Free radical scavenging activity and neuroprotective potentials of D138, one Cu(II)/Zn(II) Schiff-base complex derived from N,N'-bis(2-hydroxynaphthylmethylidene)-1,3-propanediamine.

Science.gov (United States)

Wang, Che; Cai, Zheng-Xu; You, Zhong-Lu; Guo, Hui-Shu; Shang, De-Jing; Wang, Xiao-Ling; Zhang, Liang; Ma, Li-Jie; Tan, Jun; Le, Wei-Dong; Li, Song

2014-09-01

There is increasing evidence that free radicals play an important role in neuronal damages induced by diabetes mellitus or cerebral ischemia insults. Antioxidants with free radical scavenging activities have been shown to be beneficial and neuroprotective for these pathological conditions. Here, we report free radical scavenging activity and neuroprotective potential of D138, one copper(II)/zinc(II) Schiff-base complex derived from N,N'-2(2-hydroxynaphthylmethylidene)-1,3-propanediamine. The data from three in vitro assays, 2,2-diphenyl-1-picrylhydrazyl assay, nitro blue tetrazolium assay and hydroxyl radical scavenging assay, indicated that D138 presented a potent free radical scavenging activity. The neuroprotective and antioxidative effects of D138 were further evaluated in vivo using bilateral common carotid artery occlusion (BCCAO) mouse model and streptozotocin (STZ) diabetic mouse model. Our results indicated that treatment of D138 significantly ameliorated the hippocampal neuronal damage and the oxidative stress levels in these animal models. Moreover, D138 also reversed the behavioral deficiencies induced by BCCAO or STZ, as assessed by Y-maze test and fear conditioning test. In conclusion, all these findings support that D138 exerts free radical scavenging and neuroprotective activities and has the potentials to be a potent therapeutic candidate for brain oxidative damage induced by cerebral ischemia or diabetes mellitus.

Nickel induced re-structuring of 2D graphene to 1D graphene nanotubes: Role of radical hydrogen in catalyst assisted growth

Science.gov (United States)

Krishna, Rahul; Titus, Elby

2017-12-01

Here, we demonstrate for the first time the structural evolution of 1D graphene nanotubes (GNTs) by the cutting of two dimensional (2D) graphene oxide (GO) sheet in reducing environment at ambient conditions in presence of Ni metal in acidic environment. We observed that in-situ generated radical hydrogen (Hrad) responsible for cutting of graphene sheets and re-structuring of 2D sheet structure to one 1D nanotubes. Structural evolution of GNTs was confirmed by using of transmission electron microscopy (TEM) technique. The current vs. voltage (I-V) characteristics of GNTs displayed room temperature (RT) negative differential resistance (NDR) effect which is typical in nanowires, suggested the applicability of nanomaterial for various kind of electronics applications such as memory devices and transistors fabrication.

The influence of FLiNaK salt impregnation on the mechanical properties of a 2D woven C/C composite

Energy Technology Data Exchange (ETDEWEB)

Zhang, Dongsheng, E-mail: zhangdongsheng@sinap.ac.cn; Xia, Huihao; Yang, Xinmei, E-mail: yangxinmei@sinap.ac.cn; Feng, Shanglei; Song, Jinliang; Zhou, Xingtai

2017-03-15

Impregnating of molten LiF-NaF-KF salt (LiF-NaF-KF: 46.5–11.5-42 mol%, FLiNaK) into a 2D woven C/C composite was performed at 650 °C under different pressure. The weight gain and mechanical properties change of the 2D woven C/C composite after FLiNaK salt impregnation were measured. The FLiNaK salt distribution into the 2D woven C/C composite was observed by X-ray computed tomography (X-ray CT) and scanning electron microscopy. The results showed that the weight gain of the 2D woven C/C composite increased with increasing impregnating pressure. In X-ray CT images, FLiNaK salt was distributed into the open pores and fissures among fiber bundles and neighboring plies. The interlaminar shear strength, compressive strength, and flexural strength of the 2D woven C/C composite increased with the increase of weight gain. The influence of FLiNaK salt impregnation on the mechanical properties was attributed to the coupling effect of re-densification of FLiNaK salt impregnation and residual stress formed in 2D woven C/C composite. - Highlights: • FLiNaK salt was distributed into the open pores and fissures among fiber bundles. • The mechanical properties of the 2D woven C/C composite increased with the increase of weight gain. • The influence of FLiNaK was attributed to the re-densification of FLiNaK salt and residual stress.

Near resonant charge transfer in Na(4D)+K+ → Na++K*: Optical pumping of the Na(4D) state and energy dependence of rank 4 alignment

International Nuclear Information System (INIS)

Campbell, E.E.B.; Huelser, H.; Witte, R.; Hertel, I.V.

1990-01-01

Rank 4 alignment has been observed in a quasi one electron system. Relative charge transfer cross sections of the Na 4dσ, 4dπ and 4dδ sublevels for the K + +Na(4D)→K * +Na + system have been measured. A strong energy dependence is observed. The results at energies less than 1 keV may be attributed to rotational coupling of the Na 4dπ state to the K 4fδ state. The Na atom is excited in a two-step process, the first step being excitation to the 3 2 P 3/2 level with a two-mode laser to pump from both hyperfine levels of the ground state simultaneously. This two-mode laser is described in detail. The optical pumping problem is solved using rate equations. The general formula for describing the scattering intensity for cylindrical symmetry, in terms of multipole moments, for atoms excited by two linearly polarised lasers is derived and used to evaluate the experimental results. (orig.)

Composition and thermochemistry of the equilibrium vapour of the systems NaI-FeI2 and NaI-PbI2

International Nuclear Information System (INIS)

Hilpert, K.; Gerads, H.; Koberts, D.; Miller, M.

1987-01-01

The vaporization of NaI/FeI 2 and NaI/PbI 2 samples of equimolar composition was investigated was investigated in the temperature ranges between 574 to 683 K and 562 to 669 K, respectively, by using the mass spectrometric Knudsen effusion method. The gaseous species I, I 2 , NaI, (NaI) 2 , FeI 2 , (FeI 2 ) 2 , FeI 3 , NaFeI 3 , and Na 2 FeI 4 (NaI-FeI 2 system) as well as NaI, (NaI) 2 , PbI 2 , (PbI 2 ) 2 , and NaPbI 3 (NaI-PbI 2 system) are present in the equilibrium vapours. The equilibrium partial pressures of these species were determined with the exception of I, I 2 , and FeI 3 . Enthalpies and entropies of dissociation resulted for the reactions NaFeI 3 (g) ↔ NaI(g)+FeI 2 (g) (1), Na 2 FeI 4 (g) ↔ 2NaI(g)+FeI 2 (g) and (2) NaPbI 3 (g) ↔ NaI(g)+PbI 2 (g) (3) as Δ d H 298 0 (Eq. (1)) = 184±5 kJ mol -1 , Δ d S 298 0 (Eq. (1)) = 143±8 J mol -1 K -1 ; Δ d H 298 0 (Eq. (2)) = 333±9 kJ mol -1 , Δ d S 298 0 (Eq. (2)) = 274±14 J mol -1 K -1 ; and Δ d H 298 0 (Eq. (3)) = 168±5 kJ mol -1 , Δ d S 298 0 (Eq. (3)) = 151±9 J mol -1 K -1 . Equilibrium constants for these reactions are additionally given. The pressures of NaFeI 3 (g) and NaPbI 3 (g) as all as their enthalpies of dissociation are discussed with respect to their significance of semi empirical rules. (orig.)

Detection of Anisotropic Hyperfine Components of Chemically Prepared Carotenoid Radical Cations:1D and 2D ESEEM and Pulsed ENDOR Study

International Nuclear Information System (INIS)

Konovalova, Tatyana A.; Dikanov, Sergei A.; Bowman, Michael K.; Kispert, Lowell D.

2001-01-01

Canthaxanthin and 8'-apo-B-caroten-8'-al radical cations chemically prepared on activated silica-alumina and in CH2CI2 solution containing A1C13 were studied by pulsed EPR and ENDOR spectroscopies. Both the 1D three-pulse ESEEM and the 2D HYSCORE spectra of the carotenoid-A1C13 mixtures exhibited the 27 A1 nuclei peak at 3.75 MHz. This indicates electron-transfer interactions between carotenoids and A1III ions resulting in the formation and stabilization of carotenoid radical cations. Davies ENDOR measurements of the canthaxanthin radical cation on silica-alumina determined the hyperfine couplings of B protons belonging to three different methyl groups with ahI=2.6 MHz, aH2=8.6MHz, and ah3 ca. 13 MHz. The principal components of the proton hyperfine tensors were obtained from HYSCORE spectra in A1C13 solutions and on the solid support. Identification of the protons was made on the basis of isotropic hyperfine couplings determined by RHF-INDO/SP molecular orbital calculations. In frozen A1C13 solution, the C(7, 7')Ha and C(14, 14')-Ha a protons were observed for Canthaxanthin and the C(8 or 14')-Ha, C(15')-Ha were observed for 8'-apo-B-caroten-8'-al. On the silica-alumina support, the C(10, 10')-Ha, C(11, 11')-Ha, and C(15,15')-Ha a protons were measured for Canthaxanthin and the C(12)-Ha and C(15')-Ha were measured for 8' apo-B-caroten-8'-al. Some protons with large isotropic couplings (> 10 MHz) determined from HYSCORE analysis could be assigned to B protons, but the principal components of their hyperfine tensors are much more anisotropic than those reported previously for B protons. We suggest that cis/trans isomerization of carotenoids on silica-alumina results in stabilization of di-cis isomers with large isotropic couplings for some a protons which are comparable to those of B protons

INFLUÊNCIA DA MATÉRIA ORGÂNICA NA BIODEGRADAÇÃO DO ÁCIDO 2,4-DICLOROFENOXIACÉTICO (2,4-D

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Ida Carolina Neves Direito

2015-07-01

Full Text Available O herbicida ácido 2,4-diclorofenoxiacético (2,4-D é um dos mais utilizados no mundo e pode causar prejuízos ao meio ambiente e à saúde humana. Os microrganismos do solo tem importante função na degradação de compostos químicos como os pesticidas. A matéria orgânica, como adubos orgânicos e metabólitos secundários vegetais, podem estimular os microrganismos do solo. Dentre os metabólitos secundários vegetais, existem os flavonóides. O processo de degradação de flavonóides pode resultar no ácido protocatecóico, o qual é um intermediário na rota de degradação de pesticidas aromáticos, como o 2,4-D.  Este estudo investigou a influência da matéria orgânica na biodegradação do 2,4-D. Em um primeiro momento, analizamos a capacidade de crescimento de isolados bacterianos, que podem utilizar 2,4-D como única fonte de carbono, na presença de biopirol, quercetina e rutina. Em seguida, verificamos a influência destas moléculas orgânicas sobre a comunidade microbiana do solo com histórico de aplicação do 2,4-D. Os resultados mostraram que os isolados bacterianos são capazes de utilizar pelo menos um dos modelos de matéria orgânica empregados. Os resultados gerados no experimento conduzido para verificar a influencia da matéria orgânica sobre a comunidade microbiana e a degradação do 2,4-D sugere que a associação do 2,4-D com a matéria orgânica poderia ampliar a persistência deste no ambiente, ou poderia representar um estádio de adaptação dos microrganismos do solo. Nossos resultados sugerem que o efeito de resíduos orgânicos na biodegradação do 2,4-D tem potencial biotecnológico.

Uptake Coefficients of NO3 Radicals on Solid Surfaces of Sea-Salts

Science.gov (United States)

Gratpanche, F.; Sawerysyn, J.-P.

1999-02-01

Uptake coefficients of nitrate radicals (γ NO_3) have been measured by a technique involving a coated-wall flow tube with radical detection by E.P.R. spectrometry. The variation of NO3 concentration in the gas phase was followed indirectly by monitoring OH radicals produced by the titration reaction H + NO_3. The mean initial value of γ NO3 measured on solid NaCl surfaces was (1.7± 1.2)× 10-2) in the temperature range 258-301 K, while for solid NaBr surfaces the value was (0.11 ± 0.06) at 293 K. In each case, errors limits correspond to one standard deviation. For NaBr, a slight negative temperature dependence was observed over the investigated range, 243-293 K, which can be represented by γ_NO_3^NaBr = 1.6 ≤ft(begin{array}{l}+1.8 -0.9) × 10-3exp [(1210± 200)/T]. An analysis of the results shows that under some conditions the heterogeneous loss of nitrate radicals on sea-salt aerosol particles at ambient temperature could be competitive with their loss by homogeneous reaction in the marine troposphere at night. Les coefficients de capture des radicaux nitrate (γ NO_3) sur des surfaces de sels marins (NaCl et NaBr) ont été mesurés aux températures troposphériques en utilisant la technique du réacteur à écoulement à paroi recouverte couplée à un spectromètre de résonance paramagnétique électronique (R.P.E). La variation de la concentration en phase gazeuse des radicaux nitrate en présence des surfaces étudiées est suivie en mesurant le signal R.P.E des radicaux OH produits par la réaction de titrage H + NO3. Pour des températures comprises entre 258 et 301 K, la valeur moyenne du coefficient de capture initial (γ NO_3) sur des surfaces solides de NaCl est égal à (1.7± 1.2)× 10-2). Sur des surfaces solides de NaBr, (γ NO_3) est égal à (0.11 ± 0.06) à 293 K. L'incertitude correspond à une déviation standard. Par ailleurs, pour ce type de surfaces, une légère dépendance négative avec la température est observée dans la

Simultaneous catalytic degradation of 2,4-D and MCPA herbicides using sulfate radical-based heterogeneous oxidation over persulfate activated by natural hematite (α-Fe2O3/PS)

Science.gov (United States)

Kermani, Majid; Mohammadi, Farzad; Kakavandi, Babak; Esrafili, Ali; Rostamifasih, Zeinab

2018-06-01

Herein, a sulfate radical (SO4rad -)-based oxidation process was utilized for simultaneous degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA) herbicides using mesoporous hematite-based natural semi-conductor minerals (HM-NSMs) as efficient activators of persulfate (PS). The features of the catalyst were characterized using field emission scanning electron microscopy (FESEM); Brunauer, Emmett and Teller (BET) analysis; X-ray diffraction (XRD); and energy-dispersive X-ray spectroscopy (EDS). The effect of some operational parameters, including solution pH, catalyst loading, PS dosage and temperature, on the performance system of PS/HM-NSMs was examined. A plausible oxidation mechanism for degradation of both pollutants was also proposed. Increasing the removal efficiency of herbicides follows the order of PS/HM-NSM > HM-NSM > PS. In all experiments, the 2,4-D removal rates were slightly lower than those for MCPA, indicating that 2,4-D has a more recalcitrant nature than MCPA. Under optimized conditions, degradation rates of 68.1% and 74.5% were achieved for 2,4-D and MCPA, respectively, during a 120-min reaction. HM-NSM displays a highly synergistic effect on the degradation of herbicides in the presence of PS. The trapping experiments demonstrated that both OHrad and SO4rad - radicals contribute significantly during the degradation of 2,4-D and MCPA and that sulfate radicals were the dominant species. A mineralization degree of 36% was obtained under optimum conditions. In conclusion, the coupling of PS and HM-NSM is a promising and effective technique to degrade organic matter for the treatment of herbicide-contaminated waters and wastewaters under real conditions.

Synthesis of 2-iodobenzamides and 3-(iodoacetamide)benzamides linked to D-galactose and their tri-n-butyltin hydride-mediated radical carbocyclization reactions

International Nuclear Information System (INIS)

Leal, Daniel Henriques Soares; Queiroga, Carla Graziella; Pires, Magno Carvalho; Prado, Maria Auxiliadra Fontes; Alves, Ricardo Jose; Cesar, Amary

2009-01-01

Starting from methyl 6-O-allyl-4-azido-2,3-di-O-benzyl-4-deoxy-a-D-galactopyranoside, four new derivatives containing 2-iodobenzamide and 3-(iodoacetamide)benzamido groups were synthesized. These four compounds were submitted to tri-n-butyltin hydride mediated radical cyclization reactions, resulting in two macrolactams from 11- and 15-endo aryl radical cyclization. The corresponding four hydrogenolysis products were also obtained. The structures of the new compounds were elucidated by 1 H and 13 C NMR spectroscopy, DEPT, COSY, HMQC and HMBC experiments. (author)

Photoactivation of isoflavonoid phytoalexins: involvement of free radicals

International Nuclear Information System (INIS)

Bakker, J.; Gommers, F.J.; Smits, L.; Fuchs, A.; Vries, F.W. de

1983-01-01

Ultraviolet irradiation of isoflavonoid phytoalexins phaseollin, 3.6a. 9-trihydroxypterocarpan, glyceollin, tuberosin and pisatin, but not medicarpin, brought about inactivation of glucose-6-phosphate dehydrogenase in an in vitro assay system. Photoinactivation of the enzyme by photoactivated pisatin in air-saturated solutions was hardly affected by singlet oxygen quenchers such as NaN 3 , bovine serum albumin, histidine or methionine. Neither addition of the hydroxyl radical scavengers mannitol, Na-benzoate and ethanol nor the presence of catalase or superoxide dismutase protected the enzyme against photoinactivation, suggesting that OHradical, H 2 O 2 and O 2 radical are not the reactive oxygen species involved. However, the free radical scavenger S-(2-amino-ethyl)isothiouronium bromide hydrobromide (AET) protected the enzyme against inactivation by photoactivated pisatin. Direct evidence for the generation of free radicals was obtained by ESR measurements of solutions of phaseollin, pisatin and medicarpin in hexane irradiated with ultraviolet light in the presence or absence of O 2 . Phaseollin produced the most stable free radicals, whereas medicarpin hardly gave rise to free radical formation; pisatin took a somewhat intermediate position by producing a strong ESR signal which, however, decayed rather quickly. These results indicate free radical formation as the cause for photoinactivation of enzymes by photoactivated isoflavonoid phytoalexins. (author)

ESR study of the anion radicals of 5-nitropyrimidines: conversion to iminoxy radicals

International Nuclear Information System (INIS)

Sevilla, M.D.; Clark, C.; Failor, R.

1976-01-01

The anion radicals of a number of 5-nitropyrimidines have been investigated by ESR spectroscopy. The anions are formed by electrolysis in dimethylformamide and by electron attachment in aqueous glasses, 12 M LiCl--D 2 O and 8 M NaOD. The electrolysis of 5-nitrouracil and 5-nitro-6-methyluracil results in relatively stable anion radicals. The results for 5-nitrouracil give evidence for two or perhaps three anions which differ only by the degree of ring nitrogen protonation. The results for 5-nitro-6-methyluracil suggest that the nitro group of the anion is twisted so that it is coupled only weakly to the ring π-electron system. The anions of 5-nitrouracil, 5-nitroorotic acid, 5-nitrobarbituric acid, and 5-nitro-6-methyluracil have been produced in the alkaline and neutral aqueous glasses. The anisotropic spectra found have been analyzed with the aid of computer simulations which assume axial symmetry. For example, the analysis of the spectrum of 5-nitrouracil anion in 12 M LiCl yields A/sub parallel//sup N/ = 33; A/sub perpendicular to//sup N/ = 5, a 6 /sup H/ = 5.5 G, g/sub parallel/ = 2.0016, and g/sub perpendicular to/ = 2.0059. A concentration dependence in the splittings is noted and discussed. Ultraviolet photolysis of the anions of 5-nitro-6-methyluracil and 5-nitrobarbituric acid results in the formation of iminoxy radicals. Mechanisms of formation of the iminoxy radicals are discussed and results found in this work are compared to results found in single crystals and aqueous solution

EPR Spectroscopy of Radical Ions of a 2,3-Diamino-1,4-naphthoquinone Derivative.

Science.gov (United States)

Tarábek, Ján; Wen, Jin; Dron, Paul I; Pospíšil, Lubomír; Michl, Josef

2018-05-18

We report the electron paramagnetic resonance spectra of the radical cation and radical anion of 1,2,2,3-tetramethyl-2,3-dihydro-1 H-naphtho[2,3- d]imidazole-4,9-dione (1) and its doubly 13 C labeled analogue 2, of interest for singlet fission. The hyperfine coupling constants are in excellent agreement with density functional theory calculations and establish the structures beyond doubt. Unlike the radical cation 1 •+ , the radical anion 1 •- and its parent 1 have pyramidalized nitrogen atoms and inequivalent methyl groups 15 and 16, in agreement with the calculations. The distinction is particularly clear with the labeled analogue 2 •- .

Dynamic polarizabilities and Van der Waals coefficients for alkali atoms Li, Na and alkali dimer molecules Li2, Na2 and NaLi

Science.gov (United States)

Mérawa, M.; Dargelos, A.

1998-07-01

The present paper gives an account of investigations of the polarizability of the alkali atoms Li, Na, diatomics homonuclear and heteronuclear Li2, Na2 and NaLi at SCF (Self Consistent Field) level of approximation and at correlated level, using a time Time-Dependent Gauge Invariant method (TDGI). Our static polarizability values agree with the best experimental and theoretical determinations. The Van der Waals C6 coefficients for the atom-atom, atom-dimer and dimer-dimer interactions have been evaluated. Les polarisabilités des atomes alcalins Li, Na, et des molécules diatomiques homonucléaires et hétéronucléaire Li2, Na2 et NaLi, ont été calculées au niveau SCF (Self Consistent Field) et au niveau corrélé à partir d'une méthode invariante de jauge dépendante du temps(TDGI). Nos valeurs des polarisabilités statiques sont en accord avec les meilleurs déterminations expérimentales et théoriques. Les coefficients C6 de Van de Waals pour les interactions atome-atome, atome-dimère et dimère-dimère ont également été évalués.

OH radicals distribution in an Ar-H2O atmospheric plasma jet

Science.gov (United States)

Li, L.; Nikiforov, A.; Xiong, Q.; Britun, N.; Snyders, R.; Lu, X.; Leys, C.

2013-09-01

Recently, plasma jet systems found numerous applications in the field of biomedicine and treatment of temperature-sensitive materials. OH radicals are one of the main active species produced by these plasmas. Present study deals with the investigation of RF atmospheric pressure plasma jet in terms of OH radicals production by admixture of H2O into argon used as a feed gas. Generation of OH radicals is studied by laser-induced fluorescence spectroscopy. The excitation dynamics of OH radicals induced by the laser photons is studied by time-resolved spectroscopy. It is shown that vibrational and rotational energy transfer processes, which are sensitive to the surrounding species, can lead to the complication in the OH radicals diagnostics at high pressure and have to be considered during experiments. The axial and radial 2D maps of absolute densities of hydroxyl radicals at different water contents are obtained. The highest density of 1.15 × 1020 m-3 is measured in the plasma core for the case of 0.3% H2O. In the x-y-plane, the OH density steeply decreases within a range of ±2 mm from its maximum value down to 1018 m-3. The effect of H2O addition on the generation of OH radicals is investigated and discussed.

Differential and integral cross sections for the rotationally inelastic scattering of methyl radicals with H2 and D2

International Nuclear Information System (INIS)

Tkáč, Ondřej; Orr-Ewing, Andrew J.; Ma, Qianli; Dagdigian, Paul J.; Rusher, Cassandra A.; Greaves, Stuart J.

2014-01-01

Comparisons are presented of experimental and theoretical studies of the rotationally inelastic scattering of CD 3 radicals with H 2 and D 2 collision partners at respective collision energies of 680 ± 75 and 640 ± 60 cm −1 . Close-coupling quantum-mechanical calculations performed using a newly constructed ab initio potential energy surface (PES) provide initial-to-final CD 3 rotational level (n, k → n′, k′) integral and differential cross sections (ICSs and DCSs). The DCSs are compared with crossed molecular beam and velocity map imaging measurements of angular scattering distributions, which serve as a critical test of the accuracy of the new PES. In general, there is very good agreement between the experimental measurements and the calculations. The DCSs for CD 3 scattering from both H 2 and D 2 peak in the forward hemisphere for n′ = 2–4 and shift more to sideways and backward scattering for n′ = 5. For n′ = 6–8, the DCSs are dominated by backward scattering. DCSs for a particular CD 3 n → n′ transition have a similar angular dependence with either D 2 or H 2 as collision partner. Any differences between DCSs or ICSs can be attributed to mass effects because the PES is unchanged for CD 3 −H 2 and CD 3 –D 2 collisions. Further comparisons are drawn between the CD 3 –D 2 scattering and results for CD 3 –He presented in our recent paper [O. Tkáč, A. G. Sage, S. J. Greaves, A. J. Orr-Ewing, P. J. Dagdigian, Q. Ma, and M. H. Alexander, Chem. Sci. 4, 4199 (2013)]. These systems have the same reduced mass, but are governed by different PESs

Why Nature Uses Radical SAM Enzymes so Widely: Electron Nuclear Double Resonance Studies of Lysine 2,3-Aminomutase Show the 5′-dAdo• “Free Radical” Is Never Free

Science.gov (United States)

Horitani, Masaki; Byer, Amanda S.; Shisler, Krista A.; Chandra, Tilak; Broderick, Joan B.; Hoffman, Brian M.

2015-01-01

Lysine 2,3-aminomutase (LAM) is a radical S-adenosyl-L-methionine (SAM) enzyme and, like other members of this superfamily, LAM utilizes radical-generating machinery comprising SAM anchored to the unique Fe of a [4Fe-4S] cluster via a classical five-membered N,O chelate ring. Catalysis is initiated by reductive cleavage of the SAM S–C5′ bond, which creates the highly reactive 5′-deoxyadenosyl radical (5′-dAdo•), the same radical generated by homolytic Co–C bond cleavage in B12 radical enzymes. The SAM surrogate S-3′,4′-anhydroadenosyl-L-methionine (anSAM) can replace SAM as a cofactor in the isomerization of L-α-lysine to L-β-lysine by LAM, via the stable allylic anhydroadenosyl radical (anAdo•). Here electron nuclear double resonance (ENDOR) spectroscopy of the anAdo• radical in the presence of 13C, 2H, and 15N-labeled lysine completes the picture of how the active site of LAM from Clostridium subterminale SB4 “tames” the 5′-dAdo• radical, preventing it from carrying out harmful side reactions: this “free radical” in LAM is never free. The low steric demands of the radical-generating [4Fe-4S]/SAM construct allow the substrate target to bind adjacent to the S–C5′ bond, thereby enabling the 5′-dAdo• radical created by cleavage of this bond to react with its partners by undergoing small motions, ~0.6 Å toward the target and ~1.5 Å overall, that are controlled by tight van der Waals contact with its partners. We suggest that the accessibility to substrate and ready control of the reactive C5′ radical, with “van der Waals control” of small motions throughout the catalytic cycle, is common within the radical SAM enzyme superfamily and is a major reason why these enzymes are the preferred means of initiating radical reactions in nature. PMID:25923449

Correlation between inter-spin interaction and molecular dynamics of organic radicals in organic 1D nanochannels

Energy Technology Data Exchange (ETDEWEB)

Kobayashi, Hirokazu [Department of Chemistry, College of Humanities and Sciences, Nihon University 3-25-40, Sakura-jo-sui, Setagaya-ku, Tokyo, 156-8550 (Japan)

2015-12-31

One-dimensional (1D) molecular chains of 4-substituted-2,2,6,6-tetramethyl-1-piperidinyloxyl (4-X-TEMPO) radicals were constructed in the crystalline 1D nanochannels of 2,4,6-tris(4-chlorophenoxy)-1,3,5-triazine (CLPOT) used as a template. The ESR spectra of CLPOT inclusion compounds (ICs) using 4-X-TEMPO were examined on the basis of spectral simulation using EasySpin program package for simulating and fitting ESR spectra. The ESR spectra of [(CLPOT){sub 2}-(TEMPO){sub 1.0}] IC were isotropic in the total range of temperatures. The peak-to-peak line width (ΔB{sub pp}) became monotonically narrower from 2.8 to 1.3 mT with increase in temperature in the range of 4.2–298 K. The effect of the rotational diffusion motion of TEMPO radicals in the CLPOT nanochannels for the inter-spin interaction of the [(CLPOT){sub 2}-(TEMPO){sub 1.0}] IC was found to be smaller than the case of [(TPP){sub 2}−(TEMPO){sub 1.0}] IC (TPP = tris(o-phenylenedioxy)cyclotriphosphazene) reported in our previous study. The ΔB{sub pp} of the [(CLPOT){sub 2}-(TEMPO){sub 1.0}] IC in the whole range of temperatures was much narrower than the estimation to be based on the Van Vleck’s formula for the second moment of the rigid lattice model where the electron spin can be considered as fixed; 11 mT of Gaussian line-width component. This suggests the possibility of exchange narrowing in the 1D organic-radical chains of the [(CLPOT){sub 2}-(TEMPO){sub 1.0}] IC. On the other hand, the ESR spectra of [(CLPOT){sub 2}-(MeO-TEMPO){sub 0.41}] IC (MeO-TEMPO = 4-methoxy-TEMPO) were reproduced by a superposition of major broad isotropic adsorption line and minor temperature-dependent modulated triplet component. This suggests that the IC has the part of 1D organic-radical chains and MeO-TEMPO molecules isolated in the CLPOT nanochannels.

New derivatives of 3,4-dihydroisoquinoline-3-carboxylic acid with free-radical scavenging, D-amino acid oxidase, acetylcholinesterase and butyrylcholinesterase inhibitory activity.

Science.gov (United States)

Solecka, Jolanta; Guśpiel, Adam; Postek, Magdalena; Ziemska, Joanna; Kawęcki, Robert; Lęczycka, Katarzyna; Osior, Agnieszka; Pietrzak, Bartłomiej; Pypowski, Krzysztof; Wyrzykowska, Agata

2014-09-30

A series of 3,4-dihydroisoquinoline-3-carboxylic acid derivatives were synthesised and tested for their free-radical scavenging activity using 2,2-diphenyl-1-picrylhydrazyl radical (DPPH·), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS·+), superoxide anion radical (O2·-) and nitric oxide radical (·NO) assays. We also studied d-amino acid oxidase (DAAO), acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory activity. Almost each of newly synthesised compounds exhibited radical scavenging capabilities. Moreover, several compounds showed moderate inhibitory activities against DAAO, AChE and BuChE. Compounds with significant free-radical scavenging activity may be potential candidates for therapeutics used in oxidative-stress-related diseases.

Atmospheric hydroxyl radical production from electronically excited NO2 and H2O.

Science.gov (United States)

Li, Shuping; Matthews, Jamie; Sinha, Amitabha

2008-03-21

Hydroxyl radicals are often called the "detergent" of the atmosphere because they control the atmosphere's capacity to cleanse itself of pollutants. Here, we show that the reaction of electronically excited nitrogen dioxide with water can be an important source of tropospheric hydroxyl radicals. Using measured rate data, along with available solar flux and atmospheric mixing ratios, we demonstrate that the tropospheric hydroxyl contribution from this source can be a substantial fraction (50%) of that from the traditional O(1D) + H2O reaction in the boundary-layer region for high solar zenith angles. Inclusion of this chemistry is expected to affect modeling of urban air quality, where the interactions of sunlight with emitted NOx species, volatile organic compounds, and hydroxyl radicals are central in determining the rate of ozone formation.

Electrochemical treatment of 2, 4-dichlorophenol using a nanostructured 3D-porous Ti/Sb-SnO2-Gr anode: Reaction kinetics, mechanism, and continuous operation.

Science.gov (United States)

Asim, Sumreen; Zhu, Yunqing; Batool, Aisha; Hailili, Reshalaiti; Luo, Jianmin; Wang, Yuanhao; Wang, Chuanyi

2017-10-01

2, 4-dichlorophenol (2, 4-DCP) is considered to be a highly toxic, mutagenic, and possibly carcinogenic pollutant. This study is focused on the electrochemical oxidation of 2, 4-DCP on nanostructured 3D-porous Ti/Sb-SnO 2 -Gr anodes, with the aim of presenting a comprehensive elucidation of mineralization process through the investigation of influential kinetics, the reactivity of hydroxyl radical's and analysis of intermediates. High efficiency was achieved at pH of 3 using Na 2 SO 4 electrolytes at a current density of 30 mA cm -2 . Under the optimized conditions, a maximum removal of 2, 4-DCP of up to 99.9% was reached, whereas a TOC removal of 81% was recorded with the lowest EC TOC (0.49 kW h g -1 ) within 40 min of electrolysis. To explore the stability of the 3D-Ti/Sb-SnO 2 -Gr electrodes, a continuous electrochemical operation was established, and the consistent mineralization results indicated the effectiveness of the 3D-Ti/Sb-SnO 2 -Gr system concerning its durability and practical utilization. EPR studies demonstrated the abundant generation of OH radicals on 3D-Ti/Sb-SnO 2 -Gr, resulting in fast recalcitrant pollutant incineration. From dechlorination and the reactivity of the OH radicals, several intermediates including six cyclic byproducts and three aliphatic carboxylic acids were detected, and two possible degradation pathways were proposed that justify the complete mineralization of 2, 4-DCP. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of He pressure on the superconducting transition temperatures of Na2CsC60 and (NH3)4Na2CsC60

International Nuclear Information System (INIS)

Schirber, J.E.; Bayless, W.R.; Rosseinsky, M.J.; Zhou, O.; Fleming, R.M.; Murphy, D.; Fischer, J.E.

1994-01-01

The Na based mixed alkali doped C 60 superconductors show anomalous behavior with respect to the ''universal'' superconducting transition temperature T c vs lattice constant a 0 relation followed by most of the fcc A 3 C 60 superconductors. We have measured dt c /dP for Na 2 CsC 60 and (NH 3 ) 4 Na 2 CsC 60 using solid He as the pressure medium to ∼ 6 kbar finding dT c /dP equal to -0.8±(0.01) K/kbar and -1.0(±0.1)K/kbar for Na 2 CsC 60 and Na 2 (NH 3 ) 4 C 60 respectively. Our value for Na 2 CsC 60 differs markedly from that obtained by Mizuki et al of about -1.3 K/kbar. However, using N 2 or Ar, we obtain values for dT c /dP in substantial agreement with Mizuki et al who used fluorinert to generate their pressure. This work emphasizes the need for compressibility measurements with the same pressure medium in the appropriate temperature range so that meaningful comparisons can be made between various pressure measurements and models which are based on lattic spacing

Reaction of Br/sub 3/. /sup 2 -/ with 2-deoxy-D-ribose. A preferred attack at C-1

Energy Technology Data Exchange (ETDEWEB)

Parsons, B J; Schulte-Frohlinde, D; von Sonntag, C [Max-Planck-Institut fuer Kohlenforschung, Muelheim an der Ruhr (Germany, F.R.). Inst. fuer Strahlenchemie

1978-06-01

In the photolysis of 5-bromouracil containing DNA Br atoms are expected intermediates. In order to evaluate the possible site of attack of the Br atom at the sugar moiety of DNA the reaction of 2-deoxy-D-Ribose with the Br atom (complexed with two bromide ions) was investigated. Hydroxyl radicals generated by the radiolysis of N/sub 2/O saturated aqueous solutions were converted into Br/sub 3/./sup 2 -/-radicals by 1 M bromide ions. Br/sub 3/./sup 2 -/-reacts with 2-deoxy-D-ribose (k = 3.7 x 10/sup 4/M/sup -1/s/sup -1/, pulse radiolysis). The major product is 2-deoxy-D-erythro-pentonic acid (G = 2.4, ..gamma..-radiolysis). It is formed by hydrogen abstraction from C-1 and oxidation of this radical by other radicals. An alternative route via the radical at C-2 is neglible. It follows that Br/sub 3/./sup 2 -/ reacts preferentially at C-1 of 2-deoxy-D-ribose.

Borophane as a Benchmate of Graphene: A Potential 2D Material for Anode of Li and Na-Ion Batteries.

Science.gov (United States)

Jena, Naresh K; Araujo, Rafael B; Shukla, Vivekanand; Ahuja, Rajeev

2017-05-17

Borophene, single atomic-layer sheet of boron ( Science 2015 , 350 , 1513 ), is a rather new entrant into the burgeoning class of 2D materials. Borophene exhibits anisotropic metallic properties whereas its hydrogenated counterpart borophane is reported to be a gapless Dirac material lying on the same bench with the celebrated graphene. Interestingly, this transition of borophane also rendered stability to it considering the fact that borophene was synthesized under ultrahigh vacuum conditions on a metallic (Ag) substrate. On the basis of first-principles density functional theory computations, we have investigated the possibilities of borophane as a potential Li/Na-ion battery anode material. We obtained a binding energy of -2.58 (-1.08 eV) eV for Li (Na)-adatom on borophane and Bader charge analysis revealed that Li(Na) atom exists in Li + (Na + ) state. Further, on binding with Li/Na, borophane exhibited metallic properties as evidenced by the electronic band structure. We found that diffusion pathways for Li/Na on the borophane surface are anisotropic with x direction being the favorable one with a barrier of 0.27 and 0.09 eV, respectively. While assessing the Li-ion anode performance, we estimated that the maximum Li content is Li 0.445 B 2 H 2 , which gives rises to a material with a maximum theoretical specific capacity of 504 mAh/g together with an average voltage of 0.43 V versus Li/Li + . Likewise, for Na-ion the maximum theoretical capacity and average voltage were estimated to be 504 mAh/g and 0.03 V versus Na/Na + , respectively. These findings unambiguously suggest that borophane can be a potential addition to the map of Li and Na-ion anode materials and can rival some of the recently reported 2D materials including graphene.

OH radicals distribution in an Ar-H{sub 2}O atmospheric plasma jet

Energy Technology Data Exchange (ETDEWEB)

Li, L.; Leys, C. [Department of Applied Physics, Research Unit Plasma Technology, Ghent University, Sint-Pietersnieuwstraat 41, Ghent B-9000 (Belgium); Nikiforov, A. [Department of Applied Physics, Research Unit Plasma Technology, Ghent University, Sint-Pietersnieuwstraat 41, Ghent B-9000 (Belgium); Institute of Solution Chemistry of the Russian Academy of Sciences, Academicheskaya St., 1, Ivanono, 153045 (Russian Federation); Xiong, Q. [Department of Applied Physics, Research Unit Plasma Technology, Ghent University, Sint-Pietersnieuwstraat 41, Ghent B-9000 (Belgium); College of Electrical and Electronic Engineering, HuaZhong University of Science and Technology, WuHan, Hubei 430074 (China); Britun, N. [Chimie des Interactions Plasma-Surface (ChIPS), CIRMAP, Universite de Mons, 20 Place du Parc, B-7000 Mons (Belgium); Snyders, R. [Chimie des Interactions Plasma-Surface (ChIPS), CIRMAP, Universite de Mons, 20 Place du Parc, B-7000 Mons (Belgium); Materia Nova Research Centre, Parc Initialis, B-7000 Mons (Belgium); Lu, X. [College of Electrical and Electronic Engineering, HuaZhong University of Science and Technology, WuHan, Hubei 430074 (China)

2013-09-15

Recently, plasma jet systems found numerous applications in the field of biomedicine and treatment of temperature-sensitive materials. OH radicals are one of the main active species produced by these plasmas. Present study deals with the investigation of RF atmospheric pressure plasma jet in terms of OH radicals production by admixture of H{sub 2}O into argon used as a feed gas. Generation of OH radicals is studied by laser-induced fluorescence spectroscopy. The excitation dynamics of OH radicals induced by the laser photons is studied by time-resolved spectroscopy. It is shown that vibrational and rotational energy transfer processes, which are sensitive to the surrounding species, can lead to the complication in the OH radicals diagnostics at high pressure and have to be considered during experiments. The axial and radial 2D maps of absolute densities of hydroxyl radicals at different water contents are obtained. The highest density of 1.15 × 10{sup 20} m{sup −3} is measured in the plasma core for the case of 0.3% H{sub 2}O. In the x–y-plane, the OH density steeply decreases within a range of ±2 mm from its maximum value down to 10{sup 18} m{sup −3}. The effect of H{sub 2}O addition on the generation of OH radicals is investigated and discussed.

Thermochemistry and kinetics for 2-butanone-1-yl radical (CH2·C(═O)CH2CH3) reactions with O2.

Science.gov (United States)

Sebbar, N; Bozzelli, J W; Bockhorn, H

2014-01-09

Thermochemistry of reactants, intermediates, transition state structures, and products along with kinetics on the association of CH2·C(═O)CH2CH3 (2-butanone-1-yl) with O2 and dissociation of the peroxy adduct isomers are studied. Thermochemical properties are determined using ab initio (G3MP2B3 and G3) composite methods along with density functional theory (B3LYP/6-311g(d,p)). Entropy and heat capacity contributions versus temperature are determined from structures, vibration frequencies, and internal rotor potentials. The CH2·C(═O)CH2CH3 radical + O2 association results in a chemically activated peroxy radical with 27 kcal mol(-1) excess of energy. The chemically activated adduct can react to stabilized peroxy or hydroperoxide alkyl radical adducts, further react to lactones plus hydroxyl radical, or form olefinic ketones and a hydroperoxy radical. Kinetic parameters are determined from the G3 composite methods derived thermochemical parameters, and quantum Rice-Ramsperger-Kassel (QRRK) analysis to calculate k(E) with master equation analysis to evaluate falloff in the chemically activated and dissociation reactions. One new, not previously reported, peroxy chemistry reaction is presented. It has a low barrier path and involves a concerted reaction resulting in olefin formation, H2O elimination, and an alkoxy radical.

The rapid-onset dystonia parkinsonism mutation D923N of the Na+, K+-ATPase alpha3 isoform disrupts Na+ interaction at the third Na+ site.

Science.gov (United States)

Einholm, Anja Pernille; Toustrup-Jensen, Mads S; Holm, Rikke; Andersen, Jens Peter; Vilsen, Bente

2010-08-20

Rapid-onset dystonia parkinsonism (RDP), a rare neurological disorder, is caused by mutation of the neuron-specific alpha3-isoform of Na(+), K(+)-ATPase. Here, we present the functional consequences of RDP mutation D923N. Relative to the wild type, the mutant exhibits a remarkable approximately 200-fold reduction of Na(+) affinity for activation of phosphorylation from ATP, reflecting a defective interaction of the E(1) form with intracellular Na(+). This is the largest effect on Na(+) affinity reported so far for any Na(+), K(+)-ATPase mutant. D923N also affects the interaction with extracellular Na(+) normally driving the E(1)P to E(2)P conformational transition backward. However, no impairment of K(+) binding was observed for D923N, leading to the conclusion that Asp(923) is specifically associated with the third Na(+) site that is selective toward Na(+). The crystal structure of the Na(+), K(+)-ATPase in E(2) form shows that Asp(923) is located in the cytoplasmic half of transmembrane helix M8 inside a putative transport channel, which is lined by residues from the transmembrane helices M5, M7, M8, and M10 and capped by the C terminus, recently found involved in recognition of the third Na(+) ion. Structural modeling of the E(1) form of Na(+), K(+)-ATPase based on the Ca(2+)-ATPase crystal structure is consistent with the hypothesis that Asp(923) contributes to a site binding the third Na(+) ion. These results in conjunction with our previous findings with other RDP mutants suggest that a selective defect in the handling of Na(+) may be a general feature of the RDP disorder.

