2 and 3. The different reactivity observed for 4 (as compared to 2 and 3) is likely to result from different charge and spin distributions of the reaction intermediates for these charged radicals.

  2. Radical Chemistry and Cytotoxicity of Bioreductive 3-Substituted Quinoxaline Di-N-Oxides.

    PubMed

    Anderson, Robert F; Yadav, Pooja; Shinde, Sujata S; Hong, Cho R; Pullen, Susan M; Reynisson, Jóhannes; Wilson, William R; Hay, Michael P

    2016-08-15

    The radical chemistry and cytotoxicity of a series of quinoxaline di-N-oxide (QDO) compounds has been investigated to explore the mechanism of action of this class of bioreductive drugs. A series of water-soluble 3-trifluoromethyl (4-10), 3-phenyl (11-19), and 3-methyl (20-21) substituted QDO compounds were designed to span a range of electron affinities consistent with bioreduction. The stoichiometry of loss of QDOs by steady-state radiolysis of anaerobic aqueous formate buffer indicated that one-electron reduction of QDOs generates radicals able to initiate chain reactions by oxidation of formate. The 3-trifluoromethyl analogues exhibited long chain reactions consistent with the release of the HO(•), as identified in EPR spin trapping experiments. Several carbon-centered radical intermediates, produced by anaerobic incubation of the QDO compounds with N-terminal truncated cytochrome P450 reductase (POR), were characterized using N-tert-butyl-α-phenylnitrone (PBN) and 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide (DEPMPO) spin traps and were observed by EPR. Experimental data were well simulated for the production of strongly oxidizing radicals, capable of H atom abstraction from methyl groups. The kinetics of formation and decay of the radicals produced following one-electron reduction of the parent compounds, both in oxic and anoxic solutions, were determined using pulse radiolysis. Back oxidation of the initially formed radical anions by molecular oxygen did not compete effectively with the breakdown of the radical anions to form oxidizing radicals. The QDO compounds displayed low hypoxic selectivity when tested against oxic and hypoxic cancer cell lines in vitro. The results from this study form a kinetic description and explanation of the low hypoxia-selective cytotoxicity of QDOs against cancer cells compared to the related benzotriazine 1,4-dioxide (BTO) class of compounds. PMID:27380897

  3. Gas-phase reactivity of protonated 2-, 3-, and 4-dehydropyridine radicals toward organic reagents.

    PubMed

    Adeuya, Anthony; Price, Jason M; Jankiewicz, Bartłomiej J; Nash, John J; Kenttämaa, Hilkka I

    2009-12-10

    To explore the effects of the electronic nature of charged phenyl radicals on their reactivity, reactions of the three distonic isomers of n-dehydropyridinium cation (n = 2, 3, or 4) have been investigated in the gas phase by using Fourier-transform ion cyclotron resonance mass spectrometry. All three isomers react with cyclohexane, methanol, ethanol, and 1-pentanol exclusively via hydrogen atom abstraction and with allyl iodide mainly via iodine atom abstraction, with a reaction efficiency ordering of 2 > 3 > 4. The observed reactivity ordering correlates well with the calculated vertical electron affinities of the charged radicals (i.e., the higher the vertical electron affinity, the faster the reaction). Charged radicals 2 and 3 also react with tetrahydrofuran exclusively via hydrogen atom abstraction, but the reaction of 4 with tetrahydrofuran yields products arising from nonradical reactivity. The unusual reactivity of 4 is likely to result from the contribution of an ionized carbene-type resonance structure that facilitates nucleophilic addition to the most electrophilic carbon atom (C-4) in this charged radical. The influence of such a resonance structure on the reactivity of 2 is not obvious, and this may be due to stabilizing hydrogen-bonding interactions in the transition states for this molecule. Charged radicals 2 and 3 abstract a hydrogen atom from the substituent in both phenol and toluene, but 4 abstracts a hydrogen atom from the phenyl ring, a reaction that is unprecedented for phenyl radicals. Charged radical 4 reacts with tert-butyl isocyanide mainly by hydrogen cyanide (HCN) abstraction, whereas CN abstraction is the principal reaction for 2 and 3. The different reactivity observed for 4 (as compared to 2 and 3) is likely to result from different charge and spin distributions of the reaction intermediates for these charged radicals. PMID:19902945

  4. Kinetics and mechanism of the thermal dissociation of O,O'-bis(1,3,5-TRI-tert-butyl-4-oxo-2,5-cyclo-hexadienyl)-p-benzoquinone dioxime in solution

    SciTech Connect

    Khizhnyi, V.A.; Danilova, T.A.; Goloverda, G.Z.; Dobronravova, Z.A.

    1987-09-20

    The kinetics and mechanism of the thermal dissociation of O,O'-bis(1,3,5-tri-tert-butyl-4-oxo-2,5-cyclohexadienyl)-p-benzoquinone dioxime (quinol ether) in solutions in nonpolar solvents were investigated. The dissociation of the quinol ether is reversible two-stage process and involves the formation of an intermediate radical. In relation to the reaction conditions (initial concentration, temperature) the dissociation rate of the quinol ether obeys the kinetic equations omega = k/sub eff/ x c/sup 1/2/ or omega = k/sub 1/c. The change in the reaction order is due to the ratio of the rates of dissociation of the intermediate radical and of its reaction with the phenoxyl radical. The ESR spectra were recorded on a Varian E-9 radiospectrometer with high-frequency modulation of 100 kHz.

  5. Radical scavenging activity and cytotoxicity of ferulic acid.

    PubMed

    Ogiwara, Takako; Satoh, Kazue; Kadoma, Yoshinori; Murakami, Yukio; Unten, Senwa; Atsumi, Toshiko; Sakagami, Hiroshi; Fujisawa, Seiichiro

    2002-01-01

    Ferulic acid and eugenol were examined for their superoxide (O2-), hydroxyl radical (.OH) and nitric oxide (NO)-scavenging ability, using ESR spectroscopy with spin trap agents DMPO and carboxy-PTIO/NOC-7. Ferulic acid more efficiently scavenged .OH and NO than eugenol. The O2- scavenging activity of ferulic acid was comparable with that of eugenol. Ferulic acid significantly reduced the NO production by lipopolysaccharide (LPS)-stimulated mouse macrophage-like cells (Raw 264.7 cells) compared to eugenol. The cytotoxic activity of ferulic acid against Raw 264.7 cells was comparable with that against human submandibular gland carcinoma (HSG) cells and the cytotoxicity of ferulic acid was about 10-fold smaller than that of eugenol. The stoichiometric factor (n) (number of moles of peroxy radical trapped by moles of the relevant phenol) of ferulic acid and eugenol was investigated, using the induction period methods of the methyl methacrylate polymerization system. The n-value of ferulic acid (1.5) was higher than that of eugenol (1.0) and was similar to that of 2, 6-di-t-butyl-4-methylphenol (BHT). Ferulic acid as well as eugenol may produce a dimer during the induction period due to an n-value less than 2. These results suggested that ferulic acid may be useful for preventing cell damage perhaps caused by O2-, and in particular by .OH and NO, in living systems. PMID:12529986

  6. Eosinophil peroxidase-dependent hydroxyl radical generation by human eosinophils.

    PubMed

    McCormick, M L; Roeder, T L; Railsback, M A; Britigan, B E

    1994-11-11

    Eosinophil production of superoxide (O2-.) and hydrogen peroxide (H2O2) is important in host defense. The present study assessed the potential of eosinophils to generate another potent cytotoxic species, the hydroxyl radical (.OH). .OH formation by phorbol myristate acetate (PMA)-stimulated eosinophils was demonstrated using an alpha-(4-pyridyl-1-oxide)-N-tert-butyl nitrone/ethanol spin trapping system. Additionally, .OH was spin trapped following the addition of purified eosinophil peroxidase (EPO) to a cell-free O2-./H2O2 generating systems. Effects of superoxide dismutase, catalase, azide, aminotriazole, chloride-depleted buffer, and extensive metal chelation were consistent with .OH formation via the reaction of O2-. and EPO-generated hypohalous acid. Under chloride-depleted conditions, physiologic concentrations of Br- increased .OH formation by both PMA-stimulated eosinophils and the cell-free EPO system. Physiologic concentrations of SCN-, however, did not increase .OH formation, and in the presence of both Br- and SCN-, .OH formation was similar to SCN- only. Eosinophils appear to form .OH via an EPO-dependent mechanism, the magnitude of which varies with the availability of various EPO substrates. Given the highly reactive nature of this radical and the ability of EPO to adhere to cell membranes, even small amounts of .OH formed at such sites could contribute to eosinophil-mediated cytotoxicity. PMID:7961724

  7. Preliminary studies on the activities of spin traps as scavengers of free radicals

    SciTech Connect

    Ogunbiyi, P.O.; Washington, I. )

    1991-03-15

    The spin trapping agents, N-t-Butyl-a-phenyl-nitrone (PBN) and 5,5-Dimethyl-1-pyroline-N-oxide (DMPO) have been used to investigate the primary free radicals involved in various tissue injuries. Also, PBN and DMPO can provide some protection against free radical-induced lung injuries. However, their therapeutic potentials as free radical scavengers remained unexamined. In this study, the effects of PBN and DMPO on guinea pig lung microsomal lipid peroxidation were investigated using thiobarbituric acid-reactive substance assay. Superoxide anions (O{sup 2}{minus}) were generated in an enzymatic and a non-enzymatic system. PBN and DMPO each, significantly inhibited NADPH-stimulated lipid peroxidation irrespective of the presence of Fe{sup 3+}. Cytochrome c reduction by the enzymatic and nitro blue tetrazolium reduction by the non-enzymatic O{sup 2}{minus} generating systems were both inhibited by PBN and DMPO as well as superoxide dismutase and dimethyl sulfoxide when compared with the controls. The spin traps exhibited lower potencies in these systems than the reference compounds, SOD and DMSO, which are well established as O{sup 2}{minus} and hydroxyl radical scavengers respectively. Results demonstrate the free radical scavenging properties of PBN and DMPO. This is an indication of their possible usefulness as antioxidants.

  8. Antisickling activity of butyl stearate isolated from Ocimum basilicum (Lamiaceae)

    PubMed Central

    Tshilanda, Dorothée Dinangayi; Mpiana, Pius Tshimankinda; Onyamboko, Damase Nguwo Vele; Mbala, Blaise Mavinga; Ngbolua, Koto-te-Nyiwa; Tshibangu, Damien Sha Tshibey; Bokolo, Matthieu Kokengo; Taba, Kalulu Muzele; Kasonga, Teddy Kabeya

    2014-01-01

    Objective To perform phytochemical analyses on the leaves of Ocimum basilicum L. (O. basilicum), to elucidate the structure of isolate and then perform the antisickling activity on the crude extract and on the isolate. Methods The Emmel test performed on the acidified methanolic extract of this plant was used to evaluate the antisickling activity. The structure characterization of the active compound was performed using chromatographic techniques for the separation and the spectroscopic ones for structure elucidation (1H-NMR, 13C-NMR, COSY, HMBC). Results The chemical screening on the crude extract revealed the presence of polyphenols (flavonoids, anthocyanins, leucoanthocyanins, tannins, quinones) alkaloids, saponins, triterpenoids and steroids. The obtained extract after evaporation yielded 34.50 g (11.5%) out of 300 g of powdered leaves of O. basilicum. The acidified methanolic extract and butyl stearate showed an interesting antisickling activity. Conclusions The acidified methanolic extract and butyl stearate from O. basilicum displayed a good antisickling activity. To the best of our knowledge, this is the first time to report the antisickling activity of this compound in this plant. The synthesized compound presented the same spectroscopic characteristics than the natural one and the antisickling activities of its derivatives are understudying. PMID:25182725

  9. The Rotational Spectrum of Tertiary-Butyl Alcohol

    NASA Astrophysics Data System (ADS)

    Cohen, E. A.; Drouin, B. J.; Valenzuela, E. A.; Woods, R. C.; Caminati, W.; Maris, A.; Melandri, S.

    2009-06-01

    Tertiary-butyl alcohol is a nearly spherical rotor for which the internal rotation axis of the t-butyl group is close to the c molecular axis in the ac plane. Methyl group torsional spittings are not observed in the ground state. Its 8 to 40 GHz rotational spectrum was reported at this meeting by Valenzuela and Woods in 1974 and in more detail in 1975. The parameters derived at that time from a fit to the E states with J,K≤ 20 have provided the basis for extending the measurements to > 500 GHz. The combined data set extends to J,K > 50 and is fit with the program SPFIT using a common set of parameters for both the A and E states. The general features of the spectrum and the fitting procedure will be described. The resulting molecular constants and their interpretation will be discussed. E.A. Valenzuela, and R. C. Woods, Abstract MF6, International Symposium on Molecular Spectroscopy, Columbus, OH, 1974 E.A. Valenzuela, and R. C. Woods, Abstract RG15, International Symposium on Molecular Spectroscopy, Columbus, OH, 1975 E.A. Valenzuela, Ph.D. Thesis, University of Wisconsin-Madison, 1975. H. M. Pickett, J. Mol. Spectrosc. 148 (1991) 271-377.

  10. REDUCTIVE ACTIVATION OF DIOXYGEN FOR DEGRADATION OF METHYL TERT-BUTYL ETHER BY BIFUNCTION

    EPA Science Inventory

    Bifunctional aluminum is prepared by sulfating aluminum metal with sulfuric acid. The use of bifunctional aluminum to degrade methyl tert-butyl ether (MTBE) in the presence of dioxygen has been examined using batch systems. Primary degradation products were tert-butyl alcohol, ...

  11. 40 CFR 721.6920 - Butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Butyl acrylate, polymer with... acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted silane. (a... butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

  12. 40 CFR 721.6920 - Butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Butyl acrylate, polymer with... acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted silane. (a... butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

  13. Primary quantum yields of ketyl radicals in photoreduction by amines. Abstraction of H from N

    SciTech Connect

    Inbar, S.; Linschitz, H.; Cohen, S.G.

    1980-02-13

    Results of laser flash photolysis studies of the primary reaction of benzophenone triplet with aliphatic amines in benzene solution are reported. Quantum yield of formation of benzophenone ketyl radical was 0.9 - 1.0. Quantum yields for reduction of ketone also were determined for various amines, and the effects of tert-butyl alcohol on radical formation was investigated. Data indicated that H is not abstracted from -CH/sub 3/ but is abstracted efficiently from -NH/sub 2/. The very high quantum yields observed with tertiary and secondary amines were thought to imply exciplex formation, but lower quantum yields with primary amines were conditionally attributed to higher ionization potentials. (BLM)

  14. Effect of various concentrations of butylated hydroxyanisole and butylated hydroxytoluene on freezing capacity of Turkman stallion sperm.

    PubMed

    Seifi-Jamadi, Afshin; Kohram, Hamid; Zareh-Shahne, Ahmad; Dehghanizadeh, Parvaneh; Ahmad, Ejaz

    2016-07-01

    The present study aimed to determine the effect of different concentrations of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) on post-thaw stallion sperm quality. The ejaculates collected from four healthy mature Turkmen stallions were pooled and divided into eight aliquots. The samples were diluted with extenders containing different concentrations (0.5, 1 or 2mM/mL) of BHA or BHT. The positive control (PC) samples were diluted with extender containing 0.5% ethanol (v/v) whereas; the negative control (NC) samples were diluted with basic extender only. Semen samples were frozen according to a standard protocol. After thawing of samples, sperm motility, viability, membrane integrity, total abnormality and lipid peroxidation were assessed. The greatest (P<0.05) values for total sperm motility, viability and plasma membrane functionality and least values for malonedialdehyde (MDA) concentration were observed in samples supplemented either with 1mM BHT or 2mM BHA. However, the progressive motility was greater (P<0.05) only in samples treated with 2mM BHA. In conclusion, the use of 1mM BHT or 2mM BHA in extender improves the freezing capacity of stallion sperm by reducing oxidative stress during freeze-thaw process. PMID:27112036

  15. Levels of synthetic antioxidants (ethoxyquin, butylated hydroxytoluene and butylated hydroxyanisole) in fish feed and commercially farmed fish.

    PubMed

    Lundebye, A-K; Hove, H; Måge, A; Bohne, V J B; Hamre, K

    2010-12-01

    Several synthetic antioxidants are authorized for use as feed additives in the European Union. Ethoxyquin (EQ) and butylated hydroxytoluene (BHT) are generally added to fish meal and fish oil, respectively, to limit lipid oxidation. The study was conducted to examine the concentrations of EQ, BHT and butylated hydroxyanisole (BHA) in several commercially important species of farmed fish, namely Atlantic salmon, halibut and cod and rainbow trout, as well as concentrations in fish feed. The highest levels of BHT, EQ and BHA were found in farmed Atlantic salmon fillets, and were 7.60, 0.17 and 0.07 mg kg(-1), respectively. The lowest concentrations of the synthetic antioxidants found were in cod. The concentration of the oxidation product ethoxyquin dimer (EQDM) was more than ten-fold higher than the concentration of parent EQ in Atlantic salmon halibut and rainbow trout, whereas this dimer was not detected in cod fillets. The theoretical consumer exposure to the synthetic antioxidants EQ, BHA and BHT from the consumption of farmed fish was calculated. The contribution of EQ from a single portion (300 g) of skinned fillets of the different species of farmed fish would contribute at most 15% of the acceptable daily intake (ADI) for a 60 kg adult. The consumption of farmed fish would not contribute measurably to the intake of BHA; however, a 300 g portion of farmed Atlantic salmon would contribute up to 75% of the ADI for BHT. PMID:20931417

  16. Peroxy radical partitioning during the AMMA radical intercomparison exercise

    NASA Astrophysics Data System (ADS)

    Andrés-Hernández, M. D.; Stone, D.; Brookes, D. M.; Commane, R.; Reeves, C. E.; Huntrieser, H.; Heard, D. E.; Monks, P. S.; Burrows, J. P.; Schlager, H.; Kartal, D.; Evans, M. J.; Floquet, C. F. A.; Ingham, T.; Methven, J.; Parker, A. E.

    2010-11-01

    Peroxy radicals were measured onboard two scientific aircrafts during the AMMA (African Monsoon Multidisciplinary Analysis) campaign in summer 2006. This paper reports results from the flight on 16 August 2006 during which measurements of HO2 by laser induced fluorescence spectroscopy at low pressure (LIF-FAGE) and total peroxy radicals (RO2* = HO2+ΣRO2, R = organic chain) by two similar instruments based on the peroxy radical chemical amplification (PeRCA) technique were subject of a blind intercomparison. The German DLR-Falcon and the British FAAM-BAe-146 flew wing tip to wing tip for about 30 min making concurrent measurements on 2 horizontal level runs at 697 and 485 hPa over the same geographical area in Burkina Faso. A full set of supporting measurements comprising photolysis frequencies, and relevant trace gases like CO, NO, NO2, NOy, O3 and a wider range of VOCs were collected simultaneously. Results are discussed on the basis of the characteristics and limitations of the different instruments used. Generally, no data bias are identified and the RO2* data available agree quite reasonably within the instrumental errors. The [RO2*]/[HO2] ratios, which vary between 1:1 and 3:1, as well as the peroxy radical variability, concur with variations in photolysis rates and in other potential radical precursors. Model results provide additional information about dominant radical formation and loss processes.

  17. Peroxy radical partitioning during the AMMA radical intercomparison exercise

    NASA Astrophysics Data System (ADS)

    Andrés-Hernández, M. D.; Stone, D.; Brookes, D. M.; Commane, R.; Reeves, C. E.; Huntrieser, H.; Heard, D. E.; Monks, P. S.; Burrows, J. P.; Schlager, H.; Kartal, D.; Evans, M. J.; Floquet, C. F. A.; Ingham, T.; Methven, J.; Parker, A. E.

    2010-04-01

    Peroxy radicals were measured onboard two scientific aircrafts during the AMMA (African Monsoon Multidisciplinary Analysis) campaign in summer 2006. This paper reports results from the flight on 16 August 2006 during which measurements of HO2 by laser induced fluorescence spectroscopy at low pressure (LIF-FAGE) and total peroxy radicals (RO2*=HO2+ΣRO2, R= organic chain) by two similar instruments based on the peroxy radical chemical amplification (PerCA) technique were subject of a blind intercomparison. The German DLR-Falcon and the British FAAM-BAe-146 flew wing tip to wing tip for about 30 min making concurrent measurements on 2 horizontal level runs at 697 and 485 hPa over the same geographical area in Burkina Faso. A full set of supporting measurements comprising photolysis frequencies, and relevant trace gases like CO, NO, NO2, NOy, O3 and a wider range of VOCs were collected simultaneously. Results are discussed on the basis of the characteristics and limitations of the different instruments used. Generally, no data bias are identified and the RO2* data available agree quite reasonably within the instrumental errors. The [RO2*]/[HO2] ratios, which vary between 1:1 and 3:1, as well as the peroxy radical variability, concur with variations in photolysis rates and in other potential radical precursors. Model results provide additional information about dominant radical formation and loss processes.

  18. A silver bullet: elemental silver as an efficient reducing agent for atom transfer radical polymerization of acrylates.

    PubMed

    Williams, Valerie A; Ribelli, Thomas G; Chmielarz, Pawel; Park, Sangwoo; Matyjaszewski, Krzysztof

    2015-02-01

    Elemental silver was used as a reducing agent in the atom transfer radical polymerization (ATRP) of acrylates. Silver wire, in conjunction with a CuBr(2)/TPMA catalyst, enabled the controlled, rapid preparation of polyacrylates with dispersity values down to Đ = 1.03. The silver wire in these reactions was reused several times in sequential reactions without a decline in performance, and the amount of copper catalyst used was reduced to 10 ppm without a large decrease in control. A poly(n-butyl acrylate)-block-poly(tert-butyl acrylate) diblock copolymer was synthesized with a molecular weight of 91 400 and Đ = 1.04, demonstrating good retention of chain-end functionality and a high degree of livingness in this ATRP system. PMID:25599253

  19. School Finance-Radical Departure.

    ERIC Educational Resources Information Center

    Kimple, James

    1983-01-01

    It is proposed that New Jersey assume approximately 70 percent of the cost of its public schools. Several other proposals are presented, all a radical departure from current school funding practices. (BW)

  20. Free radical inactivation of pepsin

    NASA Astrophysics Data System (ADS)

    Josimović, Lj; Ruvarac, I.; Janković, I.; Jovanović, S. V.

    1994-06-01

    Alkylperoxy radicals containing one, two or three chlorine atoms, CO -2, O 2 - were reacted with pepsin in aqueous solutions. It was found that only Cl 3COO and CO -2 inactive pepsin, attacking preferentially the disulfide bridge. Transient spectra obtained upon completion of the Cl 3COO + pepsin reaction at pH 5 indicate that 20% of initially produced Cl 3COO radicals oxidizes tryptophan residues, and 40% disulfide bridges. The inactivation induced by the Cl 3COO radical increases at lower pH, and the maximal inactivation, Gin = 5.8, was observed at pH 1.5. The inactivation of pepsin by CO -2 radicals depends on the absorbed dose. The maximal inactivation, Gin = 4.5, was determined in the dose range from 38 to 53 Gy.

  1. Redox Properties of Free Radicals.

    ERIC Educational Resources Information Center

    Neta, P.

    1981-01-01

    Describes pulse radiolysis as a useful means in studing one-electron redox potentials. This method allows the production of radicals and the determination of their concentration and rates of reaction. (CS)

  2. Interactions between water and 1-butyl-1-methylpyrrolidinium ionic liquids

    NASA Astrophysics Data System (ADS)

    Fadeeva, Tatiana A.; Husson, Pascale; DeVine, Jessalyn A.; Costa Gomes, Margarida F.; Greenbaum, Steven G.; Castner, Edward W.

    2015-08-01

    We report experimental results on the diffusivity of water in two ionic liquids obtained using the pulsed-gradient spin-echo NMR method. Both ionic liquids have the same cation, 1-butyl-1-methylpyrrolidinium, but different trifluoromethyl-containing anions. One has a strongly hydrophobic anion, bis(trifluoromethylsulfonyl)amide, while the second has a hydrophilic anion, trifluoromethylsulfonate. Transport of water in these ionic liquids is much faster than would be predicted from hydrodynamic laws, indicating that the neutral water molecules experience a very different friction than the anions and cations at the molecular level. Temperature-dependent viscosities, conductivities, and densities are reported as a function of water concentration to further analyze the properties of the ionic liquid-water mixtures. These results on the properties of water in ionic liquids should be of interest to researchers in diverse areas ranging from separations, solubilizing biomass and energy technologies.

  3. Endocrine disrupting effects of butylated hydroxyanisole (BHA - E320)

    PubMed Central

    POP, ANCA; KISS, BELA; LOGHIN, FELICIA

    2013-01-01

    Butylated hydroxyanisole (BHA) is extensively used as antioxidant in foods, food packaging, cosmetics and pharmaceuticals. In the past years, it raised concerns regarding its possible endocrine disrupting effect. The existing in vitro studies indicate that BHA presents a weak estrogenic effect and also anti-androgenic properties while an in vivo study found it to have antiestrogenic properties. There is no sufficient data available at the moment to draw a conclusion regarding the safety of BHA when referring to its endocrine disrupting effect. Since a fraction of the population might be exposed to doses superior to the acceptable daily intake (ADI), it is important to gather more in vitro and in vivo data concerning the potential effects that BHA might have alone, but also in mixtures with natural hormones or other endocrine disrupting compounds. PMID:26527908

  4. Interactions between water and 1-butyl-1-methylpyrrolidinium ionic liquids

    SciTech Connect

    Fadeeva, Tatiana A.; DeVine, Jessalyn A.; Castner, Edward W.; Husson, Pascale; Costa Gomes, Margarida F.; Greenbaum, Steven G.

    2015-08-14

    We report experimental results on the diffusivity of water in two ionic liquids obtained using the pulsed-gradient spin-echo NMR method. Both ionic liquids have the same cation, 1-butyl-1-methylpyrrolidinium, but different trifluoromethyl-containing anions. One has a strongly hydrophobic anion, bis(trifluoromethylsulfonyl)amide, while the second has a hydrophilic anion, trifluoromethylsulfonate. Transport of water in these ionic liquids is much faster than would be predicted from hydrodynamic laws, indicating that the neutral water molecules experience a very different friction than the anions and cations at the molecular level. Temperature-dependent viscosities, conductivities, and densities are reported as a function of water concentration to further analyze the properties of the ionic liquid-water mixtures. These results on the properties of water in ionic liquids should be of interest to researchers in diverse areas ranging from separations, solubilizing biomass and energy technologies.

  5. Interactions between water and 1-butyl-1-methylpyrrolidinium ionic liquids.

    PubMed

    Fadeeva, Tatiana A; Husson, Pascale; DeVine, Jessalyn A; Costa Gomes, Margarida F; Greenbaum, Steven G; Castner, Edward W

    2015-08-14

    We report experimental results on the diffusivity of water in two ionic liquids obtained using the pulsed-gradient spin-echo NMR method. Both ionic liquids have the same cation, 1-butyl-1-methylpyrrolidinium, but different trifluoromethyl-containing anions. One has a strongly hydrophobic anion, bis(trifluoromethylsulfonyl)amide, while the second has a hydrophilic anion, trifluoromethylsulfonate. Transport of water in these ionic liquids is much faster than would be predicted from hydrodynamic laws, indicating that the neutral water molecules experience a very different friction than the anions and cations at the molecular level. Temperature-dependent viscosities, conductivities, and densities are reported as a function of water concentration to further analyze the properties of the ionic liquid-water mixtures. These results on the properties of water in ionic liquids should be of interest to researchers in diverse areas ranging from separations, solubilizing biomass and energy technologies. PMID:26277141

  6. Hydrogen Atom Reactivity toward Aqueous tert-Butyl Alcohol

    SciTech Connect

    Lymar S. V.; Schwarz, H.A.

    2012-02-09

    Through a combination of pulse radiolysis, purification, and analysis techniques, the rate constant for the H + (CH{sub 3}){sub 3}COH {yields} H{sub 2} + {sm_bullet}CH{sub 2}C(CH{sub 3}){sub 2}OH reaction in aqueous solution is definitively determined to be (1.0 {+-} 0.15) x 10{sup 5} M{sup -1} s{sup -1}, which is about half of the tabulated number and 10 times lower than the more recently suggested revision. Our value fits on the Polanyi-type, rate-enthalpy linear correlation ln(k/n) = (0.80 {+-} 0.05){Delta}H + (3.2 {+-} 0.8) that is found for the analogous reactions of other aqueous aliphatic alcohols with n equivalent abstractable H atoms. The existence of such a correlation and its large slope are interpreted as an indication of the mechanistic similarity of the H atom abstraction from {alpha}- and {beta}-carbon atoms in alcohols occurring through the late, product-like transition state. tert-Butyl alcohol is commonly contaminated by much more reactive secondary and primary alcohols (2-propanol, 2-butanol, ethanol, and methanol), whose content can be sufficient for nearly quantitative scavenging of the H atoms, skewing the H atom reactivity pattern, and explaining the disparity of the literature data on the H + (CH{sub 3}){sub 3}COH rate constant. The ubiquitous use of tert-butyl alcohol in pulse radiolysis for investigating H atom reactivity and the results of this work suggest that many other previously reported rate constants for the H atom, particularly the smaller ones, may be in jeopardy.

  7. [Alcohol and free oxygen radicals].

    PubMed

    Mira, M L; Manso, C F

    1993-05-01

    Oxygen free radicals may be generated during ethanol metabolization by cytochrome P450, or due to the formation of xanthine oxidase by ethanol effect on xanthine dehydrogenase. After transformation into acetaldehyde, the metabolism of this compound by xanthine oxidase or by aldehyde oxidase also generates oxygen radicals. We present the hypothesis of a vicious cycle during ethanol metabolization by aldehyde oxidase, which would amplify the process and be responsible for an increased degree of lipid peroxidation. PMID:8393265

  8. A Combined Experimental and Theoretical Approach to the Photogeneration of 5,6-Dihydropyrimidin-5-yl Radicals in Nonaqueous Media.

    PubMed

    Aparici-Espert, Isabel; Francés-Monerris, Antonio; Rodríguez-Muñiz, Gemma M; Roca-Sanjuán, Daniel; Lhiaubet-Vallet, Virginie; Miranda, Miguel A

    2016-05-20

    The chemical fate of radical intermediates is relevant to understand the biological effects of radiation and to explain formation of DNA lesions. A direct approach to selectively generate the putative reactive intermediates is based on the irradiation of photolabile precursors. But, to date, radical formation and reactivity have only been studied in aqueous media, which do not completely mimic the microenvironment provided by the DNA structure and its complexes with proteins. Thus, it is also important to evaluate the photogeneration of nucleoside-based radicals in nonaqueous media. The attention here is focused on the independent generation of 5,6-dihydropyrimidin-5-yl radicals in organic solvent through the synthesis of new lipophilic tert-butyl ketone precursors. Formation of 5,6-dihydro-2'-deoxyuridin-5-yl and 5,6-dihydrothymidin-5-yl radicals has first been confirmed by using a new nitroxide-derived profluorescent radical trap. Further evidence has been obtained by nanosecond laser flash photolysis through detection of long-lived transients. Finally, the experimental data are corroborated by multiconfigurational ab initio CASPT2//CASSCF methodology. PMID:27088245

  9. Genotoxicity of di-butyl-phthalate and di-iso-butyl-phthalate in human lymphocytes and mucosal cells.

    PubMed

    Kleinsasser, N H; Wallner, B C; Kastenbauer, E R; Weissacher, H; Harréus, U A

    2001-01-01

    The genotoxicity of phthalates, widely used plasticizers, has been shown previously for di-butyl-phthalate (DBP) and di-iso-butyl-phthalate (DBP) in human mucosal cells of the upper aerodigestive tract in a previous study using the Comet assay. Furthermore, higher genotoxic sensitivities of patients with squamous cell carcinomas of either the larynx or the oropharynx compared to non-tumor patients were described. Other authors have demonstrated DNA damage by a different phthalate in human lymphocytes. It was the aim of the present study to determine whether there is a correlation between the genotoxic sensitivities to DBP and its isomer DiBP in either mucosal cells or lymphocytes. The single-cell microgel electrophoresis assay (Comet assay) was applied to detect DNA strand breaks in human epithelial cells of the upper aerodigestive tract (n=132 specimens). Human mucosa was harvested from the oropharynx in non-tumor patients and patients with squamous cell carcinomas of the oropharynx. Laryngeal mucosa of patients with laryngeal squamous cell carcinomas was harvested as well. Peripheral lymphocytes (n=49 specimens) were separated from peripheral blood. Xenobiotics investigated were DBP, DiBP, and N'methyl-N'-nitro-N-nitrosoguanidine (MNNG) as positive control, respectively. For statistical analysis, the SPSS correlation analysis according to Pearson and the Wilcoxon test were performed. Genotoxicity was found for DBP and DiBP in epithelial cells and lymphocytes (P<0.001). MNNG caused severe DNA damage. In analyzing DBP and DiBP results, genotoxic impacts in mucosal cells showed an intermediate correlation (r=0.570). Correlation in lymphocytes was the same (r=0.570). Phthalates have been investigated as a potential health hazard for a variety of reasons, including possible xenoestrogenic impact, peroxisome proliferation, and membrane destabilization. The present investigation suggests a correlated DNA-damaging impact of DBP and DiBP in human mucosal cells and in

  10. Hepatoprotective Activity of Water Extracts from Chaga Medicinal Mushroom, Inonotus obliquus (Higher Basidiomycetes) Against Tert-Butyl Hydroperoxide-Induced Oxidative Liver Injury in Primary Cultured Rat Hepatocytes.

    PubMed

    Hong, Ki Bae; Noh, Dong Ouk; Park, Yooheon; Suh, Hyung Joo

    2015-01-01

    We examined the hepatoprotective activity of Inonotus obliquus water extract (IO-W) against tert-butyl hydroperoxide (t-BHP)-induced oxidative liver injury in the primary cultured rat hepatocyte. The 50% radical scavenging concentrations (SC50s) of IO-W for radical-scavenging activity against 2,2'-azino-bis-(3-ethylbenzothi- azoline-6-sulfonic acid) (ABTS) and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) were 5.19 mg/mL and 0.39 mg/mL, respectively. IO-W pretreatment to the primary cultured hepatocytes significantly (p<0.05) protected the cells from t-BHP-induced cytotoxic injury even at a low concentration of IO-W (10 µg/mL). The cellular leakage of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH), as well as malondialdehyde (MDA) formation caused by t-BHP were significantly (p<0.05) suppressed by IO-W pretreatment (>100 µg/ mL). In conclusion, this study demonstrates that IO-W exhibited hepatoprotective activity against t-BHP-induced oxidative liver injury in the primary cultured hepatocyte probably via its abilities of quenching free radicals, inhibiting the leakage of ALT, AST, and LDH, and decreasing MDA formation. PMID:26853962

  11. Rational Design and Synthesis of New, High Efficiency, Multipotent Schiff Base-1,2,4-triazole Antioxidants Bearing Butylated Hydroxytoluene Moieties.

    PubMed

    Yehye, Wageeh A; Abdul Rahman, Noorsaadah; Saad, Omar; Ariffin, Azhar; Abd Hamid, Sharifah Bee; Alhadi, Abeer A; Kadir, Farkaad A; Yaeghoobi, Marzieh; Matlob, Abdulsalam A

    2016-01-01

    A new series of multipotent antioxidants (MPAOs), namely Schiff base-1,2,4-triazoles attached to the oxygen-derived free radical scavenging moiety butylated hydroxytoluene (BHT) were designed and subsequently synthesized. The structure-activity relationship (SAR) of the designed antioxidants was established alongside the prediction of activity spectra for substances (PASS). The antioxidant activities of the synthesized compounds 4-10 were tested by the DPPH bioassay. The synthesized compounds 4-10 inhibited stable DPPH free radicals at a level that is 10(-4) M more than the well-known standard antioxidant BHT. Compounds 8-10 with para-substituents were less active than compounds 4 and 5 with trimethoxy substituents compared to those with a second BHT moiety (compounds 6 and 7). With an IC50 of 46.13 ± 0.31 µM, compound 6 exhibited the most promising in vitro inhibition at 89%. Therefore, novel MPAOs containing active triazole rings, thioethers, Schiff bases, and BHT moieties are suggested as potential antioxidants for inhibiting oxidative stress processes and scavenging free radicals, hence, this combination of functions is anticipated to play a vital role in repairing cellular damage, preventing various human diseases and in medical therapeutic applications. PMID:27367658

  12. Voltammetric Determination of Dinonyl Diphenylamine and Butylated Hydroxytoluene in Mineral and Synthetic Oil

    PubMed Central

    Xiang, Yaling; Qian, Xuzheng; Hua, Meng; Cheng, Bingxue; Chen, Wu; Li, Jian

    2016-01-01

    ABSTRACT A method is reported for the determination of diphenylamine and butylated hydroxytoluene in mineral and synthetic oil. The procedure used differential pulse voltammetry with a glassy carbon electrode. This method was then used for determining these antioxidants in supporting electrolyte consisting of dilute sulfuric acid and sodium dodecyl sulfonate in ethanol. Anodic peaks were obtained for both analytes. Oxidation peaks at 250 mV were observed from a mixture of butylated hydroxytoluene and dinonyl diphenylamine, allowing their simultaneous determination. This approach was successfully used for the determination of dinonyl diphenylamine and butylated hydroxytoluene in fortified mineral and synthetic oils with good accuracy and precision. PMID:27365537

  13. Crystalline bipyridinium radical complexes and uses thereof

    DOEpatents

    Fahrenbach, Albert C.; Barnes, Jonathan C.; Li, Hao; Stoddart, J. Fraser; Basuray, Ashish Neil; Sampath, Srinivasan

    2015-09-01

    Described herein are methods of generating 4,4'-bipyridinium radical cations (BIPY.sup..cndot.+), and methods for utilizing the radical-radical interactions between two or more BIPY.sup..cndot.+ radical cations that ensue for the creation of novel materials for applications in nanotechnology. Synthetic methodologies, crystallographic engineering techniques, methods of physical characterization, and end uses are described.

  14. Picosecond Spectroscopy of Reactive Intermediates: Generation and Dynamics of Arylmethyl Ions and Radicals in Solution.

    NASA Astrophysics Data System (ADS)

    Schmidt, Jeffrey Allan

    A detailed experimental description is presented of a practical and relatively inexpensive approach for two simultaneous and independent types of picosecond spectroscopic measurements. Two data collection subsystems, (1) a picosecond pump-probe transient absorption/emission spectrometer and (2) a streak camera system for time-dependent measurements of absorption and emission, were developed as independent subsystems within an integrated system based on a single mode-locked Nd:YAG laser which concurrently supplies each subsystem with picosecond pulses. Considerations concerning electrical and optical interfacing between the two subsystems are discussed. With these two subsystems, picosecond-pulsed photolyses of diphenylmethyl chloride, diphenylmethyl bromide, triphenylmethyl chloride, triphenylmethyl bromide, and triphenylacetyl chloride in acetonitrile, methylene chloride, and cyclohexane were studied. The dependence of the yields of radicals and ions are discussed with respect to the nature of the starting compound and the solvent. Ion-pair dynamics were monitored with subsystems 1 and 2. Microscopic rate constants for the collapse of the contact ion pair (CIP), separation of the CIP, and reformation of the CIP from the separated ions were calculated. The photophysics and photochemistry of the triphenylmethyl radical generated from triphenylmethyl chloride, and triphenylacetyl chloride, and tert-butyl triphenylperacetate in solution were studied by means of a unique three-pulse picosecond transient absorption technique. The emission lifetime of the excited triphenylmethyl radical was measured as a function of solvent polarity with subsystem 2. These data were collectively used to gain an understanding of the electronically excited triphenylmethyl radical.

  15. Catalase Expression Is Modulated by Vancomycin and Ciprofloxacin and Influences the Formation of Free Radicals in Staphylococcus aureus Cultures

    PubMed Central

    Wang, Ying; Hougaard, Anni B.; Paulander, Wilhelm; Skibsted, Leif H.

    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 formation in the human pathogen Staphylococcus aureus treated with a bactericidal antibiotic, vancomycin or ciprofloxacin. While we were unable to detect ESR signals in bacterial cells, hydroxyl radicals were observed in the supernatant of bacterial cell cultures. Surprisingly, the strongest signal was detected in broth medium without bacterial cells present and it was mitigated by iron chelation or by addition of catalase, which catalyzes the decomposition of hydrogen peroxide to water and oxygen. This suggests that the signal originates from hydroxyl radicals formed by the Fenton reaction, in which iron is oxidized by hydrogen peroxide. Previously, hydroxyl radicals have been proposed to be generated within bacterial cells in response to bactericidal antibiotics. We found that when S. aureus was exposed to vancomycin or ciprofloxacin, hydroxyl radical formation in the broth was indeed increased compared to the level seen with untreated bacterial cells. However, S. aureus cells express catalase, and the antibiotic-mediated increase in hydroxyl radical formation was correlated with reduced katA expression and catalase activity in the presence of either antibiotic. Therefore, our results show 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. PMID:26150471

  16. Design, synthesis and characterization of neutral radical organic conductors: The spiro-bis (1,9-disubstituted phenalenyl) boron system

    NASA Astrophysics Data System (ADS)

    Chi, Xiaoliu

    2001-07-01

    Novel electronic devices (LED, FET, etc.) and room-temperature superconductivity are the most challenging fields in material science. Progress in these fields relies on the design and synthesis of new materials that have novel electronic properties in the solid state. Organic conductors and superconductors have focused on charge-transfer salts for more than 30 years. Although progress has been made, the transition temperatures of the majority of organic superconductors are far less than those of the ceramic-based superconductors. In 1975 Haddon predicted in a Nature article that neutral radicals, especially the phenalenyl system (PLY), could be used to make organic conductors and superconductors. Spiro-biphenalenyl boron radicals were proposed to be promising candidates in that they potentially form high-dimensional solids with a quarter-filled energy bands, which are thought to be important in stabilizing the metallic state. The synthesis of these radical crystals includes the preparation of various ligands and then their boron complexes, the purification of the precursors, the search for suitable reducing reagents and the crystallization of the radicals. Hexyl radical (27) is monomeric in the solid state, and shows Curie behavior throughout the temperature ranges 10--400 K. At room-temperature its conductivity sigma reaches 0.05 S/cm, the highest yet for a neutral organic molecular solid. Ethyl radical (23) has parallel PLY planes in the solid state, which form diamagnetic pi dimers below 150K, while butyl radical (25) forms a diamagnetic dimer at 340K. Surprisingly the conductivity increases sharply by two orders of magnitude at the transition to the dimerized state in both compounds. Interestingly, propyl radical (24) has a conductivity four orders of magnitude smaller than those of all other compounds mentioned. The location of the electrons in the radicals was studied. Several conductivity models were proposed based on the experimental results. By a careful

  17. Catalase Expression Is Modulated by Vancomycin and Ciprofloxacin and Influences the Formation of Free Radicals in Staphylococcus aureus Cultures.

    PubMed

    Wang, Ying; Hougaard, Anni B; Paulander, Wilhelm; Skibsted, Leif H; Ingmer, Hanne; Andersen, Mogens L

    2015-09-01

    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 formation in the human pathogen Staphylococcus aureus treated with a bactericidal antibiotic, vancomycin or ciprofloxacin. While we were unable to detect ESR signals in bacterial cells, hydroxyl radicals were observed in the supernatant of bacterial cell cultures. Surprisingly, the strongest signal was detected in broth medium without bacterial cells present and it was mitigated by iron chelation or by addition of catalase, which catalyzes the decomposition of hydrogen peroxide to water and oxygen. This suggests that the signal originates from hydroxyl radicals formed by the Fenton reaction, in which iron is oxidized by hydrogen peroxide. Previously, hydroxyl radicals have been proposed to be generated within bacterial cells in response to bactericidal antibiotics. We found that when S. aureus was exposed to vancomycin or ciprofloxacin, hydroxyl radical formation in the broth was indeed increased compared to the level seen with untreated bacterial cells. However, S. aureus cells express catalase, and the antibiotic-mediated increase in hydroxyl radical formation was correlated with reduced katA expression and catalase activity in the presence of either antibiotic. Therefore, our results show 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. PMID:26150471

  18. An on-line normal-phase high performance liquid chromatography method for the rapid detection of radical scavengers in non-polar food matrixes.

