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Sample records for carbon 12 reactions

  1. Study of 16O(12C,α20Ne)α for the investigation of carbon-carbon fusion reaction via the Trojan Horse Method

    International Nuclear Information System (INIS)

    Rapisarda, G.G.; Spitaleri, C; Kiss, G.G.; La Cognata, M.; Pizzone, R.G.; Romano, S.; Tumino, A.; Bordeanu, C.; Nita, C.; Pantelica, D.; Petrascu, H.; Velisa, G.; Hons, Z.; Mrazek, J.; Szücs, T.; Trache, L.

    2016-01-01

    Carbon-carbon fusion reaction represents a nuclear process of great interest in astrophysics, since the carbon burning is connected with the third phase of massive stars (M > 8 M ☉ ) evolution. In spite of several experimental works, carbon-carbon cross section has been measured at energy still above the Gamow window moreover data at low energy present big uncertainty. In this paper we report the results about the study of the 16 O( 12 C,α 20 Ne)α reaction as a possible three-body process to investigate 12 C( 12 C,α) 20 Ne at astrophysical energy via Trojan Horse Method (THM). This study represents the first step of a program of experiments aimed to measure the 12 C+ 12 C cross section at astrophysical energy using the THM. (paper)

  2. Degradation mechanism of Direct Pink 12B treated by iron-carbon micro-electrolysis and Fenton reaction.

    Science.gov (United States)

    Wang, Xiquan; Gong, Xiaokang; Zhang, Qiuxia; Du, Haijuan

    2013-12-01

    The Direct Pink 12B dye was treated by iron-carbon micro-electrolysis (ICME) and Fenton oxidation. The degradation pathway of Direct Pink 12B dye was inferred by ultraviolet visible (UV-Vis), infrared absorption spectrum (IR) and high performance liquid chromatography-mass spectrometry (HPLC-MS). The major reason of decolorization was that the conjugate structure was disrupted in the iron-carbon micro-electrolysis (ICME) process. However, the dye was not degraded completely because benzene rings and naphthalene rings were not broken. In the Fenton oxidation process, the azo bond groups surrounded by higher electron cloud density were first attacked by hydroxyl radicals to decolorize the dye molecule. Finally benzene rings and naphthalene rings were mineralized to H2O and CO2 under the oxidation of hydroxyl radicals. Copyright © 2013 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  3. Screening effects on 12C+12C fusion reaction

    Science.gov (United States)

    Koyuncu, F.; Soylu, A.

    2018-05-01

    One of the important reactions for nucleosynthesis in the carbon burning phase in high-mass stars is the 12C+12C fusion reaction. In this study, we investigate the influences of the nuclear potentials and screening effect on astrophysically interesting 12C+12C fusion reaction observables at sub-barrier energies by using the microscopic α–α double folding cluster (DFC) potential and the proximity potential. In order to model the screening effects on the experimental data, a more general exponential cosine screened Coulomb (MGECSC) potential including Debye and quantum plasma cases has been considered in the calculations for the 12C+12C fusion reaction. In the calculations of the reaction observables, the semi-classical Wentzel-Kramers-Brillouin (WKB) approach and coupled channel (CC) formalism have been used. Moreover, in order to investigate how the potentials between 12C nuclei produce molecular cluster states of 24Mg, the normalized resonant energy states of 24Mg cluster bands have been calculated for the DFC potential. By analyzing the results produced from the fusion of 12C+12C, it is found that taking into account the screening effects in terms of MGECSC is important for explaining the 12C+12C fusion data, and the microscopic DFC potential is better than the proximity potential in explaining the experimental data, also considering that clustering is dominant for the structure of the 24Mg nucleus. Supported by the Turkish Science and Research Council (TÜBİTAK) with (117R015)

  4. Effects of carbon source and carbon content on electrochemical performances of Li{sub 4}Ti{sub 5}O{sub 12}/C prepared by one-step solid-state reaction

    Energy Technology Data Exchange (ETDEWEB)

    Hu Xuebu [College of Chemistry and Materials Science, Sichuan Normal University, Chengdu, Sichuan 610066 (China); Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu, Sichuan 610041 (China); Lin Ziji [China National Quality Supervision and Inspection Center for Alcoholic Beverage Products and Processed Food, Luzhou, Sichuan 646100 (China); Yang Kerun [Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu, Sichuan 610041 (China); Hua, Yongjian [China Aviation Lithium Battery Co. Ltd., Luoyang, Henan 471009 (China); Deng Zhenghua, E-mail: zhdeng@cioc.ac.cn [Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu, Sichuan 610041 (China)

    2011-05-30

    Highlights: > A simple route to prepare the Li{sub 4}Ti{sub 5}O{sub 12}/C by one-step solid-state reaction. > Carbon source and carbon content are two important factors on the electrochemical performances of Li{sub 4}Ti{sub 5}O{sub 12}/C. > As-prepared Li{sub 4}Ti{sub 5}O{sub 12}/C under optimized conditions shows excellent electrochemical performances. - Abstract: Li{sub 4}Ti{sub 5}O{sub 12}/C composites were synthesized by one-step solid-state reaction method using four commonly used organic compounds or organic polymers as carbon source, i.e., polyacrylate acid (PAA), citric acid (CA), maleic acid (MA) and polyvinyl alcohol (PVA). The physical characteristics of Li{sub 4}Ti{sub 5}O{sub 12}/C composites were investigated by X-ray diffraction, electron microscopy, Raman spectroscopy, particle size distribution and thermogravimetry-derivative thermogravimetry techniques. Their electrochemical properties were characterized by cyclic voltammograms, electrochemical impedance spectra, constant current charge-discharge and rate charge-discharge. These analyses indicated that the carbon source and carbon content have a great effect on the physical and electrochemical performances of Li{sub 4}Ti{sub 5}O{sub 12}/C composites. An ideal carbon source and appropriate carbon content effectively improved the electrical contact between the Li{sub 4}Ti{sub 5}O{sub 12} particles, which enhanced the discharge capacity and rate capability of Li{sub 4}Ti{sub 5}O{sub 12}/C composites. PAA was the best carbon source for the synthesis of Li{sub 4}Ti{sub 5}O{sub 12}/C composites. When the carbon content was 3.49 wt.% (LiOH.H{sub 2}O/PAA molar ratio of 1), as-prepared Li{sub 4}Ti{sub 5}O{sub 12}/C showed the maximum discharge capacity. At 0.2 C, initial capacity of the optimized sample was 168.6 mAh g{sup -1} with capacity loss of 2.8% after 50 cycles. At 8 and 10 C, it showed discharge capacities of 143.5 and 132.7 mAh g{sup -1}, with capacity loss of 8.7 and 9.9% after 50 cycles

  5. Calibration of an analyzing magnet using the 12C(d, p0)13C nuclear reaction with a thick carbon target

    Science.gov (United States)

    Andrade, E.; Canto, C. E.; Rocha, M. F.

    2017-09-01

    The absolute energy of an ion beam produced by an accelerator is usually determined by an electrostatic or magnetic analyzer, which in turn must be calibrated. Various methods for accelerator energy calibration are extensively reported in the literature, like nuclear reaction resonances, neutron threshold, and time of flight, among others. This work reports on a simple method to calibrate the magnet associated to a vertical 5.5 MV Van de Graaff accelerator. The method is based on bombarding with deuteron beams a thick carbon target and measuring with a surface barrier detector the particle energy spectra produced. The analyzer magnetic field is measured for each spectrum and the beam energy is deduced by the best fit of the simulation of the spectrum with the SIMNRA code that includes 12C(d,p0)13C nuclear cross sections.

  6. How does the carbon fusion reaction happen in stars?

    Directory of Open Access Journals (Sweden)

    X. Tang

    2013-09-01

    Full Text Available The 12C + 12C fusion reaction is one of the most important reactions in the stellar evolution. Due to its compli-cated reaction mechanism, there is great uncertainty in the reaction rate which limits our understanding of vari-ous stellar objects, such as explosions on the surface of neutron stars, white dwarf (type Ia supernovae, and massive stellar evolution. In this paper, I will review the challenges in the study of carbon burning. I will also report recent re-sults from our studies: 1 an upper limit for the 12C + 12C fusion cross sections, 2 measurement of the 12C + 12C at deep sub-barrier energies, 3 a new measurement of the 12C(12C, n reaction. The outlook for the studies of the astrophysical heavy-ion fusion reactions will also be presented.

  7. How does the carbon fusion reaction happen in stars?

    International Nuclear Information System (INIS)

    Tang, X.; Bucher, B.; Fang, X.; Notani, M.; Tan, W.P.; Mooney, P.; Li, Y.; Esbensen, H.; Jiang, C.L.; Rehm, K.E.; Lin, C.J; Brown, E.

    2012-01-01

    The 12 C + 12 C fusion reaction is one of the most important reactions in the stellar evolution. Due to its complicated reaction mechanism, there is great uncertainty in the reaction rate which limits our understanding of various stellar objects, such as massive stellar evolution, explosions on neutron stars, and supernovae from accreting white dwarf stars. In this paper, I will review the challenges in the study of carbon burning. I will also report recent results from our studies: 1) an upper limit for the 12 C + 12 C fusion cross sections, 2) measurement of the 12 C + 12 C at deep sub-barrier energies, and 3) a new measurement of the 12 C( 12 C, n) reaction. The outlook for the studies of the astrophysical heavy-ion fusion reactions will also be presented

  8. Cascade enzymatic reactions for efficient carbon sequestration.

    Science.gov (United States)

    Xia, Shunxiang; Zhao, Xueyan; Frigo-Vaz, Benjamin; Zheng, Wenyun; Kim, Jungbae; Wang, Ping

    2015-04-01

    Thermochemical processes developed for carbon capture and storage (CCS) offer high carbon capture capacities, but are generally hampered by low energy efficiency. Reversible cascade enzyme reactions are examined in this work for energy-efficient carbon sequestration. By integrating the reactions of two key enzymes of RTCA cycle, isocitrate dehydrogenase and aconitase, we demonstrate that intensified carbon capture can be realized through such cascade enzymatic reactions. Experiments show that enhanced thermodynamic driving force for carbon conversion can be attained via pH control under ambient conditions, and that the cascade reactions have the potential to capture 0.5 mol carbon at pH 6 for each mole of substrate applied. Overall it manifests that the carbon capture capacity of biocatalytic reactions, in addition to be energy efficient, can also be ultimately intensified to approach those realized with chemical absorbents such as MEA. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. I. Activation energies for the gas phase reactions of hydrogen atom with carbon monoxide and with ethylene. II. Rate constants for the reactions of benzyl cation with triethylphosphine and with triethylarsine in 1,2-dichloroethane

    International Nuclear Information System (INIS)

    Wang, H.Y.

    1976-01-01

    Two H-atom reactions H + CO + H 2 → HCO + H 2 and H + C 2 H 4 → C 2 H 5 * were separately studied from room temperature to about 100 0 C, and the activation energies for these two reactions were determined in this temperature range. For H + C 2 H 4 system, a small activation energy of 0.2 kcal/mole was obtained in the present narrow temperature range. The low activation energy indicates that the pre-exponential factor has a predominant contribution to the rate constant of this reaction and has about the same magnitude as that of the rate constant. For H + CO system, a fairly large activation energy of more than 7 kcal/mole was speculated in the potential energy surfaces of the system. The activation energy obtained in the present work, however, has a low value of about 2 kcal/mole. This low value reveals the low level of crossing of this reaction in the potential energy surface and thus indicates considerable complexity involved in the surface. Carbonium ions can be formed from chosen solutes in pulse-irradiated 1,2-dichloroethane (RCl) solutions. Upon irradiation, the electrons generated from the ionization of the solvent become localized on chloride ions as a result of their reaction with the neutral solvent molecules. The solvent counterion, RCl + , on the other hand, is free to exchange charge with the solute molecule. By choosing appropriate solutes, carbonium ion can be formed through a dissociative ionization process in the exchange. The benzyl cation was formed from its precursor compound dibenzylmercury and its reactions with two nucleophiles, triethylphosphine and triethylarsine, were separately studied. The formation and decay of benzyl cation were observed at 363 nm, the position of the maximum of its absorption band, and the second-order rate constants for the two reactions were determined at room temperature

  10. Reaction of yttrium polonides with carbon dioxide

    International Nuclear Information System (INIS)

    Abakumov, A.S.; Khokhlov, A.D.; Reznikova, N.F.

    1986-01-01

    It has been proved that heating of yttrium and tantalum in carbon dioxide to 500 and 800 0 C alters the gas phase composition, causing formation of carbon monoxide and reduction of oxygen content. A study of the thermal stability of yttrium polonides in carbon dioxide showed that yttrium sesqui- and monopolonides decompose at 400-430 0 C. The temperature dependence of the vapor pressure of polonium obtained upon decomposition of the referred polonides has been determined in a carbon dioxide environment radiotensometrically. The enthalpy of the process calculated from this dependence is close to the enthalpy of vaporization of elemental polonium in vacuo. The mechanism of the reactions has been suggested

  11. Reactions on carbon anodes in aluminium electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Eidet, Trygve

    1997-12-31

    The consumption of carbon anodes and energy in aluminium electrolysis is higher than what is required theoretically. This thesis studies the most important of the reactions that consume anode materials. These reactions are the electrochemical anode reaction and the airburn and carboxy reactions. The first part of the thesis deals with the kinetics and mechanism of the electrochemical anode reaction using electrochemical impedance spectroscopy. The second part deals with air and carboxy reactivity of carbon anodes and studies the effects of inorganic impurities on the reactivity of carbon anodes in the aluminium industry. Special attention is given to sulphur since its effect on the carbon gasification is not well understood. Sulphur is always present in anodes, and it is expected that the sulphur content of available anode cokes will increase in the future. It has also been suggested that sulphur poisons catalyzing impurities in the anodes. Other impurities that were investigated are iron, nickel and vanadium, which are common impurities in anodes which have been reported to catalyze carbon gasification. 88 refs., 92 figs., 24 tabs.

  12. Chemical reactions confined within carbon nanotubes.

    Science.gov (United States)

    Miners, Scott A; Rance, Graham A; Khlobystov, Andrei N

    2016-08-22

    In this critical review, we survey the wide range of chemical reactions that have been confined within carbon nanotubes, particularly emphasising how the pairwise interactions between the catalysts, reactants, transition states and products of a particular molecular transformation with the host nanotube can be used to control the yields and distributions of products of chemical reactions. We demonstrate that nanoscale confinement within carbon nanotubes enables the control of catalyst activity, morphology and stability, influences the local concentration of reactants and products thus affecting equilibria, rates and selectivity, pre-arranges the reactants for desired reactions and alters the relative stability of isomeric products. We critically evaluate the relative advantages and disadvantages of the confinement of chemical reactions inside carbon nanotubes from a chemical perspective and describe how further developments in the controlled synthesis of carbon nanotubes and the incorporation of multifunctionality are essential for the development of this ever-expanding field, ultimately leading to the effective control of the pathways of chemical reactions through the rational design of multi-functional carbon nanoreactors.

  13. Pycnonuclear 12C+12C reaction at zero temperature

    International Nuclear Information System (INIS)

    Gasques, L R; Beard, M; Chamon, L C; Wiescher, M

    2005-01-01

    We present pycnonuclear reaction calculations for a one-component ionic crystal at zero temperature considering different theoretical approaches. The rates depend directly on the determination of the astrophysical S-factor at low energies, which has been obtained through the barrier penetration formalism. A totally parameter-free model for the real part of the nuclear interaction has been employed in the calculation of 12 C+ 12 C fusion cross sections

  14. Reactions of sulphur mustard on impregnated carbons.

    Science.gov (United States)

    Prasad, G K; Singh, Beer

    2004-12-31

    Activated carbon of surface area 1100 m2/gm is impregnated with 4% sodium hydroxide plus 3% Cr(VI) as CrO3 with and without 5% ethylene diamine (EDA), 4% magnesium nitrate and 5% ruthenium chloride by using their aqueous solutions. These carbons are characterized for surface area analysis by BET conventional method and exposed to the vapours of sulphur mustard (HD) at room temperature (30 degrees C). After 24 h, the reaction products are extracted in dichloromethane and analyzed using gas chromatography and mass spectrometry (GC-MS). Hemisulphur mustard, thiodiglycol, 1,4-oxathiane are observed to be the products of reaction between sulphur mustard and NaOH/CrO3/C system, whereas on NaOH/CrO3/EDA/C system HD reacted to give 1,4-thiazane. On Mg(NO3)2/C system it gave hemisulphur mustard and thiodiglycol. On RuCl3/C system it degraded to divinyl sulphone. Residual sulphur mustard is observed along with reaction products in all systems studied. Reaction mechanisms are also proposed for these interesting surface reactions. Above-mentioned carbons can be used in filtration systems for protection against hazardous gases such as sulphur mustard.

  15. Reactions of sulphur mustard on impregnated carbons

    International Nuclear Information System (INIS)

    Prasad, G.K.; Singh, Beer

    2004-01-01

    Activated carbon of surface area 1100 m 2 /gm is impregnated with 4% sodium hydroxide plus 3% Cr(Vi) as CrO 3 with and without 5% ethylene diamine (EDA), 4% magnesium nitrate and 5% ruthenium chloride by using their aqueous solutions. These carbons are characterized for surface area analysis by BET conventional method and exposed to the vapours of sulphur mustard (HD) at room temperature (30 deg. C). After 24 h, the reaction products are extracted in dichloromethane and analyzed using gas chromatography and mass spectrometry (GC-MS). Hemisulphur mustard, thiodiglycol, 1,4-oxathiane are observed to be the products of reaction between sulphur mustard and NaOH/CrO 3 /C system, whereas on NaOH/CrO 3 /EDA/C system HD reacted to give 1,4-thiazane. On Mg(NO 3 ) 2 /C system it gave hemisulphur mustard and thiodiglycol. On RuCl 3 /C system it degraded to divinyl sulphone. Residual sulphur mustard is observed along with reaction products in all systems studied. Reaction mechanisms are also proposed for these interesting surface reactions. Above-mentioned carbons can be used in filtration systems for protection against hazardous gases such as sulphur mustard

  16. Substitution reactions of carbon nanotube template

    Science.gov (United States)

    Li, Chi Pui; Chen, Ying; Gerald, John Fitz

    2006-05-01

    Substitution reactions between carbon nanotube (CNT) template and SiO with the formation of carbon rich silicon oxide nanowires (SiO-C-NWs) have been investigated using transmission electron microscopy and x-ray energy dispersive spectroscopy. The reaction was carried out by thermal annealing at 1200°C for 1h of a mixture of silicon monoxide (SiO) and iron (II) phthalocyanine, FeC32N8H16 (FePc) powders. Multiwalled CNTs were produced first via pyrolysis of FePc at a lower temperature (1000°C ). SiO vapors reacted with the CNTs at higher temperatures to produce amorphous SiO-C-NWs with a uniform diameter and a length in tens of micrometers. The special bamboolike structure of the CNTs allows the reaction to start from the external surface of the tubes and transform each CNT into a solid nanowire section by section.

  17. Oxygen evolution reaction in nanoconfined carbon nanotubes

    Science.gov (United States)

    Li, Ying; Lu, Xuefeng; Li, Yunfang; Zhang, Xueqing

    2018-05-01

    Improving oxygen electrochemistry through nanoscopic confinement has recently been highlighted as a promising strategy. In-depth understanding the role of confinement is therefore required. In this study, we simulate the oxygen evolution reaction (OER) on iron oxide nanoclusters under confinement of (7,7) and (8,8) armchair carbon nanotubes (CNTs). The free energies of the four proton coupled electron transfer (PCET) steps and the OER overpotentials are calculated. The Fe4O6 nanocluster confined in (7,7) CNT is found to be the most active for OER among the systems considered in this work. This leads to an increase in catalytic efficiency of OER compared to the hematite (110) surface, which was reported recently as an active surface towards OER. The calculated results show that the OER overpotential depends strongly on the magnetic properties of the iron oxide nanocluster. These findings are helpful for experimental design of efficient catalyst for water splitting applications.

  18. Modeling the reactions catalyzed by coenzyme B12-dependent enzymes.

    Science.gov (United States)

    Sandala, Gregory M; Smith, David M; Radom, Leo

    2010-05-18

    Enzymes accelerate chemical reactions with an exceptional selectivity that makes life itself possible. Understanding the factors responsible for this efficient catalysis is of utmost importance in our quest to harness the tremendous power of enzymes. Computational chemistry has emerged as an important adjunct to experimental chemistry and biochemistry in this regard, because it provides detailed insights into the relationship between structure and function in a systematic and straightforward manner. In this Account, we highlight our recent high-level theoretical investigations toward this end in studying the radical-based reactions catalyzed by enzymes dependent on coenzyme B(12) (or adenosylcobalamin, AdoCbl). In addition to their fundamental position in biology, the AdoCbl-dependent enzymes represent a valuable framework within which to understand Nature's method of efficiently handling high-energy species to execute very specific reactions. The AdoCbl-mediated reactions are characterized by the interchange of a hydrogen atom and a functional group on adjacent carbon atoms. Our calculations are consistent with the conclusion that the main role of AdoCbl is to provide a source of radicals, thus moving the 1,2-rearrangements onto the radical potential energy surface. Our studies also show that the radical rearrangement step is facilitated by partial proton transfer involving the substrate. Specifically, we observe that the energy requirements for radical rearrangement are reduced dramatically with appropriate partial protonation or partial deprotonation or sometimes (synergistically) both. Such interactions are particularly relevant to enzyme catalysis, because it is likely that the local amino acid environment in the active site of an enzyme can function in this capacity through hydrogen bonding. Finally, our calculations indicate that the intervention of a very stable radical along the reaction pathway may inactivate the enzyme, demonstrating that sustained

  19. Kinetic study of the reaction of uranium with various carbon-containing gases

    International Nuclear Information System (INIS)

    Feron, G.

    1963-09-01

    The kinetic study of the reaction U + CO 2 and U + CO has been performed by a thermogravimetric method on a spherical uranium powder, in temperature ranges respectively from 460 to 690 deg. C and from 570 to 850 deg. C. The reaction with carbon dioxide leads to uranium dioxide. A carbon deposition takes place at the same time. The global reactions is the result of two reactions: U + 2 CO 2 → UO 2 + 2 CO U + CO 2 → UO 2 + C The reaction with carbon monoxide leads to a mixture of dioxide UO 2 , dicarbide UC 2 and free carbon. The main reaction can be written. U + CO → 1/2 UO 2 + 1/2 UC 2 The free carbon results of the disproportionation of the carbon monoxide. A remarkable separation of the two phases UO 2 and UC 2 can be observed. A mechanism accounting for the phenomenon has been proposed. The two reactions U + CO 2 and U + CO begin with a long germination period, after which, the reaction velocity seems to be limited in both cases by the ionic diffusion of oxygen through the uranium dioxide. (author) [fr

  20. Kinetic study of the reaction of uranium with various carbon-containing gases; Etude cinetique de la reaction sur l'uranium de differents gaz carbones

    Energy Technology Data Exchange (ETDEWEB)

    Feron, G [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1963-09-15

    The kinetic study of the reaction U + CO{sub 2} and U + CO has been performed by a thermogravimetric method on a spherical uranium powder, in temperature ranges respectively from 460 to 690 deg. C and from 570 to 850 deg. C. The reaction with carbon dioxide leads to uranium dioxide. A carbon deposition takes place at the same time. The global reactions is the result of two reactions: U + 2 CO{sub 2} {yields} UO{sub 2} + 2 CO U + CO{sub 2} {yields} UO{sub 2} + C The reaction with carbon monoxide leads to a mixture of dioxide UO{sub 2}, dicarbide UC{sub 2} and free carbon. The main reaction can be written. U + CO {yields} 1/2 UO{sub 2} + 1/2 UC{sub 2} The free carbon results of the disproportionation of the carbon monoxide. A remarkable separation of the two phases UO{sub 2} and UC{sub 2} can be observed. A mechanism accounting for the phenomenon has been proposed. The two reactions U + CO{sub 2} and U + CO begin with a long germination period, after which, the reaction velocity seems to be limited in both cases by the ionic diffusion of oxygen through the uranium dioxide. (author) [French] L'etude cinetique des reactions U sol + CO{sub 2} gaz et U sol + CO gaz a ete effectuee par thermogravirnetrie sur une poudre d'uranium a grains spheriques, les domaines de temperature etudies s'etendant respectivement de 460 a 690 deg. C et de 570 a 850 deg. C. L'action du dioxyde de carbone conduit au dioxyde d'uranium UO{sub 2}; il se produit en meme temps un depot de carbone. La reaction globale resulte des deux reactions: U + 2 CO{sub 2} {yields} UO{sub 2} + 2 CO U + CO{sub 2} {yields} UO{sub 2} + C Le mono-oxyde de carbone conduit a un melange de dioxyde UO{sub 2}, de dicarbure UC{sub 2} et de carbone libre. La reaction principale s'ecrit: U + CO {yields} 1/2 UO{sub 2} + 1/2 UC{sub 2} Le carbone libre provient de la dismutation du mono-oxyde de carbone. On observe une separation remarquable des deux phases UO{sub 2} et UC{sub 2}; un mecanisme rendant compte de ce phenomene a

  1. Cluster correlation effects in 12C+12C and 14N+10B fusion-evaporation reactions

    Directory of Open Access Journals (Sweden)

    Morelli L.

    2015-01-01

    Full Text Available The decay of highly excited states of 24Mg is studied in fusion evaporation events completely detected in charge in the reactions 12C+12C and 14N+10B at 95 and 80 MeV incident energy respectively. The comparison of light charged particles measured spectra with statistical model predictions suggests that the dominant reaction mechanism is compound nucleus (CN formation and decay. However, in both reactions, a discrepancy with statistical expectations is found for α particles detected in coincidence with Carbon, Oxigen and Neon residues. The comparison between the two reactions shows that this discrepancy is only partly explained by an entrance channel effect. Evidence for cluster correlations in excited 24Mg CN is suggested by the comparison between the measured and calculated branching ratios for the channels involving α particles.

  2. Reaction of titanium polonides with carbon dioxide

    International Nuclear Information System (INIS)

    Abakumov, A.S.; Malyshev, M.L.; Reznikova, N.F.

    1987-01-01

    It has been ascertained that heating titanium and tantalum in carbon dioxide to temperatures of 500 or 800 0 C alters the composition of the gas phase, causing the advent of carbon monoxide and lowering the oxygen content. Investigation of the thermal stability of titanium polonides in a carbon dioxide medium has shown that titanium mono- and hemipolonides are decomposed at temperatures below 350 0 C. The temperature dependence of the vapor pressure of polonium produced in the decomposition of these polonides in a carbon dioxide medium have been determined by a radiotensimetric method. The enthalpy of the process, calculated from this relationship, is close to the enthalpy of vaporization of elementary polonium in vacuo

  3. Friction stir processing on high carbon steel U12

    Energy Technology Data Exchange (ETDEWEB)

    Tarasov, S. Yu., E-mail: tsy@ispms.ru; Rubtsov, V. E., E-mail: rvy@ispms.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Melnikov, A. G., E-mail: melnikov-ag@tpu.ru [National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation)

    2015-10-27

    Friction stir processing (FSP) of high carbon steel (U12) samples has been carried out using a milling machine and tools made of cemented tungsten carbide. The FSP tool has been made in the shape of 5×5×1.5 mm. The microstructural characterization of obtained stir zone and heat affected zone has been carried out. Microhardness at the level of 700 MPa has been obtained in the stir zone with microstructure consisting of large grains and cementitte network. This high-level of microhardness is explained by bainitic reaction developing from decarburization of austenitic grains during cementite network formation.

  4. On reaction of titanium polonides with carbon dioxide

    International Nuclear Information System (INIS)

    Abakumov, A.S.; Malyshev, M.L.; Reznikova, N.F.

    1986-01-01

    The reaction between titanium polonides and carbon dioxide has been studied by comparing titanium polonide thermal resistance in vacuum and in carbon dioxide. The investigation has shown that titanium mono- and semipolonides fail at temperatures below 350 deg C. Temperature dependence of polonium vapor pressure prepared at failure of the given polonides is determined by the radiotensiometry in carbon dioxide. Enthalpy calculated for this dependence is close to the enthalpy of elementary polonium evaporation in vacuum

  5. A high-performance mesoporous carbon supported nitrogen-doped carbon electrocatalyst for oxygen reduction reaction

    Science.gov (United States)

    Xu, Jingjing; Lu, Shiyao; Chen, Xu; Wang, Jianan; Zhang, Bo; Zhang, Xinyu; Xiao, Chunhui; Ding, Shujiang

    2017-12-01

    Investigating low-cost and highly active electrocatalysts for oxygen reduction reactions (ORR) is of crucial importance for energy conversion and storage devices. Herein, we design and prepare mesoporous carbon supported nitrogen-doped carbon by pyrolysis of polyaniline coated on CMK-3. This electrocatalyst exhibits excellent performance towards ORR in alkaline media. The optimized nitrogen-doped mesoporous electrocatalyst show an onset potential (E onset) of 0.95 V (versus reversible hydrogen electrode (RHE)) and half-wave potential (E 1/2) of 0.83 V (versus RHE) in 0.1 M KOH. Furthermore, the as-prepared catalyst presents superior durability and methanol tolerance compared to commercial Pt/C indicating its potential applications in fuel cells and metal-air batteries.

  6. Reaction studies of hot silicon, germanium and carbon atoms

    International Nuclear Information System (INIS)

    Gaspar, P.P.