E. s. r. of free radicals in irradiated uracil-. beta. -D-arabinofuranoside

Energy Technology Data Exchange (ETDEWEB)

Bergene, R [Oslo Univ. (Norway). Fysisk Institutt; Vaughan, R A

1976-02-01

Electron-spin-resonance measurements have been made on single crystals of uracil-..beta..-D-arabinofuranoside, which were irradiated by 4.0 MeV electrons at 77 K. At low temperatures, two radicals have been identified, one attributed to a hydrogen abstraction of 05' in the sugar moiety and the other to a radical anion located on the pyrimidine ring. The former was very unstable and seemed to act as a precursor to other unidentified radical species stable at 77 K. At room temperature, the main resonance was due to hydrogen addition to C5 and was probably produced by protonation of the anion. This same radical was also produced by irradiation at room temperature.

Integrated in situ characterization of molten salt catalyst surface: Evidence of sodium peroxide and OH radical formation

KAUST Repository

Takanabe, Kazuhiro; Khan, Abdulaziz M.; Tang, Yu; Nguyen, Luan; Ziani, Ahmed; Jacobs, Benjamin W; Elbaz, Ayman M.; Sarathy, S Mani; Tao, Franklin Feng

2017-01-01

Na-based catalysts (i.e., Na2WO4) were proposed to selectively catalyze OH radical formation from H2O and O2 at high temperatures. This reaction may proceed on molten salt state surfaces due to the lower melting point of the used Na salts compared to the reaction temperature. This study provides direct evidence of the molten salt state of Na2WO4, which can form OH radicals, using in situ techniques including X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), laser induced fluorescence (LIF) spectrometer, and ambient-pressure X-ray photoelectron spectroscopy (AP-XPS). As a result, Na2O2 species, which were hypothesized to be responsible for the formation of OH radicals, has been identified on the outer surfaces at temperatures ≥800°C, and these species are useful for various gas-phase hydrocarbon reactions including the selective transformation of methane to ethane.

Integrated in situ characterization of molten salt catalyst surface: Evidence of sodium peroxide and OH radical formation

KAUST Repository

Takanabe, Kazuhiro

2017-06-26

Na-based catalysts (i.e., Na2WO4) were proposed to selectively catalyze OH radical formation from H2O and O2 at high temperatures. This reaction may proceed on molten salt state surfaces due to the lower melting point of the used Na salts compared to the reaction temperature. This study provides direct evidence of the molten salt state of Na2WO4, which can form OH radicals, using in situ techniques including X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), laser induced fluorescence (LIF) spectrometer, and ambient-pressure X-ray photoelectron spectroscopy (AP-XPS). As a result, Na2O2 species, which were hypothesized to be responsible for the formation of OH radicals, has been identified on the outer surfaces at temperatures ≥800°C, and these species are useful for various gas-phase hydrocarbon reactions including the selective transformation of methane to ethane.

3D vision improves outcomes in early cervical cancer treated with laparoscopic type B radical hysterectomy and pelvic lymphadenectomy.

Science.gov (United States)

Raspagliesi, Francesco; Bogani, Giorgio; Martinelli, Fabio; Signorelli, Mauro; Scaffa, Cono; Sabatucci, Ilaria; Lorusso, Domenica; Ditto, Antonino

2017-01-21

To evaluate the alterations on surgical outcomes after of the implementation of 3D laparoscopic technology for the surgical treatment of early-stage cervical carcinoma. Data of patients undergoing type B radical hysterectomy (with or without bilateral salpingo-oophorectomy) and pelvic lymphadenectomy via 3D laparoscopy were compared with a historical cohort of patients undergoing type B radical hysterectomy via conventional laparoscopy. Complications (within 60 days) were graded per the Accordion severity system. Data of 75 patients were studied: 15 (20%) and 60 (80%) patients undergoing surgery via 3D laparoscopy and conventional laparoscopy, respectively. Baseline patient characteristics as well as pathologic findings were similar between groups (p>0.1). Patients undergoing 3D laparoscopy experienced a trend toward shorter operative time than patients undergoing conventional laparoscopy (176.7 ± 74.6 vs 215.9 ± 61.6 minutes; p = 0.09). Similarly, patients undergoing 3D laparoscopic radical hysterectomy experienced shorter length of hospital stay (2 days, range 2-6, vs 4 days, range 3-11; p<0.001) in comparison to patients in the control group, while no difference in estimated blood loss was observed (p = 0.88). No between-group difference in complication rate was observed. 3D technology is a safe and effective way to perform type B radical hysterectomy and pelvic node dissection in early-stage cervical cancer. Further large prospective studies are warranted in order to assess the cost-effectiveness of the introduction of 3D technology in comparison to robotic assisted surgery.

Heterogeneous Uptake of HO2 Radicals onto Atmospheric Aerosols

Science.gov (United States)

George, I. J.; Matthews, P. S.; Brooks, B.; Goddard, A.; Whalley, L. K.; Baeza-Romero, M. T.; Heard, D. E.

2011-12-01

The hydroxyl (OH) and hydroperoxyl (HO2) radicals, together known as HOx, play a vital role in atmospheric chemistry by controlling the oxidative capacity of the troposphere. The atmospheric lifetime and concentrations of many trace reactive species, such as volatile organic compounds (VOCs), are determined by HOx radical levels. Therefore, the ability to accurately predict atmospheric HOx concentrations from a detailed knowledge of their sources and sinks is a very useful diagnostic tool to assess our current understanding of atmospheric chemistry. Several recent field studies have observed significantly lower concentrations of HO2 radicals than predicted using box models, where HO2 loss onto aerosols was suggested as a possible missing sink [1, 2]. However, the mechanism on HO2 uptake onto aerosols and its impact on ambient HOx levels are currently not well understood. To improve our understanding of this process, we have conducted laboratory experiments to measure HO2 uptake coefficients onto submicron aerosol particles. The FAGE (Fluorescence Assay by Gas Expansion) technique, a highly sensitive laser induced fluorescence based detection method, was used to monitor HO2 uptake kinetics onto aerosol particles in an aerosol flow tube. The application of the FAGE technique allowed for kinetic experiments to be performed under low HO2 concentrations, i.e. [HO2] atomizing dilute salt solutions or by homogeneous nucleation. HO2 uptake coefficients (γ) have been measured for single-component solid and aqueous inorganic salt and organic aerosol particles with a wide range of hygroscopicities. HO2 uptake coefficients on solid particles were below the detection limit (γ < 0.001), whereas on aqueous aerosols uptake coefficients were somewhat larger (γ = 0.001 - 0.008). HO2 uptake coefficients were highest on aerosols containing metal ions, such as Cu and Fe. Humidity and aerosol pH did not significantly impact the reactive HO2 uptake. Preliminary experiments have also

Sobre a observação enquanto procedimento metodológico na análise do comportamento: positivismo lógico, operacionismo e behaviorismo radical

Directory of Open Access Journals (Sweden)

Alexandre Dittrich

Full Text Available A Análise do Comportamento adota duas posições distintas sobre a observação enquanto procedimento metodológico. Na análise experimental, tende-se a aceitar apenas a descrição de relações funcionais entre variáveis observáveis. Na análise interpretativa, contudo, relações funcionais entre variáveis observáveis e não-observáveis são inferidas. A posição da filosofia behaviorista radical sobre a questão torna-se mais clara quando examinada a partir da influência do operacionismo sobre a Psicologia, em especial nas décadas de 30 e 40. O presente artigo propõe-se a realizar tal exame, apoiando-se na literatura dedicada ao assunto e nos escritos de Skinner. Concluiu-se que a análise de eventos privados, proposta por Skinner: (1 é de natureza interpretativa; (2 refere-se, pelo menos em parte, a eventos inobserváveis publicamente; (3 lança mão, em alguma medida, da introspecção enquanto método; (4 lança mão, em alguma medida, de inferências sobre o mundo privado do outro.

O conceito de mal radical The concept of radical evil

Directory of Open Access Journals (Sweden)

Adriano Correia

2005-01-01

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

Striatal D2/3 Binding Potential Values in Drug-Naïve First-Episode Schizophrenia Patients Correlate With Treatment Outcome

Science.gov (United States)

Wulff, Sanne; Pinborg, Lars Hageman; Svarer, Claus; Jensen, Lars Thorbjørn; Nielsen, Mette Ødegaard; Allerup, Peter; Bak, Nikolaj; Rasmussen, Hans; Frandsen, Erik; Rostrup, Egill; Glenthøj, Birte Yding

2015-01-01

One of best validated findings in schizophrenia research is the association between blockade of dopamine D2 receptors and the effects of antipsychotics on positive psychotic symptoms. The aim of the present study was to examine correlations between baseline striatal D2/3 receptor binding potential (BPp) values and treatment outcome in a cohort of antipsychotic-naïve first-episode schizophrenia patients. Additionally, we wished to investigate associations between striatal dopamine D2/3 receptor blockade and alterations of negative symptoms as well as functioning and subjective well-being. Twenty-eight antipsychotic-naïve schizophrenia patients and 26 controls were included in the study. Single-photon emission computed tomography (SPECT) with [123I]iodobenzamide ([123I]-IBZM) was used to examine striatal D2/3 receptor BPp. Patients were examined before and after 6 weeks of treatment with the D2/3 receptor antagonist amisulpride. There was a significant negative correlation between striatal D2/3 receptor BPp at baseline and improvement of positive symptoms in the total group of patients. Comparing patients responding to treatment to nonresponders further showed significantly lower baseline BPp in the responders. At follow-up, the patients demonstrated a negative correlation between the blockade and functioning, whereas no associations between blockade and negative symptoms or subjective well-being were observed. The results show an association between striatal BPp of dopamine D2/3 receptors in antipsychotic-naïve first-episode patients with schizophrenia and treatment response. Patients with a low BPp have a better treatment response than patients with a high BPp. The results further suggest that functioning may decline at high levels of dopamine receptor blockade. PMID:25698711

A novel NhaD-type Na+/H+ antiporter from the moderate halophile and alkaliphile Halomonas alkaliphila.

Science.gov (United States)

Wang, Yanhong; Song, Na; Yang, Lina; Abdel-Motaal, Heba; Zhang, Rui; Zhang, Zhenglai; Meng, Fankui; Jiang, Juquan

2017-07-01

In this study, a NhaD-type Na + /H + antiporter gene designated Ha-nhaD was obtained by selection of genomic DNA from the moderate halophile and alkaliphile Halomonas alkaliphila in Escherichia coli KNabc lacking 3 major Na + /H + antiporters. The presence of Ha-NhaD conferred tolerance of E. coli KNabc to NaCl up to 0.6 mol·L -1 and to LiCl up to 0.2 mol·L -1 and to an alkaline pH. pH-dependent Na + (Li + )/H + antiport activity was detected from everted membrane vesicles prepared from E. coli KNabc/pUC-nhaD but not those of KNabc/pUC18. Ha-NhaD exhibited Na + (Li + )/H + antiport activity over a wide pH range from 7.0 to 9.5, with the highest activity at pH 9.0. Protein sequence alignment and phylogenetic analysis revealed that Ha-NhaD is significantly different from the 7 known NhaD-type Na + /H + antiporters, including Dw-NhaD, Dl-NhaD, Vp-NhaD, Vc-NhaD, Aa-NhaD, He-NhaD, and Ha-NhaD1. Although Ha-NhaD showed a closer phylogenetic relationship with Ha-NhaD2, a significant difference in pH-dependent activity profile exists between Ha-NhaD and Ha-NhaD2. Taken together, Ha-nhaD encodes a novel pH-dependent NhaD-type Na + /H + antiporter.

Studies of alpha-helicity and intersegmental interactions in voltage-gated Na+ channels: S2D4.

Directory of Open Access Journals (Sweden)

Zhongming Ma

2009-11-01

Full Text Available Much data, including crystallographic, support structural models of sodium and potassium channels consisting of S1-S4 transmembrane segments (the "voltage-sensing domain" clustered around a central pore-forming region (S5-S6 segments and the intervening loop. Voltage gated sodium channels have four non-identical domains which differentiates them from the homotetrameric potassium channels that form the basis for current structural models. Since potassium and sodium channels also exhibit many different functional characteristics and the fourth domain (D4 of sodium channels differs in function from other domains (D1-D3, we have explored its structure in order to determine whether segments in D4 of sodium channels differ significantly from that determined for potassium channels. We have probed the secondary and tertiary structure and the role of the individual amino acid residues of the S2D4 of Na(v1.4 by employing cysteine-scanning mutagenesis (with tryptophan and glutamine substituted for native cysteine. A Fourier transform power spectrum of perturbations in free energy of steady-state inactivation gating (using midpoint potentials and slopes of Boltzmann equation fits of channel availability, h(infinity-V plots indicates a substantial amount of alpha-helical structure in S2D4 (peak at 106 degrees, alpha-Periodicity Index (alpha-PI of 3.10, This conclusion is supported by alpha-PI values of 3.28 and 2.84 for the perturbations in rate constants of entry into (beta and exit from (alpha fast inactivation at 0 mV for mutant channels relative to WT channels assuming a simple two-state model for transition from the open to inactivated state. The results of cysteine substitution at the two most sensitive sites of the S2D4 alpha-helix (N1382 and E1392C support the existence of electrostatic network interactions between S2 and other transmembrane segments within Na(v1.4D4 similar to but not identical to those proposed for K+ channels.

Pseudo-ternary phase diagram in the Na2O-Na2O2-NaOH system

International Nuclear Information System (INIS)

Saito, Jun-ichi; Tendo, Masayuki; Aoto, Kazumi

1997-10-01

Generally, the phase diagrams are always used to understand the present state of compounds at certain temperature. In order to understand the corrosion behavior of structural material for FBR by main sodium compounds (Na 2 O, Na 2 O 2 and NaOH), it is very important to comprehend the phase diagrams of their compounds. However, only Na 2 O-NaOH pseudo-binary phase diagram had been investigated previously in this system. There is no study of other pseudo-binary or ternary phase diagrams in the Na 2 O-Na 2 O 2 -NaOH system. In this study, in order to clarify the present states of their compounds at certain temperatures, the pseudo-binary and ternary phase diagrams in the Na 2 O-Na 2 O 2 -NaOH system were prepared. A series of thermal analyses with binary and ternary component system has been carried out using the differential scanning calorimetry (DSC). The liquidus temperature and ternary eutectic temperatures were confirmed by these measurements. The beneficial indications for constructing phase diagrams were obtained from these experiments. On the basis of these results, the interaction parameters between compounds which were utilized for the Thermo-Calc calculation were optimized. Thermo-Calc is one of thermodynamic calculation software. Consequently the accurate pseudo-binary and ternary phase diagrams were indicated using the optimized parameters. (author)

Emission analysis of Tb3+ -and Sm3+ -ion-doped (Li2 O/Na2 O/K2 O) and (Li2 O + Na2 O/Li2 O + K2 O/K2 O + Na2 O)-modified borosilicate glasses.

Science.gov (United States)

Naveen Kumar Reddy, B; Sailaja, S; Thyagarajan, K; Jho, Young Dahl; Sudhakar Reddy, B

2018-05-01

Four series of borosilicate glasses modified by alkali oxides and doped with Tb 3+ and Sm 3+ ions were prepared using the conventional melt quenching technique, with the chemical composition 74.5B 2 O 3 + 10SiO 2 + 5MgO + R + 0.5(Tb 2 O 3 /Sm 2 O 3 ) [where R = 10(Li 2 O /Na 2 O/K 2 O) for series A and C, and R = 5(Li 2 O + Na 2 O/Li 2 O + K 2 O/K 2 O + Na 2 O) for series B and D]. The X-ray diffraction (XRD) patterns of all the prepared glasses indicate their amorphous nature. The spectroscopic properties of the prepared glasses were studied by optical absorption analysis, photoluminescence excitation (PLE) and photoluminescence (PL) analysis. A green emission corresponding to the 5 D 4 → 7 F 5 (543 nm) transition of the Tb 3+ ions was registered under excitation at 379 nm for series A and B glasses. The emission spectra of the Sm 3+ ions with the series C and D glasses showed strong reddish-orange emission at 600 nm ( 4 G 5/2 → 6 H 7/2 ) with an excitation wavelength λ exci = 404 nm ( 6 H 5/2 → 4 F 7/2 ). Furthermore, the change in the luminescence intensity with the addition of an alkali oxide and combinations of these alkali oxides to borosilicate glasses doped with Tb 3+ and Sm 3+ ions was studied to optimize the potential alkali-oxide-modified borosilicate glass. Copyright © 2017 John Wiley & Sons, Ltd.

Interactions between simple radicals and water

International Nuclear Information System (INIS)

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

2008-01-01

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

Scavenging performance and antioxidant activity of γ-alumina nanoparticles towards DPPH free radical: Spectroscopic and DFT-D studies.

Science.gov (United States)

Zamani, Mehdi; Moradi Delfani, Ali; Jabbari, Morteza

2018-05-03

The radical scavenging performance and antioxidant activity of γ-alumina nanoparticles towards 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical were investigated by spectroscopic and computational methods. The radical scavenging ability of γ-alumina nanoparticles in the media with different polarity (i.e. i-propanol and n-hexane) was evaluated by measuring the DPPH absorbance in UV-Vis absorption spectra. The structure and morphology of γ-alumina nanoparticles before and after adsorption of DPPH were studied using XRD, FT-IR and UV-Vis spectroscopic techniques. The adsorption of DPPH free radical on the clean and hydrated γ-alumina (1 1 0) surface was examined by dispersion corrected density functional theory (DFT-D) and natural bond orbital (NBO) calculations. Also, time-dependent density functional theory (TD-DFT) was used to predict the absorption spectra. The adsorption was occurred through the interaction of radical nitrogen N and NO 2 groups of DPPH with the acidic and basic sites of γ-alumina surface. The high potential for the adsorption of DPPH radical on γ-alumina nanoparticles was investigated. Interaction of DPPH with Brønsted and Lewis acidic sites of γ-alumina was more favored than Brønsted basic sites. The following order for the adsorption of DPPH over the different active sites of γ-alumina was predicted: Brønsted base free radicals. Copyright © 2018. Published by Elsevier B.V.

Ab initio study of the Si(CH3)2O double free radical under external electric field

International Nuclear Information System (INIS)

Chen Xiaojun; Luo Sunzhong; Jiang Shubing; Huang Wei; Gao Xiaoling; Ma Meizhong; Zhu Zhenghe

2004-01-01

Infrared spectrum and NMR chemical shifts of Si(CH 3 ) 2 O double free radical were calculated employing density functional theory (DFT) with the basis sets 6-311 + G(2d, p). Excited states, dipole moment and energy of Si(CH 3 ) 2 O double free radical were also calculated using time dependent density function theory (TD-DFT) with the same basis sets. It is found that the external electric field along the X, Y and Z axis affect differently on the excited states and other properties of Si(CH 3 ) 2 O double free radical. (author)

Evidence of radicals created by plasma in bacteria in water

International Nuclear Information System (INIS)

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

2014-01-01

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

Shape-Control of a 0D/1D NaFe0.9Mn0.1PO4 Nano-Complex by Electrospinning

Science.gov (United States)

Shin, Mi-Ra; Son, Jong-Tae

2018-03-01

NaFePO4 with a maricite structure was one of the most promising candidates for sodium ion batteries (SIBs) due to its advantages of environmental friendly and having low cost. However, it has low electrochemical conductivity and energy density, which impose limitations on its application as commercial cathode materials. In this study, other transition-metal ions such as Mn2+ were substituted into the iron (Fe2+) site in NaFePO4 to increase the surface area and the number of nanofibers in the prepared one-dimensional (1D) nano-sized material with 0D/1D dimensions to enhance the energy density. Also, the 0D/1D NaFe0.9Mn0.1PO4 cathode material has increased electrochemical conductivity because the fiber size was reduced to the nano-scale level by using the electrospinning method in order to decrease the diffusion path of Na-ions. The morphology of the 0D/1D nanofiber was evaluated by Field-emission scanning electron microscope and atomic force microscope analyses. The NaFe0.9Mn0.1PO4 nanofibers had a diameter of approximately 180 nm, while the spherical particle had a diameter 1 μm. The 0D/1D nano-sized cathode material show a discharge capacity of 27 mAhg -1 at a 0.05 C rate within the 2.0 4.5 V voltage range and a low R ct of 110 Ω.

The structure of Na sub 3 H sub 2 As sub 3 O sub 10. Structure d'un triarseniate: Na sub 3 H sub 2 As sub 3 O sub 10

Energy Technology Data Exchange (ETDEWEB)

Driss, A.; Jouini, T. (Tunis Univ. (Tunisia). Dept. de Chimie)

1990-07-15

Na{sub 3}H{sub 2}As{sub 3}O{sub 10}, M{sub r}=455.75, monoclinic, C2/c, a=10.860 (3), b=9.323 (3), c=18.270 (5) A, {beta}=103.00 (2)deg, V=1802 (1) A{sup 3}, Z=8, D{sub x}=3.27, D{sub m} (in bromobenzene) = 3.30 Mg m{sup -3}, {lambda}(Mo K anti {alpha})=0.7107 A, {mu}=11.5 mm{sup -1}, F(000)=1712, room temperature, final R=0.035 and wR=0.038 for 578 reflections. This structure contains a triarsenate anion H{sub 2}As{sub 3}O{sub 10}{sup 3-} formed from three AsO{sub 4} tetrahedra pointing in the same direction. They are connected by hydrogen bonds to form layers parallel to held (10anti 1) together by interleaved Na{sup +} cations. Only few triarsenate structures are known. The corresponding phosphate is unknown. An explanation is proposed. (orig.).

Apparent molar volumes for dilute solutions of NaClO4 and [Co(en) 3](ClO4)3 in D2O and H2O at 278-318 K

International Nuclear Information System (INIS)

Bottomley, G.A.; Glossop, L.G.

1981-01-01

Apparent molar volumes for dilute solutions of NaClO 4 and [Co(en) 3 ](ClO 4 ) 3 in D 2 O and H 2 O were measured by using a dilatometry technique at 278, 298 and 318K. Comparison of limiting slopes with the Debye-Huckel predictions from the dielectric constant and compressibility of H 2 O and D 2 O is complicated by ion pairing. The apparent molar volumes for NaClO 4 were less in D 2 O than in H 2 O. The complex [Co(en) 3 ](ClO 4 ) 3 when studied in D 2 O had its amine protons exchanged by deuterium; this did not allow a direct comparison of the apparent molar volumes of the protonated complex in each solvent system, but revealed a large isotope effect. The apparent molar volumes of the [Co(en) 3 ](ClO 4 ) 3 showed a much larger temperature dependence than that of NaClO 4

Age-dependent changes in diastolic Ca2+ and Na+ concentrations in dystrophic cardiomyopathy: Role of Ca2+ entry and IP3

International Nuclear Information System (INIS)

Mijares, Alfredo; Altamirano, Francisco; Kolster, Juan; Adams, José A.; López, José R.

2014-01-01

Highlights: • Age-dependent increase in [Ca 2+ ] d and [Na + ] d in mdx cardiomyocytes. • Gadolinium significantly reduced both [Ca 2+ ] d and [Na + ] d at all ages. • IP 3 -pathway inhibition reduced cations concentrations in dystrophic cardiomyocytes. - Abstract: Duchenne muscular dystrophy (DMD) is a lethal X-inherited disease caused by dystrophin deficiency. Besides the relatively well characterized skeletal muscle degenerative processes, DMD is also associated with a dilated cardiomyopathy that leads to progressive heart failure at the end of the second decade. The aim of the present study was to characterize the diastolic Ca 2+ concentration ([Ca 2+ ] d ) and diastolic Na + concentration ([Na + ] d ) abnormalities in cardiomyocytes isolated from 3-, 6-, 9-, and 12-month old mdx mice using ion-selective microelectrodes. In addition, the contributions of gadolinium (Gd 3+ )-sensitive Ca 2+ entry and inositol triphosphate (IP 3 ) signaling pathways in abnormal [Ca 2+ ] d and [Na + ] d were investigated. Our results showed an age-dependent increase in both [Ca 2+ ] d and [Na + ] d in dystrophic cardiomyocytes compared to those isolated from age-matched wt mice. Gd 3+ treatment significantly reduced both [Ca 2+ ] d and [Na + ] d at all ages. In addition, blockade of the IP 3 -pathway with either U-73122 or xestospongin C significantly reduced ion concentrations in dystrophic cardiomyocytes. Co-treatment with U-73122 and Gd 3+ normalized both [Ca 2+ ] d and [Na + ] d at all ages in dystrophic cardiomyocytes. These data showed that loss of dystrophin in mdx cardiomyocytes produced an age-dependent intracellular Ca 2+ and Na + overload mediated at least in part by enhanced Ca 2+ entry through Gd 3+ sensitive transient receptor potential channels (TRPC), and by IP 3 receptors

Product study of 1-adamantyl and 1-bicyclo[2.2.2]octyl radicals in hydrocarbon solvents. An unusually large hydrogen isotope effect

International Nuclear Information System (INIS)

Engel, P.S.; Chae, W.K.; Baughman, S.A.; Marschke, G.E.; Lewis, E.S.; Timberlake, J.W.; Luedtke, A.E.

1983-01-01

1-Adamantyl (ada.) and 1-bicyclo[2.2.2]octyl (bo.) radicals have been generated by photolysis of the corresponding azoalkanes in various hydrocarbon solvents. Both radicals abstract hydrogen readily from saturated hydrocarbons and they add to aromatic rings much faster than tert-butyl. does. Despite its reactivity, ada. is remarkably selective in hydrogen atom abstraction, preferring a benzylic hydrogen 25:1 over a cyclohexane hydrogen. The effect of solvent viscosity indicates that formation of the radical dimers biada and bibo occurs in the solvent cage. The most striking result of this work is a deuterium isotope effect of 25 for hydrogen transfer from cyclohexane to ada. at 65 0 C. Steric compression in the transition state is postulated to cause an unusually large tunnel correction and hence a large k/sub H//k/sub D/. 6 tables

Efecto secuestrador del D-002 sobre radicales hidroxilo en mucosa gástrica Scavenger effect of D-002 on hydroxyl radicals in the gastric mucosa

Directory of Open Access Journals (Sweden)

Yohani Pérez Guerra

2012-03-01

Full Text Available Introducción: el agente causal de la ulceración gástrica está asociado al desequilibrio entre factores agresivos y defensivos que actúan sobre la mucosa gástrica. El D-002, mezcla de seis alcoholes alifáticos primarios superiores purificada de la cera de abejas, produce efectos gastroprotectores mediados por múltiples mecanismos y reducción de la peroxidación lipídica en la mucosa gástrica. Objetivo: determinar si el D-002 es capaz de capturar el radical hidroxilo añadido in vitro o generado in vivo en ratas con úlcera gástrica inducida por indometacina. Métodos: En la experiencia in vitro el D-002 se añadió a concentraciones entre 0,9 y 1 000 mg/mL. En la experiencia in vivo las ratas se distribuyeron en seis grupos: un control negativo y cinco que recibieron indometacina: un control positivo tratado con el vehículo, tres con D-002 (5, 25, y 100 mg/kg, respectivamente, p.o. y otro con omeprazol (20 mg/kg i.p.. Los tratamientos se administraron una hora (vehículo y D-002 o 30 min (omeprazol, respectivamente, antes de inducir las úlceras. En ambas experiencias se tomaron alícuotas de mucosa gástrica, y se determinó el daño a la 2-desoxirribosa por el radical hidroxilo. Resultados: la administración oral del D-002, no in vitro, protegió a la 2-desoxirribosa del daño oxidativo de modo marcado, significativo y dependiente de la dosis con respecto al control positivo. Conclusiones: los resultados indican que la capacidad del D-002 (25 y 100 mg/kg administrado por vía oral para secuestrar el radical hidroxilo, generado en la mucosa gástrica por la indometacina, pudiera contribuir a sus efectos antioxidantes y gastroprotectores sobre el daño que los antiinflamatorios no esteroideos producen sobre la mucosa gástrica.Introduction: the etiology of the gastric ulceration is associated to the imbalance between aggressive and defensive factors acting upon the gastric mucosa. D-002, a mixture of 6 higher primary alcohols

Loading of free radicals on the functional graphene combined with liquid chromatography-tandem mass spectrometry screening method for the detection of radical-scavenging natural antioxidants.

Science.gov (United States)

Wang, Guoying; Shi, Gaofeng; Chen, Xuefu; Chen, Fuwen; Yao, Ruixing; Wang, Zhenju

2013-11-13

A novel free radical reaction combined with liquid chromatography electrospray ionization tandem mass spectrometry (FRR-LC-PDA-ESI/APCI-MS/MS) screening method was developed for the detection and identification of radical-scavenging natural antioxidants. Functionalized graphene was prepared by chemical method for loading free radicals (superoxide radical, peroxyl radical and PAHs free radical). Separation was performed with and without a preliminary exposure of the sample to specific free radicals on the functionalized graphene, which can facilitate reaction kinetics (charge transfers) between free radicals and potential antioxidants. The difference in chromatographic peak areas is used to identify potential antioxidants. The structure of the antioxidants in one sample (Swertia chirayita) is identified using MS/MS and comparison with standards. Thirteen compounds were found to possess potential antioxidant activity, and their free radical-scavenging capacities were investigated. The thirteen compounds were identified as 1,3,5-trihydroxyxanthone-8-O-β-D-glucopyranoside (PD1), norswertianin (PD2), 1,3,5,8-tetrahydroxyxanthone (PD3), 3, 3', 4', 5, 8-penta hydroxyflavone-6-β-D-glucopyranosiduronic acid-6'-pentopyranose-7-O-glucopyranoside (PD4), 1,5,8-trihydroxy-3-methoxyxanthone (PD5), swertiamarin (PS1), 2-C-β-D-glucopyranosyl-1,3,7-trihydroxylxanthone (PS2), 1,3,7-trihydroxylxanthone-8-O-β-D-glucopyranoside (PL1), 1,3,8-trihydroxyl xanthone-5-O-β-D-glucopyranoside (PL2), 1,3,7-trihydroxy-8-methoxyxanthone (PL3), 1,2,3-trihydroxy-7,8-dimethoxyxanthone (PL4), 1,8-dihydroxy-2,6-dimethoxy xanthone (PL5) and 1,3,5,8-tetramethoxydecussatin (PL6). The reactivity and SC50 values of those compounds were investigated, respectively. PD4 showed the strongest capability for scavenging PAHs free radical; PL4 showed prominent scavenging capacities in the lipid peroxidation processes; it was found that all components in S. chirayita exhibited weak reactivity in the superoxide

The Na+ transporter, TaHKT1;5-D, limits shoot Na+ accumulation in bread wheat

KAUST Repository

Byrt, Caitlin Siobhan

2014-10-01

Bread wheat (Triticum aestivum L.) has a major salt tolerance locus, Kna1, responsible for the maintenance of a high cytosolic K+/Na+ ratio in the leaves of salt stressed plants. The Kna1 locus encompasses a large DNA fragment, the distal 14% of chromosome 4DL. Limited recombination has been observed at this locus making it difficult to map genetically and identify the causal gene. Here, we decipher the function of TaHKT1;5-D, a candidate gene underlying the Kna1 locus. Transport studies using the heterologous expression systems Saccharomyces cerevisiae and Xenopus laevis oocytes indicated that TaHKT1;5-D is a Na+-selective transporter. Transient expression in Arabidopsis thaliana mesophyll protoplasts and in situ polymerase chain reaction indicated that TaHKT1;5-D is localised on the plasma membrane in the wheat root stele. RNA interference-induced silencing decreased the expression of TaHKT1;5-D in transgenic bread wheat lines which led to an increase in the Na+ concentration in the leaves. This indicates that TaHKT1;5-D retrieves Na+ from the xylem vessels in the root and has an important role in restricting the transport of Na+ from the root to the leaves in bread wheat. Thus, TaHKT1;5-D confers the essential salinity tolerance mechanism in bread wheat associated with the Kna1 locus via shoot Na+ exclusion and is critical in maintaining a high K+/Na+ ratio in the leaves. These findings show there is potential to increase the salinity tolerance of bread wheat by manipulation of HKT1;5 genes.

The Na+ transporter, TaHKT1;5-D, limits shoot Na+ accumulation in bread wheat

KAUST Repository

Byrt, Caitlin Siobhan; Xu, Bo; Krishnan, Mahima; Lightfoot, Damien; Athman, Asmini; Jacobs, Andrew Keith; Watson-Haigh, Nathan S.; Plett, Darren; Munns, Rana; Tester, Mark A.; Gilliham, Matthew

2014-01-01

Bread wheat (Triticum aestivum L.) has a major salt tolerance locus, Kna1, responsible for the maintenance of a high cytosolic K+/Na+ ratio in the leaves of salt stressed plants. The Kna1 locus encompasses a large DNA fragment, the distal 14% of chromosome 4DL. Limited recombination has been observed at this locus making it difficult to map genetically and identify the causal gene. Here, we decipher the function of TaHKT1;5-D, a candidate gene underlying the Kna1 locus. Transport studies using the heterologous expression systems Saccharomyces cerevisiae and Xenopus laevis oocytes indicated that TaHKT1;5-D is a Na+-selective transporter. Transient expression in Arabidopsis thaliana mesophyll protoplasts and in situ polymerase chain reaction indicated that TaHKT1;5-D is localised on the plasma membrane in the wheat root stele. RNA interference-induced silencing decreased the expression of TaHKT1;5-D in transgenic bread wheat lines which led to an increase in the Na+ concentration in the leaves. This indicates that TaHKT1;5-D retrieves Na+ from the xylem vessels in the root and has an important role in restricting the transport of Na+ from the root to the leaves in bread wheat. Thus, TaHKT1;5-D confers the essential salinity tolerance mechanism in bread wheat associated with the Kna1 locus via shoot Na+ exclusion and is critical in maintaining a high K+/Na+ ratio in the leaves. These findings show there is potential to increase the salinity tolerance of bread wheat by manipulation of HKT1;5 genes.

Na-Ion Intercalation and Charge Storage Mechanism in 2D Vanadium Carbide

Energy Technology Data Exchange (ETDEWEB)

Bak, Seong-Min [Chemistry Division, Brookhaven National Laboratory, Upton NY 11973 USA; Qiao, Ruimin [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley CA 94720 USA; Yang, Wanli [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley CA 94720 USA; Lee, Sungsik [X-Ray Science Division, Argonne National Laboratory, Argonne IL 60439 USA; Yu, Xiqian [Institute of Physics, Chinese Academy of Science, Beijing 100190 China; Anasori, Babak [Department of Material Science and Engineering, A.J. Drexel Nanomaterials Institute, Drexel University, Philadelphia PA 19104 USA; Lee, Hungsui [Chemistry Division, Brookhaven National Laboratory, Upton NY 11973 USA; Gogotsi, Yury [Department of Material Science and Engineering, A.J. Drexel Nanomaterials Institute, Drexel University, Philadelphia PA 19104 USA; Yang, Xiao-Qing [Chemistry Division, Brookhaven National Laboratory, Upton NY 11973 USA

2017-07-14

Two-dimensional vanadium carbide MXene containing surface functional groups (denoted as V2CTx, where Tx are surface functional groups) was synthesized and studied as anode material for Na-ion batteries. V2CTx anode exhibits reversible charge storage with good cycling stability and high rate capability through electrochemical test. The charge storage mechanism of V2CTx material during Na+ intercalation/deintercalation and the redox reaction of vanadium were studied using a combination of synchrotron based X-ray diffraction (XRD), hard X-ray absorption near edge spectroscopy (XANES) and soft X-ray absorption spectroscopy (sXAS). Experimental evidence of a major contribution of redox reaction of vanadium to the charge storage and the reversible capacity of V2CTx during sodiation/desodiation process have been provided through V K-edge XANES and V L2,3-edge sXAS results. A correlation between the CO32- content and Na+ intercalation/deintercalation states in the V2CTx electrode observed from C and O K-edge in sXAS results imply that some additional charge storage reactions may take place between the Na+-intercalated V2CTx and the carbonate based non-aqueous electrolyte. The results of this study will provide valuable information for the further studies on V2CTx as anode material for Na-ion batteries and capacitors.

Ion pairing of radical ions of aromatic alkenes and alkynes studied by pulse radiolysis

International Nuclear Information System (INIS)

Yamamoto, Satoshi; Yamamoto, Yukio; Hayashi, Koichiro

1991-01-01

Pulse radiolysis of 1,2-dichloroethane solutions of trans,trans-1,4-bis(2-phenylethenyl)benzene and 1,4-bis(2-phenylethynyl)benzene was undertaken in the presence of Bu 4 NPF 6 (Bu=butyl) to investigate the effect of ion pairing of the solute radical cations with PF 6 - . It was also undertaken for the tetrahydrofuran solutions of the above compounds in the presence of Bu 4 NPF 6 and NaBPh 4 , where the solute radical anions are generated and form ion pairs with Bu 4 N + and Na + . The decay of the radical ions, which is due to neutralization, is retarded by the ion pairing. The rate constants for the neutralization reactions in the free-ion and ion-paired states were determined. Also presented are the data for the radical ions of trans-stilbene, diphenylacetylene, trans,trans-1,4-diphenyl-1,3-butadiene, and diphenylbutadiene. The radical ions of the aromatic alkynes are less stabilized by the ion pairing than those of the aromatic alkenes having the same carbon skeletons probably because of more extensive charge delocalization of the former radical ions. Spectral shifts to shorter wavelengths caused by the ion pairing are appreciable for the radical anions. Dependence of the spectral shifts on the size of the radical anions is described. (author)

Electron color centers in SrF2-Na crystals

International Nuclear Information System (INIS)

Kachan, S.I.; Chornij, Z.P.

2006-01-01

A radiation-induced memory effect in SrF 2 -Na crystals is studied. It was shown that optical bleaching of M + A color centers at 80 K in SrF 2 -Na crystals causes the core of an M + A -center to transform into the V + a Me + V + a configuration, in which all three point defects are arranged diagonally in the cube cell. Reirradiation of an optically bleached crystal by X-rays generates F D centers in it. The F D →M + A transformation in SrF 2 -Na crystals occurs at T = 135 K, in contrast to the F A →M + A transformations, which take place at T > 200 K [ru

Radiation damage to human erythrocytes. Relative contribution of hydroxyl and chloride radicals in N2O-saturated buffers

International Nuclear Information System (INIS)

Krokosz, Anita; Komorowska, Magdalena A.; Szweda-Lewandowska, Zofia

2008-01-01

The erythrocyte suspensions in Na-phosphate buffered isotonic NaCl solution (PBS) or Na-phosphate isotonic buffer (PB) (hematocrit 1%) were irradiated with the dose of 400 Gy under N 2 O. Erythrocytes were incubated in the medium in which the cells were irradiated or in fresh PBS. The level of damage to cells was estimated on the basis of the course of post-radiation hemolysis and hemoglobin (Hb) oxidation. The medium in which the cells were irradiated and incubated influenced the course of the post-radiation hemolysis and Hb oxidation as well as some other parameters. We discussed the contribution of hydroxyl and chloride radicals in the initiation of erythrocyte damage and oxygen modification of these processes

Assessment of Free Radical Scavenging Activity of Dimethylglycine Sodium Salt and Its Role in Providing Protection against Lipopolysaccharide-Induced Oxidative Stress in Mice.

Science.gov (United States)

Bai, Kaiwen; Xu, Wen; Zhang, Jingfei; Kou, Tao; Niu, Yu; Wan, Xiaoli; Zhang, Lili; Wang, Chao; Wang, Tian

2016-01-01

In the present study, the free radical scavenging activities (against 1,1-diphenyl-2-pierylhydrazy (DPPH), 2,2'-Azinobis-(3-ethylbenzthiazoline-6- sulphonate) (ABTS+), Hydrogen peroxide (H2O2)) of dimethylglycine sodium salt (DMG-Na) were measured and compared with those of Trolox (6-hydroxy-2, 5, 7, 8-tetramethylchroman-2-carboxylic acid), a commonly used antioxidant. The radical scavenging activities of DMG-Na were found to be the highest at 40 mg/ml. In Experiment 2, gastric intubation in mice with 12 mg DMG-Na/0.3 ml sterile saline solution significantly increased (P DMG-Na/0.3 ml sterile saline solution, which showed the highest antioxidant capacity, was further studied using a mice model. In Experiment 3, the mice CL (CON+ lipopolysaccharide (LPS)) group showed a significant decrease (P DMG+LPS) group showed a significant decrease (P DMG-Na could protect against the LPS-induced oxidative stress by enhancing the free radical scavenging capacity, and increasing the activity of antioxidant defense system.

PROTO-PLANETARY DISK CHEMISTRY RECORDED BY D-RICH ORGANIC RADICALS IN CARBONACEOUS CHONDRITES

International Nuclear Information System (INIS)

Remusat, Laurent; Robert, Francois; Meibom, Anders; Mostefaoui, Smail; Delpoux, Olivier; Binet, Laurent; Gourier, Didier; Derenne, Sylvie

2009-01-01

Insoluble organic matter (IOM) in primitive carbonaceous meteorites has preserved its chemical composition and isotopic heterogeneity since the solar system formed ∼4.567 billion years ago. We have identified the carrier moieties of isotopically anomalous hydrogen in IOM isolated from the Orgueil carbonaceous chondrite. Data from high spatial resolution, quantitative isotopic NanoSIMS mapping of Orgueil IOM combined with data from electron paramagnetic resonance spectroscopy reveals that organic radicals hold all the deuterium excess (relative to the bulk IOM) in distinct, micrometer-sized, D-rich hotspots. Taken together with previous work, the results indicate that an isotopic exchange reaction took place between pre-existing organic compounds characterized by low D/H ratios and D-rich gaseous molecules, such as H 2 D + or HD 2 + . This exchange reaction most likely took place in the diffuse outer regions of the proto-planetary disk around the young Sun, offering a model that reconciles meteoritic and cometary isotopic compositions of organic molecules.

Proto-Planetary Disk Chemistry Recorded by D-Rich Organic Radicals in Carbonaceous Chondrites

Science.gov (United States)

Remusat, Laurent; Robert, François; Meibom, Anders; Mostefaoui, Smail; Delpoux, Olivier; Binet, Laurent; Gourier, Didier; Derenne, Sylvie

2009-06-01

Insoluble organic matter (IOM) in primitive carbonaceous meteorites has preserved its chemical composition and isotopic heterogeneity since the solar system formed ~4.567 billion years ago. We have identified the carrier moieties of isotopically anomalous hydrogen in IOM isolated from the Orgueil carbonaceous chondrite. Data from high spatial resolution, quantitative isotopic NanoSIMS mapping of Orgueil IOM combined with data from electron paramagnetic resonance spectroscopy reveals that organic radicals hold all the deuterium excess (relative to the bulk IOM) in distinct, micrometer-sized, D-rich hotspots. Taken together with previous work, the results indicate that an isotopic exchange reaction took place between pre-existing organic compounds characterized by low D/H ratios and D-rich gaseous molecules, such as H2D+ or HD2 +. This exchange reaction most likely took place in the diffuse outer regions of the proto-planetary disk around the young Sun, offering a model that reconciles meteoritic and cometary isotopic compositions of organic molecules.

Favoring D2-Lymphadenectomy in Gastric Cancer.

Science.gov (United States)

Karavokyros, Ioannis; Michalinos, Adamantios

2018-01-01

The role of extended lymphadenectomy in the surgical treatment of gastric cancer has been debated for many years. So far six prospective randomized trials and a number of meta-analyses comparing D 1 - to D 2 -lymphadenectomy in open surgery have been published with contradicting results. The possible oncologic benefit of radical lymphadenectomy has been blurred by a number of reasons. In most of the trials the strategies under comparison were made similar after protocol violations. Imperfect design of the trials could not exclude the influence of cofounding factors. Inappropriate endpoints could not detect evidently the difference between the two surgical strategies. On the other hand radical lymphadenectomy was characterized by increased morbidity and mortality. This was mostly caused by the addition of pancreatico-splenectomy in all D 2 -dissections, even when not indicated. A careful analysis of the available evidence indicates that D 2 -lymphadenectomy performed by adequately trained surgeons without resection of the pancreas and/or spleen, unless otherwise indicated, decreases Gastric Cancer Related Deaths and increases Disease Specific Survival. This evidence is not compelling but cannot be ignored. D 2 -lymphadendctomy is nowadays considered to be the standard of care for resectable gastric cancer.