    PubMed

    Zhang, Qiang; van der Klift, Elbert J C; Janssen, Hans-Gerd; van Beek, Teris A

    2009-10-23

    An on-line method for the rapid pinpointing of radical scavengers in non-polar mixtures like vegetable oils was developed. To avoid problems with dissolving the sample, normal-phase chromatography on bare silica gel was used with mixtures of hexane and methyl tert-butyl ether as the eluent. The high performance liquid chromatography-separated analytes are mixed post-column with a solution of stable free radicals in hexane. Reduced levels of the radical as a result of a reaction with a radical scavenger are detected as negative peaks by an absorbance detector. After investigating a number of different reagents, solvents, concentrations and solution flow rates an optimized instrumental set-up incorporating a superloop for pulse-free delivery of the reagent solution is presented. Both 2,2'-diphenyl-1-picrylhydrazyl (DPPH) and 2,6-di-tert-butyl-alpha-(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadien-1-ylidene)-p-tolyloxy (galvinoxyl) were used as stable free radicals. The method is suitable for both isocratic and gradient HPLC operation. The method has a simple experimental protocol, uses standard instruments and inexpensive and stable reagents, and accepts any hexane-soluble sample. It can also be used for semi-quantitative analysis. The method was applied to several pure, non-polar natural antioxidants, vegetable oils and lipid-soluble rosemary extract. The limits of detection varied from 0.2 to 176 microg/ml, depending on the compound tested. PMID:19726044

  19. Standard Electrode Potentials Involving Radicals in Aqueous Solution: Inorganic Radicals

    SciTech Connect

    Armstrong, David A.; Huie, Robert E.; Koppenol, Willem H.; Lymar, Sergei V.; Merenyi, Gabor; Neta, Pedatsur; Ruscic, Branko; Stanbury, David M.; Steenken, Steen; Wardman, Peter

    2015-12-01

    Recommendations are made for standard potentials involving select inorganic radicals in aqueous solution at 25 °C. These recommendations are based on a critical and thorough literature review and also by performing derivations from various literature reports. The recommended data are summarized in tables of standard potentials, Gibbs energies of formation, radical pKa’s, and hemicolligation equilibrium constants. In all cases, current best estimates of the uncertainties are provided. An extensive set of Data Sheets is appended that provide original literature references, summarize the experimental results, and describe the decisions and procedures leading to each of the recommendations

  20. Mechanically Stabilized Tetrathiafulvalene Radical Dimers

    SciTech Connect

    Coskun, Ali; Spruell, Jason M.; Barin, Gokhan; Fahrenbach, Albert C.; Forgan, Ross S.; Colvin, Michael T.; Carmieli, Raanan; Benitez, Diego; Tkatchouk, Ekaterina; Friedman, Douglas C.; Sarjeant, Amy A.; Wasielewski, Michael R.; Goddard, William A.; Stoddart, J. Fraser

    2011-01-01

    Two donor-acceptor [3]catenanes—composed of a tetracationic molecular square, cyclobis(paraquat-4,4'-biphenylene), as the π-electron deficient ring and either two tetrathiafulvalene (TTF) and 1,5-dioxynaphthalene (DNP) containing macrocycles or two TTF-butadiyne-containing macrocycles as the π-electron rich components—have been investigated in order to study their ability to form TTF radical dimers. It has been proven that the mechanically interlocked nature of the [3]catenanes facilitates the formation of the TTF radical dimers under redox control, allowing an investigation to be performed on these intermolecular interactions in a so-called “molecular flask” under ambient conditions in considerable detail. In addition, it has also been shown that the stability of the TTF radical-cation dimers can be tuned by varying the secondary binding motifs in the [3]catenanes. By replacing the DNP station with a butadiyne group, the distribution of the TTF radical-cation dimer can be changed from 60% to 100%. These findings have been established by several techniques including cyclic voltammetry, spectroelectrochemistry and UV-vis-NIR and EPR spectroscopies, as well as with X-ray diffraction analysis which has provided a range of solid-state crystal structures. The experimental data are also supported by high-level DFT calculations. The results contribute significantly to our fundamental understanding of the interactions within the TTF radical dimers.

  1. Alkoxyl radical-scavenging activity of edaravone in patients with traumatic brain injury.

    PubMed

    Dohi, Kenji; Satoh, Kazue; Mihara, Yuko; Nakamura, Shunsuke; Miyake, Yasuhumi; Ohtaki, Hirokazu; Nakamachi, Tomoya; Yoshikawa, Toshikazu; Shioda, Seiji; Aruga, Tohru

    2006-11-01

    Lipid peroxidation is caused by reactive oxygen species (ROS) and is involved in traumatic brain injury (TBI). Consequently, a therapeutic strategy for TBI may be to control lipid peroxidation. The only drug approved to date for blocking lipid peroxidation is edaravone (MCI-186), a novel free-radical scavenger shown to exert neuroprotective effects in acute ischemic stroke. Although edaravone scavenges hydroxyl and nitric oxide radicals, its effect on alkoxyl radicals (OR-), which also contribute to lipid peroxidation, is unknown. To date, the study of free radicals in blood has been severely hampered by technical difficulties in their detection. We used an in vitro and ex vivo electron spin resonance (ESR) method employing 5,5-dimethyl-1-pyrroline-N-oxide as a spin trap to investigate whether edaravone can scavenge OR-. By mixing either methemoglobin or human blood with tert-butyl hydroperoxide, we found that this technique can detect OR- generated in vitro. We also found that generated OR- can be completely absorbed by administration of edaravone in vitro (400 microM). Analysis of jugular venous blood collected from 17 TBI patients immediately before and 20 minutes after the administration of edaravone (30 mg, i.v.) revealed higher OR- levels in the untreated patients blood than in normal control blood samples. However, treatment with edaravone suppressed these OR- levels by 24.6% (radical intensity = 71.1 +/- 5.2-53.6 +/- 5.2; p < 0.01). Thus, edaravone can scavenge OR- and significantly reduce levels of these radicals in TBI patients. The novel ex vivo ESR method described here provides a valuable clinical measure of oxidative stress. PMID:17115906

  2. Radical-Mediated Enzymatic Polymerizations

    PubMed Central

    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. Epistemological barriers to radical behaviorism

    PubMed Central

    O'Donohue, William T.; Callaghan, Glenn M.; Ruckstuhl, L. E.

    1998-01-01

    The historian and philosopher of science Gaston Bachelard proposed the concept of epistemological barriers to describe the intellectual challenges encountered by scientists in their work. In order to embrace novel ways of approaching a problem in science, scientists must overcome barriers or obstacles posed by their prior views. For example, Einsteinian physics presents scientists with claims that space is curved and that time and space are on the same continuum. We utilize Bachelard's concept of epistemological barriers to describe the differences between the intellectual journeys students pursuing advanced studies face when attempting to accept cognitive psychology or radical behaviorism. We contend that the folk psychological beliefs that students typically hold when entering these studies pose less challenge to cognitive psychology than to radical behaviorism. We also suggest that these barriers may also partly be involved in the problematic exegesis that has plagued radical behaviorism. In close, we offer some suggestions for dealing with these epistemological barriers. PMID:22478314

  4. Free radical decay in adamantane

    SciTech Connect

    Tegowski, A.T.; Pratt, D.W.

    1984-01-11

    Kinetic electron paramagnetic resonance (EPR) techniques have been used to characterize the decay behavior of the ''stable'' free radical 2-cyclohexanonyl in the plastic crystal phase f an adamantane matrix over the temperature range 257-313 K. Typical plots of the EPR signal intensity as a function of time are biexponential in nature, suggesting the existence of at least two channels for free radical decay. The activation parameters for both processes have been measured in both protonated and deuterated samples. A comparison of these results with those in other systems suggests that the host does, as expected, considerably reduce the pre-exponential factors for decay of the radical by bimolecular processes but has relatively little influence on the corresponding activation energies. 3 figures.

  5. Radical-Mediated Enzymatic Polymerizations.

    PubMed

    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

  6. DETERMINATION OF THIOCARBAMATES IN INDUSTRIAL AND MUNICIPAL WASTEWATER - BUTYLATE, CYCLOATE, EPTC, MOLINATE, PEBULATE, AND VERNOLATE

    EPA Science Inventory

    A method was developed for the determination of six thiocarbamate compounds (butylate, cycloate, EPTC, molinate, pebulate, and vernolate) in wastewaters. The method development program consisted of a literature review; determination of extraction efficiency for each compound from...

  7. Cerebral and splenic infarctions after injection of N-butyl-2-cyanoacrylate in esophageal variceal bleeding.

    PubMed

    Myung, Dae-Seong; Chung, Cho-Yun; Park, Hyung-Chul; Kim, Jong-Sun; Cho, Sung-Bum; Lee, Wan-Sik; Choi, Sung-Kyu; Joo, Young-Eun

    2013-09-14

    Variceal bleeding is the most serious complication of portal hypertension, and it accounts for approximately one fifth to one third of all deaths in liver cirrhosis patients. Currently, endoscopic treatment remains the predominant method for the prevention and treatment of variceal bleeding. Endoscopic treatments include band ligation and injection sclerotherapy. Injection sclerotherapy with N-butyl-2-cyanoacrylate has been successfully used to treat variceal bleeding. Although injection sclerotherapy with N-butyl-2-cyanoacrylate provides effective treatment for variceal bleeding, injection of N-butyl-2-cyanoacrylate is associated with a variety of complications, including systemic embolization. Herein, we report a case of cerebral and splenic infarctions after the injection of N-butyl-2-cyanoacrylate to treat esophageal variceal bleeding. PMID:24039373

  8. Cerebral and splenic infarctions after injection of N-butyl-2-cyanoacrylate in esophageal variceal bleeding

    PubMed Central

    Myung, Dae-Seong; Chung, Cho-Yun; Park, Hyung-Chul; Kim, Jong-Sun; Cho, Sung-Bum; Lee, Wan-Sik; Choi, Sung-Kyu; Joo, Young-Eun

    2013-01-01

    Variceal bleeding is the most serious complication of portal hypertension, and it accounts for approximately one fifth to one third of all deaths in liver cirrhosis patients. Currently, endoscopic treatment remains the predominant method for the prevention and treatment of variceal bleeding. Endoscopic treatments include band ligation and injection sclerotherapy. Injection sclerotherapy with N-butyl-2-cyanoacrylate has been successfully used to treat variceal bleeding. Although injection sclerotherapy with N-butyl-2-cyanoacrylate provides effective treatment for variceal bleeding, injection of N-butyl-2-cyanoacrylate is associated with a variety of complications, including systemic embolization. Herein, we report a case of cerebral and splenic infarctions after the injection of N-butyl-2-cyanoacrylate to treat esophageal variceal bleeding. PMID:24039373

  9. 40 CFR 721.6920 - Butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... substituted methyl styrene, methyl methacrylate, and substituted silane. 721.6920 Section 721.6920 Protection... acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted silane. (a... butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

  10. 40 CFR 721.6920 - Butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... substituted methyl styrene, methyl methacrylate, and substituted silane. 721.6920 Section 721.6920 Protection... acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted silane. (a... butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

  11. 40 CFR 721.6920 - Butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... substituted methyl styrene, methyl methacrylate, and substituted silane. 721.6920 Section 721.6920 Protection... acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted silane. (a... butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

  12. INFLUENCE OF METHYL TERT-BUTYL ETHER (MTBE) ON LAKE WATER ALGAE: JOURNAL ARTICLE

    EPA Science Inventory

    NRMRL-ADA-01209 Kampbell*, D.H., An, Y, and Williams, VR. Influence of Methyl tert-Butyl Ether (MTBE) on Lake Water Algae. Bulletin of Environmental Contamination and Toxicology 57 (4):675-681 (2001). ...

  13. The reclaiming of butyl rubber and in-situ compatibilization of thermoplastic elastomer by power ultrasound

    NASA Astrophysics Data System (ADS)

    Feng, Wenlai

    This is a study of the continuous ultrasound aided extrusion process for the in-situ compatibilization of isotactic polypropylene (iPP)/ethylene-propylene diene rubber (EPDM) thermoplastic elastomer (TPE) using a newly developed ultrasonic treatment reactor. The rheological, mechanical properties and morphology of the TPE with and without ultrasonic treatment were studied. In-situ compatibilization in the ultrasonically treated blends was observed as evident by their more stable morphology after annealing, improved mechanical properties and IR spectra. The obtained results indicated that ultrasonic treatment induced the thermo-mechanical degradations and led to the possibility of enhanced molecular transport and chemical reactions at the interfaces. Processing conditions were established for enhanced in situ compatibilization of the PP/EPDM TPE. The ultrasonic treatments of butyl rubber gum and ultrasonic devulcanization of butyl rubber, tire-curing bladder during extrusion using a grooved barrel ultrasonic reactor were carried out. The ultrasonic treatment of gum caused degradation of the polymer main chain leading to lower molecular weight, broader molecular weight distribution, less unsaturation and changes in physical properties. The devulcanization of butyl rubber was successfully accomplished only at severe conditions of ultrasonic treatment. The mechanical properties of vulcanizates prepared from devulcanized butyl rubber are comparable to that of the virgin vulcanizate. The molecular characterization of sol fraction of devulcanized butyl rubber showed the devulcanization and degradation of butyl rubber occurred simultaneously. 1H NMR transverse relaxation was also used to study butyl rubber gum before and after ultrasonic treatment, and ultrasonically devulcanized unfilled butyl rubber. The T2 relaxation decays were successfully described using a two-component model. The recyclability of tire-curing bladder was also investigated. Gel fraction, crosslink

  14. Fenton-like degradation of MTBE: Effects of iron counter anion and radical scavengers.

    PubMed

    Hwang, Sangchul; Huling, Scott G; Ko, Saebom

    2010-01-01

    Fenton-driven oxidation of methyl tert-butyl ether (MTBE) (0.11-0.16mM) in batch reactors containing ferric iron (5mM) and hydrogen peroxide (H(2)O(2)) (6mM) (pH=3) was performed to investigate MTBE transformation mechanisms. Independent variables included the forms of iron (Fe) (Fe(2)(SO(4))(3).9H(2)O and Fe(NO(3))(3).9H(2)O), H(2)O(2) (6, 60mM), chloroform (CF) (0.2-2.4mM), isopropyl alcohol (IPA) (25, 50mM), and sulfate (7.5mM). MTBE, tert-butyl alcohol and acetone transformation were significantly greater when oxidation was carried out with Fe(NO(3))(3).9H(2)O than with Fe(2)(SO(4))(3).9H(2)O. Sulfate interfered in the formation of the ferro-peroxy intermediate species, inhibited H(2)O(2) reaction, hydroxyl radical (()OH) formation, and MTBE transformation. Transformation was faster and more complete at a higher [H(2)O(2)] (60mM), but resulted in lower oxidation efficiency which was attributed to ()OH scavenging by H(2)O(2). CF scavenging of the superoxide radical (()O(2)(-)) in the ferric nitrate system resulted in lower rates of ()O(2)(-) reduction of Fe(III) to Fe(II), ()OH production, and consequently lower rates of MTBE transformation. IPA, an excellent scavenger of ()OH, completely inhibited MTBE transformation in the ferric nitrate system indicating oxidation was predominantly by ()OH. ()OH scavenging by HSO(4)(-), formation of the sulfate radical (()SO(4)(-)), and oxidation of MTBE by ()SO(4)(-) was estimated to be negligible. The form of Fe (i.e., counter anion) selected for use in Fenton treatment systems impacts oxidative mechanisms, treatment efficiency, and post-oxidation treatment of residuals which may require additional handling and cost. PMID:19959205

  15. Donor free radical explosive composition

    DOEpatents

    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.

  16. Occupational exposures to new dry cleaning solvents: High-flashpoint hydrocarbons and butylal.

    PubMed

    Ceballos, Diana M; Whittaker, Stephen G; Lee, Eun Gyung; Roberts, Jennifer; Streicher, Robert; Nourian, Fariba; Gong, Wei; Broadwater, Kendra

    2016-10-01

    The dry cleaning industry is moving away from using perchloroethylene. Occupational exposures to two alternative dry cleaning solvents, butylal and high-flashpoint hydrocarbons, have not been well characterized. We evaluated four dry cleaning shops that used these alternative solvents. The shops were staffed by Korean- and Cantonese-speaking owners, and Korean-, Cantonese-, and Spanish-speaking employees. Because most workers had limited English proficiency we used language services in our evaluations. In two shops we collected personal and area air samples for butylal. We also collected air samples for formaldehyde and butanol, potential hydrolysis products of butylal. Because there are no occupational exposure limits for butylal, we assessed employee health risks using control banding tools. In the remaining two shops we collected personal and area air samples for high-flashpoint hydrocarbon solvents. In all shops the highest personal airborne exposures occurred when workers loaded and unloaded the dry cleaning machines and pressed dry cleaned fabrics. The air concentrations of formaldehyde and butanol in the butylal shops were well below occupational exposure limits. Likewise, the air concentrations of high-flashpoint hydrocarbons were also well below occupational exposure limits. However, we saw potential skin exposures to these chemicals. We provided recommendations on appropriate work practices and the selection and use of personal protective equipment. These recommendations were consistent with those derived using control banding tools for butylal. However, there is insufficient toxicological and health information to determine the safety of butylal in occupational settings. Independent evaluation of the toxicological properties of these alternative dry cleaning solvents, especially butylal, is urgently needed. PMID:27105306

  17. Etude de l'effet du gonflement par les solvants sur les proprietes du caoutchouc butyle

    NASA Astrophysics Data System (ADS)

    Nohile, Cedrick

    Polymers and in particular elastomers are widely used for personal protective equipment against chemical and biological hazards. Among them, butyl rubber is one of the most effective elastomers against chemicals. However, if this rubber has a very good resistance to a wide range of them, it is sensitive to non polar solvents. These solvents will easily swell the material and may dramatically affect its properties. This situation may involve a large risk for. butyl rubber protective equipment users. It is thus essential to improve the understanding of the effect of solvents on the properties of butyl rubber. The research that was carried out had two objectives: to identify the parameters controlling the resistance of butyl rubber to solvents and to study the effect of swelling on the properties of butyl rubber. The results show that the resistance of butyl rubber to solvents appears to be controlled by three main parameters: the chemical class of the solvent, its saturation vapor pressure and its molar volume. In addition, swelling affects butyl rubber mechanical properties in a permanent way. The effects can be attributed to the extraction of plasticizers by the solvent and to the degradation of the physico-chemical structure of the polymer network. This chemical degradation was linked to a phenomenon of differential swelling which seems to be controlled by the solvent flow inside the material. These results question some general beliefs within the field of protection against chemical risks. They also open new perspectives for the development of predictive tools relative to the behavior of butyl rubber in the presence of solvents

  18. Permeability of noble gases through Kapton, butyl, nylon, and “Silver Shield”

    NASA Astrophysics Data System (ADS)

    Schowalter, Steven J.; Connolly, Colin B.; Doyle, John M.

    2010-04-01

    Noble gas permeabilities and diffusivities of Kapton, butyl, nylon, and "Silver Shield" are measured at temperatures between 22 and 115C. The breakthrough times and solubilities at 22C are also determined. The relationship of the room temperature permeabilities to the noble gas atomic radii is used to estimate radon permeability for each material studied. For the noble gases tested, Kapton and Silver Shield have the lowest permeabilities and diffusivities, followed by nylon and butyl, respectively.

  19. The impact of groundwater quality on the removal of methyl tertiary-butyl ether (MTBE) using advanced oxidation technology.

    PubMed

    Tawabini, B; Fayad, N; Morsy, M

    2009-01-01

    In this study, the removal of methyl tertiary-butyl ether (MTBE) from contaminated groundwater using advanced oxidation technology was investigated. The UV/H(2)O(2) treatment process was applied to remove MTBE from two Saudi groundwater sources that have different quality characteristics with regard to their contents of inorganic species such as chloride, bromide, sulfates and alkalinity. MTBE was spiked into water samples collected from the two sources to a concentration level of about 250 microg/L. A 500 mL bench-scale forced-liquid circulation photoreactor was used to conduct the experiments. Two different UV lamps were utilized: 15 Watt low pressure (LP) and 150 Watt medium pressure (MP). Results of the study showed that the UV/H(2)O(2) process removed more than 90% of MTBE in 20 minutes when the MP lamp was used at an MTBE/H(2)O(2) molar ratio of 1:200. The results also showed that groundwater sources with higher levels of radical scavengers such as alkalinity, bromide, nitrate and sulfate showed lower rate of MTBE removal. PMID:19844063

  20. Photodynamic Therapy with Hexa(sulfo-n-butyl)[60]Fullerene Against Sarcoma In Vitro and In Vivo.

    PubMed

    Yu, Chi; Avci, Pinar; Canteenwala, Taizoon; Chiang, Long Y; Chen, Bao J; Hamblin, Michael R

    2016-01-01

    The hydrophilic molecular micellar hexa(sulfo-n-butyl)[60]fullerene (FC₄S), first synthesized in 1998 as a photosensitizer (PS) has been reported to exhibit high efficacy for singlet oxygen generation and antimicrobial photodynamic inactivation. The purpose of this study was to investigate the effects of photoactivated FC₄S for free radical generation and to mediate photodynamic therapy (PDT) of cancer in vitro and in vivo. The results demonstrated that following light irradiation, FC4S produced singlet oxygen, but after addition of electron donors such as ferrocytochrome c or NADH, FC4S also produced superoxide. The combination of FC4S with light irradiation was able to induce cytotoxicity to human fibrosarcoma cells and murine sarcoma 180 cells in vitro. Cell-killing was proportional to fluence as well as FC4S concentration. Photoirradiation by argon-ion laser after intraperitoneal injection of FC4S also resulted in inhibition of S180 tumor growth in vivo (up to 80% reduction of tumor volume). Hematological and blood biochemistry parameters of the cancer-bearing mice were improved by PDT. Based on these findings, we conclude that FC₄S has a great potential as a nanomedicine in PDT for cancer. PMID:27398442

  1. Construction of wettability gradient surface on copper substrate by controlled hydrolysis of poly(methyl methacrylate-butyl acrylate) films

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Cheng, Jiang; Yang, Zhuo-ru

    2014-10-01

    We report a gradient wettability surface on copper slide prepared by a simple controlled ester group hydrolysis procedure of poly(methyl methacrylate-butyl acrylate) [P (MMA-BA)] films coated on the copper substrate. In the method, sodium hydroxide solutions are selected to prepare surface gradient wettability on P (MMA-BA) films. The P (MMA-BA) copolymers with different MMA contents are first synthesized by a conventional free atom radical solution polymerization method. The transfer of surface chemical composition from the ester group to acid salt is achieved by hydrolysis in NaOH solution. The effects of different concentrations of NaOH solution and reaction times on the physicochemical properties of the resulting surfaces are studied. The field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) results show that the varying concentration along the substrate length is only attributed to the hydrolysis reaction of ester groups. The hydrolysis causes insignificant change on the morphology of the original film on the copper substrate. In addition, it is found that the MMA copolymer content has a significant influence on the concentration of ester groups on the outermost surface and thus important for forming the slope gradients.

  2. Induction of cell proliferation in the rat liver by the short-term administration of ethyl tertiary-butyl ether

    PubMed Central

    Kakehashi, Anna; Hagiwara, Akihiro; Imai, Norio; Wei, Min; Fukushima, Shoji; Wanibuchi, Hideki

    2015-01-01

    In the present study, in continuation of our previous experiment in order to investigate the mode of action (MOA) of ethyl tertiary-butyl ether (ETBE) hepatotumorigenicity in rats, we aimed to examine alterations in cell proliferation, that are induced by short-term administration of ETBE. F344 rats were administered ETBE at doses of 0, and 1,000 mg/kg body weight twice a day by gavage for 3, 10, 17 and 28 days. It was found that the previously observed significant increase of P450 total content and hydroxyl radical levels after 7 days of ETBE administration, and 8-OHdG formation at day 14, accompanied by accumulation of CYP2B1/2B2, CYP3A1/3A2, CYP2C6, CYP2E1 and CYP1A1 and downregulation of DNA oxoguanine glycosylase 1, was preceded by induction of cell proliferation at day 3. Furthermore, we observed an increase in regenerative cell proliferation as a result of ETBE treatment at day 28, followed by induction of cell cycle arrest and apoptosis by day 14. These results indicated that short-term administration of ETBE led to a significant early increase in cell proliferation activity associated with induction of oxidative stress, and to a regenerative cell proliferation as an adaptive response, which could contribute to the hepatotumorigenicity of ETBE in rats. PMID:26023258

  3. Review of the mutagenicity/genotoxicity of butylated hydroxytoluene.

    PubMed

    Bomhard, E M; Bremmer, J N; Herbold, B A

    1992-09-01

    Butylated hydroxytoluene (BHT) is an effective, widely used, low cost antioxidant. A host of studies examining the potential of BHT to cause point mutations have been published. They include in vitro studies on various bacterial species and strains and on various types of mammalian cell lines as well as in vivo studies on Drosophila melanogaster, silk worms and also the mouse specific locus test (involving long-term exposure). Together these studies convincingly show the absence of a potential for BHT to cause point mutations. A great number of studies on many cell types and species have also been carried out to examine the potential of BHT to cause chromosome aberrations. In vitro studies have been published using plant cells and the WI-38, CHL, CHO, and V79 mammalian cell lines. In vivo studies have been carried out on somatic and/or germ cells of Drosophila melanogaster, rats and mice. Nearly all studies, especially those using validated test systems, indicate that BHT lacks clastogenic potential. In vitro studies on bacterial, yeast and various mammalian cell lines including DON, CHO, CHL cells and primary hepatocytes demonstrate the absence of interactions with or damage to DNA. Taking all the existing data into account, the weight of evidence suggests that BHT does not represent a relevant mutagenic/genotoxic risk to man. PMID:1381049

  4. Strategies for production of butanol and butyl-butyrate through lipase-catalyzed esterification.

    PubMed

    Xin, Fengxue; Basu, Anindya; Yang, Kun-Lin; He, Jianzhong

    2016-02-01

    In this study, a fermentation process for production of butanol and butyl-butyrate by using Clostridium sp. strain BOH3 is developed. This strain is able to produce butyric acid and butanol when it ferments 60 g/L xylose. Meanwhile, it also excreted indigenous lipases (induced by olive oil) which naturally convert butyric acid and butanol into 1.2 g/L of butyl-butyrate. When Bio-OSR was used as both an inducer for lipase and extractant for butyl-butyrate, the butyl-butyrate concentration can reach 6.3 g/L. To further increase the yield, additional lipases and butyric acid are added to the fermentation system. Moreover, kerosene was used as an extractant to remove butyl-butyrate in situ. When all strategies are combined, 22.4 g/L butyl-butyrate can be produced in a fed-batch reactor spiked with 70 g/L xylose and 7.9 g/L butyric acid, which is 4.5-fold of that in a similar system (5 g/L) with hexadecane as the extractant. PMID:26710347

  5. Synthesis, Radical Reactivity, and Thermochemistry of Monomeric Cu(II) Alkoxide Complexes Relevant to Cu/Radical Alcohol Oxidation Catalysis.

    PubMed

    Porter, Thomas R; Capitao, Dany; Kaminsky, Werner; Qian, Zhaoshen; Mayer, James M

    2016-06-01

    Two new monomeric Cu(II) alkoxide complexes were prepared and fully characterized as models for intermediates in copper/radical mediated alcohol oxidation catalysis: Tp(tBuR)Cu(II)OCH2CF3 with Tp(tBu) = hydro-tris(3-tert-butyl-pyrazol-1-yl)borate 1 or Tp(tBuMe) = hydro-tris(3-tert-butyl-5-methyl-pyrazol-1-yl)borate 2. These complexes were made as models for potential intermediates in enzymatic and synthetic catalytic cycles for alcohol oxidation. However, the alkoxide ligands are not readily oxidized by loss of H; instead, these complexes were found to be hydrogen atom acceptors. They oxidize the hydroxylamine TEMPOH, 2,4,6-tri-t-butylphenol, and 1,4-cyclohexadiene to the nitroxyl radical, phenoxyl radical, and benzene, with formation of HOCH2CF3 (TFE) and the Cu(I) complexes Tp(tBuR)Cu(I)-MeCN in dichloromethane/1% MeCN or 1/2 [Tp(tBuR)Cu(I)]2 in toluene. On the basis of thermodynamics and kinetics arguments, these reactions likely proceed through concerted proton-electron transfer mechanisms. Thermochemical analyses give lower limits for the "effective bond dissociation free energies (BDFE)" of the O-H bonds in 1/2[Tp(tBuR)Cu(I)]2 + TFE and upper limits for the free energies associated with alkoxide oxidations via hydrogen atom transfer (effective alkoxide α-C-H BDFEs). These values are summations of the free energies of multiple chemical steps, which include the energetically favorable formation of 1/2[Tp(tBuR)Cu(I)]2. The effective alkoxide α-C-H bonds are very weak, BDFE ≤ 38 ± 4 kcal mol(-1) for 1 and ≤44 ± 5 kcal mol(-1) for 2 (gas-phase estimates), because C-H homolysis is thermodynamically coupled to one electron transfer to Cu(II) as well as the favorable formation of the 1/2[Tp(tBuR)Cu(I)]2 dimer. Treating 1 with the H atom acceptor (t)Bu3ArO(•) did not result in the expected alkoxide oxidation to an aldehyde, but rather net 2,2,2-trifluoroethoxyl radical transfer occurred to generate an unusual 2-substituted dienone-ether product. Treating 2

  6. Students' Ideas and Radical Constructivism

    ERIC Educational Resources Information Center

    Sánchez Gómez, Pedro J.

    2016-01-01

    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…

  7. Robot-assisted radical cystectomy.

    PubMed

    Kurpad, Raj; Woods, Michael

    2015-12-01

    Robot-assisted radical cystectomy (RARC) has rapidly penetrated the field of urology since its inception in 2003. Several observational studies, retrospective reports, and three randomized controlled trials (RCT) have preliminarily demonstrated the safety and efficacy of (RARC). Additionally, results from the RAZOR RCT will be available in 2016-2017 to better substantiate the use of (RARC). PMID:26310514

  8. Free radicals, antioxidants, and nutrition.

    PubMed

    Fang, Yun-Zhong; Yang, Sheng; Wu, Guoyao

    2002-10-01

    Radiation hazards in outer space present an enormous challenge for the biological safety of astronauts. A deleterious effect of radiation is the production of reactive oxygen species, which result in damage to biomolecules (e.g., lipid, protein, amino acids, and DNA). Understanding free radical biology is necessary for designing an optimal nutritional countermeasure against space radiation-induced cytotoxicity. Free radicals (e.g., superoxide, nitric oxide, and hydroxyl radicals) and other reactive species (e.g., hydrogen peroxide, peroxynitrite, and hypochlorous acid) are produced in the body, primarily as a result of aerobic metabolism. Antioxidants (e.g., glutathione, arginine, citrulline, taurine, creatine, selenium, zinc, vitamin E, vitamin C, vitamin A, and tea polyphenols) and antioxidant enzymes (e.g., superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidases) exert synergistic actions in scavenging free radicals. There has been growing evidence over the past three decades showing that malnutrition (e.g., dietary deficiencies of protein, selenium, and zinc) or excess of certain nutrients (e.g., iron and vitamin C) gives rise to the oxidation of biomolecules and cell injury. A large body of the literature supports the notion that dietary antioxidants are useful radioprotectors and play an important role in preventing many human diseases (e.g., cancer, atherosclerosis, stroke, rheumatoid arthritis, neurodegeneration, and diabetes). The knowledge of enzymatic and non-enzymatic oxidative defense mechanisms will serve as a guiding principle for establishing the most effective nutrition support to ensure the biological safety of manned space missions. PMID:12361782

  9. Radical Coupling Mechanisms in Lignification

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The mechansim by which lignification, the polymerization process by which lignins are formed, is via combinatorial radical coupling reactions. Understanding such reactions allows the range of structures in lignins to be understood, and the ability of lignins to accommodate various phenolic precursor...

  10. The Other Women: Radicalizing Feminism.

    ERIC Educational Resources Information Center

    Puigvert, Lidia; Darder, Antonia; Merrill, Barbara; de los Reyes, Eileen; Stromquist, Nelly

    A recent international symposium on radicalizing feminism explored ways of developing a dialogic feminism that emphasizes working in different settings under the common goal of including women who have been invisible in the dominant feminist literature by furthering theories and practices based on the principles of dialogic feminism. The seminar…

  11. Dimeric phenalenyl-based neutral radical molecular conductors.

    PubMed

    Chi, X; Itkis, M E; Kirschbaum, K; Pinkerton, A A; Oakley, R T; Cordes, A W; Haddon, R C

    2001-05-01

    We report the preparation, crystallization, and solid-state characterization of ethyl (3)- and butyl (4)-substituted spiro-biphenalenyl radicals. Both of these compounds are found to be conducting face-to-face pi-dimers in the solid state but with different room-temperature magnetic ground states. At room temperature, 4 exists as a diamagnetic pi-dimer (interplanar separation of approximately 3.1 A), whereas 3 is a paramagnetic pi-dimer (interplanar separation of approximately 3.3 A), and both compounds show phase transitions between the paramagnetic and diamagnetic forms. Electrical resistivity measurements of single crystals of 3 and 4 show that the transition from the high-temperature paramagnetic pi-dimer form to the low-temperature diamagnetic pi-dimer structure is accompanied by an increase in conductivity by about 2 orders of magnitude. This behavior is unprecedented and is very difficult to reconcile with the usual understanding of a Peierls dimerization, which inevitably leads to an insulating ground state. We tentatively assign the enhancement in the conductivity to a decrease in the on-site Coulombic correlation energy (U), as the dimers form a super-molecule with twice the amount of conjugation. PMID:11457155

  12. Trichloroethylene radicals generated by ionizing radiation. An EPR/spin trapping study.

    PubMed

    Carmichael, A J; Steel-Goodwin, L

    1997-06-01

    Trichloroethylene (TCE) was exposed in the presence of the spin trap N-tert-butyl-alpha-phenyl nitrone (PBN, 0.1 M) to ionizing radiation from two different sources in an attempt to determine the origin of the spin-trapped radicals generating the EPR spectra in precision cut liver slices. TCE samples were irradiated with 18 MeV electrons to a total dose of 1000 Gy in a linear accelerator (LINAC) or exposed to 60Co gamma-rays to total doses of 100 Gy and 1000 Gy. The results show that three PBN adducts were generated during the LINAC radiations. Two of these spin adducts correspond to the addition of carbon-centered radicals to PBN, and the third adduct is consistent with a decomposition product of PBN. The predominant carbon-entered radical yields a PBN adduct that is more stable, persists for over 24 h and has identical hyperfine coupling constants (aN = 1.61 mT, aH beta = 0.325 mT) to the PBN adduct obtained when precision-cut liver slices were exposed to TCE. Gamma radiation (100 Gy) of TCE yields PBN adducts with lower primary nitrogen hyperfine coupling constants (aN = 1.45 mT and aN = 1.54 mT). The results (gamma-radiation) suggest that the carbon-centered radical is formed on a single TCE carbon that is different than the predominant radical formed during LINAC radiations. This difference is confirmed by experiments using 13C-TCE. The results further suggest that, during gamma-radiation of TCE, the radicals are formed by dechlorination at the TCE carbon containing two chlorine atoms. The results obtained during LINAC radiations suggest that the predominant radical is formed by dechlorination at the TCE carbon containing a single chlorine and a single proton. In addition, it is possible that this radical is the initial TCE radical formed during exposure of liver slices to TCE. PMID:9219030

  13. Infectious Morbidity After Radical Vulvectomy

    PubMed Central

    Carson, Linda F.; Brooker, Doris C.; Carter, Jonathan R.; Twiggs, Leo B.

    1994-01-01

    Objective: This retrospective investigation describes the infectious morbidity of patients following radical vulvectomy with or without inguinal lymph node dissection. Methods: The charts of patients undergoing radical vulvectomy between January 1, 1986, and September 1, 1989, were reviewed for age, weight, cancer type, tumor stage, operative procedure(s), prophylactic antibiotic and its length of use, febrile morbidity, infection site, culture results, significant medical history, and length of use and number of drains or catheters used. Results: The study group was composed of 61 patients, 14 of whom underwent a radical vulvectomy and 47 who also had inguinal lymph node dissection performed. Twenty-nine patients (48%) had at least 1 postoperative infection. Five patients (8%) had 2 or more postoperative infections. The site and incidence of the infections were as follows: urinary tract 23%, wound 23%, lymphocyst 3%, lymphatics (lymphangitis) 5%, and bowel (pseudomembranous colitis) 3%. The most common pathogens isolated from both urine and wound sites were Pseudomonas aeruginosa, enterococcus, and Escherichia coli. A significant decrease in wound infection was demonstrated when separate incisions were made for inguinal lymph node dissection (P <0.05). The mean number of days to onset of postoperative infection for wound, urine, lymphatics, lymphocyst, and bowel were 11, 8, 57, 48, and 5, respectively. Conclusions: We conclude that the clinical appearance of post-radical vulvectomy infections is delayed when compared with other post-surgical wound infections. Second, utilizing separate inguinal surgical incisions may reduce infectious morbidity. Finally, tumor stage and type do not necessarily increase the infectious morbidity of radical vulvar surgery. PMID:18475379

  14. Formation and characterization of Co(III)-semiquinonate phenoxyl radical species.

    PubMed

    Shimazaki, Yuichi; Kabe, Ryota; Huth, Stefan; Tani, Fumito; Naruta, Yoshinori; Yamauchi, Osamu

    2007-07-23

    Co(III) complexes of N(3)O-donor tripodal ligands, 2,4-di(tert-butyl)-6-{[bis(2-pyridyl)methyl]aminomethyl}phenolate (tbuL), 2,4-di(tert-butyl)-6-{[bis(6-methyl-2-pyridyl)methyl]aminomethyl}phenolate (tbuL(Mepy)(2)), were prepared, and precursor Co(II) complexes, [Co(tbuL)Cl] (1) and [Co(tbuL(Mepy)(2))Cl] (2), and ternary Co(III) complexes, [Co(tbuL)(acac)]ClO(4) (3), [Co(tbuL)(tbu-cat)] (4), and [Co(tbuL(Mepy)(2))(tbu-SQ)]ClO(4) (5), where acac, tbu-cat, and tbu-SQ refer to pentane-2,4-dionate, 3,5-di(tert-butyl)catecholate, and 3,5-di(tert-butyl)semiquinonate, respectively, were structurally characterized by the X-ray diffraction method. Complexes 3 and 5 have a mononuclear structure with a fac-N(3)O(3) donor set, while 4 has a mer-N(3)O(3) structure. The cyclic voltammogram (CV) of complex 3 exhibited one reversible redox wave centered at 0.93 V (vs Ag/AgCl) in CH(3)CN. Complex 5 was converted to a phenoxyl radical species upon oxidation with Ce(IV), showing a characteristic pi-pi* transition band at 412 nm. The ESR spectrum at low temperature and the resonance Raman spectrum of 3 established that the radical species has a Co(III)-phenoxyl radical bond. On the other hand, the CVs showed two oxidation processes at E(1/2) = 0.01 and E(pa) = 0.92 V for 4 and E(1/2a) = 0.05 and E(1/2b) = 0.69 V for 5. The rest potential of 4 (-0.11 V) was lower than the E(1/2) value, whereas that of 5 (0.18 V) was higher, indicating that the first redox wave of 4 and 5 is assigned to the tbu-cat and the tbu-SQ redox process, respectively. One-electron oxidized 4 showed absorption, resonance Raman, and ESR spectra which are similar to those of 5, suggesting formation of a stable Co(III)-semiquinonate species, which has the same oxidation level of 5. The resonance Raman spectrum of two-electron oxidized 4 showed the nu(8a) bands of the semiquinonate and phenoxyl radical, which were absent in the spectrum of one-electron oxidized 5. Since both oxidized species were ESR inactive at 5 K

  15. Purification and in vitro antioxidative effects of giant squid muscle peptides on free radical-mediated oxidative systems.

    PubMed

    Rajapakse, Niranjan; Mendis, Eresha; Byun, Hee-Guk; Kim, Se-Kwon

    2005-09-01

    Low molecular weight peptides obtained from ultrafiltration (UF) of giant squid (Dosidicus gigas) muscle protein were studied for their antioxidative effects in different in vitro oxidative systems. The most potent two peptides, Asn-Ala-Asp-Phe-Gly-Leu-Asn-Gly-Leu-Glu-Gly-Leu-Ala (1307 Da) and Asn-Gly-Leu-Glu-Gly-Leu-Lys (747 Da), exhibited their antioxidant potential to act as chain-breaking antioxidants by inhibiting radical-mediated peroxidation of linoleic acid, and their activities were closer to highly active synthetic antioxidant, butylated hydroxytoluene. Addition of these peptides could enhance the viability of cytotoxic embryonic lung fibroblasts significantly (P<.05) at a low concentration of 50 microg/ml, and it was presumed due to the suppression of radical-induced oxidation of membrane lipids. Electron spin trapping studies revealed that the peptides were potent scavengers of free radicals in the order of carbon-centered (IC(50) 396.04 and 304.67 microM), hydroxyl (IC(50) 497.32 and 428.54 microM) and superoxide radicals (IC(50) 669.34 and 573.83 microM). Even though the exact molecular mechanism for scavenging of free radicals was unclear, unusually high hydrophobic amino acid composition (more than 75%) of giant squid muscle peptides was presumed to be involved in the observed activities. PMID:16115545

  16. Metabolism of 3-tert-butyl-4-hydroxyanisole to 3-tert-butyl-4,5-dihydroxyanisole by rat liver microsomes.

    PubMed

    Armstrong, K E; Wattenberg, L W

    1985-04-01

    3-tert-Butylhydroxyanisole (3-BHA) is an antioxidant which can have a modulating effect on chemical carcinogenesis. Information concerning the metabolism of 3-BHA is incomplete. In the present study, the metabolites formed by incubating 3-BHA with liver microsomes from rats given beta-naphthoflavone by p.o. intubation were studied. Three metabolites were identified, two major metabolites and a minor metabolite. One of the major metabolites was the catechol of 3-BHA, i.e., 3-tert-butyl-4,5-dihydroxyanisole, which has not previously been reported. A characteristic of this compound is its capacity to be oxidized readily. The second major metabolite was tert-butyl hydroquinone which has been reported previously to be a liver microsomal metabolite of 3-BHA. The third metabolite, which occurred in small quantities, was 2,2'-dihydroxy-3,3'-di-tert-butyl-5,5'-dimethoxydiphenyl. 2,2'-Dihydroxy-3,3'-di-tert-butyl-5,5'-dimethoxydiphenyl has been identified previously as a major metabolite of 3-BHA in the rat intestine. An understanding of the metabolism of 3-BHA may assist in elucidating the mechanism(s) of its biological effects. PMID:3978617

  17. Carcinogenicity of methyl-tertiary butyl ether in gasoline.

    PubMed

    Mehlman, Myron A

    2002-12-01

    Methyl tertiary butyl ether (MTBE) was added to gasoline on a nationwide scale in 1992 without prior testing of adverse, toxic, or carcinogenic effects. Since that time, numerous reports have appeared describing adverse health effects of individuals exposed to MTBE, both from inhalation of fumes in the workplace and while pumping gasoline. Leakage of MTBE, a highly water-soluble compound, from underground storage tanks has led to contamination of the water supply in many areas of the United States. Legislation has been passed by many states to prohibit the addition of MTBE to gasoline. The addition of MTBE to gasoline has not accomplished its stated goal of decreasing air pollution, and it has posed serious health risks to a large portion of the population, particularly the elderly and those with respiratory problems, asthma, and skin sensitivity. Reports of animal studies of carcinogenicity of MTBE began to appear in the 1990s, prior to the widespread introduction of MTBE into gasoline. These reports were largely ignored. In ensuing years, further studies have shown that MTBE causes various types of malignant tumors in mice and rats. The National Toxicology Program (NTP) Board of Scientific Counselors' Report on Carcinogens Subcommittee met in December 1998 to consider listing MTBE as "reasonably anticipated to be a human carcinogen." In spite of recommendations from Dr. Bailer, the primary reviewer, and other scientists on the committee, the motion to list MTBE in the report was defeated by a six to five vote, with one abstention. On the basis of animal studies, it is widely accepted that if a chemical is carcinogenic in appropriate laboratory animal test systems, it must be treated as though it were carcinogenic in humans. In the face of compelling evidence, NTP Committee members who voted not to list MTBE as "reasonably anticipated to be a human carcinogen" did a disservice to the general public; this action may cause needless exposure of many to health risks

  18. Effects of simulant mixed waste on EPDM and butyl rubber

    SciTech Connect

    Nigrey, P.J.; Dickens, T.G.