    1990-01-01

    The goal of this project was to increase the authors understanding of the interplay between the kinetic and electronic energy of free atoms and their chemical reactivity by answering the following questions: (1) what is the chemistry of high-energy carbon silicon and germanium atoms recoiling from nuclear transformations; (2) how do the reactions of recoiling carbon, silicon and germanium atoms take place - what are the operative reaction mechanisms; (3) how does the reactivity of free carbon, silicon and germanium atoms vary with energy and electronic state, and what are the differences in the chemistry of these three isoelectronic atoms? This research program consisted of a coordinated set of experiments capable of achieving these goals by defining the structures, the kinetic and internal energy, and the charge states of the intermediates formed in the gas-phase reactions of recoiling silicon and germanium atoms with silane, germane, and unsaturated organic molecules, and of recoiling carbon atoms with aromatic molecules. The reactions of high energy silicon, germanium, and carbon atoms created by nuclear recoil were studied with substrates chosen so that their products illuminated the mechanism of the recoil reactions. Information about the energy and electronic state of the recoiling atoms at reaction was obtained from the variation in end product yields and the extent of decomposition and rearrangement of primary products (usually reactive intermediates) as a function of total pressure and the concentration of inert moderator molecules that remove kinetic energy from the recoiling atoms and can induce transitions between electronic spin states. 29 refs

  7. Optical Excitation of Carbon Nanotubes Drives Localized Diazonium Reactions

    Science.gov (United States)

    2016-01-01

    Covalent chemistries have been widely used to modify carbon nanomaterials; however, they typically lack the precision and efficiency required to directly engineer their optical and electronic properties. Here, we show, for the first time, that visible light which is tuned into resonance with carbon nanotubes can be used to drive their functionalization by aryldiazonium salts. The optical excitation accelerates the reaction rate 154-fold (±13) and makes it possible to significantly improve the efficiency of covalent bonding to the sp2 carbon lattice. Control experiments suggest that the reaction is dominated by a localized photothermal effect. This light-driven reaction paves the way for precise nanochemistry that can directly tailor carbon nanomaterials at the optical and electronic levels. PMID:27588432

  8. Vibrationally Excited Carbon Monoxide Produced via a Chemical Reaction Between Carbon Vapor and Oxygen

    Science.gov (United States)

    Jans, Elijah R.; Eckert, Zakari; Frederickson, Kraig; Rich, Bill; Adamovich, Igor V.

    2017-06-01

    Measurements of the vibrational distribution function of carbon monoxide produced via a reaction between carbon vapor and molecular oxygen has shown a total population inversion on vibrational levels 4-7. Carbon vapor, produced using an arc discharge to sublimate graphite, is mixed with an argon oxygen flow. The excited carbon monoxide is vibrationally populated up to level v=14, at low temperatures, T=400-450 K, in a collision-dominated environment, 15-20 Torr, with total population inversions between v=4-7. The average vibrational energy per CO molecule formed by the reaction is 0.6-1.2 eV/molecule, which corresponds to 10-20% of the reaction enthalpy. Kinetic modeling of the flow reactor, including state specific vibrational processes, was performed to infer the vibrational distribution of the products of the reaction. The results show viability of developing of a new chemical CO laser from the reaction of carbon vapor and oxygen.

  9. Selective free radical reactions using supercritical carbon dioxide.

    Science.gov (United States)

    Cormier, Philip J; Clarke, Ryan M; McFadden, Ryan M L; Ghandi, Khashayar

    2014-02-12

    We report herein a means to modify the reactivity of alkenes, and particularly to modify their selectivity toward reactions with nonpolar reactants (e.g., nonpolar free radicals) in supercritical carbon dioxide near the critical point. Rate constants for free radical addition of the light hydrogen isotope muonium to ethylene, vinylidene fluoride, and vinylidene chloride in supercritical carbon dioxide are compared over a range of pressures and temperatures. Near carbon dioxide's critical point, the addition to ethylene exhibits critical speeding up, while the halogenated analogues display critical slowing. This suggests that supercritical carbon dioxide as a solvent may be used to tune alkene chemistry in near-critical conditions.

  10. Reaction mechanisms for enhancing carbon dioxide mineral sequestration

    Science.gov (United States)

    Jarvis, Karalee Ann

    Increasing global temperature resulting from the increased release of carbon dioxide into the atmosphere is one of the greatest problems facing society. Nevertheless, coal plants remain the largest source of electrical energy and carbon dioxide gas. For this reason, researchers are searching for methods to reduce carbon dioxide emissions into the atmosphere from the combustion of coal. Mineral sequestration of carbon dioxide reacted in electrolyte solutions at 185°C and 2200 psi with olivine (magnesium silicate) has been shown to produce environmentally benign carbonates. However, to make this method feasible for industrial applications, the reaction rate needs to be increased. Two methods were employed to increase the rate of mineral sequestration: reactant composition and concentration were altered independently in various runs. The products were analyzed with complete combustion for total carbon content. Crystalline phases in the product were analyzed with Debye-Scherrer X-ray powder diffraction. To understand the reaction mechanism, single crystals of San Carlos Olivine were reacted in two solutions: (0.64 M NaHCO3/1 M NaCl) and (5.5 M KHCO3) and analyzed with scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), and fluctuation electron microscopy (FEM) to study the surface morphology, atomic crystalline structure, composition and amorphous structure. From solution chemistry studies, it was found that increasing the activity of the bicarbonate ion increased the conversion rate of carbon dioxide to magnesite. The fastest conversion, 60% conversion in one hour, occurred in a solution of 5.5 M KHCO3. The reaction product particles, magnesium carbonate, significantly increased in both number density and size on the coupon when the bicarbonate ion activity was increased. During some experiments reaction vessel corrosion also altered the mineral sequestration mechanism. Nickel ions from vessel

  11. Heterogeneously Catalysed Chemical Reactions in Carbon Dioxide Medium

    DEFF Research Database (Denmark)

    Musko, Nikolai E.

    In this PhD-study the different areas of chemical engineering, heterogeneous catalysis, supercritical fluids, and phase equilibrium thermodynamics have been brought together for selected reactions. To exploit the beneficial properties of supercritical fluids in heterogeneous catalysis, experimental...... studies of catalytic chemical reactions in dense and supercritical carbon dioxide have been complemented by the theoretical calculations of phase equilibria using advanced thermodynamic models. In the recent years, the use of compressed carbon dioxide as innovative, non-toxic and non-flammable, cheap......, and widely available reaction medium for many practical and industrial applications has drastically increased. Particularly attractive are heterogeneously catalysed chemical reactions. The beneficial use of CO2 is attributed to its unique properties at dense and supercritical states (at temperatures...

  12. Diagnostic Appraisal of Grade 12 Students' Understanding of Reaction Kinetics

    Science.gov (United States)

    Yan, Yaw Kai; Subramaniam, R.

    2016-01-01

    The study explored grade 12 students' understanding of reaction kinetics, a topic which has not been extensively explored in the chemistry education literature at this level. A 3-tier diagnostic instrument with 11 questions was developed--this format is of very recent origin and has been the subject of only a handful of studies. The findings…

  13. Deformation effects in the 20Ne+12C reaction

    International Nuclear Information System (INIS)

    Dey, A.; Bhattacharya, C.; Banerjee, K.; Kundu, S.; Mukhopadhyay, S.; Gupta, D.; Saha, R.; Bhattacharya, S.

    2004-01-01

    The present work has been performed with the aim to investigate the possible occurrence of highly deformed configurations of the 32 S di-nuclear systems which may be formed in the 20 Ne+ 12 C reaction by studying the properties of emitted light charged particles

  14. The Ligand Substitution Reactions of Hydrophobic Vitamin B12 ...

    African Journals Online (AJOL)

    South African Journal of Chemistry ... The equilibrium constants, K, for the reaction of five-membered heterocyclic nitrogenous bases (the azoles imidazole, pyrazole and 1,2,4-triazole) with displacement of ... Keywords: Hydrophobic vitamin B12, cobalt corrinoids, equilibrium constants, solvent polarity, trans influence.

  15. Reactions of carbon atoms in pulsed molecular beams

    Energy Technology Data Exchange (ETDEWEB)

    Reisler, H. [Univ. of Southern California, Los Angeles (United States)

    1993-12-01

    This research program consists of a broad scope of experiments designed to unravel the chemistry of atomic carbon in its two spin states, P and D, by using well-controlled initial conditions and state-resolved detection of products. Prerequisite to the proposed studies (and the reason why so little is known about carbon atom reactions), is the development of clean sources of carbon atoms. Therefore, in parallel with the studies of its chemistry and reaction dynamics, the authors continuously explore new, state-specific and efficient ways of producing atomic carbon. In the current program, C({sup 3}P) is produced via laser ablation of graphite, and three areas of study are being pursued: (i) exothermic reactions with small inorganic molecules (e.g., O{sub 2}, N{sub 2}O, NO{sub 2}) that can proceed via multiple pathways; (ii) the influence of vibrational and translational energy on endothermic reactions involving H-containing reactants that yield CH products (e.g., H{sub 2}O H{sub 2}CO); (iii) reactions of C({sup 3}P) with free radicals (e.g., HCO, CH{sub 3}O). In addition, the authors plan to develop a source of C({sup 1}D) atoms by exploiting the pyrolysis of diazotetrazole and its salts in the ablation source. Another important goal involves collaboration with theoreticians in order to obtain relevant potential energy surfaces, rationalize the experimental results and predict the roles of translational and vibrational energies.

  16. Excited states in 22Mg via the 12C(12C,2n)22Mg reaction

    International Nuclear Information System (INIS)

    Jewett, Cybele; Baktash, Cyrus; Bardayan, Daniel W.; Blackmon, Jeff C.; Chipps, K.; Galindo-Uribarri, Alfredo; Greife, U.; Gross, Carl J.; Jones, K. L.; Liang, Junjien; Livesay, Jake; Kozub, R. L.; Nesaraja, Caroline D; Radford, David C.; Sarazin, F.; Smith, Michael Scott; Thomas, J. S.; Yu, Chang-Hong

    2007-01-01

    The 12C(12C, 2n)22Mg reaction was measured with the CLARION array and the RMS separator at the Holifield Facility of Oak Ridge National Laboratory. This experiment was performed to gather more information on the excited states in 22Mg, which might be of relevance to recent radioactive ion beam measurements of the astrophysically important 21Na(p,γ)22Mg reaction. The results are compared to direct measurements, transfer experiments and a competing experiment performed with Gammasphere

  17. Neutrino and antineutrino charge-exchange reactions on 12C

    International Nuclear Information System (INIS)

    Samana, A. R.; Krmpotic, F.; Paar, N.; Bertulani, C. A.

    2011-01-01

    We extend the formalism of weak interaction processes, obtaining new expressions for the transition rates, which greatly facilitate numerical calculations, for both neutrino-nucleus reactions and muon capture. Explicit violation of the conserved vector current hypothesis by the Coulomb field, as well as development of a sum-rule approach for inclusive cross sections, has been worked out. We have done a thorough study of exclusive (ground-state) properties of 12 B and 12 N within the projected quasiparticle random phase approximation (PQRPA). Good agreement with experimental data achieved in this way put into evidence the limitations of the standard RPA and QRPA models, which come from the inability of the RPA to open the p 3/2 shell and from the nonconservation of the number of particles in the QRPA. The inclusive neutrino/antineutrino (ν/ν-tilde) reactions 12 C(ν,e - ) 12 N and 12 C(ν-tilde,e + ) 12 B are calculated within both the PQRPA and the relativistic QRPA. It is found that (i) the magnitudes of the resulting cross sections are close to the sum-rule limit at low energy, but significantly smaller than this limit at high energies, for both ν and ν-tilde; (ii) they increase steadily when the size of the configuration space is augmented, particularly for ν/ν-tilde energies >200 MeV; and (iii) they converge for sufficiently large configuration space and final-state spin. The quasi-elastic 12 C(ν,μ - ) 12 N cross section recently measured in the MiniBooNE experiment is briefly discussed. We study the decomposition of the inclusive cross section based on the degree of forbiddenness of different multipoles. A few words are dedicated to the ν/ν-tilde- 12 C charge-exchange reactions related to astrophysical applications.

  18. Reactions of carbonate radical with cobalt(II) aminopolycarboxylates

    International Nuclear Information System (INIS)

    Mandal, P.C.; Bardhan, D.K.; Bhattacharyya, S.N.

    1992-01-01

    Reactions of carbonate (CO 3 - radical) and bicarbonate (HCO 3 radical) radicals generated by photolysis of a carbonate or bicarbonate solution at pH 11.2 and 8.5, respectively, with Co(II) complexes of iminodiacetic acid (IDA) and ethylenediaminetetraacetic acid (EDTA) have been studied. The rate constants for the reactions were in the order of 10 6 -10 7 dm 3 mol -1 s -1 . From the time-resolved spectroscopy of the products formed after reaction of CO 3 - radical or HCO 3 radical, it is observed that CO 3 - radical or HCO 3 radical oxidize the metal center to its higher oxidation state. (author) 26 refs.; 2 figs.; 1 tab

  19. Heterogeneously Catalysed Aldol Reactions in Supercritical Carbon Dioxide as Innovative and Non-Flammable Reaction Medium

    DEFF Research Database (Denmark)

    Musko, Nikolai; Grunwaldt, Jan-Dierk

    2011-01-01

    Aldol reactions of several aldehydes have been investigated over acidic and basic catalysts in supercritical carbon dioxide at 180 bar and 100 °C. Both acidic (Amberlyst-15, tungstosilicic acid (TSA) on SiO2 and MCM-41) and basic (hydrotalcite) materials showed interesting performance in this pre...

  20. Olefination reactions of phosphorus-stabilized carbon nucleophiles.

    Science.gov (United States)

    Gu, Yonghong; Tian, Shi-Kai

    2012-01-01

    A range of phosphorus-stabilized carbon nucleophiles have been employed for alkene synthesis with high chemo-, regio-, and stereoselectivity. The Wittig, Horner-Wadsworth-Emmons, Horner-Wittig, and Evans-Akiba reactions utilize phosphonium-, phosphonate-, phosphine oxide-, and pentacoordinated phosphorane-stabilized carbanions as nucleophiles, respectively, to undergo olefination with aldehydes or ketones, and each of these transformations has its own advantages and limitations. Modifying the structures of these nucleophiles along with optimizing reaction conditions results in the formation of a wide variety of polysubstituted alkenes in a highly stereoselective manner. The olefination of imines with phosphonium ylides has recently emerged as a useful approach to tune the stereoselectivity for alkene synthesis. This review focuses on recent advances in the stereoselective olefination of phosphorus-stabilized carbon nucleophiles.

  1. Simulation of dual carbon-bromine stable isotope fractionation during 1,2-dibromoethane degradation.

    Science.gov (United States)

    Jin, Biao; Nijenhuis, Ivonne; Rolle, Massimo

    2018-06-01

    We performed a model-based investigation to simultaneously predict the evolution of concentration, as well as stable carbon and bromine isotope fractionation during 1,2-dibromoethane (EDB, ethylene dibromide) transformation in a closed system. The modelling approach considers bond-cleavage mechanisms during different reactions and allows evaluating dual carbon-bromine isotopic signals for chemical and biotic reactions, including aerobic and anaerobic biological transformation, dibromoelimination by Zn(0) and alkaline hydrolysis. The proposed model allowed us to accurately simulate the evolution of concentrations and isotope data observed in a previous laboratory study and to successfully identify different reaction pathways. Furthermore, we illustrated the model capabilities in degradation scenarios involving complex reaction systems. Specifically, we examined (i) the case of sequential multistep transformation of EDB and the isotopic evolution of the parent compound, the intermediate and the reaction product and (ii) the case of parallel competing abiotic pathways of EDB transformation in alkaline solution.

  2. Chemical Reactions in the Processing of Mosi2 + Carbon Compacts

    Science.gov (United States)

    Jacobson, Nathan S.; Lee, Kang N.; Maloy, Stuart A.; Heuer, Arthur H.

    1993-01-01

    Hot-pressing of MoSi2 powders with carbon at high temperatures reduces the siliceous grain boundary phase in the resultant compact. The chemical reactions in this process were examined using the Knudsen cell technique. A 2.3 wt pct oxygen MoSi2 powder and a 0.59 wt pct oxygen MoSi2 powder, both with additions of 2 wt pct carbon, were examined. The reduction of the siliceous grain boundary phase was examined at 1350 K and the resultant P(SiO)/P(CO) ratios interpreted in terms of the SiO(g) and CO(g) isobars on the Si-C-O predominance diagram. The MoSi2 + carbon mixtures were then heated at the hot-pressing temperature of 2100 K. Large weight losses were observed and could be correlated with the formation of a low-melting eutectic and the formation and vaporization of SiC.

  3. BOREAS TGB-12 Isotropic Carbon Dioxide Data over the NSA

    Science.gov (United States)

    Trumbore, Susan; Hall, Forrest G. (Editor); Sundquist, Eric; Winston, Greg; Conrad, Sara K. (Editor)

    2000-01-01

    The BOREAS TGB-12 team made measurements of soil carbon inventories, carbon concentration in soil gases, and rates of soil respiration at several sites to estimate the rates of carbon accumulation and turnover in each of the major vegetation types. This data set contains information on the carbon isotopic content of carbon dioxide sampled from soils in the NSA-OBS, NSA-YJP, and NSA-OJP sites. Data were collected from 14-Nov-1993 to 10-Oct-1996. The data are stored in tabular ASCII files.

  4. Method for producing bio-fuel that integrates heat from carbon-carbon bond-forming reactions to drive biomass gasification reactions

    Science.gov (United States)

    Cortright, Randy D [Madison, WI; Dumesic, James A [Verona, WI

    2011-01-18

    A low-temperature catalytic process for converting biomass (preferably glycerol recovered from the fabrication of bio-diesel) to synthesis gas (i.e., H.sub.2/CO gas mixture) in an endothermic gasification reaction is described. The synthesis gas is used in exothermic carbon-carbon bond-forming reactions, such as Fischer-Tropsch, methanol, or dimethylether syntheses. The heat from the exothermic carbon-carbon bond-forming reaction is integrated with the endothermic gasification reaction, thus providing an energy-efficient route for producing fuels and chemicals from renewable biomass resources.

  5. THE {sup 12}C + {sup 12}C REACTION AND THE IMPACT ON NUCLEOSYNTHESIS IN MASSIVE STARS

    Energy Technology Data Exchange (ETDEWEB)

    Pignatari, M. [Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Hirschi, R.; Bennett, M. [Astrophysics Group, EPSAM Institute, Keele University, Keele, ST5 5BG (United Kingdom); Wiescher, M.; Beard, M. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Gallino, R. [Universita' di Torino, Torino, Via Pietro Giuria 1, I-10126 Torino (Italy); Fryer, C.; Rockefeller, G. [Computational Physics and Methods (CCS-2), LANL, Los Alamos, NM 87545 (United States); Herwig, F.; Timmes, F. X., E-mail: marco.pignatari@unibas.ch [The Joint Institute for Nuclear Astrophysics, Notre Dame, IN 46556 (United States)

    2013-01-01

    Despite much effort in the past decades, the C-burning reaction rate is uncertain by several orders of magnitude, and the relative strength between the different channels {sup 12}C({sup 12}C, {alpha}){sup 20}Ne, {sup 12}C({sup 12}C, p){sup 23}Na, and {sup 12}C({sup 12}C, n){sup 23}Mg is poorly determined. Additionally, in C-burning conditions a high {sup 12}C+{sup 12}C rate may lead to lower central C-burning temperatures and to {sup 13}C({alpha}, n){sup 16}O emerging as a more dominant neutron source than {sup 22}Ne({alpha}, n){sup 25}Mg, increasing significantly the s-process production. This is due to the chain {sup 12}C(p, {gamma}){sup 13}N followed by {sup 13}N({beta} +){sup 13}C, where the photodisintegration reverse channel {sup 13}N({gamma}, p){sup 12}C is strongly decreasing with increasing temperature. Presented here is the impact of the {sup 12}C+{sup 12}C reaction uncertainties on the s-process and on explosive p-process nucleosynthesis in massive stars, including also fast rotating massive stars at low metallicity. Using various {sup 12}C+{sup 12}C rates, in particular an upper and lower rate limit of {approx}50,000 higher and {approx}20 lower than the standard rate at 5 Multiplication-Sign 10{sup 8} K, five 25 M {sub Sun} stellar models are calculated. The enhanced s-process signature due to {sup 13}C({alpha}, n){sup 16}O activation is considered, taking into account the impact of the uncertainty of all three C-burning reaction branches. Consequently, we show that the p-process abundances have an average production factor increased up to about a factor of eight compared with the standard case, efficiently producing the elusive Mo and Ru proton-rich isotopes. We also show that an s-process being driven by {sup 13}C({alpha}, n){sup 16}O is a secondary process, even though the abundance of {sup 13}C does not depend on the initial metal content. Finally, implications for the Sr-peak elements inventory in the solar system and at low metallicity are

  6. Absorption of carbon dioxide and isotope exchange rate of carbon in a reaction system between carbon dioxide and carbamic acid

    International Nuclear Information System (INIS)

    Takeshita, Kenji; Kitamoto, Asashi

    1985-01-01

    The performance of isotope separation of carbon-13 by chemical exchange between carbon dioxide and carbamic acid was studied. The working fluid used in the study was a solution of DNBA, (C 4 H 9 ) 2 NH and n-octane mixture. Factors related to the isotope exchange rate were measured, such as the absorption rate of carbon dioxide into the solution of DNBA and n-octane, the isotope exchange rate and the separation factor in the reaction between CO 2 and carbamic acid. The absorption of CO 2 into the working fluid was the sum of chemical absorption by DNBA and physical absorption by n-octane. The absorption of carbon dioxide into the working fluid was negligible at temperatures over 90 0 C, but increased gradually at lower temperatures. Carbon dioxide was absorbed into DNBA by chemical absorption, and DNBA was converted to carbamic acid by the reaction. The reaction for synthesis and decomposition of carbamic acid was reversible. The separation factor in equilibrium reached a large value at lower temperatures. The isotope exchange rate between gas and liquid was proportional to the product of the concentration of carbamic acid and the concentration of CO 2 by physical absorption. The isotope separation of carbon by chemical exchange reaction is better operated under the conditions of lower temperature and higher pressure. (author)

  7. The differential cross section of the 12C(p,p)12C reaction near the resonance at energy 1.726 MeV

    International Nuclear Information System (INIS)

    Duvanov, S.M.; Kobzev, A.P.

    1996-01-01

    New experimental results on the differential cross section of the 12 C(p,p) 12 C reaction near the separate resonance at 1726 keV were obtained for the 170 deg scattering angle. The cross section measured with a thin target has been used for computer simulation of the spectra measured for a defined initial proton energy for two thick targets. The precision measurements of the proton energies have been carried out using the resonance of 27 Al(p,γ) 28 Si reaction at 1726.0 keV. The energy scale of the excitation function of the 12 C(p,p) 12 C reaction near the resonance at 1726 keV has been defined more exactly. It will improve the precision of depth profiling of carbon in solids. 11 refs., 5 figs., 1 tab

  8. Reaction between molybdenum and carbon, and several carbides

    International Nuclear Information System (INIS)

    Morozumi, Shotaro; Kikuchi, Michio; Sugai, Shinzo; Hayashi, Masaaki.

    1980-01-01

    Diffusion couples of molybdenum with carbon and several carbides, i.e. B 4 C, SiC, TiC, and TaC, respectively, were heated for up to 3.6 x 10 5 s at various temperatures ranging from 1373 to 2223 K. The couples were then examined for composition, growth rate, structure, and hardness of reaction layers. Main results obtained are as follows: (1) In the Mo-C system, only Mo 2 C layer was formed at below 1873 K, while two sub- layers consisted of Mo 2 C and eta (MoC sub(1-x)), respectively, were found at above 1873 K. The activation energy for growth of total layer was 374 kJ/mol. (2) In the Mo-B 4 C system, two sub-layers consisted of Mo 2 B and MoB, respectively, with dispersed carbon particles were formed. (3) In the Mo-SiC system, Mo 2 C layer, including eta (MoC sub(1-x)) phase at high temperature, mixture of Mo 2 C and Mo 3 Si 2 phases, and Mo 3 Si 2 phase in order from the Mo side were formed. The activation energy for growth of total layer was 477 kJ/mol. (4) In the Mo-TiC system, two kinds of TiC in point of view of free carbon content were used; one is with 0.2% free carbon and the other is with 0.01%. In the Mo-TiC with 0.2% free carbon system, two sub-layers, i.e. relatively thick Mo 2 C layer and thin (Ti, Mo)C layer, were formed, while in the Mo-TiC with 0.01% free carbon system two thin sub-layers, Mo 2 C and (Ti, Mo)C, were formed; the Mo 2 C layer in the latter case was very thin and was not found after short time heating at low temperature. The activation energy for growth of Mo 2 C layer in the former system was 393 kJ/mol. (5) In the Mo-TaC with 0.02% free carbon system, two thin sub-layers, (Mo, Ta) 2 C and (Ta, Mo)C, were observed. (6) TEM studies on the interface between Mo (bcc) and Mo 2 C (hcp) showed that there was the following orientation relation, called as the Burgers relation, between these two phases; (110)sub(Mo)//(0001)sub(Mo 2 C), sub(Mo)// - 0>sub(Mo 2 C). (author)

  9. Mineral carbonation of gaseous carbon dioxide using a clay-hosted cation exchange reaction.

    Science.gov (United States)

    Kang, Il-Mo; Roh, Ki-Min

    2013-01-01

    The mineral carbonation method is still a challenge in practical application owing to: (1) slow reaction kinetics, (2) high reaction temperature, and (3) continuous mineral consumption. These constraints stem from the mode of supplying alkaline earth metals through mineral acidification and dissolution. Here, we attempt to mineralize gaseous carbon dioxide into calcium carbonate, using a cation exchange reaction of vermiculite (a species of expandable clay minerals). The mineralization is operated by draining NaCI solution through vermiculite powders and continuously dropping into the pool of NaOH solution with CO2 gas injected. The mineralization temperature is regulated here at 293 and 333 K for 15 min. As a result of characterization, using an X-ray powder diffractometer and a scanning electron microscopy, two types of pure CaCO3 polymorphs (vaterite and calcite) are identified as main reaction products. Their abundance and morphology are heavily dependent on the mineralization temperature. Noticeably, spindle-shaped vaterite, which is quite different from a typical vaterite morphology (polycrystalline spherulite), forms predominantly at 333 K (approximately 98 wt%).

  10. Resonance analysis of the {sup 12}C,{sup 13}C({alpha},n) reactions and evaluation of neutron yield data of the reaction

    Energy Technology Data Exchange (ETDEWEB)

    Murata, Toru [AITEL Corp., Tokyo (Japan)

    1998-03-01

    The {sup 12}C({alpha},n){sup 15}O reaction and the {sup 13}C({alpha},n){sup 16}O reaction were analyzed with a resonance formula in the incident {alpha}-particle energy range of 1.0 to 16.0 MeV. With the obtained resonance parameters, branching ratios of the emitted neutrons to the several levels of the residual nucleus and their angular distributions were calculated to obtain the energy spectrum of emitted neutrons. Thick target neutron yield of carbon were also calculated and compared with the experimental data. (author)

  11. Composition of amino acid using carbon monoxide. Amide carbonylation reaction

    Energy Technology Data Exchange (ETDEWEB)

    Izawa, Kunisuke (Ajinomoto Co., Inc., Tokyo (Japan))

    1989-02-01

    Amide carbonylation reaction is a method to compose N-acyl-{alpha}-amino acid from aldehyde, carboxylic acid amide, and carbon monoxide in a phase and with high yield. Unlike the conventional Strecker reaction, this method does not use HCN which is in question on public pollution and does not require hydrolysis. This amide carbonylation reaction was discovered by Wakamatsu and others of Ajinomoto Co.,Ltd. Present application examples of this method are the composition of N-acetyl amino acid from the aldehyde class, the composition of N-Acyl amino acid from olefin, the composition of N-acyl or acetyl amino acid from the raw material of alcohol and the halide class, the composition of N-acyl or acetyl amino acid via the isomerization of epoxide and allyl alcohol, the composition of amino dicarboxylic acid, applying deoxidation of ring acid anhydride, the composition of N-acyl amino acid from the raw material of the amine class, the stereoselective composition of -substitution ring-{alpha}-amino acid, and the composition of amino aldehyde. 24 refs., 2 figs., 2 tabs.

  12. Efficient Diels-Alder reaction of 1,2-benzoquinones with arynes and its utility in one-pot reactions.

    Science.gov (United States)

    Kaicharla, Trinadh; Bhojgude, Sachin Suresh; Biju, Akkattu T

    2012-12-21

    A new protocol for the efficient Diels-Alder reaction of 1,2-benzoquinones with arynes is reported. The aryne generated by the fluoride-induced 1,2-elimination of 2-(trimethylsilyl)aryl triflates undergoes a facile Diels-Alder reaction with 1,2-benzoquinones, affording the dioxobenzobicyclooctadienes in moderate to excellent yields. In addition, this methodology has been applied to the one-pot synthesis of benzoquinoxalinobarrelene and naphthalene derivatives.

  13. The synthesis of PdPt/carbon paper via surface limited redox replacement reactions for oxygen reduction reaction

    CSIR Research Space (South Africa)

    Motsoeneng, RG

    2015-09-01

    Full Text Available Surface-limited redox replacement reactions using the electrochemical atomic layer deposition (EC-ALD) technique were used to synthesize PdPt bimetallic electrocatalysts on carbon paper substrate. Electrocatalysts having different Pd:Pt ratio were...

  14. kinetics of the coupled gas-iron reactions involving silicon and carbon

    African Journals Online (AJOL)

    user

    1985-09-01

    Sep 1, 1985 ... out for the system involving liquid iron containing carbon and silicon and a gas ... in content with liquid iron at. 15600C, the ... of carbon monoxide bubbles at the. Slag - metal ..... equilibrium strongly make chemical reactions.

  15. Carbon-coated magnetic palladium: applications in partial oxidation of alcohols and coupling reactions.

    Science.gov (United States)

    Magnetic carbon supported Pd catalyst has been synthesized via in situ generation of nanoferrites and incorporation of carbon from renewable cellulose via calcination; catalyst can be used for oxidation of alcohols, amination reaction and arylation of aryl halides (cross coupli...

  16. Radiation induced chemical reaction of carbon monoxide and hydrogen mixture

    International Nuclear Information System (INIS)

    Sugimoto, Shun-ichi; Nishii, Masanobu

    1985-01-01

    Previous studies of radiation induced chemical reactions of CO-H 2 mixture have revealed that the yields of oxygen containing products were larger than those of hydrocarbons. In the present study, methane was added to CO-H 2 mixture in order to increase further the yields of the oxygen containing products. The yields of most products except a few products such as formaldehyde increased with the addition of small amount of methane. Especially, the yields of trioxane and tetraoxane gave the maximum values when CO-H 2 mixture containing 1 mol% methane was irradiated. When large amounts of methane were added to the mixture, the yields of aldehydes and carboxylic acids having more than two carbon atoms increased, whereas those of trioxane and tetraoxane decreased. From the study at reaction temperature over the range of 200 to 473 K, it was found that the yields of aldehydes and carboxylic acids showed maxima at 323 K. The studies on the effects of addition of cationic scavenger (NH 3 ) and radical scavenger (O 2 ) on the products yields were also carried out on the CO-H 2 -CH 4 mixture. (author)

  17. Reaction of uranium oxides with chlorine and carbon or carbon monoxide to prepare uranium chlorides

    Energy Technology Data Exchange (ETDEWEB)

    Haas, P.A.; Lee, D.D.; Mailen, J.C.