Striatal D_2/3 Binding Potential Values in Drug-Naïve First-Episode Schizophrenia Patients Correlate With Treatment Outcome

DEFF Research Database (Denmark)

Wulff, Sanne; Pinborg, Lars Hageman; Svarer, Claus

2015-01-01

potential (BP(p)) values and treatment outcome in a cohort of antipsychotic-naïve first-episode schizophrenia patients. Additionally, we wished to investigate associations between striatal dopamine D(2/3) receptor blockade and alterations of negative symptoms as well as functioning and subjective well......-being. Twenty-eight antipsychotic-naïve schizophrenia patients and 26 controls were included in the study. Single-photon emission computed tomography (SPECT) with [(123)I]iodobenzamide ([(123)I]-IBZM) was used to examine striatal D(2/3) receptor BP(p). Patients were examined before and after 6 weeks...... of treatment with the D(2/3) receptor antagonist amisulpride. There was a significant negative correlation between striatal D(2/3) receptor BP(p) at baseline and improvement of positive symptoms in the total group of patients. Comparing patients responding to treatment to nonresponders further showed...

Electronic structure of 2,5,8-tri-tert-butylphenalenyl radical studied by He(I) photoelectron spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Kubota, Mari [School of Medicine, Keio University, Hiyoshi-4, Kohoku, Yokohama 223-8521 (Japan)], E-mail: marik@hc.cc.keio.ac.jp; Kobayashi, Tsunetoshi [School of Medicine, Keio University, Hiyoshi-4, Kohoku, Yokohama 223-8521 (Japan); Kubo, Takashi; Nakasuji, Kazuhiro [Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan)

2008-09-15

Phenalenyl radical is an odd-alternant hydrocarbon radical of high symmetry, D{sub 3h} and is extremely attractive as the constituent of molecular magnets. But it has not been characterized in detail. Recently, 2,5,8-tri-tert-butylphenalenyl radical has successfully been synthesized. In this work the gas phase He(I) photoelectron spectrum of this radical has been measured and analyzed with the aid of UHF MO and RHF MO SECI calculations. The first band has been assigned to the ionization from the SO-{pi}-MO of the neutral radical. The second band group has been ascribed to the ionized states relevant to three triplet ionic states and one singlet ionic state of the monocation, the third band group being ascribed to the two singlet ionic states of the monocation.

Application of PhSCF2CF2SiMe3 as a Tandem Anion and Radical Tetrafluoroethylene Equivalent: Fluoride-Catalyzed Addition to N-Substituted Cyclic Imides Followed by Radical Cyclization

Czech Academy of Sciences Publication Activity Database

Chernykh, Yana; Opekar, Stanislav; Klepetářová, Blanka; Beier, Petr

2012-01-01

Roč. 23, č. 8 (2012), s. 1187-1190 ISSN 0936-5214 R&D Projects: GA ČR GAP207/11/0421 Institutional research plan: CEZ:AV0Z40550506 Keywords : nucleophilic addition * radical reaction * fluorine * heterocycles * imides Subject RIV: CC - Organic Chemistry Impact factor: 2.655, year: 2012

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

Science.gov (United States)

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

1991-03-01

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

1,2-Fluorine Radical Rearrangements: Isomerization Events in Perfluorinated Radicals.

Science.gov (United States)

Van Hoomissen, Daniel J; Vyas, Shubham

2017-11-16

Devising effective degradation technologies for perfluoroalkyl substances (PFASs) is an active area of research, where the molecular mechanisms involving both oxidative and reductive pathways are still elusive. One commonly neglected pathway in PFAS degradation is fluorine atom migration in perfluoroalkyl radicals, which was largely assumed to be implausible because of the high C-F bond strength. Using density functional theory calculations, it was demonstrated that 1,2-F atom migrations are thermodynamically favored when the fluorine atom migrated from a less branched carbon center to a more branched carbon center. Activation barriers for these rearrangements were within 19-29 kcal/mol, which are possible to easily overcome at elevated temperatures or in photochemically activated species in the gas or aqueous phase. It was also found that the activation barriers for the 1,2-F atom migration are lowered as much as by 10 kcal/mol when common oxidative degradation products such as HF assisted the rearrangements or if the resulting radical center was stabilized by vicinal π-bonds. Natural bond orbital analyses showed that fluorine moves as a radical in a noncharge-separated state. These findings add an important reaction to the existing knowledge of mechanisms for PFAS degradation and highlights the fact that 1,2-F atom shifts may be a small channel for isomerization of these compounds, but upon availability of mineralization products, this isomerization process could become more prominent.

Measuring Atmospheric Free Radicals Using Chemical Amplification

Science.gov (United States)

1988-05-01

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

2D/2D nano-hybrids of γ-MnO{sub 2} on reduced graphene oxide for catalytic ozonation and coupling peroxymonosulfate activation

Energy Technology Data Exchange (ETDEWEB)

Wang, Yuxian [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing Engineering Research Center of Process Pollution Control, Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Department of Chemical Engineering, Curtin University, GPO Box U1987, Perth, WA 6845 (Australia); Xie, Yongbing, E-mail: ybxie@ipe.ac.cn [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing Engineering Research Center of Process Pollution Control, Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Sun, Hongqi [Department of Chemical Engineering, Curtin University, GPO Box U1987, Perth, WA 6845 (Australia); Xiao, Jiadong; Cao, Hongbin [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing Engineering Research Center of Process Pollution Control, Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Wang, Shaobin, E-mail: shaobin.wang@curtin.edu.au [Department of Chemical Engineering, Curtin University, GPO Box U1987, Perth, WA 6845 (Australia)

2016-01-15

Highlights: • 2D γ-MnO{sub 2}/2D rGO hybrids (MnO{sub 2}/rGO) via a facile hydrothermal route were prepared. • MnO{sub 2}/rGO exhibits high activity in catalytic ozonation of 4-nitrophenol. • ·O{sub 2}{sup ̄} and {sup 1}O{sub 2} are the major radicals for 4-nitrophenol degradation and mineralization. • A synergistic effect of ozonation and peroxymonosulfate oxidation was evaluated. - Abstract: Two-dimensional reduced graphene oxide (2D rGO) was employed as both a shape-directing medium and support to fabricate 2D γ-MnO{sub 2}/2D rGO nano-hybrids (MnO{sub 2}/rGO) via a facile hydrothermal route. For the first time, the 2D/2D hybrid materials were used for catalytic ozonation of 4-nitrophenol. The catalytic efficiency of MnO{sub 2}/rGO was much higher than either MnO{sub 2} or rGO only, and rGO was suggested to play the role for promoting electron transfers. Quenching tests using tert-butanol, p-benzoquinone, and sodium azide suggested that the major radicals responsible for 4-nitrophenol degradation and mineralization are O{sub 2}{sup ̄} and {sup 1}O{sub 2}, but not ·OH. Reusability tests demonstrated a high stability of the materials in catalytic ozonation with minor Mn leaching below 0.5 ppm. Degradation mechanism, reaction kinetics, reusability and a synergistic effect between catalytic ozonation and coupling peroxymonosulfate (PMS) activation were also discussed.

Superoxide radical (O2-) reactivity with respect to glutathione

International Nuclear Information System (INIS)

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

1984-01-01

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

Neutron diffraction studies of the Na-ion battery electrode materials NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3}

Energy Technology Data Exchange (ETDEWEB)

Yahia, H. Ben [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P.O. Box 5825 Doha (Qatar); Essehli, R., E-mail: ressehli@qf.org.qa [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P.O. Box 5825 Doha (Qatar); Avdeev, M. [Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights NSW 2234 (Australia); Park, J-B.; Sun, Y-K. [Department of Energy Engineering Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Al-Maadeed, M.A. [Center for Advanced Materials (CAM), Qatar University, 2713 Doha (Qatar); Belharouak, I., E-mail: ibelharouak@qf.org.qa [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P.O. Box 5825 Doha (Qatar)

2016-06-15

The new compounds NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} were synthesized by sol-gel method and their crystal structures were determined by using neutron powder diffraction data. These compounds were characterized by galvanometric cycling and cyclic voltammetry. NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} crystallize with a stuffed α-CrPO{sub 4}-type structure. The structure consists of a 3D-framework made of octahedra and tetrahedra that are sharing corners and/or edges generating channels along [100] and [010], in which the sodium atoms are located. Of significance, in the structures of NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} a statistical disorder Ni{sup 2+}/Cr{sup 3+} was observed on both the 8g and 4a atomic positions, whereas in NaCoCr{sub 2}(PO{sub 4}){sub 3} the statistical disorder Co{sup 2+}/Cr{sup 3+} was only observed on the 8g atomic position. When tested as negative electrode materials, NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} delivered specific capacities of 352, 385, and 368 mA h g{sup −1}, respectively, which attests to the electrochemical activity of sodium in these compounds. - Highlights: • NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} were synthesized by sol-gel method. • The crystal structures were determined by using neutron powder diffraction data. • The three compounds crystallize with a stuffed α-CrPO{sub 4}-type structure. • The three compounds were tested as anodes in sodium-ion batteries. • Relatively high specific capacities were obtained for these compounds.

A convenient route to N-acetyl-D-glucosamine-2-C-d and N-acetyl-D-mannosamine-2-C-d

International Nuclear Information System (INIS)

Szilagyi, L.; Bujtas, G.

1977-01-01

Title compounds were prepared through epimerisation of 2-acetamido-2-deoxy-D-glucose in NaOD. The isotopic purity of the products was determined by NMR and mass spectroscopy. The mechanism of epimerisation is briefly discussed. (orig.) [de

Inhibition of radiation-induced DNA strand breaks by hoechst 33258: OH-radical scavenging and DNA radical quenching

International Nuclear Information System (INIS)

Adhikary, A.; Bothe, E.; Von Sonntag, C.; Adhikary, A.

1997-01-01

The minor-groove-binding dye Hoechst 33258 has been found to protect pBR322 DNA in aqueous solution against radiation-induced single-strand breaks (ssb). This protective effect has been assumed to be largely due to the scavenging of the strand-break-generating OH radicals by Hoechst. From D 37 values for ssb at different Hoechst concentrations the value of the OH radical scavenging constant of DNA-bound Hoechst has been estimated at k Ho/DNA = 2.7 * 10 11 dm 3 mol -1 . This unexpectedly high value has led us to study the reactions of OH radicals with Hoechst in the absence and in the presence of double-stranded calf thymus DNA (ds DNA) by pulse radiolysis, and the formation of radiation-induced ssb by low angle laser light scattering. The D 37 /D 37 0 values at different Hoechst concentrations agree with the values obtained by Martin and al. and demonstrate the protection. However, this protection cannot be explained on the basis of OH radical scavenging alone using the above rate constants. There must, in addition, be some quenching of DNA radicals. Hoechst radicals are formed in the later ms time range, i.e a long time after the disappearance of the OH radicals. This delayed Hoechst radical formation has been assigned to a a reaction of DNA radicals with Hoechst, thereby inhibiting strand breakage. In confirmation, pulse radiolysis of aqueous solution of nucleotides in the presence of Hoechst yields a similar delayed Hoechst radical formation. The data indicate that in DNA the cross-section of this quenching has a diameter of 3 to 4 base pairs per Hoechst molecule. (N.C.)

Radiation damage to human erythrocytes. Relative contribution of hydroxyl and chloride radicals in N{sub 2}O-saturated buffers

Energy Technology Data Exchange (ETDEWEB)

Krokosz, Anita [Department of Molecular Biophysics, University of Lodz, Banacha 12/16, 90 237 Lodz (Poland)], E-mail: krokosz@biol.uni.lodz.pl; Komorowska, Magdalena A.; Szweda-Lewandowska, Zofia [Department of Molecular Biophysics, University of Lodz, Banacha 12/16, 90 237 Lodz (Poland)

2008-06-15

The erythrocyte suspensions in Na-phosphate buffered isotonic NaCl solution (PBS) or Na-phosphate isotonic buffer (PB) (hematocrit 1%) were irradiated with the dose of 400 Gy under N{sub 2}O. Erythrocytes were incubated in the medium in which the cells were irradiated or in fresh PBS. The level of damage to cells was estimated on the basis of the course of post-radiation hemolysis and hemoglobin (Hb) oxidation. The medium in which the cells were irradiated and incubated influenced the course of the post-radiation hemolysis and Hb oxidation as well as some other parameters. We discussed the contribution of hydroxyl and chloride radicals in the initiation of erythrocyte damage and oxygen modification of these processes.

End-Functionalized Poly(N-isopropylacrylamide with d-Glucosamine through Different Initiator from C-1 and C-2 Positions via Atom Transfer Radical Polymerization

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Guihua Cui

2016-11-01

Full Text Available Regioselective modification of d-glucosamine (2-amino-2-deoxy-d-glucopyranose, GA through C-1 and C-2 positions to synthesized thermo-responsive D-Glucosamine-poly(N-iso-propylacrylamide (PNIPAM via atom transfer radical polymerization (ATRP was investigated for the first time. Two different schemes of the synthesis for GA derivatives (GA-PNIPAM (i and (ii with well-defined structures using 3,4,6-tri-o-acetyl-2-deoxy-2-phthalimido-β-d-glucopyranose and 1,3,4,6-tetra-o-acetyl-2-amino-2-deoxy-β-d-glucopyranose intermediates were examined. The GA-PNIPAM (ii had an amino at C-2 position, while there was a hydroxyl in GA-PNIPAM (i at this position. Both the resulting oligomers (i and (ii had a narrow dispersity, and no significant cytotoxic response of copolymers (i and (ii was observed in the cell line over the concentration range from 0.1 μg/mL to 1000 μg/mL at any of the exposure times. In addition, it was discovered that GA-PNIPAM (i and (ii inhibited the proliferation of Human Hepatocellular Carcinoma Cells HepG2 as the concentration and the time changed, and the inhibitory activity of polymer (ii was higher than that of he (i. The results suggest that the GA-PNIPAM polymers show excellent biocompatibility in vitro.

Free radical behaviours during methylene blue degradation in the Fe2+/H2O2 system.

Science.gov (United States)

Wang, Zhonghua; Zhao, Haiqian; Qi, Hanbing; Liu, Xiaoyan; Liu, Yang

2017-12-22

Behaviours of the free radicals during the methylene blue (MB) oxidation process in the Fe 2+ /H 2 O 2 system were studied to reveal the reason for the low utilization efficiency of H 2 O 2 . The roles of [Formula: see text], [Formula: see text] and [Formula: see text] radicals were proven to be different in the MB oxidation process. The results showed that [Formula: see text] radicals had a strong ability to oxidize MB; however, they were not the main active substances for MB degradation due to the low concentration in the traditional Fe 2+ /H 2 O 2 system. [Formula: see text] radicals could not oxidize MB. [Formula: see text] radicals were the main active substances for MB oxidation. In the short initial stage, the utilization efficiency of H 2 O 2 was high, because the generation rate of [Formula: see text] was much higher than that of [Formula: see text]. More [Formula: see text] radicals were involved in the MB oxidation reaction. In the long deceleration stage (after the short initial stage), a large amount of H 2 O 2 was consumed, but the amount of oxidized MB was very small. Most of the [Formula: see text] radicals were consumed via the rapid useless reaction between [Formula: see text] and [Formula: see text] in this stage, resulting in the serious useless consumption of H 2 O 2 . It is a feasible method to improve the utilization efficiency of H 2 O 2 by adding suitable additives into the Fe 2+ /H 2 O 2 system to weaken the useless reaction between [Formula: see text] and [Formula: see text].

Temperature Dependent Rate Coefficients for the Gas-Phase Reaction of the OH Radical with Linear (L2, L3) and Cyclic (D3, D4) Permethylsiloxanes.

Science.gov (United States)

Bernard, François; Papanastasiou, Dimitrios K; Papadimitriou, Vassileios C; Burkholder, James B

2018-04-19

Permethylsiloxanes are emitted into the atmosphere during production and use as personal care products, lubricants, and cleaning agents. The predominate atmospheric loss process for permethylsiloxanes is expected to be via gas-phase reaction with the OH radical. In this study, rate coefficients, k(T), for the OH radical gas-phase reaction with the two simplest linear and cyclic permethylsiloxanes were measured using a pulsed laser photolysis-laser induced fluorescence technique over the temperature range of 240-370 K and a relative rate method at 294 K: hexamethyldisiloxane ((CH 3 ) 3 SiOSi(CH 3 ) 3 , L 2 ), k 1 ; octamethyltrisiloxane ([(CH 3 ) 3 SiO] 2 Si(CH 3 ) 2 , L 3 ), k 2 ; hexamethylcyclotrisiloxane ([-Si(CH 3 ) 2 O-] 3 , D 3 ), k 3 ; and octamethylcyclotetrasiloxane ([-Si(CH 3 ) 2 O-] 4 , D 4 ), k 4 . The obtained k(294 K) values and temperature-dependence expressions for the 240-370 K temperature range are (cm 3 molecule -1 s -1 , 2σ absolute uncertainties): k 1 (294 K) = (1.28 ± 0.08) × 10 -12 , k 1 ( T) = (1.87 ± 0.18) × 10 -11 exp(-(791 ± 27)/ T); k 2 (294 K) = (1.72 ± 0.10) × 10 -12 , k 2 ( T) = 1.96 × 10 -13 (T/298) 4.34 exp(657/ T); k 3 (294 K) = (0.82 ± 0.05) × 10 -12 , k 3 ( T) = (1.29 ± 0.19) × 10 -11 exp(-(805 ± 43)/ T); and k 4 (294 K) = (1.12 ± 0.10) × 10 -12 , k 4 ( T) = (1.80 ± 0.26) × 10 -11 exp(-(816 ± 43)/ T). The cyclic molecules were found to be less reactive than the analogous linear molecule with the same number of -CH 3 groups, while the linear and cyclic permethylsiloxane reactivity both increase with the increasing number of CH 3 - groups. The present results are compared with previous rate coefficient determinations where available. The permethylsiloxanes included in this study are atmospherically short-lived compounds with estimated atmospheric lifetimes of 11, 8, 17, and 13 days, respectively.

Visible-Light-Mediated Excited State Relaxation in Semi-Synthetic Genetic Alphabet: d5SICS and dNaM.

Science.gov (United States)

Bhattacharyya, Kalishankar; Datta, Ayan

2017-08-25

The excited state dynamics of an unnatural base pair (UBP) d5SICS/dNaM were investigated by accurate ab-initio calculations. Time-dependent density functional and high-level multireference calculations (MS-CASPT2) were performed to elucidate the excitation of this UBP and its excited state relaxation mechanism. After excitation to the bright state S 2 (ππ*), it decays to the S 1 state and then undergoes efficient intersystem crossing to the triplet manifold. The presence of sulfur atom in d5SICS leads to strong spin-orbit coupling (SOC) and a small energy gap that facilitates intersystem crossing from S 1 (n s π*) to T 2 (ππ*) followed by internal conversion to T 1 state. Similarly in dNaM, the deactivation pathway follows analogous trends. CASPT2 calculations suggest that the S 1 (ππ*) state is a dark state below the accessible S 2 (ππ*) bright state. During the ultrafast deactivation, it exhibits bond length inversion. From S 1 state, significant SOC leads the population transfer to T 3 due to a smaller energy gap. Henceforth, fast internal conversion occurs from T 3 to T 2 followed by T 1 . From time-dependent trajectory surface hopping dynamics, it is found that excited state relaxation occurs on a sub-picosecond timescale in d5SICS and dNaM. Our findings strongly suggest that there is enough energy available in triplet state of UBP to generate reactive oxygen species and induce phototoxicity with respect to cellular DNA. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-assembled decanuclear Na(I)2Mn(II)4Mn(III)4 complexes: from discrete clusters to 1-D and 2-D structures, with the Mn(II)4Mn(III)4 unit displaying a large spin ground state and probable SMM behaviour.

Science.gov (United States)

Langley, Stuart K; Chilton, Nicholas F; Moubaraki, Boujemaa; Murray, Keith S

2011-12-07

The synthesis, magnetic characterization and X-ray crystal structures are reported for five new manganese compounds, [Mn(III)(teaH(2))(sal)]·(1/2)H(2)O (1), [Na(I)(2)Mn(II)(4)Mn(III)(4)(teaH)(6)(sal)(4)(N(3))(2)(MeOH)(4)]·6MeOH (2), [Na(I)(2)Mn(II)(4)Mn(III)(4)(teaH)(6)(sal)(4)(N(3))(2)(MeOH)(2)](n)·7MeOH (3), [Na(I)(2)Mn(II)(4)Mn(III)(4)(teaH)(6)(sal)(4)(N(3))(2)(MeOH)(2)](n)·2MeOH·Et(2)O (4) and [K(I)(2)Mn(II)(4)Mn(III)(4)(teaH)(6)(sal)(4)(N(3))(2)(H(2)O)(2)](n)·5MeOH (5). Complex 1 is a mononuclear compound, formed via the reaction of Mn(NO(3))(2)·4H(2)O, triethanolamine (teaH(3)) and salicylic acid (salH(2)) in a basic methanolic solution. Compound 2 is a mixed-valent hetero-metallic cluster made up of a Mn(8)Na(2) decanuclear core and is formed via the reaction of sodium azide (NaN(3)) with 1. Compounds 3-5 are isolated as 1- or 2-D coordination polymers, each containing the decanuclear Mn(8)M(2) (M = Na(+) or K(+)) core building block as the repeating unit. Compound 3 is isolated when 1 is reacted with NaN(3) over a very short reaction time and forms a 1-D coordination polymer. Each unit displays inter-cluster bridges via the O-atoms of teaH(2-) ligands bonding to the sodium ions of an adjacent cluster. Increasing the reaction time appears to drive the formation of 4 which forms 2-D polymeric sheets and is a packing polymorph of 3. The addition of KMnO(4) and NaN(3) to 1 resulted in compound 5, which also forms a 1-D coordination polymer of the decanuclear core unit. The 1-D chains are now linked via inter-cluster potassium and salicylate bridges. Solid state DC susceptibility measurements were performed on compounds 1-5. The data for 1 are as expected for an S = 2 Mn(III) ion, with the isothermal M vs. H data being fitted by matrix diagonalization methods to give values of g and the axial (D) and rhombic (E) zero field splitting parameters of 2.02, -2.70 cm(-1) and 0.36 cm(-1) respectively. The data for 2-5, each with an identical Mn(II)(4)Mn(III)(4

The herbicide 2,4-dichlorophenoxyacetic acid induces the generation of free-radicals and associated oxidative stress responses in yeast

International Nuclear Information System (INIS)

Teixeira, Miguel C.; Telo, Joao P.; Duarte, Nuno F.; Sa-Correia, Isabel

2004-01-01

The pro-oxidant action of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) is demonstrated in this study using Saccharomyces cerevisiae as a eukaryotic experimental model. Evidence is presented for the generation of hydroxyl-radicals, in yeast cells suddenly exposed to 2,4-D, detected by in vivo electron paramagnetic resonance (EPR) spectroscopy using 5,5'-dimethyl-1-pyrroline N-oxide and 5-tert-butoxycarbonyl-5-methyl-1-pyrroline N-oxide as spin-traps. The intensity of the EPR spectra was dependent on the concentration of herbicide tested and was consistently higher in a mutant (Δsod1) devoid of the cytosolic CuZn-superoxide dismutase. A time-course-dependent variation of the level of free-radical adducts was registered upon sudden exposure of an yeast cell population to concentrations of 2,4-D that lead to an initial period of viability loss, before resumption of inhibited growth by the viable adapted population. The variation pattern of the level of hydroxyl-radical adducts correlated with the one determined for the activity of Sod1p, cytosolic catalase Ctt1p, and the dithiol glutaredoxins Grx1p and Grx2p

Behaviorismo radical e discurso pós-moderno

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José Antônio Damásio Abib

Full Text Available Argumenta-se neste ensaio que o behaviorismo radical não apoia nenhum destes pressupostos do discurso moderno: fundacionismo na epistemologia, representacionismo na linguagem e as metanarrativas do progresso do Ocidente. Argumenta-se ainda que o behaviorismo radical é solidário com estas tendências do discurso pós-moderno: pragmatismo epistemológico, anti-representacionismo na linguagem e dissolução das metanarrativas do progresso científico, social, político e cultural do Ocidente. Sugere-se, finalmente, que o pensamento de Skinner rompe decisivamente com o discurso moderno e aproxima-se do discurso pós-moderno.

Evidence that Na+-pumping occurs through the D-channel in Vitreoscilla cytochrome bo

International Nuclear Information System (INIS)

Kim, Seong K.; Stark, Benjamin C.; Webster, Dale A.

2005-01-01

The operon (cyo) encoding the Na + -pumping respiratory terminal oxidase (cytochrome bo) of the bacterium Vitreoscilla was transformed into Escherichia coli GV100, a deletion mutant of cytochrome bo. This was done for the wild type operon and five mutants in three conserved Cyo subunit I amino acids known to be crucial for H + transport in the E. coli enzyme, one near the nuclear center, one in the K-channel, and one in the D-channel. CO-binding, NADH and ubiquinol oxidase, and Na + -pumping activities were all substantially inhibited by each mutation. The wild type Vitreoscilla cytochrome bo can pump Na + against a concentration gradient, resulting in a transmembrane concentration differential of 2-3 orders of magnitude. It is proposed that Vitreoscilla cytochrome bo pumps four Na + through the D-channel to the exterior and transports four H + through the K-channel for the reduction of each O 2

EPR study of gamma irradiated N-methyl taurine (C 3H 9NO 3S) and sodium hydrogen sulphate monohydrate (NaHSO 3·H 2O) single crystals

Science.gov (United States)

Yıldırım, İlkay; Karabulut, Bünyamin

2011-03-01

EPR study of gamma irradiated C 3H 9NO 3S and NaHSO 3.H 2O single crystals have been carried out at room temperature. There is one site for the radicals in C 3H 9NO 3S and two magnetically distinct sites for the radicals in NaHSO 3. The observed lines in the EPR spectra have been attributed to the species of SO3- and RH radicals for N-methyl taurine, and to the SO3- and OH radicals for sodium hydrogen sulfate monohydrate single crystals. The principal values of the g for SO3-, the hyperfine values of RH and OH proton splitting have been calculated and discussed.

Crystal structure of the sodium cobaltate deuterate superconductor NaxCoO2·4xD2O (x≅(1/3))

International Nuclear Information System (INIS)

Jorgensen, J.D.; Avdeev, M.; Hinks, D.G.; Burley, J.C.; Short, S.

2003-01-01

Neutron and x-ray powder diffraction have been used to investigate the crystal structures of a sample of the newly-discovered superconducting sodium cobaltate deuterate compound with composition Na 0.31(3) CoO 2 ·1.25(2)D 2 O and its anhydrous parent compound Na 0.61(1) CoO 2 . The anhydrous parent compound Na 0.61(1) CoO 2 has two partially occupied Na sites sandwiched, in the same plane, between CoO 2 layers. When Na is removed to make the superconducting composition, the Na site that experiences the strongest Na-Co repulsion is emptied while the occupancy of the other Na site is reduced to about one third. The deuterate superconducting compound is formed by coordinating four D 2 O molecules (two above and two below) to each remaining Na ion in a way that gives Na-O distances nearly equal to those in the parent compound. One deuteron of the D 2 O molecule is hydrogen bonded to an oxygen atom in the CoO 2 plane and the oxygen atom and the second deuteron of each D 2 O molecule lie approximately in a plane between the Na layer and the CoO 2 layers. This coordination of Na by four D 2 O molecules leads in a straightforward way to ordering of the Na ions and D 2 O molecules consistent with the observation of additional shorter-range scattering features in the diffraction data. The sample studied here, which has T c =4.5 K, has a refined composition of Na 0.31(3) CoO 2 ·1.25(2)D 2 O, in agreement with the expected 1:4 ratio of Na to D 2 O. These results show that the optimal superconducting composition should be viewed as a specific hydrated compound, not a solid solution of Na and D 2 O (H 2 O) in Na x CoO 2 ·D 2 O. The hydrated superconducting compound may be stable over a limited range of Na and D 2 O concentration, but studies of T c and other physical properties vs Na or D 2 O composition should be viewed with caution until it is verified that the compound remains in the same phase over the composition range of the study

Direct Detection of Unnatural DNA Nucleotides dNaM and d5SICS using the MspA Nanopore.

Directory of Open Access Journals (Sweden)

Jonathan M Craig

Full Text Available Malyshev et al. showed that the four-letter genetic code within a living organism could be expanded to include the unnatural DNA bases dNaM and d5SICS. However, verification and detection of these unnatural bases in DNA requires new sequencing techniques. Here we provide proof of concept detection of dNaM and d5SICS in DNA oligomers via nanopore sequencing using the nanopore MspA. We find that both phi29 DNA polymerase and Hel308 helicase are capable of controlling the motion of DNA containing dNaM and d5SICS through the pore and that single reads are sufficient to detect the presence and location of dNaM and d5SICS within single molecules.

Thermal expansion and temperature variation of elastic constants of Li(H,D) and Na(H,D) systems

International Nuclear Information System (INIS)

Islam, A.K.M.A.; Hoque, M.T.

1994-11-01

An analysis of thermal expansion of Li(H,D) systems up to melting temperature has been performed using the theory of anharmonic lattice. The study has for the first time been extended to Na(H,D) systems where very little or no data are available. The calculated lattice constants of Li(H,D) systems show quite good agreement with experiment. The success of the present calculation with Li(H,D) and room temperature lattice constant data for Na(H,D) given an indication of the reliability of the computed lattice constants and thermal expansion coefficients for Na(H,D) systems. The study also allows us to predict the hitherto unknown lattice constants of Na(H,D) crystal at 0K. The temperature dependence of elastic constants for Li(H,D) systems has also been evaluated. Comparison with measurements shows the reliability of the present calculations. (author). 45 refs, 4 figs

Reorientation dynamics of cyclohexadienyl radicals in zeolites

International Nuclear Information System (INIS)

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

1997-01-01

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

Crystal structure of the sodium cobaltate deuterate superconductor NaxCoO2ṡ4xD2O (x≈1/3)

Science.gov (United States)

Jorgensen, J. D.; Avdeev, M.; Hinks, D. G.; Burley, J. C.; Short, S.

2003-12-01

Neutron and x-ray powder diffraction have been used to investigate the crystal structures of a sample of the newly-discovered superconducting sodium cobaltate deuterate compound with composition Na0.31(3)CoO2ṡ1.25(2)D2O and its anhydrous parent compound Na0.61(1)CoO2. The anhydrous parent compound Na0.61(1)CoO2 has two partially occupied Na sites sandwiched, in the same plane, between CoO2 layers. When Na is removed to make the superconducting composition, the Na site that experiences the strongest Na Co repulsion is emptied while the occupancy of the other Na site is reduced to about one third. The deuterate superconducting compound is formed by coordinating four D2O molecules (two above and two below) to each remaining Na ion in a way that gives Na O distances nearly equal to those in the parent compound. One deuteron of the D2O molecule is hydrogen bonded to an oxygen atom in the CoO2 plane and the oxygen atom and the second deuteron of each D2O molecule lie approximately in a plane between the Na layer and the CoO2 layers. This coordination of Na by four D2O molecules leads in a straightforward way to ordering of the Na ions and D2O molecules consistent with the observation of additional shorter-range scattering features in the diffraction data. The sample studied here, which has Tc=4.5 K, has a refined composition of Na0.31(3)CoO2ṡ1.25(2)D2O, in agreement with the expected 1:4 ratio of Na to D2O. These results show that the optimal superconducting composition should be viewed as a specific hydrated compound, not a solid solution of Na and D2O (H2O) in NaxCoO2ṡD2O. The hydrated superconducting compound may be stable over a limited range of Na and D2O concentration, but studies of Tc and other physical properties vs Na or D2O composition should be viewed with caution until it is verified that the compound remains in the same phase over the composition range of the study.

Presence of hydrogen peroxide, a source of hydroxyl radicals, in acid electrolyzed water.

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Takayuki Mokudai

Full Text Available BACKGROUND: Acid electrolyzed water (AEW, which is produced through the electrolysis of dilute sodium chloride (NaCl or potassium chloride solution, is used as a disinfectant in various fields because of its potent antimicrobial activity. The hydroxyl radical, an oxygen radical species, is often suggested as a putative active ingredient for AEW antimicrobial activity. METHODOLOGY/PRINCIPAL FINDINGS: The aim of the present study is to detect hydroxyl radicals in AEW. The hydroxyl radicals in AEW prepared under different conditions were determined using an electron spin resonance (ESR technique. A signal from 5,5-dimethyl-1-pyrroline N-oxide (DMPO-OH, an adduct of DMPO and the hydroxyl radical, was detected in AEW prepared by double or triple electrolyses of 1% NaCl but not of 0.1% NaCl solution. Then the presence of hydrogen peroxide as a proposed source of hydroxyl radicals was examined using a combination of ESR and a Fenton reaction. The DMPO-OH signal was clearly detected, even in AEW prepared by single electrolysis of 0.1% NaCl solution, when ferrous sulfate was added to induce a Fenton reaction, indicating the presence of hydrogen peroxide in the AEW. Since sodium formate, a hydroxyl radical scavenger, did not affect the bactericidal activity of AEW, it is concluded that the radical is unlikely to contribute to the antimicrobial activity of AEW, although a small amount of the radical is produced from hydrogen peroxide. Dimethyl sulfoxide, the other hydroxyl radical scavenger used in the present study, canceled the bactericidal activity of AEW, accompanied by complete depletion of free available chlorine, suggesting that hypochlorous acid is probably a major contributor to the antimicrobial activity. CONCLUSIONS: It is strongly suggested that although hydrogen peroxide is present in AEW as a source of hydroxyl radicals, the antimicrobial activity of AEW does not depend on these radicals.

The reactions of SO3 with HO2 radical and H2O...HO2 radical complex. Theoretical study on the atmospheric formation of HSO5 and H2SO4.

Science.gov (United States)

Gonzalez, Javier; Torrent-Sucarrat, Miquel; Anglada, Josep M

2010-03-07

The influence of a single water molecule on the gas-phase reactivity of the HO(2) radical has been investigated by studying the reactions of SO(3) with the HO(2) radical and with the H(2)O...HO(2) radical complex. The naked reaction leads to the formation of the HSO(5) radical, with a computed binding energy of 13.81 kcal mol(-1). The reaction with the H(2)O...HO(2) radical complex can give two different products, namely (a) HSO(5) + H(2)O, which has a binding energy that is computed to be 4.76 kcal mol(-1) more stable than the SO(3) + H(2)O...HO(2) reactants (Delta(E + ZPE) at 0K) and an estimated branching ratio of about 34% at 298K and (b) sulfuric acid and the hydroperoxyl radical, which is computed to be 10.51 kcal mol(-1) below the energy of the reactants (Delta(E + ZPE) at 0K), with an estimated branching ratio of about 66% at 298K. The fact that one of the products is H(2)SO(4) may have relevance in the chemistry of the atmosphere. Interestingly, the water molecule acts as a catalyst, [as it occurs in (a)] or as a reactant [as it occurs in (b)]. For a sake of completeness we have also calculated the anharmonic vibrational frequencies for HO(2), HSO(5), the HSO(5)...H(2)O hydrogen bonded complex, H(2)SO(4), and two H(2)SO(4)...H(2)O complexes, in order to help with the possible experimental identification of some of these species.

LATOUCHE, Serge. Cornelius Castoriadis ou l’autonomie radical. Colección: Les précurseurs de la décoissance. Neuvy-en-Champagne. Le passager Clandestin. ISBN: 978-2-36935-008-8.

Directory of Open Access Journals (Sweden)

EMILIANO ALDEGANI

2015-06-01

Full Text Available LATOUCHE, Serge. Cornelius Castoriadis ou l’autonomie radical.Colección: Les précurseurs de la décoissance. Neuvy-en-Champagne. Le passager Clandestin. ISBN: 978-2-36935-008-8.

Applied quantum chemistry: Spectroscopic detection and characterization of the F2BS and Cl2BS free radicals in the gas phase

International Nuclear Information System (INIS)

Jin, Bing; Clouthier, Dennis J.; Sheridan, Phillip M.

2015-01-01

In this and previous work [D. J. Clouthier, J. Chem. Phys. 141, 244309 (2014)], the spectroscopic signatures of the X 2 BY (X = H, halogen, Y = O, S) free radicals have been predicted using high level ab initio theory. The theoretical results have been used to calculate the electronic absorption and single vibronic level (SVL) emission spectra of the radicals under typical jet-cooled conditions. Using these diagnostic predictions, the previously unknown F 2 BS and Cl 2 BS free radicals have been identified and characterized. The radicals were prepared in a free jet expansion by subjecting precursor mixtures of BF 3 or BCl 3 and CS 2 vapor to an electric discharge at the exit of a pulsed molecular beam valve. The B ~2 A 1 –X ~ 2 B 2 laser-induced fluorescence spectra were found within 150 cm −1 of their theoretically predicted positions with vibronic structure consistent with our Franck-Condon simulations. The B ~2 A 1 state emits down to the ground state and to the low-lying A ~2 B 1 excited state and the correspondence between the observed and theoretically derived SVL emission Franck-Condon profiles was used to positively identify the radicals and make assignments. Excited state Coriolis coupling effects complicate the emission spectra of both radicals. In addition, a forbidden component of the electronically allowed B ~ –X ~ band system of Cl 2 BS is evident, as signaled by the activity in the b 2 modes in the spectrum. Symmetry arguments indicate that this component gains intensity due to a vibronic interaction of the B ~2 A 1 state with a nearby electronic state of 2 B 2 symmetry

Electron paramagnetic relaxation studies of free radicals in. gamma. -irradiated DNA

Energy Technology Data Exchange (ETDEWEB)

Kuwabara, M; Yoshi, G [Hokkaido Univ., Sapporo (Japan)

1980-01-01

Using the continuous microwave power saturation method the T/sub 1/ spin-lattice relaxation time and T/sub 2/ spin-spin relaxation time for DNA radicals (measured at 297/sup 0/K) are reported. Identical experiments carried out on thymidine-5'-monophosphate sodium salt (TMP) and deoxycytidine-5'-monophosphate sodium salt (dCMP) are also reported. Irradiated DNA produces TMP radicals on the base moiety and dCMP radicals on the sugar moiety. Comparing the relaxation times of DNA with those of TMP and dCMP provided a reliable analysis of the nature of DNA radicals.

Double C-H activation of ethane by metal-free SO2*+ radical cations.

Science.gov (United States)

de Petris, Giulia; Cartoni, Antonella; Troiani, Anna; Barone, Vincenzo; Cimino, Paola; Angelini, Giancarlo; Ursini, Ornella

2010-06-01

The room-temperature C-H activation of ethane by metal-free SO(2)(*+) radical cations has been investigated under different pressure regimes by mass spectrometric techniques. The major reaction channel is the conversion of ethane to ethylene accompanied by the formation of H(2)SO(2)(*+), the radical cation of sulfoxylic acid. The mechanism of the double C-H activation, in the absence of the single activation product HSO(2)(+), is elucidated by kinetic studies and quantum chemical calculations. Under near single-collision conditions the reaction occurs with rate constant k=1.0 x 10(-9) (+/-30%) cm(3) s(-1) molecule(-1), efficiency=90%, kinetic isotope effect k(H)/k(D)=1.1, and partial H/D scrambling. The theoretical analysis shows that the interaction of SO(2)(*+) with ethane through an oxygen atom directly leads to the C-H activation intermediate. The interaction through sulfur leads to an encounter complex that rapidly converts to the same intermediate. The double C-H activation occurs by a reaction path that lies below the reactants and involves intermediates separated by very low energy barriers, which include a complex of the ethyl cation suitable to undergo H/D scrambling. Key issues in the observed reactivity are electron-transfer processes, in which a crucial role is played by geometrical constraints. The work shows how mechanistic details disclosed by the reactions of metal-free electrophiles may contribute to the current understanding of the C-H activation of ethane.

Generation of radicals and antimalarial activity of dispiro-1,2,4-trioxolanes

Science.gov (United States)

Denisov, E. T.; Denisova, T. G.

2013-01-01

The kinetic schemes of the intramolecular oxidation of radicals generated from substituted dispiro-1,2,4-trioxolanes (seven compounds) in the presence of Fe2+ and oxygen were built. Each radical reaction was defined in terms of enthalpy, activation energy, and rate constant. The kinetic characteristics were calculated by the intersecting parabolas method. The competition between the radical reactions was considered. The entry of radicals generated by each compound into the volume was calculated. High antimalarial activity was found for 1,2,4-trioxolanes, which generated hydroxyl radicals. The structural features of trioxolanes responsible for the generation of hydroxyl radicals were determined.

Theoretical description of spin-selective reactions of radical pairs diffusing in spherical 2D and 3D microreactors

International Nuclear Information System (INIS)

Ivanov, Konstantin L.; Lukzen, Nikita N.; Sadovsky, Vladimir M.

2015-01-01

In this work, we treat spin-selective recombination of a geminate radical pair (RP) in a spherical “microreactor,” i.e., of a RP confined in a micelle, vesicle, or liposome. We consider the microreactor model proposed earlier, in which one of the radicals is located at the center of the micelle and the other one undergoes three-dimensional diffusion inside the micelle. In addition, we suggest a two-dimensional model, in which one of the radicals is located at the “pole” of the sphere, while the other one diffuses on the spherical surface. For this model, we have obtained a general analytical expression for the RP recombination yield in terms of the free Green function of two-dimensional diffusion motion. In turn, this Green function is expressed via the Legendre functions and thus takes account of diffusion over a restricted spherical surface and its curvature. The obtained expression allows one to calculate the RP recombination efficiency at an arbitrary magnetic field strength. We performed a comparison of the two models taking the same geometric parameters (i.e., the microreactor radius and the closest approach distance of the radicals), chemical reactivity, magnetic interactions in the RP and diffusion coefficient. Significant difference between the predictions of the two models is found, which is thus originating solely from the dimensionality effect: for different dimensionality of space, the statistics of diffusional contacts of radicals becomes different altering the reaction yield. We have calculated the magnetic field dependence of the RP reaction yield and chemically induced dynamic nuclear polarization of the reaction products at different sizes of the microreactor, exchange interaction, and spin relaxation rates. Interestingly, due to the intricate interplay of diffusional contacts of reactants and spin dynamics, the dependence of the reaction yield on the microreactor radius is non-monotonous. Our results are of importance for (i) interpreting

Isolation and characterization of ScGluD2, a new sugarcane beta-1,3-glucanase D family gene induced by Sporisorium scitamineum, ABA, H2O2, NaCl, and CdCl2 stresses

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Yachun Su

2016-09-01

Full Text Available Beta-1,3-glucanases (EC 3.2.1.39, commonly known as pathogenesis-related (PR proteins, play an important role not only in plant defense against fungal pathogens but also in plant physiological and developmental processes. However, only a limited number of sugarcane beta-1,3-glucanase genes have been isolated. In the present study, we identified and characterized a new beta-1,3-glucanase gene ScGluD2 (GenBank Acc No. KF664181 from sugarcane. An X8 domain was present at the C terminal region of ScGluD2, suggesting beta-1,3-glucan-binding function. Phylogenetic analysis showed that the predicted ScGluD2 protein was classified into subfamily D beta-1,3-glucanase. Localization of the ScGluD2 protein in the plasma membrane was determined by tagging it with green fluorescent protein. The expression of ScGluD2 was more up-regulated in sugarcane smut-resistant cultivars in the early stage (1 d or 3 d than in the susceptible ones after being challenged by the smut pathogen, revealing that ScGluD2 may be involved in defense against the invasion of Sporisorium scitamineum. Transient overexpression of ScGluD2 in Nicotiana benthamiana leaves induced a defense response and exhibited antimicrobial action on the tobacco pathogens Pseudomonas solanacearum and Botrytis cinerea, further demonstrating that ScGluD2 was related to the resistance to plant pathogens. However, the transcripts of ScGluD2 partially increased (12 h under NaCl stress, and were steadily up-regulated from 6 h to 24 h upon ABA, H2O2, and CdCl2 treatments, suggesting that ABA may be a signal molecule regulating oxidative stress and play a role in the salt and heavy metal stress-induced stimulation of ScGluD2 transcripts. Taken together, ScGluD2, a novel member of subfamily D beta-1,3-glucanase, was a stress-related gene of sugarcane involved in plant defense against smut pathogen attack and salt and heavy metal stresses.