    1997-11-01

    The authors have developed a Chemical Compatibility Testing Program for the evaluation of plastic packaging components which may be used in transporting mixed waste forms. In this program, they have screened 10 plastic materials in four liquid mixed waste simulants. These plastics were butadiene-acrylonitrile copolymer (Nitrile) rubber, cross-linked polyethylene, epichlorohydrin rubber, ethylene-propylene (EPDM) rubber, fluorocarbons (Viton and Kel-F{trademark}), polytetrafluoro-ethylene (Teflon), high-density polyethylene, isobutylene-isoprene copolymer (Butyl) rubber, polypropylene, and styrene-butadiene (SBR) rubber. The selected simulant mixed wastes were (1) an aqueous alkaline mixture of sodium nitrate and sodium nitrite; (2) a chlorinated hydrocarbon mixture; (3) a simulant liquid scintillation fluid; and (4) a mixture of ketones. The screening testing protocol involved exposing the respective materials to approximately 3 kGy of gamma radiation followed by 14-day exposures to the waste simulants at 60 C. The rubber materials or elastomers were tested using Vapor Transport Rate measurements while the liner materials were tested using specific gravity as a metric. The authors have developed a chemical compatibility program for the evaluation of plastic packaging components which may be incorporated in packaging for transporting mixed waste forms. From the data analyses performed to date, they have identified the thermoplastic, polychlorotrifluoroethylene, as having the greatest chemical compatibility after having been exposed to gamma radiation followed by exposure to the Hanford Tank simulant mixed waste. The most striking observation from this study was the poor performance of polytetrafluoroethylene under these conditions. In the evaluation of the two elastomeric materials they have concluded that while both materials exhibit remarkable resistance to these environmental conditions, EPDM has a greater resistance to this corrosive simulant mixed waste.

  19. Transcatheter Embolotherapy with N-Butyl Cyanoacrylate for Ectopic Varices

    SciTech Connect

    Choi, Jin Woo; Kim, Hyo-Cheol Jae, Hwan Jun Jung, Hyun-Seok; Hur, Saebeom; Lee, Myungsu; Chung, Jin Wook

    2015-04-15

    PurposeTo address technical feasibility and clinical outcome of transcatheter embolotherapy with N-butyl cyanoacrylate (NBCA) for bleeding ectopic varices.MethodsThe institutional review board approved this retrospective study and waived informed consent. From January 2004 to June 2013, a total of 12 consecutive patients received transcatheter embolotherapy using NBCA for bleeding ectopic varices in our institute. Clinical and radiologic features of the endovascular procedures were comprehensively reviewed.ResultsPreprocedural computed tomography images revealed ectopic varices in the jejunum (n = 7), stoma (n = 2), rectum (n = 2), and duodenum (n = 1). The 12 procedures consisted of solitary embolotherapy (n = 8) and embolotherapy with portal decompression (main portal vein stenting in 3, transjugular intrahepatic portosystemic shunt in 1). With regard to vascular access, percutaneous transhepatic access (n = 7), transsplenic access (n = 4), and transjugular intrahepatic portosystemic shunt tract (n = 1) were used. There was no failure in either the embolotherapy or the vascular accesses (technical success rate, 100 %). Two patients died within 1 month from the procedure from preexisting fatal medical conditions. Only one patient, with a large varix that had been partially embolized by using coils and NBCA, underwent rebleeding 5.5 months after the procedure. The patient was retreated with NBCA and did not undergo any bleeding afterward for a follow-up period of 2.5 months. The remaining nine patients did not experience rebleeding during the follow-up periods (range 1.5–33.2 months).ConclusionTranscatheter embolotherapy using NBCA can be a useful option for bleeding ectopic varices.

  20. Electron attachment to fluorocarbon radicals

    NASA Astrophysics Data System (ADS)

    Shuman, Nicholas

    2014-10-01

    Most plasma environments contain populations of short-lived species such as radicals, the chemistry of which can have significant effects on the overall chemistry of the system. However, few experimental measurements of the kinetics of electron attachment to radicals exist due to the inherent difficulties of working with transient species. Calculations from first principles have been attempted, but are arduous and, because electron attachment is so sensitive to the specifics of the potential surface, their accuracy has not been established. Electron attachment to small fluorocarbon radicals is particularly important, as the data are needed for predictive modeling of plasma etching of semiconductor materials, a key process in the industrial fabrication of microelectronics. We have recently developed a novel flowing afterglow technique to measure several types of otherwise difficult to study plasma processes, including thermal electron attachment to radicals. Variable Electron and Neutral Density Attachment Mass Spectrometry (VENDAMS) exploits dissociative electron attachment in a weakly ionized plasma as a radical source. Here, we apply VENDAMS to a series of halofluorocarbon precursors in order to measure the kinetics of thermal electron attachment to fluorocarbon radicals. Results are presented for CF2, CF3, C2F5,C2F3,1-C3F7, 2-C3F7, and C3F5 from 300 K to 900 K. Both the magnitude and the temperature dependences of rate coefficients as well as product branching between associative and dissociative attachment are highly system specific; however, thermal attachment to all species is inefficient, never exceeding 5% of the collision rate. The data are analyzed using a recently developed kinetic modeling approach, which uses extended Vogt-Wannier theory as a starting point, accounts for dynamic effects such as coupling between the electron and nuclear motions through empirically validated functional forms, and finally uses statistical theory to determine the fate of

  1. Radical Puppets and the Language of Art

    ERIC Educational Resources Information Center

    Asher, Rikki

    2009-01-01

    Radical puppets are puppets with a social message. Radical puppets encourage creative ideas that lead toward understanding global and environmental aspects of society through the "art of the puppet," a phrase coined by American puppeteer Bill Baird (1965). There is a blending of performance and visual art in puppetry. Through radical puppetry,…

  2. Free-radical chemistry of sulfite.

    PubMed Central

    Neta, P; Huie, R E

    1985-01-01

    The free-radical chemistry of sulfite oxidation is reviewed. Chemical transformations of organic and biological molecules induced by sulfite oxidation are summarized. The kinetics of the free-radical oxidations of sulfite are discussed, as are the kinetics of the reactions of the sulfite-derived radicals SO3 and the peroxy derivative SO5 with organic compounds. PMID:3830699

  3. Batch-injection analysis with amperometric detection of the DPPH radical for evaluation of antioxidant capacity.

    PubMed

    Oliveira, Gracy K F; Tormin, Thiago F; Sousa, Raquel M F; de Oliveira, Alberto; de Morais, Sérgio A L; Richter, Eduardo M; Munoz, Rodrigo A A

    2016-02-01

    This work proposes the application of batch-injection analysis with amperometric detection to determine the antioxidant capacity of real samples based on the measurement of DPPH radical consumption. The efficient concentration or EC50 value corresponds to the concentration of sample or standard required to scavenge 50% DPPH radicals. For the accurate determination of EC50, samples were incubated with DPPH radical for 1h because many polyphenolic compounds typically found in plants and responsible for the antioxidant activity exhibit slow kinetics. The BIA system with amperometric detection using a glassy-carbon electrode presented high precision (RSD = 0.7%, n = 12), low detection limit (1 μmol L(-1)) and selective detection of DPPH (free of interferences from antioxidants). These contributed to low detection limits for the antioxidant (0.015 and 0.19 μmol L(-1) for gallic acid and butylated hydroxytoluene, respectively). Moreover, BIA methods show great promise for portable analysis because battery-powered instrumentation (electronic micropipette and potentiostats) is commercially available. PMID:26304399

  4. Markers of protein oxidation by hydroxyl radical and reactive nitrogen species in tissues of aging rats.

    PubMed

    Leeuwenburgh, C; Hansen, P; Shaish, A; Holloszy, J O; Heinecke, J W

    1998-02-01

    Many lines of evidence implicate oxidative damage in aging. Possible pathways include reactions that modify aromatic amino acid residues on proteins. o-Tyrosine is a stable marker for oxidation of protein-bound phenylalanine by hydroxyl radical, whereas 3-nitrotyrosine is a marker for oxidation of protein-bound tyrosine by reactive nitrogen species. To test the hypothesis that proteins damaged by hydroxyl radical and reactive nitrogen accumulate with aging, we used isotope dilution gas chromatography-mass spectrometry to measure levels of o-tyrosine and 3-nitrotyrosine in heart, skeletal muscle, and liver from young adult (9 mo) and old (24 mo) female Long-Evans/Wistar hybrid rats. We also measured these markers in young adult and old rats that received antioxidant supplements (alpha-tocopherol, beta-carotene, butylated hydroxytoluene, and ascorbic acid) from the age of 5 mo. We found that aging did not significantly increase levels of protein-bound o-tyrosine or 3-nitrotyrosine in any of the tissues. Antioxidant supplementation had no effect on the levels of protein-bound o-tyrosine and 3-nitrotyrosine in either young or old animals. These observations indicate that the o-tyrosine and 3-nitrotyrosine do not increase significantly in heart, skeletal muscle, and liver in old rats, suggesting that proteins damaged by hydroxyl radical and reactive nitrogen species do not accumulate in these tissues with advancing age. PMID:9486304

  5. Radical scavenging and anti-lipoperoxidative activities of Smallanthus sonchifolius leaf extracts.

    PubMed

    Valentová, Katerina; Sersen, Frantisek; Ulrichová, Jitka

    2005-07-13

    Radical scavenging and anti-lipoperoxidative effects of two organic fractions and two aqueous extracts from the leaves of a neglected Andean crop-yacon (Smallanthus sonchifolius Poepp. & Endl., Asteraceae) were determined using various in vitro models. The extracts' total phenolic content was 10.7-24.6%. They exhibited DPPH (IC50 16.14-33.39 microg/mL) and HO* scavenging activities (4.49-6.51 mg/mL). The extracts did not scavenge phenylglyoxylic ketyl radicals, but they retarded their formation. In the xanthine/xanthine oxidase superoxide radical generating system, the extracts' activities were 26.10-37.67 superoxide dismutase equivalents/mg. As one of the extracts displayed xanthine oxidase inhibitory activity, the effect of the extracts on a nonenzymatically generated superoxide was determined (IC50 7.36-21.01 microg/mL). The extracts inhibited t-butyl hydroperoxide-induced lipoperoxidation of microsomal and mitochondrial membranes (IC50 22.15-465.3 microg/mL). These results make yacon leaves a good candidate for use as a food supplement in the prevention of chronic diseases involving oxidative stress. PMID:15998117

  6. Peroxyl Radical Reactions in Water Solution: A Gym for Proton-Coupled Electron-Transfer Theories.

    PubMed

    Amorati, Riccardo; Baschieri, Andrea; Morroni, Gloria; Gambino, Rossana; Valgimigli, Luca

    2016-06-01

    The reactions of alkylperoxyl radicals with phenols have remained difficult to investigate in water. We describe herein a simple and reliable method based on the inhibited autoxidation of water/THF mixtures, which we calibrated against pulse radiolysis. With this method we measured the rate constants kinh for the reactions of 2-tetrahydrofuranylperoxyl radicals with reference compounds: urate, ascorbate, ferrocenes, 2,2,5,7,8-pentamethyl-6-chromanol, Trolox, 6-hydroxy-2,5,7,8-tetramethylchroman-2-acetic acid, 2,6-di-tert-butyl-4-methoxyphenol, 4-methoxyphenol, catechol and 3,5-di-tert-butylcatechol. The role of pH was investigated: the value of kinh for Trolox and 4-methoxyphenol increased 11- and 50-fold from pH 2.1 to 12, respectively, which indicate the occurrence of a SPLET-like mechanism. H(D) kinetic isotope effects combined with pH and solvent effects suggest that different types of proton-coupled electron transfer (PCET) mechanisms are involved in water: less electron-rich phenols react at low pH by concerted electron-proton transfer (EPT) to the peroxyl radical, whereas more electron-rich phenols and phenoxide anions react by multi-site EPT in which water acts as proton relay. PMID:27111024

  7. Antioxidant, Antimicrobial, and Free Radical Scavenging Potential of Aerial Parts of Periploca aphylla and Ricinus communis

    PubMed Central

    Iqbal, Jamshed; Zaib, Sumera; Farooq, Umar; Khan, Afsar; Bibi, Irum; Suleman, Saba

    2012-01-01

    Context. Many diseases are associated with oxidative stress caused by free radicals. Objective. The present study evaluated the in vitro antioxidant and antibacterial activities of various extracts of aerial parts of Periploca aphylla and Ricinus communis. Materials and Methods. In vitro antioxidant activities of the plant extract were determined by DPPH and NO scavenging method. Superoxide anion radical activity was measured by the reduction of nitro blue tetrazolium as compared with standard antioxidants. Total phenolic contents and antibacterial activities of these plants were determined by gallic acid equivalent (GAE) and serial tube dilution method, respectively. Results. Plants showed significant radical scavenging activity. The results were expressed as IC50. n-Propyl gallate and 3-t-butyl-4-hydroxyanisole were used as standards for antioxidant assay. All the extracts of both plants showed comparable IC50 to those of standards. Plants extract exhibited high phenolic contents and antibacterial activities were comparable with standard drug, Ciprofloxacin. Discussion and Conclusion. The present study provides evidence that Periploca aphylla and Ricinus communis prove to be potent natural antioxidants and could replace synthetic antioxidants. Plants can also be used against pathogenic bacterial strains. PMID:22919511

  8. [Erectile rehabilitation after radical prostatectomy].

    PubMed

    Droupy, S; Giuliano, F; Costa, P

    2009-12-01

    The concept of penile rehabilitation involves the procedures designed to improve oxygen delivery the penile erectile tissue to minimized tissue damage during the period of neural recovery following radical prostatectomy. Many basic research studies support the rationale and mechanism of the concept of penile rehabilitation, however they are few clinical studies in the literature that provide a clear medical evidence of its efficacy in patients. Waiting for new data, it is recommended to propose to the patients, following a radical prostatectomy, an active pharmacological penile rehabilitation. This rehabilitation involves counselling with the couple to have regular sexual activities, ideally 1 to 3 times a week. Penile erections could be induced by intracavernosal injections of PGE1 or improved by using PDE5 inhibitors on demand. The results of daily use of PDE5 inhibitor are conflicting and then it cannot be recommended systematically waiting for new data. The rehabilitation could be maintained for about 2 years as results improve with time. PMID:20123519

  9. Mutagenicity of Oxygen Free Radicals

    NASA Astrophysics Data System (ADS)

    Moody, Carmella S.; Hassan, Hosni M.

    1982-05-01

    Paraquat 1,1'-dimethyl-4,4'-bipyridinium dichloride) was used as an intracellular generator of oxygen free radicals and was found to be highly mutagenic for Salmonella typhimurium. It caused both base-pair substitution and frameshift mutations. Paraquat was much more toxic and mutagenic in a simple nutritionally restricted medium than in a rich complex medium. The mutagenicity of paraquat was dependent upon the presence of a supply of both electrons and oxygen. Cells containing high levels of superoxide dismutase (superoxide:superoxide oxidoreductase, EC 1.15.1.1) were more resistant to the toxicity and the mutagenicity of paraquat than were cells containing normal levels of this enzyme. The mutagenicity of paraquat thus appears to be due to its ability to exacerbate the intracellular production of superoxide radicals.

  10. Geoscientists and the Radical Middle

    NASA Astrophysics Data System (ADS)

    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. Radical Smiles Rearrangement: An Update.

    PubMed

    Allart-Simon, Ingrid; Gérard, Stéphane; Sapi, Janos

    2016-01-01

    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. PMID:27399654

  12. Hydroxyl radical detection in vivo

    SciTech Connect

    Chevion, M.; Floyd, R.A.

    1986-05-01

    Hydroxyl radicals have been implicated as the actual species responsible for the deleterious effects of active oxygen in biology. However, in most cases, its presence has only been inferred by circumstantial evidence. Using electrochemical detection coupled to HPLC separation technique the authors can identify and quantitate (at sub-picomole level) the hydroxylated products of 3 aromatic compounds (phenol, salicylate, and 2-deoxy-guanosine) as a direct measure of hydroxyl radical formation. Firstly, the authors showed that mixing ascorbate with copper ions (in the absence of presence of a protein) yields catechols, dihydroxybenzoic acids and 8-OH-deoxy-guanosine (8-OHdG). This approach has been used to study the formation of OH in vivo. Human granulocytes stimulated with TPA showed that 8-OHdG was formed in the cellular DNA at high levels (one 8-OHdG/800 DNA bases). Unstimulated granulocytes contained 8-OHdG below detection level. Formation of 8-OHdG in the TPA-stimulated granulocytes DNA was decreased by the addition of SOD and catalase. Using salicylate as an in vivo scavenger of hydroxyl radicals the authors showed that the level of trapped-dihydroxybenzoic acids is increased approx.8 and approx.3 fold in the lungs and liver of paraquat-poisoned mice, respectively, as compared to normal animals. Similarly, the detected level of dihydroxybenzoic acids in the hearts of adriamycin-treated rats was increased over 100-fold as compared to the hearts of control animals.

  13. A radical way to burn

    SciTech Connect

    Ashley, S.

    1996-08-01

    By manipulating chamber geometries as well as engine cycle pressures and timing, engineers are exploiting a long-obscure technology known as activated radical combustion. Piston-driven internal combustion engines generally come in two varieties: compression-ignited diesels and spark-ignited gasoline power plants. There, is however, a third way to initiate burning of the fuel-air mixture. The technique--variously called radical ignition (RI), activated radical (AR) combustion, Toyota-Soken combustion, and active thermo-atmosphere combustion--is not exactly new, but only recently have engineers begun to exploit the process in practical power plants. These new units include a lightweight two-stroke racing-motorcycle engine, truck diesels with reduced soot output, and lean-burn spark-ignited car engines. This long-obscure combustion process is based on a range of specialized chemical kinetic and physical acoustic techniques developed over decades. Engineers manipulate fundamental combustion parameter such as chamber geometries, valving and porting configurations, and engine cycle pressures and timing to foster the formation of certain highly reactive chemical species that lower the fuel-air mixture`s flash point so that even modest compression make sit self-ignite. These chemical initiators are then retained into the next cycle to start combustion, allowing the engineer to run stably with no spark.

  14. Radical scavengers from heavy hydrocarbons

    SciTech Connect

    Kubo, Junichi

    1996-10-01

    The hydrogen-donating properties of some hydrocarbons form the basis for processes such as coal liquefaction and heavy oil upgrading. However, these hydrocarbons have seldom been used for other purposes, because their potential applications have not been well recognized. Research has indicated that these hydrogen-donating hydrocarbons can be used in important reactions as radical scavengers and have properties particular to those of pure hydrocarbons without functional groups containing heteroatoms. Over years of study researchers have found that pure hydrocarbons with radical-scavenging effects nearly as high as those in conventional hindered phenolic antioxidants can be produced from petroleum, and these hydrogen-donating hydrocarbons exhibit such effects even in oxidative atmospheres (i.e., they function as antioxidants). He has also shown that these mixtures have some properties particular to pure hydrocarbons without functional groups containing heteroatoms, and they`ve seen that a mechanism based on the steric effects appears when these hydrocarbons are used in heavy oil hydroprocessing. Hydrogen-donating hydrocarbons should be a viable resource in many applications. In this article, he presents radical-scavenging abilities, characteristics as pure hydrocarbons, and applications on the basis of the studies.

  15. Simultaneous Clostridial fermentation, lipase-catalyzed esterification, and ester extraction to enrich diesel with butyl butyrate.

    PubMed

    van den Berg, Corjan; Heeres, Arjan S; van der Wielen, Luuk A M; Straathof, Adrie J J

    2013-01-01

    The recovery of 1-butanol from fermentation broth is energy-intensive since typical concentrations in fermentation broth are below 20 g L(-1). To prevent butanol inhibition and high downstream processing costs, we aimed at producing butyl esters instead of 1-butanol. It is shown that it is possible to perform simultaneously clostridial fermentation, esterification of the formed butanol to butyl butyrate, and extraction of this ester by hexadecane. The very high partition coefficient of butyl butyrate pulls the esterification towards the product side even at fermentation pH and relatively low butanol concentrations. The hexadecane extractant is a model diesel compound and is nontoxic to the cells. If butyl butyrate enriched diesel can directly be used as car fuel, no product recovery is required. A proof-of-principle experiment for the one-pot bio-ester production from glucose led to 5 g L(-1) butyl butyrate in the hexadecane phase. The principle may be extended to a wide range of esters, especially to longer chain ones. PMID:22833369

  16. The electrospinning of the copolymer of styrene and butyl acrylate for its application as oil absorbent.

    PubMed

    Xu, Naiku; Cao, Jipeng; Lu, Yuyao

    2016-01-01

    Electrospun polystyrene materials have been employed as oil absorbents, but they have visible drawbacks such as poor strength at low temperature and unreliable integrity because of brittleness and insufficient cohesive force among fibers. Butyl acrylate can polymerize into flexible chains, and its polymer can be used as elastomer and adhesive material. Thereby it is possible to obtain the material that has better performance in comparison with electrospun polystyrene material through the electrospinning of the copolymer of styrene and butyl acrylate. In this work, a polymer was synthesized through suspension polymerization by using styrene and butyl acrylate as comonomers. The synthesis of the copolymer of styrene and butyl acrylate was verified through dissolution and hydrolysis experimental data; as well through nuclear magnetic resonance spectrometry. The viscous flow activation energy of the solution consisting of copolymer and N, N-dimethylformamide was determined via viscosity method and then adopted to establish the entanglement characteristics of butyl acrylate's chain segments. Finally, in order to electrospin the copolymer solution into fibrous membrane, the effects of monomer feed ratio and spinning parameters were investigated. The prepared fibrous membrane was found to have a potential use as oil absorbent. PMID:27610302

  17. Radiation-induced degradation of butyl rubber vulcanized by three different crosslinking systems

    NASA Astrophysics Data System (ADS)

    Scagliusi, Sandra R.; Cardoso, Elisabeth C. L.; Lugao, Ademar B.

    2012-08-01

    Butyl rubber (IIR) is an isobutylene/isoprene copolymer and is provided with good properties including low permeability to gases, good thermal stability and high resistance to oxygen and ozone action, among others. It is well known that the major effect of ionizing radiations on butyl rubber is chain scission accompanied with a significant reduction in molar mass. This work aimed to study the effects of gamma radiation on the properties of butyl rubbers vulcanized by three different curing systems, such as, the ones based on sulfur, sulfur donor and phenolic resin to identify which curing system is the most stable under irradiation. The butyl rubber vulcanized by three different systems was gamma irradiated with doses of 25 kGy, 50 kGy, 100 kGy, 150 kGy and 200 kGy. Irradiated and non-irradiated samples were characterized by the following techniques: tensile, elongation and hardness. It was observed that doses higher than 150 kGy practically destroy the assessed properties for all butyl compounds, irrespective of the vulcanization system used; however compounds cured with phenolic resin showed a decrease in properties proportional to the dose.

  18. Non-Specific Inhibition of Ischemia- and Acidosis-Induced Intracellular Calcium Elevations and Membrane Currents by α-Phenyl-N-tert-butylnitrone, Butylated Hydroxytoluene and Trolox

    PubMed Central

    Katnik, Christopher; Cuevas, Javier

    2014-01-01

    Ischemia, and subsequent acidosis, induces neuronal death following brain injury. Oxidative stress is believed to be a key component of this neuronal degeneration. Acute chemical ischemia (azide in the absence of external glucose) and acidosis (external media buffered to pH 6.0) produce increases in intracellular calcium concentration ([Ca2+]i) and inward membrane currents in cultured rat cortical neurons. Two α-tocopherol analogues, trolox and butylated hydroxytoluene (BHT), and the spin trapping molecule α-Phenyl-N-tert-butylnitrone (PBN) were used to determine the role of free radicals in these responses. PBN and BHT inhibited the initial transient increases in [Ca2+]i, produced by ischemia, acidosis and acidic ischemia and increased steady state levels in response to acidosis and the acidic ischemia. BHT and PBN also potentiated the rate at which [Ca2+]i increased after the initial transients during acidic ischemia. Trolox inhibited peak and sustained increases in [Ca2+]i during ischemia. BHT inhibited ischemia induced initial inward currents and trolox inhibited initial inward currents activated by acidosis and acidic ischemia. Given the inconsistent results obtained using these antioxidants, it is unlikely their effects were due to elimination of free radicals. Instead, it appears these compounds have non-specific effects on the ion channels and exchangers responsible for these responses. PMID:24583849

  19. Non-specific inhibition of ischemia- and acidosis-induced intracellular calcium elevations and membrane currents by α-phenyl-N-tert-butylnitrone, butylated hydroxytoluene and trolox.

    PubMed

    Katnik, Christopher; Cuevas, Javier

    2014-01-01

    Ischemia, and subsequent acidosis, induces neuronal death following brain injury. Oxidative stress is believed to be a key component of this neuronal degeneration. Acute chemical ischemia (azide in the absence of external glucose) and acidosis (external media buffered to pH 6.0) produce increases in intracellular calcium concentration ([Ca2+]i) and inward membrane currents in cultured rat cortical neurons. Two α-tocopherol analogues, trolox and butylated hydroxytoluene (BHT), and the spin trapping molecule α-Phenyl-N-tert-butylnitrone (PBN) were used to determine the role of free radicals in these responses. PBN and BHT inhibited the initial transient increases in [Ca2+]i, produced by ischemia, acidosis and acidic ischemia and increased steady state levels in response to acidosis and the acidic ischemia. BHT and PBN also potentiated the rate at which [Ca2+]i increased after the initial transients during acidic ischemia. Trolox inhibited peak and sustained increases in [Ca2+]i during ischemia. BHT inhibited ischemia induced initial inward currents and trolox inhibited initial inward currents activated by acidosis and acidic ischemia. Given the inconsistent results obtained using these antioxidants, it is unlikely their effects were due to elimination of free radicals. Instead, it appears these compounds have non-specific effects on the ion channels and exchangers responsible for these responses. PMID:24583849

  20. Free-radical-mediated DNA binding.

    PubMed Central

    O'Brien, P J

    1985-01-01

    Free-radical metabolites can be generated metabolically by a one-electron reductase-catalyzed reaction or a "peroxidase" catalyzed oxidation or by photoactivation of a wide variety of aromatic xenobiotics. Radicals may also be generated during lipid peroxidation. Some radicals can react with DNA or bind covalently or noncovalently as a dismutation product or as a dimer, trimer or polymeric product. Modification to the DNA can result in single-strand breaks, loss of template activity, and crosslinking. The binding can prevent enzymic digestion. In some cases, the radicals react with oxygen, resulting before conversion to DNA reactive oxygen species. Most radicals probably do not interact with DNA. PMID:3007090

  1. Radical migration-addition of N-tert-butanesulfinyl imines with organozinc reagents.

    PubMed

    Huang, Wei; Ye, Jian-Liang; Zheng, Wei; Dong, Han-Qing; Wei, Bang-Guo

    2013-11-15

    A novel migration-addition sequence was discovered for the reaction of enantioenriched N-tert-butanesulfinyl iminoacetate 1a with functionalized benzylzinc bromide reagents, producing tert-leucine derivatives in excellent diastereoselectivity (dr 98:2). The absolute configurations of two new chiral centers were unambiguously assigned by chemical transformations and X-ray crystallography. In addition, the regio- and diastereoselectivities of this novel reaction were both explained through the key N-sulfinamine intermediate M6 generated by the tert-butyl radical attack on the imine. Computational analysis of this reaction process, which was performed at the B3LYP/6-311++G(3df,2p)//B3LYP/6-31G*-LANL2DZ level, also supported our proposed two-stage mechanism. PMID:24160561

  2. Fluorescent Brighteners as Visible LED-Light Sensitive Photoinitiators for Free Radical Photopolymerizations.

    PubMed

    Zuo, Xiaoling; Morlet-Savary, Fabrice; Graff, Bernadette; Blanchard, Nicolas; Goddard, Jean-Philippe; Lalevée, Jacques

    2016-05-01

    The photochemical and electrochemical investigations of commercially available, safe, and cheap fluorescent brighteners, namely, triazinylstilbene (commercial name: fluorescent brightener 28) and 2,5-bis(5-tert-butyl-benzoxazol-2-yl)thiophene, as well as their original use as photoinitiators of polymerization upon light emitting diode (LED) irradiation are reported. Remarkably, their excellent near-UV-visible absorption properties combined with outstanding fluorescent properties allow them to act as high-performance photoinitiators when used in combination with diaryliodonium salt. These two-component photoinitiating systems can be employed for free radical polymerizations of acrylate. In addition, this brightener-initiated photopolymerization is able to overcome oxygen inhibition even upon irradiation with low LED light intensity. The underlying photochemical mechanisms are investigated by electron-spin resonance-spin trapping, fluorescence, cyclic voltammetry, and steady-state photolysis techniques. PMID:27072016

  3. Contents of methyl-, ethyl-, propyl-, butyl- and benzylparaben in cosmetic products.

    PubMed

    Rastogi, S C; Schouten, A; de Kruijf, N; Weijland, J W

    1995-01-01

    The contents of methyl-, ethyl-, propyl-, butyl- and benzylparaben in 215 cosmetic products have been determined to elucidate the concentration and frequency of use of these parabens in cosmetic products, and to monitor whether the products complied with the Danish and EEC regulations. The results showed that 77% of the products investigated contained 0.01%-0.87% parabens. Nearly all (99%) of the leave-on cosmetics and 77% of rinse-off cosmetics were found to contain parabens. A maximum of 0.32% methyl- and propylparaben, 0.19% ethylparaben, and 0.07% butyl- and benzylparaben were present in paraben-positive cosmetics. A preferential use of methyl-/ethyl-/propyl-/butyl-/benzylparaben in various groups of cosmetic products was revealed. PMID:7720367

  4. In vitro free radical scavenging and antioxidant properties of ethanol extract of Terminalia glaucescens

    PubMed Central

    Olugbami, J. Olorunjuwon; Gbadegesin, Michael A.; Odunola, Oyeronke A.

    2015-01-01

    Background: Reactive oxygen species (ROS) are implicated in various pathological conditions. Synthetic antioxidants have adverse health effects, while many medicinal plants have antioxidant components that can prevent the harmful effects of ROS. Objectives: This study quantitatively determined the total phenolic content (TPC), total flavonoid content (TFC), and antioxidant properties of ethanol extract of the stem bark of Terminalia glaucescens (EESTG). Materials and Methods: The objectives were achieved based on in vitro assays. Data were analyzed by Sigma Plot (version 11.0). Results: Using gallic acid as the standard compound, TPC value obtained was 596.57 μg GAE/mg extract. TFC content of EESTG, determined as quercetin equivalent was 129.58 μg QE/mg extract. Furthermore, EESTG significantly (P < 0.001) displayed higher reducing power activity than the standard compounds (ascorbic acid and butylated hydroxytoluene [BHT]). Total antioxidant capacity assay, measured by phosphomolybdate method, was 358.33 ± 5.77 μg butylated hydroxytoluene equivalents [BHTE]/mg extract. β-carotene-linoleate bleaching method affirmed the potency of EESTG because of its significantly (P < 0.001) higher anti-oxidant activity when compared with quercetin and BHT. Based on DPPH assay, EESTG displayed significantly (P < 0.001) higher activity than BHT, while the hydroxyl radical scavenging activities of BHT and quercetin significantly (P < 0.001) exceeded that of the extract, although EESTG still displayed a high level of activity obtained as 83.77% in comparison to 92.80% of the standard compounds. Conclusion: Findings from this study indicate the presence of promisingly potent phytoconstituents in EESTG that have the capability to act as antioxidants and free radical scavengers. PMID:25598635

  5. Method for determination of methyl tert-butyl ether and its degradation products in water

    USGS Publications Warehouse

    Church, C.D.; Isabelle, L.M.; Pankow, J.F.; Rose, D.L.; Tratnyek, P.G.

    1997-01-01

    An analytical method is described that can detect the major alkyl ether compounds that are used as gasoline oxygenates (methyl tert-butyl ether, MTBE; ethyl tert-butyl ether, ETBE; and tert-amyl methyl ether, TAME) and their most characteristic degradation products (tert-butyl alcohol, TBA; tert-butyl formate, TBF; and tert-amyl alcohol, TAA) in water at sub-ppb concentrations. The new method involves gas chromatography (GC) with direct aqueous injection (DAI) onto a polar column via a splitless injector, coupled with detection by mass spectrometry (MS). DAI-GC/MS gives excellent agreement with conventional purge-and-trap methods for MTBE over a wide range of environmentally relevant concentrations. The new method can also give simultaneous identification of polar compounds that might occur as degradation products of gasoline oxygenates, such as TBA, TBF, TAA, methyl acetate, and acetone. When the method was applied to effluent from a column microcosm prepared with core material from an urban site in New Jersey, conversion of MTBE to TBA was observed after a lag period of 35 days. However, to date, analyses of water samples from six field sites using the DAI-GC/MS method have not produced evidence for the expected products of in situ degradation of MTBE.An analytical method is described that can detect the major alkyl ether compounds that are used as gasoline oxygenates (methyl tert-butyl ether, MTBE; ethyl tert-butyl ether, ETBE; and tert-amyl methyl ether, TAME) and their most characteristic degradation products (tert-butyl alcohol, TBA; tert-butyl formate, TBF; and tert-amyl alcohol, TAA) in water at sub-ppb concentrations. The new method involves gas chromatography (GC) with direct aqueous injection (DAI) onto a polar column via a splitless injector, coupled with detection by mass spectrometry (MS). DAI-GC/MS gives excellent agreement with conventional purge-and-trap methods for MTBE over a wide range of environmentally relevant concentrations. The new method

  6. Splenic infarction after N-butyl-2-cyanoacrylate injection for gastric varices: why does it happen?

    PubMed

    Köksal, Aydin S; Kayaçetin, Ertuğrul; Torun, Serkan; Erkan, Vedat; Ökten, Riza S

    2013-10-01

    Recent guidelines and consensus reports recommend endoscopic injection therapy with N-butyl-2-cyanoacrylate as the first-line treatment for bleeding-isolated gastric varices and gastroesophageal varices types 1 and 2. Embolization is a rare but serious complication of cyanoacrylate injection, which may be fatal in some cases. Herein, we present a patient who developed splenic infarction after N-butyl-cyanoacrylate injection for gastroesophageal varices type 2 and discuss the potential reasons and tips to prevent the occurence of embolization. PMID:24105294

  7. Reaction of phenanthrene with tert-butylating agents under Friedel-Craft conditions

    SciTech Connect

    Pozdnyakovich, Yu.V.

    1988-10-20

    The alkylation of phenanthrene with tert-butyl alcohol in the presence of trifluoroacetic acid or with tert-butyl chloride, catalyzed by the TiCl/sub 4/, FeCl/sub 3/-CH/sub 3/NO/sub 2/, and AlCl/sub 3/-CH/sub 3/NO/sub 2/, leads to formation of 2- and 3-tert-butylphenanthrene and also 2,6-, 2,7-, and 3,6-di-tert-butylphenanthrene. The exhaustive alkylation of phenanthrene leads to the formation of the above-mentioned isomeric di-tert-butylphenanthrenes, the ratios of which depend on the nature of the catalyst.

  8. Irreversible H2-antagonism of the four isomeric butyl analogues of mifentidine.

    PubMed

    Bastiaans, H M; Donetti, A; Kramer, K; Bietti, G; Cereda, E; Dubini, D; Mondini, M; Bast, A; Timmerman, H

    1990-04-01

    It has been hypothesized that bidentate hydrogen bonding plays an important role in the interaction of imidazolylphenylformamidines with the H2-receptor. The present study, in which the degree of pseudo-irreversible H2-antagonism of the four isomeric butyl substituted mifentidine analogues was determined on the spontaneously beating right atrium of the male guinea-pig, lends further support to this hypothesis. In solution the EE/EZ ratio is different for the four isomeric butylated mifentidine analogues. The rank order of the percentage of E,E conformation, which favors a bidentate interaction, of the formamidine moiety parallels the rank order of pseudo-irreversible H2-antagonism. PMID:1973582

  9. Free radicals and activated oxygen.

    PubMed

    Famaey, J P

    1982-01-01

    Superoxide anion (0(-2)), hydrogen peroxide (H2O2) and hydroxyl radical (OH.) are products of the biological reduction of 0(2). They are very reactive and poorly tolerated within living systems and enzymes that catalytically scavenge these products have been evolved as defense mechanisms. These include superoxide dismutases (SOD), catalase and peroxidases. Large amounts of O-2 are produced by different enzymatic and non enzymatic biological processes. Large amounts of activated oxygens are produced by phagocytosing cells such as macrophages and polymorphonuclear cells. This production is associated with the bactericidal actions of these cells but it also largely contributes to exacerbate and sustain the inflammation where these cells congregate. The arachidonic acid pathway triggered by the inflammatory stimuli is also a source for these oxidizing radicals. The production of activated oxygens has been associated with the normal aging process but also with various toxic reactions (e.g. the toxicity of the herbicide paraquat, of the ionizing radiations, of certain antibiotics such as streptonigrin, etc. . . .). O-2 induces the depolymerization of hyaluronic acid which lends viscosity and lubricating properties to synovial fluids. SOD possess antiinflammatory properties and a bovine SOD, orgotein, has now been largely investigated by intramuscular and intraarticular injections in the treatment of rheumatic diseases. Various antiinflammatory compounds (e.g. the salicylates) are able either to inhibit the production of these oxygen radicals or to scavenge them which seems of importance for their antiinflammatory properties. Singlet oxygen, another activated oxygen, might also play a role in the inflammatory process. PMID:6295769

  10. Aromatic-radical oxidation chemistry

    SciTech Connect

    Glassman, I.; Brezinsky, K.

    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.

  11. Laser spectroscopy of hydrocarbon radicals

    SciTech Connect

    Chen, P.

    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.

  12. Iron and iron derived radicals

    SciTech Connect

    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 fastexclamation Think smallexclamation 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.

  13. 40 CFR 721.10326 - 2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... ester, polymer with butyl 2-propenoate, ethyl 2-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2... 2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2-propenoate (1:2), 2,2'-(1,2-diazenediyl)bis - and...

  14. Isotope effects on the metabolism and pulmonary toxicity of butylated hydroxytoluene in mice by deuteration of the 4-methyl group

    SciTech Connect

    Mizutani, T.; Yamamoto, K.; Tajima, K.

    1983-06-30

    A comparative test in mice for pulmonary toxicity between butylated hydroxytoluene (2,6-di-tert.-butyl-4-methylphenol, BHT) and 2,6-di-tert.-butyl-4-(alpha, alpha, alpha-2H3)methylphenol (BHT-d3) showed a significantly lower toxic potency of the latter. The rate of in vitro BHT metabolism to 2,6-di-tert.-butyl-4-methylene-2,5-cyclohexadienone (BHT-QM) was slowed by deuterating BHT in the 4-methyl group. On the other hand, the rate of in vitro metabolism to 2,6-di-tert.-butyl-4-hydroxy-4-methyl-2,5-cyclohexadienone (BHT-OH) was increased with the deuteration. A similar isotope effect of the deuterium substitution on the in vivo metabolic rates of BHT was observed. These observations support the concept that the lung damage caused by BHT is mediated by BHT-QM. The pulmonary toxicity of 2-tert.-butyl-4-ethylphenol (4-EP) and their deuterated analogs was also compared. 2-tert.-Butyl-4-(1,1-2H2)ethylphenol (4-EP-d2) showed a significantly lower toxic potency than 4-EP, whereas 2-tert.-butyl-4-(2,2,2-2H3)ethylphenol (4-EP-d3) showed a toxic potency comparable to that of 4-EP. This result is consistent with the hypothesis that a quinone methide metabolite is responsible for the onset of lung damage produced by 4-EP as well as BHT.

  15. A novel method to measure both the reductive and the radical scavenging activity in a linoleic acid model system.

    PubMed

    Lindenmeier, Michael; Burkon, Alexander; Somoza, Veronika

    2007-12-01

    The aim of this study was to develop a combined method for measuring the total antioxidant activity, the reductive and the radical scavenging activity. Linoleic acid was used as the substrate for an iron-initiated lipid peroxidation to measure the total antioxidant activity. In addition, methyl esters of linoleic acid hydroperoxides were used as substrates to measure the reductive antioxidant activity. The radical scavenging antioxidant activity was calculated by subtracting the reductive antioxidative activity from the total antioxidative activity. As representative examples, the antioxidants alpha-tocopherol, ascorbic acid, trans-resveratrol and L-glutathione as well as commonly used food additives such as 2(3)-tert-butyl-4-hydroxyanisole (BHA) and 2,6-bis(1,1-dimethylethyl)-4-methylphenol (BHT) were analyzed. The results for the novel antioxidation test showed that alpha-tocopherol, BHA and BHT are primarily acting as radical scavengers, whereas ascorbic acid and L-glutathione show a strong reductive capacity. As linoleic acid as well as its hydroperoxides both are present in foods and in the organism, the test presented here can be considered representative of radical reactions occurring in food matrixes and in vivo. Further experiments are required to document the comprehensive applicability in foods and in vivo. PMID:17680718

  16. Purification and antioxidant properties of bigeye tuna (Thunnus obesus) dark muscle peptide on free radical-mediated oxidative systems.