    1991-11-01

    The preferred preparation concept of uranium metal for feed to an AVLIS uranium enrichment process requires preparation of uranium tetrachloride (UCI{sub 4}) by reacting uranium oxides (UO{sub 2}/UO{sub 3}) and chlorine (Cl{sub 2}) in a molten chloride salt medium. UO{sub 2} is a very stable metal oxide; thus, the chemical conversion requires both a chlorinating agent and a reducing agent that gives an oxide product which is much more stable than the corresponding chloride. Experimental studies in a quartz reactor of 4-cm ID have demonstrated the practically of some chemical flow sheets. Experimentation has illustrated a sequence of results concerning the chemical flow sheets. Tests with a graphite block at 850{degrees}C demonstrated rapid reactions of Cl{sub 2} and evolution of carbon dioxide (CO{sub 2}) as a product. Use of carbon monoxide (CO) as the reducing agent also gave rapid reactions of Cl{sub 2} and formation of CO{sub 2} at lower temperatures, but the reduction reactions were slower than the chlorinations. Carbon powder in the molten salt melt gave higher rates of reduction and better steady state utilization of Cl{sub 2}. Addition of UO{sub 2} feed while chlorination was in progress greatly improved the operation by avoiding the plugging effects from high UO{sub 2} concentrations and the poor Cl{sub 2} utilizations from low UO{sub 2} concentrations. An UO{sub 3} feed gave undesirable effects while a feed of UO{sub 2}-C spheres was excellent. The UO{sub 2}-C spheres also gave good rates of reaction as a fixed bed without any molten chloride salt. Results with a larger reactor and a bottom condenser for volatilized uranium show collection of condensed uranium chlorides as a loose powder and chlorine utilizations of 95--98% at high feed rates. 14 refs., 7 figs., 14 tabs.

  18. Over half a century of studying carbon-12

    Science.gov (United States)

    Kokalova Wheldon, Tzany

    2015-09-01

    Carbon-12 is one of the most studied light nuclei yet it continues to surprise and provide a rigorous testing ground for a wide range of physics, from nucleosynthesis models to theories of symmetries. This paper discusses the background motivating the investigations of 12C and summarises the recent results, with an emphasis on collective excitations and the high-energy structure together with possible future directions for this most intriguing of nuclei.

  19. On the knock-out mechanism for the 12C(P,α)9B reaction

    International Nuclear Information System (INIS)

    Hassan, M.Y.M.; Ismail, E.H.; Rabie, A.

    1978-01-01

    The mechanism of the reaction 12 C(P,α) 9 B is studied using zero range distorted wave Born approximation. The knock out mechanism is assumed to represent this reaction both in the forward and backward angles. (orig.) [de

  20. MOF-derived Cu/nanoporous carbon composite and its application for electro-catalysis of hydrogen evolution reaction

    International Nuclear Information System (INIS)

    Raoof, Jahan-Bakhsh; Hosseini, Sayed Reza; Ojani, Reza; Mandegarzad, Sakineh

    2015-01-01

    In this work, metal-organic framework Cu_3(BTC)_2 [BTC = 1,3,5-benzenetricarboxylate] (commonly known as MOF-199 or HKUST-1), is used as porous template for preparation of a Cu/nanoporous carbon composite. The MOF-derived Cu/nanoporous carbon composite (Cu/NPC composite) is synthesized by direct carbonization of the MOF-199 without any carbon precursor additive. The physical characterization of the solid catalyst is achieved by using a variety of different techniques, including XRD (X-ray powder diffraction), scanning electron microscopy, thermo-gravimetric analysis, and nitrogen physisorption measurements. The electrochemical results have shown that the Cu/NPC composite modified glassy carbon electrode (Cu/NPC/GCE) as a non-platinum electrocatalyst exhibited favorable catalytic activity for hydrogen evolution reaction, in spite of high resistance to faradic process. This behavior can be attributed to existence of Cu metal confirmed by XRD and/or high effective pore surface area (1025 m"2 g"−"1) in the Cu/NPC composite. The electron transfer coefficient and exchange current density for the Cu/NPC/GCE is calculated by Tafel plot at about 0.34 and 1.2 × 0"−"3 mAcm"−"2, respectively. - Graphical abstract: Metal organic framework-derived Cu/nanoporous carbon composite (Cu/NPC composite) was prepared by direct carbonization of MOF-199 without addition of any carbon source at 900 °C. The Cu/NPC/GCE demonstrated an excellent electrocatalytic activity towards hydrogen evolution reaction compared with bare GCE. - Highlights: • MDNPC (MOF-199 derived nanoporous carbon) is prepared by direct carbonization. • MOF-199 is utilized as a template without addition of carbon resource. • The MDNPC has a good electrocatalytic activity in hydrogen evolution reaction. • High BET surface area and hydrogen adsorption property improved catalyst activity.

  1. Synergistically enhanced activity of nitrogen-doped carbon dots/graphene composites for oxygen reduction reaction

    Science.gov (United States)

    Liu, Hui; Zhao, Qingshan; Liu, Jingyan; Ma, Xiao; Rao, Yuan; Shao, Xiaodong; Li, Zhongtao; Wu, Wenting; Ning, Hui; Wu, Mingbo

    2017-11-01

    With rapid dissociative adsorption of oxygen, nitrogen-doped carbon nanomaterials have been demonstrated to be efficient alternative catalysts for oxygen reduction reaction (ORR) in fuel cells. Herein, we developed a mild hydrothermal strategy to construct nitrogen-doped carbon dots/graphene (NCDs-NG) composites towards ORR. Carbon dots (CDs) were derived from petroleum coke via acid oxidation while graphene oxide (GO) was obtained from graphite by modified Hummer's method. Graphene was employed as a conductive substrate to disperse CDs during hydrothermal reducing reaction while ammonia was utilized as N source to dope both graphene and CDs. The synergistic effects, i.e. CDs as pillars for graphene and catalytic sites for ORR, the high conductivity of graphene, the quick O2 adsorption on doped pyridinic nitrogen endow the NCDs-NG composites with enhanced ORR catalytic performance in alkaline electrolyte. The onset potential of -95 mV and kinetic current density of 12.7 mA cm-2 at -0.7 V (vs. Ag/AgCl) can be compared to those of the commercial 20 wt% Pt/C catalyst. The electron transfer number is about 3.9, revealing a four-electron pathway for ORR. The optimal NCDs-NG catalyst shows superior durability and methanol tolerance than 20 wt% Pt/C. This work demonstrates a feasible and effective strategy to prepare metal-free efficient ORR electrocatalysts for fuel cell applications.

  2. High-Throughput Screening of the Asymmetric Decarboxylative Alkylation Reaction of Enolate-Stabilized Enol Carbonates

    KAUST Repository

    Stoltz, Brian

    2010-06-14

    The use of high-throughput screening allowed for the optimization of reaction conditions for the palladium-catalyzed asymmetric decarboxylative alkylation reaction of enolate-stabilized enol carbonates. Changing to a non-polar reaction solvent and to an electron-deficient PHOX derivative as ligand from our standard reaction conditions improved the enantioselectivity for the alkylation of a ketal-protected,1,3-diketone-derived enol carbonate from 28% ee to 84% ee. Similar improvements in enantioselectivity were seen for a β-keto-ester derived- and an α-phenyl cyclohexanone-derived enol carbonate.

  3. High-Throughput Screening of the Asymmetric Decarboxylative Alkylation Reaction of Enolate-Stabilized Enol Carbonates

    KAUST Repository

    Stoltz, Brian; McDougal, Nolan; Virgil, Scott

    2010-01-01

    The use of high-throughput screening allowed for the optimization of reaction conditions for the palladium-catalyzed asymmetric decarboxylative alkylation reaction of enolate-stabilized enol carbonates. Changing to a non-polar reaction solvent and to an electron-deficient PHOX derivative as ligand from our standard reaction conditions improved the enantioselectivity for the alkylation of a ketal-protected,1,3-diketone-derived enol carbonate from 28% ee to 84% ee. Similar improvements in enantioselectivity were seen for a β-keto-ester derived- and an α-phenyl cyclohexanone-derived enol carbonate.

  4. BOREAS TGB-12 Soil Carbon Data over the NSA

    Science.gov (United States)

    Trumbore, Susan; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor); Harden, Jennifer; Sundquist, Eric; Winston, Greg

    2000-01-01

    The BOREAS TGB-12 team made measurements of soil carbon inventories, carbon concentration in soil gases, and rates of soil respiration at several sites to estimate the rates of carbon accumulation and turnover in each of the major vegetation types. TGB-12 data sets include soil properties at tower and selected auxiliary sites in the BOREAS NSA and data on the seasonal variations in the radiocarbon content of CO2 in the soil atmosphere at NSA tower sites. The sampling strategies for soils were designed to take advantage of local fire chronosequences, so that the accumulation of C in areas of moss regrowth could be determined. These data are used to calculate the inventory of C and N in moss and mineral soil layers at NSA sites and to determine the rates of input and turnover (using both accumulation since the last stand-killing fire and radiocarbon data). This data set includes physical parameters needed to determine carbon and nitrogen inventory in soils. The data were collected discontinuously from August 1993 to July 1996. The data are stored in tabular ASCII files.

  5. Reaction 12C(16O,α)24Mg leading to nuclear molecular resonances

    International Nuclear Information System (INIS)

    Nagatani, K.; Shimoda, T.; Tanner, D.; Tribble, R.; Yamaya, T.

    1979-01-01

    The reactions 12 C( 16 O,α) 24 Mg and 13 C( 16 O,α) 25 Mg were investigated at an incident energy of 145 MeV. In the reaction with the 12 C target, broad peaks are observed at forward angles which correspond to the molecular resonance states of the 12 C+ 12 C system, while the spectra with 13 C target show only a smooth continuum

  6. Dilepton spectroscopy at intermediate energies; the carbon - carbon reaction at 1 GeV/A

    International Nuclear Information System (INIS)

    Prunet, M.

    1995-01-01

    The Physics context of this work is heavy ion collisions at relativistic energies where di-electron provide informations on the produced hot and dense nuclear matter. The experiment is performed by the DiLepton Spectrometer (DLS) Collaboration at the Lawrence Berkeley's Bevalac. After a description of the apparatus, we review the whole program and the main results so far obtained: first evidence of a significant di-electron signal at energies above 1 GeV/A; improvement of the understanding of di-electron production (electromagnetic decays of hadrons, π + π - annihilation and hadronic Bremsstrahlung). The results of p-p, p-d reactions from 1 to 4.9 GeV/A show that hadronic Bremsstrahlung (pp, pn) should be reformulated. Our analysis, optimized on the reaction Carbon-Carbon at 1 GeV/A, has been applied to α-Ca and d-Ca. We have developed two main aspects: improvement of the time resolution (500 ps) in order to eliminate all of the protons. Improvement of the space resolution (300 μ) for better mass resolution, in particular in the ρ region. We obtain the cross section of di-electron production as a function of mass, transverse momentum and rapidity from the C-C, α-Ca and d-Ca reactions at 1 GeV/A. We also compare the cross section for all of the measured systems at 1 GeV/A, including Ca-Ca, and we show a (ApAt) α dependence with α ≅ 1.1. A study of the associated multiplicity has also been performed. Nevertheless, the limited acceptance of the DLS and its poor mass resolution to identify the ρ, ω vector mesons, do not allow to conclude on hadron behaviour in nuclear matter. This point is one of the main goal of the HADES project at GSI (Darmstadt), which we give a brief description of the main features. (authors). 60 refs

  7. Determination of reaction cross sections with the aid of α decay in the 12C, 14C + 209Bl reactions

    International Nuclear Information System (INIS)

    Hick, H.

    1980-01-01

    For the reactions 14 C + 209 Bi and 12 C + 209 Bi excitation functions at energies in the range between 57 MeV and 76 MeV are measured. Radiative capture and particle evaporation cross sections were determined by means of α-spectroscopy, and fission cross sections were determined by the measurement of the γ-radiation after the β-decay of the fission products. For the radiative capture for the reaction 14 C + 209 Bi upper limits for the cross section from 21 nbarn to 178 nbarn in the energy interval 61-74 MeV were determined. The fission cross sections were 80 +- 30 mbarn at 490 +- 200 mbarn at 76 MeV. For the reaction 12 C + 209 Bi three new α-lines were found. They were due to the slope at their excitation functions assigned to the decay of isomeric states of following nuclei: 219 Ac Esub(α) = 9419 +- 4 keV Tsub(1/2) = 830 +- 100/μsec, 218 Ac Esub(α) = 9271 +- 4 keV Tsub(1/2) = 810 +- 70/μsec, 217 Ac Eα = 9730 +- 5 keV Tsub(1/2) = 970 +- 190/μsec. For the reactions respectively 12 C + 209 Bi calculations using the statistical model code Grogi of J. Gilat are performed. The calculated branchings of the evaporation channels were compared with the experiment. (orig./HSI) [de

  8. Biogenic Methane Generation Potential in the Eastern Nankai Trough, Japan: Effect of Reaction Temperature and Total Organic Carbon

    Science.gov (United States)

    Aung, T. T.; Fujii, T.; Amo, M.; Suzuki, K.

    2017-12-01

    Understanding potential of methane flux from the Pleistocene fore-arc basin filled turbiditic sedimentary formation along the eastern Nankai Trough is important in the quantitative assessment of gas hydrate resources. We considered generated methane could exist in sedimentary basin in the forms of three major components, and those are methane in methane hydrate, free gas and methane dissolved in water. Generation of biomethane strongly depends on microbe activity and microbes in turn survive in diverse range of temperature, salinity and pH. This study aims to understand effect of reaction temperature and total organic carbon on generation of biomethane and its components. Biomarker analysis and cultural experiment results of the core samples from the eastern Nankai Trough reveal that methane generation rate gets peak at various temperature ranging12.5°to 35°. Simulation study of biomethane generation was made using commercial basin scale simulator, PetroMod, with different reaction temperature and total organic carbon to predict how these effect on generation of biomethane. Reaction model is set by Gaussian distribution with constant hydrogen index and standard deviation of 1. Series of simulation cases with peak reaction temperature ranging 12.5°to 35° and total organic carbon of 0.6% to 3% were conducted and analyzed. Simulation results show that linear decrease in generation potential while increasing reaction temperature. But decreasing amount becomes larger in the model with higher total organic carbon. At higher reaction temperatures, >30°, extremely low generation potential was found. This is due to the fact that the source formation modeled is less than 1 km in thickness and most of formation do not reach temperature more than 30°. In terms of the components, methane in methane hydrate and free methane increase with increasing TOC. Drastic increase in free methane was observed in the model with 3% of TOC. Methane amount dissolved in water shows almost

  9. Coal chemistry. 8. Reactions of tetralin with coal and with some carbon-14-containing model compounds

    International Nuclear Information System (INIS)

    Collins, C.J.; Raaen, V.F.; Benjamin, B.M.; Maupin, P.H.; Roark, W.H.

    1979-01-01

    When coal was treated with tetralin-l- 14 C at 400 0 C, small yields of α- and β-methylnaphthalenes- 14 C were observed. In order to determine the mechanism of the reaction, tetralin was heated with 14 C-labeled 1,3-diphenylpropanes (1), with 1,3-diphenylpropene (2), and with 14 C-labeled phenetoles (3). In each case methylnaphthalenes were observed, and the origins of the methyl groups were determined with carbon-14. In addition to the methylnaphthalenes, 1 and 2 also yielded toluene and ethylbenzene (after 19 h), whereas phenetole-β- 14 C (3-β- 14 C) yielded toluene (unlabeled) plus ethyl- 14 C-benzene, benzene, phenol, and a mixture of α- and β-ethyl- 14 C-naphthalenes. Crossover experiments with labeled phenetole and unlabeled ethyl p-tolyl ether proved the intramolecularity of the reaction phenetole → toluene + ethylbenzene, thus illustrating a 1,2-phenyl shift from oxygen to carbon

  10. The 12C+12C → 8Begs+16Ogs reaction at Ecm=27 to 36 MeV

    International Nuclear Information System (INIS)

    Aliotta, M.; Lattuada, M.; Spitaleri, C.

    1996-01-01

    The 12 C + 12 C → 8 Be gs + 16 O gs reaction has been experimentally investigated at c.m. energies between 27 and 36 MeV. A resonance is present at 32.5 MeV, i.e. at the same energy of the resonance previously observed [1] in the 12 C(0 + 2 ) + 12 C(0 + 2 ) exit channel, but its width is about three times narrower. Moreover the data indicate an enhancement of the cross section at a c.m. energy close to 29 MeV. These results are discussed and compared to the predictions of the Band Crossing Model obtained for different exit channels of the 12 C + 12 C reaction. (orig.)

  11. Reaction velocity of sodium hydration in humid air and sodium carbonation in humid carbon dioxide atmosphere. Fundamental study on sodium carbonate process in FBR bulk sodium coolant disposal technology

    International Nuclear Information System (INIS)

    Tadokoro, Yutaka; Yoshida, Eiichi

    1999-11-01

    A sodium carbonate processing method, which changes sodium to sodium carbonate and/or sodium bicarbonate by humid carbon dioxide, has been examined and about to be applied to large test loops dismantling. However, that the basic data regarding the progress of the reaction is insufficient on the other hand, is a present condition. The present report therefore aims at presenting basic data regarding the reaction velocity of sodium hydration in humid air and sodium carbonation in humid carbon dioxide atmosphere, and observing the reaction progress, for the application to large test loops dismantling. The test result is summarized as follows. (1) Although the reaction velocity of sodium varied with sodium specimen sizes and velocity measurement methods, the reaction velocity of sodium hydration was in about 0.16 ∼ 0.34 mmh -1 (0.016 ∼ 0.033g cm -2 h -1 , 6.8x10 -4 ∼ 1.4x10 -3 mol cm -2 h -1 ) and that of sodium carbonation was in about 0.16 ∼ 0.27mmh -1 (0.016 ∼ 0.023g cm -2 h -1 , 6.8x10 -4 ∼ 1.1x10 -3 mol cm -2 h -1 ) (26 ∼ 31degC, RH 100%). (2) The reaction velocity of sodium in carbon dioxide atmosphere was greatly affected by vapor partial pressure (absolutely humidity). And the velocity was estimated in 0.08 ∼ 0.12mmh -1 (0.008 ∼ 0.012g cm -2 h -1 , 3.4x10 -4 ∼ 5.2x10 -4 mol cm -2 h -1 ) in the carbon dioxide atmosphere, whose temperature of 20degC and relative humidity of 80% are assumed real sodium carbonate process condition. (3) By the X-ray diffraction method, NaOH was found in humid air reaction product. Na 2 CO 3 , NaHCO 3 were found in carbon dioxide atmosphere reaction product. It was considered that Sodium changes to NaOH, and subsequently to NaHCO 3 through Na 2 CO 3 . (4) For the application to large test loops dismantling, it is considered possible to change sodium to a target amount of sodium carbonate (or sodium bicarbonate) by setting up gas supply quantity and also processing time appropriately according to the surface area

  12. Integral measurement of the $^{12}$C(n,p)$^{12}$B reaction up to 10 GeV

    CERN Document Server

    Žugec, P; Bosnar, D; Ventura, A; Mengoni, A; Altstadt, S; Andrzejewski, J; Audouin, L; Barbagallo, M; Bécares, V; Bečvář, F; Belloni, F; Berthoumieux, E; Billowes, J; Boccone, V; Brugger, M; Calviani, M; Calviño, F; Cano-Ott, D; Carrapiço, C; Cerutti, F; Chiaveri, E; Chin, M; Cortés, G; Cortés-Giraldo, M.A; Cosentino, L; Diakaki, M; Domingo-Pardo, C; Dressler, R; Duran, I; Eleftheriadis, C; Ferrari, A; Finocchiaro, P; Fraval, K; Ganesan, S; García, A R; Giubrone, G; Gómez-Hornillos, M B; Gonçalves, I F; González-Romero, E; Griesmayer, E; Guerrero, C; Gunsing, F; Gurusamy, P; Heinitz, S; Jenkins, D G; Jericha, E; Käppeler, F; Karadimos, D; Kivel, N; Kokkoris, M; Krtička, M; Kroll, J; Langer, C; Lederer, C; Leeb, H; Leong, L S; Meo, S Lo; Losito, R; Manousos, A; Marganiec, J; Martínez, T; Massimi, C; Mastinu, P; Mastromarco, M; Mendoza, E; Milazzo, P M; Mingrone, F; Mirea, M; Mondalaers, W; Musumarra, A; Paradela, C; Pavlik, A; Perkowski, J; Plompen, A; Praena, J; Quesada, J; Rauscher, T; Reifarth, R; Riego, A; Roman, F; Rubbia, C; Sarmento, R; Saxena, A; Schillebeeckx, P; Schmidt, S; Schumann, D; Tagliente, G; Tain, J L; Tarrío, D; Tassan-Got, L; Tsinganis, A; Valenta, S; Vannini, G; Variale, V; Vaz, P; Versaci, R; Vermeulen, M J; Vlachoudis, V; Vlastou, R; Wallner, A; Ware, T; Weigand, M; Weiß, C; Wright, T

    2016-01-01

    The integral measurement of the $^{12}$C(n,p)$^{12}$B reaction was performed at the neutron time of flight facility n_TOF at CERN. The total number of $^{12}$B nuclei produced per neutron pulse of the n_TOF beam was determined using the activation technique in combination with a time of flight technique. The cross section is integrated over the n_TOF neutron energy spectrum from reaction threshold at 13.6 MeV to 10 GeV. Having been measured up to 1 GeV on basis of the $^{235}$U(n,f) reaction, the neutron energy spectrum above 200 MeV has been reevaluated due to the recent extension of the cross section reference for this particular reaction, which is otherwise considered a standard up to 200 MeV. The results from the dedicated GEANT4 simulations have been used to evaluate the neutron flux from 1 GeV up to 10 GeV. The experimental results related to the $^{12}$C(n,p)$^{12}$B reaction are compared with the evaluated cross sections from major libraries and with the predictions of different GEANT4 models, which m...

  13. Contribution to the study of reactions induced by a low-energy He3 beam on a C12 target

    International Nuclear Information System (INIS)

    Schapira, Jean-Paul

    1965-01-01

    This research thesis reports the study concerning which reaction mode will better describe a nucleus in which the excitation energy is between two extremes. Due to experimental considerations and abilities, this study focuses on light target nuclei and carbon 12. The author describes experimental techniques used for angular distributions (targets, detection system), describes the experimental techniques for activation experiments (experimental set-up, targets, measurement of relative efficient cross section, result analysis, measurement of absolute efficient cross section). The author discusses the experimental results (excitation functions and angular distributions) and the interpretation of elastic scattering results (theoretical background, computation approach, analysis of elastic scattering) and the results of the C 12 (He 3 , α)C 11 reaction [fr

  14. Ozonation of 1,2-dihydroxybenzene in the presence of activated carbon.

    Science.gov (United States)

    Zaror, C; Soto, G; Valdés, H; Mansilla, H

    2001-01-01

    This work aims at obtaining experimental data on ozonation of 1,2-dihydroxybenzene (DHB) in the presence of activated carbon, with a view to assessing possible changes in its surface chemical structure and adsorption capacity. Experiments were conducted in a 0.5 L reactor, loaded with 2 g Filtrasorb 400 granular activated carbon, and 1-5 mM DHB aqueous solution at pH 2-8. Ozone gas was generated with an Ozocav generator, and fed into the reactor for a given exposure time, in the range 0.5-240 min, at 25 degrees C and 1 atm. After each run, liquid and activated carbon samples were taken for chemical assays. Soluble organic groups present on the active carbon surface were desorbed and analysed by GC-MS and HPLC. Activated carbon chemical surface properties were analysed using TPD, FT-IR, and XPS techniques. Reactions between ozone and adsorbed DHB were shown to be fast, leading to formation of C-6, C-4 and C-2 by-products. Oxygenated surface groups, particularly, COOH and C = O, increased as a result of ozonation.

  15. Optical excitation of carbon nanotubes drives stoichiometric reaction with diazonium salts

    Science.gov (United States)

    Powell, Lyndsey; Piao, Yanmei; Wang, Yuhuang; YuHuang Wang Research Group Team

    Covalent chemistry is known to lack the precision required to tailor the physical properties of carbon nanostructures. Here we show that, for the first time, light can be used to drive a typically inefficient reaction with single-walled carbon nanotubes in a more stoichiometric fashion. Specifically, our experimental results suggest that light can enhance the reaction rate of diazonium salt with carbon nanotubes by as much as 35-fold, making possible stoichiometric control of the covalent bonding of a functional group to the sp2 carbon lattice. This light-controlled reaction paves the way for the possibility of highly selective and precise chemistry on single-walled carbon nanotubes and other graphitic nanostructures.

  16. Insights into the importance of oxygen functional groups in carbon reactions with oxygen containing gases

    International Nuclear Information System (INIS)

    John Zhu, Max Lu

    2005-01-01

    The role of pore structure of carbon in carbon-related adsorptions and reactions has been extensively investigated. However the studies on the role of surface chemistry of carbon are limited. In this paper, we present the importance of oxygen functional groups in carbon reactions with oxygen-containing gases. It is found that there is a good correlation between the electronic structures and reactivities of carbon edge sites. Zigzag sites are more active in oxygen adsorption because of the unpaired electrons and armchair sites are less active in oxygen adsorption due to the triple character. However, the desorption of semi-quinone oxygen from zigzag sites needs a bond energy ca. 30% higher than that of o-quinone oxygen from armchair edge sites. CO 2 and H 2 O adsorb on carbon surface much less favorably than O 2 . H 2 O is first physically adsorbed on the virgin graphite surface followed by chemisorption through oxygen atom approaching the carbon edge site and the movements of two hydrogen atoms to produce H 2 . The adsorption mechanism of H 2 O is different from that for CO 2 , but the final result is quite similar, i.e. producing only semi-quinone oxygen. Based upon the above studies, a new generalized mechanism, as shown in Fig. 1, is developed and can account for all the important kinetic phenomena of carbon-gas reactions. The key point is that in CO 2 /H 2 O-carbon reaction only semi-quinone formed; while, in O 2 -carbon reaction, semi-quinone, o-quinone (at lower pressure), and off-plane epoxy oxygen (at relatively higher pressure) can be formed. This is the main reason for the different reaction kinetics of O 2 -carbon reaction and CO 2 /H 2 O-carbon reactions as observed experimentally. The oxygen functional groups of carbon can be characterized by XPS, PZC (point of zero charge), IEP (isoelectric point) and TPD (temperature-programmed desorption), which were used in our previous studies. We treated the carbon surface with different acids, finding that HNO 3

  17. Effect of compound nuclear reaction mechanism in 12C(6Li,d) reaction at sub-Coulomb energy

    Science.gov (United States)

    Mondal, Ashok; Adhikari, S.; Basu, C.

    2017-09-01

    The angular distribution of the 12C(6Li,d) reaction populating the 6.92 and 7.12 MeV states of 16O at sub-Coulomb energy (Ecm=3 MeV) are analysed in the framework of the Distorted Wave Born Approximation (DWBA). Recent results on excitation function measurements and backward angle angular distributions derive ANC for both the states on the basis of an alpha transfer mechanism. In the present work, we show that considering both forward and backward angle data in the analysis, the 7.12 MeV state at sub-Coulomb energy is populated from Compound nuclear process rather than transfer process. The 6.92 MeV state is however produced from direct reaction mechanism.

  18. High spin levels populated in multinucleon transfer reaction with 480 MeV 12C

    International Nuclear Information System (INIS)

    Kraus, L.; Boucenna, A.; Linck, I.

    1988-01-01

    Two- and three-nucleon stripping reactions induced by 480 MeV 12 C have been studied on 12 C, 16 O, 28 Si, 40 Ca and 54 Fe target nuclei. Discrete levels are fed with cross sections up to 1 mb/sr for d-transfer reactions and one order and two orders of magnitude less for 2p- and 3 He-transfer reactions, respectively. These reactions preferentially populate high spin states with stretched configurations. Several spin assignments were known from transfer reactions induced by lighter projectiles at incident energies well above the Coulomb barrier. In the case of two-nucleon transfer reactions, the energy of these states is well reproduced by crude shell model calculations. Such estimates are of use in proposing spins of newly observed states especially as the shapes of the measured angular distributions are independent of the final spin of the residual nucleus

  19. Enhanced interfacial properties of carbon fiber composites via aryl diazonium reaction “on water”

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yuwei [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); Meng, Linghui [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Fan, Liquan [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); Ma, Lichun; Qi, Meiwei; Yu, Jiali [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Huang, Yudong, E-mail: ydhuang.hit1@yahoo.com.cn [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China)

    2014-10-15

    Highlights: • Carbon fibers are grafted with phenyl amine group via aryl diazonium reaction. • Interfacial shear strength of the carbon fibers increases by 73%. • Tensile strength of the carbon fibers does not decrease distinctly. • Using water as the reaction medium can avoid pollution from organic solvents. • Grafting via aryl diazonium reaction in one step can improve modification efficiency. - Abstract: Polyacrylonitrile-based carbon fibers were functionalized with phenyl amine group via aryl diazonium reaction “on water” to improve their interfacial bonding with resin matrix. Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy were employed to characterize ordered degree, functional groups, chemical states and morphology of carbon fiber surface, respectively. The results showed that phenyl amine groups were grafted on the fiber surface successfully. Mechanical property test results indicated that the aryl diazonium reaction in this paper could improve the interfacial shear strength by 73%, while the tensile strength was down very slightly. Hence aryl diazonium reaction “on water” could be a facile green platform to functionalize carbon fibers for many interesting applications.