Two-photon laser-induced fluorescence studies of HS radicals, DS radicals, and I atoms

Energy Technology Data Exchange (ETDEWEB)

Tiee, J J; Ferris, M J; Loge, G W; Wampler, F B

1983-04-15

A two-photon laser-induced excitation and fluorescence technique has been used to study the A /sup 2/..sigma../sup +/ - X/sup 2/PI transition of HS and DS radicals and various high-lying /sup 4/P/sup 0/, /sup 2/D/sup 0/, and /sup 4/D/sup 0/ states of the I atom. The two-photon excitation cross sections and detection sensitivity are discussed. 13 references, 5 figures.

Experimental determination of the H2O + 15 wt% NaCl and H2O + 25 wt% NaCl liquidi to 1.4 GPa

Science.gov (United States)

Valenti, P.; Schmidt, C.

2009-12-01

1380 MPa, 12.7°C for 25 wt% NaCl. At lower pressures (except at 0.1 MPa and 15 wt%NaCl), the last solid was hydrohalite. Hydrohalite was identified based on crystal shape, its higher density and index of refraction relative to those of the liquid, and Raman spectra. For both bulk compositions, the liquidus displayed negative dP/dT slopes to ~100 MPa, and positive dP/dT slopes above that pressure. The transition from negative to positive dP/dT slopes occurred without a change of the liquidus solid (hydrohalite), which suggests a relationship to anomalous properties of the aqueous liquid. This finding is consistent with literature data for the halite liquidus of H2O + 40 wt% NaCl (Schmidt et al. 1998). Generally, addition of NaCl steepens the liquidi. The dP/dT slopes of the ice VI liquidus of the 15 and 25 wt% NaCl solutions obtained in this study are steeper than that of the ice VI melting curve of pure water (Wagner et al. 1994), but shallower than reported for a H2O + 5.5 wt% NaCl solution (Manning and Daniel 2008).

Radical decomposition of 2,4-dinitrotoluene (DNT at conditions of advanced oxidation. Computational study

Directory of Open Access Journals (Sweden)

Liudmyla K. Sviatenko

2016-12-01

Full Text Available At the present time one of the main remediation technologies for such environmental pollutant as 2,4-dinitrotoluene (DNT is advanced oxidation processes (AOPs. Since hydroxyl radical is the most common active species for AOPs, in particular for Fenton oxidation, the study modeled mechanism of interaction between DNT and hydroxyl radical at SMD(Pauling/M06-2X/6-31+G(d,p level. Computed results allow to suggest the most energetically favourable pathway for the process. DNT decomposition consists of sequential hydrogen abstractions and hydroxyl attachments passing through 2,4-dinitrobenzyl alcohol, 2,4-dinitrobenzaldehyde, and 2,4-dinitrobenzoic acid. Further replacement of nitro- and carboxyl groups by hydroxyl leads to 2,4-dihydroxybenzoic acid and 2,4-dinitrophenol, respectively. Reaction intermediates and products are experimentally confirmed. Mostly of reaction steps have low energy barriers, some steps are diffusion controlled. The whole process is highly exothermic.

tri-n-butyltin hydride-mediated radical reaction of a 2-iodobenzamide: formation of an unexpected carbon-tin bond

International Nuclear Information System (INIS)

Oliveira, Marcelo T.; Alves, Rosemeire B.; Cesar, Amary; Prado, Maria Auxiliadora F.; Alves, Ricardo J.; Queiroga, Carla G.; Santos, Leonardo S.; Eberlin, Marcos N.

2007-01-01

The tri-n-butyltin hydride-mediated reaction of methyl 2,3-di-O-benzyl-4-O-trans-cinnamyl- 6-deoxy-6-(2-iodobenzoylamino)-α-D-galactopyranoside afforded an unexpected aryltributyltin compound. The structure of this new tetraorganotin(IV) product has been elucidated by 1 H, 13 C NMR spectroscopy, COSY and HMQC experiments and electrospray ionization mass spectrometry (ESI-MS). The formation of this new compound via a radical coupling reaction and a radical addition-elimination process is discussed. (author)

Electronic structure and molecular dynamics of Na2Li

Science.gov (United States)

Malcolm, Nathaniel O. J.; McDouall, Joseph J. W.

Following the first report (Mile, B., Sillman, P. D., Yacob, A. R. and Howard, J. A., 1996, J. chem. Soc. Dalton Trans , 653) of the EPR spectrum of the mixed alkali-metal trimer Na2Li a detailed study has been made of the electronic structure and structural dynamics of this species. Two isomeric forms have been found: one of the type, Na-Li-Na, of C , symmetry and another, Li-Na-Na, of C symmetry. Also, there are two linear saddle points which correspond to 'inversion' transition structures, and a saddle point of C symmetry which connects the two minima. A molecular dynamics investigation of these species shows that, at the temperature of the reported experiments (170 K), the C minimum is not 'static', but undergoes quite rapid inversion. At higher temperatures the C minimum converts to the C form, but by a mechanism very different from that suggested by minimum energy path considerations. 2 2v s s 2v 2v s

Radiolysis of carbohydrates as studied by ESR and spin-trapping—II. Glycerol- d8 xylitol, dulcitol, d-sorbitol and d-mannitol

Science.gov (United States)

Kuwabara, M.; Zhang, Z.-Y.; Inanami, O.; Yoshii, G.

Studies concerning the radicals produced in glycerol by reactions with OH radicals have been carried out by investigating deuterated glycerol (glycerol-d 8) by spin-trapping with 2-methyl-2-nitrosopropane. Free radicals produced in linear carbohydrates such as xylitol, dulcitol, D-sorbitol and D-mannitol by reactions with OH radicals as well as by direct γ-radiolysis have been also investigated by spin-trapping. The ESR spectra of the spin-trapped radicals were analysed on the basis of the results from ESR and spin-trapping experiments on glycerol and deuterated glycerol, and the formation of three radical species, CHO-CH-, CH 2-CO- and HO-CH-, due to both OH reactions and direct γ-radiolysis was confirmed for all compounds. The presence of a radical, -CO-CH-, was detected for xylitol, D-sorbitol and D-mannitol. General reactions processes induced by OH reactions or γ-radiolysis in the solid state are discussed.

Age-dependent changes in diastolic Ca{sup 2+} and Na{sup +} concentrations in dystrophic cardiomyopathy: Role of Ca{sup 2+} entry and IP{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Mijares, Alfredo [Instituto Venezolano de Investigaciones Científicas, Centro de Biofísica y Bioquímica, Caracas (Venezuela, Bolivarian Republic of); Altamirano, Francisco [Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616 (United States); Kolster, Juan [Centro de Investigaciones Biomédicas, México D.F. (Mexico); Adams, José A. [Division of Neonatology, Mount Sinai Medical Center, Miami, FL 33140 (United States); López, José R., E-mail: jrlopez@ucdavis.edu [Instituto Venezolano de Investigaciones Científicas, Centro de Biofísica y Bioquímica, Caracas (Venezuela, Bolivarian Republic of); Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616 (United States)

2014-10-03

Highlights: • Age-dependent increase in [Ca{sup 2+}]{sub d} and [Na{sup +}]{sub d} in mdx cardiomyocytes. • Gadolinium significantly reduced both [Ca{sup 2+}]{sub d} and [Na{sup +}]{sub d} at all ages. • IP{sub 3}-pathway inhibition reduced cations concentrations in dystrophic cardiomyocytes. - Abstract: Duchenne muscular dystrophy (DMD) is a lethal X-inherited disease caused by dystrophin deficiency. Besides the relatively well characterized skeletal muscle degenerative processes, DMD is also associated with a dilated cardiomyopathy that leads to progressive heart failure at the end of the second decade. The aim of the present study was to characterize the diastolic Ca{sup 2+} concentration ([Ca{sup 2+}]{sub d}) and diastolic Na{sup +} concentration ([Na{sup +}]{sub d}) abnormalities in cardiomyocytes isolated from 3-, 6-, 9-, and 12-month old mdx mice using ion-selective microelectrodes. In addition, the contributions of gadolinium (Gd{sup 3+})-sensitive Ca{sup 2+} entry and inositol triphosphate (IP{sub 3}) signaling pathways in abnormal [Ca{sup 2+}]{sub d} and [Na{sup +}]{sub d} were investigated. Our results showed an age-dependent increase in both [Ca{sup 2+}]{sub d} and [Na{sup +}]{sub d} in dystrophic cardiomyocytes compared to those isolated from age-matched wt mice. Gd{sup 3+} treatment significantly reduced both [Ca{sup 2+}]{sub d} and [Na{sup +}]{sub d} at all ages. In addition, blockade of the IP{sub 3}-pathway with either U-73122 or xestospongin C significantly reduced ion concentrations in dystrophic cardiomyocytes. Co-treatment with U-73122 and Gd{sup 3+} normalized both [Ca{sup 2+}]{sub d} and [Na{sup +}]{sub d} at all ages in dystrophic cardiomyocytes. These data showed that loss of dystrophin in mdx cardiomyocytes produced an age-dependent intracellular Ca{sup 2+} and Na{sup +} overload mediated at least in part by enhanced Ca{sup 2+} entry through Gd{sup 3+} sensitive transient receptor potential channels (TRPC), and by IP{sub 3} receptors.

Europlanet NA2 Science Networking

Science.gov (United States)

Harri, Ari-Matti; Szego, Karoly; Genzer, Maria; Schmidt, Walter; Krupp, Norbert; Lammer, Helmut; Kallio, Esa; Haukka, Harri

2013-04-01

Europlanet RI / NA2 Science Networking [1] focused on determining the major goals of current and future European planetary science, relating them to the Research Infrastructure that the Europlanet RI project [2] developed, and placing them in a more global context. NA2 also enhanced the ability of European planetary scientists to participate on the global scene with their own agenda-setting projects and ideas. The Networking Activity NA2 included five working groups, aimed at identifying key science issues and producing reference books on major science themes that will bridge the gap between the results of present and past missions and the scientific preparation of the future ones. Within the Europlanet RI project (2009-2012) the NA2 and NA2-WGs organized thematic workshops, an expert exchange program and training groups to improve the scientific impact of this Infrastructure. The principal tasks addressed by NA2 were: • Science activities in support to the optimal use of data from past and present space missions, involving the broad planetary science community beyond the "space club" • Science activities in support to the preparation of future planetary missions: Earth-based preparatory observations, laboratory studies, R&D on advanced instrumentation and exploration technologies for the future, theory and modeling etc. • Develop scientific activities, joint publications, dedicated meetings, tools and services, education activities, engaging the public and industries • Update science themes and addressing the two main scientific objectives • Prepare and support workshops of the International Space Science Institute (ISSI) in Bern and • Support Trans National Activities (TNAs), Joined Research Activities (JRAs) and the Integrated and Distributed Information Service (IDIS) of the Europlanet project These tasks were achieved by WG workshops organized by the NA2 working groups, by ISSI workshops and by an Expert Exchange Program. There were 17 official WG

Radiation-induced polymerisation of 2,3-dihydrofuran: free-radical or cationic mechanism?

International Nuclear Information System (INIS)

Janovsky, Igor; Naumov, Sergej; Knolle, Wolfgang; Mehnert, Reiner

2005-01-01

Concentrated (10 mol%) solutions of 2,3-dihydrofuran in CFCl 2 CF 2 Cl matrix were irradiated at 77 K and several intermediates (dimer radical cation, dihydrofuryl radical, and polymer radicals) were observed by low-temperature EPR spectroscopy. The irradiated solutions yielded after melting a polymeric product, which was characterised by IR spectroscopy and gel permeation chromatography. The polydisperse polymer is assumed to be formed mainly by a cationic process initiated by a dimer carbocation. The free-radical mechanism via the dihydrofuryl radical leads to low molecular weight oligomers only. Quantum chemical calculations support the interpretation of the experimental results

ZADOVOLJSTVO ZAPOSLENIH NA NAJEMNEM BENCINSKEM SERVISU PETROL D.D.

OpenAIRE

Ravnihar, Petra

2010-01-01

Namen diplomske naloge je ugotoviti zadovoljstvo zaposlenih na najemnem bencinskem servisu Šenčur. Za celovit prikaz je predstavljeno podjetje Petrol d. d. kot celota, njihova vizija za prihodnost ter delovanje posameznih franšiz, kamor spada tudi najemni servis Šenčur. Zaposleni lahko predstavljajo za podjetja konkurenčno prednost. Upravljanje človeških virov in zavedanje o potrebi po tem lahko pomeni odločilno prednost določenega podjetja. V današnjem času zgolj upravljanje organizacij n...

Photoionization of the OH radical

International Nuclear Information System (INIS)

Dehmer, P.M.

1985-01-01

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

Data of evolutionary structure change: 1A3NA-2ZLWD [Confc[Archive

Lifescience Database Archive (English)

Full Text Available 1A3NA-2ZLWD 1A3N 2ZLW A D -VLSPADKTNVKAAWGKVGAHAGEYGAEALERMFLSFPT...R VQLSGEEKAAVLALWDKVN--EEEVGGEALGRLLVVYPWTQRFFDSFGDLSNPGAVMGNPKVKAHGKKVLHSFGEGVHHLDNLKGTFAALSEL... 2ZLW D 2ZLWD WDKVN-

Predicting treatment response from dopamine D2/3 receptor bnding potential? - A study in antipsychotic-naïve patients with schizophrenia

DEFF Research Database (Denmark)

Wulff, Sanne; Pinborg, Lars Hageman; Svarer, Claus

of antipsychotic compounds on the positive symptoms. Furthermore, blockade of striatal dopamine D2 receptors have in studies shown to associate negatively with subjective well-being. Our main aim was to explore a possible predictive value of striatal dopamine D2/3 receptor binding potential (BPp) for treatment...... of 29 antipsychotic-naïve patients with schizophrenia and 26 matched healthy controls, SPECT with [123l]-IBZM was used to examine the BPP of striatal dopamine D2/3 receptors. The participants were examined at baseline and after 6 weeks of treatment with a selective D2/3 receptor antagonist, amisulpride....... Results: We found a significant inverse correlation between the striatal BPp at baseline and improvement of positive symptoms (p=0.046; R squared = 0.152) after six weeks of treatment with amisulpride. There was no association between the blockade of the D2/3 receptors and improvement of positive symptoms...

Mechanisms of radical removal by SO2

DEFF Research Database (Denmark)

Rasmussen, Christian Lund; Glarborg, Peter; Marshall, Paul

2007-01-01

It is well established from experiments in premixed, laminar flames, jet-stirred reactors, flow reactors, and batch reactors that SO2 acts to catalyze hydrogen atom removal at stoichiometric and reducing conditions. However, the commonly accepted mechanism for radical removal, SO2 + H......(+M) reversible arrow HOSO(+M), HOSO + H/OH reversible arrow SO2 + H-2/H2O, has been challenged by recent theoretical and experimental results. Based on ab initio calculations for key reactions, we update the kinetic model for this chemistry and re-examine the mechanism of fuel/SO2 interactions. We find...... that the interaction of SO, with the radical pool is more complex than previously assumed, involving HOSO and SO, as well as, at high temperatures also HSO, SH, and S. The revised mechanism with a high rate constant for H + SO2 recombination and with SO + H2O, rather than SO2 + H-2, as major products of the HOSO + H...

Permeabilization of fungal hyphae by the plant defensin NaD1 occurs through a cell wall-dependent process.

Science.gov (United States)

van der Weerden, Nicole L; Hancock, Robert E W; Anderson, Marilyn A

2010-11-26

The antifungal activity of the plant defensin NaD1 involves specific interaction with the fungal cell wall, followed by permeabilization of the plasma membrane and entry of NaD1 into the cytoplasm. Prior to this study, the role of membrane permeabilization in the activity of NaD1, as well as the relevance of cell wall binding, had not been investigated. To address this, the permeabilization of Fusarium oxysporum f. sp. vasinfectum hyphae by NaD1 was investigated and compared with that by other antimicrobial peptides, including the cecropin-melittin hybrid peptide CP-29, the bovine peptide BMAP-28, and the human peptide LL-37, which are believed to act largely through membrane disruption. NaD1 appeared to permeabilize cells via a novel mechanism that required the presence of the fungal cell wall. NaD1 and Bac2A, a linear variant of the bovine peptide bactenecin, were able to enter the cytoplasm of treated hyphae, indicating that cell death is accelerated by interaction with intracellular targets.

Phase formation in the systems ZrO2-H2SO4-Na2SO4 (NaCl)-H2O

International Nuclear Information System (INIS)

Sozinova, Yu.P.; Motov, D.L.; Rys'kina, M.P.

1988-01-01

Formation of solid phases in the systems ZrO 2 - H 2 SO 4 - Na 2 SO 4 (NaCl) - H 2 O at 25 and 75 deg C is studied. Three basic Na 2 Zr(OH) 2 (SO 4 ) 2 x (0.2 - 0.4)H 2 O, NaZrOH(SO 4 ) 2 x H 2 O, NaZrO 0.5 (OH) 2 SO 4 x 2H 2 O and three normal sodium sulfatozirconates Na 2 Zr(SO 4 ) 3 x 3H 2 O, Na 4 Zr(SO 4 ) 4 x 3H 2 O, Na 6 Zr(SO 4 ) 5 x 4H 2 O have been isolated, their solubility and crystal optical properties are determined

ESR-ENDOR study of x-irradiated single crystals of α.D.glucopyranose and α-methyl.D.glucopyranoside; environmental effects upon radiation and free radical chemistry in carbohydrate model systems

International Nuclear Information System (INIS)

Madden, K.P.

1980-01-01

Single crystals of x-irradiated α-D-glucopyranose (αGlu) and α-methyl-D-glucopyranoside (αMeGlu) were studied using electron spin resonance and electron nuclear double resonance spectroscopy, to determine products and reaction mechanisms in carbohydrate radiation and free-radical chemistry. Four free-radical products were identified in αMeGlu single crystals irradiated and studied at 77K. Irradiation and observation at 12K produced yet another species. Four free radicals were identified in αGlu single crystals irradiated and observed at 12K and 77K. Free radical reaction in αGlu and αMeGlu were induced by slowly warming crystals irradiated at 77K until conversion occurred. Environmental influences upon these free-radical reaction mechanisms are discussed. The results from previous work on irradiated aqueous glasses of αGlu is briefly reviewed, and compared to those obtained from the single crystal system

Electron spin relaxation governed by Raman processes both for Cu2+ ions and carbonate radicals in KHCO3 crystals: EPR and electron spin echo studies

Science.gov (United States)

Hoffmann, Stanislaw K.; Goslar, Janina; Lijewski, Stefan

2012-08-01

EPR studies of Cu2+ and two free radicals formed by γ-radiation were performed for KHCO3 single crystal at room temperature. From the rotational EPR results we concluded that Cu2+ is chelated by two carbonate molecules in a square planar configuration with spin-Hamiltonian parameters g|| = 2.2349 and A|| = 18.2 mT. Free radicals were identified as neutral HOCOrad with unpaired electron localized on the carbon atom and a radical anion CO3·- with unpaired electron localized on two oxygen atoms. The hyperfine splitting of the EPR lines by an interaction with a single hydrogen atom of HOCOrad was observed with isotropic coupling constants ao = 0.31 mT. Two differently oriented radical sites were identified in the crystal unit cell. Electron spin-lattice relaxation measured by electron spin echo methods shows that both Cu2+ and free radicals relax via two-phonon Raman processes with almost the same relaxation rate. The temperature dependence of the relaxation rate 1/T1 is well described with the effective Debye temperature ΘD = 175 K obtained from a fit to the Debye-type phonon spectrum. We calculated a more realistic Debye temperature value from available elastic constant values of the crystal as ΘD = 246 K. This ΘD-value and the Debye phonon spectrum approximation give a much worse fit to the experimental results. Possible contributions from a local mode or an optical mode are considered and it is suggested that the real phonon spectrum should be used for the relaxation data interpretation. It is unusual that free radicals in KHCO3 relax similarly to the well localized Cu2+ ions, which suggests a small destruction of the host crystal lattice by the ionizing irradiation allowing well coupling between radical and lattice dynamics.

Site-Specific Rate Constant Measurements for Primary and Secondary H- and D-Abstraction by OH Radicals: Propane and n -Butane

KAUST Repository

Badra, Jihad; Nasir, Ehson F.; Farooq, Aamir

2014-01-01

Site-specific rate constants for hydrogen (H) and deuterium (D) abstraction by hydroxyl (OH) radicals were determined experimentally by monitoring the reaction of OH with two normal and six deuterated alkanes. The studied alkanes include propane (C3H8), propane 2,2 D2 (CH 3CD2CH3), propane 1,1,1-3,3,3 D6 (CD 3CH2CD3), propane D8 (C3D 8), n-butane (n-C4H10), butane 2,2-3,3 D4 (CH3CD2CD2CH3), butane 1,1,1-4,4,4 D6 (CD3CH2CH2CD3), and butane D10 (C4D10). Rate constant measurements were carried out over 840-1470 K and 1.2-2.1 atm using a shock tube and OH laser absorption. Previous low-temperature data were combined with the current high-temperature measurements to generate three-parameter fits which were then used to determine the site-specific rate constants. Two primary (P1,H and P 1,D) and four secondary (S00,H, S00,D, S 01,H, and S01,D) H- and D-abstraction rate constants, in which the subscripts refer to the number of C atoms connected to the next-nearest-neighbor C atom, are obtained. The modified Arrhenius expressions for the six site-specific abstractions by OH radicals are P1,H = 1.90 × 10-18T2.00 exp(-340.87 K/T) cm 3molecule-1s-1 (210-1294 K); P1,D= 2.72 × 10-17 T1.60 exp(-895.57 K/T) cm 3molecule-1s-1 (295-1317 K); S00,H = 4.40 × 10-18 T1.93 exp(121.50 K/T) cm 3molecule-1s-1 (210-1294 K); S00,D = 1.45 × 10-20 T2.69 exp(282.36 K/T) cm 3molecule-1s-1 (295-1341 K); S01,H = 4.65 × 10-17 T1.60 exp(-236.98 K/T) cm 3molecule-1s-1 (235-1407 K); S01,D = 1.26 × 10-18 T2.07 exp(-77.00 K/T) cm 3molecule-1s-1 (294-1412 K). © 2014 American Chemical Society.

Site-Specific Rate Constant Measurements for Primary and Secondary H- and D-Abstraction by OH Radicals: Propane and n -Butane

KAUST Repository

Badra, Jihad

2014-07-03

Site-specific rate constants for hydrogen (H) and deuterium (D) abstraction by hydroxyl (OH) radicals were determined experimentally by monitoring the reaction of OH with two normal and six deuterated alkanes. The studied alkanes include propane (C3H8), propane 2,2 D2 (CH 3CD2CH3), propane 1,1,1-3,3,3 D6 (CD 3CH2CD3), propane D8 (C3D 8), n-butane (n-C4H10), butane 2,2-3,3 D4 (CH3CD2CD2CH3), butane 1,1,1-4,4,4 D6 (CD3CH2CH2CD3), and butane D10 (C4D10). Rate constant measurements were carried out over 840-1470 K and 1.2-2.1 atm using a shock tube and OH laser absorption. Previous low-temperature data were combined with the current high-temperature measurements to generate three-parameter fits which were then used to determine the site-specific rate constants. Two primary (P1,H and P 1,D) and four secondary (S00,H, S00,D, S 01,H, and S01,D) H- and D-abstraction rate constants, in which the subscripts refer to the number of C atoms connected to the next-nearest-neighbor C atom, are obtained. The modified Arrhenius expressions for the six site-specific abstractions by OH radicals are P1,H = 1.90 × 10-18T2.00 exp(-340.87 K/T) cm 3molecule-1s-1 (210-1294 K); P1,D= 2.72 × 10-17 T1.60 exp(-895.57 K/T) cm 3molecule-1s-1 (295-1317 K); S00,H = 4.40 × 10-18 T1.93 exp(121.50 K/T) cm 3molecule-1s-1 (210-1294 K); S00,D = 1.45 × 10-20 T2.69 exp(282.36 K/T) cm 3molecule-1s-1 (295-1341 K); S01,H = 4.65 × 10-17 T1.60 exp(-236.98 K/T) cm 3molecule-1s-1 (235-1407 K); S01,D = 1.26 × 10-18 T2.07 exp(-77.00 K/T) cm 3molecule-1s-1 (294-1412 K). © 2014 American Chemical Society.

Synthesis and visible-light-driven photocatalytic activity of p-n heterojunction Ag2O/NaTaO3 nanocubes

Science.gov (United States)

Yang, Songbo; Xu, Dongbo; Chen, Biyi; Luo, Bifu; Yan, Xu; Xiao, Lisong; Shi, Weidong

2016-10-01

The constructing of p-n heterojunction photocatalytic system has received much attention in environmental purification and hydrogen generation from water. In this study, an efficient visible-light-driven p-n heterojunction Ag2O/NaTaO3 was successfully prepared by chemical precipitation method at room temperature. It showed an enhanced photocatalytic activity for the degradation of rhodamine B (RhB) under visible-light irradiation, much higher than those of either individual Ag2O or NaTaO3. The reactive species scavenger results indicated the superoxide anion radicals (rad O2-) played key roles in RhB decoloration. From the experimental results and the relative band gap position of these semiconductors, a detailed possible photocatalytic mechanism of the Ag2O/NaTaO3 heterojunction under visible light was proposed. The enhancement of the photocatalytic activity was attributed to the interfacial electronic interaction between NaTaO3 and Ag2O and the high migration efficiency of photogenerated carriers.

A prototype hybrid 7π quinone-fused 1,3,2-dithiazolyl radical.

Science.gov (United States)

Decken, A; Mailman, A; Passmore, J; Rautiainen, J M; Scherer, W; Scheidt, E-W

2011-01-28

Reaction of 1,4-naphthoquinone and SNSMF(6) (M = As, Sb) in SO(2) solution in a 1 : 2 molar ratio led to the naphthoquinone fused 1,3,2-dithiazolylium salts, 3MF(6) quantitatively by multinuclear NMR (87% isolated yield of 3SbF(6)) via the cycloaddition and oxidative dehydrogenation chemistry of SNS(+) with formation of NH(4)SbF(6) and S(8). The product 3SbF(6) was fully characterized by IR, Raman, multinuclear {(1)H, (13)C, (14)N} NMR, elemental analysis, cyclic voltammetry and single crystal X-ray crystallography. The reduction of 3SbF(6) with ferrocene (Cp(2)Fe) in refluxing acetonitrile (CH(3)CN) led to the first isolation of a fused quinone-thiazyl radical, 3˙ in 73% yield. The prototype hybrid quinone-thiazyl radical 3˙ was fully characterized by IR, Raman microscopy, EI-MS, elemental analysis, solution and solid state EPR, magnetic susceptibility (2-370 K) and was found to form π*-π* dimers in the solid state as determined by single crystal X-ray crystallography. Furthermore, the thermal decomposition of 3˙ led to a novel quinone-fused 1,2,3,4-tetrathiine, 10 (x = 2) and the known 1,2,5-thiadiazole, 11. The energetics of the cycloadditon and oxidative dehydrogenation chemistry of SNS(+) and 1,4-naphthoquinone leading to 3SbF(6) were estimated in the gas phase and SO(2) solution by DFT calculations (PBE0/6-311G(d)) and lattice enthalpies obtained by the volume based thermodynamic (VBT) approach in the solid state. The gas phase ion energetics (ionization potential (IP) and electron affinity (EA)) of 3˙ are compared to related 1,3,2- and 1,2,3-dithiazolyl radicals.

Rate Constant of the Reaction between CH3O2 Radicals and OH Radicals Revisited.

Science.gov (United States)

Assaf, Emmanuel; Song, Bo; Tomas, Alexandre; Schoemaecker, Coralie; Fittschen, Christa

2016-11-17

The reaction between CH 3 O 2 and OH radicals has been studied in a laser photolysis cell using the reaction of F atoms with CH 4 and H 2 O for the simultaneous generation of both radicals, with F atoms generated through 248 nm photolysis of XeF 2 . An experimental setup combining cw-Cavity Ring Down Spectroscopy (cw-CRDS) and high repetition rate laser-induced fluorescence (LIF) to a laser photolysis cell has been used. The absolute concentration of CH 3 O 2 was measured by cw-CRDS, while the relative concentration of OH(v = 0) radicals was determined by LIF. To remove dubiety from the quantification of CH 3 O 2 by cw-CRDS in the near-infrared, its absorption cross section has been determined at 7489.16 cm -1 using two different methods. A rate constant of k 1 = (1.60 ± 0.4) × 10 -10 cm 3 s -1 has been determined at 295 K, nearly a factor of 2 lower than an earlier determination from our group ((2.8 ± 1.4) × 10 -10 cm 3 s -1 ) using CH 3 I photolysis as a precursor. Quenching of electronically excited I atoms (from CH 3 I photolysis) in collision with OH(v = 0) is suspected to be responsible for a bias in the earlier, fast rate constant.

High-level theoretical characterization of the vinoxy radical (•CH2CHO) + O2 reaction

Science.gov (United States)

Weidman, Jared D.; Allen, Ryan T.; Moore, Kevin B.; Schaefer, Henry F.

2018-05-01

Numerous processes in atmospheric and combustion chemistry produce the vinoxy radical (•CH2CHO). To understand the fate of this radical and to provide reliable energies needed for kinetic modeling of such processes, we have examined its reaction with O2 using highly reliable theoretical methods. Utilizing the focal point approach, the energetics of this reaction and subsequent reactions were obtained using coupled-cluster theory with single, double, and perturbative triple excitations [CCSD(T)] extrapolated to the complete basis set limit. These extrapolated energies were appended with several corrections including a treatment of full triples and connected quadruple excitations, i.e., CCSDT(Q). In addition, this study models the initial vinoxy radical + O2 reaction for the first time with multireference methods. We predict a barrier for this reaction of approximately 0.4 kcal mol-1. This result agrees with experimental findings but is in disagreement with previous theoretical studies. The vinoxy radical + O2 reaction produces a 2-oxoethylperoxy radical which can undergo a number of unimolecular reactions. Abstraction of a β-hydrogen (a 1,4-hydrogen shift) and dissociation back to reactants are predicted to be competitive to each other due to their similar barriers of 21.2 and 22.3 kcal mol-1, respectively. The minimum-energy β-hydrogen abstraction pathway produces a hydroperoxy radical (QOOH) that eventually decomposes to formaldehyde, CO, and •OH. Two other unimolecular reactions of the peroxy radical are α-hydrogen abstraction (38.7 kcal mol-1 barrier) and HO2• elimination (43.5 kcal mol-1 barrier). These pathways lead to glyoxal + •OH and ketene + HO2• formation, respectively, but they are expected to be uncompetitive due to their high barriers.

Solubility of NaNd(CO3)2.6H2O(c) in concentrated Na2CO3 and NaHCO3 solutions

International Nuclear Information System (INIS)

Rao, L.; Rai, D.; Felmy, A.R.; Fulton, R.W.; Novak, C.F.

1996-01-01

NaNd(CO 3 ) 2 x 6 H 2 O(c) was identified to be the final equilibrium solid phase in suspensions containing concentrated sodium carbonate (0.1 to 2.0 M) and sodium bicarbonate (0.1 to 1.0 M), with either NaNd(CO 3 ) 2 x 6 H 2 O(c) or Nd 2 (CO 3 ) 3 x xH 2 O(s) as initial solids. A thermodynamic model, based on Pitzer's specific into-interaction approach, was developed to interpret the solubility of NaNd(CO 3 ) 2 x 6 H 2 O(c) as functions of sodium carbonate and sodium bicarbonate concentrations. In this model, the solubility data of NaNd(CO 3 ) 2 x 6 H 2 O(c) were explained by assuming the formation of NdCO 3 + , Nd(CO 3 ) 2 - and Nd(CO 3 ) 3 3- species and invoking the specific ion interactions between Na + and Nd(CO 3 ) 3 3- . Ion interaction parameters for Na + -Nd(CO 3 ) 3 3- were developed to fit the solubility data. Based on the model calculations, Nd(CO 3 ) 3 3- was the predominant aqueous neodymium species in 0.1 to 2 M sodium carbonate and 0.1 to 1 M sodium bicarbonate solutions. The logarithm of the NaNd(CO 3 ) 2 x 6 H 2 O solubility product (NaNd(CO 3 ) 2 x 6 H 2 O(c)=Na + +Nd 3+ +2 CO 3 2- +6 H 2 O) was calculated to be -21.39. This model also provided satisfactory interpretation of the solubility data of the analogous Am(III) system in less concentrated carbonate and bicarbonate solutions. (orig.)

Detection methods for atoms and radicals in the gas phase

Science.gov (United States)

Hack, W.

This report lists atoms and free radicals in the gas phase which are of interest for environmental and flame chemistry and have been detected directly. The detection methods which have been used are discussed with respect to their range of application, specificity and sensitivity. In table 1, detection methods for the five atoms of group IV (C, Si, Ge, Sn, Pb) and about 60 radicals containing at least one atom of group IV are summarized (CH, Cd, Cf, CC1, CBr, Cn, Cs, CSe, CH2, CD2, Chf, Cdf, CHC1, CHBr, CF2, CC12, CBr2, CFC1, CFBr, CH3, CD3, CF3, CH2F, CH2C1, CH2Br, CHF2, CHC12, CHBr2, Hco, Fco, CH30, CD30, CH2OH, CH3S, Nco, CH4N, CH302, CF302; C2, C2N, C2H, C20, C2HO, C2H3, C2F3, C2H5, C2HsO, C2H4OH, CH3CO, CD3CO, C2H3O, C2H502, CH3COO2, C2H4N, C2H6N, C3; Si, SiF, SiF2, SiO, SiC, Si2; Ge, GeC, GeO, GeF, GeF2, GeCl2, Sn, SnF, SnO, SnF2, Pb, PbF, PbF2, PbO, PbS). In table 2 detection methods for about 25 other atoms and 60 radicals are listed: (H, D, O, O2, Oh, Od, HO2, DO2, F, Ci, Br, I, Fo, Cio, BrO, Io, FO2, C1O2, Li, Na, K, Rb, Cs, N, N3, Nh, Nd, Nf, Nci, NBr, NH2, ND2, Nhd, Nhf, NF2, NC12, N2H3, No, NO2, NO3, Hno, Dno, P, Ph, Pd, Pf, Pci, PH2, PD2, PF2, Po, As, AsO, AsS, Sb, Bi, S, S2, Sh, Sd, Sf, SF2, So, Hso, Dso, Sn, Se, Te, Se2, SeH, SeD, SeF, SeO, SeS, SeN, TeH, TeO, Bh, BH2, Bo, Bn, B02, Cd, Hg, UF5). The tables also cite some recent kinetic applications of the various methods.

Conception et calibration d'un sonoreacteur pour l'oxydation de la cellulose par le systeme TEMPO/NaOCl/NaBr

Science.gov (United States)

Paquin, Michel

Avec le contexte economique actuel dans le domaine des pates et papiers au Canada, l'industrie se doit de diversifier ses produits mis en marche. La fermeture de plus de 20 usines depuis 2005, une baisse du PIB de l'industrie de 1,4 milliard CAD entre 1999--2008, une baisse de la demande de 2,4 %, une diminution du prix de la pate de 20,9 % depuis juillet 2009. La delocalisation du secteur vers l'Asie et l'hemisphere sud sont autant de raisons pour laquelle l'industrie se doit d'etre a l'avant plan de nouvelle technologie a base de fibre de bois. Pour augmenter leur rentabilite, l'industrie se doit de diversifier ses produits dans d'autres secteurs que le simple fabricant de papier impression-ecriture. Sa diversification passe par l'elaboration de nouveaux papiers a valeur ajoutee (papier conducteur, papier bioactif, etc.), par l'utilisation de la biomasse forestiere pour la production d'energie, par l'utilisation de la biomasse forestiere pour l'elaboration d'une plateforme de chimie verte, par l'utilisation de la lignine pour le developpement de polymeres et par l'utilisation de la fibre cellulosique pour la fabrication de nanomateriaux. La fabrication de nanofibrille de cellulose peut devenir un des produits qui servira a diversifier la production des usines de pates et papiers. Les nanofibrilles de cellulose possedent des proprietes mecaniques et chimiques exceptionnelles. Les nanofibrilles de cellulose sont fabriquees a partir d'une oxydation selective de la pate kraft de feuillu avec le systeme TEMPO-NaOCl-NaBr. L'oxydation selective de l'alcool primaire en C6 du monomere de glucose sous forme de carboxylates engendre une modification chimique de la cellulose qui accroit l'hydrophilicite des fibrilles. Suite a cette oxydation, nous devons effectuer une desintegration mecanique de la fibre kraft de feuillu oxydee pour separer les fibrilles. Le processus d'oxydation de la fibre par le systeme TEMPO-NaOCl-NaBr et sa defibrillation par la suite engendre une

Ultraviolet photodissociation dynamics of the benzyl radical.

Science.gov (United States)

Song, Yu; Zheng, Xianfeng; Lucas, Michael; Zhang, Jingsong

2011-05-14

Ultraviolet (UV) photodissociation dynamics of jet-cooled benzyl radical via the 4(2)B(2) electronically excited state is studied in the photolysis wavelength region of 228 to 270 nm using high-n Rydberg atom time-of-flight (HRTOF) and resonance enhanced multiphoton ionization (REMPI) techniques. In this wavelength region, H-atom photofragment yield (PFY) spectra are obtained using ethylbenzene and benzyl chloride as the precursors of benzyl radical, and they have a broad peak centered around 254 nm and are in a good agreement with the previous UV absorption spectra of benzyl. The H + C(7)H(6) product translational energy distributions, P(E(T))s, are derived from the H-atom TOF spectra. The P(E(T)) distributions peak near 5.5 kcal mol(-1), and the fraction of average translational energy in the total excess energy, , is ∼0.3. The P(E(T))s indicate the production of fulvenallene + H, which was suggested by recent theoretical studies. The H-atom product angular distribution is isotropic, with the anisotropy parameter β ≈ 0. The H/D product ratios from isotope labeling studies using C(6)H(5)CD(2) and C(6)D(5)CH(2) are reasonably close to the statistical H/D ratios, suggesting that the H/D atoms are scrambled in the photodissociation of benzyl. The dissociation mechanism is consistent with internal conversion of the electronically excited benzyl followed by unimolecular decomposition of the hot benzyl radical on the ground state.

Oxidative generation of guanine radicals by carbonate radicals and their reactions with nitrogen dioxide to form site specific 5-guanidino-4-nitroimidazole lesions in oligodeoxynucleotides.

Science.gov (United States)

Joffe, Avrum; Mock, Steven; Yun, Byeong Hwa; Kolbanovskiy, Alexander; Geacintov, Nicholas E; Shafirovich, Vladimir

2003-08-01

A simple photochemical approach is described for synthesizing site specific, stable 5-guanidino-4-nitroimidazole (NIm) adducts in single- and double-stranded oligodeoxynucleotides containing single and multiple guanine residues. The DNA sequences employed, 5'-d(ACC CG(1)C G(2)TC CG(3)C G(4)CC) and 5'-d(ACC CG(1)C G(2)TC C), were a portion of exon 5 of the p53 tumor suppressor gene, including the codons 157 (G(2)) and 158 (G(3)) mutation hot spots in the former sequence with four Gs and the codon 157 (G(2)) mutation hot spot in the latter sequence with two Gs. The nitration of oligodeoxynucleotides was initiated by the selective photodissociation of persulfate anions to sulfate radicals induced by UV laser pulses (308 nm). In aqueous solutions, of bicarbonate and nitrite anions, the sulfate radicals generate carbonate anion radicals and nitrogen dioxide radicals by one electron oxidation of the respective anions. The guanine residue in the oligodeoxynucleotide is oxidized by the carbonate anion radical to form the neutral guanine radical. While the nitrogen dioxide radicals do not react with any of the intact DNA bases, they readily combine with the guanine radicals at either the C8 or the C5 positions. The C8 addition generates the well-known 8-nitroguanine (8-nitro-G) lesions, whereas the C5 attack produces unstable adducts, which rapidly decompose to NIm lesions. The maximum yields of the nitro products (NIm + 8-nitro-G) were typically in the range of 20-40%, depending on the number of guanine residues in the sequence. The ratio of the NIm to 8-nitro-G lesions gradually decreases from 3.4 in the model compound, 2',3',5'-tri-O-acetylguanosine, to 2.1-2.6 in the single-stranded oligodeoxynucleotides and to 0.8-1.1 in the duplexes. The adduct of the 5'-d(ACC CG(1)C G(2)TC C) oligodeoxynucleotide containing the NIm lesion in codon 157 (G(2)) was isolated in HPLC-pure form. The integrity of this adduct was established by a detailed analysis of exonuclease digestion

The system NaVO3-Na2WO4-Na2W2O7

International Nuclear Information System (INIS)

Kazanbekov, V.R.; Gasanaliev, A.M.; Kazanbekov, R.G.

1994-01-01

Phase diagrams of sodium metavanadate-sodium ditungstate, sodium metavanadate-sodium tungstate systems and surface of primary crystallization of sodium metavabadate-sodium tungstate-sodium ditungstate system were studied. The system sodium metavanadate-sodium ditungstate is eutectic one. Compound NaVO 3 x2Na 2 WO 4 is formed in solid state in sodium metavanadate-sodium tungstate system. Liquidus surface of sodium metavanadate-sodium tungstate-sodium ditungstate is presented by three crystallization fields of initial components. Composition and melting point of ternary eutectics are determined

Radical-mediated reduction of the dithiocarbamate group under tin-free conditions.

Science.gov (United States)

McMaster, Claire; Bream, Robert N; Grainger, Richard S

2012-06-28

Reductive desulfurisation of dithiocarbamates is conveniently achieved using H(3)PO(2)-Et(3)N-ACCN in refluxing dioxane. Fused and spirocyclic β-lactams, prepared through 4-exo trig carbamoyl radical cyclisation-dithiocarbamate group transfer reactions, are reduced without fragmentation of the strained 4-membered ring. Diethyl tetraacetyl-d-glucopyranosyl dithiocarbamate is selectively reduced with or without acyloxy group migration depending on reaction conditions and choice of reductant. Deuterium incorporation from D(3)PO(2)-Et(3)N is observed for a system involving a nucleophilic radical intermediate, but not in the case of the electrophilic radical obtained through acyloxy group migration on a glucose derivative.