    PubMed

    Je, Jae-Young; Qian, Zhong-Ji; Lee, Sang-Hoon; Byun, Hee-Guk; Kim, Se-Kwon

    2008-12-01

    To produce bioactive peptides from by-products of fish processing, bigeye tuna dark muscle was hydrolyzed using various enzymes (alcalase, alpha-chymotrypsin, neutrase, papain, pepsin, and trypsin), and the hydrolysates were evaluated for antioxidant activity. Considering the results of degree of hydrolysis and antioxidant activities, peptic hydrolysate was used for further studies to identify a potent antioxidant peptide. Antioxidant peptide was purified using consecutive chromatographic methods and was identified as being H-Leu-Asn-Leu-Pro-Thr-Ala-Val-Tyr-Met-Val-Thr-OH (MW 1,222 Da) by quantitative time-of-flight electrospray ionization mass spectrometry. Purified antioxidant peptide from bigeye tuna dark muscle (APTDM) was investigated for its antioxidant activities using both free radical scavenging effects and polyunsaturated fatty acid (PUFA) peroxidation inhibitory activity. The results showed that APTDM effectively quenched with low 50% inhibitory concentration values compared to vitamin C as a positive control against four different free radicals: 1,1-diphenyl-2-picrylhydrazyl, hydroxyl, superoxide, and alkyl radical. APTDM also inhibited PUFA peroxidation in a linoleic acid emulsion system, and the activity was similar to that of alpha-tocopherol. We further investigated its antioxidant activities on cellular systems, and the results showed that APTDM significantly scavenged cellular radicals and enhanced the viability of tert-butyl hydroperoxide-induced cytotoxicity. These results indicate that APTDM or a peptide fraction containing APTDM would be a beneficial ingredient for functional food and/or pharmaceuticals. PMID:19053853

  17. ESR spin trapping study of the effect of oxidative stress and dietary Zn deficiency on free radical production in vivo

    SciTech Connect

    Xu, Z.; Chen, G.; Bray, T.M. )

    1991-03-15

    The objective of this study is to examine if free radicals can be trapped in vivo in dietary Zn deficient rats using ESR spin trapping techniques. The ability of Zn deficient rats to cope with oxidative stress is also assessed. {alpha}-Phenyl-N-t-butyl-nitrone (PBN), a spin trap, was i.p injected at a dose of 75 mg or 150 mg/kg body weight. The tissue distribution and metabolism of PBN in Zn deficient, pair-fed and control rats were compared. ESR signals in liver and lung were used as a measure of free radicals generated in vivo. When the rats were challenged with free radical generating agents, CCl{sub 4}, or FeNTA, the intensity of ESR signal recorded from the Zn deficient rats was about 50% and 30% of its pair-fed and ad libitum control, respectively. Under other oxidative stress, such as exposure to ethanol and hyperoxia, there was a higher production of free radicals in the Zn deficient rats compared to its control. These results suggest that dietary Zn deficiency may either increase the susceptibility or reduce the defense ability of the animal to increased oxidative stress.

  18. 3-Pyridinols and 5-pyrimidinols: Tailor-made for use in synergistic radical-trapping co-antioxidant systems

    PubMed Central

    Bartolomei, Daniele; Amorati, Riccardo; Haidasz, Evan; Hanthorn, Jason J; Nara, Susheel J; Brinkhorst, Johan

    2013-01-01

    Summary The incorporation of nitrogen atoms into the aromatic ring of phenolic compounds has enabled the development of some of the most potent radical-trapping antioxidants ever reported. These compounds, 3-pyridinols and 5-pyrimidinols, have stronger O–H bonds than equivalently substituted phenols, but possess similar reactivities toward autoxidation chain-carrying peroxyl radicals. These attributes suggest that 3-pyridinols and 5-pyrimidinols will be particularly effectiveco-antioxidants when used in combination with more common, but less reactive, phenolic antioxidants such as 2,6-di-tert-butyl-4-methylphenol (BHT), which we demonstrate herein. The antioxidants function in a synergistic manner to inhibit autoxidation; taking advantage of the higher reactivity of the 3-pyridinols/5-pyrimidinols to trap peroxyl radicals and using the less reactive phenols to regenerate them from their corresponding aryloxyl radicals. The present investigations were carried out in chlorobenzene and acetonitrile in order to provide some insight into the medium dependence of the synergism and the results, considered with some from our earlier work, prompt a revision of the H-bonding basicity value of acetonitrile to β2 H of 0.39. Overall, the thermodynamic and kinetic data presented here enable the design of co-antioxidant systems comprising lower loadings of the more expensive 3-pyridinol/5-pyrimidinol antioxidants and higher loadings of the less expensive phenolic antioxidants, but which are equally efficacious as the 3-pyridinol/5-pyrimidinol antioxidants alone at higher loadings. PMID:24367442

  19. Highly sensitive free radical detection by nitrone-functionalized gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Du, Libo; Huang, Saipeng; Zhuang, Qianfen; Jia, Hongying; Rockenbauer, Antal; Liu, Yangping; Liu, Ke Jian; Liu, Yang

    2014-01-01

    The detection of free radicals and related species has attracted significant attention in recent years because of their critical roles in physiological and pathological processes. Among the methods for the detection of free radicals, electron spin resonance (ESR) coupled with the use of the spin trapping technique has been an effective approach for characterization and quantification of these species due to its high specificity. However, its application in biological systems, especially in in vivo systems, has been greatly limited partially due to the low reaction rate between the currently available spin traps with biological radicals. To overcome this drawback, we herein report the first example of nitrone functionalized gold nanoparticles (Au@EMPO) as highly efficient spin traps in which the thiolated EMPO (2-(ethoxycarbonyl)-2-methyl-3,4-dihydro-2H-pyrrole 1-oxide) derivative was self-assembled on gold nanoparticles. Kinetic studies showed that Au@EMPO has a 137-fold higher reaction rate constant with &z.rad;OH than PBN (N-tert-butyl-α-phenylnitrone). Owing to the high rate of trapping &z.rad;OH by Au@EMPO as well as the high stability of the resulting spin adduct (t1/2 ~ 56 min), Au@EMPO affords 124-fold higher sensitivity for &z.rad;OH than EMPO. Thus, this new nanospin trap shows great potential in trapping the important radicals such as &z.rad;OH in various biological systems and provides a novel strategy to design spin traps with much improved properties.The detection of free radicals and related species has attracted significant attention in recent years because of their critical roles in physiological and pathological processes. Among the methods for the detection of free radicals, electron spin resonance (ESR) coupled with the use of the spin trapping technique has been an effective approach for characterization and quantification of these species due to its high specificity. However, its application in biological systems, especially in in vivo systems

  20. alpha-Phenyl-n-tert-butyl-nitrone attenuates hypoxic-ischemic white matter injury in the neonatal rat brain.

    PubMed

    Lin, Shuying; Rhodes, Philip G; Lei, Manping; Zhang, Feng; Cai, Zhengwei

    2004-05-01

    White matter of the neonatal brain is highly sensitive to hypoxic-ischemic insult. The susceptibility of premature oligodendrocytes (OLs) to free radicals (FRs) produced during hypoxia-ischemia (HI) has been proposed as one of the mechanisms involved. To test this hypothesis, and to further investigate if the FR scavenger alpha-phenyl-N-tert-butyl-nitrone (PBN) attenuates hypoxic-ischemic white matter damage (WMD), postnatal day 4 (P4) SD rats were subjected to bilateral common carotid artery ligation (BCAL), followed by 8% oxygen exposure for 20 min. Pathological changes were evaluated on P6 and P9, 2 and 5 days after the HI insult. HI caused severe WMD including rarefaction, necrosis and cavity formation in the corpus callosum, external and internal capsule areas. OL injury was evidenced by degeneration of O4 positive OLs on P6. Disrupted myelination was verified by decreased immunostaining of myelin basic protein (MBP) on P9. Axonal injury was demonstrated by increased amyloid precursor protein (APP) immunostaining on both P6 and P9. Two lipid peroxidation end products, malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), showed a one-fold elevation within 1-24 h following HI. 4-HNE immunostaining was found to specifically localize in the white matter area. Furthermore, pyknotic O4+ OLs were double-labeled with 4-HNE. These findings suggest that FRs are involved in the pathogenesis of neonatal WMD. PBN (100 mg/kg, i.p.) treatment alleviated the pathological changes of WMD following HI. It improved the survival of O4 positive OLs, attenuated hypomyelination and reduced axonal damage. PBN treatment also decreased the brain concentration of MDA/4-HNE and positive 4-HNE staining in the white matter area. These findings indicate that in the current WMD model, PBN protects both OLs and axons, the two main components in the white matter, from neonatal HI insult. FR scavenging appears to be the primary mechanism underlying its neuroprotective effect. PMID:15064144

  1. Effects of endocrine disruptor di-n-butyl phthalate on the growth of Bok choy (Brassica rapa subsp. chinensis).

    PubMed

    Liao, Chien-Sen; Yen, Jui-Hung; Wang, Yei-Shung

    2006-12-01

    The effects of the endocrine disrupter, di-n-butyl phthalate (DBP), on the growth of leaf vegetable Bok choy (Brassica rapa subsp. chinensis, white stem Bok choy) were investigated. The results showed that leaves of Bok choy became white in color with the occurrence of chlorosis and necrosis upon treating with 30 mg l(-1) DBP for 42 days. Transmission electron microscopic images revealed that changes in the chloroplast structures accompanied the chlorosis. In addition, a decrease in biomass and chlorophyll, and accumulation of DBP, were found in DBP-treated Bok choy. The growth and morphology of Bok choy showed a significant dose-response relationship upon treatment with DBP in a hydroponic culture medium. The proteome of the leaf tissue was analyzed using two-dimensional gel electrophoresis (2-DE) and mass spectrometry (MS). Six protein spots were identified in 2-DE that showed reproducible differences in expression between the normal control and the DBP-treated sample. Based on proteome level studies two protein spots increased and were identified as superoxide dismutase (SOD) and peroxidase 21 precursor. These proteins are believed to increase in expression in response to free radical exposure as a detoxification mechanism. The other four protein spots that disappeared on treatment with DBP were identified as heat shock cognate protein 80, protein disulfide isomerase precursor, apocytochrome f precursor, and RNA polymerase beta subunit. The first two play an important role in polypeptide folding, the third is associated with electron transport, and the last has a critical function in DNA transcription. This study indicated that DBP affects the proteome formation as well as the physiology and the morphology of Bok choy during growth. The decrease in those four proteins might be related to the growth and development of a plant. PMID:16824579

  2. N-tert-butyl-alpha-phenylnitrone protects against 3,4-methylenedioxymethamphetamine-induced depletion of serotonin in rats.

    PubMed

    Yeh, S Y

    1999-03-01

    The present study examined the effect of N-tert-butyl-alpha-phenylnitrone (PBN) on 3,4-methylenedioxmathamphetamine (MDMA)-induced depletion of serotonin in the CNS. Rats were treated with two concurrent injections of MDMA (20 mg/kg, s.c.), PBN (50-400 mg/kg dissolved in ethanol, 50 mg/ml of 25% ethanol, i.p.), saline or 25% ethanol, alone or in combination, 6 h apart, and sacrificed 5 days later. Rectal temperature was measured prior to and hourly following the drug injection for 5 h. Monoamine levels in the tissue were measured by HPLC. Density of the 5-HT transporters was assayed by [3H]paroxetine binding. Rectal temperature of rats increased after MDMA, decreased after PBN, ethanol, PBN plus ethanol, and MDMA plus ethanol, and was not significantly altered after MDMA plus PBN. Levels of 5-HT and 5-HIAA in the frontal cortex, hippocampus, striatum, and brain stem of rats decreased significantly after MDMA or MDMA plus ethanol, but not after MDMA plus PBN, PBN plus ethanol (PBN dissolved in ethanol), or ethanol as compared to the saline controls. Levels of 5-HT and 5-HIAA in the brain tissues of rats treated with MDMA plus PBN were elevated as compared to those treated with MDMA plus saline. Similar results were observed in the density of 5-HT transporters in the frontal cortex and hippocampus. These results indicate that scavenging of free radicals of MDMA metabolites or reactive oxygen species by PBN and with lowering of body temperature protected against MDMA-induced depletion of serotonin transmitter. PMID:10029234

  3. Graphene oxide as a radical initiator: Free radical and controlled radical polymerization of sodium 4-vinylbenzenesulfonate with graphene oxide

    DOE PAGESBeta

    Voylov, Dmitry N.; Saito, Tomonori; Lokitz, Bradley S.; Uhrig, David; Wang, Yangyang; Agapov, Alexander L.; Holt, Adam P.; Bocharova, Vera; Kisliuk, Alexander; Sokolov, Alexei P.

    2016-01-19

    The free radical and controlled radical polymerization of sodium 4-vinylbenzenesulfonate using graphene oxide as a radical initiator was studied. This work demonstrates that graphene oxide can initiate radical polymerization in an aqueous solution without any additional initiator. Poly(sodium 4-vinylbenzenesulfonate) obtained via reversible addition fragmentation chain transfer polymerization had a controlled molecular weight with a very narrow polydispersity ranging between 1.01 and 1.03. Furthermore, the reduction process of graphene oxide as well as the resulting composite material properties were analyzed in detail.

  4. Tris(Cyclopentadienyl)Uranium-t-Butyl: Synthesis, reactions, and mechanisms

    SciTech Connect

    Weydert, M.

    1993-04-01

    Compounds (RC{sub 5}H{sub 4}){sub 3}U(t-Bu) were prepared for R = H, Me, Et. Their decomposition products in aromatic solvents are consistent with a radical decomposition pathway induced by solvent-assisted U-C bond homolysis. NMR was used to study the reactions of (RC{sub 5}H{sub 4}){sub 3}UCl with t-BuLi (R = t-Bu, Me{sub 3}Si). Reactions of (MeC{sub 5}H{sub 4}){sub 3}U(t-Bu) with Lewis bases and fluorocarbons were studied. Analogous reaction chemistry between (RC{sub 5}H{sub 4}){sub 3}ThX systems and t-BuLi was also studied, and reactivity differences between U and Th are discussed. Synthesis of sterically crowded (RC{sub 5}H{sub 4}){sub 4}U compounds is next considered. Reaction of the trivalent (RC{sub 5}H{sub 4}){sub 3}U with (RC{sub 5}H{sub 4}){sub 2}Hg results in formation of (RC{sub 5}H{sub 4}){sub 4}U. Steric congestion, cyclopentadienyl ligand exchange, and electron transfer are discussed. (DLC)

  5. Tris(Cyclopentadienyl)Uranium-t-Butyl: Synthesis, reactions, and mechanisms

    SciTech Connect

    Weydert, M.

    1993-04-01

    Compounds (RC[sub 5]H[sub 4])[sub 3]U(t-Bu) were prepared for R = H, Me, Et. Their decomposition products in aromatic solvents are consistent with a radical decomposition pathway induced by solvent-assisted U-C bond homolysis. NMR was used to study the reactions of (RC[sub 5]H[sub 4])[sub 3]UCl with t-BuLi (R = t-Bu, Me[sub 3]Si). Reactions of (MeC[sub 5]H[sub 4])[sub 3]U(t-Bu) with Lewis bases and fluorocarbons were studied. Analogous reaction chemistry between (RC[sub 5]H[sub 4])[sub 3]ThX systems and t-BuLi was also studied, and reactivity differences between U and Th are discussed. Synthesis of sterically crowded (RC[sub 5]H[sub 4])[sub 4]U compounds is next considered. Reaction of the trivalent (RC[sub 5]H[sub 4])[sub 3]U with (RC[sub 5]H[sub 4])[sub 2]Hg results in formation of (RC[sub 5]H[sub 4])[sub 4]U. Steric congestion, cyclopentadienyl ligand exchange, and electron transfer are discussed. (DLC)

  6. Radical formation and radiation damage in adamantane

    SciTech Connect

    Lloyd, R.V.; DiGregorio, S.; DiMauro, L.; Wood, D.E.

    1980-10-30

    Unequivocal samples of the 1-adamantyl (1-Ad) and 2-Ad radicals have been prepared in a matrix of adamantane (Ad) by the simultaneous deposition of atomic sodium, 1- or 2-bromoadamantane, and adamantance at 77 K. The EPR spectrum of the 1-Ad radical contrary to previous reports has a clearly resolved hyperfine structure that can be analyzed in terms of the solution parameters of Krusic et al., and the spectrum of the 2-Ad radical is identical with that previously reported by Ferrell et al. It is also shown that conditions of purification and irradiation can greatly affect the spectra obtained upon X irradiation of Ad itself. Depending upon conditions, alicyclic radicals that are primary products of ring-opening reactions or benzylic-type radicals that are probably secondary reaction products can also be obtained in addition to 1-Ad and 2-Ad radicals.

  7. [Free radicals in immunology and infectious diseases].

    PubMed

    Racek, J; Holecek, V; Sedlácek, D; Panzner, P

    2001-04-01

    Free radicals contribute significantly in modification of immune processes and inflammatory reactions. They are produced by activated phagocytes which use them for killing microorganisms. Free radicals facilitate production of cytokines, which are important as modifiers of inflammatory reactions. Formation of free radicals is influenced by antioxidants which can thus modify the intensity of inflammatory reaction and immune response. The authors describe in detail the contribution of free radicals in etiology and pathogenesis of autoimmune diseases including rheumatoid arthritis, multiple sclerosis or amyotrophic lateral sclerosis. The role of free radicals and modifying influence of antioxidants in viral, bacterial, parasitic and mycotic diseases is described in the second part of the review. Finally, influence of free radicals and antioxidants on immunity changes in patients with malignant tumours, during aging and physical exercise is discussed. PMID:11329733

  8. Electron spin resonance spectra of nitroxyl radicals

    NASA Astrophysics Data System (ADS)

    Botek, Edith; Zarycz, Natalia; Champagne, Benoît; Sciannaméa, Valérie; Detrembleur, Christophe

    2012-12-01

    Hyperfine coupling constants (HFCCs) of nitroxyl radicals were calculated using density functional theory (DFT) to address the structure of nitroxide intermediates in controlled radical polymerization. In a preliminary step, the reliability of different theoretical methods has been substantiated by comparing calculated HFCCs to experimental data for a set of acyclic and cyclic alkylnitroxyl radicals. In a second step this tested approach was applied to support experimental evidence of several nitroxide-mediated polymerization (NMP) reactions.

  9. Quantitative determination of atmospheric hydroperoxyl radical

    DOEpatents

    Springston, Stephen R.; Lloyd, Judith; Zheng, Jun

    2007-10-23

    A method for the quantitative determination of atmospheric hydroperoxyl radical comprising: (a) contacting a liquid phase atmospheric sample with a chemiluminescent compound which luminesces on contact with hydroperoxyl radical; (b) determining luminescence intensity from the liquid phase atmospheric sample; and (c) comparing said luminescence intensity from the liquid phase atmospheric sample to a standard luminescence intensity for hydroperoxyl radical. An apparatus for automating the method is also included.

  10. Free-radical chemistry of sulfite

    SciTech Connect

    Neta, P.; Huie, R.E.

    1985-12-01

    The free-radical chemistry of sulfite oxidation is reviewed. Chemical transformations of organic and biological molecules induced by sulfite oxidation are summarized. The kinetics of the free-radical oxidations of sulfite are discussed, as are the kinetics of the reactions of the sulfite-derived radicals SO/sub 3/ and the peroxy derivative SO/sub 5/ with organic compounds. 98 references.

  11. Energetics of mechanical destruction of middle radicals

    NASA Astrophysics Data System (ADS)

    Kvachadze, N. G.; Tomashevskii, E. E.; Zhizhenkov, V. V.

    2015-11-01

    The breaking strain of a model fragment of a middle radical in a rigid polymer matrix has been calculated. The force and energy characteristics of the destruction of the radical and the formation of double bonds have been estimated. The dissociation energy and the strength of Cβ-Cγ bonds for trans- and gaucheconformers of radicals have been determined. It has been established that the probability of breaking of the β bonds essentially depends of the conformation structure of the macroradicals.

  12. 40 CFR 721.10193 - 1-Butanaminium, N-(3-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts. 721.10193 Section 721.10193 Protection of...-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts. (a) Chemical substance and...-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts (PMN P-06-263, Chemical B; CAS...

  13. 40 CFR 721.10193 - 1-Butanaminium, N-(3-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts. 721.10193 Section 721.10193 Protection of...-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts. (a) Chemical substance and...-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts (PMN P-06-263, Chemical B; CAS...

  14. IRIS Toxicological Review of Ethyl Tertiary Butyl Ether (Etbe) (Public Comment Draft)

    EPA Science Inventory

    In September 2016, the U.S. Environmental Protection Agency's (USEPA) released the draft Integrated Risk Information System (IRIS) Toxicological Review of Ethyl Tertiary Butyl Ether (ETBE). Consistent with the 2013 IRIS Enhancements, draft IRIS assessments are released prior to e...

  15. Draft Genome Sequence of Sphingobium yanoikuyae TJ, a Halotolerant Di-n-Butyl-Phthalate-Degrading Bacterium

    PubMed Central

    Jin, Decai; Zhu, Ying; Wang, Xinxin; Kong, Xiao; Liu, Huijun; Wang, Yafeng

    2016-01-01

    Sphingobium yanoikuyae TJ is a halotolerant di-n-butyl-phthalate-degrading bacterium, isolated from the Haihe estuary in Bohai Bay, Tianjin, China. Here, we report the 5.1-Mb draft genome sequence of this strain, which will provide insights into the diversity of Sphingobium spp. and the mechanism of phthalate ester degradation in the estuary. PMID:27313307

  16. AN EVALUATION OF THE HUMAN CARCINOGENIC POTENTIAL OF ETHYLENE GLYCOL BUTYL ETHER: INTERIM FINAL POSITION PAPER

    EPA Science Inventory

    In order to determine the merit of a petition to remove ethylene glycol ether (EGBE) from the Agency's Hazardous Air Pollutant (HAP) list, EPA has developed an interim final position paper, An Evaluation of the Human Carcinogenic Potential of Ethylene Glycol Butyl Ether, t...

  17. N-Butyl 2-Cyanoacrylate Embolization of Spinal Dural Arteriovenous Fistula

    PubMed Central

    Kwon, B.J.; Kim, T.-K.; Seo, S.I.; Kyung, J.B.; Seol, H.Y.; Han, M.H.

    2005-01-01

    Summary We report an unusual case of spinal dural arteriovenous fistula (SDAVF) presenting with subarachnoid haemorrhage (SAH). Cure was achieved with endovascular treatment with n-butyl 2-cyanoacrylate (NBCA). A review of the literature revealed five cases of cervical SDAVF that presented with SAH. None of these cases were treated with NBCA. PMID:20584439

  18. Energetic Materials Center Report--Small-Scale Safety and Thermal Testing Evaluation of Butyl Nitrate

    SciTech Connect

    Hsu, Peter C.; Reynolds, John G.

    2013-04-26

    Butyl Nitrate (BN) was examined by Small-Scale Safety and Thermal (SSST) Testing techniques to determine its sensitivity to impact, friction, spark and thermal exposure simulating handling and storage conditions. Under the conditions tested, the BN exhibits thermal sensitivity above 150 °C, and does not exhibit sensitive to impact, friction or spark.

  19. 2-Butyl-4-chloroimidazole based substituted piperazine-thiosemicarbazone hybrids as potent inhibitors of Mycobacterium tuberculosis.

    PubMed

    Jallapally, Anvesh; Addla, Dinesh; Yogeeswari, Perumal; Sriram, Dharmarajan; Kantevari, Srinivas

    2014-12-01

    Here a series of 2-butyl-4-chloroimidazole based substituted piperazine-thiosemicarbazone hybrids were designed by combining three different pharmacophoric fragments in single molecular architecture. 2-Butyl-4-chloro-1-(3-(4-substituted)piperazin-1-yl)propyl)-1H-imidazole-5-carbaldehydes (4a-p) prepared by reacting carboxaldehyde 2 with N-alkyl piperazines 3a-p which were condensed with thiosemicarbazine to give desired compounds 5a-p in very good yields. Among all sixteen compounds screened for in vitro antimycobacterial activity against Mycobacterium tuberculosis H37Rv (MTB), two compounds (E)-2-((2-butyl-4-chloro-1-(3-(4-(o-tolyl) piperazin-1-yl)propyl)-1H-imidazol-5-yl)methylene)hydrazinecarbothioamide 5e and (E)-2-((2-butyl-4-chloro-1-(3-(4-(2-methoxyphenyl)piperazin-1-yl)propyl)-1H-imidazol-5-yl)methylene) hydrazine carbothioamide 5f were found to be the most potent antitubercular agents (MIC: 3.13 μg/mL) with low toxicity profile. PMID:25451998

  20. Characterization of cellulose II nanoparticles regenerated from ionic liquid, 1-butyl-3-methylimidazolium chloride

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Regenerated cellulose nanoparticles (RCNs) including both elongated fiber and spherical structures were prepared from microcrystalline cellulose (MCC)and cotton using 1-butyl-3-methylimidazolium chloride followed by high-pressure homogenization. The crystalline structure of RCNs was cellulose II in ...

  1. IRIS Toxicological Review of Ethyl Tertiary Butyl Ether (Etbe) (Interagency Science Consultation Draft)

    EPA Science Inventory

    In September 2016, EPA released the draft IRIS Toxicological Review of Ethyl Tertiary Butyl Ether (ETBE) for public comment and discussion. The draft assessment was reviewed internally by EPA and by other federal agencies and White House Offices before public release. Consistent ...

  2. ATTENUATION OF METHYL TERT-BUTYL ETHER IN WATER USING SUNLIGHT AND A PHOTOCATALYST

    EPA Science Inventory

    The use of methyl tert-butyl ether (MTBE) as a gasoline additive has resulted in increasing pollution of ground water. Most of the conventional treatment technologies are inefficient or costly when the initial concentration of MTBE is low (<200 ug/L). In order to find an eco-frie...

  3. MONITORED NATURAL ATTENUATION OF TERTIARY BUTYL ALCOHOL (TBA) IN GROUND WATER AT GASOLINE SPILL SITES

    EPA Science Inventory

    The state agencies that implement the Underground Storage Tank program rely heavily on Monitored Natural Attenuation (MNA) to clean up contaminants such as benzene and methyl tertiary butyl ether (MTBE) at gasoline spill sites. This is possible because the contaminants are biolo...

  4. AN EVALUATION OF THE HUMAN CARCINOGENIC POTENTIAL OF ETHYLENE GLYCOL BUTYL ETHER (EGBE)

    EPA Science Inventory

    Background

    The position paper, An Evaluation of the Human Carcinogenic Potential of Ethylene Glycol Butyl Ether, was developed in support of the Agency's evaluation of a petition from the...

  5. IRIS Toxicological Review of Ethylene Glycol Mono-Butyl Ether (EGBE) (Interagency Science Discussion Draft)

    EPA Science Inventory

    EPA is releasing the draft report, Toxicological Review for Ethylene Glycol Mono-Butyl Ether , that was distributed to Federal agencies and White House Offices for comment during the Science Discussion step of the IRIS Assessme...

  6. Production of butyl acetate ester by lipase from novel strain of Rhizopus oryzae.

    PubMed

    Ben Salah, Riadh; Ghamghui, Hanen; Miled, Nabil; Mejdoub, Hafedh; Gargouri, Youssef

    2007-04-01

    A new lipase preparation from Rhizopus oryzae was used to catalyze the esterification reaction between acetic acid and butanol to produce butyl acetate ester (pineapple flavor). This flavor compound can be used in food, cosmetic and pharmaceutical industries. Only 3% of butyl acetate was obtained when free lipase was used in the synthesis containing only the substrates. In contrast, the conversion yield reached 25% when immobilized lipase was used under the same conditions. The synthesis of butyl acetate catalyzed by immobilized lipase in nonconventional media was optimized. A maximum conversion yield of 60% in a solvent-free system was obtained under the following conditions: amount of immobilized lipase, 500 IU; amount of initially added water, 45%; acetic acid/butanol molar ratio, 1:1; and in incubation temperature, 37 degrees C. Immobilized lipase could be repeatedly used for three cycles without a decrease in synthesis activity. The production of butyl acetate esters by immobilized R. oryzae lipase was also studied in the presence of organic solvents. Compared with a solvent-free system, the synthesis activity was improved in the presence of heptane and hexane with conversion yields of 80% and 76%, respectively. However, solvent-free systems tend to purify more easily the products without any toxicity and inflammability problems. PMID:17502279

  7. PHYSIOLOGICALLY BASED PHARMACOKINETIC MODEL FOR HUMAN EXPOSURES TO METHYL TERTIARY-BUTYL ETHER

    EPA Science Inventory

    Humans can be exposed by inhalation, ingestion, or dermal absorption to methyl tertiary-butyl ether (MTBE), an oxygenated fuel additive, from contaminated water sources. The purpose of this research was to develop a physiologically based pharmacokinetic model describing in human...

  8. OCCURRENCE OF METYL TERT-BUTYL ETHER (MTBE) AT FIVE MARINAS IN LAKE TEXOMA

    EPA Science Inventory



    Occurrence of methyl tert-butyl ether (MTBE) in five marinas was monitored between June 1999 and November 2000 in Lake Texoma located on the border of Oklahoma and Texas. MTBE is a commonly used gasoline additive and a suspected carcinogen. Lake water was collected at loc...

  9. A direct and sustainable synthesis of tertiary butyl esters enabled by flow microreactors.

    PubMed

    Degennaro, Leonardo; Maggiulli, Daniela; Carlucci, Claudia; Fanelli, Flavio; Romanazzi, Giuseppe; Luisi, Renzo

    2016-08-01

    Tertiary butyl esters find large applications in synthetic organic chemistry. A straightforward method for the direct introduction of the tert-butoxycarbonyl group into a variety of organic compounds has been developed using flow microreactor systems. The resultant flow process was more efficient, versatile and sustainable compared to the batch. PMID:27383138

  10. BIODEGRADATION OF METHYL TERT-BUTYL ETHER USING AN INNOVATIVE BIOMASS CONCENTRATOR REACTOR

    EPA Science Inventory

    The aerobic biodegradation of methyl tert-butyl ether (MTBE) was investigated using a pilot-scale Biomass Concentrator Reactor (BCR). The reactor was operated for a year at a flow rate of 2500 L/d of Cincinnati dechlorinated tap water and an influent MTBE concentration o...

  11. ATTENUATION OF METHYL TERT-BUTYL ETHER IN WATER USING SUNLIGHT AND A PHOTOCATALYST: JOURNAL ARTICLE

    EPA Science Inventory

    NRMRL-CIN-1535 Sahle-Demessie*, E., Enriquez*, J., and Gupta, G. Attenuation of Methyl tert-Butyl Ether in Water using Sunlight and a Photocatalyst. Water Environment Research (Virginia: Water Environment Federation) 74 (2):122-130 (2002). EPA/600/J-02/236. 07/19/2001 The use o...

  12. STRUCTURES AND BINDING ENERGIES OF METHYL TERT-BUTYL ETHER-WATER COMPLEXES

    EPA Science Inventory

    Methyl tert-butyl ether (MTBE) is a well-known environmental contaminant owing to its high solubility in water. Since the early 1990s, MTBE has been added to gasoline to improve air quality in some metropolitan areas of the United States. Improved air quality was, however, achiev...

  13. Enhanced diisobutene production in the presence of methyl tertiary butyl ether

    DOEpatents

    Smith, L.A. Jr.

    1983-03-01

    In the liquid phase reaction of isobutene in the presence of resin cation exchange resins with itself in a C[sub 4] hydrocarbon stream to form dimers, the formation of higher polymers, oligomers, and co-dimer by-products is suppressed by the presence of 0.0001 to 1 mole per mole of isobutene of methyl tertiary butyl ether. 1 fig.

  14. 76 FR 46796 - Butylate; Registration Review Proposed Decision; Notice of Availability

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-03

    ... Register on July 28, 2010 (75 FR 44240; FRL-8835-2). For the remaining butylate product registrations... published in the Federal Register on March 23, 2011 (76 FR 16147, FRL-8867-8). Due to the cancellation... decision. Registration review is EPA's periodic review of pesticide registrations to ensure that...

  15. INHALATION EXPOSURE TO METHYL TERT-BUTYL ETHER (MTBE) AND DIBROMOCHLOROMETHANE (DBCM) USING CONTINUOUS BREATH ANALYSIS

    EPA Science Inventory

    The oxygenate methyl tert-butyl ether (MTBE) has been added to gasoline to help meet national ambient air quality standards in those parts of the U.S. that are non-compliant for carbon monoxide. Although MTBE has provided important health benefits in terms of reduced haza...

  16. Aerobic mineralization of MTBE and tert-butyl alcohol by stream-bed sediment microorganisms

    USGS Publications Warehouse

    Bradley, P.M.; Landmeyer, J.E.; Chapelle, F.H.

    1999-01-01

    Microorganisms indigenous to the stream-bed sediments at two gasoline- contaminated groundwater sites demonstrated significant mineralization of the fuel oxygenates, methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA). Up to 73% of [U-14C]-MTBE and 84% of [U-14C]-TBA were degraded to 14CO2 under mixed aerobic/anaerobic conditions. No significant mineralization was observed under strictly anaerobic conditions. The results indicate that, under the mixed aerobic/anaerobic conditions characteristic of stream-bed sediments, microbial processes may provide a significant environmental sink for MTBE and TBA delivered to surface water bodies by contaminated groundwater or by other sources.Microorganisms indigenous to the stream-bed sediments at two gasoline-contaminated groundwater sites demonstrated significant mineralization of the fuel oxygenates, methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA). Up to 73% of [U-14C]-MTBE and 84% of [U-14C]-TBA were degraded to 14CO2 under mixed aerobic/anaerobic conditions. No significant mineralization was observed under strictly anaerobic conditions. The results indicate that, under the mixed aerobic/anaerobic conditions characteristic of stream-bed sediments, microbial processes may provide a significant environmental sink for MTBE and TBA delivered to surface water bodies by contaminated groundwater or by other sources.

  17. TREATMENT OF METHYL TERT-BUTYL ETHER CONTAMINATED WATER USING PHOTOCATALYSIS

    EPA Science Inventory

    The feasibility of photo-oxidation treatment of methyl tert-butyl ether (MTBE) in water was investigated in three ways, 1) using a slurry falling film photo-reactor, 2) a batch solar reactor system, and 3) a combination of air-stripping and gas phase photooxidation system. MTBE-c...

  18. PHOTOCATALYTIC OXIDATION OF METHYL-TERT-BUTYL ETHER FOR DRINKING WATER TREATMENT

    EPA Science Inventory

    The photo-oxidation of methyl tert-butyl ether (MTBE) in water was investigated to determine the feasibility of using photocatalysis for the treatment of MTBE-contaminated drinking water. The feasibility assessment was conducted using slurries of titanium dioxide in both a photo-...

  19. DERMAL, ORAL, AND INHALATION PHARMACOKINETICS OF METHYL TERTIARY BUTYL ETHER (MTBE) IN HUMAN VOLUNTEERS

    EPA Science Inventory

    Methyl tertiary butyl ether (MTBE), a gasoline additive, used to increase octane and reduce carbon monoxide emissions and ozone precursors has contaminated drinking water leading to exposure by oral, inhalation, and dermal routes. To determine its dermal, oral, and inhalation ki...

  20. DERMAL, ORAL AND INHALATION PHARMACOKINETICS OF METHYL TERTIARY-BUTYL ETHER (MTBE) IN HUMAN VOLUNTEERS

    EPA Science Inventory


    Methyl tertiary butyl ether (MTBE), a gasoline additive used to increase octane and reduce carbon monoxide emissions and ozone precursors, has contaminated drinking water and can lead to exposure by oral, inhalation, and dermal routes. To determine its dermal, oral, and inhal...

  1. REFINED PBPK MODEL OF AGGREGATE EXPOSURE TO METHYL TERTIARY-BUTYL ETHER

    EPA Science Inventory

    Aggregate (multiple pathway) exposures to methyl tertiary-butyl ether (MTBE) in air and water occur via dermal, inhalation, and oral routes. Previously, physiologically-based pharmacokinetic (PBPK) models have been used to quantify the kinetic behavior of MTBE and its primary met...

  2. IRIS Toxicological Review of Ethyl Tertiary Butyl Ether (Etbe) (External Review Draft, 2009)

    EPA Science Inventory

    EPA is conducting a peer review and public comment of the scientific basis supporting the human health hazard and dose-response assessment of ethyl tertiary butyl ether (ETBE) that when finalized will appear on the Integrated Risk Information System (IRIS) database.

  3. IRIS Toxicological Review of Tert-Butyl Alcohol (Tert-Butanol) (Public Comment Draft)

    EPA Science Inventory

    EPA is developing an Integrated Risk Information System (IRIS) assessment of tert-butyl Alcohol (tert-butanol) and has released the public comment draft assessment for public comment and external peer review. When final, the assessment will appear on the IRIS databa...

  4. BIODEGRADATION OF METHYL TERT-BUTYL ETHER AND BTEX AT VARYING HYDRAULIC RETENTION TIMES

    EPA Science Inventory

    The feasibility of biologically degrading methyl tert-butyl ether (MTBE) contaminated groundwater is dependent on the ability to degrade MTBE and its byproducts in the presence of other gasoline contaminants. This study investigates a mixed culture degrading both MTBE and benzene...

  5. IRIS Toxicological Review of Tert-Butyl Alcohol (Tert-Butanol) (Interagency Science Consultation Draft)

    EPA Science Inventory

    On April 29, 2016, the Toxicological Review of tert-Butyl Alcohol (tert-Butanol) (Public Comment Draft) was released for public comment. The draft Toxicological Review and charge were reviewed internally by EPA and by other federal agencies and the Executive Office ...

  6. IRIS Toxicological Review of Ethyl Tertiary Butyl Ether (Etbe) (External Review Draft)

    EPA Science Inventory

    EPA is conducting a peer review and public comment of the scientific basis supporting the human health hazard and dose-response assessment of ethyl tertiary butyl ether (ETBE) that when finalized will appear on the Integrated Risk Information System (IRIS) database.

  7. INFLUENCE OF METHYL TERT-BUTYL ETHER (MTBE) ON LAKE WATER ALGAE

    EPA Science Inventory

    Methyl tert-butyl ether (MTBE) has been used as an octane booster in gasoline in the United States since the 1970s. MTBE use increased greatly in the 1990s with the implementation of the Clean Air Act Amendments of 1990. The MTBE enhanced a more complete combustion of fuel hydroc...

  8. Spin trapping of radicals in tritiated methanol

    NASA Astrophysics Data System (ADS)

    Halpern, A.

    1984-01-01

    The radicals in [methyl- 3H]-methanol have been detected by spin trapping with PBN. Two radicals observed in deaerated samples at 273 K are methoxy and hydroxymethyl radicals. The relative contribution of these two radicals changes with the storage time, finally only the PBNCH 2OH adduct being observed. This behaviour is hypothetically explained as resulting from the secondary reactions with a product formed in methanol by internal β-radiolysis or otherwise, whose steadily increasing concentration accelerates the decay of the PBNCH 3O adduct.

  9. Physiological aspects of free-radical reactions.

    PubMed Central

    Yamazaki, I; Tamura, M; Nakajima, R; Nakamura, M

    1985-01-01

    Enzymes which catalyze the formation of free radicals in vitro will catalyze similar reactions in vivo. We believe that the formation of some kinds of free radicals has definite physiological meanings in metabolism. In this sense, the enzymes forming such free radicals are concluded to be in evolutionally advanced states. Elaborated structure and function of enzymes such as horseradish peroxidase and microsomal flavoproteins support the idea. Deleterious and side reactions caused by free radicals are assumed to be minimized in vivo by localizing the reactions, but this assumption should be verified by future studies. PMID:3007098

  10. Dynamics of Radical-Mediated Enzyme Catalyses

    NASA Astrophysics Data System (ADS)

    Warncke, Kurt

    1997-11-01

    An emergent class of enzymes harnesses the extreme reactivity of electron-deficient free radical species to perform some of the most difficult reactions in biology. The regio- and stereo-selectivity achieved by these enzymes defies long-held ideas that radical reactions are non-specific. The common primary step in these catalyses is metal- or metallocenter-assisted generation of an electron-deficient organic "initiator radical". The initiator radical abstracts a hydrogen atom from the substrate, opening a new reaction channel for rearrangement to the product. Our aim is to elucidate the detailed molecular mechanisms of the radical pair separation and radical rearrangement steps. Radical pair separation and substrate radical rearrangement are tracked by using time-resolved (10-7 to 10-3 s) techniques of pulsed-electron paramagnetic resonance spectroscopy (FT-EPR, ESEEM). Synchronous time-evolution of the reactions is attained by triggering with a visible laser pulse. Transient non-Boltzmann population of the states of the spin-coupled systems, and resultant electron spin polarization, facilitates study at or near room temperature under conditions where the enzymes are operative. The systems examined include ethanolamine deaminase, a vitamin B12 coenzyme-dependent enzyme, ribonucleotide reductase and photosynthetic reaction centers. The electronic and nuclear structural and kinetic information obtained from the pulsed-EPR studies is used to address how the initiator radicals are stabilized against deleterious recombination with the metal, and to distinguish the participation of concerted versus sequential rearrangement pathways.

  11. DNA Binding Hydroxyl Radical Probes

    PubMed Central

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

    2011-01-01

    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. PMID:22125376

  12. Students' Ideas and Radical Constructivism

    NASA Astrophysics Data System (ADS)

    Sánchez Gómez, Pedro J.

    2016-04-01

    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.

  13. Students' Ideas and Radical Constructivism

    NASA Astrophysics Data System (ADS)

    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.

  14. Radical surgery in septic abortion.

    PubMed

    Chatterjee, P; Ghosh, M; Ghosh, S

    1979-08-01

    At R.G. Kar Medical College Hospital, Calcutta, 10 cases of septic abortion from 1975-1977 were studied. Hysterectomies were preformed on 4 cases due to emergency situations including traumatised uterine fundus and perforated cervix, and on 6 cases after conservative treatment. Upon performing laparotomy in 9 cases, a uterine rent was detected; in 1 case there was a perforation in the posterior wall of the cervix, and in 5 cases mechanical obstructions due to internal adhesions to the uterine rent were found. 4 patients died primarily because of the patients seeking help too late. It is suggested that under high risk circumstances, laparotomy is advantageous to conservative medical management since bowel injuries and mechanical obstructions can only be detected by laparotomy. Radical surgery, however, should be undertaken before the patients general condition deteriorates to the point that the patient cannot tolerate surgical intervention. PMID:12336028

  15. Free radicals and ocular disease.

    PubMed

    Anderson, R E; Kretzer, F L; Rapp, L M

    1994-01-01

    Ames, Shigenaga, and Hagen recently published a thorough review of the relationship between oxidants, antioxidants, and degenerative diseases of ageing. They point out that only 9% of Americans daily consume the two fruits and three vegetables recommended by the National Cancer Institute and the National Research Council/National Academy of Science. In addition to antioxidants, these foodstuffs contain many essential micronutrients. To date, specific recommendations for antioxidant supplementation have not been made by any governmental agency or professional association. A number of clinical, basic, and epidemiological studies have implicated free radical induced lipid peroxidation in various ocular disorders. It would seem prudent that those persons at greatest risk for these disorders take some precautions, which could include sunglasses that filter ultraviolet light; hats that shield the eyes from direct sunlight; and the ingestion of fruits, vegetables, and antioxidants. PMID:7771292

  16. Disruption of auditory function by acute administration of a room odorizer containing butyl nitrite in rats

    SciTech Connect

    Fechter, L.D.; Richard, C.L.; Mungekar, M.; Gomez, J.; Strathern, D.

    1989-01-01

    Butyl nitrite is the predominant and presumed active ingredient in a variety of commercial preparations sold as ''room odorizers.'' These compounds have significant abuse potential, giving the user the sensation of a ''rush'', which may be related to their intense cardiovascular effects. The pharmacological properties of butyl nitrites are similar to those of amyl nitrite which is also abused for its psychological effects, but whose availability is limited by prescription for treatment of angina. A significant body of literature suggests that the inner ear is vulnerable to acute hypoxic exposure. Since butyl nitrite induces high levels of methemoglobin and also reduces blood pressure due to peripheral vasodilation, we hypothesized that this compound might produce auditory dysfunction. We studied the effect of acute exposure to a butyl nitrite ''room odorizer'' on 10- and 40-kHz auditory function in rats. A loss in auditory sensitivity was found at both frequencies on the day following administration of the compound. Auditory dysfunction tended to subside over the next several days at 40 kHz, although a significant loss of sensitivity for tones of 10 kHz was observed over a 6-day period after administration of the agent. Methemoglobin levels measured in rats of the same age were elevated significantly 30 and 60 min after butyl nitrite to levels of 30-45%. Methemoglobin levels were found to be normal 18 hr after administration when the first audiometric tests were conducted. The data suggest that auditory function in the middle of the rats' auditory range, 10 kHz, was disrupted for a longer period than was high-frequency (40 kHz) auditory function.