  20. Enhanced interfacial properties of carbon fiber composites via aryl diazonium reaction “on water”

    International Nuclear Information System (INIS)

    Wang, Yuwei; Meng, Linghui; Fan, Liquan; Ma, Lichun; Qi, Meiwei; Yu, Jiali; Huang, Yudong

    2014-01-01

    Highlights: • Carbon fibers are grafted with phenyl amine group via aryl diazonium reaction. • Interfacial shear strength of the carbon fibers increases by 73%. • Tensile strength of the carbon fibers does not decrease distinctly. • Using water as the reaction medium can avoid pollution from organic solvents. • Grafting via aryl diazonium reaction in one step can improve modification efficiency. - Abstract: Polyacrylonitrile-based carbon fibers were functionalized with phenyl amine group via aryl diazonium reaction “on water” to improve their interfacial bonding with resin matrix. Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy were employed to characterize ordered degree, functional groups, chemical states and morphology of carbon fiber surface, respectively. The results showed that phenyl amine groups were grafted on the fiber surface successfully. Mechanical property test results indicated that the aryl diazonium reaction in this paper could improve the interfacial shear strength by 73%, while the tensile strength was down very slightly. Hence aryl diazonium reaction “on water” could be a facile green platform to functionalize carbon fibers for many interesting applications

  1. Radical scavenging reaction kinetics with multiwalled carbon nanotubes

    NARCIS (Netherlands)

    Tsuruoka, Shuji; Matsumoto, Hidetoshi; Koyama, Kenichi; Akiba, Eiji; Yanagisawa, Takashi; Cassee, Flemming R.; Saito, Naoto; Usui, Yuki; Kobayashi, Shinsuke; Porter, Dale W.; Castranova, Vincent; Endo, Morinobu

    2015-01-01

    Progress in the development of carbon nanotubes (CNTs) has stimulated great interest among industries providing new applications. Meanwhile, toxicological evaluations on nanomaterials are advancing leading to a predictive exposure limit for CNTs, which implies the possibility of designing safer

  2. Growth and Destruction of PAH Molecules in Reactions with Carbon Atoms

    Energy Technology Data Exchange (ETDEWEB)

    Krasnokutski, Serge A.; Huisken, Friedrich; Jäger, Cornelia; Henning, Thomas [Laboratory Astrophysics Group of the Max Planck Institute for Astronomy at the Friedrich Schiller University Jena, Helmholtzweg 3, D-07743 Jena (Germany)

    2017-02-10

    A very high abundance of atomic carbon in the interstellar medium (ISM), and the high reactivity of these species toward different hydrocarbon molecules including benzene, raise questions regarding the stability of polycyclic aromatic hydrocarbon (PAH) molecules in space. To test the efficiency of destruction of PAH molecules via reactions with atomic carbon, we performed a set of laboratory and computational studies of the reactions of naphthalene, anthracene, and coronene molecules with carbon atoms in the ground state. The reactions were investigated in liquid helium droplets at T = 0.37 K and by quantum chemical computations. Our studies suggest that all small and all large catacondensed PAHs react barrierlessly with atomic carbon, and therefore should be efficiently destroyed by such reactions in a broad temperature range. At the same time, large compact pericondensed PAHs should be more inert toward such a reaction. In addition, taking into account their higher photostability, much higher abundances of pericondensed PAHs should be expected in various astrophysical environments. The barrierless reactions between carbon atoms and small PAHs also suggest that, in the ISM, these reactions could lead to the bottom-up formation of PAH molecules.

  3. Somewhere beyond the sea? The oceanic - carbon dioxide - reactions

    Science.gov (United States)

    Meisinger, Philipp; Wittlich, Christian

    2014-05-01

    In correlation to climate change and CO2 emission different campaigns highlight the importance of forests and trees to regulate the concentration of carbon dioxide in the earths' atmosphere. Seeing millions of square miles of rainforest cut down every day, this is truly a valid point. Nevertheless, we often tend to forget what scientists like Spokes try to raise awareness for: The oceans - and foremost deep sea sections - resemble the second biggest deposit of carbon dioxide. Here carbon is mainly found in form of carbonate and hydrogen carbonate. The carbonates are needed by corals and other sea organisms to maintain their skeletal structure and thereby to remain vital. To raise awareness for the protection of this fragile ecosystem in schools is part of our approach. Awareness is achieved best through understanding. Therefore, our approach is a hands-on activity that aims at showing students how the carbon dioxide absorption changes in relation to the water temperature - in times of global warming a truly sensitive topic. The students use standard syringes filled with water (25 ml) at different temperatures (i.e. 10°C, 20°C, 40°C). Through a connector students inject carbon dioxide (25ml) into the different samples. After a fixed period of time, students can read of the remaining amount of carbon dioxide in relation to the given water temperature. Just as with every scientific project, students need to closely monitor their experiments and alter their setups (e.g. water temperature or acidity) according to their initial planning. A digital template (Excel-based) supports the analysis of students' experiments. Overview: What: hands-on, minds -on activity using standard syringes to exemplify carbon dioxide absorption in relation to the water temperature (Le Chatelier's principle) For whom: adjustable from German form 11-13 (age: 16-19 years) Time: depending on the prior knowledge 45-60 min. Sources (extract): Spokes, L.: Wie Ozeane CO2 aufnehmen. Environmental

  4. Reaction of phosphorus ylides with carbonyl compounds in supercritical carbon dioxide

    International Nuclear Information System (INIS)

    Jeong, Kyung Il; Kim, Hak Do; Shim, Jae Jin; Ra, Choon Sup

    2004-01-01

    The condensation reaction of (benzylene)triphenylphosphoranes with carbonyl compounds in supercritical carbon dioxide was examined. Reactions of (benzylene)phosphoranes (ca. 1 mmol) with several benzaldehydes in a supercritical carbon dioxide (80 .deg. C, 2,000 psi) containing THF entrainer (5%) in a 24 mL reactor proceed smoothly to yield olefination products in fairly good to excellent yields but slower, compared to reactions in a conventional THF solvent. Generally, phosphoranes that are not substituted with a nitro group show more (Z)-selective reactions with aromatic aldehydes under scCO 2 condition than in THF. The reaction of (benzylene)triphenylphosphosphoranes with 4-t-butylcyclohexanone gave the corresponding olefin compounds with a low conversion under both the supercritical carbon dioxide and the organic THF solvent. Our preliminary study showed the Wittig reaction carries out smoothly in supercritical carbon dioxide medium and also a possible tunability of this reaction pathway by adding a entrainer. The results would be useful for devising a novel process for the environmentally friendly Wittig reaction

  5. Reaction of phosphorus ylides with carbonyl compounds in supercritical carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Kyung Il; Kim, Hak Do; Shim, Jae Jin; Ra, Choon Sup [Yeungnam Univ., Gyongsan (Korea, Republic of)

    2004-02-15

    The condensation reaction of (benzylene)triphenylphosphoranes with carbonyl compounds in supercritical carbon dioxide was examined. Reactions of (benzylene)phosphoranes (ca. 1 mmol) with several benzaldehydes in a supercritical carbon dioxide (80 .deg. C, 2,000 psi) containing THF entrainer (5%) in a 24 mL reactor proceed smoothly to yield olefination products in fairly good to excellent yields but slower, compared to reactions in a conventional THF solvent. Generally, phosphoranes that are not substituted with a nitro group show more (Z)-selective reactions with aromatic aldehydes under scCO{sub 2} condition than in THF. The reaction of (benzylene)triphenylphosphosphoranes with 4-t-butylcyclohexanone gave the corresponding olefin compounds with a low conversion under both the supercritical carbon dioxide and the organic THF solvent. Our preliminary study showed the Wittig reaction carries out smoothly in supercritical carbon dioxide medium and also a possible tunability of this reaction pathway by adding a entrainer. The results would be useful for devising a novel process for the environmentally friendly Wittig reaction.

  6. Carbon-13 Labeling Used to Probe Cure and Degradation Reactions of High- Temperature Polymers

    Science.gov (United States)

    Meador, Mary Ann B.; Johnston, J. Christopher

    1998-01-01

    High-temperature, crosslinked polyimides are typically insoluble, intractible materials. Consequently, in these systems it has been difficult to follow high-temperature curing or long-term degradation reactions on a molecular level. Selective labeling of the polymers with carbon-13, coupled with solid nuclear magnetic resonance spectrometry (NMR), enables these reactions to be followed. We successfully employed this technique to provide insight into both curing and degradation reactions of PMR-15, a polymer matrix resin used extensively in aircraft engine applications.

  7. Observation of Λ-hypernuclei in the reaction 12C(π+,K+)/sub Λ/12C

    International Nuclear Information System (INIS)

    Milner, E.C.

    1985-12-01

    The observation of Λ-hypernuclear levels in /sub Λ/ 12 C by associated production through the (π + ,K + ) reaction is reported. Spectrometers used in the measurements are discussed. The /sub Λ/ 12 C excitation energy spectra were recorded at laboratory scattering angles of 5.6 0 , 10.3 0 , and 15.2 0 . The spectra show two major peaks - one attributed to the ground state, and one about 11 MeV higher in excitation. The peak near 11 MeV excitation energy is believed to be almost entirely composed of a multiplet of three J/sup π/ = 2 + states. Relativistic DWBA calculations imply support for the expectation that higher spin states are preferentially populated in the (π + ,K + ) reaction, compared to the (K - ,π - ) reaction in which lower spin states are excited. 29 refs., 40 figs

  8. Observation of. lambda. -hypernuclei in the reaction /sup 12/C(. pi. /sup +/,K/sup +/)/sub. lambda. //sup 12/C

    Energy Technology Data Exchange (ETDEWEB)

    Milner, E.C.

    1985-12-01

    The observation of ..lambda..-hypernuclear levels in /sub ..lambda..//sup 12/C by associated production through the (..pi../sup +/,K/sup +/) reaction is reported. Spectrometers used in the measurements are discussed. The /sub ..lambda..//sup 12/C excitation energy spectra were recorded at laboratory scattering angles of 5.6/sup 0/, 10.3/sup 0/, and 15.2/sup 0/. The spectra show two major peaks - one attributed to the ground state, and one about 11 MeV higher in excitation. The peak near 11 MeV excitation energy is believed to be almost entirely composed of a multiplet of three J/sup ..pi../ = 2/sup +/ states. Relativistic DWBA calculations imply support for the expectation that higher spin states are preferentially populated in the (..pi../sup +/,K/sup +/) reaction, compared to the (K/sup -/,..pi../sup -/) reaction in which lower spin states are excited. 29 refs., 40 figs.

  9. A Small-Scale Capsule Test for Investigating the Sodium-Carbon Dioxide Reaction

    International Nuclear Information System (INIS)

    Kim, B. H.; Choi, J. H.; Suk, S. D.; Kim, J. M.; Choi, B. H.; Kim, B. H.; Hahn, D. H.

    2007-01-01

    The utilization of modular sodium-to-supercritical CO 2 heat exchangers may yield significant improvements for an overall plant energy utilization. The consequences of a failure of the sodium CO 2 heat exchanger boundary, however, would involve the blowdown and intermixing of high-pressure CO 2 in a sodium pool, causing a pressurization which may threaten the structural integrity of the heat exchanger. Available data seems to indicate that the chemical reaction between sodium and CO 2 would likely produce sodium oxides, sodium carbonate, carbon and carbon monoxide. Information on the kinetics of the sodium-CO 2 reaction is virtually non-existent

  10. A kinetic study of the reaction of water vapor and carbon dioxide on uranium

    International Nuclear Information System (INIS)

    Santon, J.P.

    1964-09-01

    The kinetic study of the reaction of water vapour and carbon dioxide with uranium has been performed by thermogravimetric methods at temperatures between 160 and 410 deg G in the first case, 350 and 1050 deg C in the second: Three sorts of uranium specimens were used: uranium powder, thin evaporated films, and small spheres obtained from a plasma furnace. The experimental results led in the case of water vapour, to a linear rate of reaction controlled by diffusion at the lower temperatures, and by a surface reaction at the upper ones. In the case of carbon dioxide, a parabolic law has been found, controlled by diffusional processes. (author) [fr

  11. Geometrical aspects of reaction cross sections for 3He, 4He and 12C projectiles

    International Nuclear Information System (INIS)

    Ingemarsson, A.; Lantz, M.

    2003-04-01

    A black-disc model combined with accurate matter densities has been used for an investigation of reaction cross sections for 3 He, 4 He and 12 C projectiles. A simple relation is derived between the energy dependence of the reaction cross sections and the strength of the nucleon-nucleon interaction. A comparison is also made of the reaction cross sections for 3 He and 4 He for six different nuclei 12 C, 16 O, 40 Ca, 58,60 Ni and 208 Pb

  12. Cavitation-induced reactions in high-pressure carbon dioxide

    NARCIS (Netherlands)

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

    2002-01-01

    The feasibility of ultrasound-induced in situ radical formation in liquid carbon dioxide was demonstrated. The required threshold pressure for cavitation could be exceeded at a relatively low acoustic intensity, as the high vapor pressure of CO2 counteracts the hydrostatic pressure. With the use of

  13. Modeling the mechanism of glycosylation reactions between ethanol, 1,2-ethanediol and methoxymethanol.

    Science.gov (United States)

    Azofra, Luis Miguel; Alkorta, Ibon; Toro-Labbé, Alejandro; Elguero, José

    2013-09-07

    The mechanism of the S(N)2 model glycosylation reaction between ethanol, 1,2-ethanediol and methoxymethanol has been studied theoretically at the B3LYP/6-311+G(d,p) computational level. Three different types of reactions have been explored: (i) the exchange of hydroxyl groups between these model systems; (ii) the basic catalysis reactions by combination of the substrates as glycosyl donors (neutral species) and acceptors (enolate species); and (iii) the effect on the reaction profile of an explicit H2O molecule in the reactions considered in (ii). The reaction force, the electronic chemical potential and the reaction electronic flux have been characterized for the reaction path in each case. Energy calculations show that methoxymethanol is the worst glycosyl donor model among the ones studied here, while 1,2-ethanediol is the best, having the lowest activation barrier of 74.7 kJ mol(-1) for the reaction between this one and the ethanolate as the glycosyl acceptor model. In general, the presence of direct interactions between the atoms involved in the penta-coordinated TS increases the activation energies of the processes.

  14. Buffering dissociation/formation reaction of biogenic calcium carbonate.

    Science.gov (United States)

    Ichikawa, Kazuhiko

    2007-01-01

    The oscillating stability of coral reef seawater pH has been maintained at around physiological pH values over the past 300 years (Pelejero et al., 2005). The stability mechanism of its pH has been interpreted in terms of the buffering dissolution/formation reaction of CaCO(3) as well as the proton consumption/generation reaction in CaCO(3)-saturated water. Here the pH-dependent solubility product [HCO(3)(-)][Ca(2+)] has been derived on the basis of the actual pH-dependent reactions for the atmospheric CO(2)/CO(2 (aq.))/HCO(3)(-)/CO(3)(2-)/Ca(2+)/CaCO(3) system. Overbasic pH peaks appeared between pH approximately 8 and approximately 9.5 during sodium hydroxide titration, as a result of simultaneous CaCO(3) formation and proton generation. The spontaneous and prompt water pH recovery from the acidic to the physiological range has been confirmed by the observation of acid/base time evolution, because of simultaneous CaCO(3) dissolution and proton consumption. The dissolution/formation of CaCO(3) in water at pH 7.5-9 does not take place without a proton consumption/generation reaction, or a buffering chemical reaction of HCO(3)(-)+Ca(2+)right arrow over left arrowCaCO(3)+H(+). SEM images of the CaCO(3) fragments showed that the acid water ate away at the CaCO(3) formed at physiological pH values. Natural coral reefs can thus recover the physiological pH levels of seawater from the acidic range through partial dissolution of their own skeletons.

  15. XPS study on the surface reaction of uranium metal with carbon monoxide at 200 degree C

    International Nuclear Information System (INIS)

    Wang Xiaoling; Fu Yibei; Xie Renshou; Huang Ruiliang

    1996-12-01

    The surface reaction of uranium metal with carbon monoxide at 200 degree C has been studied by X-ray photoelectron spectroscopy (XPS). The carbon monoxide adsorption on the surface oxide layer resulted in U4f peak shifting to the lower binding energy and the content of oxygen in the oxide is decreased. O/U radio decreases with increasing the exposure of carbon monoxide to the surface layer. The investigation indicated the surface layer of uranium metal was further reduced in the atmosphere of carbon monoxide at high temperature. (3 refs., 5 figs.)

  16. Hybrid direct carbon fuel cells and their reaction mechanisms - a review

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Kammer Hansen, Kent

    2014-01-01

    with carbon capture and storage (CCS) due to the high purity of CO2 emitted in the exhaust gas. Direct carbon (or coal) fuel cells (DCFCs) are directly fed with solid carbon to the anode chamber. The fuel cell converts the carbon at the anode and the oxygen at the cathode into electricity, heat and reaction......As coal is expected to continue to dominate power generation demands worldwide, it is advisable to pursue the development of more efficient coal power generation technologies. Fuel cells show a much higher fuel utilization efficiency, emit fewer pollutants (NOx, SOx), and are more easily combined...

  17. Research of Hydrogen Preparation with Catalytic Steam-Carbon Reaction Driven by Photo-Thermochemistry Process

    Directory of Open Access Journals (Sweden)

    Xiaoqing Zhang

    2013-01-01

    Full Text Available An experiment of hydrogen preparation from steam-carbon reaction catalyzed by K2CO3 was carried out at 700°C, which was driven by the solar reaction system simulated with Xenon lamp. It can be found that the rate of reaction with catalyst is 10 times more than that without catalyst. However, for the catalytic reaction, there is no obvious change for the rate of hydrogen generation with catalyst content range from 10% to 20%. Besides, the conversion efficiency of solar energy to chemical energy is more than 13.1% over that by photovoltaic-electrolysis route. An analysis to the mechanism of catalytic steam-carbon reaction with K2CO3 is given, and an explanation to the nonbalanced [H2]/[CO + 2CO2] is presented, which is a phenomenon usually observed in experiment.

  18. Initial reaction between CaO and SO2 under carbonating and non-carbonating conditions

    DEFF Research Database (Denmark)

    Rasmussen, Martin Hagsted; Wedel, Stig; Pedersen, Kim H.

    2015-01-01

    The initial kinetics of the CaO/SO2 reaction have been investigated for reaction times shorter than 1s and in the temperature interval between 450 and 600°C under both carbonating and non-carbonating conditions (0-20 vol% CO2) to clarify how recirculating CaO influences the emission of SO2 from...... showed that the CaO conversion with respect to SO2 declined when the CO2 concentration was increased. Under all conditions, larger specific surface areas of CaO gave higher reaction rates with SO2. Higher temperatures had a positive effect on the reaction between SO2 and CaO under non......-carbonating conditions, but no or even a negative effect under carbonating conditions. The results led to the conclusion that SO2 released from raw meal in the upper stages of the preheater does not to any significant extent react with CaO recirculating in the preheater tower....

  19. Reactions between sodium and various carbon bearing compounds

    Energy Technology Data Exchange (ETDEWEB)

    Raine, A C; Thorley, A W [UKAEA, Risley, Warrington, Cheshire (United Kingdom)

    1980-05-01

    The presence of carbon bearing materials in liquid sodium is undesirable because of their ability to carburise stainless steel components. It has been demonstrated for example that carbon taken up by stainless steels can affect their mechanical properties and that thinner sectioned material such as fuel cladding and the tubing of intermediate heat exchanger may be more sensitive to such effects. Generally speaking, there are a number of potential carbon sources in reactor systems. Some of the sources such as the graphite in neutron shield rods, boron carbide in control rods and carbide fuels are part of the reactor designs while others such as oil in mechanical pumps arid 'coupling-fluids' used to inspect plant components are associated with the respective operation arid inspection of the plant. In this paper it is intended to discuss in general terms the way these various compounds behave in liquid sodium and to assess what effect their presence will have on the materials of construction in fast reactor systems. The paper also reviews the chemistry of the environment in relation to the types of carburizing species which may exist in sodium systems.

  20. Elastic scattering, inelastic scattering, and transfer reactions induced by 12C bombardment of 12C

    International Nuclear Information System (INIS)

    Stokstad, R.G.; Wieland, R.M.; Fulmer, C.B.; Hensley, D.C.; Raman, S.; Snell, A.H.; Stelson, P.H.

    1977-06-01

    Graphs and tables of differential cross sections are presented for the elastic scattering of 12 C by 12 C, the single excitation (Q = -4.43 MeV) and the mutual excitation (Q = -8.86 MeV) for 14 bombarding energies in the range 70.7 less than or equal to E/sub lab/ less than or equal to 126.7 MeV. Differential cross sections for one- and two-nucleon transfer are presented for E/sub lab/ = 93.8 MeV

  1. Kinetic Modeling of the Reaction Rate for Quartz and Carbon Pellet

    Science.gov (United States)

    Li, Fei; Tangstad, Merete

    2018-04-01

    Kinetic modeling of quartz and carbon pellet at temperatures of 1898 K, 1923 K, and 1948 K (1625 °C, 1650 °C, and 1675 °C) was investigated in this study. The carbon materials used were charcoal, coke, coal, and preheated coal. The overall SiC producing reaction can be described by the reaction SiO2 + 3C = SiC + 2CO. In the SiC-producing step, the reaction rate of quartz and carbon pellet can be expressed as {d{ pct}}/dt = ( {1 - 0.40 × X_{fix - C}^{ - 0.86} × FC × {pct}} ) × A × \\exp ( { - E/{{RT}}} ) The carbon factor F C was used to describe the influence of different carbon materials that effect the gas-solid interface reaction. For charcoal, coke, coal, and preheated coal, the F C values were 0.83, 0.80, 0.94, and 0.83, respectively. The pre-exponential factor A values for the preceding four carbon materials were 1.06 × 1016 min-1, 4.21 × 1015 min-1, 3.85 × 109 min-1, and 1.00 × 1025 min-1, respectively. The activation energies E for the SiC-producing step were 570, 563, 336, and 913 kJ/mole for charcoal, coke, coal, and preheated coal pellets, respectively.

  2. Spectroscopic information from (3He, 7Be) reaction on 12C and 24Mg

    International Nuclear Information System (INIS)

    Rahman, Md.A.; Sen Gupta, H.M.

    1986-01-01

    The reaction ( 3 He, 7 Be) on 12 C and 24 Mg has been analysed using four discrete potential families for 7 Be channel and one discrete potential family for 3 He channel to extract alpha spectroscopic factors. It is shown that the relative spectroscopic factors are reliable if they are calculated staying within one potential family (S( 24 Mg/ 12 C) approx. 0.12). But, changing the potential family between 12 C and 24 Mg, one obtains the extreme cases, such as S( 24 Mg/ 12 C) = 0.025 and 0.51, i.e. 1:20

  3. Reactions of carbon radicals generated by 1,5-transposition of reactive centers

    Directory of Open Access Journals (Sweden)

    ZIVORAD CEKOVIC

    2005-03-01

    Full Text Available Radical intermediates can undergo specific reactions, such as intramolecular rearrangements, i.e., the transpositions of radical centers, which are not known in classical ionic organic reactions. 1,5-Transposition of a radical center to a non-activated carbon atom are of great synthetic importance. It can be successfully applied for the introduction of different functional groups (oxygen, nitrogen, sulfur, halogens onto a carbon atom remote from the present functional group. In addition to functionalization of a remote non-activated carbon atom, the formation of new C-C bonds on the d-carbon atom have also been achieved. 1,5-Transposition of the radical centers takes place from alkoxyl, aminyl and carbon radicals to a remote carbon atom. Relocation of the radical centers preferentially involves 1,5-transfer of a hydrogen atom, although migrations of some other groups are known. The reactions of the carbon radical generated by 1,5-relocation of the radical center are presented and their synthetic applications are reviewed.

  4. Crossed-beam reaction of carbon atoms with hydrocarbon molecules. IV. Chemical dynamics of methylpropargyl radical formation, C4H5, from reaction of C(3Pj) with propylene, C3H6 (X1A)

    International Nuclear Information System (INIS)

    Kaiser, R.I.; Stranges, D.; Bevsek, H.M.; Lee, Y.T.; Suits, A.G.

    1997-01-01

    The reaction between ground state carbon atoms and propylene, C 3 H 6 , was studied at average collision energies of 23.3 and 45.0 kJmol -1 using the crossed molecular beam technique. Product angular distributions and time-of-flight spectra of C 4 H 5 at m/e=53 were recorded. Forward-convolution fitting of the data yields a maximum energy release as well as angular distributions consistent with the formation of methylpropargyl radicals. Reaction dynamics inferred from the experimental results suggest that the reaction proceeds on the lowest 3 A surface via an initial addition of the carbon atom to the π-orbital to form a triplet methylcyclopropylidene collision complex followed by ring opening to triplet 1,2-butadiene. Within 0.3 endash 0.6 ps, 1,2-butadiene decomposes through carbon endash hydrogen bond rupture to atomic hydrogen and methylpropargyl radicals. The explicit identification of C 4 H 5 under single collision conditions represents a further example of a carbon endash hydrogen exchange in reactions of ground state carbon with unsaturated hydrocarbons. This versatile machine represents an alternative pathway to build up unsaturated hydrocarbon chains in combustion processes, chemical vapor deposition, and in the interstellar medium. copyright 1997 American Institute of Physics

  5. The reaction 12C + 12C at bombarding energies from 5 to 10 MeV per nucleon

    International Nuclear Information System (INIS)

    Morsad, A.

    1986-01-01

    The reaction 12 C + 12 C has been studied for energies ranging from E LAB = 60 to 120 MeV. The excitation functions and angular distributions were obtained for the elastic (0 + , 0 + ) and inelastic (2 + , 0 + ), (2 + , 2 + ) channels as well as for the transfer channels of one and two nucleons. For the transfer reactions, the feeding of the final bound states was very selective. Narrow correlated structures were found in the transfer and especially in the elastic and inelastic channels. In this energy range, there appears to be a transition from surface transparency to interference phenomena. The optical model in its simplest form is unable to describe the elastic scattering at large angles. This has been interpreted as a consequence of the coupling between the elastic and inelastic channels which is particularly strong of these energies. 80 refs [fr

  6. Aligned carbon nanotube with electro-catalytic activity for oxygen reduction reaction

    Science.gov (United States)

    Liu, Di-Jia; Yang, Junbing; Wang, Xiaoping

    2010-08-03

    A catalyst for an electro-chemical oxygen reduction reaction (ORR) of a bundle of longitudinally aligned carbon nanotubes having a catalytically active transition metal incorporated longitudinally in said nanotubes. A method of making an electro-chemical catalyst for an oxygen reduction reaction (ORR) having a bundle of longitudinally aligned carbon nanotubes with a catalytically active transition metal incorporated throughout the nanotubes, where a substrate is in a first reaction zone, and a combination selected from one or more of a hydrocarbon and an organometallic compound containing an catalytically active transition metal and a nitrogen containing compound and an inert gas and a reducing gas is introduced into the first reaction zone which is maintained at a first reaction temperature for a time sufficient to vaporize material therein. The vaporized material is then introduced to a second reaction zone maintained at a second reaction temperature for a time sufficient to grow longitudinally aligned carbon nanotubes over the substrate with a catalytically active transition metal incorporated throughout the nanotubes.

  7. Analytical applications of the 12C(d,p) reaction. Treatment of experimental spectra

    International Nuclear Information System (INIS)

    Engerran, J.-A.

    1975-01-01

    The nuclear (d,p) reaction induced on carbon and oxygen at medium energies (1 to 4MeV) has been used for the determination of very small quantities (less than a monolayer) as well as of the in-depth distribution. With respect to the first feature of this reaction, chemisorption study has been undertaken for the mixture CO/O 2 at the surface of a polycristalline sample of platinum. An adapted irradiation detection set-up is described. Obtaining the in-depth distribution leads to the more general case of treatment of experimental spectra. Owing to the results given by the classical methods of deconvolution or convolution, a joint procedure was chosen for our application. A trial function is determined by a convolutionprocess, to be used as initial function in an iterative method. Convergence is then easily achieved avoiding Gibbs phenomena. As a main application, carbon profile determination is obtained for a boron matrix [fr

  8. Calculation of astrophysical S-factor and reaction rate in 12C(p, γ)13N reaction

    Science.gov (United States)

    Moghadasi, A.; Sadeghi, H.; Pourimani, R.

    2018-02-01

    The 12C(p, γ)13N reaction is the first process in the CNO cycle. Also it is a source of low-energy solar neutrinos in various neutrino experiments. Therefore, it is of high interest to gain data of the astrophysical S-factor in low energies. By applying Faddeev's method, we calculated wave functions for the bound state of 13N. Then the cross sections for resonance and non-resonance were calculated through using Breit-Wigner and direct capture cross section formulae, respectively. After that, we calculated the total S-factor and compared it with previous experimental data, revealing a good agreement altogether. Then, we extrapolated the S-factor in zero energy and the result was 1.32 ± 0.19 (keV.b). In the end, we calculated reaction rate and compared it with NACRE data.

  9. Enhanced interfacial properties of carbon fiber composites via aryl diazonium reaction “on water”

    Science.gov (United States)

    Wang, Yuwei; Meng, Linghui; Fan, Liquan; Ma, Lichun; Qi, Meiwei; Yu, Jiali; Huang, Yudong

    2014-10-01

    Polyacrylonitrile-based carbon fibers were functionalized with phenyl amine group via aryl diazonium reaction "on water" to improve their interfacial bonding with resin matrix. Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy were employed to characterize ordered degree, functional groups, chemical states and morphology of carbon fiber surface, respectively. The results showed that phenyl amine groups were grafted on the fiber surface successfully. Mechanical property test results indicated that the aryl diazonium reaction in this paper could improve the interfacial shear strength by 73%, while the tensile strength was down very slightly. Hence aryl diazonium reaction "on water" could be a facile green platform to functionalize carbon fibers for many interesting applications.

  10. The opacities of 12C-12C reaction and effect of deformed target nucleus on abrasion and absorption cross sections

    International Nuclear Information System (INIS)

    Ramadan, S.; Metawei, Z.