3D 23Na MRI of human skeletal muscle at 7 Tesla: initial experience

International Nuclear Information System (INIS)

Chang, Gregory; Wang, Ligong; Regatte, Ravinder R.; Schweitzer, Mark E.

2010-01-01

To evaluate healthy skeletal muscle pre- and post-exercise via 7 T 23 Na MRI and muscle proton T 2 mapping, and to evaluate diabetic muscle pre- and post-exercise via 7 T 23 Na MRI. The calves of seven healthy subjects underwent imaging pre- and post-exercise via 7 T 23 Na MRI (3D fast low angle shot, TR/TE = 80 ms/0.160 ms, 4 mm x 4 mm x 4 mm) and 1 week later by 1 H MRI (multiple spin-echo sequence, TR/TE = 3,000 ms/15-90 ms). Four type 2 diabetics also participated in the 23 Na MRI protocol. Pre- and post-exercise sodium signal intensity (SI) and proton T 2 relaxation values were measured/calculated for soleus (S), gastrocnemius (G), and a control, tibialis anterior (TA). Two-tailed t tests were performed. In S/G in healthy subjects post-exercise, sodium SI increased 8-13% (p 1/2 = 22 min), and 1 H T 2 values increased 12-17% (p 1/2 = 12-15 min). In TA, no significant changes in sodium SI or 1 H T 2 values were seen (-2.4 to 1%, p > 0.17). In S/G in diabetics, sodium SI increased 10-11% (p 1/2 = 27-37 min) without significant change in the TA SI (-3.6%, p = 0.066). It is feasible to evaluate skeletal muscle via 3D 23 Na MRI at 7 T. Post-exercise muscle 1 H T 2 values return to baseline more rapidly than sodium SI. Diabetics may demonstrate delayed muscle sodium SI recovery compared with healthy subjects. (orig.)

Crystallization behavior of Li2O-SiO2, Na2O-SiO2 and Na2O-CaO-SiO2 glasses; Li2O-SiO2, Na2O-SiO2, Na2O-CaO-SiO2 kei glass no kessho sekishutsu kyodo

Energy Technology Data Exchange (ETDEWEB)

Tsutsumi, K.; Otake, J.; Nagasaka, T.; Hino, M. [Tohoku University, Sendai (Japan)

1998-06-01

It has been known that crystallization of mold powder is effective on the disturbance of heat transfer between mold and solidified shell in production of middle carbon steel slabs in continuous casting process. But it has not yet been made clear which composition of mold powder is the most suitable for crystallization. The crystallization behavior of Li2O-SiO2, Na2O-SiO2 and Na2O-CaO-SiO2 glasses was observed by differential thermal analysis (DTA) and hot-thermocouple methods with DTA in the present work. As a result, addition of alkaline metal and alkaline earth metal oxides to SiO2 increased the critical cooling rate for glass formation in binary system of Li2O-SiO2 and Na2O-SiO2 and Li2O-SiO2 system crystallized easier than Na2O-SiO2 system. In ternary system of Na2O-CaO-SiO2, addition of Na2O hurried the critical cooling rate at CaO/SiO2=0.93 mass ratio, but the rate was almost constant in the composition range of more than 15 mass% Na2O. The slag of CaO/SiO2=0.93 made the rate faster than the slag of CaO/SiO2=0.47 at constant content of 10mass% Na2O. 17 refs., 10 figs., 3 tabs.

GC-MS analysis of ethanol solution with D2O as solvent implanted by low energy N+

International Nuclear Information System (INIS)

Shi Huaibin; Shao Chunlin; Yu Zengliang

2001-10-01

Low energy ions were produced by N 2 glow-discharge. The positive ones were accelerated into ethanol solution with D 2 O as solvent to induce chemical reactions. GC-MS analysis showed that DCH 2 CH 2 OH, HOCH 2 CH 2 OD were produced by such kind of implantation. Thus, it was proved that the reaction was mainly caused by radicals generated by decomposition of water molecules, D . and . OD played an important role in the process. Meanwhile, CH 3 COOD and HOCH 2 CH 2 ND 2 were also found in the products, so it was concluded that the reaction was carried out under an oxidative atmosphere, which was thought to be probably related to . OD radicals, too. The capture of D from D 2 O by N + to form . ND 2 radicals was not only an initial step to produce HOCH 2 CH 2 ND 2 but also served as a probable pattern for 'nitrogen deposition'. All these were helpful to reveal the mechanism of the reaction induced by low energy N + implanting into solution samples

An experimental investigation into power broadening of the Na-D lines in a flame

International Nuclear Information System (INIS)

Calcar, R.A. van.

1980-01-01

Investigations are described aimed at the verification of the existence of power broadening in fluorescence, as predicted by theory in the case of a broadband excitation source. Measurements were performed on a vapour of sodium (Na) atoms in a pre-mixed H 2 -O 2 -Ar flame under 1 atm pressure. The easily excited first resonance (or D) lines of Na were chosen for the observation of power broadening in fluorescence. (Auth.)

OH, HO2, and HO2* Radical Chemistry During PROPHET-AMOS 2016: Measurements and Model Comparison

Science.gov (United States)

Bottorff, B.; Lew, M.; Rickly, P.; Stevens, P. S.

2017-12-01

The hydroxyl (OH) and peroxy radicals, both the hydroperoxy radical (HO2) and organic peroxy radicals (RO2), play an important role in atmospheric chemistry. In addition to controlling lifetimes of many trace gases important to issues of global climate change, reactions of these radicals can also lead to the production of ozone and secondary organic aerosols in the atmosphere. Previous measurements of these radicals in remote forest environments have shown serious discrepancies with modeled concentrations. These results bring into question our understanding of the atmospheric chemistry of isoprene and other biogenic VOCs under low NOX conditions. In the summer of 2016, OH, HO2 and HO2* (HO2 + αRO2) radicals were measured using the Indiana University Laser-Induced Fluorescence Fluorescence Assay by Gas Expansion (LIF-FAGE) technique as part of the Program for Research on Oxidants: PHtochemistry, Emissions, and Transport- Atmospheric Measurements of Oxidants in Summer (PROPHET-AMOS). This campaign took place in a forested area in northern Michigan characterized by high mixing ratios of isoprene and low mixing ratios of NOX. Ambient measurements from this campaign will be compared to previous measurements at this site and to modeled predictions using both the Regional Atmospheric Chemistry Mechanism (RACM2) and the Master Chemical Mechanism. Potential interferences associated with the OH measurements will also be examined.

Titration of poly(dA-dT) . poly(dA-dT) in solution at variable NaCl concentration.

Science.gov (United States)

Airoldi, Marta; Boicelli, C Andrea; Cadoni, Fabio; Gennaro, Giuseppe; Giomini, Marcello; Giuliani, Anna M; Giustini, Mauro

2004-10-05

CD and uv absorption data showed that high molecular weight poly(dA-dT) . poly(dA-dT), at 298 K, undergoes an acid-induced transition from B-double helix to random coil in NaCl solutions of different concentrations, ranging from 0.005 to 0.600M. Similarly, titration of the polynucleotide with a strong base causes duplex-to-single strands transition. The base- and acid-induced transitions were both reversible by back-titration (with an acid or, respectively, with a base): the apparent pKa were the same in both directions. However, the number of protons per titratable site (adenine N1) required to reach half-denaturation was in great excess over the stoichiometric value; to a much larger extent, the same effect was observed also for the deprotonation of the N3H sites of thymine. Moreover, in the basic denaturation experiments, at low salt concentrations ([NaCl]acid than calculated was needed to back-titrate the base excess to half-denaturation. Both effects could be qualitatively justified on the basis of the counterion condensation theory of polyelectrolytes and considering the energy barrier created by the negatively charged phosphodiester groups to the penetration of the OH- ions inside the double helix and the screening effect of the Na+ ions on such charges, in the deprotonation experiments.

Free radical inactivation of trypsin

International Nuclear Information System (INIS)

Cudina, Ivana; Jovanovic, S.V.

1988-01-01

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

Atmospheric chemistry of CF3O radicals: Reaction with H2O

DEFF Research Database (Denmark)

Wallington, T.J.; Hurley, M.D.; Schneider, W.F.

1993-01-01

Evidence is presented that CF3O radicals react with H2O in the gas phase at 296 K to give CF3OH and OH radicals. This reaction is calculated to be exothermic by 1.7 kcal mol-I implying a surprisingly strong CF3O-H bond energy of 120 +/- 3 kcal mol-1. Results from a relative rate experimental study...... suggest that the rate constant for the reaction of CF3O radicals with H2O lies in the range (0.2-4.0) X 10(-17) cm3 molecule-1 s-1. Implications for the atmospheric chemistry of CF3O radicals are discussed....

Na7 [Fe2S6 ] , Na2 [FeS2 ] and Na2 [FeSe2 ] : New 'reduced' sodium chalcogenido ferrates

Science.gov (United States)

Stüble, Pirmin; Peschke, Simon; Johrendt, Dirk; Röhr, Caroline

2018-02-01

Three new 'reduced' FeII containing sodium chalcogenido ferrates were obtained applying a reductive synthetic route. The mixed-valent sulfido ferrate Na7 [Fe2S6 ] , which forms bar-shaped crystals with metallic greenish luster, was synthesized in pure phase from natural pyrite and elemental sodium at a maximum temperature of 800 °C. Its centrosymmetric triclinic structure (SG P 1 bar , a = 764.15(2), b = 1153.70(2), c = 1272.58(3) pm, α = 62.3325 (7) , β = 72.8345 (8) , γ = 84.6394 (8) ° , Z = 3, R1 = 0.0185) exhibits two crystallographically different [Fe2S6 ] 7 - dimers of edge-sharing [FeS4 ] tetrahedra, with somewhat larger Fe-S distances than in the fully oxidized FeIII dimers of e.g. Na6 [Fe2III S6 ] . In contrast to the localized AFM ordered pure di-ferrates(III), the Curie-Weiss behavior of the magnetic susceptibility proves the rarely observed valence-delocalized S = 9/2 state of the mixed-valent FeIII /FeII dimer. The nearly spin-only value of the magnetic moment combined with the chemical bonding not generally differing from that in pure ferrates(II) and (III), provides a striking argument, that the reduction of the local Fe spin moments observed in all condensed sulfido ferrate moieties is connected with the AFM spin ordering. The two isotypic ferrates(II) Na2 [FeS2 ] and Na2 [FeSe2 ] with chain-like structural units (SG Ibam, a = 643.54(8)/ 660.81(1), b = 1140.2(2)/1190.30(2) c = 562.90(6)/585.59(1) pm, Z = 4, R1 = 0.0372/0.0466) crystallize in the K2 [ZnO2 ] -type structure. Although representing merely further members of the common series of chalcogenido metallates(II) Na2 [MIIQ2 ] , these two new phases, together with Na6 [FeS4 ] and Li2 [FeS2 ] , are the only examples of pure FeII alkali chalcogenido ferrates. The new compounds allow for a general comparison of di- and chain ferrates(II) and (III) and mixed-valent analogs concerning the electronic and magnetic properties (including Heisenberg super-exchange and double-exchange interactions

Kinetics of the Reaction of CH3O2 Radicals with OH Studied over the 292-526 K Temperature Range.

Science.gov (United States)

Yan, Chao; Kocevska, Stefani; Krasnoperov, Lev N

2016-08-11

Reaction of methyl peroxy radicals with hydroxyl radicals, CH3O2 + OH → CH3O + HO2 (1a) and CH3O2 + OH → CH2OO + H2O (1b) was studied using pulsed laser photolysis coupled to transient UV-vis absorption spectroscopy over the 292-526 K temperature range and pressure 1 bar (bath gas He). Hydroxyl radicals were generated in the reaction of electronically excited oxygen atoms O((1)D), produced in the photolysis of N2O at 193.3 nm, with H2O. Methyl peroxy radicals were generated in the reaction of methyl radicals, CH3, produced in the photolysis of acetone at 193.3 nm, and subsequent reaction of CH3 with O2. Temporal profiles of OH were monitored via transient absorption of light from a DC discharge H2O/Ar low-pressure resonance lamp at ca. 308 nm. The absolute intensity of the photolysis light was determined by accurate in situ actinometry based on the ozone formation in the presence of molecular oxygen. The overall rate constant of the reaction is k1a+1b = (8.4 ± 1.7) × 10(-11)(T/298 K)(-0.81) cm(3) molecule(-1) s(-1) (292-526 K). The branching ratio of channel 1b at 298 K is less than 5%.

Intramolecular addition of benzylic radicals onto ketenimines. Synthesis of 2-alkylindoles.

Science.gov (United States)

Alajarín, Mateo; Vidal, Angel; Ortín, María-Mar

2003-12-07

The inter- and intramolecular addition of free radicals onto ketenimines is studied. All the attempts to add intermolecularly several silicon, oxygen or carbon centered radicals to N-(4-methylphenyl)-C,C-diphenyl ketenimine were unsuccessful. In contrast, the intramolecular addition of benzylic radicals, generated from xanthates, onto the central carbon of a ketenimine function with its N atom linked to the ortho position of the aromatic ring occurred under a variety of reaction conditions. These intramolecular cyclizations provide a novel radical-mediated synthesis of 2-alkylindoles.

The effect of bicarbonate on menadione-induced redox cycling and cytotoxicity: potential involvement of the carbonate radical.

Science.gov (United States)

Aljuhani, Naif; Michail, Karim; Karapetyan, Zubeida; Siraki, Arno G

2013-10-01

We have investigated the effect of NaHCO3 on menadione redox cycling and cytotoxicity. A cell-free system utilized menadione and ascorbic acid to catalyze a redox cycle, and we utilized murine hepatoma (Hepa 1c1c7) cells for in vitro experiments. Experiments were performed using low (2 mmol/L) and physiological (25 mmol/L) levels of NaHCO3 in buffer equilibrated to physiological pH. Using oximetry, ascorbic acid oxidation, and ascorbyl radical detection, we found that menadione redox cycling was enhanced by NaHCO3. Furthermore, Hepa 1c1c7 cells treated with menadione demonstrated cytotoxicity that was significantly increased with physiological concentrations of NaHCO3 in the media, compared with low levels of NaHCO3. Interestingly, the inhibition of superoxide dismutase (SOD) with 2 different metal chelators was associated with a protective effect against menadione cytotoxicity. Using isolated protein, we found a significant increase in protein carbonyls with menadione-ascorbate-SOD with physiological NaHCO3 levels; low NaHCO3 or SOD-free reactions produced lower levels of protein carbonyls. In conclusion, these findings suggest that the hydrogen peroxide generated by menadione redox cycling together with NaHCO3-CO2 are potential substrates for SOD peroxidase activity that can lead to carbonate-radical-enhanced cytotoxicity. These findings demonstrate the importance of NaHCO3 in menadione redox cycling and cytotoxicity.

Photofragment imaging study of the CH2CCH2OH radical intermediate of the OH+allene reaction

International Nuclear Information System (INIS)

Raman, Arjun S.; Justine Bell, M.; Lau, K.-C.; Butler, Laurie J.

2007-01-01

These velocity map imaging experiments characterize the photolytic generation of one of the two radical intermediates formed when OH reacts via an addition mechanism with allene. The CH 2 CCH 2 OH radical intermediate is generated photolytically from the photodissociation of 2-chloro-2-propen-1-ol at 193 nm. Detecting the Cl atoms using [2+1] resonance-enhanced multiphoton ionization evidences an isotropic angular distribution for the Cl+CH 2 CCH 2 OH photofragments, a spin-orbit branching ratio for Cl( 2 P 1/2 ):Cl( 2 P 3/2 ) of 0.28, and a bimodal recoil kinetic energy distribution. Conservation of momentum and energy allows us to determine from this data the internal energy distribution of the nascent CH 2 CCH 2 OH radical cofragment. To assess the possible subsequent decomposition pathways of this highly vibrationally excited radical intermediate, we include electronic structure calculations at the G3//B3LYP level of theory. They predict the isomerization and dissociation transition states en route from the initial CH 2 CCH 2 OH radical intermediate to the three most important product channels for the OH+allene reaction expected from this radical intermediate: formaldehyde+C 2 H 3 , H+acrolein, and ethene+CHO. We also calculate the intermediates and transition states en route from the other radical adduct, formed by addition of the OH to the center carbon of allene, to the ketene+CH 3 product channel. We compare our results to a previous theoretical study of the O+allyl reaction conducted at the CBS-QB3 level of theory, as the two reactions include several common intermediates

Single minimum incision endoscopic radical nephrectomy for renal tumors with preoperative virtual navigation using 3D-CT volume-rendering

Directory of Open Access Journals (Sweden)

Shioyama Yasukazu

2010-04-01

Full Text Available Abstract Background Single minimum incision endoscopic surgery (MIES involves the use of a flexible high-definition laparoscope to facilitate open surgery. We reviewed our method of radical nephrectomy for renal tumors, which is single MIES combined with preoperative virtual surgery employing three-dimensional CT images reconstructed by the volume rendering method (3D-CT images in order to safely and appropriately approach the renal hilar vessels. We also assessed the usefulness of 3D-CT images. Methods Radical nephrectomy was done by single MIES via the translumbar approach in 80 consecutive patients. We performed the initial 20 MIES nephrectomies without preoperative 3D-CT images and the subsequent 60 MIES nephrectomies with preoperative 3D-CT images for evaluation of the renal hilar vessels and the relation of each tumor to the surrounding structures. On the basis of the 3D information, preoperative virtual surgery was performed with a computer. Results Single MIES nephrectomy was successful in all patients. In the 60 patients who underwent 3D-CT, the number of renal arteries and veins corresponded exactly with the preoperative 3D-CT data (100% sensitivity and 100% specificity. These 60 nephrectomies were completed with a shorter operating time and smaller blood loss than the initial 20 nephrectomies. Conclusions Single MIES radical nephrectomy combined with 3D-CT and virtual surgery achieved a shorter operating time and less blood loss, possibly due to safer and easier handling of the renal hilar vessels.

Oxidation of spin-traps by chlorine dioxide (ClO2) radical in aqueous solutions: first ESR evidence of formation of new nitroxide radicals.

Science.gov (United States)

Ozawa, T; Miura, Y; Ueda, J

1996-01-01

The reactivities of the chlorine dioxide (ClO2), which is a stable free radical towards some water-soluble spin-traps were investigated in aqueous solutions by an electron spin resonance (ESR) spectroscopy. The ClO2 radical was generated from the redox reaction of Ti3+ with potassium chlorate (KClO3) in aqueous solutions. When one of the spin-traps, 5,5-dimethyl-1-pyrroline N-oxide (DMPO), was included in the Ti3+-KClO3 reaction system, ESR spectrum due to the ClO2 radical completely disappeared and a new ESR spectrum [aN(1) = 0.72 mT, aH(2) = 0.41 mT], which is different from that of DMPO-ClO2 adduct, was observed. The ESR parameters of this new ESR signal was identical to those of 5,5-dimethylpyrrolidone-(2)-oxyl-(1) (DMPOX), suggesting the radical species giving the new ESR spectrum is assignable to DMPOX. The similar ESR spectrum consisting of a triplet [aN(1) = 0.69 mT] was observed when the derivative of DMPO, 3,3,5,5-tetramethyl-1-pyrroline N-oxide (M4PO) was included in the Ti3+-KClO3 reaction system. This radical species is attributed to the oxidation product of M4PO, 3,3,5,5-tetramethylpyrrolidone-(2)-oxyl-(1) (M4POX). When another nitrone spin-trap, alpha-(4-pyridyl-1-oxide)-N-t-butylnitrone (POBN) was used as a spin-trap, the ESR signal intensity due to the ClO2 radical decreased and a new ESR signal consisting of a triplet [aN(1) = 0.76 mT] was observed. The similar ESR spectrum was observed when N-t-butyl-alpha- nitrone (PBN) was used as a spin-trap. This ESR parameter [a(N)(1) = 0.85 mT] was identical to the oxidation product of PBN, PBNX. Thus, the new ESR signal observed from POBN may be assigned to the oxidation product of POBN, POBNX. These results suggest that the ClO2, radical does not form the stable spin adducts with nitrone spin-traps, but oxidizes these spin-traps to give the corresponding nitroxyl radicals. On the other hand, nitroso spin-traps, 5,5-dibromo-4-nitrosobenzenesulfonate (DBNBS), and 2-methyl-2-nitrosopropane (MNP) did not trap

Investigating free radical generation in HepG2 cells using immuno-spin trapping.

Science.gov (United States)

Horinouchi, Yuya; Summers, Fiona A; Ehrenshaft, Marilyn; Kawazoe, Kazuyoshi; Tsuchiya, Koichiro; Tamaki, Toshiaki; Mason, Ronald P

2014-10-01

Oxidative stress can induce the generation of free radicals, which are believed to play an important role in both physiological and pathological processes and a number of diseases such as cancer. Therefore, it is important to identify chemicals which are capable of inducing oxidative stress. In this study, we evaluated the ability of four environmental chemicals, aniline, nitrosobenzene (NB), N,N-dimethylaniline (DMA) and N,N-dimethyl-4-nitrosoaniline (DMNA), to induce free radicals and cellular damage in the hepatoma cell line HepG2. Cytotoxicity was assessed using lactate dehydrogenase (LDH) assays and morphological changes were observed using phase contrast microscopy. Free radicals were detected by immuno-spin trapping (IST) in in-cell western experiments or in confocal microscopy experiments to determine the subcellular localization of free radical generation. DMNA induced free radical generation, LDH release and morphological changes in HepG2 cells whereas aniline, NB and DMA did not. Confocal microscopy showed that DMNA induced free radical generation mainly in the cytosol. Preincubation of HepG2 cells with N-acetylcysteine and 2,2'-dipyridyl significantly prevented free radical generation upon subsequent incubation with DMNA, whereas preincubation with apocynin and dimethyl sulfoxide did not. These results suggest that DMNA induces oxidative stress and that reactive oxygen species, metals and free radical generation play a critical role in DMNA-induced cytotoxicity. Copyright © 2014. Published by Elsevier Inc.

Synthesis of heterocyclic chalcone derivatives and their radical scavenging ability toward 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals

International Nuclear Information System (INIS)

Hwang, Kijun; Kim, Hoseok; Kim, Beomtae; Han, Incheol

2012-01-01

A series of heterocyclic chalcone derivatives bearing heterocycles such as thiophene or furan ring as an isostere of benzene ring were carefully prepared, and the influence of heterocycles on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities was systematically investigated. Structure-activity relationships (SAR) analysis showed that the activities of thiophene ring-containing chalcones were higher than those of furan ring containing chalcones, and the presence of methyl substituent of heterocyclic ring distinctly affected the activities compared with non-substituted heterocycles in an opposite manner, with the 4'-methyl group of thiophene ring increasing activity and the 3'-methyl group of the furan ring decreasing activity. The distinct isosteric effect of heterocycles (i.e., thiophene or furan ring) on radical scavenging activities of heterocyclic chalcones was distinctly demonstrated in our work

Methane coupling reaction in an oxy-steam stream through an OH radical pathway by using supported alkali metal catalysts

KAUST Repository

Liang, Yin

2014-03-24

A universal reaction mechanism involved in the oxidative coupling of methane (OCM) is demonstrated under oxy-steam conditions using alkali-metal-based catalysts. Rigorous kinetic measurements indicated a reaction mechanism that is consistent with OH radical formation from a H 2O-O2 reaction followed by C-H activation in CH 4 with an OH radical. Thus, the presence of water enhances both the CH4 conversion rate and the C2 selectivity. This OH radical pathway that is selective for the OCM was observed for the catalyst without Mn, which suggests clearly that Mn is not the essential component in a selective OCM catalyst. The experiments with different catalyst compositions revealed that the OH.-mediated pathway proceeded in the presence of catalysts with different alkali metals (Na, K) and different oxo anions (W, Mo). This difference in catalytic activity for OH radical generation accounts for the different OCM selectivities. As a result, a high C2 yield is achievable by using Na2WO4/SiO2, which catalyzes the OH.-mediated pathway selectively. Make it methane: A universal reaction mechanism involved in the oxidative coupling of methane is demonstrated under oxy-stream conditions by using alkali-metal-based catalysts. Rigorous kinetic measurements indicated a reaction mechanism that is consistent with OH radical formation from an H2O-O2 reaction, followed by C-H activation in CH4 with an OH radical. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The synthesis and spectroscopic study of stable free radicals related to piperidine-n-oxyl, including a stable bi-radical; Syntheses et etudes spectroscopiques de radicaux libres piperidiniques et d'un biradical stable, du type nitroxyde

Energy Technology Data Exchange (ETDEWEB)

Briere, R [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires, Laboratoire de chimie organique physique

1967-06-01

A new synthesis of di-tert-butyl nitroxide using the reaction between tert-butyl magnesium chloride and nitro-tert-butane is presented in the first section. Synthesis and investigation of stable free piperidine-N-oxyl radicals are described in the second section. All these nitroxides have been characterised by their I. R., U. V. and E. P. R. absorption spectra. The final section contains a description of the synthesis of a stable bi-radical of the nitroxide type by condensation of 2,2, 6, 6-tetramethyl-piperid-4-one-l-oxyl with hydrazine. (author) [French] La premiere partie expose une nouvelle methode de synthase du di-t-butyl nitroxyde, par action d'halogenures de t-butyl magnesium sur le nitro-t-butane (Rdt maximum 45 pour cert, purete 86 pour cent). Une etude de radicaux. libres stables pipericliniques est faite dans une seconde partie. Ces composes sont obtenus par oxydation de derives de la triacetonamine. Les caracteristiques spectroscopiques ultra-violette, infra-rouge, et paramagnetique electronique de ces radicaux sont donnees. La grande inertie chimique du groupement nitroxyde a permis la syn-these d'un biradical stable par formation d'azine d'une cetone radicalaire, ce qui fait 1'objet de la troisieme partie. (auteur)

Investigating the Effect of Glass Ion Release on the Cytocompatibility, Antibacterial Eflcacy and Antioxidant Activity of Y2O3 / CeO2 doped SiO2-SrO-Na2O glasses

Directory of Open Access Journals (Sweden)

Placek L. M.

2018-02-01

Full Text Available The effect on ion release and cytocompatibility of Yttrium (Y and Cerium (Ce are investigated when substituted for Sodium (Na in a 0.52SiO2-0.24SrO-0.24-Na2OMOglass series (where MO= Y2O3 or CeO2. Glass leaching was evaluated through pH measurements and Inductive Coupled Plasma-Optical Emission Spectrometry (ICP-OES analysiswhere the extract pH increased during incubation (11.2 - 12.5. Ion release of Silicon (Si, Na and Strontium (Sr from the Con glass was at higher than that of glasses containing Y or Ce, and reached a limit after 1 day. Ion release from Y and Ce containing glasses reached a maximum of 1800 μg/mL, 1800 μg/mL, and 10 μg/mL for Si, Na, and Sr, respectively. Release of Y and Cewas below the ICP- OES detection limit 75% of bacteria at a 9% extract concentration. Antioxidant capacity (mechanism for neuroprotection was evaluated using the ABTS assay. All glasses had inherent radical oxygen species (ROS scavenging capability with Con reaching 9.5 mMTE.

Determination and modeling for the solubility of Na_2WO_4·2H_2O and Na_2MoO_4·2H_2O in the (Na"+ + MoO_4"2"− + WO_4"2"− + SO_4"2"− + H_2O) system

International Nuclear Information System (INIS)

Ning, Pengge; Xu, Weifeng; Cao, Hongbin; Xu, Hongbin

2016-01-01

Highlights: • The solubility of Na_2MoO_4·2H_2O and Na_2WO_4·2H_2O in Na_2MoO_4–Na_2WO_4–Na_2SO_4–H_2O were performed. • The solubility of sodium tungstate dihydrate in Na_2WO_4–Na_2SO_4–H_2O was determined. • The new model was established via regressing the published and the determined data. • The Pitzer parameter and the solubility product constant of the salt in solution were calculated. • The model was used to estimate the solubility of the sodium molybdate and sodium tungstate. - Abstract: The solubility of sodium tungstate dihydrate and sodium molybdate dihydrate in the (Na_2MoO_4 + Na_2WO_4 + Na_2SO_4 + H_2O) system was studied using experimental and calculated methods. The osmotic coefficient of sodium tungstate was fitted to calculate the thermodynamics parameters of (Na_2WO_4 + H_2O) system. The solubility of sodium tungstate dihydrate was determined using the dynamic method in Na_2WO_4–Na_2SO_4–H_2O to establish the new model which can provide an estimate the solubility of sodium tungstate dihydrate in various conditions, combined with the data published, the solubility of sodium tungstate dihydrate and the sodium molybdate dihydrate in quaternary system of (Na_2MoO_4 + Na_2WO_4 + Na_2SO_4 + H_2O) was estimated using the parameters of the two ternary systems of (Na_2WO_4 + Na_2SO_4 + H_2O) and (Na_2MoO_4 + Na_2SO_4 + H_2O). The results show that the AARD is always small and the calculated value is basically consistent with the experimental values for the system studied.

N,2,3,4-Tetrasubstituted Pyrrolidines through Tandem Lithium Amide Conjugate Addition/Radical Cyclization/Oxygenation Reactions

Czech Academy of Sciences Publication Activity Database

Kafka, František; Pohl, Radek; Císařová, I.; Mackman, R.; Bahador, G.; Jahn, Ullrich

2016-01-01

Roč. 2016, č. 22 (2016), s. 3862-3871 ISSN 1434-193X R&D Projects: GA ČR GA13-40188S Grant - others:COST(XE) CM1201 Institutional support: RVO:61388963 Keywords : tandem reactions * nitrogen heterocycles * Michael addition * radical reactions * cyclization * enolates Subject RIV: CC - Organic Chemistry Impact factor: 2.834, year: 2016

Photofragment imaging study of the CH2CCH2OH radical intermediate of the OH +allene reaction

Science.gov (United States)

Raman, Arjun S.; Justine Bell, M.; Lau, Kai-Chung; Butler, Laurie J.

2007-10-01

These velocity map imaging experiments characterize the photolytic generation of one of the two radical intermediates formed when OH reacts via an addition mechanism with allene. The CH2CCH2OH radical intermediate is generated photolytically from the photodissociation of 2-chloro-2-propen-1-ol at 193nm. Detecting the Cl atoms using [2+1] resonance-enhanced multiphoton ionization evidences an isotropic angular distribution for the Cl +CH2CCH2OH photofragments, a spin-orbit branching ratio for Cl(P1/22):Cl(P3/22) of 0.28, and a bimodal recoil kinetic energy distribution. Conservation of momentum and energy allows us to determine from this data the internal energy distribution of the nascent CH2CCH2OH radical cofragment. To assess the possible subsequent decomposition pathways of this highly vibrationally excited radical intermediate, we include electronic structure calculations at the G3//B3LYP level of theory. They predict the isomerization and dissociation transition states en route from the initial CH2CCH2OH radical intermediate to the three most important product channels for the OH +allene reaction expected from this radical intermediate: formaldehyde+C2H3, H +acrolein, and ethene+CHO. We also calculate the intermediates and transition states en route from the other radical adduct, formed by addition of the OH to the center carbon of allene, to the ketene+CH3 product channel. We compare our results to a previous theoretical study of the O +allyl reaction conducted at the CBS-QB3 level of theory, as the two reactions include several common intermediates.

Formation and transformations of radicals in frozen aqueous solutions of components of nucleic acids and H3PO4

International Nuclear Information System (INIS)

Minkhadzhidinova, D.R.; Chefranova, O.A.; Sharpatyj, V.A.

1977-01-01

Radiolysis of frozen aqueous solutions of 6-16 M H 3 PO 4 and 5 M NaH 2 PO 4 was studied, as well as radiolysis of these systems in the presence of nitrous bases and glucose. In aqueous solutions of H 3 PO 4 and NaH 2 PO 4 irradiated at 77 K, two groups of radicals formed as a result of interaction of the oxidative component of radiolysis of water with phosphate ions were identified. Their photolytic properties were studied. Primary products of radiolysis of the nitrous bases in phosphoric- acid solutions are anion- and cation-radicals. The molal absorption coefficients of the particles were determined

Electron impact excitation and ionization of laser-excited sodium atoms Na*(7d)

International Nuclear Information System (INIS)

Nienhaus, J.; Dorn, A.; Mehlhorn, W.; Zatsarinny, O.I.

1997-01-01

We have investigated the ejected-electron spectrum following impact excitation and ionization of laser-excited Na * (nl) atoms by 1.5 keV electrons. By means of two-laser excitation 3s → 3p 3/2 → 7d and subsequent cascading transitions about 8% (4%) of the target atoms were in excited states with n > 3 (7d). The experimental ejected-electron spectrum due to the decay of Auger and autoionization states of laser-excited atoms Na * (nl) with n = 4-7 has been fully interpreted by comprehensive calculations of the energies, cross sections and decay probabilities of the corresponding states. The various processes contributing to the ejected-electron spectrum are with decreasing magnitude: 2s ionization leading to 2s2p 6 nl Auger states, 2p → 3s excitation leading to 2p 5 3s( 1 P)nl autoionization states and 2s → 3l' excitation leading to 2s2p 6 3l'( 1 L)nl autoionization states. (Author)

Crystal Structure of the Sodium Cobaltate Deuterate Superconductor NaxCoO2o4xD2O (x=1/3)

OpenAIRE

Jorgensen, J. D.; Avdeev, M.; Hinks, D. G.; Burley, J. C.; Short, S.

2003-01-01

Neutron and x-ray powder diffraction have been used to investigate the crystal structures of a sample of the newly-discovered superconducting sodium cobaltate deuterate compound with composition Na0.31(3)CoO2o1.25(2)D2O and its anhydrous parent compound Na0.61(1)CoO2. The deuterate superconducting compound is formed by coordinating four D2O molecules (two above and two below) to each Na ion in a way that gives Na-O distances nearly equal to those in the parent compound. One deuteron of the D2...

On the Stability of NaO2 in Na-O2 Batteries.

Science.gov (United States)

Liu, Chenjuan; Carboni, Marco; Brant, William R; Pan, Ruijun; Hedman, Jonas; Zhu, Jiefang; Gustafsson, Torbjörn; Younesi, Reza

2018-04-25

Na-O 2 batteries are regarded as promising candidates for energy storage. They have higher energy efficiency, rate capability, and chemical reversibility than Li-O 2 batteries; in addition, sodium is cheaper and more abundant compared to lithium. However, inconsistent observations and instability of discharge products have inhibited the understanding of the working mechanism of this technology. In this work, we have investigated a number of factors that influence the stability of the discharge products. By means of in operando powder X-ray diffraction study, the influence of oxygen, sodium anode, salt, solvent, and carbon cathode were investigated. The Na metal anode and an ether-based solvent are the main factors that lead to the instability and decomposition of NaO 2 in the cell environment. This fundamental insight brings new information on the working mechanism of Na-O 2 batteries.

A esquerda radical no período pós-2009: nada de (muito novo em Portugal? = The radical left in the post-2009 period: nothing (very new in portugal?

Directory of Open Access Journals (Sweden)

Pereira, José Santana

2016-01-01

Full Text Available A crise económica que eclodiu nas democracias europeias periféricas a partir de 2009 teve, em vários países da Europa do Sul, consequências graves em termos de estabilidade governativa e dos sistemas partidários. Neste contexto, o caso português tem sido apontado como excecional, visto que o agravamento da situação económica e as suas consequências políticas não provocaram uma afirmação eleitoral sem precedentes de forças de esquerda radical (como na Espanha e na Grécia. Neste artigo, apresenta-se o panorama da esquerda radical em Portugal e procede-se à análise de algumas dimensões associadas a este fenómeno de maior estabilidade do sistema partidário português à esquerda, nomeadamente a ausência de um fenómeno SYRIZA ou Podemos, recorrendo a explicações de natureza económica, ligadas à cultura política e à natureza do sistema partidário consolidado nas últimas quadro décadas

Matrix-isolation and computational study of H{sub 2}CCCl and H{sub 2}CCBr radicals

Energy Technology Data Exchange (ETDEWEB)

Zhu, Cheng; Duarte, Luís; Khriachtchev, Leonid, E-mail: leonid.khriachtchev@helsinki.fi [Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki (Finland)

2016-08-21

We report on two new radicals, H{sub 2}CCCl and H{sub 2}CCBr, prepared in low-temperature noble-gas matrices and characterized using infrared spectroscopy. These radicals are made by UV photolysis of HCCCl and HCCBr and subsequent thermal annealing to mobilize hydrogen atoms in the matrices and promote their reaction with the residual precursor molecules. Three characteristic infrared bands are observed for each radical. The assignments are supported by quantum chemical calculations at the B3LYP and CCSD(T) levels of theory with the def2-TZVPPD basis set.

A Measurement of D+ and D(s) Production in e+ e- Annihilation at s** 1/2 = 29 GeV

Energy Technology Data Exchange (ETDEWEB)

Durrett, D.

2004-06-02

Measurements have been made of the production rates of D{sup +} and D{sub s} mesons via the channels D{sup +}-{bar K}*{sup 0} {ell}{sup +}{nu}{sub {ell}} and D{sub s} {yields} {phi}{pi} in e{sup +}e{sup -} annihilation at {radical}s = 29 GeV in 220 pb{sup -1} of data collected by the Mark II detector. The measurements assume the current branching ratios, measured predominantly at {radical}s {approx_equal} 10 GeV and by fixed target experiments. Measurements of the total production cross-sections times the appropriate branching ratios, which are independent of any other measurements, and an upper limit for the ratio of branching ratios, {Lambda}(D{sub s} {yields} {phi}{ell}{bar {nu}}{sub {ell}})/{Lambda}(D{sub s} {yields} {phi}{pi}) < .74 at 90% confidence level are presented. It is found that the production cross-section of D{sup +} mesons is {sigma}(e{sup +}e{sup -} {yields} D{sup +}X) = .24 {+-} .06 {+-} .04 nb while the production cross-section for D{sub s} mesons is {sigma}(e{sup +}e{sup -} {yields} D{sub s}X) = .10 {+-} .04 {+-} .03 nb. This corresponds to .23 {+-} .06 {+-} D{sup +}/hadronic event and .09 {+-} .04 {+-} .02 D{sub s}/hadronic event.

Investigation of the O+allyl addition/elimination reaction pathways from the OCH2CHCH2 radical intermediate

International Nuclear Information System (INIS)

FitzPatrick, Benjamin L.; Lau, K.-C.; Butler, Laurie J.; Lee, S.-H.; Lin, Jim Jr-Min

2008-01-01

These experiments study the preparation of and product channels resulting from OCH 2 CHCH 2 , a key radical intermediate in the O+allyl bimolecular reaction. The data include velocity map imaging and molecular beam scattering results to probe the photolytic generation of the radical intermediate and the subsequent pathways by which the radicals access the energetically allowed product channels of the bimolecular reaction. The photodissociation of epichlorohydrin at 193.3 nm produces chlorine atoms and c-OCH 2 CHCH 2 radicals; these undergo a facile ring opening to the OCH 2 CHCH 2 radical intermediate. State-selective resonance-enhanced multiphoton ionization (REMPI) detection resolves the velocity distributions of ground and spin-orbit excited state chlorine independently, allowing for a more accurate determination of the internal energy distribution of the nascent radicals. We obtain good agreement detecting the velocity distributions of the Cl atoms with REMPI, vacuum ultraviolet (VUV) photoionization at 13.8 eV, and electron bombardment ionization; all show a bimodal distribution of recoil kinetic energies. The dominant high recoil kinetic energy feature peaks near 33 kcal/mol. To elucidate the product channels resulting from the OCH 2 CHCH 2 radical intermediate, the crossed laser-molecular beam experiment uses VUV photoionization and detects the velocity distribution of the possible products. The data identify the three dominant product channels as C 3 H 4 O (acrolein)+H, C 2 H 4 +HCO (formyl radical), and H 2 CO (formaldehyde)+C 2 H 3 . A small signal from C 2 H 2 O (ketene) product is also detected. The measured velocity distributions and relative signal intensities at m/e=27, 28, and 29 at two photoionization energies show that the most exothermic product channel, C 2 H 5 +CO, does not contribute significantly to the product branching. The higher internal energy onset of the acrolein+H product channel is consistent with the relative barriers en route to

Investigation of the O+allyl addition/elimination reaction pathways from the OCH2CHCH2 radical intermediate

Science.gov (United States)

Fitzpatrick, Benjamin L.; Lau, Kai-Chung; Butler, Laurie J.; Lee, Shih-Huang; Lin, Jim-Min, Jr.

2008-08-01

These experiments study the preparation of and product channels resulting from OCH2CHCH2, a key radical intermediate in the O+allyl bimolecular reaction. The data include velocity map imaging and molecular beam scattering results to probe the photolytic generation of the radical intermediate and the subsequent pathways by which the radicals access the energetically allowed product channels of the bimolecular reaction. The photodissociation of epichlorohydrin at 193.3 nm produces chlorine atoms and c-OCH2CHCH2 radicals; these undergo a facile ring opening to the OCH2CHCH2 radical intermediate. State-selective resonance-enhanced multiphoton ionization (REMPI) detection resolves the velocity distributions of ground and spin-orbit excited state chlorine independently, allowing for a more accurate determination of the internal energy distribution of the nascent radicals. We obtain good agreement detecting the velocity distributions of the Cl atoms with REMPI, vacuum ultraviolet (VUV) photoionization at 13.8 eV, and electron bombardment ionization; all show a bimodal distribution of recoil kinetic energies. The dominant high recoil kinetic energy feature peaks near 33 kcal/mol. To elucidate the product channels resulting from the OCH2CHCH2 radical intermediate, the crossed laser-molecular beam experiment uses VUV photoionization and detects the velocity distribution of the possible products. The data identify the three dominant product channels as C3H4O (acrolein)+H, C2H4+HCO (formyl radical), and H2CO (formaldehyde)+C2H3. A small signal from C2H2O (ketene) product is also detected. The measured velocity distributions and relative signal intensities at m/e=27, 28, and 29 at two photoionization energies show that the most exothermic product channel, C2H5+CO, does not contribute significantly to the product branching. The higher internal energy onset of the acrolein+H product channel is consistent with the relative barriers en route to each of these product channels

Explicação e descrição no Behaviorismo radical: identidade ou dicotomia?

Directory of Open Access Journals (Sweden)

Carolina Laurenti

Full Text Available Este artigo examina uma inconsistência na proposta skinneriana com respeito às relações entre explicação e descrição. Em alguns momentos, Skinner identifica explicação e descrição, comprometendo-se com a máxima machiana " explicar é descrever" . Em outros momentos, Skinner desvincula os termos, considerando a descrição uma etapa preliminar do empreendimento científico, que deve ser complementada pela explicação. Argumenta-se, aqui, a favor da identidade entre explicação e descrição no Behaviorismo Radical com base nas influências de Mach na filosofia da ciência skinneriana. Defende-se ainda que essas influências se dão via selecionismo-pragmatismo, e não empirismo-descritivismo, contrastando com interpretações tradicionais das relações entre Mach e Skinner. Conclui-se que a identificação entre explicação e descrição parece expressar melhor as afinidades filosóficas do Behaviorismo Radical com o Pragmatismo.