  17. Peroxy radical measurements with NCAR's chemical amplifier

    NASA Technical Reports Server (NTRS)

    Cantrell, Christopher; Shetter, Richard; Calvert, Jack G.

    1994-01-01

    The present NCAR instrument for HO2/RO2 measurements has been described previously. It is based on the reactions involving HO2, RO2, and HO radicals with CO and NO. Since (HO2) + (RO2) + (HO) is much greater than (HO) for most atmospheres, it is useful as a peroxy radical detector. Operation of the instrument depends on the creation of a chemical chain reaction which is initiated as HO2 and RO2 radicals in ambient air encounter added NO gas; this forms an NO2 molecule and an HO or RO radical: HO2(RO2) + NO yields HO(RO) + NO2. RO radicals react relatively efficiently with O2 to form an HO2 radical, and subsequently an HO-radical, by reaction with NO. CO gas added to the reaction chamber during part of the operating cycle, recycles the HO to HO2; HO + CO (+O2) yields HO2 + CO2. The reaction sequence may form several hundred NO2 molecules per HO2 (RO2) originally present, before chain termination occurs. The added CO is replaced by N2 addition periodically so that the chain reaction is suppressed, and a 'blank' signal resulting from NO2, O3 and possibly other NO2-forming species (non-chain processes) in ambient air is recorded. The difference between the signal with and without CO is proportional to the peroxy radical concentration. The NO2 produced is monitored using a sensitive luminol chemiluminescence detector system. In the NCAR instrument the length of the amplification chain is determined using a stable source of HO2 radicals (H2O2 thermal decomposition); the ratio of the signal seen with CO present to that with N2 present gives the sensitivity of the instrument to HO2 (molecules of NO2 formed/peroxy radical). The instrument is automated to carry out in hourly repeated cycles: (1) chain length determination; (2) NO2 calibration; and (3) linearity check on the response of signals. One minute averages of signals are normally recorded. The sensitivity of the instrument to detect peroxy radicals is in the pptv range. The present instrument has operated

  18. Electrochemical properties of the solvent SbCl/sub 3/-AlCl/sub 3/-N(1-butyl)pyridinium chloride and electrochemical and spectroelectrochemical studies of arene solutes

    SciTech Connect

    Chapman, D.M.; Mamantov, G.; Petrovic, C.; Smith, G.P.; Sorlie, M.

    1984-07-01

    Physical and electrochemical properties are reported for SbCl/sub 3/-AlCl/sub 3/-N-(1-butyl)pyridinium chloride (BPCl) mixtures that are liquid at ambient temperatures, and studies of the electrogeneration and open-circuit decay of some arene radical cations, both in this medium and in SbCl/sub 3/-KCl at elevated temperatures, are described. Specific conductivities, densities, and viscosities of the compositions (m/o (mole percent)) 60:19:21 (basic) and 60:21:19 (acidic) SbCl/sub 3/-AlCl/sub 3/-BPCl were measured over the temperature range 24/sup 0/-100/sup 0/C. For a potentiometric titration between the compositions 60:18:22 and 60:22:18 with SbCl/sub 3/ fixed at 60 m/o, the potential of the Sb(III)/Sb(0) couple increased by 0.43V at 27/sup 0/C. Electrochemical studies showed that perylene (Per), 9,10-dimethylanthracene (DMA), and 9,10diphenylanthracene (DPA) can be reversibly oxidized to their radical cations in a 60:19:21 melt, whereas the oxidation of anthracene (Ant) is irreversible. Spectroelectrochemical studies showed that Per radical cations were stable in this melt, those of DPA decayed very slowly, those of DMA decayed somewhat faster, and those of Ant were too transient to be observed optically. Similar degrees of stability were found for these radical cations in SbCl/sub 3/ containing 1 M KCl at elevated temperatures, and transient spectra of Ant radical cations were observed in this solvent.

  19. Alex Bloom, Pioneer of Radical State Education

    ERIC Educational Resources Information Center

    Fielding, Michael

    2005-01-01

    Alex Bloom is one of the greatest figures of radical state education in England. His approach to "personalised learning" and the development of a negotiated curriculum was immeasurably more profound and more inspiring than anything to emerge thus far from the current DfES. His approach to student voice was much more radical than anything presently…

  20. Radical Behaviorism and Buddhism: Complementarities and Conflicts

    ERIC Educational Resources Information Center

    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…

  1. Rearrangement of sulfonamidyl radicals with hydrogen migration

    SciTech Connect

    Troyanskii, E.I.; Lazareva, M.I.; Nikishin, G.I.

    1987-01-20

    One-step outlying oxidative chlorination of alkanesulfonamides by the action of the Na/sub 2/S/sub 2/O/sub 8/-CuCl/sub 2/ system via intermediate sulfonamidyl radicals gives 3- and 4-chloroalkanesulfonamides. Rearrangements of sulfonamidyl radicals with H atom migration from the sulfonyl segment predominates over rearrangement with H atom migration from the amide segment.

  2. What Is Radical in School Geography Today?

    ERIC Educational Resources Information Center

    Morgan, John

    2011-01-01

    This article addresses the question of what "radical school geography" might look like in the present historical moment. It traces the history of a distinctive "radical" tradition in school geography, most prominently associated with the work of John Huckle, who argued for the importance of understanding the content and pedagogy of school…

  3. Oxygen radical production by avian leukocytes.

    PubMed

    Conlon, P; Smith, D; Gowlett, T

    1991-04-01

    Oxygen radical production by heterophils of red-tailed hawks and chickens, and by neutrophils of calves, was evaluated in a chemiluminescence microassay. Leukocytes were isolated by centrifugation of blood in capillary tubes and then challenged with opsonized zymosan in the presence of luminol. Avian heterophils produced significantly fewer oxygen radicals than did bovine neutrophils. PMID:1884301

  4. Free Radical Mechanisms in Autoxidation Processes.

    ERIC Educational Resources Information Center

    Simic, Michael G.

    1981-01-01

    Discusses the use of steady-state radiation chemistry and pulse radiolysis for the generation of initial free radicals and formation of peroxy radicals in the autoxidation process. Provides information regarding the autoxidation process. Defines autoxidation reactions and antioxidant action. (CS)

  5. Radical Voices; A Film Course Study Guide.

    ERIC Educational Resources Information Center

    Kernan, Margot

    The leftist radical ideas current in the 1960s and 1970s are expressed in the films discussed in this cinema study guide. The radical film takes extreme and avant-garde approaches to the somewhat publicly taboo topics of sex, social issues, and religion. Among the films discussed, I AM CURIOUS (YELLOW) and SOMETHING DIFFERENT show women in their…

  6. Radical Constructivism: Between Realism and Solipsism.

    ERIC Educational Resources Information Center

    Martinez-Delgado, Alberto

    2002-01-01

    Criticizes radical constructivism of the Glasersfeld type, pointing out some contradictions between the declared radical principles and their theoretical and practical development. Suggests the possibility of an ideological substratum in the construction and hegemonic success of subjective constructivism, and briefly advances an alternative…

  7. Ideals Adrift: An Educational Approach to Radicalization

    ERIC Educational Resources Information Center

    van San, Marion; Sieckelinck, Stijn; de Winter, Micha

    2013-01-01

    These days, the radicalization of young people is above all viewed as a security risk. Almost all research into this phenomenon has been carried out from a legal, criminological or socio-psychological perspective with a focus on detecting and containing the risks posed by radicalization. In the light of the political developments since September…

  8. Electrophilicity and nucleophilicity index for radicals.

    PubMed

    De Vleeschouwer, Freija; Van Speybroeck, Veronique; Waroquier, Michel; Geerlings, Paul; De Proft, Frank

    2007-07-01

    Radicals can be regarded as electrophilic/nucleophilic, depending on their tendency to attack sites of relatively higher/lower electron density. In this paper, an electrophilicity scale, global as well as local, and a nucleophilicity scale for 35 radicals is reported. The global electrophilicity scale correlates well with the nucleophilicity scale, suggesting that these concepts are inversely related. PMID:17559221

  9. Synthesis and electronic structure determination of uranium(vi) ligand radical complexes.

    PubMed

    Herasymchuk, Khrystyna; Chiang, Linus; Hayes, Cassandra E; Brown, Matthew L; Ovens, Jeffrey S; Patrick, Brian O; Leznoff, Daniel B; Storr, Tim

    2016-08-01

    Pentagonal bipyramidal uranyl (UO2(2+)) complexes of salen ligands, N,N'-bis(3-tert-butyl-(5R)-salicylidene)-1,2-phenylenediamine, in which R = (t)Bu (1a), OMe (1b), and NMe2 (1c), were prepared and the electronic structure of the one-electron oxidized species [1a-c]+ were investigated in solution. The solid-state structures of 1a and 1b were solved by X-ray crystallography, and in the case of 1b an asymmetric UO2(2+) unit was found due to an intermolecular hydrogen bonding interaction. Electrochemical investigation of 1a-c by cyclic voltammetry showed that each complex exhibited at least one quasi-reversible redox process assigned to the oxidation of the phenolate moieties to phenoxyl radicals. The trend in redox potentials matches the electron-donating ability of the para-phenolate substituents. The electron paramagnetic resonance spectra of cations [1a-c]+ exhibited gav values of 1.997, 1.999, and 1.995, respectively, reflecting the ligand radical character of the oxidized forms, and in addition, spin-orbit coupling to the uranium centre. Chemical oxidation as monitored by ultraviolet-visible-near-infrared (UV-vis-NIR) spectroscopy afforded the one-electron oxidized species. Weak low energy intra-ligand charge transfer (CT) transitions were observed for [1a-c]+ indicating localization of the ligand radical to form a phenolate/phenoxyl radical species. Further analysis using density functional theory (DFT) calculations predicted a localized phenoxyl radical for [1a-c]+ with a small but significant contribution of the phenylenediamine unit to the spin density. Time-dependent DFT (TD-DFT) calculations provided further insight into the nature of the low energy transitions, predicting both phenolate to phenoxyl intervalence charge transfer (IVCT) and phenylenediamine to phenoxyl CT character. Overall, [1a-c]+ are determined to be relatively localized ligand radical complexes, in which localization is enhanced as the electron donating ability of the para

  10. Fluorescent dye-labelled polymer synthesis by nitroxide mediated radical polymerization

    NASA Astrophysics Data System (ADS)

    Kollár, Jozef; Chmela, Štefan; Hrčková, Ľudmila; Hrdlovič, Pavol

    2012-07-01

    New applications of polymers at advanced technologies demand increased requirements on their properties. These properties are influenced by molecular as well as supramolecular structure. Controlled radical polymerization mediated by stable nitroxides (NMP) or substituted alkoxyamines offers simple method for preparation of polymers with programmable structure of macromolecules which possess remarkable better physical as well as chemical properties. They can be used as a macro initiators for the synthesis of block copolymers. At the present time it has been generally accepted that the extent of "livingness" is high for all conversions [1-4]. To verify this statement a series of fluorescent dye-labelled regulators has been synthesized, spectrally characterized and used as the mediators of styrene and n-butyl acrylate polymerization. Direct quantification of dormant species concentration (extent of livingness) and calculation of molar mass of marked polymers was performed by absorption and/or emission spectroscopy. Controlled radical polymerization mediated by stable nitroxides bearing fluorescence mark represents unconventional approach for monitoring and evaluation of mechanism and kinetics of polymerization process. Results indicate that the extent of livingness is strongly influenced by conversion as well as mediator concentration. There is a clear tendency toward to decreasing amount of dormant species with increasing monomer conversion. Moreover, lower mediator concentration decreases livingness of polymerization process.

  11. Rate constant calculations of H-atom abstraction reactions from ethers by HȮ2 radicals.

    PubMed

    Mendes, Jorge; Zhou, Chong-Wen; Curran, Henry J

    2014-02-27

    In this work, we detail hydrogen atom abstraction reactions from six ethers by the hydroperoxyl radical, including dimethyl ether, ethyl methyl ether, propyl methyl ether, isopropyl methyl ether, butyl methyl ether, and isobutyl methyl ether, in order to test the effect of the functional group on the rate constant calculations. The Møller-Plesset (MP2) method with the 6-311G(d,p) basis set has been employed in the geometry optimizations and frequency calculations of all of the species involved in the above reaction systems. The connections between each transition state and the corresponding local minima have been determined by intrinsic reaction coordinate calculations. Energies are reported at the CCSD(T)/cc-pVTZ level of theory and include the zero-point energy corrections. As a benchmark in the electronic energy calculations, the CCSD(T)/CBS extrapolation was used for the reactions of dimethyl ether + HȮ2 radicals. A systematic calculation of the high-pressure limit rate constants has been performed using conventional transition-state theory, including asymmetric Eckart tunneling corrections, in the temperature range of 500-2000 K. The one dimensional hindrance potentials obtained at MP2/6-311G(d,p) for the reactants and transition states have been used to describe the low frequency torsional modes. Herein, we report the calculated individual, average, and total rate constants. A branching ratio analysis for every reaction site has also been performed. PMID:24483837

  12. Artifacts Generated During Azoalkane Peroxy Radical Oxidative Stress Testing of Pharmaceuticals Containing Primary and Secondary Amines.

    PubMed

    Nefliu, Marcela; Zelesky, Todd; Jansen, Patrick; Sluggett, Gregory W; Foti, Christopher; Baertschi, Steven W; Harmon, Paul A

    2015-12-01

    We report artifactual degradation of pharmaceutical compounds containing primary and secondary amines during peroxy radical-mediated oxidative stress carried out using azoalkane initiators. Two degradation products were detected when model drug compounds dissolved in methanol/water were heated to 40°C with radical initiators such as 2,2'-azobis(2-methylpropionitrile) (AIBN). The primary artifact was identified as an α-aminonitrile generated from the reaction of the amine group of the model drug with formaldehyde and hydrogen cyanide, generated as byproducts of the stress reaction. A minor artifact was generated from the reaction between the amine group and isocyanic acid, also a byproduct of the stress reaction. We report the effects of pH, initiator/drug molar ratio, and type of azoalkane initiator on the formation of these artifacts. Mass spectrometry and nuclear magnetic resonance were used for structure elucidation, whereas mechanistic studies, including stable isotope labeling experiments, cyanide analysis, and experiments exploring the effects of butylated hydroxyanisole addition, were employed to support the degradation pathways. PMID:26565996

  13. Electrochemical reduction of aromatic ketones in 1-butyl-3-methylimidazolium-based ionic liquids in the presence of carbon dioxide: the influence of the ketone substituent and the ionic liquid anion on bulk electrolysis product distribution.

    PubMed

    Zhao, Shu-Feng; Horne, Mike; Bond, Alan M; Zhang, Jie

    2015-07-15

    Electrochemical reduction of aromatic ketones, including acetophenone, benzophenone and 4-phenylbenzophenone, has been undertaken in 1-butyl-3-methylimidazolium-based ionic liquids containing tetrafluoroborate ([BF4](-)), trifluoromethanesulfonate ([TfO](-)) and tris(pentafluoroethyl)trifluorophosphate ([FAP](-)) anions in the presence of carbon dioxide in order to investigate the ketone substituent effect and the influence of the acidic proton on the imidazolium cation (C2-H) on bulk electrolysis product distribution. For acetophenone, the minor products were dimers (<10%) in all ionic liquids, which are the result of acetophenone radical anion coupling. For benzophenone and 4-phenylbenzophenone, no dimers were formed due to steric hindrance. In these cases, even though carboxylic acids were obtained, the main products generated were alcohols (>50%) derived from proton coupled electron transfer reactions involving the electrogenerated radical anions and C2-H. In the cases of both acetophenone and benzophenone, the product distribution is essentially independent of the ionic liquid anion. By contrast, 4-phenylbenzophenone shows a product distribution that is dependent on the ionic liquid anion. Higher yields of carboxylic acids (∼40%) are obtained with [TfO](-) and [FAP](-) anions because in these ionic liquids the C2-H is less acidic, making the formation of alcohol less favourable. In comparison with benzophenone, a higher yield of carboxylic acid (>30% versus ∼15%) was obtained with 4-phenylbenzophenone in all ionic liquids due to the weaker basicity of 4-phenylbenzophenone radical anion. PMID:26136079

  14. Roaming radical pathways for the decomposition of alkanes.

    SciTech Connect

    Harding, L. B.; Klippenstein, S. J.

    2010-01-01

    CASPT2 calculations predict the existence of roaming radical pathways for the decomposition of propane, n-butane, isobutane and neopentane. The roaming radical paths lead to the formation of an alkane and an alkene instead of the expected radical products. The predicted barriers for the roaming radical paths lie {approx}1 kcal/mol below the corresponding radical asymptotes.

  15. Biodegradation of the gasoline oxygenates methyl tert-butyl ether, ethyl tert-butyl ether, and tert-amyl methyl ether by propane-oxidizing bacteria.

    PubMed Central

    Steffan, R J; McClay, K; Vainberg, S; Condee, C W; Zhang, D

    1997-01-01

    Several propane-oxidizing bacteria were tested for their ability to degrade gasoline oxygenates, including methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and tert-amyl methyl ether (TAME). Both a laboratory strain and natural isolates were able to degrade each compound after growth on propane. When propane-grown strain ENV425 was incubated with 20 mg of uniformly labeled [14C]MTBE per liter, the strain converted > 60% of the added MTBE to 14CO2 in < 30 h. The initial oxidation of MTBE and ETBE resulted in the production of nearly stoichiometric amounts of tert-butyl alcohol (TBA), while the initial oxidation of TAME resulted in the production of tert-amyl alcohol. The methoxy methyl group of MTBE was oxidized to formaldehyde and ultimately to CO2. TBA was further oxidized to 2-methyl-2-hydroxy-1-propanol and then 2-hydroxy isobutyric acid; however, neither of these degradation products was an effective growth substrate for the propane oxidizers. Analysis of cell extracts of ENV425 and experiments with enzyme inhibitors implicated a soluble P-450 enzyme in the oxidation of both MTBE and TBA. MTBE was oxidized to TBA by camphor-grown Pseudomonas putida CAM, which produces the well-characterized P-450cam, but not by Rhodococcus rhodochrous 116, which produces two P-450 enzymes. Rates of MTBE degradation by propane-oxidizing strains ranged from 3.9 to 9.2 nmol/min/mg of cell protein at 28 degrees C, whereas TBA was oxidized at a rate of only 1.8 to 2.4 nmol/min/mg of cell protein at the same temperature. PMID:9361407

  16. Development of an arylthiobismuthine cocatalyst in organobismuthine-mediated living radical polymerization: applications for synthesis of ultrahigh molecular weight polystyrenes and polyacrylates.

    PubMed

    Kayahara, Eiichi; Yamago, Shigeru

    2009-02-25

    Diphenyl(2,6-dimesitylphenylthio)bismuthine (1a) serves as an excellent cocatalyst in organobismuthine-mediated living radical polymerization (BIRP). Both low and high molecular weight polystyrenes and poly(butyl acrylate)s (PBAs) with controlled molecular weights and low polydispersity indexes (PDIs) were synthesized by the addition of a catalytic amount of 1a to an organobismuthine chain-transfer agent, methyl 2-dimethylbismuthanyl-2-methylpropionate (3). The number-average molecular weight (M(n)) of the resulting polymers increases linearly with the monomer/3 ratio. Structurally well-defined polystyrenes with M(n)'s in the range from 1.0 x 10(4) to 2.0 x 10(5) and PDIs of 1.07-1.15 as well as PBAs with M(n)'s in the range from 1.2 x 10(4) to 2.8 x 10(6) and PDIs of 1.06-1.43 were successfully prepared under mild thermal conditions. Control experiments suggested that 1a reversibly reacts with the polymer-end radical to generate an organobismuthine dormant species and 2,6-dimesitylphenylthiyl radical (2a). This reaction avoids the occurrence of chain termination reactions involving the polymer-end radicals and avoids undesired loss of the bismuthanyl polymer end group. The bulky 2,6-dimesitylphenyl group attached to the sulfur atom may prevent the addition of thiyl radicals to the vinyl monomers to generate new polymer chains. PMID:19161331

  17. Choice of Bond Dissociation Enthalpies on which to Base the Stabilization Energies of Simple Radicals: DH(R-H)is Preferred because DH(R-Me) is Perturbed by Changes in Chain Branching

    SciTech Connect

    Poutsma, Marvin L

    2008-01-01

    The relative stabilization energies of radicals, SE(R ), along the simple series methyl/ethyl/i-propyl/t-butyl are known to vary in spread and even direction dependent on which dissociation enthalpies, DH(R-X), they are based on. Using a highly electronegative X is recognized as unwise, but it is not clear whether a choice of X = Me or X = R might not be preferred over the almost universal use of R = H. The enthalpies of isomerization of C4 radical pairs that vary only in the substitution pattern at the radical center but not in carbon skeleton illustrate that R = H is indeed the better choice. Comparisons in the context of recent predictive models for alkane and radical stability indicate that, while relative DH(R-H) values highlight the desired difference in substitution pattern at the radical center, relative DH(R-Me) values are perturbed by differences in skeletal branching or protobranching which are well-known to affect thermochemistry. As a result, SE(R ) values derived from relative DH(R-Me) values are consistently too small. The same pattern is illustrated for prim, sec, and tert allylic and benzylic radicals (larger SE(R )) and for the parent vinyl, phenyl, and ethynyl radicals (negative SE(R )).

  18. Halogenated silanes, radicals, and cations

    NASA Astrophysics Data System (ADS)

    Wang, Liming; He, Yi-Liang

    2008-09-01

    Quantum chemistry study has been carried out on the structure and energetics of halogenated silanes, radicals, and cations (SiHxXy0,+1, X = F, Cl, Br; x + y = 1-4). The geometries are optimized at B3LYP/6-31+G(2df,p) level. The adiabatic ionization energiess (IEas), relative energetics of cations, proton affinities (PAs) of silanes, and the enthalpies of formation are predicted using G3(CC) model chemistry. Non-classical ion complex structures are found for hydrogenated cations and transition states connecting classical and non-classical structures are also located. The most stable cations for silylene and silyl radicals have their classical divalent and trivalent structures, and those for silanes have non-classical structures except for SiH3Br+ and SiH2Br2+. The non-classical structures for halosilane cations imply difficulty in experimentally measurement of the adiabatic ionization energies using photoionization or photoelectron studies. For SiH3X, SiH2X2, and SiHX3, the G3(CC) adiabatic IEas to classical ionic structures closest to their neutrals agree better with the photoelectron spectroscopic measurements. The transition states between classical and non-classical structures also hamper the photoionization determination of the appearance energies for silylene cations from silanes. The G3(CC) results for SiHx0,+1 agree excellently with the photoionization mass spectrometric study, and the results for fluorinated and chlorinated species also agree with the previous theoretical predictions at correlation levels from BAC-MP4 to CCSD(T)/CBS. The predicted enthalpy differences between SiH2Cl+, SiHCl2+, and SiCl3+ are also in accordance with previous kinetics study. The G3(CC) results show large discrepancies to the collision-induced charge transfer and/or dissociation reactions involving SiFx+ and SiClx+ ions, for which the G3(CC) enthalpies of formation are also significantly differed from the previous theoretical predictions, especially on SiFx+ (x = 2-4). The G3

  19. Pilot study of radical hysterectomy versus radical trachelectomy on sexual distress.

    PubMed

    Brotto, Lori A; Smith, Kelly B; Breckon, Erin; Plante, Marie

    2013-01-01

    Radical trachelectomy, which leaves the uterus intact, has emerged as a desirable surgical option for eligible women with early-stage cervical cancer who wish to preserve fertility. The available data suggest excellent obstetrical outcomes with radical trachelectomy, and no differences in sexual responding between radical trachelectomy and radical hysterectomy. There is a need to examine the effect of radical hysterectomy on sexual distress given that it is distinct from sexual function. Participants were 34 women diagnosed with early-stage cervical cancer. The authors report 1-month postsurgery data for 29 women (radical hysterectomy group: n = 17, M age = 41.8 years; radical trachelectomy group: n = 12, M age = 31.8 years), and 6-month follow-up data on 26 women. Whereas both groups experienced an increase in sex-related distress immediately after surgery, distress continued to increase 6 months after surgery for the radical hysterectomy group but decreased in the radical trachelectomy group. There were no between-group differences in mood, anxiety, or general measures of health. The decrease in sex-related distress in the radical trachelectomy but not in the radical hysterectomy group suggests that the preservation of fertility may have attenuated sex-related distress. Care providers should counsel women exploring surgical options for cervical cancer about potential sex distress-related sequelae. PMID:23656625

  20. Radiolytic generation of radical cations in xenon matrices. Tetramethylcyclopropane radical cation and its transformations

    SciTech Connect

    Qin, X.Z.; Trifunac, A.D. )

    1990-04-05

    Radiolytic generation of radical cations in xenon matrices containing electron scavengers is illustrated by studying the 1,1,2,2-tetramethylcyclopropane radical cation. Dilute and concentrated solutions of tetramethylcyclopropane in xenon without electron scavengers and neat tetramethylcyclopropane yielded neutral radicals upon {gamma}-irradiation. Speculation on the mechanisms of radical formation is presented. The radical species observed in the {gamma}-irradiation of neat tetramethylcyclopropane appears to be identical with the paramagnetic species observed in CF{sub 2}ClCFCl{sub 2} above 120 K, suggesting that a neutral radical rather than the ring-opened distonic radical cation is observed in the CF{sub 2}ClCFCl{sub 2} matrix.

  1. Characteristics of Radical Reactions, Spin Rules, and a Suggestion for the Consistent Use of a Dot on Radical Species

    ERIC Educational Resources Information Center

    Wojnarovits, Laszlo

    2011-01-01

    In many chemical reactions, reactive radicals have been shown to be transient intermediates. The free radical character of a chemical species is often, but not always, indicated by adding a superscript dot to the chemical formula. A consistent use of this radical symbol on all species that have radical character is suggested. Free radicals have a…

  2. Kinetics of Propargyl Radical Dissociation.

    PubMed

    Klippenstein, Stephen J; Miller, James A; Jasper, Ahren W

    2015-07-16

    Due to the prominent role of the propargyl radical for hydrocarbon growth within combustion environments, it is important to understand the kinetics of its formation and loss. The ab initio transition state theory-based master equation method is used to obtain theoretical kinetic predictions for the temperature and pressure dependence of the thermal decomposition of propargyl, which may be its primary loss channel under some conditions. The potential energy surface for the decomposition of propargyl is first mapped at a high level of theory with a combination of coupled cluster and multireference perturbation calculations. Variational transition state theory is then used to predict the microcanonical rate coefficients, which are subsequently implemented within the multiple-well multiple-channel master equation. A variety of energy transfer parameters are considered, and the sensitivity of the thermal rate predictions to these parameters is explored. The predictions for the thermal decomposition rate coefficient are found to be in good agreement with the limited experimental data. Modified Arrhenius representations of the rate constants are reported for utility in combustion modeling. PMID:25871530

  3. Generation of 8-epi-prostaglandin F(2alpha) in isolated rat kidney glomeruli by a radical-independent mechanism.

    PubMed

    Klein, T; Neuhaus, K; Reutter, F; Nüsing, R M

    2001-07-01

    Isoprostanes comprise a group of free radical-catalyzed products of arachidonic acid. However, there is recent evidence pointing towards an enzyme-dependent formation of isoprostanes. With the use of isolated rat glomeruli we addressed the mechanisms of isoprostane generation. Synthesis of prostanoids and isoprostanes, including 8-epi-PGF(2alpha), was studied under conditions favouring radical formation. Cultured glomeruli formed different prostanoids including 8-epi-PGF(2alpha). Upon LPS challenge cyclo-oxygenase (COX)-2 expression was enhanced, and this was paralleled by a 2 - 9-fold increase in prostanoid formation, including isoprostanes. Addition of COX-isoform unselective inhibitors (diclofenac, indomethacin) or a selective inhibitor (NS-398) suppressed the synthesis of prostanoids, 8-epi-PGF(2alpha) and total isoprostane fraction; however, inhibition of the latter was less pronounced. Antioxidants such as butylated hydroxytoluene (BHT), nordihydroguaiaretic acid (NDGA), or dimethylurea exhibited an only minimal inhibitory effect on 8-epi-PGF(2alpha) synthesis. Moreover, ROS-generating drugs (menadione, methylviologen) or NADPH-driven radical formation were unable to cause the generation of significant amounts of 8-epi-PGF(2alpha) by rat glomeruli. In contrast, the total isoprostane fraction could be increased by menadione addition. These data provide further evidence for a radical-independent, but COX-dependent formation of 8-epi-PGF(2alpha) in renal tissue. Regarding the other isoprostanes, both radicals and COX enzymes contribute to their formation. Based on our data we assume that elevated release of vasoactive 8-epi-PGF(2alpha) has to be expected under conditions when the prostanoid system in the kidney is stimulated, e.g. under inflammatory conditions. Regarding renal oxidative injuries, the usefulness of 8-epi-PGF(2alpha) as a representative marker molecule of oxidative stress has to be questioned. PMID:11429387

  4. MICROWAVE-ASSISTED PREPARATION OF 1-BUTYL-3-METHYLIMIDAZOLIUM TETRACHLOROGALLATE AND ITS CATALYTIC USE IN ACETAL FORMATION UNDER MILD CONDITIONS

    EPA Science Inventory

    1-Butyl-3-methylimidazolium tetrachlorogallate, [bmim][GaCl4], prepared via microwave-assisted protocol, is found to be an active catalyst for the efficient acetalization of aldehydes under mild conditions.

  5. Portal Hypertension Secondary to Spontaneous Arterio-Portal Venous Fistulas: Transcatheter Arterial Embolization with n-Butyl Cyanoacrylate and Microcoils

    SciTech Connect

    Yamagami, Takuji; Nakamura, Toshiyuki; Nishimura, Tsunehiko

    2000-09-15

    We report a 73-year-old man with recurrent variceal bleeding due to portal hypertension caused by multiple intrahepatic arterio-portal venous fistulas, which were successfully occluded by embolization with n-butyl cyanoacrylate and micro-coils.

  6. Transcatheter Embolization of a Coronary Fistula Originating from the Left Anterior Descending Artery by Using N-Butyl 2-Cyanoacrylate

    SciTech Connect

    Karagoz, Tevfik; Celiker, Alpay E-mail: tkaraqoz@hacettepe.edu.tr; Cil, Barbaros; Cekirge, Saruhan

    2004-11-15

    In this report, we describe a successful percutaneous transcatheter n-butyl 2-cyanoacrylate embolization of a coronary fistula originating from the left anterior descending artery in an adolescent with unexpected recurrent attacks of myocardial ischemia.

  7. Studies on acrylated epoxydised triglyceride resin-co-butyl methacrylate towards the development of biodegradable pressure sensitive adhesives.

    PubMed

    David, S Begila; Sathiyalekshmi, K; Gnana Raj, G Allen

    2009-12-01

    The potential chemical utility of Soya bean oil for the preparation of novel biodegradable polymeric pressure sensitive adhesive has been investigated. Epoxy resin was prepared through in situ epoxidation of Soya bean oil under controlled reaction conditions. Acrylated epoxidised triglyceride resin (AET resin) and copolymer of AET resin with butyl methacrylate were prepared and evaluated. Higher the concentration of butyl methacrylate higher is the degree of copolymerization of AET resin with butyl methacrylate. An optimum concentration of AET resin with butyl methacrylate (100 : 0.40) yields favourable shear holding time and peel strength to qualify as pressure sensitive adhesive. The candidate PSA formulation is biodegradable with antimicrobial activity against gram positive S. aureus ATCC 25923. PMID:18584126

  8. New blends of ethylene-butyl acrylate copolymers with thermoplastic starch. Characterization and bacterial biodegradation.

    PubMed

    Morro, A; Catalina, F; Corrales, T; Pablos, J L; Marin, I; Abrusci, C

    2016-09-20

    Ethylene-butyl acrylate copolymer (EBA) with 13% of butyl acrylate content was used to produce blends with 10, 30 and 60% of thermoplastic starch (TPS) plasticized with glycerol. Ethylene-acrylic acid copolymer (EAA) was used as compatibilizer at 20% content with respect to EBA. The blends were characterized by X-ray diffraction, ATR-Fourier Transform Infrared Spectroscopy (ATR-FTIR), Scanning Electron Microscopy (SEM), water-Contact Angle measurements (CA), Differential Scanning Calorimetry (DSC) and Stress-strain mechanical tests. Initiated autoxidation of the polymer blends was studied by chemiluminescence (CL) confirming that the presence of the polyolefin-TPS interphase did not substantially affect the oxidative thermostability of the materials. Three bacterial species have been isolated from the blend films buried in soil and identified as Bacillus subtilis, Bacillus borstelensis and Bacillus licheniformis. Biodegradation of the blends (28days at 45°C) was evaluated by carbon dioxide measurement using the indirect impedance technique. PMID:27261731

  9. Aging of Weapon Seals – An Update on Butyl O-ring Issues

    SciTech Connect

    Wilson, Mark H.

    2011-07-13

    During testing under the Enhanced Surveillance Campaign in 2001, preliminary data detected a previously unknown and potentially serious concern with recently procured butyl o-rings on several programs. All butyl o-rings molded from a proprietary formulation throughout the period circa 1999 through 2001 had less than a full cure. Engineering judgment was that under curing is detrimental and could possibly lead to sub-optimum performance or, in the worst case, premature seal failure. An aging study was undertaken to ensure that suspect o-rings installed in the stockpile will retain sufficient sealing force for a minimum ten-year service life. A new prediction model developed for this study indicates suspect o-rings do not need to be replaced before the ten-year service life. Long-term testing results are reported on a yearly basis to validate the prediction model. This report documents the aging results for the period September 2002 to January 2011.

  10. Crystal structure of the co-crystal butyl­paraben–isonicotinamide (1/1)

    PubMed Central

    Bhardwaj, Rajni M.; Yang, Huaiyu; Florence, Alastair J.

    2016-01-01

    The title 1:1 co-crystal, C11H14O3·C6H6N2O [systematic name: butyl 4-hy­droxy­benzoate–isonicotinamide (1/1)], crystallizes with one mol­ecule of butyl­paraben (BPN) and one mol­ecule of isonicotinamide (ISN) in the asymmetric unit. In the crystal, BPN and ISN mol­ecules form hydrogen-bonded (O—H⋯N and N—H⋯O) dimers of paired BPN and ISN mol­ecules. These dimers are further connected to each other via N—H⋯O=C hydrogen bonds, creating ribbons in [011] which further stack along the a axis to form a layered structure with short C⋯C contacts of 3.285 (3) Å. Packing inter­actions within the crystal structure were assessed using PIXEL calculations. PMID:26870584

  11. Bio-Source of di-n-butyl phthalate production by filamentous fungi

    NASA Astrophysics Data System (ADS)

    Tian, Congkui; Ni, Jinren; Chang, Fang; Liu, Sitong; Xu, Nan; Sun, Weiling; Xie, Yuan; Guo, Yongzhao; Ma, Yanrong; Yang, Zhenxing; Dang, Chenyuan; Huang, Yuefei; Tian, Zhexian; Wang, Yiping

    2016-02-01

    Although DBP (di-n-butyl phthalate) is commonly encountered as an artificially-synthesized plasticizer with potential to impair fertility, we confirm that it can also be biosynthesized as microbial secondary metabolites from naturally occurring filamentous fungi strains cultured either in an artificial medium or natural water. Using the excreted crude enzyme from the fungi for catalyzing a variety of substrates, we found that the fungal generation of DBP was largely through shikimic acid pathway, which was assembled by phthalic acid with butyl alcohol through esterification. The DBP production ability of the fungi was primarily influenced by fungal spore density and incubation temperature. This study indicates an important alternative natural waterborne source of DBP in addition to artificial synthesis, which implied fungal contribution must be highlighted for future source control and risk management of DBP.

  12. Bio-Source of di-n-butyl phthalate production by filamentous fungi

    PubMed Central

    Tian, Congkui; Ni, Jinren; Chang, Fang; Liu, Sitong; Xu, Nan; Sun, Weiling; Xie, Yuan; Guo, Yongzhao; Ma, Yanrong; Yang, Zhenxing; Dang, Chenyuan; Huang, Yuefei; Tian, Zhexian; Wang, Yiping

    2016-01-01

    Although DBP (di-n-butyl phthalate) is commonly encountered as an artificially-synthesized plasticizer with potential to impair fertility, we confirm that it can also be biosynthesized as microbial secondary metabolites from naturally occurring filamentous fungi strains cultured either in an artificial medium or natural water. Using the excreted crude enzyme from the fungi for catalyzing a variety of substrates, we found that the fungal generation of DBP was largely through shikimic acid pathway, which was assembled by phthalic acid with butyl alcohol through esterification. The DBP production ability of the fungi was primarily influenced by fungal spore density and incubation temperature. This study indicates an important alternative natural waterborne source of DBP in addition to artificial synthesis, which implied fungal contribution must be highlighted for future source control and risk management of DBP. PMID:26857605

  13. The oxidation of 2,6-di-tert-butyl-4-methylphenol

    USGS Publications Warehouse

    Yohe, G.R.; Dunbar, J.E.; Pedrotti, R.L.; Scheidt, F.M.; Lee, F.G.H.; Smith, E.C.

    1956-01-01

    The products formed in the oxidation of 2,6-di-tert-butyl-4-methylphenol with oxygen and sodium hydroxide at about 100?? are 3,5-di-tert-butyl-4-hydroxybenzaldehyde, trimethylacetic acid, an acidic compound C14H22O3, and probably 2,6-di-tert-butylbenzoquinone (which was actually isolated in the similar oxidation of the above-named benzaldehyde), in addition to compounds previously reported. Some of the properties of C14H22O3 are given, and the oxidation of it to 2,3-di-tert-butylsuccinic anhydride is described, but assignment of structure is reserved pending the completion of more experimental work.

  14. Permeability of Molecular Hydrogen and Water Vapor Through Butyl Rubber at Ambient Temperature

    SciTech Connect

    Zeigler, K.

    1992-04-09

    The preparation of the Safety Analysis Report for the 233-H Replacement Tritium Facility (RTF) requires permeation constants of hydrogen isotopes through butyl rubber, to estimate possible worker exposure given a certain level of tritium in the confinement gloveboxes. Literature values of the permeability constants for hydrogen isotopes and water vapor through butyl rubber at ambient temperature (22-25 C) have been converted to common units and are tabulated (Tables I and II). Permeation rates of tritiated species are the same as that of protium species, within experimental error. Thus, molecular protium and normal water vapor data serve to estimate tritium permeation rates. Because of vendor to vendor variability of permeability, especially of water vapor, vendor measurements of water vapor permeability should continue to be used to estimate permeation in SRS processes.

  15. Permeability of Molecular Hydrogen and Water Vapor Through Butyl Rubber at Ambient Temperature

    SciTech Connect

    Clark, Elliot A.

    1992-04-09

    The preparation of the Safety Analysis Report for the 233-H Replacement Tritium Facility (RTF) requires permeation constants of hydrogen isotopes through butyl rubber, to estimate possible worker exposure given a certain level of tritium in the confinement gloveboxes. Literature values of the permeability constants for hydrogen isotopes and water vapor through butyl rubber at ambient temperature (22-25 C) have been converted to common units and are tabulated (Tables I and II). Permeation rates of tritiated species are the same as that of protium species, within experimental error. Thus, molecular protium and normal water vapor data serve to estimate tritium permeation rates. Because of vendor-to-vendor variability of permeability, especially of water vapor, vendor measurements of water vapor permeability should continue to be used to estimate permeation in SRS processes.

  16. Biotransformation of methyl tert-butyl ether by human cytochrome P450 2A6.

    PubMed

    Shamsipur, Mojtaba; Miran Beigi, Ali Akbar; Teymouri, Mohammad; Poursaberi, Tahereh; Mostafavi, S Mojtaba; Soleimani, Parviz; Chitsazian, Fereshteh; Tash, Shahram Abolhassan

    2012-04-01

    Methyl tert-butyl ether (MTBE) is widely used as gasoline oxygenate and octane number enhancer for more complete combustion in order to reduce the air pollution caused by motor vehicle exhaust. The possible adverse effects of MTBE on human health are of major public concern. However, information on the metabolism of MTBE in human tissues is scarce. The present study demonstrates that human cytochrome P450 2A6 is able to metabolize MTBE to tert-butyl alcohol (TBA), a major circulating metabolite and marker for exposure to MTBE. As CYP2A6 is known to be constitutively expressed in human livers, we infer that it may play a significant role in metabolism of gasoline ethers in liver tissue. PMID:21915685

  17. No Promoting Effect of Ethyl Tertiary-butyl Ether (ETBE) on Rat Urinary Bladder Carcinogenesis Initiated with N-Butyl-N-(4-hydroxybutyl)nitrosamine

    PubMed Central

    Hagiwara, Akihiro; Imai, Norio; Doi, Yuko; Suguro, Mayuko; Kawabe, Mayumi; Furukawa, Fumio; Nagano, Kasuke; Fukushima, Shoji

    2013-01-01

    The effects of ethyl tertiary-butyl ether (ETBE) on two-stage urinary bladder carcinogenesis in male F344 rats initiated with N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) were investigated at various dose levels with regard to possible promoting activity. Groups of 30 rats were given drinking water containing 500 ppm BBN, as an initiator, for 4 weeks and starting one week thereafter received ETBE by gavage (daily, 7 days/week) at dose levels of 0 (control), 100, 300, 500 or 1000 mg/kg/day until experimental week 36. No statistically significant differences in incidences of preneoplastic lesions, papillomas, and carcinomas of the urinary bladder were evident in rats treated with 100–1000 mg/kg/day ETBE as compared with control values. Furthermore, the average numbers of preneoplastic or neoplastic lesions per unit length of basement membrane in rats given 100–1000 mg/kg/day ETBE were also comparable to control values. However, papillomatosis of the urinary bladder was found in 4 out of 30 rats (13%) in the group given 1000 mg/kg/day ETBE, and soft stones in the urinary bladder were found in 3 out of these 4 rats. The results thus demonstrated that ETBE did not exert promotional activity on urinary bladder carcinogenesis. However, papillomatosis of the urinary bladder developed in small numbers of the rats given ETBE at 1000 mg/kg/day but not in rats given 500 mg/kg/day or lower doses. PMID:24526807

  18. Combined toxicities of methyl tert-butyl ether and its metabolite tert-butyl alcohol on earthworms via different exposure routes.

    PubMed

    Lee, Woo-Mi; Yoon, Youngdae; An, Youn-Joo

    2015-06-01

    Methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) are among the major soil contaminants that threaten the health of soil ecosystems. Many MTBE-contaminated sites accumulate TBA, because TBA is the intermediate of MTBE biodegradation. To access the risk of MTBE and TBA in soil, we investigated the combined toxicities of MTBE and TBA using two earthworm species, Perionyx excavatus and Eisenia andrei, as well as the toxic effects via different exposure routes. The combined toxicity showed weak antagonistic effects (LC50mix values were slightly greater than 1.0), and sensitivity toward same pollutants differed in the two earthworm species. Moreover, the toxicity of MTBE and TBA was also affected by the exposure route; both filter paper and artificial soil tests showed that dermal-only exposure to MTBE had an even greater toxic effect than combined dermal and oral exposure. Thus, we suggest that diverse environmental factors including organic materials, the physicochemical properties of the contact media, and the exposure routes of the organism, should be taken into consideration when assessing the effects of pollutants on organisms in diverse environmental systems. PMID:25706436

  19. Effect of thyme/cumin essential oils and butylated hydroxyl anisole/butylated hydroxyl toluene on physicochemical properties and oxidative/microbial stability of chicken patties.