    1995-01-01

    The values of the opacities for 12 C- 12 C reaction are calculated at different incident ion kinetic energy. The exact multiple scattering series for the scattering of two heavy ions which was derived by wilson is used to calculate the abrasion and absorption cross sections of 16 O- 9 Be and 16 O- 16 O collisions, considering a harmonic oscillator matter density for both target and projectiles as spherical nuclei. The effect of including the pauli correlation is considered. The case of deformed target is also investigated. Our results are compared with other calculations as well as with the experimental results

  11. Quasimolecular states in a reaction with carbon isotopes

    Czech Academy of Sciences Publication Activity Database

    Torilov, S. Yu.; Maltsev, N. A.; Goldberg, V. Z.; Gridnev, K. A.; Zherebchevsky, V. I.; Lönnroth, T.; Novatskii, B. G.; Slotte, J. M. K.; Sobolev, Yuri, G.; Trzaska, W. H.; Tyurin, G. P.; Khlebnikov, S. V.

    2015-01-01

    Roč. 102, č. 2 (2015), s. 69-72 ISSN 0021-3640 R&D Projects: GA MŠk LG14004 Institutional support: RVO:61389005 Keywords : rich Be isotope * C isotope * C-14+C-12 Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.172, year: 2015

  12. Reactions of carbon acids and 1,3-dipoles in the presence of ionic liquids

    International Nuclear Information System (INIS)

    Zlotin, Sergei G; Makhova, Nina N

    2010-01-01

    The review is devoted to the use of ionic liquids as solvents, immobilized organocatalysts and reagents in reactions involving carbon acids and 1,3-dipoles, which are widely used to prepare practically valuable organic compounds of various classes. The characteristic features of processes in the presence of ionic liquids, the effects of the structure of cations and anions on the regio-, stereo- and enantioselectivities of reactions and methods of recovery of ionic liquids are considered.

  13. Chemical Reaction Equilibrium in Nanoporous Materials: NO Dimerization Reaction in Carbon Slit Nanopores

    Czech Academy of Sciences Publication Activity Database

    Lísal, Martin; Brennan, J.K.; Smith, W.R.

    2006-01-01

    Roč. 124, č. 6 (2006), s. 64712.1-64712.14 ISSN 0021-9606 R&D Projects: GA ČR(CZ) GA203/05/0725; GA AV ČR(CZ) 1ET400720507; GA AV ČR(CZ) 1ET400720409 Institutional research plan: CEZ:AV0Z40720504 Keywords : nanopore * NO dimerization * reaction Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.166, year: 2006

  14. Comparison of two analysis methods for nuclear reaction measurements of {sup 12}C +{sup 12}C interactions at 95 MeV/u for hadron therapy

    Energy Technology Data Exchange (ETDEWEB)

    Dudouet, J. [LPC Caen, ENSICAEN, Université de Caen, CNRS/IN2P3, Caen (France); Juliani, D. [Institut Pluridisciplinaire Hubert Curien Strasbourg (France); Labalme, M., E-mail: labalme@lpccaen.in2p3.fr [LPC Caen, ENSICAEN, Université de Caen, CNRS/IN2P3, Caen (France); Angélique, J.C. [LPC Caen, ENSICAEN, Université de Caen, CNRS/IN2P3, Caen (France); Braunn, B. [CEA, Centre de Saclay, IRFU/SPhN, F-91191, Gif-sur-Yvette (France); Colin, J.; Cussol, D. [LPC Caen, ENSICAEN, Université de Caen, CNRS/IN2P3, Caen (France); Finck, Ch. [Institut Pluridisciplinaire Hubert Curien Strasbourg (France); Fontbonne, J.M.; Guérin, H. [LPC Caen, ENSICAEN, Université de Caen, CNRS/IN2P3, Caen (France); Henriquet, P.; Krimmer, J. [IPNL, Université de Lyon, F-69003 Lyon (France); Université Lyon 1 and CNRS/IN2P3, UMR 5822 F-69622 Villeurbanne (France); Rousseau, M. [Institut Pluridisciplinaire Hubert Curien Strasbourg (France); Saint-Laurent, M.G. [Grand Accélérateur National d' Ions Lourds (GANIL), CEA/DSM-CNRS/IN2P3 BP5027,F-14076 Caen cedex 5 (France)

    2013-07-01

    During therapeutic treatment with heavier ions like carbon, the beam undergoes nuclear fragmentation and secondary light charged particles, in particular protons and alpha particles, are produced. To estimate the dose deposited into the tumors and the surrounding healthy tissues, the accuracy must be higher than ±3% and±1 mm. Therefore, measurements are performed to determine the double differential cross-section for different reactions. In this paper, the analysis of data from {sup 12}C +{sup 12}C reactions at 95 MeV/u are presented. The emitted particles are detected with ΔE{sub thin}−ΔE{sub thick}−E telescopes made of a stack of two silicon detectors and a CsI crystal. Two different methods are used to identify the particles. One is based on graphical cuts onto the ΔE−E maps, the second is based on the so-called KaliVeda method using a functional description of ΔE versus E. The results of the two methods will be presented in this paper as well as the comparison between both.

  15. Investigation of the 9Be(a,n)12C reaction. Pt. 2

    International Nuclear Information System (INIS)

    Schmidt, D.; Boettger, R.; Klein, H.; Nolte, R.

    1992-04-01

    Differential cross sections of the 9 Be(α,n) 12 C reaction have been measured at 19 alpha energies between 7 MeV and 16 MeV. Besides the differential cross sections from the 9 Be(α,n) 12 C(g.s.) reaction, also those of the 9 Be(α,n) 12 C(E ex ) reactions were derived for excitation energies E ex = 4.439, 7.654, 9.641, 10.84, 11.83 and 12.71 MeV. Possible sources of uncertainties have been extensively investigated and the corresponding results have been published in part 1. All partial and integrated cross sections from the 9 Be(α,n) 12 C(g.s.) reaction were determined with uncertainties of less than 5%. The angular distributions were fitted to Legendre polynomial expansions by the least-squares method. A comparison of the measured cross sections with data from other authors and with an evaluation shows considerable deviations in some cases. Tests were also carried out to ascertain how well an interpolation of the Legendre coefficients reproduces the magnitude and shape of the experimentally determined angular distributions. All angular distributions are presented in figures, together with their Legendre polynomial expansions and data from the literature if available. The a l coefficients of the Legendre polynomial expansions are given in the Appendix. (orig.) [de

  16. Stereochemistry of 1,2-elimination and proton-transfer reactions: toward a unified understanding.

    Science.gov (United States)

    Mohrig, Jerry R

    2013-07-16

    Many mechanistic and stereochemical studies have focused on the breaking of the C-H bond through base-catalyzed elimination reactions. When we began our research, however, chemists knew almost nothing about the stereospecificity of addition-elimination reactions involving conjugated acyclic carbonyl compounds, even though the carbonyl group is a pivotal functional group in organic chemistry. Over the last 25 years, we have studied the addition-elimination reactions of β-substituted acyclic esters, thioesters, and ketones in order to reach a comprehensive understanding of how electronic effects influence their stereochemistry. This Account brings together our understanding of the stereochemistry of 1,2-elimination and proton-transfer reactions, describing how each study has built upon previous work and contributed to our understanding of this field. When we began, chemists thought that anti stereospecificity in base-catalyzed 1,2-elimination reactions occurred via concerted E2 mechanisms, which provide a smooth path for anti elimination. Unexpectedly, we discovered that some E1cBirrev reactions produce the same anti stereospecificity as E2 reactions even though they proceed through diffusionally equilibrated, "free" enolate-anion intermediates. This result calls into question the conventional wisdom that anti stereochemistry must result from a concerted mechanism. While carrying out our research, we developed insights ranging from the role of historical contingency in the evolution of hydratase-dehydratase enzymes to the influence of buffers on the stereochemistry of H/D exchange in D2O. Negative hyperconjugation is the most important concept for understanding our results. This idea provides a unifying view for the largely anti stereochemistry in E1cBirrev elimination reactions and a basis for understanding the stereoelectronic influence of electron-withdrawing β-substituents on proton-transfer reactions.

  17. Kinetics of reactions of oxidation of carbon by carbon dioxide and water steam at high temperatures and low pressures

    International Nuclear Information System (INIS)

    Boulangier, Francois

    1956-01-01

    The first objective of this research thesis was to obtain new and reliable experimental results about the reaction kinetics of the oxidation of carbon by carbon dioxide and water steam, and to avoid some disturbing phenomena, for example and more particularly the appearance of electric discharges beyond 1900 K initiated by the filament thermoelectric emission. The author tried to identify the mechanism of the accelerating effect. It appears that previous experiments had been performed only in these disturbed conditions. At the lowest temperatures, the author highlighted the existence of a surface contamination by the desorption products from the apparatus [fr

  18. Study of the alpha+12C →16O capture via 12C(16O,12C)16O transfer reaction

    International Nuclear Information System (INIS)

    Morais, M.C.; Lichtenthaeler, R.; Arazi, A.; Hojman, D.; Cardona, M.A.; Fimiani, L.; Carnelli, P.F.; Marti, G.V.; Pacheco, A.J.; Heimann, D. Martinez; Negri, A.E.; Capurro, O.A.; Niello, J.O. Fernandez; Montero, P.

    2009-01-01

    Full text: The 12 C(α γ) 16 O reaction is one of the most important in nuclear astrophysics. The rate of this reaction influences the subsequent nucleosynthesis of heavier elements in massive stars and consequently determines the stellar evolution. The 12 C(α γ) 16 O reaction cross section is extremely small at stellar temperature, this is mainly due to the Gamow energy (∼ 300KeV at T= 2x10 8 K) be much lower than the Coulomb barrier, E C.B. : = 3:142MeV. The α+ 12 C → 16 O at low energies is dominated by subthreshold states (1 - , 7:12MeV) and (2 + , 6:92MeV) of the 16 O, thus spectroscopic factors measurements of these states are very important. We propose to use the α-transfer reaction 12 C( 16 O, 12 C) 16 O * at very forward angles to obtain those spectroscopic factors. In this way, measurements of elastic and inelastic angular distributions for the 12 C+ 16 O system were performed at the TANDAR Laboratory in Buenos Aires, using an 16 O beam of E lab = 46.3MeV. These angular distributions were obtained using 8 adjacent surface barrier detectors and the measurements were performed from 5 deg to 48.5 deg with steps of 1 deg. The scattering chamber has an angular precision better than 0.1 deg. The transfer angular distributions are being analysed by DWBA using the computer code FRESCO in order to obtain the two spectroscopic factors. (author)

  19. Ambient Mechanochemical Solid-State Reactions of Carbon Nanotubes and Their Reactions via Covalent Coordinate Bond in Solution

    Science.gov (United States)

    Kabbani, Mohamad A.

    In its first part, this thesis deals with ambient mechanochemical solid-state reactions of differently functionalized multiple walled carbon nanotubes (MWCNTs) while in its second part it investigates the cross-linking reactions of CNTs in solution via covalent coordinate bonds with transitions metals and carboxylate groups decorating their surfaces. In the first part a series of mechanochemical reactions involving different reactive functionalities on the CNTs such as COOH/OH, COOH/NH2 and COCl/OH were performed. The solid-state unzipping of CNTs leading to graphene formation was confirmed using spectroscopic, thermal and electron microscopy techniques. The non-grapheme products were established using in-situ quadruple mass spectroscopy. The experimental results were confirmed by theoretical simulation calculations using the 'hot spots' protocol. The kinetics of the reaction between MWCNT-COOH and MWCNT-OH was monitored using variable temperature Raman spectroscopy. The low activation energy was discussed in terms of hydrogen bond mediated proton transfer mechanism. The second part involves the reaction of MWCNTII COOH with Zn (II) and Cu (II) to form CNT metal-organic frame (MOFs) products that were tested for their effective use as counter-electrodes in dyes sensitized solar cells (DSSC). The thesis concludes by the study of the room temperature reaction between the functionalized graphenes, GOH and G'-COOH followed by the application of compressive loads. The 3D solid graphene pellet product ( 0.6gm/cc) is conductive and reflective with a 35MPa ultimate strength as compared to 10MPa strength of graphite electrode ( 2.2gm/cc).

  20. Transition metal-catalyzed carboxylation reactions with carbon dioxide.

    Science.gov (United States)

    Martin, Ruben; Tortajada, Andreu; Juliá-Hernández, Francisco; Borjesson, Marino; Moragas, Toni

    2018-05-03

    Driven by the inherent synthetic potential of CO2 as an abundant, inexpensive and renewable C1 chemical feedstock, the recent years have witnessed renewed interest in devising catalytic CO2 fixations into organic matter. Although the formation of C-C bonds via catalytic CO2 fixation remained rather limited for a long period of time, a close look into the recent literature data indicates that catalytic carboxylation reactions have entered a new era of exponential growth, evolving into a mature discipline that allows for streamlining the synthesis of carboxylic acids, building blocks of utmost relevance in industrial endeavours. These strategies have generally proven broadly applicability and convenient to perform. However, substantial challenges still need to be addressed reinforcing the need to cover metal-catalyzed carboxylation arena in a conceptual and concise manner, delineating the underlying new principles that are slowly emerging in this vibrant area of expertise. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Synthesis and Some Reactions of 3-Chloro-2-(cyanomethylene-1,2-dihydroquinoxalines

    Directory of Open Access Journals (Sweden)

    Wolfgang Pfleiderer

    2004-03-01

    Full Text Available 2,3-Dichloroquinoxaline and some of its derivatives have been reacted with malononitrile and ethyl cyanoacetate to yield a variety of 3-chloro-2-(cyanomethylene- 1,2-dihydroquinoxaline derivatives. The reaction of 3-chloro-2-(dicyanomethylene-1,2- dihydroquinoxaline (2e with pyridine and its methyl derivatives led to the zwitterionic structures 6a-6c. The structures of the newly synthesized compounds were assigned by spectroscopic data and elemental analyses.

  2. Effect of reaction temperature on structure and fluorescence properties of nitrogen-doped carbon dots

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yi [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Department of Chemistry and Chemical Engineering, Lyuliang University, Lyuliang 033001 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Wang, Yaling [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Feng, Xiaoting [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Zhang, Feng [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Yang, Yongzhen, E-mail: yyztyut@126.com [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Liu, Xuguang, E-mail: liuxuguang@tyut.edu.cn [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China)

    2016-11-30

    Highlights: • Nitrogen-doped carbon dots (NCDs) from ammonia solution and citric acid were synthesized at different temperatures. • Quantum yield (QY) of NCDs depends largely on the amount of fluorescent polymer chains (FPC), more FPC gives higher QY. • The law of QY of NCDs first increase and then decrease with the reaction temperature increased is found and explained. • Nitrogen doping plays significant role in getting increased UV–vis absorption and QY. - Abstract: To investigate the effect of reaction temperature and nitrogen doping on the structure and fluorescence properties of carbon dots (CDs), six kinds of nitrogen-doped CDs (NCDs) were synthesized at reaction temperatures of 120, 140, 160, 180, 200 and 220 °C, separately, by using citric acid as carbon source and ammonia solution as nitrogen source. Nitrogen-free CDs (N-free CDs-180) was also prepared at 180 °C by using citric acid as the only carbon source for comparison. Results show that reaction temperature has obvious effect on carbonization degree, quantum yield (QY), ultraviolet-visible (UV–vis) absorption and photoluminescence (PL) spectra but less effect on functional groups, nitrogen doping degree and fluorescence lifetime of NCDs. Compared with N-free CDs-180, NCDs-180 possesses enchanced QY and longer fluorescence lifetime. Doping nitrogen has obvious effect on UV–vis absorption and PL spectra but less effect on particles sizes and carbonization degree. The formation mechanism of NCDs is explored: QY of NCDs depends largely on the number of fluorescent polymer chains (FPC), the competition between FPC formation on the surface of NCDs and carbon core growth leads to the change in number of FPC, and consequently to the NCDs with highest QY at appropriate hydrothermal temperature.

  3. Kinetics of Several Oxygen-Containing Carbon-Centered Free Radical Reactions with Nitric Oxide.

    Science.gov (United States)

    Rissanen, Matti P; Ihlenborg, Marvin; Pekkanen, Timo T; Timonen, Raimo S

    2015-07-16

    Kinetics of four carbon-centered, oxygen-containing free radical reactions with nitric oxide (NO) were investigated as a function of temperature at a few Torr pressure of helium, employing flow tube reactors coupled to a laser-photolysis/resonance-gas-discharge-lamp photoionization mass spectrometer (LP-RPIMS). Rate coefficients were directly determined from radical (R) decay signals under pseudo-first-order conditions ([R]0 ≪ [NO]). The obtained rate coefficients showed negative temperature dependences, typical for a radical-radical association process, and can be represented by the following parametrizations (all in units of cm(3) molecule(-1) s(-1)): k(CH2OH + NO) = (4.76 × 10(-21)) × (T/300 K)(15.92) × exp[50700/(RT)] (T = 266-363 K, p = 0.79-3.44 Torr); k(CH3CHOH + NO) = (1.27 × 10(-16)) × (T/300 K)(6.81) × exp[28700/(RT)] (T = 241-363 K, p = 0.52-3.43 Torr); k(CH3OCH2 + NO) = (3.58 ± 0.12) × 10(-12) × (T/300 K)(-3.17±0.14) (T = 221-363 K, p = 0.50-0.80 Torr); k(T)3 = 9.62 × 10(-11) × (T/300 K)(-5.99) × exp[-7100/(RT)] (T = 221-473 K, p = 1.41-2.95 Torr), with the uncertainties given as standard errors of the fits and the overall uncertainties estimated as ±20%. The rate of CH3OCH2 + NO reaction was measured in two density ranges due to its observed considerable pressure dependence, which was not found in the studied hydroxyalkyl reactions. In addition, the CH3CO + NO rate coefficient was determined at two temperatures resulting in k298K(CH3CO + NO) = (5.6 ± 2.8) × 10(-13) cm(3) molecule(-1) s(-1). No products were found during these experiments, reasons for which are briefly discussed.

  4. Biogeochemical stability and reactions of iron-organic carbon complexes

    Science.gov (United States)

    Yang, Y.; Adhikari, D.; Zhao, Q.; Dunham-Cheatham, S.; Das, K.; Mejia, J.; Huang, R.; Wang, X.; Poulson, S.; Tang, Y.; Obrist, D.; Roden, E. E.

    2017-12-01

    Our core hypothesis is that the degradation rate of soil organic carbon (OC) is governed by the amount of iron (Fe)-bound OC, and the ability of microbial communities to utilize OC as an energy source and electron shuttle for Fe reduction that in turn stimulates reductive release of Fe-bound labile dissolved OC. This hypothesis is being systematically evaluated using model Fe-OC complexes, natural soils, and microcosm system. We found that hematite-bound aliphatic C was more resistant to reduction release, although hematite preferred to sorb more aromatic C. Resistance to reductive release represents a new mechanism that aliphatic soil OC was stabilized by association with Fe oxide. In other studies, pyrogenic OC was found to facilitate the reduction of hematite, by enhancing extracellular electron transport and sorbing Fe(II). For ferrihydrite-OC co-precipitates, the reduction of Fe and release of OC was closely governed by the C/Fe ratio in the system. Based on the XPS, XANES and XAFS analysis, the transformation of Fe speciation was heterogeneous, depending on the conformation and composition of Fe-OC complexes. For natural soils, we investigated the quantity, characteristics, and reactivity of Fe-bound OC in soils collected from 14 forests in the United States. Fe-bound OC contributed up to 57.8% of total OC in the forest soils. Under the anaerobic conditions, the reduction of Fe was positively correlated to the electron accepting capacity of OC. Our findings highlight the closely coupled dynamics of Fe and OC, with broad implications on the turnover of OC and biogeochemical cycles of Fe.

  5. Synthesis of E-Diiodoalkenes: 1,2-diaminobenzene Activated Reaction of Alkvnes With iodine

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Article history:ReceivedReceived in revised formAcceptedAvailable online 1,2-diaminobenzene was found to active the reaction of iodine with terminal alkynes and E-diiodoalkenes were obtained in good to excellent yields.2009 Elsevier Ltd. All rights reserved.

  6. Fragment production in 12-GeV proton-induced reactions

    International Nuclear Information System (INIS)

    Hirata, Yuichi; Ohnishi, Akira; Ohtsuka, Naohiko; Nara, Yasushi; Niida, Koji; Chiba, Satoshi; Takada, Hiroshi

    2000-01-01

    We study mass and angular distribution of Intermediate Mass Fragment (IMF) produced from p(12 GeV)+ 197 Au reaction by using JAM cascade model combined with percolation model. Although the mass distribution of IMF is well reproduced, the experimentally observed sideward peak of IMF angular distribution is not explained within present JAM + percolation model. (author)

  7. Probing the Statistical Decay and α-clustering effects in 12C + 12C and 14N + 10B reactions

    Directory of Open Access Journals (Sweden)

    Morelli L.

    2014-03-01

    Full Text Available An experimental campaign has been undertaken at Laboratori Nazionali di Legnaro (LNL INFN, Italy, in order to progress in our understanding of the statistical properties of light nuclei at excitation energies above particle emission threshold, by measuring exclusive data from fusion-evaporation reactions. On the experimental side, a first reaction: 12C+12C at 95 MeV beam energy has been measured, using the GARFIELD + Ring Counter (RCo apparatuses. Fusion-evaporation events have been exclusively selected out of the entire data set. The comparison to a dedicated Hauser-Feshbach calculation allows us to give constraints on the nuclear level density at high excitation energy for light systems ranging from C up to Mg. Out-of-equilibrium aα emission has been evidenced and attributed both to an entrance channel effect (favoured by the cluster nature of reaction partners, and, in more dissipative events, to the persistence of cluster correlations well above the 24Mg threshold for 6 α’s decay. In order to study the same 24Mg compound nucleus at similar excitation energy with respect to this first reaction a new measurement, 14N + 10B at 5.7 A.MeV, was performed at LNL laboratories with the same experimental setup. The comparison between the two systems would allow us to further constrain the level density of light nuclei in the mass-excitation energy range of interest. In this perspective, deviations from a statistical behaviour can be used as a tool to get information on nuclear clustering, both in the ground-state for projectile and target and in the hot source formed in the collision.

  8. Mineral carbonation: energy costs of pretreatment options and insights gained from flow loop reaction studies

    Energy Technology Data Exchange (ETDEWEB)

    Penner, Larry R.; O' Connor, William K.; Dahlin, David C.; Gerdemann, Stephen J.; Rush, Gilbert E.

    2004-01-01

    Sequestration of carbon as a stable mineral carbonate has been proposed to mitigate environmental concerns that carbon dioxide may with time escape from its sequestered matrix using alternative sequestration technologies. A method has been developed to prepare stable carbonate products by reacting CO2 with magnesium silicate minerals in aqueous bicarbonate/chloride media at high temperature and pressure. Because this approach is inherently expensive due to slow reaction rates and high capital costs, studies were conducted to improve the reaction rates through mineral pretreatment steps and to cut expenses through improved reactor technology. An overview is given for the estimated cost of the process including sensitivity to grinding and heating as pretreatment options for several mineral feedstocks. The energy costs are evaluated for each pretreatment in terms of net carbon avoided. New studies with a high-temperature, high-pressure flow-loop reactor have yielded information on overcoming kinetic barriers experienced with processing in stirred autoclave reactors. Repeated tests with the flow-loop reactor have yielded insights on wear and failure of system components, on challenges to maintain and measure flow, and for better understanding of the reaction mechanism.

  9. Mineral carbonation: energy costs of pretreatment options and insights gained from flow loop reaction studies

    International Nuclear Information System (INIS)

    Penner, Larry R.; O'Connor, William K.; Dahlin, David C.; Gerdemann, Stephen J.; Rush, Gilbert E.

    2004-01-01

    Sequestration of carbon as a stable mineral carbonate has been proposed to mitigate environmental concerns that carbon dioxide may with time escape from its sequestered matrix using alternative sequestration technologies. A method has been developed to prepare stable carbonate products by reacting CO2 with magnesium silicate minerals in aqueous bicarbonate/chloride media at high temperature and pressure. Because this approach is inherently expensive due to slow reaction rates and high capital costs, studies were conducted to improve the reaction rates through mineral pretreatment steps and to cut expenses through improved reactor technology. An overview is given for the estimated cost of the process including sensitivity to grinding and heating as pretreatment options for several mineral feedstocks. The energy costs are evaluated for each pretreatment in terms of net carbon avoided. New studies with a high-temperature, high-pressure flow-loop reactor have yielded information on overcoming kinetic barriers experienced with processing in stirred autoclave reactors. Repeated tests with the flow-loop reactor have yielded insights on wear and failure of system components, on challenges to maintain and measure flow, and for better understanding of the reaction mechanism

  10. A Small-Scale Capsule Test for Investigating the Sodium-Carbon Dioxide Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Kim, B. H.; Choi, J. H.; Suk, S. D.; Kim, J. M.; Choi, B. H.; Kim, B. H.; Hahn, D. H

    2007-01-15

    The utilization of modular sodium-to-supercritical CO{sub 2} heat exchangers may yield significant improvements for an overall plant energy utilization. The consequences of a failure of the sodium CO{sub 2} heat exchanger boundary, however, would involve the blowdown and intermixing of high-pressure CO{sub 2} in a sodium pool, causing a pressurization which may threaten the structural integrity of the heat exchanger. Available data seems to indicate that the chemical reaction between sodium and CO{sub 2} would likely produce sodium oxides, sodium carbonate, carbon and carbon monoxide. Information on the kinetics of the sodium-CO{sub 2} reaction is virtually non-existent.

  11. Applications of Novel Carbon/AlPO4 Hybrid-Coated H2Ti12O25 as a High-Performance Anode for Cylindrical Hybrid Supercapacitors.

    Science.gov (United States)

    Lee, Jeong-Hyun; Lee, Seung-Hwan

    2016-10-26

    The hybrid supercapacitor using carbon/AlPO 4 hybrid-coated H 2 Ti 12 O 25 /activated carbon is fabricated as a cylindrical cell and investigated against electrochemical performances. The hybrid coating shows that the conductivity for the electron and Li ion is superior and it prevented active material from HF attack. Consequently, carbon/AlPO 4 hybrid-coated H 2 Ti 12 O 25 shows enhanced rate capability and long-term cycle life. Also, the hybrid coating inhibits swelling phenomenon caused by gas generated as decomposition reaction of electrolyte. Therefore, the hybrid supercapacitor using carbon/AlPO 4 hybrid-coated H 2 Ti 12 O 25 /activated carbon can be applied to an energy storage system that requires a long-term life.

  12. Fluorescent Carbon Dots Derived from Maillard Reaction Products: Their Properties, Biodistribution, Cytotoxicity, and Antioxidant Activity.

    Science.gov (United States)

    Li, Dongmei; Na, Xiaokang; Wang, Haitao; Xie, Yisha; Cong, Shuang; Song, Yukun; Xu, Xianbing; Zhu, Bei-Wei; Tan, Mingqian

    2018-02-14

    Food-borne nanoparticles have received great attention because of their unique physicochemical properties and potential health risk. In this study, carbon dots (CDs) formed during one of the most important chemical reactions in the food processing field, the Maillard reaction from the model system including glucose and lysine, were investigated. The CDs purified from Maillard reaction products emitted a strong blue fluorescence under ultraviolet light with a fluorescent quantum yield of 16.30%. In addition, they were roughly spherical, with sizes of around 4.3 nm, and mainly composed of carbon, oxygen, hydrogen, and nitrogen. Their surface groups such as hydroxyl, amino, and carboxyl groups were found to possibly enable CDs to scavenge DPPH and hydroxyl radicals. Furthermore, the cytotoxicity assessment of CDs showed that they could readily enter HepG2 cells while causing negligible cell death at low concentration. However, high CDs concentrations were highly cytotoxic and led to cell death via interference of the glycolytic pathway.

  13. Electro-deposition of Pd on carbon paper and Ni foam via surface limited redox-replacement reaction for oxygen reduction reaction

    CSIR Research Space (South Africa)

    Modibedi, RM

    2014-05-01

    Full Text Available Pd nanostructured catalysts were electrodeposited by surface-limited redox replacement reactions usingthe electrochemical atomic layer deposition technique. Carbon paper and Ni foam were used as substratesfor the electrodeposition of the metal...

  14. Exploration of the Role of Heat Activation in Enhancing Serpentine Carbon Sequestration Reactions

    International Nuclear Information System (INIS)

    McKelvy, M.J.; Chizmeshya, A.V.G.; Diefenbacher, J.; Bearat, H.; Wolf, G.

    2005-01-01

    As compared with other candidate carbon sequestration technologies, mineral carbonation offers the unique advantage of permanent disposal via geologically stable and environmentally benign carbonates. The primary challenge is the development of an economically viable process. Enhancing feedstock carbonation reactivity is key. Heat activation dramatically enhances aqueous serpentine carbonation reactivity. Although the present process is too expensive to implement, the materials characteristics and mechanisms that enhance carbonation are of keen interest for further reducing cost. Simultaneous thermogravimetric and differential thermal analysis (TGA/DTA) of the serpentine mineral lizardite was used to isolate a series of heat-activated materials as a function of residual hydroxide content at progressively higher temperatures. Their structure and composition are evaluated via TGA/DTA, X-ray powder diffraction (including phase analysis), and infrared analysis. The meta-serpentine materials that were observed to form ranged from those with longer range ordering, consistent with diffuse stage-2 like interlamellar order, to an amorphous component that preferentially forms at higher temperatures. The aqueous carbonation reaction process was investigated for representative materials via in situ synchrotron X-ray diffraction. Magnesite was observed to form directly at 15 MPa CO 2 and at temperatures ranging from 100 to 125 C. Carbonation reactivity is generally correlated with the extent of meta-serpentine formation and structural disorder.

  15. Modeling of Sheath Ion-Molecule Reactions in Plasma Enhanced Chemical Vapor Deposition of Carbon Nanotubes

    Science.gov (United States)

    Hash, David B.; Govindan, T. R.; Meyyappan, M.

    2004-01-01

    In many plasma simulations, ion-molecule reactions are modeled using ion energy independent reaction rate coefficients that are taken from low temperature selected-ion flow tube experiments. Only exothermic or nearly thermoneutral reactions are considered. This is appropriate for plasma applications such as high-density plasma sources in which sheaths are collisionless and ion temperatures 111 the bulk p!asma do not deviate significantly from the gas temperature. However, for applications at high pressure and large sheath voltages, this assumption does not hold as the sheaths are collisional and ions gain significant energy in the sheaths from Joule heating. Ion temperatures and thus reaction rates vary significantly across the discharge, and endothermic reactions become important in the sheaths. One such application is plasma enhanced chemical vapor deposition of carbon nanotubes in which dc discharges are struck at pressures between 1-20 Torr with applied voltages in the range of 500-700 V. The present work investigates The importance of the inclusion of ion energy dependent ion-molecule reaction rates and the role of collision induced dissociation in generating radicals from the feedstock used in carbon nanotube growth.