Na+/Ca2+ exchange and Na+/K+-ATPase in the heart

Science.gov (United States)

Shattock, Michael J; Ottolia, Michela; Bers, Donald M; Blaustein, Mordecai P; Boguslavskyi, Andrii; Bossuyt, Julie; Bridge, John H B; Chen-Izu, Ye; Clancy, Colleen E; Edwards, Andrew; Goldhaber, Joshua; Kaplan, Jack; Lingrel, Jerry B; Pavlovic, Davor; Philipson, Kenneth; Sipido, Karin R; Xie, Zi-Jian

2015-01-01

This paper is the third in a series of reviews published in this issue resulting from the University of California Davis Cardiovascular Symposium 2014: Systems approach to understanding cardiac excitation–contraction coupling and arrhythmias: Na+ channel and Na+ transport. The goal of the symposium was to bring together experts in the field to discuss points of consensus and controversy on the topic of sodium in the heart. The present review focuses on cardiac Na+/Ca2+ exchange (NCX) and Na+/K+-ATPase (NKA). While the relevance of Ca2+ homeostasis in cardiac function has been extensively investigated, the role of Na+ regulation in shaping heart function is often overlooked. Small changes in the cytoplasmic Na+ content have multiple effects on the heart by influencing intracellular Ca2+ and pH levels thereby modulating heart contractility. Therefore it is essential for heart cells to maintain Na+ homeostasis. Among the proteins that accomplish this task are the Na+/Ca2+ exchanger (NCX) and the Na+/K+ pump (NKA). By transporting three Na+ ions into the cytoplasm in exchange for one Ca2+ moved out, NCX is one of the main Na+ influx mechanisms in cardiomyocytes. Acting in the opposite direction, NKA moves Na+ ions from the cytoplasm to the extracellular space against their gradient by utilizing the energy released from ATP hydrolysis. A fine balance between these two processes controls the net amount of intracellular Na+ and aberrations in either of these two systems can have a large impact on cardiac contractility. Due to the relevant role of these two proteins in Na+ homeostasis, the emphasis of this review is on recent developments regarding the cardiac Na+/Ca2+ exchanger (NCX1) and Na+/K+ pump and the controversies that still persist in the field. PMID:25772291

UV absorption spectra, kinetics and mechanisms of the self-reaction of CHF2O2 radicals in the gas phase at 298-K

DEFF Research Database (Denmark)

Nielsen, O.J.; Ellermann, T.; Bartkiewicz, E.

1992-01-01

The ultraviolet-absorption spectrum and the self-reaction of CHF2O2 radicals have been studied in the gas phase at 298 K using the pulse radiolysis technique and long-pathlength Fourier transform infrared spectroscopy. Absorption cross sections were quantified over the wavelength range 220-280 nm....... The measured cross section near the absorption maximum was sigma(CHF2O2)(240 nm) = (2.66 +/- 0.46) x 10(-18) cm2 molecule-1. The absorption cross section data were used to derive the observed self-reaction rate constant for the reaction CHF2O2 + CHF2O2 --> products, defined as d[R]/dt = 2k(1obs)[CHF2O2]2, k(1......obs) = (5.0 +/- 0.7) x 10(-12) cm3 molecule-1 s-1 (+/- 2-sigma). The only carbon-containing product observed by FTIR spectroscopy was FC(O)F. These results are discussed with respect to previous studies of peroxy radicals....

At NA2

CERN Multimedia

1977-01-01

One of the NA2 calorimeter sections is moved in. The NA2 calorimeter was divided in two halves, to the left and the right of the beam, each half consisting of sheets of passive high Z material interleaved with blades of plastic scintillators. The photo shows on the right, the upstream 'electron' module with eleven lead plates for a total radiation length of 20.

Chemical repair activity of free radical scavenger edaravone. Reduction reactions with dGMP hydroxyl radical adducts and suppression of base lesions and AP sites on irradiated plasmid DNA

International Nuclear Information System (INIS)

Hata, Kuniki; Katsumura, Yosuke; Urushibara, Ayumi; Yamashita, Shinichi; Lin Mingzhang; Muroya, Yusa; Shikazono, Naoya; Yokoya, Akinari; Fu Haiying

2015-01-01

Reactions of edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) with deoxyguanosine monophosphate (dGMP) hydroxyl radical adducts were investigated by pulse radiolysis technique. Edaravone was found to reduce the dGMP hydroxyl radical adducts through electron transfer reactions. The rate constants of the reactions were greater than 4 × 10 8 dm 3 mol -1 s -1 and similar to those of the reactions of ascorbic acid, which is a representative antioxidant. Yields of single-strand breaks, base lesions, and abasic sites produced in pUC18 plasmid DNA by gamma ray irradiation in the presence of low concentrations (10–1000 μmol dm -3 ) of edaravone were also quantified, and the chemical repair activity of edaravone was estimated by a method recently developed by the authors. By comparing suppression efficiencies to the induction of each DNA lesion, it was found that base lesions and abasic sites were suppressed by the chemical repair activity of edaravone, although the suppression of single-strand breaks was not very effective. This phenomenon was attributed to the chemical repair activity of edaravone toward base lesions and abasic sites. However, the chemical repair activity of edaravone for base lesions was lower than that of ascorbic acid. (author)

Na3Tb(PO4)2: Synthesis, crystal structure and greenish emitting properties

Science.gov (United States)

Zhao, Dan; Ma, Zhao; Liu, Bao-Zhong; Zhang, Rui-Juan; Wu, Zhi-Qiang; Wang, Jian; Duan, Pei-Gao

2018-03-01

A anhydrous orthoborate Na3Tb(PO4)2 has been prepared and its crystal structure was determined by X-Ray diffraction of a non-merohedral twinned single crystal. The results show that the compound crystallizes in monoclinic space group C2/c and the structure features a 3D framework containing PO4, NaO6, NaO7, NaO8 and TbO8 polyhedra. Under near-UV excitation (370 nm), Na3Tb(PO4)2 shows intense characteristic emission bands of Tb3+ (490 nm, 543 nm, 585 nm and 620 nm) with the CIE coordinate of (0.3062, 0.5901), corresponding to greenish color. The excitation spectrum covers a wide range from 340 nm to 390 nm, which indicates that phosphor Na3Tb(PO4)2 can be efficiently activated by near-UV LED ship.

Radical scavenging propensity of Cu2 +, Fe3 + complexes of flavonoids and in-vivo radical scavenging by Fe3 +-primuletin

Science.gov (United States)

Jabeen, Erum; Janjua, Naveed Kausar; Ahmed, Safeer; Murtaza, Iram; Ali, Tahir; Hameed, Shahid

2017-01-01

Cu2 + and Fe3 + complexes of three flavonoids (morin or mo, quercetin or quer and primuletin or prim) were synthesized with the objective of improving antioxidant capacities of flavonoids. The radical scavenging activities of pure flavonoids and their metal complexes were assayed to monitor their tendencies towards sequestering of radicals at physiological conditions. The scavenger potencies of metal-flavonoid complexes were significantly higher than those of the parent flavonoids. Further, influence of the solvent polarity on the radical capturing by flavonoids and their metal complexes was in favor for the polar solvent. Fe3 +-prim displayed its radical scavenging ability via up gradation of CAT and SOD activities in in-vivo antioxidant assays.

O Behaviorismo Radical como filosofia da mente Radical Behaviorism as philosophy of mind

Directory of Open Access Journals (Sweden)

Carlos Eduardo Lopes

2003-01-01

Full Text Available O Behaviorismo Radical de B. F. Skinner é constantemente acusado de eliminar a mente de sua explicação do comportamento humano. Uma análise do livro The Concept of Mind, de Gilbert Ryle, sugere a possibilidade de defender a existência de uma mente relacional, diferente da categoria de existência da mente defendida em interpretações cartesianas (mente substancial. A análise de alguns textos de Skinner sugere que o conceito de uma mente relacional também pode ser defendido no Behaviorismo Radical. Esse fato, culminaria na possibilidade de que, além de filosofia da Ciência do Comportamento, o Behaviorismo Radical, também pode ser uma filosofia da mente, o que traria conseqüências ao estudo e à aplicação da Análise do Comportamento.B. F. Skinner's Radical Behaviorism has been repeatedly accused of eliminating the mind from its explanation of human behavior. An analysis of Gilbert Ryle's book, The Concept of Mind, suggests the possibility of defending the existence of a relational mind, different from the category of existence of mind defended in Cartesian interpretations (substantial mind. The analysis of some texts of Skinner suggests that the concept of a relational mind can also be defended in Radical Behaviorism. This fact would lead to the possibility that, beyond a philosophy of Behavior Science, Radical Behaviorism may also be a philosophy of mind, which would bring consequences to the study and application of Analysis of Behavior.

cis-Thioindigo (TI) - a new ligand with accessible radical anion and dianion states. Strong magnetic coupling in the {[TI-(μ2-O),(μ-O)]Cp*Cr}2 dimers.

Science.gov (United States)

Konarev, Dmitri V; Khasanov, Salavat S; Shestakov, Alexander F; Fatalov, Alexey M; Batov, Mikhail S; Otsuka, Akihiro; Yamochi, Hideki; Kitagawa, Hiroshi; Lyubovskaya, Rimma N

2017-10-24

Reaction of decamethylchromocene (Cp* 2 Cr) with thioindigo (TI) yields a coordination complex {[TI-(μ 2 -O), (μ-O)]Cp*Cr} 2 ·C 6 H 14 (1) in which one Cp* ligand in Cp* 2 Cr is substituted by TI. TI adopts cis-conformation in 1 allowing the coordination of both carbonyl groups to chromium. Additionally, one oxygen atom of TI becomes a μ 2 -bridge for two chromium atoms to form {[TI-(μ 2 -O), (μ-O)]Cp*Cr} 2 dimers with a CrCr distance of 3.12 Å. According to magnetic data, diamagnetic TI 2- dianions and two Cr 3+ atoms with a high S = 3/2 spin state are present in a dimer allowing strong antiferromagnetic coupling between two Cr 3+ spins with an exchange interaction of -35.4 K and the decrease of molar magnetic susceptibility below 140 K. Paramagnetic TI˙ - radical anions with the S = 1/2 spin state have also been obtained and studied in crystalline {cryptand[2,2,2](Na + )}(TI˙ - ) (2) salt showing that both radical anion and dianion states are accessible for TI.

Sodium recognition by the Na+/Ca2+ exchanger in the outward-facing conformation.

Science.gov (United States)

Marinelli, Fabrizio; Almagor, Lior; Hiller, Reuben; Giladi, Moshe; Khananshvili, Daniel; Faraldo-Gómez, José D

2014-12-16

Na(+)/Ca(2+) exchangers (NCXs) are ubiquitous membrane transporters with a key role in Ca(2+) homeostasis and signaling. NCXs mediate the bidirectional translocation of either Na(+) or Ca(2+), and thus can catalyze uphill Ca(2+) transport driven by a Na(+) gradient, or vice versa. In a major breakthrough, a prokaryotic NCX homolog (NCX_Mj) was recently isolated and its crystal structure determined at atomic resolution. The structure revealed an intriguing architecture consisting of two inverted-topology repeats, each comprising five transmembrane helices. These repeats adopt asymmetric conformations, yielding an outward-facing occluded state. The crystal structure also revealed four putative ion-binding sites, but the occupancy and specificity thereof could not be conclusively established. Here, we use molecular-dynamics simulations and free-energy calculations to identify the ion configuration that best corresponds to the crystallographic data and that is also thermodynamically optimal. In this most probable configuration, three Na(+) ions occupy the so-called Sext, SCa, and Sint sites, whereas the Smid site is occupied by one water molecule and one H(+), which protonates an adjacent aspartate side chain (D240). Experimental measurements of Na(+)/Ca(2+) and Ca(2+)/Ca(2+) exchange by wild-type and mutagenized NCX_Mj confirm that transport of both Na(+) and Ca(2+) requires protonation of D240, and that this side chain does not coordinate either ion at Smid. These results imply that the ion exchange stoichiometry of NCX_Mj is 3:1 and that translocation of Na(+) across the membrane is electrogenic, whereas transport of Ca(2+) is not. Altogether, these findings provide the basis for further experimental and computational studies of the conformational mechanism of this exchanger.

Hyperfine interactions of a muoniated ethyl radical in supercritical CO2

International Nuclear Information System (INIS)

Cormier, Philip; Taylor, Becky; Ghandi, Khashayar

2009-01-01

A muoniated ethyl radical was studied in supercritical carbon dioxide. The muon and the proton hyperfine coupling constants were measured over temperatures ranging from 305 to 475 K, and a density range from 0.2 to 0.7 (g cm -3 ). A decrease was found in the muon hyperfine coupling constants as a function of the density, which can be attributed to the interaction between the CO 2 molecule and the p-orbital of the ethyl radical. The changes to the α-proton and β-proton hyperfine coupling constants with density are attributed to changes in the overall geometry in the formed radical. This system was modeled using quantum calculations.

Effect of free radicals and cultivation media on radiation sensitivities of escherichia coli and related bacteria

International Nuclear Information System (INIS)

Ito, Hitoshi

2000-01-01

Effects of gamma-irradiation on some strains of Escherichia coli, Salmonella enteritidis and Staphylococcus aureus were investigated in the presence of N 2 , N 2 O and O 2 and with the hydroxyl radical (OH) scavengers glycerol, polyethylene glycerol and formate. Injured cell membrane of bacteria was detected using with MacConkey agar for E. coli and S. enteritidis and 7% NaCl Triptic soy agar for St. aureus instead of Tryptic soy agar for recovery medium. From this study, addition of glycerol significantly reduced the sensitivity in all of strains, and cell membrane was not injured significantly except in radiation sensitive strain E. coli A4-1. When superoxide radicals (O 2 ) were generated during irradiation in the presence of formate, injured cell membrane increased significantly in all of strains. However, molecular oxygen (O 2 ) and OH radicals also had some effects on the damage of cell membrane. These results suggest that most radiation induced cell lethality was responsible to the cooperative effects of intracellular OH radicals and O 2 on DNA with lessor effect of damage on cell membrane by O 2 radicals, O 2 and OH radicals. On the radiation sensitive strain of E. coli, cell lethality occurred significantly by the injury of cell membrane compared with other strains. (author)

Esterified dendritic TAM radicals with very high stability and enhanced oxygen sensitivity.

Science.gov (United States)

Song, Yuguang; Liu, Yangping; Hemann, Craig; Villamena, Frederick A; Zweier, Jay L

2013-02-15

In this work, we have developed a new class of dendritic TAM radicals (TG, TdG, and dTdG) through a convergent method based on the TAM core CT-03 or its deuterated analogue dCT-03 and trifurcated Newkome-type monomer. Among these radicals, dTdG exhibits the best EPR properties with sharpest EPR singlet and highest O(2) sensitivity due to deuteration of both the ester linker groups and the TAM core CT-03. Like the previous dendritic TAM radicals, these new compounds also show extremely high stability toward various reactive species owing to the dendritic encapsulation. The highly charged nature of these molecules resulting from nine carboxylate groups prevents concentration-dependent EPR line broadening at physiological pH. Furthermore, we demonstrate that these TAM radicals can be easily derivatized (e.g., PEGylation) at the nine carboxylate groups and the resulting PEGylated analogue dTdG-PEG completely inhibits the albumin binding, thereby enhancing suitability for in vivo applications. These new dendritic TAM radicals show great potential for in vivo EPR oximetric applications and provide insights on approaches to develop improved and targeted EPR oximetric probes for biomedical applications.

THE QUIET SOLAR ATMOSPHERE OBSERVED AND SIMULATED IN Na I D1

International Nuclear Information System (INIS)

Leenaarts, J.; Rutten, R. J.; Carlsson, M.; Hansteen, V.; Reardon, K.

2010-01-01

The Na I D 1 line in the solar spectrum is sometimes attributed to the solar chromosphere. We study its formation in quiet-Sun network and internetwork. We first present high-resolution profile-resolved images taken in this line with the imaging spectrometer Interferometric Bidimensional Spectrometer at the Dunn Solar Telescope and compare these to simultaneous chromospheric images taken in Ca II 8542 A and Hα. We then model Na I D 1 formation by performing three-dimensional (3D) non-local thermodynamic equilibrium profile synthesis for a snapshot from a 3D radiation-magnetohydrodynamics simulation. We find that most Na I D 1 brightness is not chromospheric but samples the magnetic concentrations that make up the quiet-Sun network in the photosphere, well below the height where they merge into chromospheric canopies, with aureoles from 3D resonance scattering. The line core is sensitive to magneto-acoustic shocks in and near magnetic concentrations, where shocks occur deeper than elsewhere, and may provide evidence of heating deep within magnetic concentrations.

3D organic Na4C6O6/graphene architecture for fast sodium storage with ultralong cycle life.

Science.gov (United States)

Gu, Jianan; Gu, Yue; Yang, Shubin

2017-11-23

Sodium-ion batteries (SIBs) have aroused increasing interest as one of the most promising replacements for lithium-ion batteries (LIBs). Here, a novel organic-inorganic 3D Na 4 C 6 O 6 -graphene architecture was successfully fabricated from commercial Na 2 C 6 O 6 and for the first time applied for sodium storage. Hence, the 3D Na 4 C 6 O 6 -graphene architecture exhibits a high reversible capacity, good cyclic performance and high-rate capability for sodium storage.

Meltability in system of K2TaF7-NaF-NaCl-KCl

International Nuclear Information System (INIS)

Kartsev, V.E.; Kovalev, F.V.; Korshunov, B.G.

1975-01-01

Thermographic and visual-polythermal techniques were used to study the meltability in K 2 TaF 7 -NaF-NaCl-KCl system. The tetrahedron-forming sections NaF-NaCl-K 2 TaF 7 xKCl and NaF-K 2 TaF 7 xKCl-2K 2 TaF 7 xNaCl divide the concentration tetrahedron into three particular tetrahedra: NaF-K 2 TaF 7 xKCl-2K 2 TaF 7 xNaCl-K 2 TaF 7 , NaF-NaCl-K 2 TaF 7 xKCl-2K 2 TaF 7 xaCl, and NaF-NaCl-KCl-K 2 TaF 7 xKCl. Non-variant equilibrium points in all of the particular four-component systems have been determined

Na2MoO2As2O7

Directory of Open Access Journals (Sweden)

Raja Jouini

2012-12-01

Full Text Available Disodium molybdenum dioxide diarsenate, Na2MoO2As2O7, has been synthesized by a solid-state reaction. The structure is built up from MoAs2O12 linear units sharing corners to form a three-dimensional framework containing tunnels running along the a-axis direction in which the Na+ cations are located. In this framework, the AsV atoms are tetrahedrally coordinated and form an As2O7 group. The MoVI atom is displaced from the center of an octahedron of O atoms. Two Na+ cations are disordered about inversion centres. Structural relationships between different compounds: A2MoO2As2O7 (A = K, Rb, AMOP2O7 (A = Na, K, Rb; M = Mo, Nb and MoP2O7 are discussed.

Explosive hazards analysis of the eutectic solution NaK and KO2

International Nuclear Information System (INIS)

Commander, J.C.

1975-06-01

Planning, preparation, conductance, and evaluation of field tests are reported to determine the explosive hazards associated with the combining of the sodium-potassium eutectic alloy (NaK) with the superoxide of potassium (KO 2 ) under various conditions of state, contamination, and detonation initiation. The planning and preparation was conducted by Aerojet Nuclear Company (ANC) at the Idaho National Engineering Laboratory, and the explosive hazards testing was done by Cook Associates, Inc., at IRECO Chemicals Pelican Point Research and Development facility in Utah. The test results showed that binary combinations of pure NaK and KO 2 could not be made to detonate, although the mixtures will spontaneously ignite and burn. However, tertiary combinations of NaK, KO 2 plus a water or hydrocarbon contaminant produced explosive hazards under a variety of conditions. The work was performed as part of the Decontamination and Decommissioning (D and D) of the first Experimental Breeder Reactor (EBR-I) and was funded by 189c I-215. (U.S.)

Endoscopic extraperitoneal radical prostatectomy after radical resection of pT1-pT2 rectal cancer: a report of thirty cases.

Science.gov (United States)

Liu, Zhuo; Li, Dechuan; Chen, Yinbo

2017-01-01

Endoscopic extraperitoneal radical prostatectomy (EERPE) has gained popularity for the treatment of localized prostate cancer. However, prior complex lower abdominal or pelvic surgery can complicate subsequent EERPE. To date, there have been few reports on patients who underwent EERPE after radical resection of pT1-pT2 rectal cancer. To present our experience with EERPE in patients after radical resection of pT1-pT2 rectal carcinoma and introduce a simple and effective way to create an extraperitoneal working space. Thirty patients after radical resection of pT1-pT2 rectal carcinoma were treated with EERPE for biopsy-proven localized prostate cancer. Operation time, estimated blood loss, conversion to open surgery rate, transfusion rate and transurethral catheter time were recorded. Meanwhile, functional outcome (continence and potency) and oncological outcome were reviewed. The average operative time was 168 min. Mean blood loss was 195 ml. There was no need for conversion to open surgery or transfusion. The catheter was removed on postoperative day (POD) 7.8. After a mean follow-up time of 53.1 months, 3 patients had a prostate-specific antigen level relapse over 0.1 ng/ml. At the follow-up time, 26 patients were completely continent, and 4 needed 1-2 pads/day. Of the 6 patients who underwent neurovascular bundle preservation, none have experienced return of erections at the last follow-up time. Endoscopic extraperitoneal radical prostatectomy after radical resection of rectal carcinoma appears promising, with feasibility in experienced hands. The operative data, postoperative urinary incontinence and oncological outcomes appear encouraging, but the rate of erectile dysfunction seems to be disappointing.

Electronic Structure and Magnetic Interactions in the Radical Salt [BEDT-TTF]2[CuCl4].

Science.gov (United States)

Calzado, Carmen J; Rodríguez-García, Bárbara; Galán Mascarós, José Ramón; Hernández, Norge Cruz

2018-06-07

The magnetic behavior and electric properties of the hybrid radical salt [BEDT-TTF] 2 [CuCl 4 ] have been revisited through extended experimental analyses and DDCI and periodic DFT plane waves calculations. Single crystal X-ray diffraction data have been collected at different temperatures, discovering a phase transition occurring in the 250-300 K range. The calculations indicate the presence of intradimer, interdimer, and organic-inorganic π-d interactions in the crystal, a magnetic pattern much more complex than the Bleaney-Bowers model initially assigned to this material. Although this simple model was good enough to reproduce the magnetic susceptibility data, our calculations demonstrate that the actual magnetic structure is significantly more intricate, with alternating antiferromagnetic 1D chains of the organic BEDT-TTF + radical, connected through weak antiferromagnetic interactions with the CuCl 4 2- ions. Combination of experiment and theory allowed us to unambiguously determine and quantify the leading magnetic interactions in the system. The density-of-states curves confirm the semiconductor nature of the system and the dominant organic contribution of the valence and conduction band edges. This general and combined approach appears to be fundamental in order to properly understand the magnetic structure of these complex materials, where experimental data can actually be fitted from a variety of models and parameters.

Measurement of the energy flow at large pseudorapidities for {radical}(s)=0.9 TeV and {radical}(s)=7 TeV at the large hadron collider using the compact muon solenoid

Energy Technology Data Exchange (ETDEWEB)

Sen, Niladri

2011-11-15

Energy flow, dE/d{eta}, has been measured in proton-proton collisions at the lhc, for two centre-of-mass energies, {radical}(s)=0.9 TeV and 7 TeV, using an integrated luminosity of 239 {mu}b{sup -1} and 206 {mu}b{sup -1} respectively. The measurements were made in a previously unexplored phase space (3.15 < vertical stroke {eta} vertical stroke < 4.9) using the CMS detector for two separate event topologies: minimum bias events and events with a hard scale set by the transverse momentum of the jets in a di-jet system. Data from each of the measurements have been compared to leading order Monte Carlo pp-collision event generators that use k{sub T}{sup 2}-, Q{sup 2}- and angular-ordered parton showers. The forward energy ow measurements are shown to be sensitive to the models and tuning parameters in both their shape and magnitude. The necessity of underlying event models in order to describe data will be demonstrated. In addition, predictions from cosmic-ray event generators are shown to describe data consistently well for each of the measurements. (orig.)

Comparative analysis between clinical outcomes of primary radical resection and second completion radical resection for T2 gallbladder cancer: single-center experience.

Science.gov (United States)

Cho, Seong Yeon; Park, Sang-Jae; Kim, Seong Hoon; Han, Sung-Sik; Kim, Young-Kyu; Lee, Kwang-Woong

2010-07-01

Gallbladder (GB) cancer may be discovered incidentally by histopathologic examination following simple cholecystectomy. Incidental GB cancer > or =T2 or > or =N1 needs a second radical resection. It is a matter of concern whether the prognosis may be worse in patients with T2GB cancer who undergo a second radical resection than in those who undergo primary radical resection. Between March 2001 and March 2009, 21 patients underwent a one-step operation (OSO group), and 17 patients underwent a two-step operation (TSO group) for T2GB cancer. We compared clinicopathologic factors and survival between patients in the OSO group (n = 9) and those in the TSO group (n = 9) with T2N0M0 GB cancer and between patients in the OSO group (n = 12) and those in the TSO group (n = 8) with T2N1M0 GB cancer. Except for patient age, clinicopathologic factors as well as disease-free survival were not significantly different between the OSO group and the TSO group in the aforementioned cancer stages. Patient age was significantly higher in the OSO group than in the TSO group. Second completion radical resection following initial simple cholecystectomy (TSO) provided a survival benefit similar to that of primary radical surgery (OSO) for patients with both T2N0M0 and T2N1M0 GB cancers in our study.

Vacancy formation energy of Li(H,D) and Na(H,D) systems

International Nuclear Information System (INIS)

Islam, A.K.M.A.

1993-06-01

Vacancy defect formation energy (Schottky defect) of lighter hydrides and deuterides of alkali metals are discussed with reference to conductivity measurements and the recent computer simulation calculations. An empirical relation with Debye temperature is found to yield values of Schottky defect formation energies of Li(H,D) systems in agreement with experiments. The relationship is also utilized to obtain the formation energies for Na(H,D) systems for which experimental values are available in the literature. (author). 37 refs, 1 fig., 1 tab

Synthesis of diblock copolymers comprising poly(2-vinylpyridine-co-acrylonitrile) and polystyrene blocks by nitroxide-mediated radical polymerization

Czech Academy of Sciences Publication Activity Database

Lokaj, Jan; Poláková, Lenka; Holler, Petr; Starovoytova, Larisa; Štěpánek, Petr; Diat, O.

2007-01-01

Roč. 105, č. 3 (2007), s. 1616-1622 ISSN 0021-8995 R&D Projects: GA ČR GESON/03/E001 Institutional research plan: CEZ:AV0Z40500505 Keywords : 2-vinylpyridine-acrylonitrile copolymers * nitroxide-mediated radical copolymerization * chain extension Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.008, year: 2007

Free radical scavenging potency of quercetin catecholic colonic metabolites: Thermodynamics of 2H+/2e- processes.

Science.gov (United States)

Amić, Ana; Lučić, Bono; Stepanić, Višnja; Marković, Zoran; Marković, Svetlana; Dimitrić Marković, Jasmina M; Amić, Dragan

2017-03-01

Reaction energetics of the double (2H + /2e - ), i.e., the first 1H + /1e - (catechol→ phenoxyl radical) and the second 1H + /1e - (phenoxyl radical→ quinone) free radical scavenging mechanisms of quercetin and its six colonic catecholic metabolites (caffeic acid, hydrocaffeic acid, homoprotocatechuic acid, protocatechuic acid, 4-methylcatechol, and catechol) were computationally studied using density functional theory, with the aim to estimate the antiradical potency of these molecules. We found that second hydrogen atom transfer (HAT) and second sequential proton loss electron transfer (SPLET) mechanisms are less energy demanding than the first ones indicating 2H + /2e - processes as inherent to catechol moiety. The Gibbs free energy change for reactions of inactivation of selected free radicals indicate that catecholic colonic metabolites constitute an efficient group of more potent scavengers than quercetin itself, able to deactivate various free radicals, under different biological conditions. They could be responsible for the health benefits associated with regular intake of flavonoid-rich diet. Copyright © 2016 Elsevier Ltd. All rights reserved.

Kinetics of several oxygenated carbon-centered free radical reactions with NO2.

Science.gov (United States)

Rissanen, Matti P; Arppe, Suula L; Timonen, Raimo S

2013-05-16

Five oxygenated carbon-centered free radical reactions with nitrogen dioxide (NO2) have been studied in direct time-resolved measurements. Experiments were conducted in a temperature-controlled flow tube reactor coupled to a 193 nm exciplex laser photolysis and a resonance gas lamp photoionization mass spectrometer. Reactions were investigated under pseudofirst-order conditions, with the NO2 concentrations of the experiments in great excess over the initial radical concentrations ([R]0 CH3CO radical reactions with NO2 and, hence, includes the three smallest hydroxyalkyl radical species (CH2OH, CH2CH2OH, and CH3CHOH). The obtained rate coefficients are high with the temperature-dependent rate coefficients given by a formula k(T) = k300K × (T/300 K)(-n) as (in units of cm(3) molecule(-1) s(-1)): k(CH2OH + NO2) = (8.95 ± 2.70) × 10(-11) × (T/300 K)(-0.54±0.27) (T = 298-363 K), k(CH2CH2OH + NO2) = (5.99 ± 1.80) × 10(-11) × (T/300 K)(-1.49±0.45)(T = 241-363 K), k(CH3CHOH + NO2) = (7.48 ± 2.24) × 10(-11) × (T/300 K)(-1.36±0.41) (T = 266-363 K), k(CH3OCH2 + NO2) = (7.85 ± 2.36) × 10(-11) × (T/300 K)(-0.93±0.28) (T = 243-363 K), and k(CH3CO + NO2) = (2.87 ± 0.57) × 10(-11) × (T/300 K)(-2.45±0.49) (T = 241-363 K), where the uncertainties refer to the estimated overall uncertainties of the values obtained. The determined rate coefficients show negative temperature dependence with no apparent bath gas pressure dependence under the current experimental conditions (241-363 K and about 1-3 Torr helium). This behavior is typical for a radical-radical addition mechanism with no potential energy barrier above the energy of the separated reactants in the entrance channel of the reaction. Unfortunately the absence of detected product signals prevented gaining deeper insight into the reaction mechanism.

Ferromagnetic interactions in Ru(III)-nitronyl nitroxide radical complex: a potential 2p4d building block for molecular magnets.

Science.gov (United States)

Pointillart, Fabrice; Bernot, Kevin; Sorace, Lorenzo; Sessoli, Roberta; Gatteschi, Dante

2007-07-07

The reaction between [Ru(salen)(PPh3)Cl] and the 4-pyridyl-substituted nitronyl nitroxide radical (NITpPy) leads to the [Ru(salen)(PPh3)(NITpPy)](ClO4)(H2O)2 complex while the reaction with the azido anion (N3-) leads to the [Ru(salen)(PPh3)(N3)] complex 2 (where salen2- = N,N'-ethan-1,2-diylbis(salicylidenamine) and PPh3 = triphenylphosphine). Both compounds have been characterized by single crystal X-ray diffraction. The two crystal structures are composed by a [Ru(III)(salen)(PPh3)]+ unit where the Ru(III) ion is coordinated to a salen2- ligand and one PPh3 ligand in axial position. In 1 the Ru(III) ion is coordinated to the 4-pyridyl-substituted nitronyl nitroxide radical whereas in 2 the second axial position is occupied by the azido ligand. In both complexes the Ru(III) ions are in the same environment RuO2N3P, in a tetragonally elongated octhaedral geometry. The crystal packing of 1 reveals pi-stacking in pairs. While antiferromagnetic intermolecular interaction (J2 = 5.0 cm(-1)) dominates at low temperatures, ferromagnetic intramolecular interaction (J1 = -9.0 cm(-1)) have been found between the Ru(III) ion and the coordinated NITpPy.

Chemical repair activity of free radical scavenger edaravone: reduction reactions with dGMP hydroxyl radical adducts and suppression of base lesions and AP sites on irradiated plasmid DNA.

Science.gov (United States)

Hata, Kuniki; Urushibara, Ayumi; Yamashita, Shinichi; Lin, Mingzhang; Muroya, Yusa; Shikazono, Naoya; Yokoya, Akinari; Fu, Haiying; Katsumura, Yosuke

2015-01-01

Reactions of edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) with deoxyguanosine monophosphate (dGMP) hydroxyl radical adducts were investigated by pulse radiolysis technique. Edaravone was found to reduce the dGMP hydroxyl radical adducts through electron transfer reactions. The rate constants of the reactions were greater than 4 × 10(8) dm(3) mol(-1) s(-1) and similar to those of the reactions of ascorbic acid, which is a representative antioxidant. Yields of single-strand breaks, base lesions, and abasic sites produced in pUC18 plasmid DNA by gamma ray irradiation in the presence of low concentrations (10-1000 μmol dm(-3)) of edaravone were also quantified, and the chemical repair activity of edaravone was estimated by a method recently developed by the authors. By comparing suppression efficiencies to the induction of each DNA lesion, it was found that base lesions and abasic sites were suppressed by the chemical repair activity of edaravone, although the suppression of single-strand breaks was not very effective. This phenomenon was attributed to the chemical repair activity of edaravone toward base lesions and abasic sites. However, the chemical repair activity of edaravone for base lesions was lower than that of ascorbic acid. © The Author 2014. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

Does Metal Ion Complexation Make Radical Clocks Run Fast? An Experimental Perspective.

Science.gov (United States)

Abdel Latif, Marwa K; Spencer, Jared N; Paradzinsky, Mark; Tanko, James M

2017-12-28

The rate constant for the β-scission of the cumyloxyl radical (k β ) was measured in the presence of various added electrolytes in acetonitrile and DMSO solvent. The results show that in CH 3 CN, k β increases in the presence of added electrolyte, roughly paralleling the size of the cation: Li + > Mg 2+ ≈ Na + > n Bu 4 N + > no added electrolyte. As suggested by Bietti et al. earlier, this effect is attributable to stabilizing ion-dipole interactions in the transition state of the developing carbonyl group, a conclusion further amplified by MO calculations (gas phase) reported herein. Compared to the gas phase predictions, however, this effect is seriously attenuated in solution because complexation of the cation to the electrophilic alkoxyl radical (relative to the solvent, CH 3 CN) is very weak. Because the interaction of Li + and Na + is much stronger with DMSO than with CH 3 CN, addition of these ions has no effect on the rate of β-scission.

Radical cation spectroscopy of substituted alkyl phenyl ketones via tunnel ionization

Energy Technology Data Exchange (ETDEWEB)

Bohinski, Timothy; Moore Tibbetts, Katharine [Center for Advanced Photonics Research, Temple University, Philadelphia, PA 19122 (United States); Department of Chemistry, Temple University, Philadelphia, PA 19122 (United States); Munkerup, Kristin [Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø (Denmark); Tarazkar, Maryam [Center for Advanced Photonics Research, Temple University, Philadelphia, PA 19122 (United States); Department of Chemistry, Temple University, Philadelphia, PA 19122 (United States); Romanov, Dmitri A. [Center for Advanced Photonics Research, Temple University, Philadelphia, PA 19122 (United States); Department of Physics, Temple University, Philadelphia, PA 19122 (United States); Matsika, Spiridoula [Department of Chemistry, Temple University, Philadelphia, PA 19122 (United States); Levis, Robert J., E-mail: rjlevis@temple.edu [Center for Advanced Photonics Research, Temple University, Philadelphia, PA 19122 (United States); Department of Chemistry, Temple University, Philadelphia, PA 19122 (United States)

2014-10-17

Highlights: • Infrared strong field spectroscopy on (o, m, p)-methylacetophenone was performed. • Electronic resonance in the radical cations at 1370 nm produces benzoyl fragment. • Magnitude of resonance feature increases from ortho to meta to para isomer. • Hydrogen interactions and moment of inertia account for the trend across isomers. - Abstract: Mass spectra are measured for 2′-, 3′- and 4′-(ortho, meta and para) methyl substituted alkyl phenyl ketones excited at wavelengths ranging from 1200 to 1500 nm in the strong field regime. The selective loss of a methyl group from the acetyl group of the parent molecular ion upon excitation at ∼1370 nm is attributed to an electronic resonance between ground D{sub 0} and excited D{sub 2} state of the radical cation. Depletion of the parent molecular ion is enhanced as the methyl substituent is moved from the 2′ to 3′ to 4′ position on the phenyl ring with respect to the acetyl group. The phenyl-acetyl dihedral angle is the relevant coordinate enabling excitation to the dissociative D{sub 2} state. Calculations on the radical cation of 2′-methylacetophenone show two stable geometries with dihedral angles of 7 degrees and 63 degrees between the phenyl and acetyl groups. The barrier to rotation for the 2′ isomer limits population transfer to the D{sub 2} state. In contrast, calculations on the radical cations of 3′- and 4′-methylacetophenone reveal no rotational barrier to prevent population transfer to the excited state, which is consistent with the enhanced dissociation yield in comparison with the 2′ substitution. The enhanced dissociation of the 4′ isomer as compared to the 3′ isomer is attributed to its lower moment of inertia about the dihedral angle.

Free radicals in wood induced by γ-radiation

International Nuclear Information System (INIS)

Xu Honglin; Zhang Wenhui

1994-01-01

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

Phase equilibria in the NaF-CdO-NaPO{sub 3} system at 873 K and crystal structure and physico-chemical characterizations of the new Na{sub 2}CdPO{sub 4}F fluorophosphate

Energy Technology Data Exchange (ETDEWEB)

Aboussatar, Mohamed [Université Clermont Auvergne, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, UMR 6296 CNRS, BP 10448, F-63000 Clermont-Ferrand (France); Laboratoire de Physico-Chimie de l’État Solide, Faculté des Sciences de Sfax, Université de Sfax, BP 1171, 3000 Sfax (Tunisia); Mbarek, Aïcha [Laboratoire de Chimie Industrielle, Ecole Nationale d’Ingénieurs de Sfax, Université de Sfax, BP W3038, 3000 Sfax (Tunisia); Naili, Houcine [Laboratoire de Physico-Chimie de l’État Solide, Faculté des Sciences de Sfax, Université de Sfax, BP 1171, 3000 Sfax (Tunisia); El-Ghozzi, Malika [Université Clermont Auvergne, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, UMR 6296 CNRS, BP 10448, F-63000 Clermont-Ferrand (France); Chadeyron, Geneviève [Université Clermont Auvergne, Institut de Chimie de Clermont-Ferrand, UMR 6296 CNRS/UBP/SIGMA, BP 10448, F-63000 Clermont-Ferrand (France); Avignant, Daniel [Université Clermont Auvergne, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, UMR 6296 CNRS, BP 10448, F-63000 Clermont-Ferrand (France); Zambon, Daniel, E-mail: Daniel.Zambon@univ-bpclermont.fr [Université Clermont Auvergne, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, UMR 6296 CNRS, BP 10448, F-63000 Clermont-Ferrand (France)

2017-04-15

Isothermal sections of the diagram representing phase relationships in the NaF-CdO-NaPO{sub 3} system have been investigated by solid state reactions and powder X-ray diffraction. This phase diagram investigation confirms the polymorphism of the NaCdPO{sub 4} side component and the structure of the ß high temperature polymorph (orthorhombic, space group Pnma and unit cell parameters a=9.3118(2), b=7.0459(1), c=5.1849(1) Å has been refined. A new fluorophosphate, Na{sub 2}CdPO{sub 4}F, has been discovered and its crystal structure determined and refined from powder X-ray diffraction data. It exhibits a new 3D structure with orthorhombic symmetry, space group Pnma and unit cell parameters a=5.3731(1), b=6.8530(1), c=12.2691(2) Å. The structure is closely related to those of the high temperature polymorph of the nacaphite Na{sub 2}CaPO{sub 4}F and the fluorosilicate Ca{sub 2}NaSiO{sub 4}F but differs essentially in the cationic repartition since the structure is fully ordered with one Na site (8d) and one Cd site (4c). Relationships with other Na{sub 2}M{sup II}PO{sub 4}F (M{sup II}=Mg, Ca, Mn, Fe, Co, Ni) have been examined and the crystal-chemical and topographical analysis of these fluorophosphates is briefly reviewed. IR, Raman, optical and {sup 19}F, {sup 23}Na, {sup 31}P MAS NMR characterizations of Na{sub 2}CdPO{sub 4}F have been investigated. - Graphical abstract: The structure of the compound Na{sub 2}CdPO{sub 4}F, discovered during the study of the phase relationships in the NaF-CdO-NaPO{sub 3} system, has been determined and compared with other Na{sub 2}M{sup II}PO{sub 4}F fluorophosphates. - Highlights: • XRD analysis of the isothermal section of the NaF-CdO-NaPO{sub 3} system at 923 K. • Rietveld refinement of the high temperature polymorph β-NaCdPO{sub 4}. • Crystal structure of the new Na{sub 2}CdPO{sub 4}F fluorophosphate determined from powder XRD. • Crystal structure - composition relationships of Na{sub 2}M{sup II}PO{sub 4}F compounds

Stilbene dimer radical cations in the radiolyses of stilbenes and 1,2,3,4-tetraphenylcyclobutanes

International Nuclear Information System (INIS)

Tojo, Sachiko; Morishima, Kazuhiro; Ishida, Akito; Majima, Tetsuro; Takamuku, Setsuo

1995-01-01

The reaction of the stilbene radical cation formed by pulse radiolysis or γ-radiolyses is explained based on neutralization as well as the formation of a π-type stilbene dimer radical cation (π-St 2 +· ), converting to the σ-type St 2 +· (σ-St 2 +· ). The r-1, c-2, t-3, t-4-tetraphenylcyclobutane radical cation generated in a rigid matrix at 77 K which converted to σ-St 2 +· upon warming. Both r-1, c-2, t-3, t-4- and r-1, t-2, c-3, t-4-tetraphenylcyclobutane radical cations underwent photochemical cycloreversion to π-St 2 +· upon irradiation at wavelengths longer than 390 nm at 77 K, and converted to σ-St 2 +· upon warming. It is suggested that π-St 2 +· has overlapping arrangements of π-electrons, while σ-St 2 +· has radical and cation centers on the 1- and 4-positions of the C 4 linkage. (author)

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

Science.gov (United States)

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

2015-01-01

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

3-Hydroxylysine, a potential marker for studying radical-induced protein oxidation

DEFF Research Database (Denmark)

Morin, B; Bubb, W A; Davies, Michael Jonathan

1998-01-01

albumin (BSA) and human low-density lipoprotein (LDL)] and diseased human tissues (atherosclerotic plaques and lens cataractous proteins). This work was aimed at investigating oxidized lysine as a sensitive marker for protein oxidation, as such residues are present on protein surfaces, and are therefore...... likely to be particularly susceptible to oxidation by radicals in bulk solution. HO* attack on lysine in the presence of oxygen, followed by NaBH4 reduction, is shown to give rise to (2S)-3-hydroxylysine [(2S)-2,6-diamino-3-hydroxyhexanoic acid], (2S)-4-hydroxylysine [(2S)-2,6-diamino-4-hydroxyhexanoic...... acid], (2S, 5R)-5-hydroxylysine [(2S,5R)-2,6-diamino-5-hydroxyhexanoic acid], and (2S,5S)-5-hydroxylysine [(2S,5S)-2,6-diamino-5-hydroxyhexanoic acid]. 5-Hydroxylysines are natural products formed by lysyl oxidase and are therefore not good markers of radical-mediated oxidation. The other...