    PubMed

    Sariçoban, Cemalettin; Yilmaz, Mustafa Tahsin

    2014-02-01

    In this study, effects of thyme/cumin essential oils (EO) and butylated hydroxyl anisole (BHA)/butylated hydroxyl toluene (BHT) on physicochemical properties and storage stability of chicken patties were compared in different storage periods (0, 3, 7, 14, 21, and 28 d). It was found that there were significant (P < 0.05) differences between physicochemical properties of patty samples treated with EO and the synthetic antioxidants. The EO showed similar performance to those of BHA and BHT in limiting TBARS values of chicken patty samples. Similarity in performance was also the case for microbial stability (total aerobic mesophilic, psychrotrophic, lactic acid, and coliform bacteria as well as molds and yeasts); namely, their effects were significant (P < 0.05). Effect of thyme EO was significant (P < 0.05) and remarkable, not allowing any coliform bacteria to grow in the samples. Given that EO were obtained from natural sources, the data suggested that the EO might be more useful than their synthetic counterparts, BHA and BHT, as additives for chicken patties to maintain oxidative/microbial stability and increase shelf life. PMID:24570469

  20. Molecular structures of tert-butyl alcohol and tert-butyl methyl ether as studied by gas electron diffraction combined with vibrational spectroscopy

    NASA Astrophysics Data System (ADS)

    Suwa, Atsuhiko; Ohta, Hiroshi; Konaka, Shigehiro

    1988-02-01

    The molecular of tert-butyl alcohol (TBA) and tert-butyl methyl ether (TBME) have been determined by gas electron diffraction. Vibrational spectra have been measured for TBME. Normal coordinate analyses have been performed to obtain harmonic force fields and to calculate mean amplitudes and shrinkage corrections. Principal bond lengths ( rg) and angles ( rα are: r(OH) = 1.016(14) Å, r(CO) = 1.446(4) Å, r(CC) - 1.529(2) Å, ∠COH = 108(3)° and ∠CCC = 110.9(2)° for TBA r(C 2O) = 1.448(4) Å, r(CC) = 1.532(2) Å, ∠COC = 118.9(14)° and ∠CCC = 111.1(2)° for TBME. The results have been compared with values from molecular mechanics and SCF MO calculations. The observed geometry for TBA is consistent with the rotational constant reported by Valenzuela. The rg(CO) value of TBA is about 0.02 Å larger than that of methanol. The values of rg(C 2O) and ∠COC of TBME are about 0.03 Å and 7° larger than the corresponding values of dimethyl ether and ethyl methyl ether.

  1. Radical scavenging activities of niacin-related compounds.

    PubMed

    Ogata, Shin; Takeuchi, Masayo; Teradaira, Shin; Yamamoto, Naokuni; Iwata, Keiko; Okumura, Katsuzumi; Taguchi, Hiroshi

    2002-03-01

    We investigated whether niacin-related compounds had radical-scavenging activity by electron spin resonance methods. Many compounds, but not trigonelline, had radical-scavenging activity against hydroxyl radicals. However, for the nitric oxide radical and 1,1-diphenyl-2-picrylhydrazyl radical, only nicotinic acid hydrazide and isonicotinic acid hydrazide had scavenging activities. These results suggest that the moiety of hydrazide might have an important role in scavenging abilities of various radicals. PMID:12005062

  2. Competition of charge- versus radical-directed fragmentation of gas-phase protonated cysteine sulfinyl radicals.

    PubMed

    Love, Chasity B; Tan, Lei; Francisco, Joseph S; Xia, Yu

    2013-04-24

    The fragmentation behavior of various cysteine sulfinyl ions (intact, N-acetylated, and O-methylated), new members of the gas-phase amino acid radical ion family, was investigated by low-energy collision-induced dissociation (CID). The dominant fragmentation channel for the protonated cysteine sulfinyl radicals ((SO•)Cys) was the radical-directed Cα-Cβ homolytic cleavage, resulting in the formation of glycyl radical ions and loss of CH2SO. This channel, however, was not observed for protonated N-acetylated cysteine sulfinyl radicals (Ac-(SO•)Cys); instead, charge-directed H2O loss followed immediately by SH loss prevailed. Counterintuitively, the H2O loss did not derive from the carboxyl group but involved the sulfinyl oxygen, a proton, and a Cβ hydrogen atom. Theoretical calculations suggested that N-acetylation significantly increases the barrier (~14 kcal mol(-1)) for the radical-directed fragmentation channel because of its reduced capability to stabilize the thus-formed glycyl radical ions via the captodative effect. N-Acetylation also assists in moving the proton to the sulfinyl site, which reduces the barrier for H2O loss. Our studies demonstrate that for cysteine sulfinyl radical ions, the stability of the product ions (glycyl radical ions) and the location of the charge (proton) can significantly modulate the competition between radical- and charge-directed fragmentation. PMID:23527556

  3. Expanding Radical SAM Chemistry by Using Radical Addition Reactions and SAM Analogues.

    PubMed

    Ji, Xinjian; Li, Yongzhen; Xie, Liqi; Lu, Haojie; Ding, Wei; Zhang, Qi

    2016-09-19

    Radical S-adenosyl-l-methionine (SAM) enzymes utilize a [4Fe-4S] cluster to bind SAM and reductively cleave its carbon-sulfur bond to produce a highly reactive 5'-deoxyadenosyl (dAdo) radical. In almost all cases, the dAdo radical abstracts a hydrogen atom from the substrates or from enzymes, thereby initiating a highly diverse array of reactions. Herein, we report a change of the dAdo radical-based chemistry from hydrogen abstraction to radical addition in the reaction of the radical SAM enzyme NosL. This change was achieved by using a substrate analogue containing an olefin moiety. We also showed that two SAM analogues containing different nucleoside functionalities initiate the radical-based reactions with high efficiencies. The radical adduct with the olefin produced in the reaction was found to undergo two divergent reactions, and the mechanistic insights into this process were investigated in detail. Our study demonstrates a promising strategy in expanding radical SAM chemistry, providing an effective way to access nucleoside-containing compounds by using radical SAM-dependent reactions. PMID:27573794

  4. Use of a Balloon and N-Butyl-2-Cyanoacrylate for Treatment of Arteriovenous Fistula

    SciTech Connect

    Doenmez, Halil Mavili, Ertugrul; Toker, Birguel; Oztuerk, M. Halil; Soylu, Serra O.; Hekimoglu, Baki

    2008-07-15

    We report a patient who developed a large arteriovenous fistula in right lower extremity after gunshot injury. Because other endovascular methods failed, the patient was successfully treated with concomitant use of detachable latex balloon and N-butyl-2-cyanoacrylate (NBCA). The combination of detachable balloon and NBCA can be effectively used for endovascular treatment of peripheral arteriovenous fistulas in selected cases when effective embolization could not be achieved with other embolizing agents or their various combinations.

  5. Temperature effect on tert-butyl alcohol (TBA) biodegradation kinetics in hyporheic zone soils

    PubMed Central

    Greenwood, Mark H; Sims, Ronald C; McLean, Joan E; Doucette, William J

    2007-01-01

    Background Remediation of tert-butyl alcohol (TBA) in subsurface waters should be taken into consideration at reformulated gasoline contaminated sites since it is a biodegradation intermediate of methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and tert-butyl formate (TBF). The effect of temperature on TBA biodegradation has not been not been published in the literature. Methods Biodegradation of [U 14C] TBA was determined using hyporheic zone soil microcosms. Results First order mineralization rate constants of TBA at 5°C, 15°C and 25°C were 7.84 ± 0.14 × 10-3, 9.07 ± 0.09 × 10-3, and 15.3 ± 0.3 × 10-3 days-1, respectively (or 2.86 ± 0.05, 3.31 ± 0.03, 5.60 ± 0.14 years-1, respectively). Temperature had a statistically significant effect on the mineralization rates and was modelled using the Arrhenius equation with frequency factor (A) and activation energy (Ea) of 154 day-1 and 23,006 mol/J, respectively. Conclusion Results of this study are the first to determine mineralization rates of TBA for different temperatures. The kinetic rates determined in this study can be used in groundwater fate and transport modelling of TBA at the Ronan, MT site and provide an estimate for TBA removal at other similar shallow aquifer sites and hyporheic zones as a function of seasonal change in temperature. PMID:17877835

  6. NMR study of products of the reaction of fulvenes with vinyl butyl ether

    SciTech Connect

    Yashtulov, N.A.; Dobrovinskii, L.A.; Cherkasov, A.N.; Kamyshina, L.G.; Livshits, R.M.

    1987-08-20

    The formation of copolymers with conjugated double bonds was proven by /sup 1/H and /sup 13/C NMR in cationic copolymerization of 6,6-disubstituted pentafulvenes with vinyl butyl ether. The composition and structure of the copolymers were determined. It was shown that it is possible to find the constants of copolymerization and distribution of the microblock nature in relation to the composition of the copolymers.

  7. Bis(1-tert-butyl-1H-imidazole-κN3)dichloridocobalt(II).

    PubMed

    Herdtweck, Eberhardt; Zeller, Alexander; Strassner, Thomas

    2012-06-01

    In the crystal structure of the title compound, [CoCl(2)(C(7)H(12)N(2))(2)], molecular units are formed by coordination of the unsubstituted N atoms of two tert-butyl-substituted imidazole molecules and two chloride ligands, which distinguishes the complex from structures of imidazolium-based dications with tetrachloridocobaltate dianions. There are two crystallographically independent molecules in the asymmetric unit, related by a noncrystallographic inversion centre. PMID:22669189

  8. Stark effect in the J = 3 4 microwave line of tert-butyl chloride molecule

    NASA Astrophysics Data System (ADS)

    Gierszal, S.; Mis-Kuzminska, E.; Stankowski, J.; Galica, J.

    1984-03-01

    Stark effect in the J = 3 - 4 transition spectrum of the tert-butyl chloride has been investigated. The perturbation of the rotational levels by combined effect of the quadrupole and an intermediate electric fields was calculated and used for identify the Stark components. The rotational spectrum of tert-butyl chloride /CH 3/ 3CCl is characterised by the rotational constants A = 4518.70 MHz[1] and B = 3017.85 MHz, dipole moment U= 2.12 D, and quadrupole interaction constant eqQ = -67.58 MHz [2,3]. The energy of rotational states of the tert-butyl chloride molecule is described by the Hamiltonian ? where H 0 is the unperturbed rotational energy, H Q that of interaction of the angular momentum and quadrupole moment of the chlorine nucleus, and H E the Stark energy. Since H Q ˜ H E for the electric field strengths applied during the present investigation, we are dealing with the case of intermediate fields. To solve the problem theoretically we had recourse to the representation in F-space and calculated the energy for the perturbation H Q + H E as done by Low and Townes [4]. The theoretical distances of the Stark components from the absorption line of tert-butyl chloride for various electric field strengths at J = 3 - 4 and ΔM F = 0 is shown in Fig. 1a and 1b. We applied the theoretically calculated distances of the Stark components from the absorption line of /CH 3/ 3CCl as function of the electric field strength as well as the relative intensities of the components in order to interpret our experimental results concerning the Stark effect.

  9. Crystal structures of three complexes of zinc chloride with tri-tert-butyl­phosphane

    PubMed Central

    Finke, Aaron D.; Gray, Danielle L.; Moore, Jeffrey S.

    2016-01-01

    Under anhydrous conditions and in the absence of a Lewis-base solvent, a zinc chloride complex with tri-tert-butyl­phosphane as the μ-bridged dimer is formed, viz. di-μ-chlorido-bis­[chlorido­bis­(tri-tert-butyl­phosphane)zinc], [ZnCl4(C12H27P)2], (1), which features a nearly square-shaped (ZnCl)2 cyclic core and whose Cl atoms inter­act weakly with C—H groups on the phosphane ligand. In the presence of THF, monomeric di­chlorido­(tetra­hydro­furan-κO)(tri-tert-butyl­phosphane-κP)zinc, [ZnCl2(C4H8O)(C12H27P)] or [P(tBu3)(THF)ZnCl2], (2), is formed. This slightly distorted tetra­hedral Zn complex has weak C—H⋯Cl inter­actions between the Cl atoms and phosphane and THF C—H groups. Under ambient conditions, the hydrolysed complex tri-tert-butyl­phospho­nium aqua­tri­chlorido­zincate 1,2-di­chloro­ethane monosolvate, (C12H28P)[ZnCl3(H2O)]·C2H4Cl2 or [HPtBu3]+ [(H2O)ZnCl3]−·C2H4Cl2, (3), is formed. This complex forms chains of [(H2O)ZnCl3]− anions from hydrogen-bonding inter­actions between the water H atoms and Cl atoms that propagate along the b axis. PMID:26870580

  10. Crystal structures of three complexes of zinc chloride with tri-tert-butyl-phosphane.

    PubMed

    Finke, Aaron D; Gray, Danielle L; Moore, Jeffrey S

    2016-01-01

    Under anhydrous conditions and in the absence of a Lewis-base solvent, a zinc chloride complex with tri-tert-butyl-phosphane as the μ-bridged dimer is formed, viz. di-μ-chlorido-bis-[chlorido-bis-(tri-tert-butyl-phosphane)zinc], [ZnCl4(C12H27P)2], (1), which features a nearly square-shaped (ZnCl)2 cyclic core and whose Cl atoms inter-act weakly with C-H groups on the phosphane ligand. In the presence of THF, monomeric di-chlorido-(tetra-hydro-furan-κO)(tri-tert-butyl-phosphane-κP)zinc, [ZnCl2(C4H8O)(C12H27P)] or [P(tBu3)(THF)ZnCl2], (2), is formed. This slightly distorted tetra-hedral Zn complex has weak C-H⋯Cl inter-actions between the Cl atoms and phosphane and THF C-H groups. Under ambient conditions, the hydrolysed complex tri-tert-butyl-phospho-nium aqua-tri-chlorido-zincate 1,2-di-chloro-ethane monosolvate, (C12H28P)[ZnCl3(H2O)]·C2H4Cl2 or [HPtBu3](+) [(H2O)ZnCl3](-)·C2H4Cl2, (3), is formed. This complex forms chains of [(H2O)ZnCl3](-) anions from hydrogen-bonding inter-actions between the water H atoms and Cl atoms that propagate along the b axis. PMID:26870580

  11. 40 CFR 721.10326 - 2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... ester, polymer with butyl 2-propenoate, ethyl 2-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2...-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2-propenoate (1:2), 2,2′-(1,2-diazenediyl)bis - and 2,2... butyl 2-propenoate, ethyl 2-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2-propenoate (1:2),...

  12. 40 CFR 721.10326 - 2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... ester, polymer with butyl 2-propenoate, ethyl 2-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2...-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2-propenoate (1:2), 2,2′-(1,2-diazenediyl)bis - and 2,2... butyl 2-propenoate, ethyl 2-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2-propenoate (1:2),...

  13. Alkylation of C60. Reaction between C60 anions and tert-butyl chloride and mass spectrometry analysis

    NASA Astrophysics Data System (ADS)

    Bourcier, S.; Chaurand, P.; Ciot, C.; Della-Negra, S.; Fabre, C.; Greugny, V.; Marx, L.; Rassat, A.; Rousseau, A.

    1996-11-01

    Alkylation of C60 in tetrahydrofuran with tert-butyl chloride and lithium gives a variety of products. Adducts of general formula C60Hn(t-Bu)qOx(thf)y (where t-Bu is the tert-butyl group and thf the tetrahydrofuryl group (C4H7O)) have been detected by mass spectrometry, with n <= 8, q + y <= 18 and x = 0, 1, 2 depending on experimental conditions. IR and NMR spectra of products confirm these assignments.

  14. Grafting densely-packed poly( n-butyl methacrylate) chains from an iron substrate by aryl diazonium surface-initiated ATRP: XPS monitoring

    NASA Astrophysics Data System (ADS)

    Matrab, Tarik; Save, Maud; Charleux, Bernadette; Pinson, Jean; Cabet-deliry, Eva; Adenier, Alain; Chehimi, Mohamed M.; Delamar, Michel

    2007-06-01

    Poly( n-butyl methacrylate), PBMA, chains were grafted by atom transfer radical polymerization (ATRP) from the surface of iron plates using electrochemically attached initiators based on diazonium salts providing an iron/polyphenylene/PBMA structure. This surface-initiated ATRP procedure was controlled by the addition of a small proportion of Cu ++ deactivator, but in the absence of any sacrificial initiator. Combined XPS, IR and AFM experiments provide a powerful means for the characterization of the obtained complex iron/polyphenylene/PBMA layered structure. It is possible to measure the thickness of the brominated aryl structure covalently attached to iron. Concerning the PBMA brushes, their presence on the surface was confirmed by IRRAS. The brominated chain end could be traced by XPS testifying for the ATRP character of the polymerization and the thickness of the polymer brushes was determined. The controlled living ATRP character of the polymerization is confirmed through a linear correlation between the thickness of the layer and the degree of polymerization. Measurement of the grafting density of PBMA chains indicates that they are compactly packed and that, approximately, one brominated aryl chain out of two efficiently initiates ATRP.

  15. Advanced analytical methods for the structure elucidation of polystyrene-b-poly(n-butyl acrylate) block copolymers prepared by reverse iodine transfer polymerisation.

    PubMed

    Wright, Trevor Gavin; Pfukwa, Helen; Pasch, Harald

    2015-09-10

    Reverse iodine transfer polymerisation (RITP) is a living radical polymerisation technique that has shown to be feasible in synthesising segmented styrene-acrylate copolymers. Polymers synthesised via RITP are typically only described regarding their bulk properties using nuclear magnetic resonance spectroscopy and size exclusion chromatography. To fully understand the complex composition of the polymerisation products and the RITP reaction mechanism, however, it is necessary to use a combination of advanced analytical methods. In the present RITP procedure, polystyrene was synthesised first and then used as a macroinitiator to synthesise polystyrene-block-poly(n-butyl acrylate) (PS-b-PBA) block copolymers. For the first time, these PS-b-PBA block copolymers were analysed by a combination of SEC, in situ(1)H NMR and HPLC. (1)H NMR was used to determine the copolymer composition and the end group functionality of the samples, while SEC and HPLC were used to confirm the formation of block copolymers. Detailed information on the living character of the RITP process was obtained. PMID:26388490

  16. Antioxidant activity and protective effect of extract of Celosia cristata L. flower on tert-butyl hydroperoxide-induced oxidative hepatotoxicity.

    PubMed

    Kim, Yon-Suk; Hwang, Jin-Woo; Sung, Si-Heung; Jeon, You-Jin; Jeong, Jae-Hyun; Jeon, Byong-Tae; Moon, Sang-Ho; Park, Pyo-Jam

    2015-02-01

    This study was undertaken to evaluate the antioxidant potential and protective effects of Celosia cristata L. (Family: Amaranthaceae) flower (CCF) extracts on tert-butyl-hydroperoxide (t-BHP)-induced oxidative damage in the hepatocytes of Chang cells and rat livers. In vitro, CCF extracts exhibited protective effect through their radical scavenging ability to enhance cell viability, prevent reactive oxygen species (ROS) generation, and inhibit mitochondrial membrane depolarisation in t-BHP-induced hepatotoxicity in Chang cells. In vivo, oral feeding of CCF (100mg and 500mg/kg of body weight) to rats for five consecutive days before a single dose of t-BHP (2mmol/kg, i.p.) showed a significant (p<0.05) protective effect by lowering serum levels of glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT). The extract decreased the hepatic levels of lipid peroxidation (MDA) and serum level of triglyceride (TG) against t-BHP-induced oxidative stress. These results indicate that CCF extract prevented oxidative stress-induced liver injury by enhancing hepatocyte antioxidant abilities. PMID:25172750

  17. tert-Butyl hydroperoxide-induced differing plasma membrane and oxidative stress processes in yeast strains BY4741 and erg5Δ.

    PubMed

    Gazdag, Zoltán; Máté, Gábor; Certik, Milan; Türmer, Katalin; Virág, Eszter; Pócsi, István; Pesti, Miklós

    2014-07-01

    The molecular mechanism of tert-butyl hydroperoxide (t-BuOOH) elicited cytotoxicity and the background of t-BuOOH sensitivity were studied in the Saccharomyces cerevisiae ergosterol-less gene deletion mutant erg5Δ and its parental strain BY4741. In comparison to BY4741, untreated erg5Δ cells exhibited alterations in sterol and fatty acid compositions of the plasma membrane, as reflected by the inherent amphotericin B resistance, an elevated level (31%) of plasma membrane rigidity and a decreased uptake of glycerol. Surprisingly, the untreated erg5Δ cells exhibited an unbalanced intracellular redox state, accompanied by the continuous upregulation of the antioxidant enzymes Mn superoxide dismutase, catalase, and glutathione S-transferase, which resulted in decreased specific concentrations of superoxide and peroxides and elevated levels of the hydroxyl radical and thiols. The 2.5-fold sensitivity of erg5Δ to t-BuOOH suggested that the oxidative stress adaptation processes of the mutant could not restore the redox homeostasis of the cells and there is an overlap between sterol and redox homeostases. t-BuOOH treatment of both strains induced adaptive modification of the sterol and fatty acid compositions, increased the plasma membrane fluidity and elevated the specific activities of most antioxidant enzymes through specific regulation processes in a strain-dependent manner. PMID:24687861

  18. Comparative study on thiol drugs' effect on tert-butyl hydroperoxide induced luminol chemiluminescence in human erythrocyte lysate and hemoglobin oxidation.

    PubMed

    Sajewicz, Waldemar; Zalewska, Marta; Milnerowicz, Halina

    2015-02-01

    The current studies have investigated the effect of heterocyclic drugs with the single thiol group (thiamazole, mercaptopurine) and dithiol aliphatic drugs (dimercaptosuccinic acid, dithiothreitol) under oxidative stress conditions, using tert-butyl hydroperoxide (t-BuOOH), in human erythrocyte lysate with the luminol-enhanced chemiluminescence technique. Knowing that oxidative processes induced by t-BuOOH are triggered by (oxy)hemoglobin (Hb), the effect of different thiol drugs (RSH) on isolated human Hb oxidation to methemoglobin (MHb) and hemichromes (HChr) was further considered. Three types of chemiluminescence curves, fitting to logistic-exponential model, have been revealed under influence of RSH. Structure of the data (MHb and HChr production, and free radical activity of RSH) in Principal Component Analysis visualization and kinetic profiles of chemiluminescence integrate information in terms of the diversity of RSH reaction mechanisms depending on the specific molecular context of the given thiol: aliphatic or aromatic nature as well as the number and position of the -SH groups in the molecule. The study conducted in presented in vitro systems indicates the potential role of thiol drugs mediated toxicity in an oxidative stress dependent mechanism. PMID:25308193

  19. Magnetorheological suspensions based on modified carbonyl iron particles with an extremely thin poly(n-butyl acrylate) layer and their enhanced stability properties

    NASA Astrophysics Data System (ADS)

    Mrlik, Miroslav; Pavlinek, Vladimir

    2016-08-01

    This study is focused on the modification of magnetic carbonyl iron (CI) particles with a thin polymer shell utilizing the atom-transfer radical polymerization (ATRP) technique, enabling control of the molecular weight and polydispersity of the final grafted polymer chains on the surface of CI particles and therefore also allowing tuning of the magnetorheological (MR) performance as well as stability properties (chemical, sedimentation). Hence, the bare CI particles were coated with a poly(butyl acrylate) (PBA) shell by the ATRP technique. The polymerization procedure of polymer grafting on the surface of the CI particles was characterized by gel permeation chromatography and nuclear magnetic resonance. The presence of the PBA chain on the CI particles was confirmed by Fourier infrared spectroscopy and energy dispersive spectroscopy. A saturation magnetization analysis using vibrating sample magnetometer proved that a thin polymer shell negligibly affects their magnetic properties, and data fit into the Jiles–Atherton model allowed the finite magnetization saturation for both bare CI and CI-PBA particles to be obtained. Furthermore, it was proved that a thin PBA coating provides sufficiently enhanced chemical and sedimentation stability properties for such a system, while the MR performance investigated using a rotational rheometer was affected negligibly. Finally it can be stated that a controllable coating performed via the ATRP technique is a useful tool to significantly improve stability properties, while the MR performance maintains values suitable for real-life applications.

  20. Intriguing Morphology Evolution from Noncrosslinked Poly(tert-butyl acrylate) Seeds with Polar Functional Groups in Soap-Free Emulsion Polymerization of Styrene.

    PubMed

    Wang, Lu; Pan, Mingwang; Song, Shaofeng; Zhu, Lei; Yuan, Jinfeng; Liu, Gang

    2016-08-01

    Herein, we demonstrate a facile approach to prepare anisotropic poly(tert-butyl acrylate)/polystyrene (PtBA/PS) composite particles with controllable morphologies by soap-free seeded emulsion polymerization (SSEP). In the first step, noncrosslinked PtBA seeds with self-stabilizing polar functional groups (e.g., ester groups and radicals) are synthesized by soap-free emulsion polymerization. During the subsequent SSEP of styrene (St), PS bulges are nucleated on the PtBA seeds due to the microphase separation confined in the latex particles. The morphology evolution of PtBA/PS composite particles is tailored by varying the monomer/seed feed ratio, polymerization time, and polymerization temperature. Many intriguing morphologies, including hamburger-like, litchi-like, mushroom-like, strawberry-like, bowl-like, and snowman-like, have been acquired for PtBA/PS composite particles. The polar groups on the PtBA seed surface greatly influence the formation and further merging of PS/St bulges during the polymerization. A possible formation mechanism is proposed on the basis of experimental results. These complex composite particles are promising for applications in superhydrophobic coatings. PMID:27389855

  1. Phenothiazines inhibit copper and endothelial cell-induced peroxidation of low density lipoprotein. A comparative study with probucol, butylated hydroxytoluene and vitamin E.

    PubMed

    Breugnot, C; Mazière, C; Salmon, S; Auclair, M; Santus, R; Morlière, P; Lenaers, A; Mazière, J C

    1990-11-01

    The effect of two phenothiazines, chlorpromazine (CPZ) and trifluoperazine (TFP) on the copper and endothelial cell-induced peroxidation of low density lipoprotein (LDL) has been studied and compared to that of drugs previously shown to protect LDL against peroxidation: probucol (PBC) and butylated hydroxytoluene (BHT). Incubation with CPZ or TFP inhibited in a dose-dependent manner LDL peroxidation induced either by copper ions or by cultured endothelial cells. Both the electrophoretic mobility and the thiobarbituric reactive substance content of LDL returned to almost normal values in the presence of 50 microM CPZ or TFP. The two studied phenothiazines also strongly inhibited the hydrolysis of LDL phosphatidylcholine which accompanies copper or endothelial cell-induced peroxidation of the particle. CPZ and TFP were as effective as PBC and BHT in inhibiting the LDL peroxidation. Whereas copper or endothelial cell-oxidized LDL were recognized and rapidly catabolized by mouse peritoneal macrophages, CPZ- or TFP-, as well as PBC- or BHT-treated LDL were not. Moreover, it was found that, in contrast to vitamin E, neither CPZ nor PBC reacted with model peroxy radicals formed by gamma irradiation of aerated ethanol. The possible mechanisms underlying this protective effect of phenothiazines against LDL oxidative modification are discussed. PMID:2242028

  2. Comparative cytotoxicity between butylated hydroxytoluene and its methylcarbamate derivative, terbucarb, on isolated rat hepatocytes

    SciTech Connect

    Nakagawa, Y.; Yaguchi, K.; Suzuki, T. )

    1994-08-01

    Butylated hydroxytoluene (3,5-di-tert-butyl-4-hydroxytoluene; BHT) is widely used as phenolic antioxidant in processed foods, cosmetics and petroleum products. It is well known that high doses of BHT cause acute hepatic damage accompanied by centrilobular necrosis in rats. The hepatic damage is associated with prolonged depletion of glutathione (GSH). Terbucarb (2,6-di-tert-butyl-para-tolyl-methylcarbamate), which has a methylcarbamate group substituted for the phenol group on BHT, was developed as an insecticide and is also presently used as a herbicide on turfgrass. Despite the metabolic and toxicological details known about BHT in vivo and in vitro, no extensive studies have been reported on the metabolism and toxicity of Terbucarb. The isolated hepatocyte system provides a very useful system for the study of the temporal sequences leading to cell damage caused by chemicals and drugs. Here, using freshly isolated rat hepatocytes, we report on the comparative toxic effects of BHT and its methylcarbamate derivative, Terbucarb. 17 refs., 2 figs., 2 tabs.

  3. Comprehensive testing to measure the response of butyl rubber to Hanford tank waste simulant

    SciTech Connect

    NIGREY,PAUL J.

    2000-05-01

    This report presents the findings of the Chemical Compatibility Program developed to evaluate plastic packaging components that may be incorporated in packaging mixed-waste forms for transportation. Consistent with the methodology outlined in this report, the authors performed the second phase of this experimental program to determine the effects of simulant Hanford tank mixed wastes on packaging seal materials. That effort involved the comprehensive testing of five plastic liner materials in an aqueous mixed-waste simulant. The testing protocol involved exposing the materials to {approximately}143, 286, 571, and 3,670 krad of gamma radiation and was followed by 7-, 14-, 28-, 180-day exposures to the waste simulant at 18, 50, and 60 C. Butyl rubber samples subjected to the same protocol were then evaluated by measuring seven material properties: specific gravity, dimensional changes, mass changes, hardness, compression set, vapor transport rates, and tensile properties. From the analyses, they determined that butyl rubber has relatively good resistance to radiation, this simulant, and a combination of these factors. These results suggest that butyl rubber is a relatively good seal material to withstand aqueous mixed wastes having similar composition to the one used in this study.

  4. Biodegradation of tert-butyl alcohol and related xenobiotics by a methylotrophic bacterial isolate.

    PubMed

    Piveteau, P; Fayolle, F; Vandecasteele, J P; Monot, F

    2001-04-01

    A new aerobic bacterial strain, CIP 1-2052, isolated from an activated sludge sample, was able to use tert-butyl alcohol (TBA), a product of methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE) degradation, as its sole carbon and energy source. Cobalt ions stimulated TBA mineralization. The maximum growth and TBA degradation rates were 0.032 +/- 0.004 h(-1) and 35.8 +/- 8.5 mg TBA x g(-1) (cell dry mass) per h, respectively. The growth yield on TBA was 0.54 +/- 0.02 g x g(-1). Strain CIP 1-2052 exhibited a particular substrate specificity towards alcohols. It degraded tertiary alcohols, TBA and tert-amyl alcohol (TAA), but neither their primary and secondary alcohol homologues, nor ethanol. However, one-carbon compounds, namely methanol and formate, were degraded by strain CIP 1-2052, showing the methylotrophic nature of this isolate. The properties of this new strain suggest that it could be used for bioremediation of contaminated aquifers. PMID:11341321

  5. Discovery and application of new bacterial strains for asymmetric synthesis of L-tert-butyl leucine in high enantioselectivity.

    PubMed

    Jin, Jian-Zhong; Chang, Dong-Liang; Zhang, Jie

    2011-06-01

    Discovery of new bacterial strains with fast identification in a miniaturized system was performed for the synthesis of optically active L-tert-butyl leucine. With tert-butyl leucine amide as nitrogen source, one bacterial strain with high conversion and high enantioselectivity was discovered among 120 isolated microorganisms from local soils and identified as Mycobacterium sp. JX009. Glucose and ammonium chloride were examined as the good carbon source and nitrogen source for the cells' growth separately. The cells grew better at 30 °C and at pH 7.5 with higher activity of 2,650 U/l in comparison with other conditions. Cells' stability was improved by immobilization on synthetic resin 0730 without pretreatment. Tert-butyl leucine amide (30 mM) was successfully hydrolyzed by immobilized cells and examined as the highest chemical concentration that cells could endure. After six reaction cycles, the immobilized cells retained 90% activity with production of L-tert-butyl leucine in 98% ee. The results firstly reported the application of new bacterial strain in the hydrolysis of tert-butyl leucine amide to produce optically active L-tert-butyl leucine in an efficient way with investigation in detail. PMID:21153891

  6. A Mechanochemical Switch to Control Radical Intermediates

    PubMed Central

    2015-01-01

    B12-dependent enzymes employ radical species with exceptional prowess to catalyze some of the most chemically challenging, thermodynamically unfavorable reactions. However, dealing with highly reactive intermediates is an extremely demanding task, requiring sophisticated control strategies to prevent unwanted side reactions. Using hybrid quantum mechanical/molecular mechanical simulations, we follow the full catalytic cycle of an AdoB12-dependent enzyme and present the details of a mechanism that utilizes a highly effective mechanochemical switch. When the switch is “off”, the 5′-deoxyadenosyl radical moiety is stabilized by releasing the internal strain of an enzyme-imposed conformation. Turning the switch “on,” the enzyme environment becomes the driving force to impose a distinct conformation of the 5′-deoxyadenosyl radical to avoid deleterious radical transfer. This mechanochemical switch illustrates the elaborate way in which enzymes attain selectivity of extremely chemically challenging reactions. PMID:24846280

  7. A mechanochemical switch to control radical intermediates.

    PubMed

    Brunk, Elizabeth; Kellett, Whitney F; Richards, Nigel G J; Rothlisberger, Ursula

    2014-06-17

    B₁₂-dependent enzymes employ radical species with exceptional prowess to catalyze some of the most chemically challenging, thermodynamically unfavorable reactions. However, dealing with highly reactive intermediates is an extremely demanding task, requiring sophisticated control strategies to prevent unwanted side reactions. Using hybrid quantum mechanical/molecular mechanical simulations, we follow the full catalytic cycle of an AdoB₁₂-dependent enzyme and present the details of a mechanism that utilizes a highly effective mechanochemical switch. When the switch is "off", the 5'-deoxyadenosyl radical moiety is stabilized by releasing the internal strain of an enzyme-imposed conformation. Turning the switch "on," the enzyme environment becomes the driving force to impose a distinct conformation of the 5'-deoxyadenosyl radical to avoid deleterious radical transfer. This mechanochemical switch illustrates the elaborate way in which enzymes attain selectivity of extremely chemically challenging reactions. PMID:24846280

  8. The Electronic Spectrum of the Fulvenallenyl Radical.

    PubMed

    Chakraborty, Arghya; Fulara, Jan; Maier, John P

    2016-01-01

    The fulvenallenyl radical was produced in 6 K neon matrices after mass-selective deposition of C7H5(-) and C7H5(+) generated from organic precursors in a hot cathode ion source. Absorption bands commencing at λ=401.3 nm were detected as a result of photodetachment of electrons from the deposited C7H5(-) and also by neutralization of C7H5(+) in the matrix. The absorption system is assigned to the 1 (2)B1 ←X (2)B1 transition of the fulvenallenyl radical on the basis of electronic excitation energies calculated with the MS-CASPT2 method. The vibrational excitation bands detected in the spectrum concur with the structure of the fulvenallenyl radical. Employing DFT calculations, it is found that the fulvenallenyl anion and its radical are the global minima on the potential energy surface among plausible structures of C7H5. PMID:26593635

  9. Fast beam studies of free radical photodissociation

    SciTech Connect

    Neumark, D.M.

    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.

  10. [Robotic laparoscopic radical prostatectomy: update 2008].

    PubMed

    John, H

    2008-03-01

    Radical prostatectomy aims for optimal tumor control, minimal morbidity, and best functional outcomes of urinary continence and erection. With the introduction of the robotic daVinci surgical system an impressive shift from open radical to robotic laparoscopic prostatectomy (RLP) has occurred especially in the USA. Unfortunately, initial and instrumental costs and maintenance fees of the system are still very high. Compared with the open retropubic approach, RLP has a similar short-term outcome in oncological control, potency, and urinary continence but potentially distinctly favorable benefits in blood loss, transfusion rates, and minor complications. However, RLP is still in its infancy compared to open radical prostatectomy. Inter-institutional trials with the same validated questionnaires are necessary for the future to evaluate oncological and functional results conclusively. The individual surgeon's experience with his routinely preferred technique remains the crucial key for a successful oncological and functional outcome in radical prostatectomy, whatever technology is used. PMID:18231769

  11. HETEROGENOUS PHOTOREACTION OF FORMALDEHYDE WITH HYDROXYL RADICALS

    EPA Science Inventory

    Atmospheric heterogeneous photoreactions occur between formaldehyde and hydroxyl radicals to produce formic acid. hese photoreactions not only occur in clouds, but also in other tropospheric hydrometeors such as precipitation and dew droplets. xperiments were performed by irradia...

  12. [Pulmonary toxicity of free radicals of oxygen].

    PubMed

    Housset, B; Junod, A

    1983-01-01

    Free oxygen radicals result from aerobic cellular metabolism; their toxicity is prevented by immediate degradation due to an endless variety of biochemical systems. The nature of these radicals, their cellular production as well as the defence mechanism which oppose their toxic effects are successively and briefly analysed. The potential role of these radicals in the genesis of different lung diseases is still poorly understood. However, certain toxic agents (oxygen, gas pollutants, ionising radiation, toxic products) can act as a whole or at least in part by their intermediaries. The experimental arguments in favour of this hypothesis are reviewed in passing. If the relative importance of the toxic mechanism is still imprecise, free radicals are certainly implicated in pulmonary disease and constitute a new aspect of respiratory patho-physiology. PMID:6189156

  13. Innovation Type, Radicalness, and the Adoption Process.

    ERIC Educational Resources Information Center

    Damanpour, Fariborz

    1988-01-01

    Reviews studies on the impact of organizational factors on the adoption of innovations along three dimensions (innovation type, innovation radicalness, and stages of adoption), finding considerable agreement. Proposes a research agenda for future studies. (SR)

  14. RADICALLY CONTESTED ASSERTIONS IN ECOSYSTEM MANAGEMENT

    EPA Science Inventory

    Ecosystem management is a magnet for controversy, in part because some of its formulations rest on questionable assertions that are radically contested. These assertions are important to understanding much of the conflict surrounding ecosystem management and, therrefore, deserve...

  15. Catalytic Radical Domino Reactions in Organic Synthesis

    PubMed Central

    Sebren, Leanne J.; Devery, James J.; Stephenson, Corey R.J.

    2014-01-01

    Catalytic radical-based domino reactions represent important advances in synthetic organic chemistry. Their development benefits synthesis by providing atom- and step-economical methods to complex molecules. Intricate combinations of radical, cationic, anionic, oxidative/reductive, and transition metal mechanistic steps result in cyclizations, additions, fragmentations, ring-expansions, and rearrangements. This Perspective summarizes recent developments in the field of catalytic domino processes. PMID:24587964

  16. Regioselective Radical Arylation of 3-Hydroxypyridines.

    PubMed

    Fürst, Michael C D; Bock, Leonard R; Heinrich, Markus R

    2016-07-01

    The titanium(III)-mediated radical arylation of 3-hydroxypyridines was found to proceed with high regioselectivity for the 2-position. Using aryldiazonium chlorides, which were prepared from the corresponding anilines, as aryl radical sources, a range of 3-hydroxy-2-phenylpyridines were obtained in moderate to good yields under simple reaction conditions. Reactions of ortho-carboxylic ester substituted phenyldiazonium salts directly provided tricyclic benzopyranopyridinones. PMID:27258367

  17. The stabilization energies of polyenyl radicals

    NASA Astrophysics Data System (ADS)

    Luo, Yu-Ran; Holmes, John L.

    1994-10-01

    The resonance stabilization energies, Es, of polyenyl radicals can be estimated by the equation Es( N)=-13.2+[3.95-15.8(2) -2/ n] kcal mol -1, where N is the number of C, C-π bonds in the polyenyl radicals. This correlation has been extended for predicting the weakest HC, CC and COH bond dissociation energies in vitamin A and similar compounds.

  18. Thermodynamic properties and ideal-gas enthalpies of formation for butyl vinyl ether, 1,2-dimethoxyethane, methyl glycolate, bicyclo[2.2.1]hept-2-ene, 5-vinylbicyclo[2.2.1]hept-2-ene, trans-azobenzene, butyl acrylate, di-tert-butyl ether, and hexane-1,6-diol

    SciTech Connect

    Steele, W.V.; Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A.; Smith, N.K.

    1996-11-01

    Ideal-gas enthalpies of formation of butyl vinyl ether, 1,2-dimethoxyethane, methyl glycolate, bicyclo-[2.2.1]hept-2-ene, 5-vinylbicyclo[2.2.1]hept-2-ene, trans-azobenzene, butyl acrylate, di-tert-butyl ether, and hexane-1,6-diol are reported. Enthalpies of fusion were determined for bicyclo[2.2.1]hept-2-ene and trans-azobenzene. Two-phase (solid + vapor) or (liquid + vapor) heat capacities were determined from 300 K to the critical region or earlier decomposition temperature for each compound studied. Liquid-phase densities along the saturation line were measured for bicyclo[2.2.1]hept-2-ene. For butyl vinyl ether and 1,2-dimethoxyethane, critical temperatures and critical densities were determined from the dsc results and corresponding critical pressures derived from the fitting procedures. Fitting procedures were used to derive critical temperatures, critical pressures, and critical densities for bicyclo[2.2.1]hept-2-ene, 5-vinylbicyclo[2.2.1]hept-2-ene, trans-azobenzene, butyl acrylate, and di-tert-butyl ether. Group-additivity parameters or ring-correction terms useful in the application of the Benson group-contribution correlations were derived.

  19. Inactivation of Bacillus atrophaeus by OH radicals

    NASA Astrophysics Data System (ADS)

    Ono, Ryo; Yonetamari, Kenta; Tokumitsu, Yusuke; Yonemori, Seiya; Yasuda, Hachiro; Mizuno, Akira

    2016-08-01

    The inactivation of Bacillus atrophaeus by OH radicals is measured. This study aims to evaluate the bactericidal effects of OH radicals produced by atmospheric-pressure nonthermal plasma widely used for plasma medicine; however, in this study, OH radicals are produced by vacuum ultraviolet (VUV) photolysis of water vapor instead of plasma to allow the production of OH radicals with almost no other reactive species. A 172 nm VUV light from a Xe2 excimer lamp irradiates a He–H2O mixture flowing in a quartz tube to photodissociate H2O to produce OH, H, O, HO2, H2O2, and O3. The produced reactive oxygen species (ROS) flow out of the quartz tube nozzle to the bacteria on an agar plate and cause inactivation. The inactivation by OH radicals among the six ROS is observed by properly setting the experimental conditions with the help of simulations calculating the ROS densities. A 30 s treatment with approximately 0.1 ppm OH radicals causes visible inactivation.