  16. Resonances in the nuclear reactions 15N + 12C and 15N + 16O

    International Nuclear Information System (INIS)

    Monnehan, G.A.

    1987-06-01

    The reaction 12 C + 15 N have been studied at 15 N beam energies between 30 and 70 MeV. For each reaction, about twelve residual nuclei have been identified through the γ-ray detection method. Excitation functions were obtained for the fusion and peripheral channels. Resonances are seen in the channels containing at least one α particle at energies below 50 MeV. At higher energies, strong structures are observed in the direct reaction channels. The evolution of the fusion cross section is well reproduced by a model based on the statistical desexcitation of the compound nucleus if the discrete states of the residual nuclei are taken into account. The favourable observation of resonant phenomena in 15 N induced reactions can be understood in terms of a small number of channels open to the grazing wave. In the range 50 to 60 MeV, there is a strong coupling between the fusion and the direct reaction channels. The occurrence of resonances above E lab = 50 MeV in the peripheral channels is explained with the band crossing and effective barrier models. In the 15 N induced reactions, the absorption of the surface waves is weak [fr

  17. 16O resonances near 4α threshold through 12C(6Li,d) reaction

    International Nuclear Information System (INIS)

    Rodrigues, M. R. D.; Borello-Lewin, T.; Miyake, H.; Horodynski-Matsushigue, L. B.; Duarte, J. L. M.; Rodrigues, C. L.; Faria, P. Neto de; Cunsolo, A.; Cappuzzello, F.; Foti, A.; Agodi, C.; Cavallaro, M.; Napoli, M. di; Ukita, G. M.

    2014-01-01

    Several narrow alpha resonant 16 O states were detected through the 12 C( 6 Li,d) reaction, in the range of 13.5 to 17.5 MeV of excitation energy. The reaction was measured at a bombarding energy of 25.5 MeV employing the São Paulo Pelletron-Enge-Spectrograph facility and the nuclear emulsion technique. Experimental angular distributions associated with natural parity quasi-bound states around the 4α threshold are presented and compared to DWBA predictions. The upper limit for the resonance widths obtained is near the energy resolution (15 keV)

  18. 16O resonances near 4α threshold through 12C (6Li,d ) reaction

    Science.gov (United States)

    Rodrigues, M. R. D.; Borello-Lewin, T.; Miyake, H.; Horodynski-Matsushigue, L. B.; Duarte, J. L. M.; Rodrigues, C. L.; de Faria, P. Neto; Cunsolo, A.; Cappuzzello, F.; Foti, A.; Agodi, C.; Cavallaro, M.; di Napoli, M.; Ukita, G. M.

    2014-11-01

    Several narrow alpha resonant 16O states were detected through the 12C (6Li,d ) reaction, in the range of 13.5 to 17.5 MeV of excitation energy. The reaction was measured at a bombarding energy of 25.5 MeV employing the São Paulo Pelletron-Enge-Spectrograph facility and the nuclear emulsion technique. Experimental angular distributions associated with natural parity quasi-bound states around the 4α threshold are presented and compared to DWBA predictions. The upper limit for the resonance widths obtained is near the energy resolution (15 keV).

  19. Study of reaction mechanism for 12C(14N, 6Li) by angular correlation measurement

    International Nuclear Information System (INIS)

    Goldberg, V.Z.; Golovkov, M.S.; Rogatchev, G.V.; Barrov, S.P.; Zurmuhle, R.W.; Liu, Z.; Benton, D.R.; Miao, Y.; Lee, C.; Wimer, N.G.; Murgatroyd, J.T.; Li, X.

    1999-01-01

    An angular correlation for the reaction 12 C ( 14 N, 6 Li) 20 Ne* (α) populating the 8.78 MeV (6 + ) level in 20 Ne is measured at 48 MeV incident 14 N energy. 6 Li is registered for 0-degree geometry in coincidence with α particles from the 20 Ne excited state decay. The results shows that 20% was the upper limit for the contribution of compound nucleus formation. Possible main direct mechanisms of the reaction are discussed [ru

  20. 27.12 MHz plasma generation in supercritical carbon dioxide

    International Nuclear Information System (INIS)

    Kawashima, Ayato; Toyota, Hiromichi; Nomura, Shinfuku; Takemori, Toshihiko; Mukasa, Shinobu; Maehara, Tsunehiro; Yamashita, Hiroshi

    2007-01-01

    An experiment was conducted for generating high-frequency plasma in supercritical carbon dioxide; it is expected to have the potential for applications in various types of practical processes. It was successfully generated at 6-20 MPa using electrodes mounted in a supercritical cell with a gap of 1 mm. Emission spectra were then measured to investigate the physical properties of supercritical carbon dioxide plasma. The results indicated that while the emission spectra for carbon dioxide and carbon monoxide could be mainly obtained at a low pressure, the emission spectra for atomic oxygen could be obtained in the supercritical state, which increased with the pressure. The temperature of the plasma in supercritical state was estimated to be approximately 6000-7000 K on the assumption of local thermodynamic equilibrium and the calculation results of thermal equilibrium composition in this state showed the increase of atomic oxygen by the decomposition of CO 2

  1. Reduced Reactivity of Amines against Nucleophilic Substitution via Reversible Reaction with Carbon Dioxide

    Directory of Open Access Journals (Sweden)

    Fiaz S. Mohammed

    2015-12-01

    Full Text Available The reversible reaction of carbon dioxide (CO2 with primary amines to form alkyl-ammonium carbamates is demonstrated in this work to reduce amine reactivity against nucleophilic substitution reactions with benzophenone and phenyl isocyanate. The reversible formation of carbamates has been recently exploited for a number of unique applications including the formation of reversible ionic liquids and surfactants. For these applications, reduced reactivity of the carbamate is imperative, particularly for applications in reactions and separations. In this work, carbamate formation resulted in a 67% reduction in yield for urea synthesis and 55% reduction for imine synthesis. Furthermore, the amine reactivity can be recovered upon reversal of the carbamate reaction, demonstrating reversibility. The strong nucleophilic properties of amines often require protection/de-protection schemes during bi-functional coupling reactions. This typically requires three separate reaction steps to achieve a single transformation, which is the motivation behind Green Chemistry Principle #8: Reduce Derivatives. Based upon the reduced reactivity, there is potential to employ the reversible carbamate reaction as an alternative method for amine protection in the presence of competing reactions. For the context of this work, CO2 is envisioned as a green protecting agent to suppress formation of n-phenyl benzophenoneimine and various n-phenyl–n-alky ureas.

  2. Inclusive quasielastic neutrino reactions in 12C and 16O at intermediate energies

    International Nuclear Information System (INIS)

    Singh, S.K.; Oset, E.

    1993-01-01

    Inclusive quasielastic neutrino (antineutrino) reactions on 12 C and 16 O at intermediate energies (50< E<400 MeV) are studied to investigate the effects of the nuclear medium on the total cross section and the energy spectrum of the outgoing leptons. The calculations are done in the local density approximation and various nuclear effects like Pauli blocking, Fermi motion, and strong-interaction renormalizations due to the presence of nucleons are taken into account. The corrections due to Coulomb effects are included which have been hitherto neglected in inclusive reactions. The results presented here are applicable to the inclusive reactions with neutrino beams planned to look for neutrino oscillations in the Los Alamos experiments or the experiments with underground detectors looking for atmospheric or solar flare neutrinos

  3. Fabrication and characterization of reaction bonded silicon carbide/carbon nanotube composites

    International Nuclear Information System (INIS)

    Thostenson, Erik T; Karandikar, Prashant G; Chou, T.-W.

    2005-01-01

    Carbon nanotubes have generated considerable excitement in the scientific and engineering communities because of their exceptional mechanical and physical properties observed at the nanoscale. Carbon nanotubes possess exceptionally high stiffness and strength combined with high electrical and thermal conductivities. These novel material properties have stimulated considerable research in the development of nanotube-reinforced composites (Thostenson et al 2001 Compos. Sci. Technol. 61 1899, Thostenson et al 2005 Compos. Sci. Technol. 65 491). In this research, novel reaction bonded silicon carbide nanocomposites were fabricated using melt infiltration of silicon. A series of multi-walled carbon nanotube-reinforced ceramic matrix composites (NT-CMCs) were fabricated and the structure and properties were characterized. Here we show that carbon nanotubes are present in the as-fabricated NT-CMCs after reaction bonding at temperatures above 1400 deg. C. Characterization results reveal that a very small volume content of carbon nanotubes, as low as 0.3 volume %, results in a 75% reduction in electrical resistivity of the ceramic composites. A 96% decrease in electrical resistivity was observed for the ceramics with the highest nanotube volume fraction of 2.1%

  4. Structure of states in 12Be via the 11Be( d,p) reaction

    Science.gov (United States)

    Kanungo, R.; Gallant, A. T.; Uchida, M.; Andreoiu, C.; Austin, R. A. E.; Bandyopadhyay, D.; Ball, G. C.; Becker, J. A.; Boston, A. J.; Boston, H. C.; Brown, B. A.; Buchmann, L.; Colosimo, S. J.; Clark, R. M.; Cline, D.; Cross, D. S.; Dare, H.; Davids, B.; Drake, T. E.; Djongolov, M.; Finlay, P.; Galinski, N.; Garrett, P. E.; Garnsworthy, A. B.; Green, K. L.; Grist, S.; Hackman, G.; Harkness, L. J.; Hayes, A. B.; Howell, D.; Hurst, A. M.; Jeppesen, H. B.; Leach, K. G.; Macchiavelli, A. O.; Oxley, D.; Pearson, C. J.; Pietras, B.; Phillips, A. A.; Rigby, S. V.; Ruiz, C.; Ruprecht, G.; Sarazin, F.; Schumaker, M. A.; Shotter, A. C.; Sumitharachchi, C. S.; Svensson, C. E.; Tanihata, I.; Triambak, S.; Unsworth, C.; Williams, S. J.; Walden, P.; Wong, J.; Wu, C. Y.

    2010-01-01

    The s-wave neutron fraction of the 0 levels in 12Be has been investigated for the first time through the 11Be(d,p) transfer reaction using a 5 A MeV11Be beam at TRIUMF, Canada. The reaction populated all the known bound states of 12Be. The ground state s-wave spectroscopic factor was determined to be 0.28-0.07+0.03 while that for the long-lived 02+ excited state was 0.73-0.40+0.27. This observation, together with the smaller effective separation energy indicates enhanced probability for an extended density tail beyond the 10Be core for the 02+ excited state compared to the ground state.

  5. Glycerol carbonate in Ferrier reaction: Access to new enantiopure building blocks to develop glycoglycerolipid analogues.

    Science.gov (United States)

    da Costa, Pollyanna Leite Ferreira; Melo, Valentina Nascimento; Guimarães, Bruna Martins; Schuler, Marie; Pimenta, Vanessa; Rollin, Patrick; Tatibouët, Arnaud; de Oliveira, Ronaldo Nascimento

    2016-12-21

    Glycerol carbonate and tri-O-acetyl-D-glucal were used for the synthesis of glycero-functionalized carbohydrates. Ferrier reaction between the two partners afforded the O-glucoside in 84% yield. Spontaneous crystallization yielded 28% of a pure diastereoisomer with the S configuration as determined by X-ray crystallography. Then, the azido-glycerosugar was prepared in two steps: ring opening of the cyclic carbonate with sodium azide and per-acetylation with an excellent yield of 94%. A library of glycoconjugates were prepared using a 1,3-dipolar cycloaddition in yields ranging from 64 to 99%. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Carbon dioxide/methanol conversion cycle based on cascade enzymatic reactions supported on superparamagnetic nanoparticles

    Directory of Open Access Journals (Sweden)

    CATERINA G.C. MARQUES NETTO

    2017-10-01

    Full Text Available ABSTRACT The conversion of carbon dioxide into important industrial feedstock is a subject of growing interest in modern society. A possible way to achieve this goal is by carrying out the CO2/methanol cascade reaction, allowing the recycle of CO2 using either chemical catalysts or enzymes. Efficient and selective reactions can be performed by enzymes; however, due to their low stability, immobilization protocols are required to improve their performance. The cascade reaction to reduce carbon dioxide into methanol has been explored by the authors, using, sequentially, alcohol dehydrogenase (ADH, formaldehyde dehydrogenase (FalDH, and formate dehydrogenase (FDH, powered by NAD+/NADH and glutamate dehydrogenase (GDH as the co-enzyme regenerating system. All the enzymes have been immobilized on functionalized magnetite nanoparticles, and their reactions investigated separately in order to establish the best performance conditions. Although the stepwise scheme led to only 2.3% yield of methanol per NADH; in a batch system under CO2 pressure, the combination of the four immobilized enzymes increased the methanol yield by 64 fold. The studies indicated a successful regeneration of NADH in situ, envisaging a real possibility of using immobilized enzymes to perform the cascade CO2-methanol reaction.

  7. Measurement of the reaction 12C(νμ,μ-)X near threshold

    International Nuclear Information System (INIS)

    Albert, M.; Athanassopoulos, C.; Auerbach, L.B.; Bauer, D.; Bolton, R.; Boyd, B.; Burman, R.L.; Cohen, I.; Caldwell, D.O.; Dieterle, B.D.; Donahue, J.B.; Eisner, A.M.; Fazely, A.; Federspiel, F.J.; Garvey, G.T.; Gunasingha, R.M.; Highland, V.; Hill, J.; Imlay, R.; Johnston, K.; Louis, W.C.; Lu, A.; Mann, A.K.

    1995-01-01

    The reaction 12 C(ν μ ,μ - )X has been measured near threshold using a π + decay-in-flight ν μ beam from the Los Alamos Meson Physics Facility and a massive liquid scintillator neutrino detector (LSND). In the energy region 123.7 ν -40 cm 2 } is more than a factor of 2 lower than that predicted by the Fermi-gas model and by a recent random phase approximation calculation

  8. Photochemical reaction of Si-substituted ethynylsilanes with 1,2-ethanedithiol

    Energy Technology Data Exchange (ETDEWEB)

    Voronkov, M.G.; Brodskaya, E.I.; Kalabin, G.A.; Vlasova, N.N.; Yarosh, O.G.; Zhila, G.Y.

    1985-12-01

    The authors investigate the chief products of the photochemical reactions of Si-substituted ethynylsilanes with 1,2,-ethanedithiol at 60-70 C. It is found that the chief products are 2-triorganylsilyl-substituted 1,4-dithiacyclopentanes and 1,4-dithiacyclohexanes. On lowering the temperature to -30 C, formation of bis (triorganylsilyl)-substituted 1,4,7,10-tetrathiacyclododecanes occurs along with the abo ve-mentioned five- and six-membered heterocycles.

  9. The 12C+α reaction rate from the elastic 16O breakup

    International Nuclear Information System (INIS)

    Kiener, J.; Kraus, L.; Lefebvre, A.; Mittig, W.; Motobayashi, T.; De Oliveira-Santos, F.; Stephan, C.; Thibaud, J.P.

    1997-01-01

    Evidence for direct elastic breakup of 16 O into the α- 12 C continuum with relative energies ranging from 900 to 1800 keV has been obtained in the scattering of 1527 MeV 16 O projectiles off 208 Pb. An interpretation of E2 breakup including nuclear and Coulomb contributions leads to reduced electromagnetic transition probabilities and astrophysical S E2 factors in reasonable agreement with direct measurements, showing that the method can be applied to extract the E2 part of the 12 C(α,γ) reaction rate. (orig.)

  10. Interface conditions for fast-reaction fronts in wet porous mineral materials: the case of concrete carbonation

    NARCIS (Netherlands)

    Muntean, A.; Böhm, M.

    2009-01-01

    Reaction–diffusion processes, where slow diffusion balances fast reaction, usually exhibit internal loci where the reactions are concentrated. Some modeling and simulation aspects of using kinetic free-boundary conditions to drive fast carbonation reaction fronts into unsaturated porous cement-based

  11. The effect of toxic carbon source on the reaction of activated sludge in the batch reactor.

    Science.gov (United States)

    Wu, Changyong; Zhou, Yuexi; Zhang, Siyu; Xu, Min; Song, Jiamei

    2018-03-01

    The toxic carbon source can cause higher residual effluent dissolved organic carbon than easily biodegraded carbon source in activated sludge process. In this study, an integrated activated sludge model is developed as the tool to understand the mechanism of toxic carbon source (phenol) on the reaction, regarding the carbon flows during the aeration period in the batch reactor. To estimate the toxic function of phenol, the microbial cells death rate (k death ) is introduced into the model. The integrated model was calibrated and validated by the experimental data and it was found the model simulations matched the all experimental measurements. In the steady state, the toxicity of phenol can result in higher microbial cells death rate (0.1637 h -1 vs 0.0028 h -1 ) and decay rate coefficient of biomass (0.0115 h -1 vs 0.0107 h -1 ) than acetate. In addition, the utilization-associated products (UAP) and extracellular polymeric substances (EPS) formation coefficients of phenol are higher than that of acetate, indicating that more carbon flows into the extracellular components, such as soluble microbial products (SMP), when degrading toxic organics. In the non-steady state of feeding phenol, the yield coefficient for growth and maximum specific growth rate are very low in the first few days (1-10 d), while the decay rate coefficient of biomass and microbial cells death rate are relatively high. The model provides insights into the difference of the dynamic reaction with different carbon sources in the batch reactor. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. The GLOBE Carbon Project: Integrating the Science of Carbon Cycling and Climate Change into K-12 Classrooms.

    Science.gov (United States)

    Ollinger, S. V.; Silverberg, S.; Albrechtova, J.; Freuder, R.; Gengarelly, L.; Martin, M.; Randolph, G.; Schloss, A.

    2007-12-01

    The global carbon cycle is a key regulator of the Earth's climate and is central to the normal function of ecological systems. Because rising atmospheric CO2 is the principal cause of climate change, understanding how ecosystems cycle and store carbon has become an extremely important issue. In recent years, the growing importance of the carbon cycle has brought it to the forefront of both science and environmental policy. The need for better scientific understanding has led to establishment of numerous research programs, such as the North American Carbon Program (NACP), which seeks to understand controls on carbon cycling under present and future conditions. Parallel efforts are greatly needed to integrate state-of-the-art science on the carbon cycle and its importance to climate with education and outreach efforts that help prepare society to make sound decisions on energy use, carbon management and climate change adaptation. Here, we present a new effort that joins carbon cycle scientists with the International GLOBE Education program to develop carbon cycle activities for K-12 classrooms. The GLOBE Carbon Cycle project is focused on bringing cutting edge research and research techniques in the field of terrestrial ecosystem carbon cycling into the classroom. Students will collect data about their school field site through existing protocols of phenology, land cover and soils as well as new protocols focused on leaf traits, and ecosystem growth and change. They will also participate in classroom activities to understand carbon cycling in terrestrial ecosystems, these will include plant- a-plant experiments, hands-on demonstrations of various concepts, and analysis of collected data. In addition to the traditional GLOBE experience, students will have the opportunity to integrate their data with emerging and expanding technologies including global and local carbon cycle models and remote sensing toolkits. This program design will allow students to explore research

  13. Silver-catalyzed formal inverse electron-demand Diels-Alder reaction of 1,2-diazines and siloxy alkynes.

    Science.gov (United States)

    Türkmen, Yunus E; Montavon, Timothy J; Kozmin, Sergey A; Rawal, Viresh H

    2012-06-06

    A highly effective silver-catalyzed formal inverse electron-demand Diels-Alder reaction of 1,2-diazines and siloxy alkynes has been developed. The reactions provide ready access to a wide range of siloxy naphthalenes and anthracenes, which are formed in good to high yields, under mild reaction conditions, using low catalyst loadings.

  14. Combined steam and carbon dioxide reforming of methane and side reactions: Thermodynamic equilibrium analysis and experimental application

    International Nuclear Information System (INIS)

    Jang, Won-Jun; Jeong, Dae-Woon; Shim, Jae-Oh; Kim, Hak-Min; Roh, Hyun-Seog; Son, In Hyuk; Lee, Seung Jae

    2016-01-01

    Highlights: • Selected variables have a significant influence on yields of synthesis gas. • (CO_2 + H_2O)/CH_4 affects the temperature which can achieve the maximum conversion. • Coke is formed at low temperatures even with excess oxidizing agent. • The occurrence of RWGS becomes critical in real chemical reactions. • Equilibrium conversions are maintained for 500 h without detectable deactivation. - Abstract: Thermodynamic equilibrium analysis of the combined steam and carbon dioxide reforming of methane (CSCRM) and side reactions was performed using total Gibbs free energy minimization. The effects of (CO_2 + H_2O)/CH_4 ratio (0.9–2.9), CO_2:H_2O ratio (3:1–1:3), and temperature (500–1000 °C) on the equilibrium conversions, yields, coke yield, and H_2/CO ratio were investigated. A (CO_2 + H_2O)/CH_4 ratio greater than 1.2, a CO_2:H_2O ratio of 1:2.1, and a temperature of at least 850 °C are preferable reaction conditions for the synthesis gas preparation in the gas to liquid process. Simulated conditions were applied to the CSCRM reaction and the experimental data were compared with the thermodynamic equilibrium results. The thermodynamic equilibrium results were mostly consistent with the experimental data, but the reverse water gas shift reaction rapidly occurred in the real chemical reaction and under excess oxidizing agent conditions. In addition, a long-term stability test (under simulated conditions) showed that the equilibrium conversion was maintained for 500 h and that the coke formation on the used catalyst was not observed.

  15. Bio-inspired carbon electro-catalysis for the oxygen reduction reaction

    OpenAIRE

    Preuss, Kathrin; Kannuchamy, Vasanth Kumar; Marinovic, Adam; Isaacs, Mark; Wilson, Karen; Abrahams, Isaac; Titirici, Maria-Magdalena

    2016-01-01

    We report the synthesis, characterisation and catalytic performance of two nature-inspired biomass-derived electro-catalysts for the oxygen reduction reaction in fuel cells. The catalysts were prepared via pyrolysis of a real food waste (lobster shells) or by mimicking the composition of lobster shells using chitin and CaCO3 particles followed by acid washing. The simplified model of artificial lobster was prepared for better reproducibility. The calcium carbonate in both samples acts as a po...

  16. Synthesis of 2D Nitrogen-Doped Mesoporous Carbon Catalyst for Oxygen Reduction Reaction

    Directory of Open Access Journals (Sweden)

    Zhipeng Yu

    2017-02-01

    Full Text Available 2D nitrogen-doped mesoporous carbon (NMC is synthesized by using a mesoporous silica film as hard template, which is then investigated as a non-precious metal catalyst for the oxygen reduction reaction (ORR. The effect of the synthesis conditions on the silica template and carbon is extensively investigated. In this work, we employ dual templates—viz. graphene oxide and triblock copolymer F127—to control the textural features of a 2D silica film. The silica is then used as a template to direct the synthesis of a 2D nitrogen-doped mesoporous carbon. The resultant nitrogen-doped mesoporous carbon is characterized by transmission electron microscopy (TEM, nitrogen ad/desorption isotherms, X-ray photoelectron spectroscopy (XPS, cyclic voltammetry (CV, and rotating disk electrode measurements (RDE. The electrochemical test reveals that the obtained 2D-film carbon catalyst yields a highly electrochemically active surface area and superior electrocatalytic activity for the ORR compared to the 3D-particle. The superior activity can be firstly attributed to the difference in the specific surface area of the two catalysts. More importantly, the 2D-film morphology makes more active sites accessible to the reactive species, resulting in a much higher utilization efficiency and consequently better activity. Finally, it is noted that all the carbon catalysts exhibit a higher ORR activity than a commercial Pt catalyst, and are promising for use in fuel cells.

  17. [Involvement of carbonate/bicarbonate ions in the superoxide-generating reaction of adrenaline autoxidation].

    Science.gov (United States)

    Sirota, T V

    2015-01-01

    An important role of carbonate/bicarbonate ions has been recognized in the superoxide generating reaction of adrenaline autooxidation in an alkaline buffer (a model of quinoid adrenaline oxidation in the body). It is suggested that these ions are directly involved not only in formation of superoxide anion radical (О(2)(-)) but also other radicals derived from the carbonate/bicarbonate buffer. Using various buffers it was shown that the rate of accumulation of adrenochrome, the end product of adrenaline oxidation, and the rate of О(2)(-)· formation depend on concentration of carbonate/bicarbonate ions in the buffer and that these ions significantly accelerate adrenaline autooxidation thus demonstrating prooxidant properties. The detectable amount of diformazan, the product of nitro blue tetrazolium (NBT) reduction, was significantly higher than the amount of adrenochrome formed; taking into consideration the literature data on О(2)(-)· detection by NBT it is suggested that adrenaline autooxidation is accompanied by one-electron reduction not only of oxygen dissolved in the buffer and responsible for superoxide formation but possible carbon dioxide also dissolved in the buffer as well as carbonate/bicarbonate buffer components leading to formation of corresponding radicals. The plots of the dependence of the inhibition of adrenochrome and diformazan formation on the superoxide dismutase concentration have shown that not only superoxide radicals are formed during adrenaline autooxidation. Since carbonate/bicarbonate ions are known to be universally present in the living nature, their involvement in free radical processes proceeding in the organism is discussed.

  18. Total reaction cross section for 12C+16O below the Coulomb barrier

    International Nuclear Information System (INIS)

    Cujec, B.; Barnes, C.A.

    1976-01-01

    The energy dependence of the total reaction cross section, sigma(E), for 12 C+ 16 0 has been measured over the range Esub(c.m.)=4-12 MeV, by detecting γ-rays from the various possible residual nuclei with two large NaI(Tl) detectors placed close to the target. This technique for measuring total reaction cross sections was explored in some detail and shown to yield reliable values for sigma(E). Although the principal emphasis of this work was placed on obtaining reliable cross sections, a preliminary study has been made of the suitability of various methods for extrapolating the cross section to still lower energies. The statistical model provides a good fit with a reasonable value for the strength function, 2 >/ =6.8x10 -2 , over the range Esub(c.m.)=6.5-12 MeV, but predicts cross sections which are much too large for Esub(c.m.)<6.5 MeV. Optical model fits at low energies are especially sensitive to the radius and diffuseness of the imaginary component of the potential and, since these are still poorly known at present, such extrapolations may be wrong by orders of magnitude. A simple barrier penetration model gives a moderately good fit to the data and seems to provide the safest extrapolation to lower energies at the present time. It is clear, however, that our knowledge of the heavy-ion reaction mechanism at low energies is incomplete, and that cross-section measurements at still lower energies are needed to establish the correct procedure for extrapolating heavy-ion reaction cross sections to low energies. (Auth.)

  19. Electrochemical characteristics of vanadium redox reactions on porous carbon electrodes for microfluidic fuel cell applications

    International Nuclear Information System (INIS)

    Lee, Jin Wook; Hong, Jun Ki; Kjeang, Erik

    2012-01-01

    Microfluidic vanadium redox fuel cells are membraneless and catalyst-free fuel cells comprising a microfluidic channel network with two porous carbon electrodes. The anolyte and catholyte for fuel cell operation are V(II) and V(V) in sulfuric acid based aqueous solution. In the present work, the electrochemical characteristics of the vanadium redox reactions are investigated on commonly used porous carbon paper electrodes and compared to a standard solid graphite electrode as baseline. Half-cell electrochemical impedance spectroscopy is applied to measure the overall ohmic resistance and resistivity of the electrodes. Kinetic parameters for both V(II) and V(V) discharging reactions are extracted from Tafel plots and compared for the different electrodes. Cyclic voltammetry techniques reveal that the redox reactions are irreversible and that the magnitudes of peak current density vary significantly for each electrode. The obtained kinetic parameters for the carbon paper are implemented into a numerical simulation and the results show a good agreement with measured polarization curves from operation of a microfluidic vanadium redox fuel cell employing the same material as flow-through porous electrodes. Recommendations for microfluidic fuel cell design and operation are provided based on the measured trends.

  20. NMR studies of stock process water and reaction pathways in hydrothermal carbonization of furfural residue

    Directory of Open Access Journals (Sweden)

    Fen Yue

    2018-04-01

    Full Text Available Hydrothermal carbonization (HTC is a valuable approach to convert furfural residue (FR into carbon material. The prepared biochars are usually characterized comprehensively, while the stock process water still remains to be studied in detail. Herein, a NMR study of the main components in stock process water generated at different HTC reaction conditions was reported. Various qualitative and quantitative NMR techniques (1H and 13C NMR, 1H–1H COSY and 1H13C HSQC etc. especially 1D selective gradient total correlation spectroscopy (TOCSY NMR were strategically applied in the analysis of HTC stock process water. Without separation and purification, it was demonstrated that the main detectable compounds are 5-hydroxymethylfurfural, formic acid, methanol, acetic acid, levulinic acid, glycerol, hydroxyacetone and acetaldehyde in this complicate mixture. Furthermore, the relationship between the concentration of major products and the reaction conditions (180–240 °C at 8 h, and 1–24 h at 240 °C was established. Finally, reasonable reaction pathways for hydrothermal conversion of FR were proposed based on this result and our previously obtained characteristics of biochars. The routine and challenging NMR methods utilized here would be an alternative other than HPLC or GC for biomass conversion research and can be extended to more studies. Keywords: NMR, Hydrothermal carbonization, Furfural residue, Stock process water

  1. Nitrogen-Doped Carbon Nanotube and Graphene Materials for Oxygen Reduction Reactions

    Directory of Open Access Journals (Sweden)

    Qiliang Wei

    2015-09-01

    Full Text Available Nitrogen-doped carbon materials, including nitrogen-doped carbon nanotubes (NCNTs and nitrogen-doped graphene (NG, have attracted increasing attention for oxygen reduction reaction (ORR in metal-air batteries and fuel cell applications, due to their optimal properties including excellent electronic conductivity, 4e− transfer and superb mechanical properties. Here, the recent progress of NCNTs- and NG-based catalysts for ORR is reviewed. Firstly, the general preparation routes of these two N-doped carbon-allotropes are introduced briefly, and then a special emphasis is placed on the developments of both NCNTs and NG as promising metal-free catalysts and/or catalyst support materials for ORR. All these efficient ORR electrocatalysts feature a low cost, high durability and excellent performance, and are thus the key factors in accelerating the widespread commercialization of metal-air battery and fuel cell technologies.