Free radical formation in deoxyguanosine-5'-monophosphate γ-irradiated in frozen solution. A computer-assisted analysis of temperature-dependent ESR spectra

International Nuclear Information System (INIS)

Gregoli, S.; Olast, M.; Bertinchamps, A.

1977-01-01

Deoxyguanosine-5'-monophosphate (dGMP) was γ-irradiated at 77 K in frozen aqueous solution and then annealed in a stepwise fashion up to the melting point. During this process, the primary radicals formed in DGMP at 77 K are progressively converted into secondary radical species. This is observed as changes in the spectrum intensity and conformation. Computer-assisted analysis of these temperature-dependent spectra permitted us to identify the transient radical species involved and to draw up single-radical concentration kinetics vs temperature. The radiation chemical behavior of dGMP was found to be quite similar to that of dAMP, investigated previously. In both these purine derivatives, radical anions are converted into radicals of H-addition to C-8, and radical cations are converted into radicals of OH-addition to the same position. In dGMP, however, the cationic channel is only induced under certain experimental conditions (alkaline pH, presence of electron scavengers). At neutral pH, G + radicals are quite stable and finally become deactivated without being converted into secondary GOH radicals. Specific deuterium substitution at carbon C-8, and irradiation in H 2 O or in D 2 O, confirmed that both H + and OH - attachments do occur at C-8, and that both the H + and OH - groups come from the aqueous medium

Vibronic Spectroscopy of the Phenylcyanomethyl Radical

Science.gov (United States)

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

2011-06-01

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

Controlled phase stability of highly Na-active triclinic structure in nanoscale high-voltage Na2-2xCo1+xP2O7 cathode for Na-ion batteries

Science.gov (United States)

Song, Hee Jo; Kim, Jae-Chan; Dar, Mushtaq Ahmad; Kim, Dong-Wan

2018-02-01

With the increasing demand for high energy density in energy-storage systems, a high-voltage cathode is essential in rechargeable Li-ion and Na-ion batteries. The operating voltage of a triclinic-polymorph Na2CoP2O7, also known as the rose form, is above 4.0 V (vs. Na/Na+), which is relatively high compared to that of other cathode materials. Thus, it can be employed as a potential high-voltage cathode material in Na-ion batteries. However, it is difficult to synthesize a pure rose phase because of its low phase stability, thus limiting its use in high-voltage applications. Herein, compositional-engineered, rose-phase Na2-2xCo1+xP2O7/C (x = 0, 0.1 and 0.2) nanopowder are prepared using a wet-chemical method. The Na2-2xCo1+xP2O7/C cathode shows high electrochemical reactivity with Na ions at 4.0 V, delivering high capacity and high energy density.

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

International Nuclear Information System (INIS)

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

1987-01-01

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

Separation of reaction mechanisms at low energy. Study of the reactions: {sup 27}Al(d,p) {sup 28}Al, {sup 24}Mg(d,p) {sup 25}Mg, and {sup 24}Mg(d, {alpha}) {sup 22}Na; Sur la separation des mecanismes de reaction a basse energie. Etude des reactions: {sup 27}Al(d,p) {sup 28}Al, {sup 24}Mg(d,p) {sup 25}Mg, et {sup 24}Mg(d, {alpha}) {sup 22}Na

Energy Technology Data Exchange (ETDEWEB)

Mermaz, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1966-06-01

The two sets of angular distributions of (d,p) reactions on Al and Mg, measured between 2 and 6 MeV, have given the possibility to test, in analysing the statistical fluctuations of cross-section, the validity of the separation of their mean values in two parts, one 'direct', another given by the statistical mechanism. With the same method of analysis we have studied excitation functions for several alpha groups of the reaction {sup 24}Mg(d, {alpha}) {sup 22}Na and given an evidence for an intermediate structure for the alpha channel leading to the 3. excited state of {sup 22}Na. The angular distribution of the wide resonance at 15.9 MeV in {sup 26}Al has been obtained. (author) [French] Les deux ensembles de distributions angulaires des reactions (d,p) sur Al et Mg, mesures entre 2 et 6 MeV, nous ont permis, en analysant les fluctuations statistiques de sections efficaces, de verifier la possibilite de la separation de leurs valeurs moyennes en deux composantes: l'une 'directe', l'autre due au mecanisme statistique. Avec la meme methode d'analyse nous avons etudie les fonctions d'excitation des premiers groupes alpha de la reaction {sup 24}Mg(d,{alpha}) {sup 22}Na et mis en evidence une structure intermediaire pour la voie de reaction aboutissant au 3eme niveau de {sup 22}Na. Nous avons obtenu la distribution angulaire de la resonance large situee a une energie d'excitation de 15,9 MeV dans {sup 26}Al. (auteur)

Separation of reaction mechanisms at low energy. Study of the reactions: {sup 27}Al(d,p) {sup 28}Al, {sup 24}Mg(d,p) {sup 25}Mg, and {sup 24}Mg(d, {alpha}) {sup 22}Na; Sur la separation des mecanismes de reaction a basse energie. Etude des reactions: {sup 27}Al(d,p) {sup 28}Al, {sup 24}Mg(d,p) {sup 25}Mg, et {sup 24}Mg(d, {alpha}) {sup 22}Na

Energy Technology Data Exchange (ETDEWEB)

Mermaz, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1966-06-01

The two sets of angular distributions of (d,p) reactions on Al and Mg, measured between 2 and 6 MeV, have given the possibility to test, in analysing the statistical fluctuations of cross-section, the validity of the separation of their mean values in two parts, one 'direct', another given by the statistical mechanism. With the same method of analysis we have studied excitation functions for several alpha groups of the reaction {sup 24}Mg(d, {alpha}) {sup 22}Na and given an evidence for an intermediate structure for the alpha channel leading to the 3. excited state of {sup 22}Na. The angular distribution of the wide resonance at 15.9 MeV in {sup 26}Al has been obtained. (author) [French] Les deux ensembles de distributions angulaires des reactions (d,p) sur Al et Mg, mesures entre 2 et 6 MeV, nous ont permis, en analysant les fluctuations statistiques de sections efficaces, de verifier la possibilite de la separation de leurs valeurs moyennes en deux composantes: l'une 'directe', l'autre due au mecanisme statistique. Avec la meme methode d'analyse nous avons etudie les fonctions d'excitation des premiers groupes alpha de la reaction {sup 24}Mg(d,{alpha}) {sup 22}Na et mis en evidence une structure intermediaire pour la voie de reaction aboutissant au 3eme niveau de {sup 22}Na. Nous avons obtenu la distribution angulaire de la resonance large situee a une energie d'excitation de 15,9 MeV dans {sup 26}Al. (auteur)

ESR of spin-trapped radicals from sugars. Reactions of hydroxyl radicals in aqueous solutions and. gamma. -radiolysis in the polycrystalline state

Energy Technology Data Exchange (ETDEWEB)

Kuwabara, M; Lion, Y; Riesz, P [National Cancer Inst., Bethesda, MD (USA)

1981-04-01

For glucose, mannose, and lactose which contain a -CH/sub 2/OH group at the C(5') position, a large secondary doublet (4.8 to 5.6 G) was observed for both solid state and aqueous experiments. However, for fructose, D-deoxyribose and D-ribose, which do not have a -CH/sub 2/OH group at the C(5') position, the large doublet was not found. The small doublet (1.2 to 1.5 G) was obtained from all the sugars for both the solid and the aqueous experiments. The 2.5 to 3.0 G doublet was only observed in the experiments with -irradiated solids, while the 4.3 G doublet was only produced by the reaction of OH radicals. It was inferred that the large (4.8 to 5.6 G) doublet can be assigned to the H-abstraction radical, -CHOH, from the -CH/sub 2/OH group at the C(5') position.

High-Performance Na-O2 Batteries Enabled by Oriented NaO2 Nanowires as Discharge Products.

Science.gov (United States)

Khajehbashi, S Mohammad B; Xu, Lin; Zhang, Guobin; Tan, Shuangshuang; Zhao, Yan; Wang, Lai-Sen; Li, Jiantao; Luo, Wen; Peng, Dong-Liang; Mai, Liqiang

2018-06-13

Na-O 2 batteries are emerging rechargeable batteries due to their high theoretical energy density and abundant resources, but they suffer from sluggish kinetics due to the formation of large-size discharge products with cubic or irregular particle shapes. Here, we report the unique growth of discharge products of NaO 2 nanowires inside Na-O 2 batteries that significantly boosts the performance of Na-O 2 batteries. For this purpose, a high-spin Co 3 O 4 electrocatalyst was synthesized via the high-temperature oxidation of pure cobalt nanoparticles in an external magnetic field. The discharge products of NaO 2 nanowires are 10-20 nm in diameter and ∼10 μm in length, characteristics that provide facile pathways for electron and ion transfer. With these nanowires, Na-O 2 batteries have surpassed 400 cycles with a fixed capacity of 1000 mA h g -1 , an ultra-low over-potential of ∼60 mV during charging, and near-zero over-potential during discharging. This strategy not only provides a unique way to control the morphology of discharge products to achieve high-performance Na-O 2 batteries but also opens up the opportunity to explore growing nanowires in novel conditions.

Gamow-Teller matrix elements from the C-12(d,He-2) and Mg-24(d,He-2) reactions at 170 MeV

NARCIS (Netherlands)

Baumer, C; Frekers, D; Schmidt, R; van den Berg, AM; Hannen, VM; Harakeh, MN; de Huu, MA; Wörtche, HJ; De Frenne, D; Hagemann, M; Heyse, J; Jacobs, E; Fujita, Y

The Mg-24(d,He-2)Na-24 and the C-12(d,He-2)B-12 charge-exchange reactions have been studied at an incident energy of 170 MeV. The two protons in the S-1(0)(pp) state (indicated as He-2) were both momentum analyzed and detected by the same spectrometer and detector. Background-free He-2 spectra with

Syntheses and study of pyrrolidinic nitroxide free radicals. Preparation of a nitroxide-type stable bi-radical; Synthese et etudes de radicaux libres nitroxydes pyrrolidiniques. Preparation d'un biradical stable du type nitroxyde

Energy Technology Data Exchange (ETDEWEB)

Dupeyre, R M [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires, Laboratoire de chimie organique physique

1967-12-01

Syntheses and study of pyrrolidinic nitroxide free radicals: These radicals are obtained by oxidation, with hydrogen peroxide, of pyrrolidinic amines prepared from triacetonamine by ring contraction. The U. V,, I. R, and E.P.R. spectral characteristics have been determined. The oxidation of these amines with hydrogen peroxide has led also to rupture of the pentagonal ring; some of the decomposition products have been identified. The high chemical stability of the nitroxide group has made it possible to synthesize and study a stable bi-radical. (author) [French] Syntheses et etudes de radicaux libres nitroxydes pyrrolidiniques: Ces radicaux sont obtenus par oxydation l'eau oxygenee d'amines pyrrolidiniques preparees a partir de la triacetonamine par contraction de cycle. Les caracteristiques spectroscopiques ultra-violettes, infra-rouge et resonance paramagnetique sont determinees. Cependant, 1'oxydation de ces amines a l'eau oxygenee a entraine la coupure du cycle pentagonal et identification de certaines substances de decomposition obtenues. La grande stabilite chimique de groupement nitroxyde a permis la synthese et l'etude d'un biradical stable. (auteur)

SnSe2 2D Anodes for Advanced Sodium Ion Batteries

KAUST Repository

Zhang, Fan; Xia, Chuan; Zhu, Jiajie; Ahmed, Bilal; Liang, Hanfeng; Velusamy, Dhinesh Babu; Schwingenschlö gl, Udo; Alshareef, Husam N.

2016-01-01

A simple synthesis method to prepare pure SnSe2 nanosheet anodes for Na ion batteries is reported. The SnSe2 2D sheets achieve a stable and reversible specific capacity of 515 mA h g-1 after 100 cycles, with excellent rate performance. The sodiation

Investigating Pigment Radicals in Black Rice Using HPLC and Multi-EPR.

Science.gov (United States)

Nakagawa, Kouichi; Maeda, Hayato

2017-01-01

We investigated the location and distribution of paramagnetic species in black and white rice using electron paramagnetic resonance (EPR), X-band (9 GHz) EPR imaging (EPRI), and HPLC. EPR primarily detected two paramagnetic species in black rice, which were identified as a stable radical and Mn 2+ species, based on the g values and hyperfine components of the EPR signals. The signal from the stable radical appeared at g ≈ 2.00 and was relatively strong and stable. Subsequent noninvasive two-dimensional (2D) EPRI revealed that this stable radical was primarily located in the pigmented region of black rice, while very few radicals were observed in the rice interior. Pigments extracted from black rice were analyzed using HPLC; the major compound was found to be cyanidin-3-glucoside. EPR and HPLC results indicate that the stable radical was only found within the pigmented region of the rice, and that it could either be cyanidin-3-glucoside, or one of its oxidative decomposition products.

Izrada 2D video igre za iOS platformu

OpenAIRE

Kampuš, Dominik

2016-01-01

Tema ovog završnog rada temelji se na izradi 2D video igre za iOS mobilni uređaj te njezinoj demonstraciji na istom. Kroz rad su opisane sve bitne funkcije GameSalad Creator-a koje su potrebne kod izrade igre bazirane na 2 dimenzije. Također se prolazi kroz iOS operativni sustav, što je on i kako se razvijao. Spominje se i tema koja govori općenito o igrama na mobilnim uređajima. U završnom dijelu rada prikazan je postupak izrade, koje funkcije programa se točno koriste i kako se igra može te...

Study of the solubility, viscosity and density in Na+, Zn2+/Cl− − H2O, Na+ − Zn2+ − (H2PO2)− − H2O, Na+, Cl−/(H2PO2)− − H2O, and Zn2+, Cl−/(H2PO2)− − H2O ternary systems, and in Na+, Zn2+/Cl−, (H2PO2)−//H2O reciprocal quaternary system at 273.15 K

International Nuclear Information System (INIS)

Adiguzel, Vedat; Erge, Hasan; Alisoglu, Vahit; Necefoglu, Hacali

2014-01-01

Highlights: • The physicochemical properties of ternary and one quaternary have been studied. • Reciprocal quaternary systems’ solubility and phase equilibrium have been studied. • In all systems the solid phases have been found. • It was found that Zn(H 2 PO 2 ) 2 salt contains 70% of the general crystallization field. - Abstract: The solubility and the physicochemical properties (density, viscosity) in the Na-Zn- Cl-H 2 O), (Na + Zn + H 2 PO 2 + H 2 O), (Na + Cl + H 2 PO 2 + H 2 O), and (Zn + Cl + H 2 PO 2 + H 2 O) ternaries, and in Na + , Zn 2+ /Cl − , (H 2 PO 2 ) − //H 2 O reciprocal quaternary systems at T = 273.15 K were investigated by using the isothermal method. The diagrams of ternary salts systems, (NaCl + ZnCl 2 + H 2 O), (NaCl + NaH 2 PO 2 + H 2 O), (NaH 2 PO 2 + Zn(H 2 PO 2 ) 2 + H 2 O), (ZnCl 2 + Zn(H 2 PO 2 ) 2 + H 2 O), are plotted in figures 1–4. However, whole ions of reciprocal quaternary salt systems are plotted in figure 5. Additionally, the density and viscosity values of ternary systems vs. their corresponding composition values in weight per cent are plotted in figures 6–10. At the (i) (ZnCl 2 + Zn(H 2 PO 2 ) 2 + H 2 O), (ii) (NaCl + ZnCl 2 + H 2 O), (iii) (NaCl + NaH 2 PO 2 + H 2 O), (iv) (NaH 2 PO 2 + Zn(H 2 PO 2 ) 2 + H 2 O) ternary systems the solid phase compositions have been determined as: (i) Zn(H 2 PO 2 ) 2 ⋅ H 2 O, Zn(H 2 PO 2 ) 2 , ZnCl 2 ⋅ 2H 2 O, (ii) NaCl, 2NaCl ⋅ ZnCl 2 ⋅ 2H 2 O, and ZnCl 2 ⋅ 2H 2 O, (iii) NaCl and NaH 2 PO 2 ⋅ H 2 O, (iv) Zn(H 2 PO 2 ) 2 ⋅ H 2 O and NaH 2 PO 2 ⋅ H 2 O, respectively. On the other hand reciprocal quaternary system was observed as: ZnCl 2 ⋅ 2H 2 O, 2NaCl ⋅ ZnCl 2 ⋅ 2H 2 O, Zn(H 2 PO 2 ) 2 ⋅ H 2 O, NaH 2 PO 2 ⋅ H 2 O, NaCl. According to results, the least soluble salt was Zn(H 2 PO 2 ) 2 . The crystallization field of this salt, being the largest in comparison with those of other salts, occupied 70% of the general crystallization field

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

Energy Technology Data Exchange (ETDEWEB)

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

2009-08-01

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

Antioxidant Capacity, Radical Scavenging Kinetics and Phenolic ...

African Journals Online (AJOL)

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

Atmospheric degradation of 2- nitrobenzaldehyde: Photolysis and reaction with OH radicals

Science.gov (United States)

Bouya, H.; Al Rashidi, M.; Roth, E.; Salghi, R.; Chakir, A.

2017-12-01

This work presents an experimental study of the gas phase kinetics of 2-nitrobenzaldehyde (2-NBA) photolysis and oxidation by OH radicals. The experiments were carried out in an atmospheric simulation chamber coupled to an FTIR spectrometer and CG/MS. The UV spectra of 2-NBA were also measured and the experimentally determined absorption cross sections were used to estimate the atmospheric photo-dissociation constant of 2-NBA with a global quantum yield of 0.5. The obtained results indicate that 2-NBA is a highly photolysable. A mechanism of 2-NBA photolysis was proposed based on the identification of photolysis degradation products. The kinetics of oxidation of 2-NBA by OH radicals was investigated over the temperature range 308-352 K. The obtained rate coefficients exhibits slight negative temperature dependence and the Arrhenius expression obtained is as follows: kOH+2-NBA(T)= (7.00 ± 3.40) × 10-12exp (577 ± 156/T) cm3 molecule-1 s-1. The calculated rate coefficients lead to tropospheric lifetimes of 2-NBA that are in the order of a few minutes, relative to photolysis, or a few hours, relative to oxidation by OH radicals.

Synthesis and visible-light-driven photocatalytic activity of p–n heterojunction Ag_2O/NaTaO_3 nanocubes

International Nuclear Information System (INIS)

Yang, Songbo; Xu, Dongbo; Chen, Biyi; Luo, Bifu; Yan, Xu; Xiao, Lisong; Shi, Weidong

2016-01-01

Highlights: • We firstly report a facile way to prepare the visible-light-driven Ag_2O/NaTaO_3p–n heterojunction by chemical precipitation method. • The Ag_2O/NaTaO_3 heterojunction shows the highest photocatalytic activity than the pure NaTaO_3 and Ag_2O nanoparticles under visible light. • The enhancement of the heterojunction photocatalytic activity was discussed and the photocatalytic mechanism was tested in our paper. • In summary, we think that the Ag_2O/NaTaO_3 heterojunction with the strong visible light absorption and efficient photocatalytic activity have been extended application in photocatalysis for organic dyes pollutants degradation and purification of water. - Abstract: The constructing of p–n heterojunction photocatalytic system has received much attention in environmental purification and hydrogen generation from water. In this study, an efficient visible-light-driven p–n heterojunction Ag_2O/NaTaO_3 was successfully prepared by chemical precipitation method at room temperature. It showed an enhanced photocatalytic activity for the degradation of rhodamine B (RhB) under visible-light irradiation, much higher than those of either individual Ag_2O or NaTaO_3. The reactive species scavenger results indicated the superoxide anion radicals (·O"2"−) played key roles in RhB decoloration. From the experimental results and the relative band gap position of these semiconductors, a detailed possible photocatalytic mechanism of the Ag_2O/NaTaO_3 heterojunction under visible light was proposed. The enhancement of the photocatalytic activity was attributed to the interfacial electronic interaction between NaTaO_3 and Ag_2O and the high migration efficiency of photogenerated carriers.

Atmospheric chemistry of cyc-CF2CF2CF2CH=CH-: Kinetics, products, and mechanism of gas-phase reaction with OH radicals, and atmospheric implications

Science.gov (United States)

Guo, Qin; Zhang, Ni; Uchimaru, Tadafumi; Chen, Liang; Quan, Hengdao; Mizukado, Junji

2018-04-01

The rate constants for the gas-phase reactions of cyc-CF2CF2CF2CH=CH- with OH radicals were determined by a relative rate method between 253 and 328 K. The rate constant k1 at 298 K was measured to be (1.08 ± 0.04) × 10-13 cm3 molecule-1 s-1, and the Arrhenius expression was k1 = (3.72 ± 0.14) × 10-13 exp [(-370 ± 12)/T]. The atmospheric lifetime of cyc-CF2CF2CF2CH=CH- was calculated to be 107 d. The products and mechanism for the reaction of cyc-CF2CF2CF2CH=CH- with OH radicals were also investigated. CO, CO2, and COF2 were identified as the main carbon-containing products following the OH-initiated reaction. Moreover, the radiative efficiency (RE) was determined to be 0.143 W m-2 ppb-1, and the global warming potentials (GWPs) for 20, 100, and 500 yr were 54, 15, and 4, respectively. The photochemical ozone creation potential of the title compound was estimated to be 1.3.

Molecular dynamics investigation of Na+ in Na2Ni2TeO6

International Nuclear Information System (INIS)

Sau, Kartik; Kumar, P. Padma

2014-01-01

An inter-atomic potential for Na 2 Ni 2 TeO 6 in the Parrinello- Rahman-Vashishta (PRV) model is parameterized empirically. The potential reproduces variety of structural and transport properties of that material in good agreement with recent experimental results. The study provides fresh insights on the migration channels and mechanism of Na + in the system

Thermochemical properties for isooctane and carbon radicals: computational study.

Science.gov (United States)

Snitsiriwat, Suarwee; Bozzelli, Joseph W

2013-01-17

Thermochemical properties for isooctane, its internal rotation conformers, and radicals with corresponding bond energies are determined by use of computational chemistry. Enthalpies of formation are determined using isodesmic reactions with B3LYP density function theory and composite CBS-QB3 methods. Application of group additivity with comparison to calculated values is illustrated. Entropy and heat capacities are determined using geometric parameters, internal rotor potentials, and frequencies from B3LYP/6-31G(d,p) calculations for the lowest energy conformer. Internal rotor potentials are determined for the isooctane parent and for the primary, secondary, and tertiary radicals in order to identify isomer energies. Intramolecular interactions are shown to have a significant effect on the enthalpy of formation of the isooctane parent and its radicals. The computed standard enthalpy of formation for the lowest energy conformers of isooctane from this study is -54.40 ± 1.60 kcal mol(-1), which is 0.8 kcal mol(-1) lower than the evaluated experimental value -53.54 ± 0.36 kcal mol(-1). The standard enthalpy of formation for the primary radical for a methyl on the quaternary carbon is -5.00 ± 1.69 kcal mol(-1), for the primary radical on the tertiary carbon is -5.18 ± 1.69 kcal mol(-1), for the secondary isooctane radical is -9.03 ± 1.84 kcal mol(-1), and for the tertiary isooctane radical is -12.30 ± 2.02 kcal mol(-1). Bond energy values for the isooctane radicals are 100.64 ± 1.73, 100.46 ± 1.73, 96.41 ± 1.88 and 93.14 ± 2.05 kcal mol(-1) for C3•CCCC2, C3CCCC2•, C3CC•CC2, and C3CCC•C2, respectively. Entropy and heat capacity values are reported for the lowest energy homologues.

Photoinduced Reversible Morphological Transformation of Azobenzene-Containing Pseudo-2D Polymers.

Science.gov (United States)

Li, Zili; Tang, Miao; Jiang, Chen; Bai, Ruke; Bai, Wei

2018-05-02

2D polymer sheets containing azobenzene are successfully prepared by a facile strategy of "2D self-assembly polymerization (2DSP)" via free radical polymerization in solution. A bola amphiphile containing azobenzene as a novel monomer is designed and synthesized. The results indicate that single-layer covalent pseudo-2D polymers on a micrometer scale are obtained after polymerization with vinyl monomers. Moreover, the 2D polymer sheets are highly sensitive to UV light due to incorporation of azobenzene groups into the polymer. Upon alternative irradiation with UV and visible light, the morphological transformation between sheets and rolled-up nanotubes can be achieved based on the reversible trans-to-cis photoisomerization of azobenzene units in the 2D polymer sheets. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Radiolytic reduction of nifurtimose by CO2-· free radicals

International Nuclear Information System (INIS)

Filali-Mouhim, A.; Champion, B.; Jore, D.; Ferradini, C.; Hickel, B.

1991-01-01

Nifurtimox is an antiparasitic drug often used in the treatment of the Chagas disease. Its therapeutic action seems to involve its monoelectronic reduction leading to a reduced radical capable of providing superoxide anion by reaction with oxygen. The oxidation reduction mechanisms involved in this action have been studied by steady state and pulse radiolysis methods. This study is devoted to the monoelectronic exchanges observed in the absence of air, the reducing radicals being the CO 2 - · anions [fr

NaCl islands decorated with 2D or 3D 3,4,9,10-perylene-tetracarboxylic-dianhydride nanostructures

International Nuclear Information System (INIS)

Sun Xiaonan; Silly, Fabien

2010-01-01

The formation of PTCDA (3,4,9,10-perylene-tetracarboxylic-dianhydride) nanostrutures on Au(1 1 1)-(22x√(3)) covered with NaCl islands has been studied using scanning tunneling microscopy (STM). Atomically resolved STM images show that NaCl grows as (1 0 0)-terminated layers on Au(1 1 1)-(22x√(3)). Local atomic hexagonal packing has also been observed in the NaCl(1 0 0) layer. At submonolayer NaCl coverage, PTCDA forms two-dimensional islands on the Au(1 1 1) surface and nucleate preferentially at the NaCl island step edges. When the Au surface is fully covered with NaCl layers, PTCDA molecules form three-dimensional molecular clusters decorating the step edges of NaCl layers.

Radical Transversal Lightlike Submanifolds of Indefinite Para-Sasakian Manifolds

OpenAIRE

Shukla S.S.; Yadav Akhilesh

2014-01-01

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

Time-resolved FTIR emission studies of laser photofragmentation and radical reactions

Energy Technology Data Exchange (ETDEWEB)

Leone, S.R. [Univ. of Colorado, Boulder (United States)

1993-12-01

Recent studies have focused specifically on collision processes, such as single collision energy transfer, reaction dynamics, and radical reactions. The authors employ novel FTIR techniques in the study of single collision energy transfer processes using translationally fast H atom, as well as radical-radical reactions, e.g. CH{sub 3} + O, CF{sub 3} + H(D), and Cl + C{sub 2}H{sub 5}. The fast atoms permit unique high energy regions of certain transition states of combustion species to be probed for the first time.

Observation and Modelling of the OH, HO2 and RO2 Radicals at a Regional Site of Beijing in Winter 2016.

Science.gov (United States)

Tan, Z.; Lu, K.; Ma, X.; Bohn, B.; Hofzumahaus, A.; Broch, S.; Fuchs, H.; Holland, F.; Liu, Y.; Li, X.; Novelli, A.; Rohrer, F.; Wang, H.; Wu, Y.; Shao, M.; Zeng, L.; Kiendler-Scharr, A.; Wahner, A.; Zhang, Y.

2017-12-01

A comprehensive field campaign was carried out in winter 2016 in the campus of UCAS (University of Chinese Academy of Science), located in a small town 60 km northeast of urban Beijing. Concentrations of OH, HO2 and RO2 radicals as well as the total OH reactivity were measured by a laser induced fluorescence instrument. Maximum hourly averaged OH, HO2 and RO2 radical concentrations were (3±2)×106cm-3, (8±6)×107 cm-3 and (7±5)×107 cm-3, respectively. These radical concentrations were smaller than those observed during summer because of the reduced solar radiation. A chemical modulation device to separate atmospheric OH radicals from any interfering species was applied for few days showing negligible interference for both clean and polluted air masses.HONO and HCHO photolysis were found to be the most important primary sources of ROx radicals. CO and NOx were the important OH reactants which contributed more than half of the total OH reactivity. The relative high OH concentrations in polluted episode enabled a fast oxidation of fresh emitted pollutants and the formation of secondary air products. The observed radical concentrations were compared with the results from a chemical box model. The model is capable of reproducing radical concentrations for moderate NOx conditions but larger discrepancies are observed for both low and high NOx regimes for the peroxy radical concentrations. The underestimation of RO2 radical concentrations for high NOx conditions is discussed in the context of recent campaigns.

Radiolytic oxidation of tamoxifen using the free radicals .OH and (or) HO2

International Nuclear Information System (INIS)

Leguene, C.; Clavere, P.; Jore, D.; Gardes-Albert, M.

2001-01-01

Tamoxifen is the most widely used antiestrogen in the treatment of breast cancer. In this work, we have studied its antioxidant properties. We have investigated the ability of tamoxifen to scavenge, in vitro, . OH and (or) HO 2 . free radicals that are produced by water radiolysis. Aqueous solutions of tamoxifen of concentrations ranging between 10 -5 and 2.5 x 10 -5 M have been irradiated (γ 137 Cs) in aerated acidic medium (H 3 PO 4 10 -3 M or HCOOH 10 -1 M). The results show that tamoxifen reacts quantitatively with . OH free radicals but does not react with HO 2 . free radicals under our experimental conditions. (author)

Hyperfine interactions of a muoniated ethyl radical in supercritical CO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Cormier, Philip; Taylor, Becky [Department of Chemistry, Mount Allison University, Sackville, New Brunswick, E4L 1G8 (Canada); Ghandi, Khashayar, E-mail: kghandi@mta.c [Department of Chemistry, Mount Allison University, Sackville, New Brunswick, E4L 1G8 (Canada)

2009-04-15

A muoniated ethyl radical was studied in supercritical carbon dioxide. The muon and the proton hyperfine coupling constants were measured over temperatures ranging from 305 to 475 K, and a density range from 0.2 to 0.7 (g cm{sup -3}). A decrease was found in the muon hyperfine coupling constants as a function of the density, which can be attributed to the interaction between the CO{sub 2} molecule and the p-orbital of the ethyl radical. The changes to the alpha-proton and beta-proton hyperfine coupling constants with density are attributed to changes in the overall geometry in the formed radical. This system was modeled using quantum calculations.

Resonance Raman Spectrum of the Transient (SCN)2 Free Radical Anion

DEFF Research Database (Denmark)

Wilbrandt, Robert Walter; Jensen, N. H.; Pagsberg, Palle Bjørn

1979-01-01

The resonance Raman spectrum of the transient species (λmax = 475 nm, τ½ = 1.6 μs) formed by pulse radiolysis of aqueous solutions of thiocyanate, SCN2−, is reported. The spectrum is discussed in terms of the previous assignment of this transient to the radical anion, (SCN)−2. The observed...... vibrational frequencies of the radical anion are consistent with substantial weakening of the S---S and the Ctriple bond; length as m-dashN bonds are compared with neutral thiocyanogen....

Synthesis of Li(x)Na(2-x)Mn2S3 and LiNaMnS2 through redox-induced ion exchange reactions

International Nuclear Information System (INIS)

Luthy, Joshua A.; Goodman, Phillip L.; Martin, Benjamin R.

2009-01-01

Na 2 Mn 2 S 3 was oxidatively deintercalated using iodine in acetonitrile to yield Na 1.3 Mn 2 S 3 , with lattice constants nearly identical to that of the reactant. Lithium was then reductively intercalated into the oxidized product to yield Li 0.7 Na 1.3 Mn 2 S 3 . When heated, this metastable compound decomposed to form a new crystalline compound, LiNaMnS 2 , along with MnS and residual Na 2 Mn 2 S 3 . Single crystal X-ray diffraction structural analysis of LiNaMnS 2 revealed that this compound crystallizes in P-3m1 with cell parameters a=4.0479(6) A, c=6.7759(14) A, V=96.15(3) A 3 (Z=1, wR2=0.0367) in the NaLiCdS 2 structure-type. - Graphical abstract: Structure of LiNaMnS 2 . Li and Mn are statistically distributed in edge-shared tetrahedral environments linked into infinite planes. Sodium ions occupy interlayer sites

Physiology of free radicals

Directory of Open Access Journals (Sweden)

Stevanović Jelka

2011-01-01

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

Missing Peroxy Radical Sources Within a Rural Forest Canopy

Science.gov (United States)

Wolfe, G. M.; Cantrell, C.; Kim, S.; Mauldin, R. L., III; Karl, T.; Harley, P.; Turnipseed, A.; Zheng, W.; Flocke, F.; Apel, E. C.;

Effects of aqueous extract of Hibiscus sabdariffa on renal Na(+)-K(+)-ATPase and Ca(2+)-Mg(2+)-ATPase activities in Wistar rats.

Science.gov (United States)

Olatunji, Lawrence A; Usman, Taofeek O; Adebayo, Joseph O; Olatunji, Victoria A

2012-09-01

To investigate the effects of oral administration of aqueous extract of Hibiscus sabdariffa on renal Na(+)-K(+)-ATPase and Ca(2+)-Mg(2+)-ATPase activities in rats. The 25 and 50 mg/(kg·d) of aqueous extracts of H. sabdariffa were respectively given to rats in the experimental groups for 28 d, and rats in the control group received an appropriate volume of distilled water as vehicle. Na(+)-K(+)-ATPase and Ca(2+)-Mg(2+)-ATPase activities in the kidney were assayed by spectrophotometric method. Administrations of 25 and 50 mg/(kg·d) of aqueous extract of H. sabdariffa significantly decreased the Ca(2+)-Mg(2+)-ATPase activity in the kidney of rats (Psabdariffa may preserve the renal function despite a decreased renal Ca(2+)-Mg(2+)-ATPase activity.

Comparison between Two Bromine Containing Free Radical Initiators in PRESAGE®

Energy Technology Data Exchange (ETDEWEB)

Park, Hyeonsuk; Ryu, Dongmin; Ye, Sung-Joon [Seoul National University, Seoul (Korea, Republic of)

2016-10-15

PRESAGE® is an optically clear 3-D polyurethane dosimeter which contains a halogenated carbon as a free radical initiator and leucomalachite dye. The change of the optical density is known to be linear with respect to the absorbed dose and the sensitivity is related to the carbon–halogen bond dissociation energy of the free radical initiator. Although there are some studies regarding free radical initiators and dye materials, there’s a lack of reports about the effect of other elements like LMG solvent which can be added when there’s a difficulty mixing materials. Also, there are some studies about comparison between free radicals with different kind of halogen atoms but there’s a lack of studies of comparison between initiators with the same halogen atom. In this experiments, two kinds of halocarbon free radical initiator with the same halogen atom (bromine) as well as the effect of the LMG solvent were studied to use the dosimeter as a therapeutic purpose. Effective atomic numbers were also calculated. The initiators with the same halogen atom, CBr{sub 4} and C{sub 2}H{sub 2}Br{sub 4}, reacted totally differently. CBr{sub 4} was more sensitive to the radiation and emitted maximum 4 times more free radicals upon irradiation with no additional effective atomic number but the absorbance after irradiation was highly variable with time. For stable measurement, C{sub 2}H{sub 2}Br{sub 4} would be more appropriate as a free radical initiator.

Development of (2-bromo-1,1,2,2-tetrafluoroethyl)(phenyl)sulfane as tetrafluoroethyl-radical and tetrafluoroethylene-diradical synthons for additions to alkenes

Czech Academy of Sciences Publication Activity Database

Chernykh, Yana; Beier, Petr

2013-01-01

Roč. 156, December (2013), s. 307-313 ISSN 0022-1139 R&D Projects: GA ČR GAP207/11/0421 Institutional support: RVO:61388963 Keywords : radical addition * sulfide * tetrafluoroethyl * tetrafluoroethylene Subject RIV: CC - Organic Chemistry Impact factor: 1.952, year: 2013

Do all the European surgeons perform the same D2? The need of D2 audit in Europe.

Science.gov (United States)

Bencivenga, Maria; Verlato, Giuseppe; Mengardo, Valentina; Weindelmayer, Jacopo; Allum, William H

2018-06-04

Although D2 lymphadenectomy is the standard of care for radical intent surgical treatment of gastric cancer, the real compliance with D2 dissection in Europe is still unknown. The aim of the present study is to analyze the variation in lymph-node harvesting reported after D2 dissection in European series and to present a European project aiming at evaluating the real compliance with D2 lymphadenectomy. A PubMed search for papers using the key words "D2 lymphadenectomy" and "gastric cancer" from 2008 to 2017 was undertaken. Only studies by European authors in English language reporting the number of retrieved lymph nodes after D2 lymphadenectomy were included. The results of literature review were descriptively reported. The literature survey yielded 16 studies: 2 RCTs, 3 observational multicentre studies, and 11 observational monocentric studies. A large variability was found in the number of retrieved nodes, which, overall, was the lowest in the surgical series from Eastern Europe (16.6 and 19.9 in the Lithuanian and Hungarian series, respectively) and the highest in an Italian RCT. The within-study variability was also quite high, especially in multicentre RCTs and observational studies. Sample size tended to have a larger effect on the variability of lymph nodes retrieved than on its actual value. However, in both cases, the relation was not significant, due to the low number of studies considered. There is a large variability in the number of retrieved nodes after D2 dissection in European series. This reflects, at least partly, different approaches to D2 lymphadenectomy by European surgeons and may be responsible of the different outcomes observed in patients with gastric cancer across Europe. Therefore, there is the need to standardize the practice of D2 gastrectomy in Europe and to define possible variations of D2 procedures according to tumour's characteristics.

Muoniated acyl and thioacyl radicals

International Nuclear Information System (INIS)

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

2006-01-01

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

Muoniated acyl and thioacyl radicals

Energy Technology Data Exchange (ETDEWEB)

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

2006-03-31

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

Neutralization of Na2PO4: Reaction between Na3PO4 and CaCL2

International Nuclear Information System (INIS)

Xia Shenglan; Wang Luning

1990-01-01

The results of reaction Na 3 PO 4 with CaCl 2 in water at ambient and higher temperature are described. The reaction rate of Na 3 PO 4 with CaCl 2 is slow at ambient temperature and the reaction is complete at 260 deg C after 2 h. The products are Ca(OH) 2 and Ca 5 (PO 4 ) 3 (OH). The quantity of them is dependent upon the quanity of Na 3 PO 4 and CaCl 2 contained in water, all of them control pH of water

Formation of nitric oxide in an industrial burner measured by 2-D laser induced fluorescence

Energy Technology Data Exchange (ETDEWEB)

Arnold, A; Bombach, R; Kaeppeli, B [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

1997-06-01

We have performed two-dimensional Laser Induced Fluorescence (2-D LIF) measurements of nitric oxide and hydroxyl radical distributions in an industrial burner at atmospheric pressure. The relative 2-D LIF data of NO were set to an absolute scale by calibration with probe sampling combined with gas analysis. (author) 3 figs., 7 refs.

Deixando o preconceito de lado e entendendo o Behaviorismo Radical

Directory of Open Access Journals (Sweden)

Rodrigo Pinto Guimarães

Full Text Available O Behaviorismo Radical de Skinner é muitas vezes criticado de forma indevida e até preconceituosa. Muitas destas críticas, na verdade, são críticas da psicologia de Watson e não do Behaviorismo Radical. O entendimento das diferenças entre os modos idealista e materialista de pensar ajuda a esclarecer a maneira de estudar e compreender o comportamento para o Behaviorismo Radical, bem como a sua posição anti-mentalista. O estudo da história da evolução do Behaviorismo é necessário para possibilitar o entendimento das diferenças entre o Behaviorismo Metodológico de Watson e o Behaviorismo Radical de Skinner, bem como das suas respectivas contribuições para a psicologia.

Oncological outcomes of laparoscopic radical nephrectomy for renal cancer Resultados oncológicos da nefrectomia radical laparoscópica no tratamento do carcinoma renal

Directory of Open Access Journals (Sweden)

Jose R. Colombo Jr.

2007-01-01

Full Text Available PURPOSE: To report the 5-year oncological outcomes of patients undergoing laparoscopic radical nephrectomy for renal cancer compared to a cohort of patients undergoing open radical nephrectomy. METHODS: We retrospectively analyzed the data of 88 patients undergoing radical nephrectomy for renal cell carcinoma prior to January 2000. Of these, 45 patients underwent laparoscopic radical nephrectomy, and 43 patients underwent open radical nephrectomy. Inclusion criteria comprised clinically organ-confined tumors of 15 cm or less in size without concomitant lymphadenopathy or vena cava thrombus. Oncological follow-up data were obtained from charts, radiological reports, and phone calls to patients or their families, and were calculated from the date of surgery to the date of last appointment with physician or date of death. RESULTS: All laparoscopic procedures were completed without open conversion. On comparing the laparoscopic radical nephrectomy and open radical nephrectomy groups, mean tumor size was 5. 8 vs 6.2 cm (P = . 44, mean blood loss was 183 vs 461 mL (P = . 004, and mean operative time was 2.8 vs 3.7 hrs (P OBJETIVO: Relatar os resultados oncológicos após 5 anos de seguimento em pacientes submetidos a nefrectomia radical laparoscópica para tratamento do câncer renal, comparando esses com os resultados obtidos com um grupo de pacientes submetidos a nefrectomia radical aberta. MÉTODOS: Foram analisadas retrospectivamente as informações obtidas de 88 pacientes submetidos a nefrectomia radical para o tratamento do carcinoma renal realizadas previamente a Janeiro de 2000. Destes pacientes, 45 foram tratados com nefrectomia radical laparoscópica e 43 com nefrectomia radical aberta. Foram incluídos pacientes com tumores localizados com tamanho máximo de 15 cm, sem adenopatia ou sinal de envolvimento de veia renal na avaliação radiologica pré-operatória. As informações sobre o seguimento dos pacientes foram obtidas a partir de

Histidine, lysine, and arginine radical cations: isomer control via the choice of auxiliary ligand (L) in the dissociation of [CuII(L)amino acid]*2+ complexes.

Science.gov (United States)

Ke, Yuyong; Zhao, Junfang; Verkerk, Udo H; Hopkinson, Alan C; Siu, K W Michael

2007-12-27

Histidine, lysine, and arginine radical cations have been generated through collision-induced dissociation (CID) of complexes [CuII(auxiliary ligand)namino acid]*2+, using tri-, bi-, as well as monodentate auxiliary ligands. On the basis of the observed CID products, the existence of two isomeric amino-acid populations is postulated. The Type 1 radical cations of histidine and lysine, stable on the mass spectrometer time scale, were found to lose water, followed by the loss of carbon monoxide under more energetic CID conditions. The arginine Type 1 radical cation behaved differently, losing dehydroalanine. The Type 2 radical cations were metastable and easily fragmented by the loss of carbon dioxide, effectively preventing direct observation. Type 1 radical cations are proposed to result from neutral (canonical) amino-acid coordination, whereas Type 2 radical cations are from zwitterionic amino-acid coordination to copper in the complex. The ratio of Type 1/Type 2 ions was found to be dependent on the auxiliary ligand, providing a method of controlling which radical cation would be formed primarily. Density functional calculations at B3LYP/6-311++G(d,p) have been used to determine the relative energies of five His*+ isomers. Barriers against interconversion between the isomers and against fragmentation have been calculated, giving insight as to why the Type 1 ions are stable, while only fragmentation products of the Type 2 ions are observable under CID conditions.