  20. Hydroxyl radical oxidation of feruloylated arabinoxylan.

    PubMed

    Bagdi, Attila; Tömösközi, Sándor; Nyström, Laura

    2016-11-01

    Feruloylated arabinoxylan (AX) has a unique capacity to form covalent gels in the presence of certain oxidizing agents. The present study demonstrates that hydroxyl radical oxidation does not provoke ferulic acid dimerization and thus oxidative gelation. We studied the hydroxyl radical mediated oxidation of an alkali-extracted AX preparation (purity: 92g/100g dry matter) that showed gel-forming capability upon peroxidase/hydrogen peroxide treatment. Hydroxyl radicals were produced with ascorbate-driven Fenton reaction and the radical formation was monitored with electron paramagnetic resonance, using a POBN/EtOH spin trapping system. Oxidation was carried out at different catalytic concentrations of iron (50 and 100μM) and at different temperatures (20°C, 50°C, and 80°C). It was demonstrated that hydroxyl radical oxidation does not provoke gel formation, but viscosity decrease in AX solution, which suggests polymer degradation. Furthermore, it was demonstrated that hydroxyl radical formation in AX solution can be initiated merely by increasing temperature. PMID:27516272

  1. Selective Radical-Radical Cross-Couplings: Design of a Formal β-Mannich Reaction.

    PubMed

    Jeffrey, Jenna L; Petronijević, Filip R; MacMillan, David W C

    2015-07-01

    A direct β-coupling of cyclic ketones with imines has been accomplished via the synergistic combination of photoredox catalysis and organocatalysis. Transient β-enaminyl radicals derived from ketones via enamine and oxidative photoredox catalysis readily combine with persistent α-amino radicals in a highly selective hetero radical-radical coupling. This novel pathway to γ-aminoketones is predicated upon the use of DABCO as both a base and an electron transfer agent. This protocol also formally allows for the direct synthesis of β-Mannich products via a chemoselective three-component coupling of aryl aldehydes, amines, and ketones. PMID:26075347

  2. Practicing Radical Pedagogy: Balancing Ideals with Institutional Constraints.

    ERIC Educational Resources Information Center

    Sweet, Stephen

    1998-01-01

    Describes radical pedagogy and observes that an overview of "Teaching Sociology" suggests that few teachers fully practice it. Argues that while professors are free to teach radical theory, radical pedagogy is hindered by institutional constraints. Concludes that radical teachers may benefit from remaining more within the confines imposed by their…

  3. Evaluating UV/H2O2 processes for methyl tert-butyl ether and tertiary butyl alcohol removal: effect of pretreatment options and light sources.

    PubMed

    Li, Ke; Hokanson, David R; Crittenden, John C; Trussell, Rhodes R; Minakata, Daisuke

    2008-12-01

    In this paper, we evaluate the efficiency of UV/H2O2 process to remove methyl tert-butyl ether (MtBE) and tertiary butyl alcohol (tBA) from a drinking water source. Kinetic models were used to evaluate the removal efficiency of the UV/H2O2 technologies with different pretreatment options and light sources. Two commercial UV light sources, i.e. low pressure, high intensity lamps and medium pressure, high intensity lamps, were evaluated. The following pretreatment alternatives were evaluated: (1) ion exchange softening with seawater regeneration (NaIX); (2) Pellet Softening; (3) weak acid ion exchange (WAIX); and (4) high pH lime softening followed by reverse osmosis (RO). The presence or absence of a dealkalization step prior to the UV/H2O2 Advanced Oxidation Process (AOP) was also evaluated for each pretreatment possibility. Pretreatment has a significant impact on the performance of UV/H2O2 process. The NaIX with dealkalization was shown to be the most cost effective. The electrical energy per order (EEO) values for MtBE and tBA using low pressure high output UV lamps (LPUV) and 10mg/LH2O2 are 0.77 and 3.0 kWh/kgal-order, or 0.20 and 0.79 kWh/m3-order, respectively. For medium pressure UV high output lamps (MPUV), EEO values for MtBE and tBA are 4.6 and 15 kWh/kgal-order, or 1.2 and 4.0 kWh/m3-order, for the same H2O2 dosage. PMID:18951605

  4. Synthesis, structural characterization, electronic spectroscopy, and microfluidic detection of Cu+2 and UO2+2 [di-tert-butyl-salphenazine] complexes†

    PubMed Central

    Maynard, B. A.; Brooks, J. C.; Hardy, E. E.; Easley, C. J.; Gorden, A. E. V.

    2015-01-01

    Metal templation by condensation of 2,3-diaminophenazine with 3,5-di-tert-butyl-2-hydroxybenzaldehyde around the metal centers [M = Cu(ii), and UO2(vi)] affords a new class of M[di-tert-butyl sal-phenazine] metal complexes. Reported here is the synthesis, single crystal X-ray structural characterization, electronic spectroscopy, and microfluidic detection of the formation of these M[di-tert-butyl sal-phenazine] complexes. PMID:25657039

  5. Butyl acetate and yeasts interact in adhesion and germination of Botrytis cinerea conidia in vitro and in fungal decay of golden delicious apple.

    PubMed

    Filonow, A B

    2001-04-01

    Butyl acetate is a volatile aroma and flavor compound in apple. Conidia of three strains of Botrytis cinerea, a fungus that causes decay of apple fruit in postharvest storage, had greater adhesion to and greater germination on polycarbonate membrane filters on water inside sealed 500 cc glass jars that were injected with 4 microliters butyl acetate than conidia not so exposed. Conidial germination was highly correlated with conidial adhesion. The yeasts Sporobolomyces roseus and Cryptococcus laurentii, but not Saccharomyces cerevisiae, reduced the adhesion and germination promoting effect of butyl acetate. Conidia did not readily utilize butyl acetate as a food source, as shown by lack of tetrazolium violet reduction, whereas S. roseus and C. laurentii, but not S. cerevisiae did. Butyl acetate added to suspensions of conidia increased the electrical conductivity of the suspensions and increased the loss of 14C from 14C-labeled conidia compared to conidia unexposed to butyl acetate. Uptake of [14C]glucose by conidia was not increased by butyl acetate. Wounds of Golden Delicious apples inoculated with conidia (strain F-J-4) in a dilute solution of butyl acetate had greater decay than unexposed wounds. S. roseus and C. laurentii, but not S. cerevisiae, added with the conidia decreased the incidence or size of decay. Results indicated that butyl acetate increased conidial adhesion, stimulating conidial germination, and some yeasts can reduce this effect. PMID:11446303

  6. Substrate radical intermediates in soluble methane monooxygenase

    SciTech Connect

    Liu Aimin; Jin Yi; Zhang Jingyan; Brazeau, Brian J.; Lipscomb, John D. . E-mail: lipsc001@umn.edu

    2005-12-09

    EPR spin-trapping experiments were carried out using the three-component soluble methane monooxygenase (MMO). Spin-traps 5,5-dimethyl-1-pyrroline N-oxide (DMPO), {alpha}-4-pyridyl-1-oxide N-tert-butylnitrone (POBN), and nitrosobenzene (NOB) were used to investigate the possible formation of substrate radical intermediates during catalysis. In contrast to a previous report, the NADH-coupled oxidations of various substrates did not produce any trapped radical species when DMPO or POBN was present. However, radicals were detected by these traps when only the MMO reductase component and NADH were present. DMPO and POBN were found to be weak inhibitors of the MMO reaction. In contrast, NOB is a strong inhibitor for the MMO-catalyzed nitrobenzene oxidation reaction. When NOB was used as a spin-trap in the complete MMO system with or without substrate, EPR signals from an NOB radical were detected. We propose that a molecule of NOB acts simultaneously as a substrate and a spin-trap for MMO, yielding the long-lived radical and supporting a stepwise mechanism for MMO.

  7. Electrochemistry and spectroelectrochemistry of nitroxyl free radicals

    SciTech Connect

    Fish, J.R.; Swarts, S.G.; Sevilla, M.D.; Malinski, T.

    1988-06-30

    This work reports electrochemical and spectroelectrochemical studies of the two nitroxyl radicals 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) and 3-carbamoyl-2,2,5,5-tetramethyl-3-pyrrolin-1-yloxy (3-carbamoyl-PROXYL). Oxidation and reduction reactions have been observed in aqueous media over the pH range 2-12 in the potential range -0.8 to +0.8 V by differential pulse voltammetry, cyclic voltammetry, and thin-layer UV-visible spectroelectrochemistry, and the reaction products have been characterized by IR, NMR, and ESR spectrometry. At pH values less than 10, characteristic electrochemical behavior is observed to be analogous for both radicals, and the products from electron transfer compare quite favorably with those found by pulse radiolysis of aqueous solutions of nitroxyl radicals. At pH 2-9, a stable cation from a reversible oxidation and hydroxylamine following an irreversible reduction, as well as hydroxylated cation at pH higher than 9, are the same as those obtained in pulse radiolysis experiments. Spectroscopic evidence indicates that behavior following reduction at high pH differs for the two radicals. At pH 12, reduced TEMPO may undergo structural changes leading to the formation of a new radical consisting of a seven-membered ring.

  8. Radical-pair based avian magnetoreception

    NASA Astrophysics Data System (ADS)

    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.

  9. Modeling Radicalization Phenomena in Heterogeneous Populations.

    PubMed

    Galam, Serge; Javarone, Marco Alberto

    2016-01-01

    The phenomenon of radicalization is investigated within a mixed population composed of core and sensitive subpopulations. The latest includes first to third generation immigrants. Respective ways of life may be partially incompatible. In case of a conflict core agents behave as inflexible about the issue. In contrast, sensitive agents can decide either to live peacefully adjusting their way of life to the core one, or to oppose it with eventually joining violent activities. The interplay dynamics between peaceful and opponent sensitive agents is driven by pairwise interactions. These interactions occur both within the sensitive population and by mixing with core agents. The update process is monitored using a Lotka-Volterra-like Ordinary Differential Equation. Given an initial tiny minority of opponents that coexist with both inflexible and peaceful agents, we investigate implications on the emergence of radicalization. Opponents try to turn peaceful agents to opponents driving radicalization. However, inflexible core agents may step in to bring back opponents to a peaceful choice thus weakening the phenomenon. The required minimum individual core involvement to actually curb radicalization is calculated. It is found to be a function of both the majority or minority status of the sensitive subpopulation with respect to the core subpopulation and the degree of activeness of opponents. The results highlight the instrumental role core agents can have to hinder radicalization within the sensitive subpopulation. Some hints are outlined to favor novel public policies towards social integration. PMID:27166677

  10. Modeling Radicalization Phenomena in Heterogeneous Populations

    PubMed Central

    2016-01-01

    The phenomenon of radicalization is investigated within a mixed population composed of core and sensitive subpopulations. The latest includes first to third generation immigrants. Respective ways of life may be partially incompatible. In case of a conflict core agents behave as inflexible about the issue. In contrast, sensitive agents can decide either to live peacefully adjusting their way of life to the core one, or to oppose it with eventually joining violent activities. The interplay dynamics between peaceful and opponent sensitive agents is driven by pairwise interactions. These interactions occur both within the sensitive population and by mixing with core agents. The update process is monitored using a Lotka-Volterra-like Ordinary Differential Equation. Given an initial tiny minority of opponents that coexist with both inflexible and peaceful agents, we investigate implications on the emergence of radicalization. Opponents try to turn peaceful agents to opponents driving radicalization. However, inflexible core agents may step in to bring back opponents to a peaceful choice thus weakening the phenomenon. The required minimum individual core involvement to actually curb radicalization is calculated. It is found to be a function of both the majority or minority status of the sensitive subpopulation with respect to the core subpopulation and the degree of activeness of opponents. The results highlight the instrumental role core agents can have to hinder radicalization within the sensitive subpopulation. Some hints are outlined to favor novel public policies towards social integration. PMID:27166677

  11. Tuning the Reactivity of Radical through a Triplet Diradical Cu(II) Intermediate in Radical Oxidative Cross-Coupling

    PubMed Central

    Zhou, Liangliang; Yi, Hong; Zhu, Lei; Qi, Xiaotian; Jiang, Hanpeng; Liu, Chao; Feng, Yuqi; Lan, Yu; Lei, Aiwen

    2015-01-01

    Highly selective radical/radical cross-coupling is paid more attention in bond formations. However, due to their intrinsic active properties, radical species are apt to achieve homo-coupling instead of cross-coupling, which makes the selective cross-coupling as a great challenge and almost untouched. Herein a notable strategy to accomplish direct radical/radical oxidative cross-coupling has been demonstrated, that is metal tuning a transient radical to a persistent radical intermediate followed by coupling with another transient radical. Here, a transient nitrogen-centered radical is tuned to a persistent radical complex by copper catalyst, followed by coupling with a transient allylic carbon-centered radical. Firstly, nitrogen-centered radical generated from N-methoxybenzamide stabilized by copper catalyst was successfully observed by EPR. Then DFT calculations revealed that a triplet diradical Cu(II) complex formed from the chelation N-methoxybenzamide nitrogen-centered radical to Cu(II) is a persistent radical species. Moreover, conceivable nitrogen-centered radical Cu(II) complex was observed by high-resolution electrospray ionization mass spectrometry (ESI-MS). Ultimately, various allylic amides derivatives were obtained in good yields by adopting this strategy, which might inspire a novel and promising landscape in radical chemistry. PMID:26525888

  12. Tuning the Reactivity of Radical through a Triplet Diradical Cu(II) Intermediate in Radical Oxidative Cross-Coupling

    NASA Astrophysics Data System (ADS)

    Zhou, Liangliang; Yi, Hong; Zhu, Lei; Qi, Xiaotian; Jiang, Hanpeng; Liu, Chao; Feng, Yuqi; Lan, Yu; Lei, Aiwen

    2015-11-01

    Highly selective radical/radical cross-coupling is paid more attention in bond formations. However, due to their intrinsic active properties, radical species are apt to achieve homo-coupling instead of cross-coupling, which makes the selective cross-coupling as a great challenge and almost untouched. Herein a notable strategy to accomplish direct radical/radical oxidative cross-coupling has been demonstrated, that is metal tuning a transient radical to a persistent radical intermediate followed by coupling with another transient radical. Here, a transient nitrogen-centered radical is tuned to a persistent radical complex by copper catalyst, followed by coupling with a transient allylic carbon-centered radical. Firstly, nitrogen-centered radical generated from N-methoxybenzamide stabilized by copper catalyst was successfully observed by EPR. Then DFT calculations revealed that a triplet diradical Cu(II) complex formed from the chelation N-methoxybenzamide nitrogen-centered radical to Cu(II) is a persistent radical species. Moreover, conceivable nitrogen-centered radical Cu(II) complex was observed by high-resolution electrospray ionization mass spectrometry (ESI-MS). Ultimately, various allylic amides derivatives were obtained in good yields by adopting this strategy, which might inspire a novel and promising landscape in radical chemistry.

  13. Tuning the Reactivity of Radical through a Triplet Diradical Cu(II) Intermediate in Radical Oxidative Cross-Coupling.

    PubMed

    Zhou, Liangliang; Yi, Hong; Zhu, Lei; Qi, Xiaotian; Jiang, Hanpeng; Liu, Chao; Feng, Yuqi; Lan, Yu; Lei, Aiwen

    2015-01-01

    Highly selective radical/radical cross-coupling is paid more attention in bond formations. However, due to their intrinsic active properties, radical species are apt to achieve homo-coupling instead of cross-coupling, which makes the selective cross-coupling as a great challenge and almost untouched. Herein a notable strategy to accomplish direct radical/radical oxidative cross-coupling has been demonstrated, that is metal tuning a transient radical to a persistent radical intermediate followed by coupling with another transient radical. Here, a transient nitrogen-centered radical is tuned to a persistent radical complex by copper catalyst, followed by coupling with a transient allylic carbon-centered radical. Firstly, nitrogen-centered radical generated from N-methoxybenzamide stabilized by copper catalyst was successfully observed by EPR. Then DFT calculations revealed that a triplet diradical Cu(II) complex formed from the chelation N-methoxybenzamide nitrogen-centered radical to Cu(II) is a persistent radical species. Moreover, conceivable nitrogen-centered radical Cu(II) complex was observed by high-resolution electrospray ionization mass spectrometry (ESI-MS). Ultimately, various allylic amides derivatives were obtained in good yields by adopting this strategy, which might inspire a novel and promising landscape in radical chemistry. PMID:26525888

  14. Isolation of Hypervalent Group-16 Radicals and Their Application in Organic-Radical Batteries.

    PubMed

    Imada, Yasuyuki; Nakano, Hideyuki; Furukawa, Ko; Kishi, Ryohei; Nakano, Masayoshi; Maruyama, Hitoshi; Nakamoto, Masaaki; Sekiguchi, Akira; Ogawa, Masahiro; Ohta, Toshiaki; Yamamoto, Yohsuke

    2016-01-20

    Using a newly prepared tridentate ligand, we isolated hypervalent sulfur and selenium radicals for the first time and characterized their structures. X-ray crystallography, electron spin resonance spectroscopy, and density functional theory calculations revealed a three-coordinate hypervalent structure. Utilizing the reversible redox reactions between hypervalent radicals and the corresponding anions bearing Li(+), we developed organic radical batteries with these compounds as cathode-active materials. Furthermore, an all-radical battery, with these compounds as the cathode and a silyl radical as the anode, was developed that exhibited a practical discharge potential of ∼ 1.8 V and stable cycle performance, demonstrating the potential of these materials for use in metal-free batteries that can replace conventional Li-ion batteries where Li is used in the metal form. PMID:26721786

  15. Hydroxyl Radical Generation from Environmentally Persistent Free Radicals (EPFRs) in PM2.5

    PubMed Central

    Gehling, William; Khachatryan, Lavrent; Dellinger, Barry

    2015-01-01

    Hydroxyl radicals were generated from an aqueous suspension of ambient PM2.5 and detected utilizing 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a spin trap coupled with electron paramagnetic resonance (EPR) spectroscopy. Results from this study suggested the importance of environmentally persistent free radicals (EPFRs) in PM2.5 to generate significant levels of ·OH without the addition of H2O2. Particles for which the EPFRs were allowed to decay over time induced less hydroxyl radical. Additionally, higher particle concentrations produced more hydroxyl radical. Some samples did not alter hydroxyl radical generation when the solution was purged by air. This is ascribed to internal, rather than external surface associated EPFRs. PMID:24004313

  16. Forensic analysis of tertiary-butyl alcohol (TBA) detections in a hydrocarbon-rich groundwater basin.

    PubMed

    Quast, Konrad W; Levine, Audrey D; Kester, Janet E; Fordham, Carolyn L

    2016-04-01

    Tertiary-butyl alcohol (TBA), a high-production volume (HPV) chemical, was sporadically detected in groundwater and coalbed methane (CBM) wells in southeastern Colorado's hydrocarbon-rich Raton Basin. TBA concentrations in shallow water wells averaged 75.1 μg/L, while detections in deeper CBM wells averaged 14.4 μg/L. The detection of TBA prompted a forensic investigation to try to identify potential sources. Historic and recent data were reviewed to determine if there was a discernable pattern of TBA occurrence. Supplemental samples from domestic water wells, monitor wells, CBM wells, surface waters, and hydraulic fracturing (HF) fluids were analyzed for TBA in conjunction with methyl tertiary-butyl ether (MTBE) and ethyl tertiary-butyl ether (ETBE), proxies for evidence of contamination from reformulated gasoline or associated oxygenates. Exploratory microbiological sampling was conducted to determine if methanotrophic organisms co-occurred with TBA in individual wells. Meaningful comparisons of historic TBA data were limited due to widely varying reporting limits. Mapping of TBA occurrence did not reveal any spatial patterns or physical associations with CBM operations or contamination plumes. Additionally, TBA was not detected in HF fluids or surface water samples. Given the widespread use of TBA in industrial and consumer products, including water well completion materials, it is likely that multiple diffuse sources exist. Exploratory data on stable isotopes, dissolved gases, and microbial profiling provide preliminary evidence that methanotrophic activity may be producing TBA from naturally occurring isobutane. Reported TBA concentrations were significantly below a conservative risk-based drinking water screening level of 8000 μg/L derived from animal toxicity data. PMID:26946495

  17. n-Alkane assimilation and tert-butyl alcohol (TBA) oxidation capacity in Mycobacterium austroafricanum strains.

    PubMed

    Lopes Ferreira, Nicolas; Mathis, Hugues; Labbé, Diane; Monot, Frédéric; Greer, Charles W; Fayolle-Guichard, Françoise

    2007-06-01

    Mycobacterium austroafricanum IFP 2012, which grows on methyl tert-butyl ether (MTBE) and on tert-butyl alcohol (TBA), the main intermediate of MTBE degradation, also grows on a broad range of n-alkanes (C2 to C16). A single alkB gene copy, encoding a non-heme alkane monooxygenase, was partially amplified from the genome of this bacterium. Its expression was induced after growth on n-propane, n-hexane, n-hexadecane and on TBA but not after growth on LB. The capacity of other fast-growing mycobacteria to grow on n-alkanes (C1 to C16) and to degrade TBA after growth on n-alkanes was compared to that of M. austroafricanum IFP 2012. We studied M. austroafricanum IFP 2012 and IFP 2015 able to grow on MTBE, M. austroafricanum IFP 2173 able to grow on isooctane, Mycobacterium sp. IFP 2009 able to grow on ethyl tert-butyl ether (ETBE), M. vaccae JOB5 (M. austroaafricanum ATCC 29678) able to degrade MTBE and TBA and M. smegmatis mc2 155 with no known degradation capacity towards fuel oxygenates. The M. austroafricanum strains grew on a broad range of n-alkanes and three were able to degrade TBA after growth on propane, hexane and hexadecane. An alkB gene was partially amplified from the genome of all mycobacteria and a sequence comparison demonstrated a close relationship among the M. austroafricanum strains. This is the first report suggesting the involvement of an alkane hydroxylase in TBA oxidation, a key step during MTBE metabolism. PMID:17347817

  18. Molecular Dynamics of Tert-butyl Chloride Confined to CPG (7.4, 15.6 nm)

    NASA Astrophysics Data System (ADS)

    Szutkowska, L.; Peplińska, B.; Jurga, S.

    2006-08-01

    The paper complements our earlier NMR investigation of molecular dynamics of tert-butyl chloride restricted by geometries of the type MCM-41 and CPG by the new sizes of CPG and by differential scanning calorimetry method. We report proton and deuteron NMR lineshapes and the spin-lattice relaxation results of tert-butyl chloride in CPG of the 15.6 nm and 7.4 nm pore diameter in the temperature range 70 K ≤ T ≤ 292 K. The bulk-like component of the confined tert-butyl chloride, in temperatures corresponding to phase III, is interpreted as a composition of two dynamically different subphases. The parameters of motions of both subphases are derived. The tert-butyl group motion in both subphases is more restricted than in the bulk tert-butyl chloride, although the activation energies are lower. Differential scanning calorimetry was used to determine temperatures of the phase transitions (140 K ≤T ≤292 K). The results show that the depression of the phase transition temperature is pore size dependent and that the confinement has less influence on transition to the plastic phase than on the freezing and on the solid II - solid III transition.

  19. Determination of antagonism between cyhalofop-butyl and other rice (Oryza sativa) herbicides in barnyardgrass (Echinochloa crus-galli).

    PubMed

    Ottis, Brian V; Mattice, John D; Talbert, Ronald E

    2005-05-18

    Herbicide antagonism is defined as the reduction of control of certain weeds as the result of applying mixtures of two or more herbicides. Cyhalofop-butyl, a graminicide used for postemergence grass weed control in rice, is antagonized by some rice herbicides when applied simultaneously. The result of this type of antagonism usually results in decreased control of grass weeds. Research has shown that herbicide antagonism between graminicides and other herbicides may be caused by different mechanisms as the result of activity of the tank-mix partner. Using HPLC, the objective of this experiment was to analyze the fate of cyhalofop-butyl in barnyardgrass tissue when applied alone and in combination with halosulfuron, propanil, or triclopyr. Results indicated that absorption of cyhalofop-butyl and hydrolysis to its phytotoxic metabolite, cyhalofop-acid, was rapid and that halosulfuron and triclopyr had no effect. Because of a likely interaction of propanil with an apoplastic esterase enzyme, increased levels of cyhalofop-butyl and cyhalofop-acid were detected in barnyardgrass tissue, indicating that cyhalofop-butyl metabolism was hindered by propanil. PMID:15884840

  20. Electrochemical properties of the solvent SbCl/sub 3/-AlCl/sub 3/-N-(1-Butyl)Pyridinium chloride and electrochemical and spectroelectrochemical studies of arene solutes

    SciTech Connect

    Chapman, D.M.; Smith, G.P.; Soerlie, M.; Petrovic, C.; Mamantov, G.

    1984-07-01

    Physical and electrochemical properties are reported for SbCl/sub 3/-AlCl/sub 3/-N-(1-butyl)pyridinium chloride (BPCl) mixtures that are liquid at ambient temperatures; and studies of the electrogeneration and open-circuit decay of some arene radical cations, both in this medium and in SbCl/sub 3/-KCl at elevated temperatures, are described. Specific conductivities, densities, and viscosities of various compositions of SbCl/sub 3/-AlCl/sub 3/-BPCl were measured over the temperature range 24-100/sup 0/C. For a potentiometric titration between the compositions 60:18:22 and 60:22:18 with SbCl/sub 3/ fixed at 60 mole %, the potential of the Sb(III)/Sb(O) couple increased about 0.43V at 27/sup 0/C. The persistence of a series of different arene radical cations in SbCl/sub 3/-BP(AlCl)/sub 4/ is compared with their persistance in molten SbCl/sub 3/-KCl.

  1. Amyloid beta peptides do not form peptide-derived free radicals spontaneously, but can enhance metal-catalyzed oxidation of hydroxylamines to nitroxides.

    PubMed

    Dikalov, S I; Vitek, M P; Maples, K R; Mason, R P

    1999-04-01

    Amyloid beta (Abeta) peptides play an important role in the pathogenesis of Alzheimer's disease. Free radical generation by Abeta peptides was suggested to be a key mechanism of their neurotoxicity. Reports that neurotoxic free radicals derived from Abeta-(1-40) and Abeta-(25-35) peptides react with the spin trap N-tert-butyl-alpha-phenylnitrone (PBN) to form a PBN/.Abeta peptide radical adduct with a specific triplet ESR signal assert that the peptide itself was the source of free radicals. We now report that three Abeta peptides, Abeta-(1-40), Abeta-(25-35), and Abeta-(40-1), do not yield radical adducts with PBN from the Oklahoma Medical Research Foundation (OMRF). In contrast to OMRF PBN, incubation of Sigma PBN in phosphate buffer without Abeta peptides produced a three-line ESR spectrum. It was shown that this nitroxide is di-tert-butylnitroxide and is formed in the Sigma PBN solution as a result of transition metal-catalyzed auto-oxidation of the respective hydroxylamine present as an impurity in the Sigma PBN. Under some conditions, incubation of PBN from Sigma with Abeta-(1-40) or Abeta-(25-35) can stimulate the formation of di-tert-butylnitroxide. It was shown that Abeta peptides enhanced oxidation of cyclic hydroxylamine 1-hydroxy-4-oxo-2,2,6, 6-tetramethylpiperidine (TEMPONE-H), which was strongly inhibited by the treatment of phosphate buffer with Chelex-100. It was shown that ferric and cupric ions are effective oxidants of TEMPONE-H. The data obtained allow us to conclude that under some conditions toxic Abeta peptides Abeta-(1-40) and Abeta-(25-35) enhance metal-catalyzed oxidation of hydroxylamine derivatives, but do not spontaneously form peptide-derived free radicals. PMID:10092619

  2. Effusive molecular beam-sampled Knudsen flow reactor coupled to vacuum ultraviolet single photon ionization mass spectrometry using an external free radical source

    SciTech Connect

    Leplat, N.; Rossi, M. J.

    2013-11-15

    A new apparatus using vacuum ultraviolet single photon ionization mass spectrometry (VUV SPIMS) of an effusive molecular beam emanating from a Knudsen flow reactor is described. It was designed to study free radical-molecule kinetics over a significant temperature range (300–630 K). Its salient features are: (1) external free radical source, (2) counterpropagating molecular beam and diffuse VUV photon beam meeting in a crossed-beam ion source of a quadrupole mass spectrometer with perpendicular ion extraction, (3) analog detection of the photocurrent of the free radical molecular cation, and (4) possibility of detecting both free radicals and closed shell species in the same apparatus and under identical reaction conditions owing to the presence of photoelectrons generated by the photoelectric effect of the used VUV-photons. The measured thermal molecular beam-to-background ratio was 6.35 ± 0.39 for Ar and 10.86 ± 1.59 for i-C{sub 4}H{sub 10} at 300 K, a factor of 2.52 and 1.50 smaller, respectively, than predicted from basic gas-dynamic considerations. Operating parameters as well as the performance of key elements of the instrument are presented and discussed. Coupled to an external free radical source a steady-state specific exit flow of 1.6 × 10{sup 11} and 5.0 × 10{sup 11} molecule s{sup −1} cm{sup −3} of C{sub 2}H{sub 5}{sup •} (ethyl) and t-C{sub 4}H{sub 9}{sup •} (t-butyl) free radicals have been detected using VUV SPIMS at their molecular ion m/z 29 and 57, respectively, at 300 K.

  3. Effusive molecular beam-sampled Knudsen flow reactor coupled to vacuum ultraviolet single photon ionization mass spectrometry using an external free radical source.

    PubMed

    Leplat, N; Rossi, M J

    2013-11-01

    A new apparatus using vacuum ultraviolet single photon ionization mass spectrometry (VUV SPIMS) of an effusive molecular beam emanating from a Knudsen flow reactor is described. It was designed to study free radical-molecule kinetics over a significant temperature range (300-630 K). Its salient features are: (1) external free radical source, (2) counterpropagating molecular beam and diffuse VUV photon beam meeting in a crossed-beam ion source of a quadrupole mass spectrometer with perpendicular ion extraction, (3) analog detection of the photocurrent of the free radical molecular cation, and (4) possibility of detecting both free radicals and closed shell species in the same apparatus and under identical reaction conditions owing to the presence of photoelectrons generated by the photoelectric effect of the used VUV-photons. The measured thermal molecular beam-to-background ratio was 6.35 ± 0.39 for Ar and 10.86 ± 1.59 for i-C4H10 at 300 K, a factor of 2.52 and 1.50 smaller, respectively, than predicted from basic gas-dynamic considerations. Operating parameters as well as the performance of key elements of the instrument are presented and discussed. Coupled to an external free radical source a steady-state specific exit flow of 1.6 × 10(11) and 5.0 × 10(11) molecule s(-1) cm(-3) of C2H5(●) (ethyl) and t-C4H9(●) (t-butyl) free radicals have been detected using VUV SPIMS at their molecular ion m/z 29 and 57, respectively, at 300 K. PMID:24289411

  4. Magnetic Bistability in a Discrete Organic Radical.

    PubMed

    Li, Tao; Tan, Gengwen; Shao, Dong; Li, Jing; Zhang, Zaichao; Song, You; Sui, Yunxia; Chen, Sheng; Fang, Yong; Wang, Xinping

    2016-08-17

    Molecular assembly with magnetic bistability has been of considerable interest for application as electronic devices. In contrast to transition-metal complexes, magnetic bistability so far observed in organic radical crystals is mainly caused by intermolecular electron-exchange interaction. We now report that the magnetic bistability in an organic radical can also be caused by intramolecular electron-exchange interaction. The diradical salt of 1,4-di(bisphenylamino)-2,3,5,6,-tetramethylbenzene undergoes a phase transition with a thermal hysteresis loop over the temperature range from 118 to 131 K. The phases above and below the loop correspond to two different singlet states of the diradical dication. The results provide a novel organic radical material as an unprecedented instance of an intramolecular magnetic bistability revalent to the design of functional materials. PMID:27479783

  5. Radical abdominoplasty, including body shaping: representative cases.

    PubMed

    Mühlbauer, W

    1989-01-01

    Even in the age of liposuction there exist certain situations for which abdominoplasty in its radical form is indicated--for example, redundant skin after radical weight loss, the stigmata of postpregnancy syndrome, and localized accumulation of adipose tissue--the lipodystrophies and resistant generalized obesity. Redundant skin after radical weight loss is resected simultaneously around the abdomen, the lumbar regions, the perineum, and the thighs. The typical stigmata of postpregnancy syndrome may be excised through an extended abdominoplasty combined with simultaneous excision and pexy of the inner aspects of the thighs leaving a "bikini" scar behind. A mastopexy may be added. Genetically predisposed localized lipodystrophies in the abdominal lumbar, and upper thigh region may be resected through a circular abdominoplasty with or without simultaneous resection of the perineum and inner thighs. Abdominal aprons often contain umbilical or ventral hernias that may need to be repaired simultaneously. Representative cases are presented and dangers and complications are discussed. PMID:2741749

  6. Resveratrol products resulting by free radical attack

    NASA Astrophysics Data System (ADS)

    Bader, Yvonne; Quint, R. M.; Getoff, Nikola

    2008-06-01

    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.

  7. Isobaric vapor-liquid equilibria in the system methyl propanoate + n-butyl alcohol

    SciTech Connect

    Susial, P.; Ortega, J. . Lab. de Termodinamica y Fisicoquimica)

    1993-10-01

    Isobaric vapor-liquid equilibria were determined at 74.66, 101.32, and 127.99 kPa for binary mixtures containing methyl propanoate + n-butyl alcohol by using a dynamic still with vapor and liquid circulation. No azeotrope was detected. The data were found to be thermodynamically consistent according to the point to point test. Application of the group-contribution models ASOG, UNIFAC, and modified UNIFAC to the activity coefficients at the three pressures studied gives average errors of less than 10%, 11%, and 3%, respectively.

  8. Chemoselective Nitration of Phenols with tert-Butyl Nitrite in Solution and on Solid Support

    PubMed Central

    Koley, Dipankar; Colón, Olvia C.; Savinov, Sergey N

    2009-01-01

    tert-Butyl nitrite was identified as a safe and chemoselective nitrating agent that provides preferentially mononitro derivatives of phenolic substrates in the presence of potentially competitive functional groups. On the basis of our control experiments, we propose that the reaction proceeds through the formation of O-nitrosyl intermediates prior to C-nitration via homolysis and oxidation. The reported nitration method is compatible with tyrosine-containing peptides on solid support in the synthesis of fluorogenic substrates for characterization of proteases. PMID:19697919

  9. Holmium Nitrate Complexation with Tri-n-butyl Phosphate in Supercritical Carbon Dioxide

    SciTech Connect

    Robert V. Fox; R. Duane Ball; Peter de B. Harrington; Harry W. Rollins; Chien M. Wai

    2005-12-01

    Holmium nitrate pentahydrate was reacted with tri-n-butyl phosphate in supercritical carbon dioxide at 308 K. The products of the complexation reaction were measured under supercritical fluid conditions using UV-vis spectroscopy. The solubility of the metal complexes in the supercritical fluid phase was measured. The mole-ratio titration method was used to determine the stoichiometry of the soluble complexes. Conditional extraction coefficients were calculated from spectral data using least-squares regression and hard-equilibria models. Data indicate that the holmium nitrate-tributyl phosphate system forms 1:2 and 1:4 holmium-tributyl phosphate complexes.

  10. Percutaneous Direct Puncture Embolization with N-butyl-cyanoacrylate for High-flow Priapism.

    PubMed

    Tokue, Hiroyuki; Shibuya, Kei; Ueno, Hiroyuki; Tokue, Azusa; Tsushima, Yoshito

    2016-09-01

    There are many treatment options in high-flow priapism. Those mentioned most often are watchful waiting, Doppler-guided compression, endovascular highly selective embolization, and surgery. We present a case of high-flow priapism in a 57-year-old man treated by percutaneous direct puncture embolization of a post-traumatic left cavernosal arteriovenous fistula using N-butyl-cyanoacrylate. Erectile function was preserved during a 12-month follow-up. No patients with percutaneous direct puncture embolization for high-flow priapism have been reported previously. Percutaneous direct puncture embolization is a potentially useful and safe method for management of high-flow priapism. PMID:27164971

  11. The role of n-butyl-2-cyanoacrylate in the repair of traumatic diaphragmatic injuries

    PubMed Central

    Bas, Gurhan; Ozkan, Orhan Veli; Alimoglu, Orhan; Eryilmaz, Ramazan; Sahin, Mustafa; Okan, Ismail; Cevikbas, Ugur

    2015-01-01

    Diaphragmatic injuries either by blunt or penetrating trauma require prompt surgical intervention and are often exigent to repair. N-butyl-2-cyanoacrylate (n-butyl-2-CA) is a tissue adhesive which has gained wide application in many areas of surgery including emergency. To repair the extensive injuries of the diaphragm it may be necessary the use of synthetic mesh by fixing it with sutures or staples. The use of tissue adhesives may circumvent the potential problems associated with mesh fixation. This study aimed to evaluate the efficacy and safety of tissue adhesives usage for mesh fixation in diaphragmatic injury repair. Twenty-four rats were divided into 3 groups each of them containing 8 rats. A 1- cm diaphragmatic defect was created in all rats. The defect was repaired by polypropylene suture in Group I, by mesh fixed with sutures in group II and by mesh fixed with n-butyl-2-CA in group III. The rats were sacrificed after 1 month. The episode of hernia and the adhesions were assessed by adhesion density score. Also, the abscess and inflammation in the repaired tissue were evaluated microscopically. The Kruskal-Wallis test was performed for the histopathological analysis. No diaphragmatic hernia was detected in any group. While Group III had higher adhesion density scores than group I (P: 0.027), there were no differences between group III and II (P: 0.317) and group II and I (P = 0.095) regarding adhesion density scores. The inflammation grade was higher in group III than group I and II (P < 0.001) and was higher in group II than group I (P < 0.05). There was no differences between each groups, concerning microabcsess formation (P > 0.05). Repair of traumatic diaphragmatic injury in penetrating wound, with polypropylene mesh fixed by n-butyl-2-CA in rats appears to be as efficacious and safe as conventional methods in early period. However, further experimental and clinical study are needed to compare the long-term results of adhesive mesh repair with those of

  12. Postcatheterization Femoral Arteriovenous Fistula: Endovascular Treatment with N-Butyl-Cyanoacrylate Embolization

    SciTech Connect

    Onal, Baran Ilgit, Erhan T.; Akpek, Sergin; Coskun, Bilgen

    2006-04-15

    We report a case of an iatrogenic femoral arteriovenous fistula (AVF) in a 67-year-old man presenting with right femoral bruit on the day after sheath removal for cardiac catheterization. This was successfully treated with embolization using N-butyl-cynoacrylate (NBCA) through a coaxial microcatheter. Transcatheter embolization of iatrogenic femoral AVFs with NBCA in selected cases may be a safe and effective treatment in the presence of long fistula tracts. It is then easy to perform in experienced hands and relatively inexpensive.

  13. Reductive splitting of cellulose in the ionic liquid 1-butyl-3-methylimidazolium chloride.

    PubMed

    Ignatyev, Igor A; Van Doorslaer, Charlie; Mertens, Pascal G N; Binnemans, Koen; De Vos, Dirk E

    2010-01-01

    The depolymerization of cellulose is carried out in the ionic liquid 1-butyl-3-methylimidazolium chloride in the presence of hydrogen gas. First, the ketal 1,1-diethoxycyclohexane and cellobiose were used as model substrates. For the depolymerization of cellulose itself, the combination of a heterogeneous metal catalyst and a homogeneous ruthenium catalyst proved effective. One of the possible roles of the ruthenium compound is to enhance the transfer of hydrogen to the metallic surface. The cellulose is fully converted under relatively mild conditions, with sorbitol as the dominant product in 51-74% yield. PMID:20049766

  14. Butyl­bis­(diphenyl­glyoximato)(pyridine-κN)­cobalt(III)1

    PubMed Central

    Kumar, Sarvendra; Thapa, Suresh

    2012-01-01

    In the title compound, [Co(C4H9)(C14H11N2O2)2(C5H5N)], the CoIII atom is coordinated by a butyl group, a nitro­gen-bonded pyridine and two N,N′-bidentate diphenyl­glyoximate ligands in a distorted octa­hedral geometry. The crystal structure features two short O—H⋯O bridges between the two chelating anions, with O⋯O distances less than 2.5 Å. PMID:22346804

  15. Solid state proton spin relaxation and methyl and t-butyl reorientation

    NASA Astrophysics Data System (ADS)

    Beckmann, Peter A.; Al-Hallaq, Hania A.; Fry, Anne M.; Plofker, Amy L.; Roe, Brian A.; Weiss, Jessica A.

    1994-01-01

    We have measured the temperature T and Larmor frequency ω/2π dependence of the proton spin-lattice relaxation rate R in solid 1-hydroxy-2,4,6-tri-butylbenzene. The data is interpreted in terms of the rotational motion of the t-butyl groups and their constituent methyl groups. Our data is much more extensive than a previous report [J. Yamauchi and C. A. McDowell, J. Chem. Phys. 75, 1051 (1981)] resulting in a revised dynamical model and considerably larger rotational barriers. Interesting thermal history effects are discussed.

  16. Kinetics and mechanisms of cylindrospermopsin destruction by sulfate radical-based advanced oxidation processes.

    PubMed

    He, Xuexiang; de la Cruz, Armah A; O'Shea, Kevin E; Dionysiou, Dionysios D

    2014-10-15

    Cylindrospermopsin (CYN) is a potent cyanobacterial toxin frequently found in water bodies worldwide raising concerns over the safety of drinking and recreational waters. A number of technologies have been investigated to remove and/or degrade cyanotoxins with advanced oxidation processes (AOPs) being among the most promising and effective for water detoxification. In this study, the degradation of CYN by sulfate radical-based UV-254 nm-AOPs was evaluated. The UV/S2O8(2-) (UV/peroxydisulfate) was more efficient than UV/HSO5(-) (UV/peroxysulfate) and UV/H2O2 (UV/hydrogen peroxide) processes when natural water samples were used as reaction matrices. The observed UV fluence based pseudo-first-order rate constants followed the expected order of radical quantum yields. The presence of 200 μM natural organic matter (NOM) as carbon slightly inhibited the destruction of CYN; 1.24 mg L(-1)NO3(-) (nitrate) had no significant influence on the removal efficiency and 50 μg L(-1) Fe(2+) [iron (2+)] or Cu(2+) [copper (2+)] improved the performance of UV/S2O8(2-). The addition of tert-butyl alcohol (t-BuOH; hydroxyl radical scavenger) in the reaction yielded byproducts that indicated specific sites in CYN preferentially attacked by sulfate radicals (SRs). The predominant CYN degradation byproduct was P448 consistent with fragmentation of the C5C6 bond of the uracil ring. The subsequent formation of P420 and P392 through a stepwise loss of carbonyl group(s) further supported the fragmentation pathway at C5C6. The byproduct P432 was identified exclusively as mono-hydroxylation of CYN at tricyclic guanidine ring, whereas P414 was detected as dehydrogenation at the tricyclic ring. The elimination of sulfate group and the opening of tricyclic ring were also observed. The possible degradation pathways of CYN by SR-AOP were presented. PMID:25000199

  17. 5,5'-Di-tert-butyl-2,2'-dihydroxy-3,3'-methylenedibenzaldehyde and 6,6'-di-tert-butyl-8,8'-methylenebis(spiro[4H-1,3-benzodioxin-2,1'-cyclohexane]).