  2. Carbon Dioxide Utilization by the Five-Membered Ring Products of Cyclometalation Reactions

    Science.gov (United States)

    Omae, Iwao

    2016-01-01

    In carbon dioxide utilization by cyclometalated five-membered ring products, the following compounds are used in four types of applications: 1. 2-Phenylpyrazole iridium compounds, pincer phosphine iridium compounds and 2-phenylimidazoline iridium compounds are used as catalysts for both formic acid production from CO2 and H2, and hydrogen production from the formic acid. This formic acid can be a useful agent for H2 production and storage for fuel cell electric vehicles. 2. Other chemicals, e.g., dimethyl carbonate, methane, methanol and CO, are produced with dimethylaminomethylphenyltin compounds, pincer phosphine iridium compounds, pincer phosphine nickel compound and ruthenium carbene compound or 2-phenylpyridine iridium compounds, and phenylbenzothiazole iridium compounds as the catalysts for the reactions with CO2. 3. The five-membered ring intermediates of cyclometalation reactions with the conventional substrates react with carbon dioxide to afford their many types of carboxylic acid derivatives. 4. Carbon dioxide is easily immobilized at room temperature with immobilizing agents such as pincer phosphine nickel compounds, pincer phosphine palladium compounds, pincer N,N-dimethylaminomethyltin compounds and tris(2-pyridylthio)methane zinc compounds. PMID:28503084

  3. Determination of {sup 55}Mn(n,γ){sup 56}Mn reaction cross-section at the neutron energies of 1.12, 2.12, 3.12 and 4.12 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Vansola, Vibha; Mukherjee, Surjit [M.S. University of Baroda, Vadodara (India). Dept. of Physics; Naik, Haladhara [Bhabha Atomic Research Center, Mumbai (India). Radiochemistry Div.; Suryanarayana, Saraswatula Venkata [Bhabha Atomic Research Center, Mumbai (India). Nuclear Physics Div.; Ghosh, Reetuparna; Badwar, Sylvia; Lawriniang, Bioletty Mary [North Eastern Hill Univ., Meghalaya (India). Dept. of Physics; Sheela, Yerraguntla Santhi [Manipal Univ. (India). Dept. of Statistics

    2016-07-01

    The {sup 55}Mn(n,γ){sup 56}Mn reaction cross-sections at the neutron energies of 1.12, 2.12, 3.12 and 4.12 MeV were determined by using activation and off-line γ-ray spectrometric technique. The neutron energies of 1.12 and 2.12 MeV were generated from the {sup 7}Li(p,n) reaction by using the proton energies of 3 and 4 MeV from the folded tandem ion beam accelerator (FOTIA) at BARC. For the neutron energies of 3.12 and 4.12 MeV, the proton energies used were 5 and 6 MeV from the Pelletron facility at TIFR, Mumbai. The {sup 115}In(n,γ){sup 116m}In reaction cross-section was used as the neutron flux monitor. The {sup 55}Mn(n,γ){sup 56}Mn reaction cross-section at the neutron energies of 4.12 MeV are reported for the first time, whereas at 1.12, 2.12 and 3.12 MeV, they are in between the literature data. The {sup 55}Mn(n,γ){sup 56}Mn reaction cross-section was also calculated theoretically by using the computer code TALYS 1.6 and EMPIRE 3.2.2. The experimental data of present work are found to be in between the theoretical values of TALYS and EMPIRE.

  4. Spin alignment and density matrix measurement in 28Si + 12C orbiting reaction

    International Nuclear Information System (INIS)

    Ray, A.; Shapira, D.; Halbert, M.L.; Gomez del Campo, J.; Kim, H.J.; Sullivan, J.P.; Shivakumar, B.; Mitchell, J.

    1990-01-01

    Gamma-ray angular correlations have been measured for the strongly damped reactions 12 C( 28 Si, 12 C) 28 Si between θ cm = (120 degree - 160 degree) for E cm = 43.5 and 48 MeV. We find that the density matrices for the 12 C(2 1 + ) and 28 Si states are almost diagonal with respect to the direction of motion of the outgoing particle. The measured density matrices and spin alignments are consistent with the picture of formation of a long-lived dinuclear complex undergoing orbiting, bending and wriggling motions, but not with those obtained from statistical compound nucleus or sticking model calculations. 17 refs., 2 figs., 1 tab

  5. Dissolution and secondary mineral precipitation in basalts due to reactions with carbonic acid

    Science.gov (United States)

    Kanakiya, Shreya; Adam, Ludmila; Esteban, Lionel; Rowe, Michael C.; Shane, Phil

    2017-06-01

    One of the leading hydrothermal alteration processes in volcanic environments is when rock-forming minerals with high concentrations of iron, magnesium, and calcium react with CO2 and water to form carbonate minerals. This is used to the advantage of geologic sequestration of anthropogenic CO2. Here we experimentally investigate how mineral carbonation processes alter the rock microstructure due to CO2-water-rock interactions. In order to characterize these changes, CO2-water-rock alteration in Auckland Volcanic Field young basalts (less than 0.3 Ma) is studied before and after a 140 day reaction period. We investigate how whole core basalts with similar geochemistry but different porosity, permeability, pore geometry, and volcanic glass content alter due to CO2-water-rock reactions. Ankerite and aluminosilicate minerals precipitate as secondary phases in the pore space. However, rock dissolution mechanisms are found to dominate this secondary mineral precipitation resulting in an increase in porosity and decrease in rigidity of all samples. The basalt with the highest initial porosity and volcanic glass volume shows the most secondary mineral precipitation. At the same time, this sample exhibits the greatest increase in porosity and permeability, and a decrease in rock rigidity post reaction. For the measured samples, we observe a correlation between volcanic glass volume and rock porosity increase due to rock-fluid reactions. We believe this study can help understand the dynamic rock-fluid interactions when monitoring field scale CO2 sequestration projects in basalts.

  6. Intramolecular energy transfer and mode-specific effects in unimolecular reactions of 1,2-difluoroethane

    Science.gov (United States)

    Raff, Lionel M.

    1989-06-01

    The unimolecular decomposition reactions of 1,2-difluoroethane upon mode-specific excitation to a total internal energy of 7.5 eV are investigated using classical trajectory methods and a previously formulated empirical potential-energy surface. The decomposition channels for 1,2-difluoroethane are, in order of importance, four-center HF elimination, C-C bond rupture, and hydrogen-atom dissociation. This order is found to be independent of the particular vibrational mode excited. Neither fluorine-atom nor F2 elimination reactions are ever observed even though these dissociation channels are energetically open. For four-center HF elimination, the average fraction of the total energy partitioned into internal HF motion varies between 0.115-0.181 depending upon the particular vibrational mode initially excited. The internal energy of the fluoroethylene product lies in the range 0.716-0.776. Comparison of the present results with those previously obtained for a random distribution of the initial 1,2-difluoroethane internal energy [J. Phys. Chem. 92, 5111 (1988)], shows that numerous mode-specific effects are present in these reactions in spite of the fact that intramolecular energy transfer rates for this system are 5.88-25.5 times faster than any of the unimolecular reaction rates. Mode-specific excitation always leads to a total decomposition rate significantly larger than that obtained for a random distribution of the internal energy. Excitation of different 1,2-difluoroethane vibrational modes is found to produce as much as a 51% change in the total decomposition rate. Mode-specific effects are also seen in the product energy partitioning. The rate coefficients for decomposition into the various channels are very sensitive to the particular mode excited. A comparison of the calculated mode-specific effects with the previously determined mode-to-mode energy transfer rate coefficients [J. Chem. Phys. 89, 5680 (1988)] shows that, to some extent, the presence of mode

  7. Synthesis of propylene carbonate from urea and propylene glycol over zinc oxide: A homogeneous reaction

    Directory of Open Access Journals (Sweden)

    Dengfeng Wang

    2014-11-01

    Full Text Available In this work, several metal oxides and zinc salts were used to catalyze propylene carbonate (PC synthesis from urea and propylene glycol (PG. According to the results of catalytic test and characterization, the catalytic pattern of ZnO was different from that of other metal oxides such as CaO, MgO and La2O3, but similar to that of zinc salts. In fact, the leaching of Zn species took place during reaction for ZnO. And ZnO was found to be the precursor of homogenous catalyst for reaction of urea and PG. Thus, the relationship between the amount of dissolved zinc species and the catalytic performance of employed ZnO was revealed. In addition, a possible reaction mechanism over ZnO was discussed based on the catalytic runs and the characterization of XRD, FTIR, and element analysis.

  8. A novel reaction catalysed by active carbons production of dichloromethane from phosgene and formaldehyde

    Energy Technology Data Exchange (ETDEWEB)

    Ryan, T A; Stacey, M H

    1984-08-01

    A variety of Activated charcoals have been found to catalyse a reaction between phosgene and formaldehyde. In a continuous flow fluidized bed reactor, the reaction rate reaches a broad maximum near 170/sup 0/C where the selectivity is consistent with the stoichiometry. The reaction proceeds via a strongly adsorbed intermediate which has been identified as chloromethyl chloroformate. This ester is an adduct of formaldehyde and phosgen and forms rapidly above 100/sup 0/C in co-adsorption/desorption experiments. It decomposes rapidly 170/sup 0/C without significant desorption of the intact molecule to give the observed products dichloromethane and carbon dioxide. Under steady-state conditions the rate-determining step is the formation of this ester so that it is normally only present on the surface at low coverages; hence it is not observable in the gas phase. The catalysis is probably due to the presence of polar acid or base sites on the surface of the activated charcoals.

  9. Interfacial enhancement of carbon fiber/nylon 12 composites by grafting nylon 6 to the surface of carbon fiber

    Science.gov (United States)

    Hui, Chen; Qingyu, Cai; Jing, Wu; Xiaohong, Xia; Hongbo, Liu; Zhanjun, Luo

    2018-05-01

    Nylon 6 (PA6) grafted onto carbon fiber (CF) after chemical oxidation treatment was in an attempt to reinforce the mechanical properties of carbon fiber composites. Scanning electronic microscopy (SEM), Fourier transform infrared analysis (FT-IR), X-ray photoelectron spectroscope (XPS) and thermogravimetric analysis (TG) were selected to characterize carbon fibers with different surface treated. Experimental results showed that PA6 was grafted uniformly on the fiber surface through the anionic polymerization. A large number of functional groups were introduced to the fiber surface and the surface roughness was increased. After grafting PA6 on the oxidized carbon fibers, it played an important role on improving the interfacial adhesion between the fibers and the matrix by improving PA12 wettability, increasing chemical bonding and mechanical interlocking. Compared with the desized CF composites, the tensile strength of PA6-CF/PA12 composites was increased by 30.8% from 53.9 MPa to 70.2 MPa. All results indicated that grafting PA6 onto carbon fiber surface was an effective method to enhance the mechanical strength of carbon fiber/nylon 12 composites.

  10. Thermodynamic Data for Geochemical Modeling of Carbonate Reactions Associated with CO2 Sequestration – Literature Review

    Energy Technology Data Exchange (ETDEWEB)

    Krupka, Kenneth M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Cantrell, Kirk J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); McGrail, B. Peter [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2010-09-01

    Permanent storage of anthropogenic CO2 in deep geologic formations is being considered as a means to reduce the concentration of atmospheric CO2 and thus its contribution to global climate change. To ensure safe and effective geologic sequestration, numerous studies have been completed of the extent to which the CO2 migrates within geologic formations and what physical and geochemical changes occur in these formations when CO2 is injected. Sophisticated, computerized reservoir simulations are used as part of field site and laboratory CO2 sequestration studies. These simulations use coupled multiphase flow-reactive chemical transport models and/or standalone (i.e., no coupled fluid transport) geochemical models to calculate gas solubility, aqueous complexation, reduction/oxidation (redox), and/or mineral solubility reactions related to CO2 injection and sequestration. Thermodynamic data are critical inputs to modeling geochemical processes. The adequacy of thermodynamic data for carbonate compounds has been identified as an important data requirement for the successful application of these geochemical reaction models to CO2 sequestration. A review of thermodynamic data for CO2 gas and carbonate aqueous species and minerals present in published data compilations and databases used in geochemical reaction models was therefore completed. Published studies that describe mineralogical analyses from CO2 sequestration field and natural analogue sites and laboratory studies were also reviewed to identify specific carbonate minerals that are important to CO2 sequestration reactions and therefore require thermodynamic data. The results of the literature review indicated that an extensive thermodynamic database exists for CO2 and CH4 gases, carbonate aqueous species, and carbonate minerals. Values of ΔfG298° and/or log Kr,298° are available for essentially all of these compounds. However, log Kr,T° or heat capacity values at temperatures above 298 K exist for less than

  11. Thermodynamic Data for Geochemical Modeling of Carbonate Reactions Associated with CO2 Sequestration - Literature Review

    International Nuclear Information System (INIS)

    Krupka, Kenneth M.; Cantrell, Kirk J.; McGrail, B. Peter

    2010-01-01

    Permanent storage of anthropogenic CO 2 in deep geologic formations is being considered as a means to reduce the concentration of atmospheric CO 2 and thus its contribution to global climate change. To ensure safe and effective geologic sequestration, numerous studies have been completed of the extent to which the CO 2 migrates within geologic formations and what physical and geochemical changes occur in these formations when CO 2 is injected. Sophisticated, computerized reservoir simulations are used as part of field site and laboratory CO 2 sequestration studies. These simulations use coupled multiphase flow-reactive chemical transport models and/or standalone (i.e., no coupled fluid transport) geochemical models to calculate gas solubility, aqueous complexation, reduction/oxidation (redox), and/or mineral solubility reactions related to CO 2 injection and sequestration. Thermodynamic data are critical inputs to modeling geochemical processes. The adequacy of thermodynamic data for carbonate compounds has been identified as an important data requirement for the successful application of these geochemical reaction models to CO 2 sequestration. A review of thermodynamic data for CO 2 gas and carbonate aqueous species and minerals present in published data compilations and databases used in geochemical reaction models was therefore completed. Published studies that describe mineralogical analyses from CO 2 sequestration field and natural analogue sites and laboratory studies were also reviewed to identify specific carbonate minerals that are important to CO 2 sequestration reactions and therefore require thermodynamic data. The results of the literature review indicated that an extensive thermodynamic database exists for CO 2 and CH 4 gases, carbonate aqueous species, and carbonate minerals. Values of Δ f G 298 o and/or log K r,298 o are available for essentially all of these compounds. However, log K r,T o or heat capacity values at temperatures above 298 K exist

  12. Total reaction cross section and foward glory for 12C + 16O

    International Nuclear Information System (INIS)

    Villari, A.C.C.; Lepine-Szily, A.; Lichtenthaler Filho, R.; Portezan Filho, O.; Obuti, M.M.

    1988-12-01

    A model-independent method is proposed for the determination of the total reaction cross section from elastic angular distributions. This method based on the generalized optical theorem, was applied to 16 complete elastic angular distributions of the system 12 C + 16 O at energies between E CM =8.55 MeV and E CM = 26.74 MeV. Some of the angular distributions were measured at the Sao Paulo Pelletron Laboratory. Angular distributions measured by the Erlangen and Saclay groups were also used. The reaction cross section is compared with fusion measurements and with σ R obtained by indirect methods. The existence and conditions for the observation of the nuclear forward glory scattering are investigated. (author) [pt

  13. Isotopic resolution of fission fragments from 238U + 12C transfer and fusion reactions

    International Nuclear Information System (INIS)

    Caamano, M.; Rejmund, F.; Derkx, X.; Schmidt, K. H.; Andouin, L.; Bacri, C. O.; Barreau, G.; Benlliure, J.; Casarejos, E.; Fernandez-Dominguez, B.; Gaudefroy, L.; Golabek, C.; Jurado, B.; Lemasson, A.; Navin, A.; Rejmund, M.; Roger, T.; Shrivastava, A.; Schmitt, C.; Taieb, J.

    2010-01-01

    Recent results from an experiment at GANIL, performed to investigate the main properties of fission-fragment yields and energy distributions in different fissioning nuclei as a function of the excitation energy, in a neutron-rich region of actinides, are presented. Transfer reactions in inverse kinematics between a 238 U beam and a 12 C target produced different actinides, within a range of excitation energy below 30 MeV. These fissioning nuclei are identified by detecting the target-like recoil, and their kinetic and excitation energy are determined from the reconstruction of the transfer reaction. The large-acceptance spectrometer VAMOS was used to identify the mass, atomic number and charge state of the fission fragments in flight. As a result, the characteristics of the fission-fragment isotopic distributions of a variety of neutron-rich actinides are observed for the first time over the complete range of fission fragments. (authors)

  14. Synthesis of most polyene natural product motifs using just 12 building blocks and one coupling reaction.

    Science.gov (United States)

    Woerly, Eric M; Roy, Jahnabi; Burke, Martin D

    2014-06-01

    The inherent modularity of polypeptides, oligonucleotides and oligosaccharides has been harnessed to achieve generalized synthesis platforms. Importantly, like these other targets, most small-molecule natural products are biosynthesized via iterative coupling of bifunctional building blocks. This suggests that many small molecules also possess inherent modularity commensurate with systematic building block-based construction. Supporting this hypothesis, here we report that the polyene motifs found in >75% of all known polyene natural products can be synthesized using just 12 building blocks and one coupling reaction. Using the same general retrosynthetic algorithm and reaction conditions, this platform enabled both the synthesis of a wide range of polyene frameworks that covered all of this natural-product chemical space and the first total syntheses of the polyene natural products asnipyrone B, physarigin A and neurosporaxanthin b-D-glucopyranoside. Collectively, these results suggest the potential for a more generalized approach to making small molecules in the laboratory.

  15. Energy dependence of fusion evaporation-residue cross sections in the 28Si+12C reaction

    International Nuclear Information System (INIS)

    Vineyard, M.F.; Mateja, J.F.; Beck, C.; Atencio, S.E.; Dennis, L.C.; Frawley, A.D.; Henderson, D.J.; Janssens, R.V.F.; Kemper, K.W.; Kovar, D.G.; Maguire, C.F.; Padalino, S.J.; Prosser, F.W.; Stephans, G.S.F.; Tiede, M.A.; Wilkins, B.D.; Zingarelli, R.A.

    1993-01-01

    Fusion evaporation-residue cross sections for the 28 Si+ 12 C reaction have been measured in the energy range 18≤E c.m. ≤136 MeV using time-of-flight techniques. Velocity distributions of mass-identified reaction products were used to identify evaporation residues and to determine the complete-fusion cross sections at high energies. The data are in agreement with previously established systematics which indicate an entrance-channel mass-asymmetry dependence of the incomplete-fusion evaporation-residue process. The complete-fusion evaporation-residue cross sections and the deduced critical angular momenta are compared with earlier measurements and the predictions of existing models

  16. Structure in the 12C+ 12C and 8Be+16O fission width distribution of 24Mg observed via the reaction 12C(16O,α)24Mg(→X+Y)

    International Nuclear Information System (INIS)

    Lazzarini, A.J.; Steadman, S.G.; Ledoux, R.J.; Sperduto, A.; Young, G.R.; Van Bibber, K.; Cosman, E.R.

    1983-01-01

    Prominent gross and intermediate width structures are observed in the 12 C+ 12 C, 12 C+ 12 C((2 + ), 1 C((2 + )+ 12 C((2 + ), 8 Be+ 16 O, and 8 Be+ 16 O + (3 - , O + ) decay channels following 24 Mg* population via the 12 C( 16 O,α) 24 Mg reaction at E/sub c.m./ = 33 MeV. Evidence that the 12 C( 16 O,α) 24 Mg reaction populates states in 24 Mg which are associated with 12 C+ 12 C resonances is presented in the form of correlation analyses between the α+ 12 C+ 12 C three-body spectra and previously measured 12 C+ 12 C elastic and inelastic excitation functions. Direct determination of 12 C+ 12 C widths from these measurements is obscured by a background of other strong transitions which appear to be present in the 12 C( 16 O,α) 24 Mg singles spectrum

  17. Carbon supported ultrafine gold phosphorus nanoparticles as highly efficient electrocatalyst for alkaline ethanol oxidation reaction

    International Nuclear Information System (INIS)

    Li, Tongfei; Fu, Gengtao; Su, Jiahui; Wang, Yi; Lv, Yinjie; Zou, Xiuyong; Zhu, Xiaoshu; Xu, Lin; Sun, Dongmei; Tang, Yawen

    2017-01-01

    Graphical abstract: We develop a new kind of carbon supported gold-phosphorus (Au-P/C) electrocatalyst by a facile and novel phosphorus reduction method, and demonstrate the Au-P/C is a highly active and stable electrocatalyst for the ethanol oxidation reaction. - Highlights: • Au-P/C catalyst is synthesized by a facile and novel white-phosphorus reduce method. • AuP particles with ultrafine particle-size are uniformly dispersed on carbon support. • Au-P/C catalyst exhibits much higher content of P 0 than reported metal/P catalysts. • Au-P/C catalysts show excellent catalytic properties for ethanol oxidation reaction. - Abstract: Herein, we develop a new kind of carbon supported gold-phosphorus (Au-P/C) electrocatalyst for the alkaline ethanol oxidation reaction (EOR). The Au-P/C catalysts with different Au/P ratio (i.e., AuP/C, Au 3 P 2 /C and Au 4 P 3 /C) can be obtained by a facile and novel hot-reflux method with white phosphorus (P 4 ) as reductant and ethanol as solvent. The crystal structure, composition and particle-size of the Au-P/C catalysts are investigated by X-ray diffraction (XRD), Energy Dispersive Spectrometer (EDS), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), etc. The results demonstrate that Au-P/C catalysts present an alloy phase with the high content of P, ultrafine particle-size and high dispersity on carbon support, which results in excellent electrocatalytic activity and stability towards the EOR compared with that of the free-phosphorus Au/C catalyst. In addition, among the various Au-P/C catalysts with different Au/P ratio, the AuP/C sample exhibits the best electrocatalytic performance in comparison with other Au 3 P 2 /C and Au 4 P 3 /C samples.

  18. Sintering uranium oxide in the reaction product of hydrogen-carbon dioxide mixtures

    International Nuclear Information System (INIS)

    De Hollander, W.R.; Nivas, Y.

    1975-01-01

    Compacted pellets of uranium oxide alone or containing one or more additives such as plutonium dioxide, gadolinium oxide, titanium dioxide, silica, and alumina are heated to 900 to 1599 0 C in the presence of a mixture of hydrogen and carbon dioxide, either alone or with an inert carrier gas and held at the desired temperature in this atmosphere to sinter the pellets. The sintered pellets are then cooled in an atmosphere having an oxygen partial pressure of 10 -4 to 10 -18 atm of oxygen such as dry hydrogen, wet hydrogen, dry carbon monoxide, wet carbon monoxide, inert gases such as nitrogen, argon, helium, and neon and mixtures of ayny of the foregoing including a mixture of hydrogen and carbon dioxide. The ratio of hydrogen to carbon dioxide in the gas mixture fed to the furnace is controlled to give a ratio of oxygen to uranium atoms in the sintered particles within the range of 1.98:1 to about 2.10:1. The water vapor present in the reaction products in the furnace atmosphere acts as a hydrolysis agent to aid removal of fluoride should such impurity be present in the uranium oxide. (U.S.)

  19. Polyaniline-Derived Ordered Mesoporous Carbon as an Efficient Electrocatalyst for Oxygen Reduction Reaction

    Directory of Open Access Journals (Sweden)

    Kai Wan

    2015-06-01

    Full Text Available Nitrogen-doped ordered mesoporous carbon was synthesized by using polyaniline as the carbon source and SBA-15 as the template. The microstructure, composition and electrochemical behavior were extensively investigated by the nitrogen sorption isotherm, X-ray photoelectron spectroscopy, cyclic voltammetry and rotating ring-disk electrode. It is found that the pyrolysis temperature yielded a considerable effect on the pore structure, elemental composition and chemical configuration. The pyrolysis temperature from 800 to 1100 °C yielded a volcano-shape relationship with both the specific surface area and the content of the nitrogen-activated carbon. Electrochemical tests showed that the electrocatalytic activity followed a similar volcano-shape relationship, and the carbon catalyst synthesized at 1000 °C yielded the best performance. The post-treatment in NH3 was found to further increase the specific surface area and to enhance the nitrogen doping, especially the edge-type nitrogen, which favored the oxygen reduction reaction in both acid and alkaline media. The above findings shed light on electrocatalysis and offer more strategies for the controllable synthesis of the doped carbon catalyst.

  20. Measurement of {sup 197}Au(n,γ){sup 198g}Au reaction cross-section at the neutron energies of 1.12, 2.12, 3.12 and 4.12 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Vansola, Vibha [M.S. Univ., Baroda (India). Dept. of Physics; Ghosh, Reetuparna; Badwar, Sylvia [North Eastern Hill Univ., Meghalaya (India). Dept. of Physics; and others

    2015-07-01

    The {sup 197}Au(n,γ){sup 198}Au reaction cross-sections at the neutron energies of 1.12, 2.12, 3.12 and 4.12 MeV were determined by using activation and off-line γ-ray spectrometric technique. The mono-energetic neutron energies of 1.12-4.12 MeV were generated from the {sup 7}Li(p,n) reaction by using the proton energies of 3 and 4 MeV from the folded tandem ion beam accelerator (FOTIA) at BARC as well as 5 and 6 MeV from the Pelletron facility at TIFR, Mumbai. The {sup 115}In(n,γ){sup 116m}In reaction cross-section was used as the neutron flux monitor. The {sup 197}Au(n,γ){sup 198}Au reaction cross-section at the neutron energies of 3.12 and 4.12 MeV are reported for the first time. The {sup 197}Au(n,γ){sup 198}Au reaction cross-sections at 1.12 and 2.12 MeV are close to the literature data of in between neutron energies. The {sup 197}Au(n,γ){sup 198}Au cross-section was also calculated theoretically by using the computer code TALYS 1.6 and found to be higher than the experimental data of present work and literature data within the neutron energies of 0.8 to 4 MeV.

  1. Electrocatalytic Activity of Carbonized Nanostructured Polyanilines for Oxidation Reactions: Sensing of Nitrite Ions and Ascorbic Acid

    International Nuclear Information System (INIS)

    Micić, Darko; Šljukić, Biljana; Zujovic, Zoran; Travas-Sejdic, Jadranka; Ćirić-Marjanović, Gordana

    2014-01-01

    Highlights: • Carbonized PANIs prepared from various nanostructured PANI precursors • Electroanalytical performances of carbonized PANIs evaluated using voltammetry • Study of carbonized PANIs physico-chemical properties related to electroactivity • The lowest over-potential for NO 2 − oxidation at c-PANI (+0.87 V vs. SCE) • The lowest over-potential for ascorbic acid oxidation at both c-PANI and c-PANI-SSA - Abstract: A comparative study of the electrocatalytic activity of nitrogen-containing carbon nanomaterials, prepared by the carbonization of nanostructured polyaniline (PANI) salts, for the electrooxidation reactions is presented. Nanostructured PANI salts were synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in an aqueous solution in the presence of 5-sulfosalicylic acid (PANI-SSA), 3,5-dinitrosalicylic acid (PANI-DNSA) as well as without added acid (PANI), and subsequently carbonized to c-PANI-SSA, c-PANI-DNSA and c-PANI, respectively. Glassy carbon tip was modified with nanostructured c-PANIs and used for the investigation of sensing of nitrite and ascorbic acid in aqueous solutions as model analytes by linear sweep voltammetry. All three types of the investigated c-PANIs gave excellent response to the nitrite ions and ascorbic acid electrooxidation. The lowest peak potential for nitrite ion oxidation exhibited c-PANI (+0.87 V vs. SCE), and for ascorbic acid oxidation both c-PANI and c-PANI-SSA (ca. + 0.13 V vs. SCE). Electrochemical data were correlated with structural and textural data obtained by Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, elemental and nitrogen sorption analysis

  2. Mechanisms of alpha emitter production in 12C induced reactions at 1 GeV

    International Nuclear Information System (INIS)

    Dufour, J.P.; Delagrange, H.; Del Moral, R.

    1982-01-01

    We present cross sections, mean projected recoil ranges and angular distributions of radioactive alpha emitters produced in 12 C-induced reactions at 1 GeV on targets ranging from Gd to Pb. We use a new technique of on-line electrostatic collection. The wide spectrum of produced isotopes corresponds to nuclei close to the target up to nuclei with as much as 60 nucleons less than the target. The intranuclear cascade calculations can reproduce the main features of nuclei having lost up

  3. Reaction dynamics of {sup 34-38}Mg projectile with carbon target using Glauber model

    Energy Technology Data Exchange (ETDEWEB)

    Shama, Mahesh K., E-mail: maheshphy82@gmail.com [School of Physics and Material Sciences, Thapar University Patiala-147004 (India); Department of Applied Sciences, Chandigarh Engineering College, Landran Mohali-140307 (India); Panda, R. N. [Department of Physics, ITER, Shiksha O Anusandhan University, Bhubaneswar-751030 (India); Sharma, Manoj K. [School of Physics and Material Sciences, Thapar University Patiala-147004 (India); Patra, S. K. [Institute of Physics, Sachivalaya marg Bhubneswar-751005 (India)

    2015-08-28

    We have studied nuclear reaction cross-sections for {sup 34-38}Mg isotopes as projectile with {sup 12}C target at projectile energy 240AMeV using Glauber model with the conjunction of densities from relativistic mean filed formalism. We found good agreement with the available experimental data. The halo status of {sup 37}Mg is also investigated.