A neural network potential energy surface for the NaH2 system and dynamics studies on the H(2S) + NaH(X1Σ+) → Na(2S) + H2(X1Σg+) reaction.

Science.gov (United States)

Wang, Shufen; Yuan, Jiuchuang; Li, Huixing; Chen, Maodu

2017-08-02

In order to study the dynamics of the reaction H( 2 S) + NaH(X 1 Σ + ) → Na( 2 S) + H 2 (X 1 Σ g + ), a new potential energy surface (PES) for the ground state of the NaH 2 system is constructed based on 35 730 ab initio energy points. Using basis sets of quadruple zeta quality, multireference configuration interaction calculations with Davidson correction were carried out to obtain the ab initio energy points. The neural network method is used to fit the PES, and the root mean square error is very small (0.00639 eV). The bond lengths, dissociation energies, zero-point energies and spectroscopic constants of H 2 (X 1 Σ g + ) and NaH(X 1 Σ + ) obtained on the new NaH 2 PES are in good agreement with the experiment data. On the new PES, the reactant coordinate-based time-dependent wave packet method is applied to study the reaction dynamics of H( 2 S) + NaH(X 1 Σ + ) → Na( 2 S) + H 2 (X 1 Σ g + ), and the reaction probabilities, integral cross-sections (ICSs) and differential cross-sections (DCSs) are obtained. There is no threshold in the reaction due to the absence of an energy barrier on the minimum energy path. When the collision energy increases, the ICSs decrease from a high value at low collision energy. The DCS results show that the angular distribution of the product molecules tends to the forward direction. Compared with the LiH 2 system, the NaH 2 system has a larger mass and the PES has a larger well at the H-NaH configuration, which leads to a higher ICS value in the H( 2 S) + NaH(X 1 Σ + ) → Na( 2 S) + H 2 (X 1 Σ g + ) reaction. Because the H( 2 S) + NaH(X 1 Σ + ) → Na( 2 S) + H 2 (X 1 Σ g + ) reaction releases more energy, the product molecules can be excited to a higher vibrational state.

Interaction between Na+/K+-pump and Na+/Ca2+-exchanger modulates intercellular communication.

Science.gov (United States)

Matchkov, Vladimir V; Gustafsson, Helena; Rahman, Awahan; Briggs Boedtkjer, Donna M; Gorintin, Sarah; Hansen, Anne Kirstine; Bouzinova, Elena V; Praetorius, Helle A; Aalkjaer, Christian; Nilsson, Holger

2007-04-13

Ouabain, a specific inhibitor of the Na(+)/K(+)-pump, has previously been shown to interfere with intercellular communication. Here we test the hypothesis that the communication between vascular smooth muscle cells is regulated through an interaction between the Na(+)/K(+)-pump and the Na(+)/Ca(2+)-exchanger leading to an increase in the intracellular calcium concentration ([Ca(2+)](i)) in discrete areas near the plasma membrane. [Ca(2+)](i) in smooth muscle cells was imaged in cultured rat aortic smooth muscle cell pairs (A7r5) and in rat mesenteric small artery segments simultaneously with force. In A7r5 coupling between cells was estimated by measuring membrane capacitance. Smooth muscle cells were uncoupled when the Na(+)/K(+)-pump was inhibited either by a low concentration of ouabain, which also caused a localized increase of [Ca(2+)](i) near the membrane, or by ATP depletion. Reduction of Na(+)/K(+)-pump activity by removal of extracellular potassium ([K(+)](o)) also uncoupled cells, but only after inhibition of K(ATP) channels. Inhibition of the Na(+)/Ca(2+)-exchange activity by SEA0400 or by a reduction of the equilibrium potential (making it more negative) also uncoupled the cells. Depletion of intracellular Na(+) and clamping of [Ca(2+)](i) at low concentrations prevented the uncoupling. The experiments suggest that the Na(+)/K(+)-pump may affect gap junction conductivity via localized changes in [Ca(2+)](i) through modulation of Na(+)/Ca(2+)-exchanger activity.

Moderate and Radical Islam

National Research Council Canada - National Science Library

Rabasa, Angel

2005-01-01

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

Isolation and Characterization of the 2,2'-Azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) Radical Cation-Scavenging Reaction Products of Arbutin.

Science.gov (United States)

Tai, Akihiro; Ohno, Asako; Ito, Hideyuki

2016-09-28

Arbutin, a glucoside of hydroquinone, has shown strong 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation-scavenging activity, especially in reaction stoichiometry. This study investigated the reaction mechanism of arbutin against ABTS radical cation that caused high stoichiometry of arbutin in an ABTS radical cation-scavenging assay. HPLC analysis of the reaction mixture of arbutin and ABTS radical cation indicated the existence of two reaction products. The two reaction products were purified and identified to be a covalent adduct of arbutin with an ABTS degradation fragment and 3-ethyl-6-sulfonate benzothiazolone. A time-course study of the radical-scavenging reactions of arbutin and the two reaction products suggested that one molecule of arbutin scavenges three ABTS radical cation molecules to generate an arbutin-ABTS fragment adduct as a final reaction product. The results suggest that one molecule of arbutin reduced two ABTS radical cation molecules to ABTS and then cleaved the third ABTS radical cation molecule to generate two products, an arbutin-ABTS fragment adduct and 3-ethyl-6-sulfonate benzothiazolone.

The preparation and graphene surface coating NaTi_2(PO_4)_3 as cathode material for lithium ion batteries

International Nuclear Information System (INIS)

Li, Na; Wang, Yanping; Rao, Richuan; Dong, Xiongzi; Zhang, Xianwen; Zhu, Sane

2017-01-01

Graphical abstract: The NaTi_2(PO_4)_3/graphene composite is used directly as cathode electrode material for lithium-ion battery by using metal lithium as an anode electrode. Meanwhile, the electrochemical properties of the composite in this system is firstly studied in detail. The NaTi_2(PO_4)_3/graphene composite exhibits the better rate and cyclic performance than NaTi_2(PO_4)_3, which is ascribed to its stable 3-D framework and the enhanced electronic conduction resulting from the graphene sheets surface modification. - Highlights: • The graphene coated NaTi_2(PO_4)_3 was prepared by a simple sol-gel method followed by calcination. • The electrochemical properties of the NaTi_2(PO_4)_3/graphene composite was firstly studied in detail when used as cathode electrode material for lithium-ion batteries. • The electrochemical reaction mechanism of NaTi_2(PO_4)_3/graphene composite was investigated by ex situ XRD. - Abstract: The graphene coated NaTi_2(PO_4)_3 has been fabricated via a simple sol-gel process followed by calcination. The NaTi_2(PO_4)_3/graphene (NTP/G) composite is used directly as cathode electrode material for lithium-ion battery and the electrochemical properties of the composite in this system is firstly studied in detail. In the charge-discharge process, two Li"+ can occupy octahedral M (2) site and be reversibly intercalated into the 3D framework of NTP through the ion conduction channel where almost all of Na"+ are immobilized to sustain the framework. At 5C rate, the capacity retention of the NTP/G composite after 800 cycles is still up to 82.7%. The superior electrochemical properties of NTP/G is ascribed to its stable 3-D framework and the enhanced electronic conduction resulting from the graphene sheets surface modification.

Hearing Status after Radical Mastoidectomy without Tympanoplasty.

Science.gov (United States)

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

2017-12-01

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

A novel process for ultrasound-induced radical polymerization in CO2-expanded fluids

NARCIS (Netherlands)

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

2005-01-01

A strong viscosity increase upon polymerization hinders cavitation and subsequent radical formation during an ultrasound-induced bulk polymerization. In this work, ultrasound-induced radical polymerizations of methyl methacrylate (MMA) have been performed in CO2-expanded MMA in order to reduce the

Free radical scavenging and COX-2 inhibition by simple colon metabolites of polyphenols: A theoretical approach.

Science.gov (United States)

Amić, Ana; Marković, Zoran; Marković, Jasmina M Dimitrić; Jeremić, Svetlana; Lučić, Bono; Amić, Dragan

2016-12-01

Free radical scavenging and inhibitory potency against cyclooxygenase-2 (COX-2) by two abundant colon metabolites of polyphenols, i.e., 3-hydroxyphenylacetic acid (3-HPAA) and 4-hydroxyphenylpropionic acid (4-HPPA) were theoretically studied. Different free radical scavenging mechanisms are investigated in water and pentyl ethanoate as a solvent. By considering electronic properties of scavenged free radicals, hydrogen atom transfer (HAT) and sequential proton loss electron transfer (SPLET) mechanisms are found to be thermodynamically probable and competitive processes in both media. The Gibbs free energy change for reaction of inactivation of free radicals indicates 3-HPAA and 4-HPPA as potent scavengers. Their reactivity toward free radicals was predicted to decrease as follows: hydroxyl>alkoxyls>phenoxyl≈peroxyls>superoxide. Shown free radical scavenging potency of 3-HPAA and 4-HPPA along with their high μM concentration produced by microbial colon degradation of polyphenols could enable at least in situ inactivation of free radicals. Docking analysis with structural forms of 3-HPAA and 4-HPPA indicates dianionic ligands as potent inhibitors of COX-2, an inducible enzyme involved in colon carcinogenesis. Obtained results suggest that suppressing levels of free radicals and COX-2 could be achieved by 3-HPAA and 4-HPPA indicating that these compounds may contribute to reduced risk of colon cancer development. Copyright © 2016 Elsevier Ltd. All rights reserved.

Photolysis and oxidation of azidophenyl-substituted radicals: delocalization in heteroatom-based radicals.

Science.gov (United States)

Serwinski, Paul R; Esat, Burak; Lahti, Paul M; Liao, Yi; Walton, Richard; Lan, Jiang

2004-08-06

2-(4-Azidophenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl (14), 2-(4-azidophenyl)benzimidazole-1-oxide-3-oxyl (16), 2-(4-azidophenyl)-1,2,6-triphenylverdazyl (19), 2-(3-azidophenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl (21), and (3-azidophenyl)-N-tert-butyl-N-aminoxyl (25) were photolyzed in frozen solution to give S = 3/2 state ESR spectra of the corresponding nitrenophenyl radicals with the following zero-field splitting parameters: |D/hc| = 0.277 cm(-1), |E/hc| ions were unsuccessful: Cu(ClO4)2 x 6H2O instead oxidized them to the corresponding diamagnetic nitrosonium perchlorate salts. Copyright 2004 American Chemical Society

Ionic liquid-assisted hydrothermal synthesis of dendrite-like NaY(MoO{sub 4}){sub 2}:Tb{sup 3+} phosphor

Energy Technology Data Exchange (ETDEWEB)

Tian Yue [Department of Physics, Dalian Maritime University, Dalian, Liaoning 116026 (China); College of Life Science, Dalian Nationalities University, Dalian, Liaoning 116600 (China); Chen Baojiu, E-mail: chenmbj@sohu.com [Department of Physics, Dalian Maritime University, Dalian, Liaoning 116026 (China); Tian Bining [Department of Physics, Dalian Maritime University, Dalian, Liaoning 116026 (China); College of Life Science, Dalian Nationalities University, Dalian, Liaoning 116600 (China); Sun Jiashi; Li Xiangping; Zhang Jinsu; Cheng Lihong; Zhong Haiyang; Zhong Hua [Department of Physics, Dalian Maritime University, Dalian, Liaoning 116026 (China); Meng Qingyu [School of Physics and Electronic Engineering, Harbin Normal University, Harbin 150025 (China); Hua Ruinian, E-mail: rnhua@dlnu.edu.cn [College of Life Science, Dalian Nationalities University, Dalian, Liaoning 116600 (China)

2012-07-01

Micro-sized NaY(MoO{sub 4}){sub 2}:Tb{sup 3+} phosphors with dendritic morphology was synthesized by a ionic liquid-assisted hydrothermal process. X-ray diffraction (XRD) indicated that the as-prepared product is pure tetragonal phase of NaY(MoO{sub 4}){sub 2}. Field emission scanning electron microscopy (FE-SEM) images showed that the as-prepared NaY(MoO{sub 4}){sub 2}:Tb{sup 3+} phosphors have dendritic morphology. The photoluminescent (PL) spectra displayed that the as-prepared NaY(MoO{sub 4}){sub 2}:Tb{sup 3+} phosphors show a stronger green emission with main emission wavelength 545 nm corresponding to the {sup 5}D{sub 4}{yields}{sup 7}F{sub 5} transition of Tb{sup 3+} ion, and the optimal Tb{sup 3+} doping concentration for obtaining maximum emission intensity was confirmed to be 10 mol%. Based on Van Uitert's and Dexter's models the electric dipole-dipole (D-D) interaction was confirmed to be responsible for the concentration quenching of {sup 5}D{sub 4} fluorescence of Tb{sup 3+} in the NaY(MoO{sub 4}){sub 2}:Tb{sup 3+} phosphors. The intrinsic radiative transition lifetime of {sup 5}D{sub 4} level is found to be 0.703 ms.

Aktualne poglądy na temat roli witaminy D w patogenezie stwardnienia rozsianego

Directory of Open Access Journals (Sweden)

Magdalena Antczak

2013-04-01

Full Text Available Witamina D jest powszechnie znana ze swojej roli w gospodarce wapniowo-fosforanowej, ale wzrastająca ilość danych wskazuje na jej działania plejotropowe. Zaobserwowano pozytywną korelację między niedoborem witaminy D a występowaniem chorób autoimmunologicznych, w tym stwardnienia rozsianego, reumatoidalnego zapalenia stawów, tocznia rumieniowatego układowego itp. Receptory witaminy D są obecne w szeregu tkanek i narządów, w tym w kościach, mięśniach, narządach rozrodczych, sercu, mózgu oraz w obrębie układu odporno- ściowego. Coraz lepiej poznawane działanie immunomodulujące witaminy D obejmuje wpływ zarówno na mechanizmy odporności wrodzonej, jak i adaptacyjnej, poprzez hamowanie proliferacji i cytotoksyczności limfocytów T, promowanie różnicowania limfocytów T regulatorowych oraz modulowanie działania makrofagów i komórek dendrytycznych. Stwardnienie rozsiane (łac. sclerosis multiplex, SM jest chorobą autoimmunologiczną ośrodkowego układu nerwowego spowodowaną przez skomplikowane i w dużej mierze nieznane interakcje między predyspozycjami genetycznymi i czynnikami środowiskowymi. Badania epidemiologiczne wskazują, że ekspozycja na promieniowanie słoneczne i związany z nią poziom witaminy D są ważnymi czynnikami mogącymi wyjaśniać zróżnicowanie geograficzne częstości zachorowań na SM. Wyniki niektórych wstępnych obserwacji sugerują, że suplementacja witaminy D może zmniejszać ryzyko zachorowania na SM oraz modulować przebieg choroby i zmniejszać częstość jej nawrotów u pacjentów z rzutowo-remisyjną postacią SM. Wyniki te skłoniły do podjęcia prób włączenia witaminy D jako składnika wspomagającego terapię SM. Obserwacje te wymagają dalszego potwierdzenia i badań klinicznych.

New alkali metal diphosphates how materials to preserve the security of the environment: CsNaCu(P2O7), Rb2Cu(P2O7) and CsNaCo(P2O7) synthesis and crystal structure determination

Science.gov (United States)

Chernyatieva, Anastasiya; Filatova, Alyona; Spiridonova, Dariya; Krivovichev, Sergey

2013-04-01

In this work we describe preliminary results of the synthesis and of a crystal-chemical study of synthetic phosphates with transition metals. Due to the increasing requirements for environmental safety specialists from various industries, we are searching for sustainable forms of immobilization of hazardous waste during storage. We are also developing a component-based waste for new materials. In our continued exploratory synthesis of compounds containing transition-metals, we were able to produce the new diphosphate phases CsNaCu(P2O7), Rb2Cu(P2O7) and CsNaCo(P2O7). A crystal chemical study has allowed us to identify new phosphates. Crystals of CsNaCu(P2O7) (Phase 1) is orthorhombic, crystallizes in space group Pmn21, with a = 5.147(8), b = 15.126(2), c = 9.717(2) Å, V = 756.20 Å3, R1 = 0.066 and Rb2Cu(P2O7) (Phase 2) is orthorhombic as well, crystallizes in space group Pmcn, with a = 5.183(8), b = 10.096(1), c = 15.146(3) Å, V = 793.55 Å3, R1 = 0.063, they have been obtained by high-temperature reaction of RbNO3, CsNO3, Cu(NO3)2, NaOH and (NH4)4P2O7. Synthetic crystals of the phosphate of copper and rubidium were studied in detail by us on the structures of Rb2Cu(P2O7) and Rb2Cu3(P2O7)2 - new alkali metal copper diphosphates (CHERNYATIEVA et al., 2008). Here we report the synthesis, the structure and the properties of the title compounds and we compare these phases with the previously discovered K2CuP2O7 (ELMAADI et al., 1995) and CsNaMnP2O7 (HUANG et al., 1998). These structures crystallize in other space groups, although their structures are also based on 2-D layers, formed by P2O7 groups combined with polyhedra of the transition metals (CHERNYATIEVA et al., 2012). A crystal chemical study has allowed us to identify even new diphosphates CsNaCu(P2O7) (Phase 3). Crystals of CsNaCoP2O7 is monoclinic, space group P 21/n, with a = 7,424(2), b = 7,648(1), c = 12,931(3)Å, β = 90,71(2)° , V = 734.2(3) Å3 and R1 = 0.060. The structure is based framework of Co

Charged particle multiplicities at {radical}(s)=0.9, 2.36 and 7.0 TeV with the CMS detector at LHC

Energy Technology Data Exchange (ETDEWEB)

Rougny, Romain [Universiteit Antwerpen, Gratiekapelstraat 10, BE-2000 Antwerpen (Belgium); De Wolf, E.A.; Janssen, X.; Mucibello, L.; Van Remortel, N.; Lee, Y.J.; Busza, Wit

2010-07-01

The charged particle multiplicity, n, is an essential observable in hadron collisions. It is the result of the counting of all charged particles produced by the primary proton-proton interaction. In particular, the events collected by minimum bias triggers contain soft interactions and produce mostly particles with low transverse momenta. The shape of the charged particle multiplicity spectrum is sensitive to the particle production mechanism of these soft interactions which are described by non-perturbative models, inspired by QCD. The correlations between produced hadrons are reflected in the shape of the multiplicity spectrum, while the mean multiplicity increases with the center of mass energy of the collision. We present the measurement of the charged particle multiplicity distributions, 1/s d{sigma}/dn, in increasing sub-domains of pseudorapidity and transverse momentum acceptance, for non single diffractive interactions. The data are further corrected for the trigger and event selection efficiency and the effects of tracking inefficiency and secondary tracks originating from the decay of long lived particles and products of interaction with the beam pipe and the detector material. This measurement is based on minimum bias data collected by the CMS detector at {radical}(s) = 0.9, 2.36 and 7 TeV. The data were collected during the LHC commissioning run in 2009 and at the beginning of 2010. (authors)

Role of O radical on the formation of O{sub 2} gas plasma; O{sub 2} purazuma ni okeru O rajikaru no yakuwari

Energy Technology Data Exchange (ETDEWEB)

Matsui, I. [Toshiba Reasearch and Development Ceter, Tokyo (Japan). Mechanical Systems Laboratory

2000-11-10

The effect of plasma formed gas on the plasma structure is investigated using a self consistent continuous fluid plasma model, which assumes that the local field approximation was attained in the RF plasma. The swarm parameter was obtained by Boltzmann analysis for O{sub 2} gas which contains various amounts of O radicals. Positive ion density, negative ion density, and electron density in the O{sub 2} RF plasma including O radical generation were calculated by self-consistent one dimensional continuous fluid plasma model. The calculation results show the dominant positive charged particle became O{sup +} from O{sub 2}{sup +} with increasing amount of O radical in O{sub 2}. The plasma positive densities are not greatly affected if O radical content did not exceed 1 % of O{sub 2}. It was concluded that O{sub 2} plasma structure can be evaluated by source gas plasma calculation neglecting radical formation, since O radical formation in the O{sub 2} plasma is estimated as less than 0.2 % of O{sub 2}. (author)

Possíveis relações entre o contexto histórico e a recepção do behaviorismo radical

Directory of Open Access Journals (Sweden)

Robson Nascimento da Cruz

Full Text Available O artigo discute a recepção do behaviorismo radical, em especial, na década de 70, e busca relacionar a polêmica em torno de algumas noções skinnerianas acerca da liberdade e da dignidade divulgadas no livro Para Além da Liberdade e Dignidade. Essa discussão foi orientada por três conjuntos de questões: a a incompatibilidade entre alguns aspectos históricos e a definição behaviorista radical de liberdade e dignidade; b os problemas em identificar o behaviorismo radical como uma abordagem solidária com os pressupostos de uma ideologia liberalista; c a linguagem utilizada por Skinner como fonte de problemas. Por fim, são discutidos as limitações e os problemas envolvidos em tentativas de esclarecimentos de possíveis mal-entendidos acerca do behaviorismo radical. Ao mesmo tempo, demonstra-se que a recepção do behaviorismo radical é perpassada por aspectos além daqueles relacionados à validade interna do sistema explicativo skinneriano, e que discordâncias acerca dessa abordagem nem sempre podem ser explicadas como desconhecimento e equívocos sobre a mesma.

Synthesis and visible-light-driven photocatalytic activity of p–n heterojunction Ag{sub 2}O/NaTaO{sub 3} nanocubes

Energy Technology Data Exchange (ETDEWEB)

Yang, Songbo [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Xu, Dongbo [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); School of Energy and Power Engineering, Jiangsu University, Zhenjiang 212013 (China); Chen, Biyi; Luo, Bifu [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Yan, Xu [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); School of Energy and Power Engineering, Jiangsu University, Zhenjiang 212013 (China); Xiao, Lisong, E-mail: xiaolisong123@sina.com [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Shi, Weidong, E-mail: swd1978@ujs.edu.cn [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China)

2016-10-15

Highlights: • We firstly report a facile way to prepare the visible-light-driven Ag{sub 2}O/NaTaO{sub 3}p–n heterojunction by chemical precipitation method. • The Ag{sub 2}O/NaTaO{sub 3} heterojunction shows the highest photocatalytic activity than the pure NaTaO{sub 3} and Ag{sub 2}O nanoparticles under visible light. • The enhancement of the heterojunction photocatalytic activity was discussed and the photocatalytic mechanism was tested in our paper. • In summary, we think that the Ag{sub 2}O/NaTaO{sub 3} heterojunction with the strong visible light absorption and efficient photocatalytic activity have been extended application in photocatalysis for organic dyes pollutants degradation and purification of water. - Abstract: The constructing of p–n heterojunction photocatalytic system has received much attention in environmental purification and hydrogen generation from water. In this study, an efficient visible-light-driven p–n heterojunction Ag{sub 2}O/NaTaO{sub 3} was successfully prepared by chemical precipitation method at room temperature. It showed an enhanced photocatalytic activity for the degradation of rhodamine B (RhB) under visible-light irradiation, much higher than those of either individual Ag{sub 2}O or NaTaO{sub 3}. The reactive species scavenger results indicated the superoxide anion radicals (·O{sup 2−}) played key roles in RhB decoloration. From the experimental results and the relative band gap position of these semiconductors, a detailed possible photocatalytic mechanism of the Ag{sub 2}O/NaTaO{sub 3} heterojunction under visible light was proposed. The enhancement of the photocatalytic activity was attributed to the interfacial electronic interaction between NaTaO{sub 3} and Ag{sub 2}O and the high migration efficiency of photogenerated carriers.

Study on the source of optical activity: Pt. 6. ESR spectroscopy on the asymmetrical radical yields in 90Sr-90Y β irradiated D-and L-alanine

International Nuclear Information System (INIS)

Wang Wenqing; Zhao Jian; Ding Xiang

1993-01-01

Free radical formation in 90 Sr- 90 Y β irradiated D- and L-alanine is studied by ESR spectroscopy. To calibrate the probable differences in the size of ESR tubes, the different densities of alanine and the incidental different impurities, samples are firstly irradiated with 60 Co γ rays. Then the D- and L- alanine samples are irradiated with 90 Sr- 90 Y source at 77 K. Soon after irradiation, ESR measurement is performed on each sample. The average ratio H β+γ /H γ of D- alanine is 0.147 higher than that of L- alanine, indicating that more free radicals are induced in D- alanine by β irradiation. Irradiation at 77 K is capable of diminishing the effect of thermal movement on the polarization of β electrons and freezing the free radical formation. The experiments show the stereoselective interaction of β electrons with D- and L- amino acids, and so supports the Vester-ulbricht hypothesis

Bulk crystal growth and electronic characterization of the 3D Dirac semimetal Na3Bi

Directory of Open Access Journals (Sweden)

Satya K. Kushwaha

2015-04-01

Full Text Available High quality hexagon plate-like Na3Bi crystals with large (001 plane surfaces were grown from a molten Na flux. The freshly cleaved crystals were analyzed by low temperature scanning tunneling microscopy and angle-resolved photoemission spectroscopy, allowing for the characterization of the three-dimensional (3D Dirac semimetal (TDS behavior and the observation of the topological surface states. Landau levels were observed, and the energy-momentum relations exhibited a linear dispersion relationship, characteristic of the 3D TDS nature of Na3Bi. In transport measurements on Na3Bi crystals, the linear magnetoresistance and Shubnikov-de Haas quantum oscillations are observed for the first time.

Electronic spectrum of 9-methylanthracenium radical cation

Energy Technology Data Exchange (ETDEWEB)

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

2016-04-21

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

2.5D Animacija

OpenAIRE

Rođak, Bruno

2016-01-01

Tema ovog rada je 2.5D animacija i primjena te tehnike animiranja pri izradi kratkometražnog animiranog filma. Kroz pisani dio ovog rada pokrivaju se svi koraci uključeni u izradu animiranog filma. Obrada se pažnja na korake tog procesa raširene kroz pretprodukciju, produkciju i postprodukciju. Realizacija praktičnog djela rada je napravljena pomodu programa Adobe After Effects, Adobe Photoshop-a, Blendera i Adobe Premiera Pro. Realizacija kroz navedene programe de bit detaljno opisana korak ...

Radiation-induced degradation of D-fructose in aerated condition

International Nuclear Information System (INIS)

Kito, Yukio; Kawakishi, Shunro; Namiki, Mitsuo

1981-01-01

Gamma-radiolysis of fructose in aqueous solution under aerated conditions formed various oxidized products, such as dicarbonyl hexoses, lower molecular aldoses and aldonic acids. Among these radiolytic products, D-arabinohexosulose (1, G = 2.2) and D-threo-2,5-hexodiulose (2, G = 1.5) were identified as major hexose derivatives, and D-threo-2,3-hexodiulose (3) and D-lyxo-hexos-5-ulose (4) as minor products. The radiolytic processes were found to be derived through fructose radicals, similarly to anaerobic radiolysis of fructose. The mechanism of radiolysis was proposed to be initiated by hydrogen abstraction with hydroxyl radical, followed by formation and degradation of fructose hydroperoxy radicals. (author)

Ultraviolet absorption spectra and kinetics of CH3S and CH2SH radicals

DEFF Research Database (Denmark)

Anastasi, C.; Broomfield, M.; Nielsen, O.J.

1991-01-01

The ultraviolet absorption spectra of CH3S and CH2SH radicals have been measured between 215 and 380 nm using the pulse-radiolysis/kinetic-absorption method. One absorption band between 250 and 300 nm and one around 215 nm have been tentatively assigned to the CH2SH and CH3S radicals, respectively....... This spectrum has been used to measure the self-reaction rates of these radicals. Rate constants of 4 x 10(-11) and 7 x 10(-11) cm3 molecule-1 s-1 have been measured at 298 K for CH3S and CH2SH recombination, respectively. The possible reaction pathways are discussed....

A P2-Type Layered Superionic Conductor Ga-Doped Na2 Zn2 TeO6 for All-Solid-State Sodium-Ion Batteries.

Science.gov (United States)

Li, Yuyu; Deng, Zhi; Peng, Jian; Chen, Enyi; Yu, Yao; Li, Xiang; Luo, Jiahuan; Huang, Yangyang; Zhu, Jinlong; Fang, Chun; Li, Qing; Han, Jiantao; Huang, Yunhui

2018-01-24

Here, a P2-type layered Na 2 Zn 2 TeO 6 (NZTO) is reported with a high Na + ion conductivity ≈0.6×10 -3  S cm -1 at room temperature (RT), which is comparable to the currently best Na 1+n Zr 2 Si n P 3-n O 12 NASICON structure. As small amounts of Ga 3+ substitutes for Zn 2+ , more Na + vacancies are introduced in the interlayer gaps, which greatly reduces strong Na + -Na + coulomb interactions. Ga-substituted NZTO exhibits a superionic conductivity of ≈1.1×10 -3  S cm -1 at RT, and excellent phase and electrochemical stability. All solid-state batteries have been successfully assembled with a capacity of ≈70 mAh g -1 over 10 cycles with a rate of 0.2 C at 80 °C. 23 Na nuclear magnetic resonance (NMR) studies on powder samples show intra-grain (bulk) diffusion coefficients D NMR on the order of 12.35×10 -12  m 2  s -1 at 65 °C that corresponds to a conductivity σ NMR of 8.16×10 -3  S cm -1 , assuming the Nernst-Einstein equation, which thus suggests a new perspective of fast Na + ion conductor for advanced sodium ion batteries. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

In search of the X{sub 2}BO and X{sub 2}BS (X = H, F) free radicals: Ab initio studies of their spectroscopic signatures

Energy Technology Data Exchange (ETDEWEB)

Clouthier, Dennis J., E-mail: dclaser@uky.edu [Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055 (United States)

2014-12-28

The F{sub 2}BO free radical is a known, although little studied, species but similar X{sub 2}BY (X = H, D, F; Y = O, S) molecules are largely unknown. High level ab initio methods have been used to predict the molecular structures, vibrational frequencies (in cm{sup −1}), and relative energies of the ground and first two excited electronic states of these free radicals, as an aid to their eventual spectroscopic identification. The chosen theoretical methods and basis sets were tested on F{sub 2}BO and found to give good agreement with the known experimental quantities. In particular, complete basis set extrapolations of coupled-cluster single and doubles with perturbative triple excitations/aug-cc-pVXZ (X = 3, 4, 5) energies gave excellent electronic term values, due to small changes in geometry between states and the lack of significant multireference character in the wavefunctions. The radicals are found to have planar C{sub 2v} geometries in the X{sup ~2}B{sub 2} ground state, the low-lying A{sup ~2}B{sub 1} first excited state, and the higher B{sup ~2}A{sub 1} state. Some of these radicals have very small ground state dipole moments hindering microwave measurements. Infrared studies in matrices or in the gas phase may be possible although the fundamentals of H{sub 2}BO and H{sub 2}BS are quite weak. The most promising method of identifying these species in the gas phase appears to be absorption or laser-induced fluorescence spectroscopy through the allowed B{sup ~}-X{sup ~} transitions which occur in the visible-near UV region of the electromagnetic spectrum. The ab initio results have been used to calculate the Franck-Condon profiles of the absorption and emission spectra, and the rotational structure of the B{sup ~}-X{sup ~}0{sub 0}{sup 0} bands has been simulated. The calculated single vibronic level emission spectra provide a unique, readily recognizable fingerprint of each particular radical, facilitating the experimental identification of new X{sub 2}BY

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

DEFF Research Database (Denmark)

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

1999-01-01

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

Pulse radiolysis study on free radical scavenger edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one). 2: A comparative study on edaravone derivatives

International Nuclear Information System (INIS)

Hata, Kuniki; Katsumura, Yosuke; Lin, M.; Yamashita, Shinichi; Muroya, Yusa; Fu Haiying; Nakagawa, Hidehiko

2011-01-01

A comparative study using the pulse radiolysis technique was carried out to investigate transient absorption spectra and rate constants for the reactions of OH radical and N 3 radical with edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) and its four analogue compounds, 1,3-dimethyl-2-pyrazolin-5-one, 3-methyl-1-(pyridin-2-yl)-2-pyrazolin-5-one, 1-phenyl-3-trifluoromethyl-2-pyrazolin-5-one and 1-(4-chlorophenyl)-3-methyl-2-pyrazolin-5-one. The results showed that, unlike reaction mechanisms previously proposed, the phenyl group of edaravone played an important role in the reaction with OH radical and OH adducts to the phenyl group were formed. Quantum chemical calculations also strongly supported this attribution and suggested that the most favorable site for attacks by OH radical is the ortho position of the phenyl group. Moreover, the rate constants for the reactions of edaravone and its analogues towards OH radical and N 3 radical were about 8.0 x 10 9 , and 4.0 x 10 9 dm 3 mol -1 s -1 , respectively. Edaravone displayed higher reactivity compared to the others, in contrast to a previous report in which 3-methyl-1-(pyridin-2-yl)-2-pyrazolin-5-one showed the highest reactivity towards Hydroxyl radical OH. (author)

Načrtovanje vodnogospodarskih ureditev s programskim orodjem Autodesk CIVIL 3D

OpenAIRE

Lubej, Gorazd

2016-01-01

Diplomsko delo je sestavljeno iz samih osnov vodnogospodarskih ureditev ter primerjave načrtovanja s programskim orodjem AutoCAD 2015 z vmesnikom/vtičnikom Aquaterra in programskim orodjem Autodesk Civil 3D. Cilj je predstavitev dela oziroma postopka dela z obema programskima orodjema, da se dobi vpogled v potek dela z enim in drugim programom. Ugotovljeno je, da je za časovno omejeno pripravo načrtov (kratki rok izdelave načrta) primernejša uporaba programskega orodja AutoCAD 2015 z vmesniko...

Peroxy Radical Measurements during the IRRONIC Field Project by C2H6 - NO Chemical Amplification

Science.gov (United States)

Wood, E. C. D.; Kundu, S.; Deming, B.; Lew, M.; Stevens, P. S.; Sklaveniti, S.; Dusanter, S.

2015-12-01

We present measurements of total peroxy radicals (HO2 + RO2) during the Indiana Radical, Reactivity and Ozone Production Intercomparison (IRRONIC) field project in Bloomington, Indiana during July 2015. Peroxy radicals were measured by chemical amplification using ethane and nitric oxide in dual PFA reaction chambers, and the amplification product NO2 was quantified by cavity attenuated phase shift spectroscopy. On sunny days mid-day peroxy radical mixing ratios were typically between 20 and 70 ppt and were well correlated with "HO2*" measured by the Indiana University Laser-Induced Fluorescence with Fluorescence Assay by Gas Expansion (IU-FAGE) instrument. The ratio of total peroxy radicals (UMass) to the IU-FAGE HO2* measurements was greater than two. We also describe results from an informal intercomparison of the two instruments' calibration sources, which are based on acetone photolysis (UMass) and water photolysis (IU). In addition to sampling the IU calibration source in "amplification" mode, the UMass instrument also separately quantified the HO2 mixing ratio in the IU calibration gas by reaction with excess NO and subsequent quantification of the NO2 produced.

Enhancing Catalyzed Decomposition of Na2CO3 with Co2MnO x Nanowire-Decorated Carbon Fibers for Advanced Na-CO2 Batteries.

Science.gov (United States)

Fang, Cong; Luo, Jianmin; Jin, Chengbin; Yuan, Huadong; Sheng, Ouwei; Huang, Hui; Gan, Yongping; Xia, Yang; Liang, Chu; Zhang, Jun; Zhang, Wenkui; Tao, Xinyong

2018-05-23

The metal-CO 2 batteries, especially Na-CO 2 , batteries come into sight owing to their high energy density, ability for CO 2 capture, and the abundance of sodium resource. Besides the sluggish electrochemical reactions at the gas cathodes and the instability of the electrolyte at a high voltage, the final discharge product Na 2 CO 3 is a solid and poor conductor of electricity, which may cause the high overpotential and poor cycle performance for the Na-CO 2 batteries. The promotion of decomposition of Na 2 CO 3 should be an efficient strategy to enhance the electrochemical performance. Here, we design a facile Na 2 CO 3 activation experiment to screen the efficient cathode catalyst for the Na-CO 2 batteries. It is found that the Co 2 MnO x nanowire-decorated carbon fibers (CMO@CF) can promote the Na 2 CO 3 decomposition at the lowest voltage among all these metal oxide-decorated carbon fiber structures. After assembling the Na-CO 2 batteries, the electrodes based on CMO@CF show lower overpotential and better cycling performance compared with the electrodes based on pristine carbon fibers and other metal oxide-modified carbon fibers. We believe this catalyst screening method and the freestanding structure of the CMO@CF electrode may provide an important reference for the development of advanced Na-CO 2 batteries.

Suppression of Raman electron spin relaxation of radicals in crystals. Comparison of Cu2+ and free radical relaxation in triglycine sulfate and Tutton salt single crystals.

Science.gov (United States)

Hoffmann, S K; Goslar, J; Lijewski, S

2011-08-31

Electron spin-lattice relaxation was measured by the electron spin echo method in a broad temperature range above 4.2 K for Cu(2+) ions and free radicals produced by ionizing radiation in triglycine sulfate (TGS) and Tutton salt (NH4)(2)Zn(SO4)2 ⋅ 6H2O crystals. Localization of the paramagnetic centres in the crystal unit cells was determined from continuous wave electron paramagnetic resonance spectra. Various spin relaxation processes and mechanisms are outlined. Cu(2+) ions relax fast via two-phonon Raman processes in both crystals involving the whole phonon spectrum of the host lattice. This relaxation is slightly slower for TGS where Cu(2+) ions are in the interstitial position. The ordinary Raman processes do not contribute to the radical relaxation which relaxes via the local phonon mode. The local mode lies within the acoustic phonon band for radicals in TGS but within the optical phonon range in (NH4)(2)Zn(SO4)2 ⋅ 6H2O. In the latter the cross-relaxation was considered. A lack of phonons around the radical molecules suggested a local crystal amorphisation produced by x- or γ-rays.

The impact of UV irradiation on the radical initiating capacity of dissolved dyes

International Nuclear Information System (INIS)

Vig, A.; Czilik, M.; Rusznak, I.

2002-01-01

Complete text of publication follows. Kinetics of photodecomposition of three model dyes dissolved in isopropanol-water mixture has been determined after exposure to UV radiation in the range from 360 through 400 nm and from 220 through 400 nm, respectively. It has been disclosed earlier that photodecomposition of the dissolved dyes was decelerated initially by the presence of the dissolved oxygen in the system. The presence of a radical initiator, AIBN was indispensable for arriving at the decomposition of the irradiated dye solution in the range from 360 through 400 nm. The equation of W i D = [O 2 ]/τ D was used for the calculation of radical initiating rate of the irradiated dye molecule on the isopropanol (W i D (mol/l x s)), where [O 2 ] (mol/l) is the dissolved oxygen concentration in the system and τ D (s) is duration of the induction period of the photodestruction of the dissolved dye. The equation is valid only for photodecomposition which are not chain reaction. The photodegradation of dissolved dyes was also other then chain reaction, consequently the above equation could be applied in the study too. The average radical initiating rate of the dyes applied in this study was in the order of magnitude equal to that of AIBN. The number of cycles between the first radical formation and the last regeneration of the dye molecule could be calculated in bath systems (in the presence and absence of oxygen, respectively): K = W i D /W D , where K is the number of cycles, W D (mol/l x s) is the initial rate of the decomposition of the dissolved dyed. The number of cycles in the oxygen containing systems significantly exceeded those obtained in the oxygen systems because W D was markedly higher in the latter system than in the former one

The radical right ineurope, between slogans and voting behavior A direita radical na Europa, entre slogans e comportamento de voto

Directory of Open Access Journals (Sweden)

Nicolò Conti

2011-10-01

Full Text Available The article analyzes the radical right’s attitudes toward the EU focusing in particular on the level of congruence between the programmatic statements of their central offices and the voting behavior of their MEPs. It shows that although radical right parties are a source of opposition to the EU, within the EP they express their dissent by abiding by the rules of the game, voting with the opposition more than the other forces do, but also voting almost as often with the majority. The radical right’s MEPs engage in the legislative process and cooperate with parties on both sides of the political spectrum more than the Eurosceptic rhetoric and statements of their central offices lead the public to believe.O artigo analisa as atitudes da direita radical em relação à UE, focando-se, em particular, no nível de congruência entre as afirmações programáticas dos seus dirigentes e o comportamento de voto dos seus membros no parlamento europeu. Demonstra que apesar de os partidos radicais de direita constituírem um foco de oposição à UE, quando no parlamento europeu expressam o seu desacordo dentro das regras do jogo, votando com a oposição mais do que as outras forças, mas votando também com a maioria quase com igual regularidade. Os grupos parlamentares inserem-se no processo legislativo e são mais colaborantes com outros partidos de toda a gama ideológica do que a retórica e as afirmações dos dirigentes centrais fazem crer.

Kinetics and mechanisms of reactions of CF, CHF, and CF2 radicals

International Nuclear Information System (INIS)

Hsu, D.S.Y.; Umstead, M.E.; Lin, M.C.

1978-01-01

This chapter reviews briefly methods for the production of CF, CHF and CF 2 , and inmore detail, the reactions of these interesting and important radicals. Although a considerable, but not extensive, amount of work has been done on the reactions of CF 2 , little of the chemistry of CF and CHF is known. This chapter also includes the preliminary results of some experiments carried out in this Laboratory on the dynamics of some of the reactions involving these radicals. These results were largely arrived at through investigations of the degree of vibrational excitation of the HF and CO reaction products, determined by HF and CO laser emission and CO laser resonance absorption measurements. The coverage of this review is restricted to the gas phase chemistry of these radicals, and does not include their addition reactions to olefins

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

International Nuclear Information System (INIS)

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

1998-01-01

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

High-Capacity and Ultrafast Na-Ion Storage of a Self-Supported 3D Porous Antimony Persulfide-Graphene Foam Architecture.

Science.gov (United States)

Lu, Yanying; Zhang, Ning; Jiang, Shuang; Zhang, Yudong; Zhou, Meng; Tao, Zhanliang; Archer, Lynden A; Chen, Jun

2017-06-14

The key challenge for high-performance sodium-ion batteries is the exploitation of appropriate electrode materials with a long cycling stability and high rate capability. Here, we report Sb 2 S 5 nanoparticles (∼5 nm) uniformly encapsulated in three-dimensional (3D) porous graphene foam, which were fabricated by a facile hydrothermal coassembly strategy, as a high-performance anode material for sodium-ion batteries. The as-prepared composite can be directly used as electrodes without adding a binder or current collector, exhibiting outstanding electrochemical performance with a high reversible capacity (845 mA h g -1 at 0.1 A g -1 ), ultralong cycling life (91.6% capacity retention after 300 cycles at 0.2 A g -1 ), and exceptional rate capability (525 mA h g -1 at 10.0 A g -1 ). This is attributed to fast Na + ion diffusion from the ultrasmall nanoparticles and excellent electric transport between the active material and 3D porous graphene, which also provide an effective strategy for anchoring the nanoparticles. Experimental results show that the Sb 2 S 5 undergoes a reversible reaction of Sb 2 S 5 + 16Na ↔ 5Na 2 S + 2Na 3 Sb during sodiation/desodiation. Moreover, a full cell with Na 3 (VO 0.5 ) 2 (PO 4 ) 2 F 2 /C cathode and the as-prepared composite anode was assembled, displaying high output voltage (∼2.2 V) with a stable capacity of 828 mA h g -1 for anode material (with 100 cycles at 0.1 A g -1 ), showing the potential for practical application.