    PubMed

    Masci, Bernardo; Mortera, Stefano Levi; Seralessandri, Luca; Thuéry, Pierre

    2004-02-01

    Two related compounds containing p-tert-butyl-o-methylene-linked phenol or phenol-derived subunits are described, namely 5,5'-di-tert-butyl-2,2'-dihydroxy-3,3'-methylenedibenzaldehyde, C(23)H(28)O(4), (I), and 6,6'-di-tert-butyl-8,8'-methylenebis(spiro[4H-1,3-benzodioxin-2,1'-cyclohexane]), C(35)H(48)O(4), (II). Both compounds adopt a 'butterfly' shape, with the two phenol or phenol-derived O atoms in distal positions. Phenol and aldehyde groups in (I) are involved in intramolecular hydrogen bonds and the two dioxin rings in (II) are in distorted half-chair conformations. PMID:14767128

  18. Total radical yields from tropospheric ethene ozonolysis.

    PubMed

    Alam, Mohammed S; Camredon, Marie; Rickard, Andrew R; Carr, Timo; Wyche, Kevin P; Hornsby, Karen E; Monks, Paul S; Bloss, William J

    2011-06-21

    The gas-phase reactions of ozone with alkenes can be significant sources of free radicals (OH, HO(2) and RO(2)) in the Earth's atmosphere. In this study the total radical production and degradation products from ethene ozonolysis have been measured, under conditions relevant to the troposphere, during a series of detailed simulation chamber experiments. Experiments were carried out in the European photoreactor EUPHORE (Valencia, Spain), utilising various instrumentation including a chemical-ionisation-reaction time-of-flight mass-spectrometer (CIR-TOF-MS) measuring volatile organic compounds/oxygenated volatile organic compounds (VOCs/OVOCs), a laser induced fluorescence (LIF) system for measuring HO(2) radical products and a peroxy radical chemical amplification (PERCA) instrument measuring HO(2) + ΣRO(2). The ethene + ozone reaction system was investigated with and without an OH radical scavenger, in order to suppress side reactions. Radical concentrations were measured under dry and humid conditions and interpreted through detailed chemical chamber box modelling, incorporating the Master Chemical Mechanism (MCMv3.1) degradation scheme for ethene, which was updated to include a more explicit representation of the ethene-ozone reaction mechanism.The rate coefficient for the ethene + ozone reaction was measured to be (1.45 ± 0.25) × 10(-18) cm(3) molecules(-1) s(-1) at 298 K, and a stabilised Criegee intermediate yield of 0.54 ± 0.12 was determined from excess CO scavenger experiments. An OH radical yield of 0.17 ± 0.09 was determined using a cyclohexane scavenger approach, by monitoring the formation of the OH-initiated cyclohexane oxidation products and HO(2). The results highlight the importance of knowing the [HO(2)] (particularly under alkene limited conditions and high [O(3)]) and scavenger chemistry when deriving radical yields. An averaged HO(2) yield of 0.27 ± 0.07 was determined by LIF/model fitting. The observed yields are interpreted in terms of

  19. Resonance ionization detection of combustion radicals

    SciTech Connect

    Cool, T.A.

    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.

  20. Evolution of radical mastectomy for breast cancer

    PubMed Central

    Plesca, M; Bordea, C; El Houcheimi, B; Ichim, E; Blidaru, A

    2016-01-01

    Surgical treatment of breast cancer has been marked by a constant evolution since the Halsted radical mastectomy described in the late 19th century has become the current standard Madden radical mastectomy, a breast surgery that involves the ablation of tissue with the axillary lymphatic preserving both pectoral muscles. The purpose of this paper was to present the stages that have marked the evolution of this intervention and to provide an overview of the way breast cancer has been understood and treated in the last century. PMID:27453752

  1. Cell damage by oxygen free radicals.

    PubMed

    Bellomo, G

    1991-02-01

    The exposure of isolated and cultured cells to oxygen free radicals generated extracellularly or intracellularly during the metabolism of foreing compounds results in the development of damage that eventually lead to cell death. Multiple mechanisms are involved in these cytopathological processes, including direct attack of free radicals to macromolecules essential for cell life, as well as indirect activation of catabolic processes such as proteases, endonucleases and phospholipases. A key role in triggering these indirect events is played by Ca(2+) whose cytosolic concentration during oxidative stress raises well above the physiological limits. PMID:22358959

  2. [Robot-assisted radical prostatectomy: surgical techniques].

    PubMed

    Kojima, Yoshiyuki; Sato, Yuichi; Ogawa, Soichiro; Haga, Nobuhiro; Yanagida, Tomohiko

    2016-01-01

    Robot-assisted radical prostatectomy (RARP) for the patients with localized prostate cancer is increasingly being adopted around the world. The da Vinci surgical system (Intuitive Surgical, Sunnyvale, CA, USA) provides the advantages of simplification and precision of exposure and suturing because of allowing movements of the robotic arm in real time with increased degree of freedom and magnified 3-dimensional view. Therefore, RARP has been expected to provide superior therapeutic benefit to patients in terms of surgical outcome to open or laparoscopic radical prostatectomy. In this review, we provide our technical aspects and tips and tricks of RARP to improve surgical outcome and postoperative quality of life. PMID:26793888

  3. Radical Behaviorism and Buddhism: Complementarities and Conflicts

    PubMed Central

    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 respective goals, conceptualization of human beings, and the outcomes of following either philosophy. From these comparisons it is concluded that the commonalities discerned between these two philosophies may enhance both philosophical systems. PMID:22478509

  4. Free-radical kinetics of coal liquefaction

    SciTech Connect

    Wang, M.; Smith, J.M.; McCoy, B.J.

    1994-07-16

    A rate expression with first- and second-order terms in the concentration of extractable compounds in solid coal particles is derived from a fundamental free-radical mechanism. The expression was suggested empirically by prior experiments for coal liquefaction in the presence of a hydrogen-donor solvent. Radical reactions are considered to occur in both coal and in solvent. The long-chain approximation justifies the neglect of initiation, hydrogen abstraction, and termination rates as quantitatively insignificant relative to propagation reaction rates.

  5. Resonant cavity spectroscopy of radical species

    NASA Astrophysics Data System (ADS)

    Ritchie, Grant

    2015-04-01

    Photo-oxidation in the troposphere is highly complex, being initiated by short lived radical species, in the daytime dominated by the hydroxyl radical, OH, with contributions from Cl atoms, and at night by either NO3 radicals or ozone. Chemical oxidation cycles, which couple OH, HO2 and peroxy (RO2) radical species, remove primary emitted trace species which are harmful to humans or to the wider environment. However, many of the secondary products produced by atmospheric photo-oxidation are also directly harmful, for example O3, NO2, acidic and multifunctional species, many of which are of low volatility and are able to partition effectively to the condensed phase, creating secondary organic aerosol (SOA), which contributes a significant fraction of tropospheric aerosol, with associated impacts on climate and human health. The accuracy of atmospheric models to predict these impacts necessarily requires accurate knowledge of the chemical oxidative cycling. Two of the simplest intermediates are the hydroperoxy radical, HO2, and the smallest and dominant organic peroxy radical, CH3O2, formed directly by the reactions of OH with CO/O2 and CH4/O2, respectively, and indirectly following the oxidation of larger VOCs. OH, HO2 and RO2 (collectively known as ROx) are rapidly cycled, being at the centre of tropospheric oxidation, and hence are some of the best targets for models to compare with field data. The reaction of HO2 and RO2 with NO constitutes the only tropospheric in-situ source of O3. Despite their importance, neither HO2 nor CH3O2 is measured directly in the atmosphere. HO2 is only measured indirectly following its conversion to OH and CH3O2 is not measured at all. Typically only the sum of RO2 radicals is measured, making no distinction between different organic peroxy radicals. This contribution will detail recent studies using (i) optical feedback cavity enhanced absorption spectroscopy with both quantum and inter-band cascade lasers in the mid-IR, and (ii

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

    PubMed

    Fiser, Béla; Jójárt, Balázs; Csizmadia, Imre G; Viskolcz, Béla

    2013-01-01

    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. PMID:24040010

  7. Radical scavenging ability of some compounds isolated from Piper cubeba towards free radicals.

    PubMed

    Aboul-Enein, Hassan Y; Kładna, Aleksandra; Kruk, Irena

    2011-01-01

    The purpose of this study was to identify the antioxidant activity of 16 compounds isolated from Piper cubeba (CNCs) through the extent of their capacities to scavenge free radicals, hydroxyl radical (HO(•)), superoxide anion radical O•(2)(-) and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH(•)), in different systems. Electron paramagnetic resonance (EPR) and 5,5-dimethyl-1-pyrroline-N-oxide, DMPO, as the spin trap, and chemiluminescence techniques were applied. Using the Fenton-like reaction [Fe(II) + H(2)O(2)], CNCs were found to inhibit DMPO-OH radical formation ranging from 5 to 57% at 1.25 mmol L(-1) concentration. The examined CNCs also showed a high DPPH antiradical activity (ranging from 15 to 99% at 5 mmol L(-1) concentration). Furthermore, the results indicated that seven of the 16 tested compounds may catalyse the conversion of superoxide radicals generated in the potassium superoxide/18-crown-6 ether system, thus showing superoxide dismutase-like activity. The data obtained suggest that radical scavenging properties of CNCs might have potential application in many plant medicines. PMID:21681910

  8. Acid-Assisted Ball Milling of Cellulose as an Efficient Pretreatment Process for the Production of Butyl Glycosides.

    PubMed

    Boissou, Florent; Sayoud, Nassim; De Oliveira Vigier, Karine; Barakat, Abdellatif; Marinkovic, Sinisa; Estrine, Boris; Jérôme, François

    2015-10-12

    Ball milling of cellulose in the presence of a catalytic amount of H2SO4 was found to be a promising pre-treatment process to produce butyl glycosides in high yields. Conversely to the case of water, n-butanol has only a slight effect on the recrystallization of ball-milled cellulose. As a result, thorough depolymerization of cellulose prior the glycosylation step is no longer required, which is a pivotal aspect with respect to energy consumption. This process was successfully transposed to wheat straw from which butyl glycosides and xylosides were produced in good yields. Butyl glycosides and xylosides are important chemicals as they can be used as hydrotropes but also as intermediates in the production of valuable amphiphilic alkyl glycosides. PMID:26346950

  9. Oxidation of 2,6-di-tert-butyl-4-methylphenol. The structure of C14H22O3

    USGS Publications Warehouse

    Yohe, G.R.; Dunbar, J.E.; Lansford, M.W.; Pedrotti, R.L.; Scheidt, F.M.; Lee, F.G.H.; Smith, E.C.

    1959-01-01

    The acidic compound C14H22O3, previously reported without assignment of structure as an oxidation product of 2,6-di-tert-butyl-4-methylphenol, is now believed to be DL-trans-5,6-di-tert-butyl-2-hydroxy-1,4-diketo-2-cyclohexene (I). Chemical properties are described and infrared spectra are presented in support of this structure. This structure is of interest in relation to the problem of the existence of o-di-tert-alkylbenzene derivatives. The relatively easy racemization of optically active I suggests that its completely enolized form, 5,6-di-tert-butyl-1,2,4-trihydroxybenzene, is capable of transitory existence.

  10. Molecular recognition of curcumin (Indian Ayurvedic medicine) by the supramolecular probe, p-t-butyl calix(8)arene

    NASA Astrophysics Data System (ADS)

    Meenakshi, C.; Jayabal, P.; Ramakrishnan, V.

    2014-06-01

    The thermodynamic property of the host-guest complexes formed between the curcumin, component of Indian Ayurvedic medicine turmeric, a drug molecule, with the supra molecule, p-t-butyl calix(8)arene was studied. p-t-Butyl calix(8)arene has been used as a host molecule and curcumin as a guest molecule. Optical absorption spectral studies were carried out to investigate the molecular recognition properties of p-t-butyl calix(8)arene with curcumin. The stochiometry of the host-guest complexes formed and the binding constant were determined. An interesting 1:1 and 4:1 stochiometric host-guest complexes were formed. Job's continuous method of variation and Benesi-Hildebrand expression were used for the determination of binding constant and the stochiometry of the host-guest complex formed.

  11. Room-Temperature Electron Spin Relaxation of Triarylmethyl Radicals at the X- and Q-Bands.

    PubMed

    Kuzhelev, Andrey A; Trukhin, Dmitry V; Krumkacheva, Olesya A; Strizhakov, Rodion K; Rogozhnikova, Olga Yu; Troitskaya, Tatiana I; Fedin, Matvey V; Tormyshev, Victor M; Bagryanskaya, Elena G

    2015-10-29

    Triarylmethyl radicals (trityls, TAMs) represent a relatively new class of spin labels. The long relaxation of trityls at room temperature in liquid solutions makes them a promising alternative for traditional nitroxides. In this work we have synthesized a series of TAMs including perdeuterated Finland trityl (D36 form), mono-, di-, and triester derivatives of Finland-D36 trityl, the deuterated form of OX63, the dodeca-n-butyl homologue of Finland trityl, and triamide derivatives of Finland trityl with primary and secondary amines attached. We have studied room-temperature relaxation properties of these TAMs in liquids using pulsed electron paramagnetic resonance (EPR) at two microwave frequency bands. We have found the clear dependence of phase memory time (Tm ∼ T2) on the magnetic field: room-temperature Tm values are ∼1.5-2.5 times smaller at the Q-band (34 GHz, 1.2 T) than at the X-band (9 GHz, 0.3 T). This trend is ascribed to the contribution from g-anisotropy that is negligible at lower magnetic fields but comes into play at the Q-band. In agreement with this, the difference between T1 and Tm becomes more pronounced at the Q-band than at the X-band due to increased contributions from incomplete motional averaging of g-anisotropy. Linear dependence of (1/Tm - 1/T1) on viscosity implies that g-anisotropy is modulated by rotational motion of the trityl radical. On the basis of the analysis of previous data and results of the present work, we conclude that, in the general situation where the spin label is at least partly mobile, the X-band is most suitable for application of trityls for room-temperature pulsed EPR distance measurements. PMID:26001103

  12. Application of UV-Vis spectrophotometric process for the assessment of indoloacridines as free radical scavenger.

    PubMed

    Sridharan, Makuteswaran; Prasad, K J Rajendra; Madhumitha, G; Al-Dhabi, Naif Abdullah; Arasu, Mariadhas Valan

    2016-09-01

    A conventional approach has been used to synthesis Indole fused acridine, 4a-e. In this paper to achieve the target molecule, 4 the reaction was performed via two steps. In step 1, there was a reaction between Carbazolone, 1 and benzophenone, 2 to get dihydroindoloacridine, 3. In step 2, compound, 3 was treated with 5% Palladium/Carbon in the presence of diphenyl ether for 5h to give a dark brown product, 4. The column chromatography was used to purify final product, 4. All the synthesized compounds such as 3 and 4 were characterized by melting point, FTIR, (1)H NMR, and Mass spectra. Further to check the purity of the compounds it was subjected to CHN analyzer. The target molecules such as 3 and 4 were screened for antimicrobial studies against bacteria such as Bacillus subtilis (B. subtilis), Staphylococcus aureus (S. aureus), Klebsiella pneumonia (K. pneumonia), Salmonella typhi (S. typhi); and fungi like Aspergillus niger (A. niger), Aspergillus fumigatus (A. fumigatus). The obtained results clearly proves that the target molecules shown reasonable activity against K. pneumonia and A. niger. Further the compounds were screened for free radical scavenging activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH). The free radical scavenging property was performed using UV-Visible spectroscopy. The results were compared with the standard BHT (Butylated Hydroxy Toluene). Compounds, 4a and 4e were shown higher percentage of inhibition when compare to the standard. The result confirms that further research on indoloacridine will leads effective drug to the market. PMID:27491030

  13. Formation of hydroxyl radicals from photolysis of secondary organic aerosol material

    NASA Astrophysics Data System (ADS)

    Badali, K. M.; Zhou, S.; Aljawhary, D.; Antiñolo, M.; Chen, W. J.; Lok, A.; Mungall, E.; Wong, J. P. S.; Zhao, R.; Abbatt, J. P. D.

    2015-02-01

    This paper demonstrates that OH radicals are formed by photolysis of secondary organic aerosol (SOA) material formed by terpene ozonolysis. The SOA aerosol is collected on filters, dissolved in water containing a radical trap (benzoic acid), and then exposed to ultraviolet light in a photochemical reactor. The OH formation rates, which are similar for both α-pinene and limonene SOA, are measured from the formation rate of p-hydroxybenzoic acid as measured using offline HPLC analysis. To evaluate whether the OH is formed by photolysis of H2O2 or organic hydroperoxides (ROOH), the peroxide content of the SOA was measured using the horseradish peroxidase-dichlorofluorescein (HRP-DCF) assay, which was calibrated using H2O2. The OH formation rates from SOA are five times faster than from the photolysis of H2O2 solutions whose concentrations correspond to the peroxide content of the SOA solutions assuming that the HRP-DCF signal arises from H2O2 alone. The higher rates of OH formation from SOA are likely due to ROOH photolysis. This result is substantiated by photolysis experiments conducted with t-butyl hydroperoxide and cumene hydroperoxide which produce over three times more OH than photolysis of equivalent concentrations of H2O2. Relative to the peroxide level in the SOA, the quantum yield for OH generation from α-pinene SOA is 0.8 ± 0.4. This is the first demonstration of an efficient photolytic source of OH in SOA, one that may affect both cloudwater and aerosol chemistry.

  14. Formation of hydroxyl radicals from photolysis of secondary organic aerosol material

    NASA Astrophysics Data System (ADS)

    Badali, K. M.; Zhou, S.; Aljawhary, D.; Antiñolo, M.; Chen, W. J.; Lok, A.; Mungall, E.; Wong, J. P. S.; Zhao, R.; Abbatt, J. P. D.

    2015-07-01

    This paper demonstrates that OH radicals are formed by photolysis of secondary organic aerosol (SOA) material formed by terpene ozonolysis. The SOA is collected on filters, dissolved in water containing a radical trap (benzoic acid), and then exposed to ultraviolet light in a photochemical reactor. The OH formation rates, which are similar for both α-pinene and limonene SOA, are measured from the formation rate of p-hydroxybenzoic acid as measured using offline HPLC analysis. To evaluate whether the OH is formed by photolysis of H2O2 or organic hydroperoxides (ROOH), the peroxide content of the SOA was measured using the horseradish peroxidase-dichlorofluorescein (HRP-DCF) assay, which was calibrated using H2O2. The OH formation rates from SOA are 5 times faster than from the photolysis of H2O2 solutions whose concentrations correspond to the peroxide content of the SOA solutions, assuming that the HRP-DCF signal arises from H2O2 alone. The higher rates of OH formation from SOA are likely due to ROOH photolysis, but we cannot rule out a contribution from secondary processes as well. This result is substantiated by photolysis experiments conducted with t-butyl hydroperoxide and cumene hydroperoxide which produce over 3 times more OH than photolysis of equivalent concentrations of H2O2. Relative to the peroxide level in the SOA and assuming that the peroxides drive most of the ultraviolet absorption, the quantum yield for OH generation from α-pinene SOA is 0.8 ± 0.4. This is the first demonstration of an efficient photolytic source of OH in SOA, one that may affect both cloud water and aerosol chemistry.

  15. The interaction of 1-butyl iodide with the Mo 2C/Mo( 1 0 0 ) surface

    NASA Astrophysics Data System (ADS)

    Bugyi, L.; Oszkó, A.; Solymosi, F.

    2004-07-01

    The adsorption and dissociation of 1-butyl iodide and the reactions of butyl species have been investigated on the Mo 2C/Mo(1 0 0) surface by thermal desorption spectroscopy (TDS), X-ray photoelectron spectroscopy (XPS) and high resolution electron energy loss spectroscopy (HREELS) in the temperature-range of 100-1200 K. 1-Butyl iodide adsorbed molecularly on the clean Mo 2C/Mo(1 0 0) surface at 100 K. A fraction of the C 4H 9I (a) desorbed in two peaks at 166 and 280 K, characteristic of condensed and weakly adsorbed layers, respectively. XPS data indicated that the scission of the C-I bond in C 4H 9I (a) started at as low temperature as 140 K and was completed at 280-300 K. The promotion of rupture of the C-I bond in the adsorbed 1-butyl iodide was achieved by UV irradiation even at 100 K. The dissociation process was not accompanied by any significant changes in the HREEL spectra. Among the reaction products, the thermal desorption of butane was characterized by Tp=246-290 K and that of butene by Tp=246 and 322 K, suggesting the disproportionation reaction of butyl groups. The release of both compounds was a reaction-rate limited process, as confirmed by the separate determination of their bonding to the Mo 2C/Mo(1 0 0) surface. A very limited coupling of butyl species was indicated by the desorption of octane with Tp˜415 K. Heating the adsorbed layer to 470 K the formation of adsorbed butylidyne group was detected, which decomposed to carbon and hydrogen above 600 K.

  16. RadicalLocator: A software tool for identifying the radicals in Chinese characters.

    PubMed

    Yu, Lili; Reichle, Erik D; Jones, Mathew; Liversedge, Simon P

    2015-09-01

    This article describes a new software tool called RadicalLocator that can be used to automatically identify (e.g., for visual inspection) individual target radicals (i.e., groups of strokes) in written Chinese characters. We first briefly clarify why this software is useful for research purposes and discuss the factors that make this pattern recognition task so difficult. We then describe how the software can be downloaded and installed, and used to identify the radicals in characters for the purposes of, for example, selecting materials for psycholinguistic experiments. Finally, we discuss several known limitations of the software and heuristics for addressing them. PMID:25169830

  17. Determination of methacrylic acid in food simulants by pyrolytic butylation-gas chromatography.

    PubMed

    Huang, Zhongping; Qiu, Ruofeng; Liu, Tingfei; Huang, Yilei; Zhu, Zuoyi; Wang, Lili

    2016-07-01

    An on-line pyrolytic butylation approach was proposed to determine methacrylic acid (MA) in food simulants by gas chromatography (GC) without an expensive pyrolyzer. MA in food simulants was converted into butyl methacrylate in the presence of tetrabutylammonium hydroxide (TBAH) without any pretreatment at 330°C in the injection-port, contributing to high GC signal response. The derivatizing conditions for the proposed method were optimized, namely the injection-port temperature, type and amount of the organic alkaline used for derivatization. A series of standard solutions of MA in the range of 1.0-50mg/kg were analyzed with correlation coefficient r≥0.9975. The limits of detection (LODs) were less than 0.15mg/kg for MA in four matrix simulants (distilled water, 3%w/v acetic acid, 10%v/v ethanol, and isooctane). Relative standard deviations (RSDs) for retention time, peak height and peak area were all less than 3.88%. The technique was successfully applied to the analysis of MA migrating from plastic cup samples, with recoveries of added MA in the range of 96.5-123.0%. Direct injection of the simulants into the GC system after migration tests, without any pretreatment step, makes the developed method of great value for rapid screening analysis of samples in bulks. PMID:27262371

  18. Ultrasound Treatment of Butyl Gum and Rubber, Studied by NMR Relaxation

    NASA Astrophysics Data System (ADS)

    von Meerwall, E. D.; Feng, Wenlai; Isayev, A. I.

    2004-10-01

    We have examined the effects of intense ultrasound on butyl gum and unfilled vulcanizates using proton transverse NMR relaxation, sol extraction, GPC analysis, and glass transition measurements. At 100 deg.C the spin echo decays exhibit three components, due to entangled molecules and network, unentangled sol plus dangling chain ends, and oligomer remnants; two components suffice to describe most vulcanizates. Compared to other rubbers we have studied, all component spin relaxation times are shorter and less sensitive to ultrasound, and the fraction of the short-T2 component is significantly higher. In the gums sonication produces chain scission but no significant crosslinking. In sol extracted from sonicated rubber, the T2 component amplitudes correlate well with the trimodal molecular-weight distribution. In spite of the low glass transition temperatures (near -60 deg.C) even the longest T2 up to 120 deg.C was too short to permit pulsed-gradient diffusion measurements. The low extractable sol fraction at standard ultrasound settings confirms the conclusion that in butyl rubber sonication is less effective for network destruction than in other rubbers.

  19. Singlet exciton fission in thin films of tert-butyl-substituted terrylenes.

    PubMed

    Eaton, Samuel W; Miller, Stephen A; Margulies, Eric A; Shoer, Leah E; Schaller, Richard D; Wasielewski, Michael R

    2015-05-01

    Two terrylene chromophores, 2,5,10,13-tetra(tert-butyl)terrylene (1) and 2,5-di(tert-butyl)terrylene (2), were synthesized and studied to determine their singlet exciton fission (SF) efficiencies. Compound 1 crystallizes in one-dimensional stacks, whereas 2 packs in a slip-stacked, herringbone pattern of dimers motif. Strongly quenched fluorescence and rapid singlet exciton decay dynamics are observed in vapor-deposited thin films of 1 and 2. Phosphorescence measurements on thin films of 1 and 2 show that SF is only 70 meV endoergic for these chromophores. Femtosecond transient absorption experiments using low laser fluences on these films reveal rapid triplet exciton formation for both 1 (τ = 120 ± 10 ps) and 2 (τ = 320 ± 20 ps) that depends strongly on film crystallinity. The transient absorption data are consistent with formation of an excimer state prior to SF. Triplet exciton yield measurements indicate nearly quantitative SF in thin films of both chromophores in highly crystalline solvent-vapor-annealed films: 170 ± 20% for 1 and 200 ± 30% for 2. These results show that significantly different crystal morphologies of the same chromophore can both result in high-efficiency SF provided that the energetics are favorable. PMID:25856414

  20. Effect of butyl paraben on the development and microbial composition of periphyton.

    PubMed

    Song, Chaofeng; Lin, Juan; Huang, Xiaolong; Wu, Yonghong; Liu, Jiantong; Wu, Chenxi

    2016-03-01

    Parabens are extensively used as preservatives and bactericides in personal care and other consumer products, and are commonly found in wastewater and surface water as contaminants. However, few data are currently available on the ecotoxicity of parabens. Periphyton biofilm, a widely distributed microbial aggregate of ecological importance in aquatic environment, is frequently used for water quality monitoring, ecological restoration, and toxicity assessment. In this work, the effects of butyl paraben on the development and microbial composition of periphyton biofilm was studied in a laboratory experiment for 32 days using flow through channels. No effect was observed at the environmental relevant concentration level (0.5 μg L(-1)) during the experiment. At the highest tested concentration level (5000 μg L(-1)), following effects were noted: (1) inhibition on algae growth at the end of the experiment as indicated by the chlorophyll a and total biovolume; (2) inhibition of photosynthetic efficiency on day 24 as suggested by the maximal Photosystem II quantum yield (Fv/Fm); (3) decrease of the algal diversity on day 24 and 32 as reflected by the Pielou and Shannon-Weiner indices. Bacteria were less sensitive than algae in the periphyton biofilm, which showed no difference at all tested concentration levels as illustrated by the Biolog EcoPlates™ analysis. Therefore, we conclude that environmental residues of butyl paraben have a very low risk to periphyton in aquatic ecosystems. PMID:26590928

  1. Isolation of a Bacterial Culture That Degrades Methyl t-Butyl Ether

    PubMed Central

    Salanitro, J. P.; Diaz, L. A.; Williams, M. P.; Wisniewski, H. L.

    1994-01-01

    We have isolated a mixed bacterial culture (BC-1) which is capable of degrading the gasoline oxygenate methyl t-butyl ether (MTBE). BC-1 was developed from seed microorganisms present in a chemical plant biotreater sludge. This enrichment culture has been maintained in continuous culture treating high concentrations of MTBE (120 to 200 mg/liter) as the sole carbon source in a simple feed containing NH4+, PO43-, Mg2+, and Ca2+ nutrients. The unit had a stable MTBE removal rate when maintained with a long cell retention time (ca. 80 to 90 days); however, when operated at a ≤50-day cell waste rate, loss of MTBE-degrading activity was observed. The following three noteworthy experimental data show that MTBE is biodegraded extensively by BC-1: (i) the continuous (oxygen-sparged) culture was able to sustain a population of autotrophic ammonia-oxidizing bacteria which could nitrify influent NH4+ concentrations at high rates and obtain CO2 (sole carbon source for growth) from the metabolism of the alkyl ether, (ii) BC-1 metabolized radiolabeled either (14CH3O-MTBE) to 14CO2 (40%) and 14C-labeled cells (40%), and (iii) cell suspensions of the culture were capable of degrading (substrate depletion experiments) MTBE to t-butyl alcohol, a primary metabolite of MTBE. BC-1 is a mixed culture containing several bacterial species and is the first culture of its kind which can completely degrade an alkyl ether. PMID:16349335

  2. Conformations of unsymmetrical N- t-butyl- N-substituted 2-phenylacetamides

    NASA Astrophysics Data System (ADS)

    Petrović, S. D.; Stojanović, N. D.; Antonović, D. G.; Mijin, D. Ž.; Nikolić, A. D.

    1997-06-01

    Various N- t-butyl- N-substituted 2-phenylacetamides, PhCH 2CON( t-Bu)R, wherein R is methyl, ethyl, n-propyl, n-butyl, i-propyl, phenyl and cyclohexyl, were synthesized. Depending on the kind of substituent on the nitrogen atom, some of the examined amides exist in different conformational forms. 1H NMR and 13C NMR spectra of these unsymmetrically N, N-disubstituted amides have been studied and peaks have been assigned in each case to the two possible conformational isomers, arising from the lack of free rotation about the C(O)N bond. The relative distribution of cis and trans isomers has been established by means of different coupling constants and the NOE difference technique. Information about fragmentation routes, and the effect of overall and partial structures were obtained by the study of the metastable ions. The results are in accordance with our previous investigations of the structures of N, N-disubstituted 2-phenylacetamides.

  3. Phases and phase changes in clusters of tert-butyl thiol

    NASA Astrophysics Data System (ADS)

    Hovick, James W.; Bartell, Lawrence S.

    1997-09-01

    Clusters of tert-butyl thiol (TBT) were generated by condensation of vapor in supersonic flow under various expansion conditions, and their structures were examined during their free flight by electron diffraction. The system had been selected because of its similarity to tert-butyl chloride (TBC), a much more thoroughly studied material with an interesting solid-state chemistry. The warmest crystalline phase of TBT observed for the clusters (diameter, ≈ 130 Å) was the known high-temperature cubic phase I with a lattice constant of 8.609(5) Å at ≈ 160 K. A second phase into which phase I nucleated at a rate of ≈ 10 28 m -3 s -1 at about 157 K was also observed, as well as a third phase generated under conditions of very cold flow. All of the phases gave the rapidly damped, diffuse diffraction patterns characteristic of submicroscopic, poorly ordered, plastically crystalline materials. Patterns were far less distinct than those of TBC, and the structures of the colder two phases could not be determined. From the rapid nucleation rate of phase I into the second phase, it could be inferred that a major translational rearrangement of the molecules could not have been involved.

  4. Hydrolysis of the quinone methide of butylated hydroxytoluene in aqueous solutions.

    PubMed

    Willcockson, Maren Gulsrud; Toteva, Maria M; Stella, Valentino J

    2013-10-01

    Butylated hydroxytoluene or BHT is an antioxidant commonly used in pharmaceutical formulations. BHT upon oxidation forms a quinone methide (QM). QM is a highly reactive electrophilic species that can undergo nucleophilic addition. Here, the kinetic reactivity of QM with water at various apparent pH values in a 50% (v/v) water-acetonitrile solution at constant ionic strength of I = 0.5 (NaCl)4 , was studied. The hydrolysis of QM in the presence of added acid, base, sodium chloride, and phosphate buffer resulted in the formation of only one product--the corresponding 3,5-di-tert-butyl-4-hydroxybenzyl alcohol (BA). The rate of BA formation was catalyzed by the addition of acid and base, but not chloride and phosphate species. Nucleophilic excipients, used in the pharmaceutical formulation, or nucleophilic groups on active pharmaceutical ingredient molecule may form adducts with QM, the immediate oxidative product of BHT degradation, thus having implications for drug product impurity profiles. Because of these considerations, BHT should be used with caution in formulations containing drugs or excipients capable of acting as nucleophiles. PMID:23873381

  5. Biodegradation of Methyl tert-Butyl Ether by Co-Metabolism with a Pseudomonas sp. Strain.

    PubMed

    Li, Shanshan; Wang, Shan; Yan, Wei

    2016-01-01

    Co-metabolic bioremediation is supposed to be an impressive and promising approach in the elimination technology of methyl tert-butyl ether (MTBE), which was found to be a common pollutant worldwide in the ground or underground water in recent years. In this paper, bacterial strain DZ13 (which can co-metabolically degrade MTBE) was isolated and named as Pseudomonas sp. DZ13 based on the result of 16S rRNA gene sequencing analysis. Strain DZ13 could grow on n-alkanes (C₅-C₈), accompanied with the co-metabolic degradation of MTBE. Diverse n-alkanes with different carbon number showed a significant influence on the degradation rate of MTBE and accumulation of tert-butyl alcohol (TBA). When Pseudomonas sp. DZ13 co-metabolically degraded MTBE with n-pentane as the growth substrate, a higher MTBE-degrading rate (Vmax = 38.1 nmol/min/mgprotein, Ks = 6.8 mmol/L) and lower TBA-accumulation was observed. In the continuous degradation experiment, the removal efficiency of MTBE by Pseudomonas sp. Strain DZ13 did not show an obvious decrease after five times of continuous addition. PMID:27608032

  6. Designed metalloprotein stabilizes a semiquinone radical

    NASA Astrophysics Data System (ADS)

    Ulas, Gözde; Lemmin, Thomas; Wu, Yibing; Gassner, George T.; Degrado, William F.

    2016-04-01

    Enzymes use binding energy to stabilize their substrates in high-energy states that are otherwise inaccessible at ambient temperature. Here we show that a de novo designed Zn(II) metalloprotein stabilizes a chemically reactive organic radical that is otherwise unstable in aqueous media. The protein binds tightly to and stabilizes the radical semiquinone form of 3,5-di-tert-butylcatechol. Solution NMR spectroscopy in conjunction with molecular dynamics simulations show that the substrate binds in the active site pocket where it is stabilized by metal-ligand interactions as well as by burial of its hydrophobic groups. Spectrochemical redox titrations show that the protein stabilized the semiquinone by reducing the electrochemical midpoint potential for its formation via the one-electron oxidation of the catechol by approximately 400 mV (9 kcal mol-1). Therefore, the inherent chemical properties of the radical were changed drastically by harnessing its binding energy to the metalloprotein. This model sets the basis for designed enzymes with radical cofactors to tackle challenging chemistry.

  7. Radical Negativity: Music Education for Social Justice

    ERIC Educational Resources Information Center

    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…

  8. Designed metalloprotein stabilizes a semiquinone radical

    PubMed Central

    Ulas, Gözde; Lemmin, Thomas; Wu, Yibing; Gassner, George T.; DeGrado, William F.

    2016-01-01

    Enzymes use binding energy to stabilize their substrates in high-energy states that are otherwise inaccessible at ambient temperature. Here we show that a de novo designed Zn(ii) metalloprotein stabilizes a chemically reactive organic radical that is otherwise unstable in aqueous media. The protein binds tightly to and stabilizes the radical semiquinone form of 3,5-di-tert-butylcatechol. Solution NMR spectroscopy in conjunction with molecular dynamics simulations show that the substrate binds in the active site pocket where it is stabilized by metal–ligand interactions as well as by burial of its hydrophobic groups. Spectrochemical redox titrations show that the protein stabilized the semiquinone by reducing the electrochemical midpoint potential for its formation via the one-electron oxidation of the catechol by approximately 400 mV (9 kcal mol−1). Therefore, the inherent chemical properties of the radical were changed drastically by harnessing its binding energy to the metalloprotein. This model sets the basis for designed enzymes with radical cofactors to tackle challenging chemistry. PMID:27001731

  9. Radical Agendas? The Politics of Adult Education.

    ERIC Educational Resources Information Center

    Westwood, Sallie, Ed.; Thomas, J. E., Ed.

    This book brings together eight of the most significant papers published in the journal "Studies in the Education of Adults" from the 1970s and 1980s, together with three new essays that place the earlier material in context. It examines the changes in British adult education between 1970 and 1990 and is concerned with the place of radicalism in…

  10. Serendipitous findings while researching oxygen free radicals.

    PubMed

    Floyd, Robert A

    2009-04-15

    This review is based on the honor of receiving the Discovery Award from the Society of Free Radical Biology and Medicine. The review is reflective and presents our thinking that led to experiments that yielded novel observations. Critical questioning of our understanding of oxygen free radicals in biomedical problems led us to use and develop more direct and extremely sensitive methods. This included nitrone free radical spin trapping and HPLC-electrochemical detection. This technology led to the pioneering use of salicylate to trap hydroxyl free radicals and show increased flux in ischemia/reperfused brain regions and also to first sensitively detect 8-hydroxyl-2-deoxyguanosine in oxidatively damaged DNA and help assess its role in cancer development. We demonstrated that methylene blue (MB) photoinduces formation of 8-hydroxyguanine in DNA and RNA and discovered that MB sensitively photoinactivates RNA viruses, including HIV and the West Nile virus. Studies in experimental stroke led us serendipitously to discover that alpha-phenyl-tert-butylnitrone (PBN) was neuroprotective if given after the stroke. This led to extensive commercial development of NXY-059, a PBN derivative, for the treatment of stroke. More recently we discovered that PBN nitrones have potent anti-cancer activity and are active in preventing hearing loss caused by acute acoustical trauma. PMID:19439210

  11. DNP with Trityl Radicals in Deuterated Polyethylene

    NASA Astrophysics Data System (ADS)

    Wang, Li; Meyer, W.; Berlin, A.; Herick, J.; Hess, C.; Reicherz, G.

    2016-02-01

    Chemically doping with trityl radicals was performed in fully deuterated polyethylene. The behavior of paramagnetic centers has been investigated by ESR X-band spectrometer. The highest deuteron polarization was 8% at 2.5 T and 1 K with a spin concentration of 3 × 1019 spins/g.

  12. Unimolecular reaction dynamics of free radicals

    SciTech Connect

    Terry A. Miller

    2006-09-01

    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.

  13. Radical Constructivism, and the Sin of Relativism

    ERIC Educational Resources Information Center

    Quale, Andreas

    2007-01-01

    The epistemology of "relativism" that is featured by the theory of radical constructivism is addressed. In particular, I examine several objections, all based on this epistemic position of relativism, that are often raised by critics of the theory: the charge of "reality denial" (which, it is often claimed, must lead ultimately to the…

  14. Radical Feminism and the Subject of Writing.

    ERIC Educational Resources Information Center

    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…

  15. Density functional calculations on model tyrosyl radicals.

    PubMed Central

    Himo, F; Gräslund, A; Eriksson, L A

    1997-01-01

    A gradient-corrected density functional theory approach (PWP86) has been applied, together with large basis sets (IGLO-III), to investigate the structure and hyperfine properties of model tyrosyl free radicals. In nature, these radicals are observed in, e.g., the charge transfer pathways in photosystem II (PSII) and in ribonucleotide reductases (RNRs). By comparing spin density distributions and proton hyperfine couplings with experimental data, it is confirmed that the tyrosyl radicals present in the proteins are neutral. It is shown that hydrogen bonding to the phenoxyl oxygen atom, when present, causes a reduction in spin density on O and a corresponding increase on C4. Calculated proton hyperfine coupling constants for the beta-protons show that the alpha-carbon is rotated 75-80 degrees out of the plane of the ring in PSII and Salmonella typhimurium RNR, but only 20-30 degrees in, e.g., Escherichia coli, mouse, herpes simplex, and bacteriophage T4-induced RNRs. Furthermore, based on the present calculations, we have revised the empirical parameters used in the experimental determination of the oxygen spin density in the tyrosyl radical in E. coli RNR and of the ring carbon spin densities, from measured hyperfine coupling constants. Images FIGURE 1 FIGURE 5 PMID:9083661

  16. Dynamics of poly(4-hydroxystyrene) radical cation

    NASA Astrophysics Data System (ADS)

    Okamoto, Kazumasa; Kozawa, Takahiro; Tagawa, Seiichi

    2008-03-01

    Poly(4-hydroxystyrene) (PHS) has been used in KrF excimer laser (248 nm) lithography as a backbone polymer, and is also a promising material for EUV or electron beam lithography. Analysis of the intermediate species is important for the control of reactions in resist materials. Since the size of integrated circuits fabricated for mass production will decrease below 30 nm and the size error must also be decreased to the molecular level, the elucidation of proton dynamics at the molecular level is also important for reducing the deviation of the resist pattern size. In this study, the dynamics of PHS radical cations were studied, because PHS radical cation is main source of proton. The transient absorption of PHS was observed in the near-infrared region (NIR) in p-dioxane solutions by pulse radiolysis. The intramolecular PHS dimer radical cation (M2 +.) were observed, whereas p-cresol shows no distinct CR band. Although the radical cations of phenol derivatives are known to be easily deprotonated, it was found that M2 +. formation prevents deprotonation by its charge resonance stabilization.

  17. The Radical Faculty -- What Are Its Goals?

    ERIC Educational Resources Information Center

    Kampf, Louis

    According to radical faculty members and students, universities have been contradicting their humanistic educational ideals by concentrating on competitive professionalism and non-academic research in a struggle for institutional power in a preponderantly capitalistic society. It is their belief that meaningful education provides intellectual…

  18. Designed metalloprotein stabilizes a semiquinone radical.

    PubMed

    Ulas, Gözde; Lemmin, Thomas; Wu, Yibing; Gassner, George T; DeGrado, William F

    2016-04-01

    Enzymes use binding energy to stabilize their substrates in high-energy states that are otherwise inaccessible at ambient temperature. Here we show that a de novo designed Zn(II) metalloprotein stabilizes a chemically reactive organic radical that is otherwise unstable in aqueous media. The protein binds tightly to and stabilizes the radical semiquinone form of 3,5-di-tert-butylcatechol. Solution NMR spectroscopy in conjunction with molecular dynamics simulations show that the substrate binds in the active site pocket where it is stabilized by metal-ligand interactions as well as by burial of its hydrophobic groups. Spectrochemical redox titrations show that the protein stabilized the semiquinone by reducing the electrochemical midpoint potential for its formation via the one-electron oxidation of the catechol by approximately 400 mV (9 kcal mol(-1)). Therefore, the inherent chemical properties of the radical were changed drastically by harnessing its binding energy to the metalloprotein. This model sets the basis for designed enzymes with radical cofactors to tackle challenging chemistry. PMID:27001731

  19. Emerging themes in radical SAM chemistry

    PubMed Central

    Shisler, Krista A; Broderick, Joan B

    2014-01-01

    Enzymes in the radical SAM (RS) superfamily catalyze a wide variety of reactions through unique radical chemistry. The characteristic markers of the superfamily include a [4Fe–4S] cluster coordinated to the protein via a cysteine triad motif, typically CX3CX2C, with the fourth iron coordinated by S-adenosylmethionine (SAM). The SAM serves as a precursor for a 5′-deoxyadenosyl radical, the central intermediate in nearly all RS enzymes studied to date. The SAM-bound [4Fe–4S] cluster is located within a partial or full triosephosphate isomerase (TIM) barrel where the radical chemistry occurs protected from the surroundings. In addition to the TIM barrel and a RS [4Fe–4S] cluster, many members of the superfamily contain additional domains and/or additional Fe–S clusters. Recently characterized superfamily members are providing new examples of the remarkable range of reactions that can be catalyzed, as well as new structural and mechanistic insights into these fascinating reactions. PMID:23141873

  20. Neurotoxins: Free Radical Mechanisms and Melatonin Protection

    PubMed Central

    Reiter, Russel J.; Manchester, Lucien C.; Tan, Dun-Xian

    2010-01-01

    Toxins that pass through the blood-brain barrier put neurons and glia in peril. The damage inflicted is usually a consequence of the ability of these toxic agents to induce free radical generation within cells but especially at the level of the mitochondria. The elevated production of oxygen and nitrogen-based radicals and related non-radical products leads to the oxidation of essential macromolecules including lipids, proteins and DNA. The resultant damage is referred to as oxidative and nitrosative stress and, when the molecular destruction is sufficiently severe, it causes apoptosis or necrosis of neurons and glia. Loss of brain cells compromises the functions of the central nervous system expressed as motor, sensory and cognitive deficits and psychological alterations. In this survey we summarize the publications related to the following neurotoxins and the protective actions of melatonin: aminolevulinic acid, cyanide, domoic acid, kainic acid, metals, methamphetamine, polychlorinated biphenyls, rotenone, toluene and 6-hydroxydopamine. Given the potent direct free radical scavenging activities of melatonin and its metabolites, their ability to indirectly stimulate antioxidative enzymes and their efficacy in reducing electron leakage from mitochondria, it would be expected that these molecules would protect the brain from oxidative and nitrosative molecular mutilation. The studies summarized in this review indicate that this is indeed the case, an action that is obviously assisted by the fact that melatonin readily crosses the blood brain barrier. PMID:21358970