  4. Synthesis and characterization of hydrotalcite-hydroxyapatite material doped with carbon nanotubes and its application in catalysis of transesterification reaction

    International Nuclear Information System (INIS)

    Rodrigues, E.; Barros, T.; Pereira, C.; Almeida, O.; Brasil, H.; Reis, M.A L. dos

    2018-01-01

    The aim of this study was to synthesize and characterize hydrotalcite-hydroxyapatite (HTHAp) material doped with three different proportions (1, 5 and 15% w/w) of carbon nanotubes (NTC) in order to evaluate its potential as a heterogeneous catalyst in the soybean oil methanolysis reaction. The synthesis of the HTHAp material was performed by the co-precipitation method (10≤pH≤ 11) with ultrasonic homogenization and hydrothermal treatment at 80 °C. XRD, SEM/EDS, FT-IR, Raman, N 2 physisorption and TG/DTA were the characterization techniques performed. The sample HTHAp1NTC, doped at 1% w/w, was tested as a catalyst under two temperature conditions (180 and 240 °C), 4 h reaction time, 2.5% catalyst loading and alcohol:oil ratio of 12:1. Doping contributed to improve structural, morphological and thermal stability properties of HTHAp material. The yield results achieved 35.2% (180 °C) and 40.5% (240 °C) qualifying the HTHAp material doped with CNT as a potential catalyst in the transesterification reaction. (author)

  5. RCNP E398 {sup 16}O,{sup 12}C(p,p’) experiment: Measurement of the γ-ray emission probability from giant resonances in relation to {sup 16}O,{sup 12}C(ν,ν’) reactions

    Energy Technology Data Exchange (ETDEWEB)

    Ou, I.; Yamada, Y.; Mori, T.; Yano, T.; Sakuda, M. [Department of Physics, Okayama University, Okayama 700-8530 (Japan); Tamii, A.; Suzuki, T.; Yosoi, M.; Aoi, N.; Ideguchi, E.; Hashimoto, T.; Miki, K.; Ito, T.; Iwamoto, C.; Yamamoto, T. [Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki, Osaka 567-0047 (Japan); Akimune, H. [Department of Physics, Konan University, Okamoto 8-9-1, Higashinada, Kobe 658-8501 (Japan)

    2015-05-15

    We propose to measure the γ-ray emission probability from excited states above 5 MeV including giant resonance of {sup 16}O and {sup 12}C as a function of excitation energy in 1-MeV step. Here, we measure both the excitation energy (E{sub x}=5-30MeV) at the forward scattering angles (0°-3°) of the {sup 16}O, {sup 12}C (p, p’) reaction using Grand-Raiden Spectrometer and the energy of γ-rays (E{sub γ}) using an array of NaI(Tl) counters. The purpose of the experiment is to provide the basic and important information not only for the γ-ray production from primary neutral-current neutrino-oxygen (-carbon) interactions but also for that from the secondary hadronic (neutron-oxygen and -carbon) interactions.

  6. Kinetic Modeling of the Reaction Rate for Quartz and Carbon Black Pellet

    Science.gov (United States)

    Li, Fei; Tangstad, Merete

    2018-06-01

    The kinetic modeling for the carbothermal reduction reaction rate in quartz and carbon black pellets is studied at different temperatures, under varying CO partial pressures in ambient atmosphere, varying carbon contents, different quartz particle sizes, and different crucible opening areas. Carbon black is produced by the cracking of natural gas. The activation energy of the SiC-producing step was determined to be 594 kJ/mol. The averaged pre-exponential factor A obtained from 1898 K, 1923 K, and 1948 K (1625 °C, 1650 °C, and 1675 °C) is 2.62E+16 min-1. The reaction rate of the gas-solid interface factor, fix-C content ( X fix-C), temperature ( T), and CO partial pressure ( X CO) can be expressed as follows: {{d/pct}}{{{d}t}} = (1 - 0.40 × X_{{{fix} - C}}^{ - 0.86} × {pct}) × 2.62 × 10^{16} × \\exp ( { - 594000/RT} ) × (2.6 - 0.015 × X_{co} ).

  7. The reactions of loaded carbon nanotubes, studied by novel electron microscope techniques

    International Nuclear Information System (INIS)

    Rawcliffe, A.

    1999-01-01

    A novel electron microscope technique, controlled environment transmission electron microscopy (CETEM), has been used to investigate the reaction of materials loaded within the internal cavities of carbon nanotubes. CETEM allows the introduction of up to 20 mbar of gas around an electron microscope sample, while maintaining a high resolution imaging capability. The microscope is stable, flexible and reliable under these conditions and high resolution images of encapsulated transmission metal oxide reduction have been recorded at 460 deg. C. Recently discovered carbon nanotubes have in theory many applications, many of which will require controlled reliable loading of the internal cavity. However, at present, there is little experimental evidence to confirm theoretical descriptions of the fundamental mechanisms which govern both the extent of loading and the state in which it is found. Similarly, reaction within the cavity and the effect of encapsulation on the nano-scale particle distribution must also be understood, and CETEM proves to be an ideal technique for the study of these processes. Nanotubes have been loaded from aqueous solution with (NH 4 ) 2 IrCI 6 and with molten MoO 3 or K 2 WO 4 /WO 3 . Bulk samples of the first salt are known to decompose spontaneously in air at 200 deg. C, and the bulk oxides are partially reduced at temperature under hydrogen to give potentially useful conducting phases. Comparing the reaction of these materials it is thus possible to: investigate the effect of loading on their reaction; compare the reaction of these materials in- and out-side the tube cavity; and assess the result of violent loading processes on the tubes themselves. Fortuitously, a spontaneous decomposition, a solid-gas reduction and a phase rearrangement were all recorded, allowing mechanistic implications of encapsulation to be considered for each of these reactions. Perhaps surprisingly, the results can be largely interpreted using the reported bulk

  8. Measurement of the Induced Proton Polarization Pn in the 12C(e, e', p) reaction

    International Nuclear Information System (INIS)

    Woo, R.J.; Barkhuff, David; Bertozzi, William; Jian-ping Chen; Dan Dale; G. Dodson; K.A. Dow; Marty Epstein; Manouchehr Farkhondeh; Mike Finn; Shalev Gilad; Mark K. Jones; Kyungseon Joo; James Kelly; Stanley Kowalski; Bob Lourie; Richard Madey; Dimitri Margaziotis; Pete Markowitz; Justin McIntyre; Christoph Mertz; Brian Milbrath; Joseph Mitchell; Charles F. Perdrisat; Vina Punjabi; Paul Rutt; Adam Sarty; D. Tieger; C. Tschalaer; William Turchinetz; Paul E. Ulmer; S.P. Van Verst; C. Vellidis; Glen Warren; Lawrence Weinstein

    1998-01-01

    The first measurements of the induced proton polarization Pn for the 12C(e,e',p) reaction are reported. The experiment was performed at quasifree kinematics for energy and momentum transfer (w,q) = (294 MeV, 765 MeV/c) and sampled a missing momentum range of 0-250 MeV/c. The induced polarization arises from final-state interactions and for these kinematics is dominated by the real part of the spin-orbit optical potential. The distorted-wave impulse approximation provides good agreement with data for the 1 p3/2 shell. The data for the continuum suggest that both the 1s1/2 shell and underlying l > 1 configurations contribute

  9. Supercritical carbon dioxide versus toluene as reaction media in silica functionalisation: Synthesis and characterisation of bonded aminopropyl silica intermediate.

    Science.gov (United States)

    Ashu-Arrah, Benjamin A; Glennon, Jeremy D

    2017-06-09

    This research reports supercritical carbon dioxide versus toluene as reaction media in silica functionalisation for use in liquid chromatography. Bonded aminopropyl silica (APS) intermediates were prepared when porous silica particles (Exsil-pure, 3μm) were reacted with 3-aminopropyltriethoxysilane (3-APTES) or N,N-dimethylaminopropyltrimethoxysilane (DMAPTMS) using supercritical carbon dioxide (sc-CO 2 ) and toluene as reaction media. Covalent bonding to silica was confirmed using elemental microanalysis (CHN), thermogravimetric analysis (TGA), zeta potential (ξ), diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, scanning electron microscopy (SEM) and solid-state nuclear magnetic resonance (CP/MAS NMR) spectroscopy. The results demonstrate that under sc-CO 2 conditions of 100°C/414bar in a substantial reduced time of 3h, the surface coverage of APS (evaluated from%C obtained from elemental analysis) prepared with APTES (%C: 8.03, 5.26μmol/m -2 ) or DMAPTES (%C: 5.12, 4.58μmol/m 2 ) is somewhat higher when compared to organic based reactions under reflux in toluene at a temperature of 110°C in 24h with APTES (%C: 7.33, 4.71μmol/m 2 ) and DMAPTMS (%C: 4.93, 4.38μmol/m 2 ). Zeta potential measurements revealed a change in electrostatic surface charge from negative values for bare Exsil-pure silica to positive for functionalised APS materials indicating successful immobilization of the aminosilane onto the surface of silica. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Coating of graphite flakes with MgO/carbon nanocomposite via gas state reaction

    Energy Technology Data Exchange (ETDEWEB)

    Sharif, M., E-mail: Sharif_m@metaleng.iust.ac.i [Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Faghihi-Sani, M.A. [Sharif University of Technology, Tehran (Iran, Islamic Republic of); Golestani-Fard, F. [Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Saberi, A. [Tabriz University (Iran, Islamic Republic of); Soltani, Ali Khalife [Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)

    2010-06-18

    Coating of graphite flakes with MgO/carbon nanocomposite was carried out via gaseous state reaction between mixture of Mg metal, CO gas and graphite flakes at 1000 {sup o}C. XRD and FE-SEM analysis of coating showed that the coating was comprised of MgO nano particles and amorphous carbon distributed smoothly and covered the graphite surface evenly. Thermodynamic calculations were employed to predict the reaction sequences as well as phase stability. The effect of coating on water wettability and oxidation resistance of graphite was studied using contact angle measurement and TG analysis, respectively. It was demonstrated that the reaction between Mg and CO could result in MgO/C nanocomposite deposition. The coating improved water wettability of graphite and also enhanced the oxidation resistance of graphite flakes significantly. Also the graphite coating showed significant phenolic resin-wettabilty owing to high surface area of such hydrophilic nano composite coating. The importance of graphite coating is explained with emphasis on its potential application in graphite containing refractories.

  11. Coating of graphite flakes with MgO/carbon nanocomposite via gas state reaction

    International Nuclear Information System (INIS)

    Sharif, M.; Faghihi-Sani, M.A.; Golestani-Fard, F.; Saberi, A.; Soltani, Ali Khalife

    2010-01-01

    Coating of graphite flakes with MgO/carbon nanocomposite was carried out via gaseous state reaction between mixture of Mg metal, CO gas and graphite flakes at 1000 o C. XRD and FE-SEM analysis of coating showed that the coating was comprised of MgO nano particles and amorphous carbon distributed smoothly and covered the graphite surface evenly. Thermodynamic calculations were employed to predict the reaction sequences as well as phase stability. The effect of coating on water wettability and oxidation resistance of graphite was studied using contact angle measurement and TG analysis, respectively. It was demonstrated that the reaction between Mg and CO could result in MgO/C nanocomposite deposition. The coating improved water wettability of graphite and also enhanced the oxidation resistance of graphite flakes significantly. Also the graphite coating showed significant phenolic resin-wettabilty owing to high surface area of such hydrophilic nano composite coating. The importance of graphite coating is explained with emphasis on its potential application in graphite containing refractories.

  12. The Carbonation of Wollastonite: A Model Reaction to Test Natural and Biomimetic Catalysts for Enhanced CO2 Sequestration

    Directory of Open Access Journals (Sweden)

    Fulvio Di Lorenzo

    2018-05-01

    Full Text Available One of the most promising strategies for the safe and permanent disposal of anthropogenic CO2 is its conversion into carbonate minerals via the carbonation of calcium and magnesium silicates. However, the mechanism of such a reaction is not well constrained, and its slow kinetics is a handicap for the implementation of silicate mineral carbonation as an effective method for CO2 capture and storage (CCS. Here, we studied the different steps of wollastonite (CaSiO3 carbonation (silicate dissolution → carbonate precipitation as a model CCS system for the screening of natural and biomimetic catalysts for this reaction. Tested catalysts included carbonic anhydrase (CA, a natural enzyme that catalyzes the reversible hydration of CO2(aq, and biomimetic metal-organic frameworks (MOFs. Our results show that dissolution is the rate-limiting step for wollastonite carbonation. The overall reaction progresses anisotropically along different [hkl] directions via a pseudomorphic interface-coupled dissolution–precipitation mechanism, leading to partial passivation via secondary surface precipitation of amorphous silica and calcite, which in both cases is anisotropic (i.e., (hkl-specific. CA accelerates the final carbonate precipitation step but hinders the overall carbonation of wollastonite. Remarkably, one of the tested Zr-based MOFs accelerates the dissolution of the silicate. The use of MOFs for enhanced silicate dissolution alone or in combination with other natural or biomimetic catalysts for accelerated carbonation could represent a potentially effective strategy for enhanced mineral CCS.

  13. Mechanism of ({sup 14}N, {sup 12}B) reactions at intermediate energy leading to large spin-polarization of {sup 12}B

    Energy Technology Data Exchange (ETDEWEB)

    Mitsuoka, Shin-ichi [Osaka Univ., Ibaraki (Japan). Research Center for Nuclear Physics; Shimoda, Tadashi; Miyatake, Hiroari [and others

    1996-05-01

    To study mechanisms of the ({sup 14}N, {sup 12}B) reactions at intermediate energies, double differential cross section and nuclear spin-polarization of the {sup 12}B projectile-like fragments have been measured as a function of longitudinal momentum in the angular range of 0deg - 9deg. Large spin-polarization of the reaction products {sup 12}B has been observed in the {sup 9}Be({sup 14}N, {sup 12}B) reaction at 39.3 MeV/u. The momentum distributions at forward angles exhibit characteristic features which can not be understood by the current projectile fragmentation picture. It is shown that by assuming the existence of direct two-proton transfer process in addition to the fragmentation process, both the cross section and polarization of {sup 12}B fragments are successfully explained. The target and incident energy dependence of the momentum distribution are also explained reasonably. (author)

  14. Effects of doping in 25-atom bimetallic nanocluster catalysts for carbon–carbon coupling reaction of iodoanisole and phenylacetylene

    Directory of Open Access Journals (Sweden)

    Zhimin Li

    2016-10-01

    Full Text Available We here report the catalytic effects of foreign atoms (Cu, Ag, and Pt doped into well-defined 25-gold-atom nanoclusters. Using the carbon-carbon coupling reaction of p-iodoanisole and phenylacetylene as a model reaction, the gold-based bimetallic MxAu25−x(SR18 (–SR=–SCH2CH2Ph nanoclusters (supported on titania were found to exhibit distinct effects on the conversion of p-iodoanisole as well as the selectivity for the Sonogashira cross-coupling product, 1-methoxy-4-(2-phenylethynylbenzene. Compared to Au25(SR18, the centrally doped Pt1Au24(SR18 causes a drop in catalytic activity but with the selectivity retained, while the AgxAu25−x(SR18 nanoclusters gave an overall performance comparable to Au25(SR18. Interestingly, CuxAu25−x(SR18 nanoclusters prefer the Ullmann homo-coupling pathway and give rise to product 4,4′-dimethoxy-1,1′-biphenyl, which is in opposite to the other three nanocluster catalysts. Our overall conclusion is that the conversion of p-iodoanisole is largely affected by the electronic effect in the bimetallic nanoclusters’ 13-atom core (i.e., Pt1Au12, CuxAu13−x, and Au13, with the exception of Ag doping, and that the selectivity is primarily determined by the type of atoms on the MxAu12−x shell (M=Ag, Cu, and Au in the nanocluster catalysts.

  15. Observation of non-statistical structures in the excitation function of the reaction 10B(14N,12C)12C under extreme forward angles

    International Nuclear Information System (INIS)

    Klauss, E.U.

    1984-01-01

    In the present thesis the excitation functions of the reaction 10 B( 14 N, 12 C) 12 C to the ground states, the first excited state at 4.43 MeV (Jsup(π) = 2 1 + ) of a 12 C residual nucleus, and to the double excitation of ejectile and residue nucleus to the 4.43 state are studied. The measurements were performed in an energy range 13MeV 14 N) 0 (in the c.m. system). By a fitting to elastic scattering data the optical potential for 10 B+ 14 N was determined. With this potential it was tried by means of Hauser-Feshbach calculations to calculate the cross sections of the reaction 10 B( 14 N, 12 C) 12 C. The strong 16 + resonance and indications of 18 + in the excitation function of the reaction 10 B( 14 N, 12 Csub(g.s.)) 12 Csub(g.s.) should be pronounced. An unexpected large cross section was observed in the reaction 10 B( 14 N, 12 Csub(g.s.)) 12 C(4 1 + ). This is considered as a further indication to the strong contribution of a direct process. (orig./HSI) [de

  16. Mace-like hierarchical MoS2/NiCo2S4 composites supported by carbon fiber paper: An efficient electrocatalyst for the hydrogen evolution reaction

    Science.gov (United States)

    Sun, Lan; Wang, Tao; Zhang, Long; Sun, Yunjin; Xu, Kewei; Dai, Zhengfei; Ma, Fei

    2018-02-01

    The rational design and preparation of earth-abundant, stable and efficient electrocatalysts for hydrogen production is currently the subject in extensive scientific and technological researches toward the future of a clean-energy society. Herein, a mace-like MoS2/NiCo2S4 hierarchical structure is designed and synthesized on carbon fiber paper via a facile hydrothermal method, and evaluated as electrocatalyst for hydrogen evolution reaction. In the MoS2/NiCo2S4/carbon fiber paper hierarchical structures, MoS2 nanosheets are dispersively distributed on the surface of NiCo2S4 nanowires, which provides an enlarged surface area, abundant interfaces and catalytic active sites. As for hydrogen evolution reaction, such MoS2/NiCo2S4/carbon fiber paper heterostructures give rise to a hydrogen evolution reaction catalytic current density of 10 mA cm-2 with a lower overpotential of 139 mV and a smaller Tafel slope of 37 mV·dec-1 than those of MoS2/carbon fiber paper and NiCo2S4/carbon fiber paper counterparts, exhibiting a prominent electrocatalytic performance. Moreover, the electrocatalytic properties change little after 5000 CV cycles and continual electrolysis for 12 h without obvious decay, respectively, demonstrating high durability and stability. The excellent hydrogen evolution reaction performances endow the hierarchical configuration MoS2/NiCo2S4/carbon fiber paper with promising alternative in HER and other related renewable energy fields.

  17. Preparation of ultra-fine calcium carbonate by a solvent-free reaction using supersonic airflow and low temperatures

    OpenAIRE

    Cai, Yan-Hua; Ma, Dong-Mei; Peng, Ru-Fang; Chu, Shi-Jin

    2008-01-01

    The treatment of calcium chloride with sodium carbonate under solvent-free conditions with a supersonic airflow and at a low heating temperature leads to the synthesis of ultra-fine calcium carbonate. The reaction not only involves mild conditions, a simple operation, and high yields but also gives a high conversion rate.

  18. Quasi-bound alpha resonant states populated by the 12C(6Li, d) reaction

    International Nuclear Information System (INIS)

    Rodrigues, M.R.D.; Borello-Lewin, T.; Miyake, H.; Horodynski-Matsushigue, L.B.; Duarte, J.L.M.; Rodrigues, C.L.; Souza, M.A.; Cunsolo, A.; Cappuzzello, F.; Foti, A.; Agodi, C.; Cavallaro, M.; Ukita, G.M.

    2012-01-01

    Full text: The alpha cluster phenomenon in the light nuclei structure has been the subject of a long time investigation since the proposal of the Ikeda diagrams [1]. The main purpose of the research program in progress is the investigation of this phenomenon in (xα) and (xα+n) nuclei through the ( 6 Li, d) alpha transfer reaction [2-4]. Alpha resonant states around the (4α) threshold in the nucleus 16 O are the focus of the present contribution. In fact, the importance of these resonances at the elements production in stars is recognized, as primarily pointed out by Hoyle in 12 C [6]. The existence of a rotational band with the α + 12 C (Hoyle) cluster state structure was recently demonstrated by Ohkubo and Hirabayashi [6]. In order to explore this region of interest, measurements of the 12 C( 6 Li, d) 16 O reaction up to 17 MeV of excitation at an incident energy of 25.5 MeV, have been performed employing the Sao Paulo Pelletron-Enge Split-Pole facility and the nuclear emulsion detection technique (plates Fuji G6B, 50 μm thick). Spectra associated with six scattering angles, from 5 deg to 29 deg in the laboratory frame, each one 50 cm along the focal surface, were measured. Several narrow resonances with a quasi-bound behavior embedded in the continuum were detected and the resolution of 25 keV allowed for the separation of doublets not resolved before [7,8]. The absolute cross sections and the respective deuteron angular distributions were determined and the analysis is in progress. [1] K. Ikeda et al., Prog. Theor. Phys. Suppl. E 68, 464 (1968); H. Horiuchi, K. Ikeda, and Y. Suzuki, ibid. 44, 225 (1978). [2] M.R.D.Rodrigues et al., in12th International Conference on Nuclear Reaction Mechanism, Varenna, Italy, edited by F. Cerutti and A. Ferrari , CERN Proceedings, 2010-2, pp. 331- 335. [3] T. Borello-Lewin et al., Proceedings of SOTANCP2, Brussels, Belgium 2010, edited by P. Descouvemount et al., Int. J. Mod. Mod. Phys E 20, 1018-1021 (2011). [4] T. Borello

  19. Dilepton spectroscopy at intermediate energies; the carbon - carbon reaction at 1 GeV/A; Spectroscopie des dileptons aux energies intermediaires; la reaction carbone - carbone A 1 GeV/A

    Energy Technology Data Exchange (ETDEWEB)

    Prunet, M

    1995-06-01

    The Physics context of this work is heavy ion collisions at relativistic energies where di-electron provide informations on the produced hot and dense nuclear matter. The experiment is performed by the DiLepton Spectrometer (DLS) Collaboration at the Lawrence Berkeley`s Bevalac. After a description of the apparatus, we review the whole program and the main results so far obtained: first evidence of a significant di-electron signal at energies above 1 GeV/A; improvement of the understanding of di-electron production (electromagnetic decays of hadrons, {pi}{sup +}{pi}{sup -} annihilation and hadronic Bremsstrahlung). The results of p-p, p-d reactions from 1 to 4.9 GeV/A show that hadronic Bremsstrahlung (pp, pn) should be reformulated. Our analysis, optimized on the reaction Carbon-Carbon at 1 GeV/A, has been applied to {alpha}-Ca and d-Ca. We have developed two main aspects: improvement of the time resolution (500 ps) in order to eliminate all of the protons. Improvement of the space resolution (300 {mu}) for better mass resolution, in particular in the {rho} region. We obtain the cross section of di-electron production as a function of mass, transverse momentum and rapidity from the C-C, {alpha}-Ca and d-Ca reactions at 1 GeV/A. We also compare the cross section for all of the measured systems at 1 GeV/A, including Ca-Ca, and we show a (ApAt){sup {alpha}} dependence with {alpha} {approx_equal} 1.1. A study of the associated multiplicity has also been performed. Nevertheless, the limited acceptance of the DLS and its poor mass resolution to identify the {rho}, {omega} vector mesons, do not allow to conclude on hadron behaviour in nuclear matter. This point is one of the main goal of the HADES project at GSI (Darmstadt), which we give a brief description of the main features. (authors). 60 refs.

  20. Carbon-14 immobilization via the CO2-Ba(OH)2 hydrate gas-solid reaction

    International Nuclear Information System (INIS)

    Haag, G.L.

    1980-01-01

    Although no restrictions have been placed on the release of carbon-14, it has been identified as a potential health hazard due to the ease in which it may be assimilated into the biosphere. The intent of the Carbon-14 Immobilization Program, funded through the Airborne Waste Program Management Office, is to develop and demonstrate a novel process for restricting off-gas releases of carbon-14 from various nuclear facilities. The process utilizes the CO 2 -Ba(OH) 2 hydrate gas-solid reaction to directly remove and immobilize carbon-14. The reaction product, BaCO 3 , possesses both the thermal and chemical stability desired for long-term waste disposal. The process is capable of providing decontamination factors in excess of 1000 and reactant utilization of greater than 99% in the treatment of high volumetric, airlike (330 ppM CO 2 ) gas streams. For the treatment of an air-based off-gas stream, the use of packed beds of Ba(OH) 2 .8H 2 O flakes to remove CO 2 has been demonstrated. However, the operating conditions must be maintained between certain upper and lower limits with respect to the partial pressure of water. If the water vapor pressure in the gas is less than the dissociation vapor pressure of Ba(OH) 2 .8H 2 O, the bed will deactivate. If the vapor pressure is considerably greater, pressure drop problems will increase with increasing humidity as the particles curl and degrade. Results have indicated that when operated in the proper regime, the bulk of the increase in pressure drop results from the conversion of Ba(OH) 2 .8H 2 O to BaCO 3 and not from the hydration of the commercial Ba(OH) 2 .8H 2 O (i.e. Ba(OH) 2 .7.50H 2 O) to Ba(OH) 2 .8H 2 O

  1. Hetero-atom doped carbon nanotubes for dye degradation and oxygen reduction reaction

    Energy Technology Data Exchange (ETDEWEB)

    Nandan, Ravi, E-mail: aerawat27@gmail.com; Nanda, Karuna Kar [Materials Research Centre, Indian Institute of Science, Bangalore-560012 (India)

    2015-06-24

    We report the synthesis of nitrogen doped vertically aligned multi-walled (MWNCNTs) carbon nanotubes by pyrolysis and its catalytic performance for degradation of methylene blue (MB) dye & oxygen reduction reaction (ORR). The degradation of MB was monitored spectrophotometrically with time. Kinetic studies show the degradation of MB follows a first order kinetic with rate constant k=0.0178 min{sup −1}. The present rate constant is better than that reported for various supported/non-supported semiconducting nanomaterials. Further ORR performance in alkaline media makes MWNCNTs a promising cost-effective, fuel crossover tolerance, metal-free, eco-friendly cathode catalyst for direct alcohol fuel cell.

  2. Numerical study for melting heat transfer and homogeneous-heterogeneous reactions in flow involving carbon nanotubes

    Science.gov (United States)

    Hayat, Tasawar; Muhammad, Khursheed; Alsaedi, Ahmed; Asghar, Saleem

    2018-03-01

    Present work concentrates on melting heat transfer in three-dimensional flow of nanofluid over an impermeable stretchable surface. Analysis is made in presence of porous medium and homogeneous-heterogeneous reactions. Single and multi-wall CNTs (carbon nanotubes) are considered. Water is chosen as basefluid. Adequate transformations yield the non-linear ordinary differential systems. Solution of emerging problems is obtained using shooting method. Impacts of influential variables on velocity and temperature are discussed graphically. Skin friction coefficient and Nusselt number are numerically discussed. The results for MWCNTs and SWCNTs are compared and examined.

  3. Metal-phthalocyanine functionalized carbon nanotubes as catalyst for the oxygen reduction reaction: A theoretical study

    Science.gov (United States)

    Orellana, Walter

    2012-07-01

    The covalent functionalization of metallic single-walled carbon nanotubes (CNTs) with transition metal phthalocyanines (MPc, with M = Mn, Fe and Co) are addressed by density functional calculations. The CNT-MPc catalytic activity toward the oxygen reduction reaction (ORR) is investigated through the O2 stretching frequency adsorbed on the phthalocyanine metal center. We find better reduction abilities when the CNT functionalization occurs through sp2-like bonds. Multiple stable-spin states for the M-O2 adduct are also found for M = Mn and Fe, suggesting higher ORR rates. The CNT-MPc complexes show metallic characteristics, suggesting favorable conditions to work as ORR cathode catalysts in fuel cells.

  4. Electrocatalytic performance of Pu(IV)/Pu(III) redox reaction at graphene modified glassy carbon electrode

    International Nuclear Information System (INIS)

    Gupta, Ruma; Gamare, J.S.; Kamat, J.V.; Aggarwal, S.K.

    2014-01-01

    In this paper we explore the analytical perspectives of graphene modified electrode utilising commercially available graphene, which is well characterised, completely free from surfactants and has not been purposely oxidised or treated. We compare and critically contrast the electro-analytical performance of graphene modified glassy carbon electrodes (Gr/GC) with that of unmodified GC electrode towards Pu(IV)/Pu(III) redox reaction, monitoring of which has considerable importance in a plethora of areas where electrochemistry is conveniently and beneficially utilised for determination of nuclear fuels

  5. Palladium on Carbon-Catalyzed Suzuki-Miyaura Coupling Reaction Using an Efficient and Continuous Flow System

    Directory of Open Access Journals (Sweden)

    Tomohiro Hattori

    2015-01-01

    Full Text Available The continuous flow Suzuki-Miyaura reaction between various haloarenes and arylboronic acids was successfully achieved within only ca. 20 s during the single-pass through a cartridge filled with palladium on carbon (Pd/C. No palladium leaching was observed in the collected reaction solution by atomic absorption spectrometry (detection limit: 1 ppm.

  6. Measurement of the 115In(n,γ)116 m In reaction cross-section at the neutron energies of 1.12, 2.12, 3.12 and 4.12 MeV

    Science.gov (United States)

    Lawriniang, Bioletty Mary; Badwar, Sylvia; Ghosh, Reetuparna; Jyrwa, Betylda; Vansola, Vibha; Naik, Haladhara; Goswami, Ashok; Naik, Yeshwant; Datrik, Chandra Shekhar; Gupta, Amit Kumar; Singh, Vijay Pal; Pol, Sudir Shibaji; Subramanyam, Nagaraju Balabenkata; Agarwal, Arun; Singh, Pitambar

    2015-08-01

    The 115In(n,γ)116 m In reaction cross section at neutron energies of 1.12, 2.12, 3.12 and 4.12 MeV was determined by using an activation and off-line γ-ray spectrometric technique. The monoenergetic neutron energies of 1.12 - 4.12 MeV were generated from the 7Li(p,n) reaction by using proton beam with energies of 3 and 4 MeV from the folded tandem ion beam accelerator (FOTIA) at Bhabha Atomic Research Centre (BARC) and with energies of 5 and 6 MeV from the Pelletron facility at Tata Institute of Fundamental Research (TIFR), Mumbai. The 197Au(n,γ)198Au reaction cross-section was used as the neutron flux monitor.The 115In(n,γ)116 m In reaction cross section at neutron energies of 1.12, 2.12, 3.12 and 4.12 MeV was determined by using an activation and off-line γ-ray spectrometric technique. The monoenergetic neutron energies of 1.12 - 4.12 MeV were generated from the 7Li(p,n) reaction by using proton beam with energies of 3 and 4 MeV from the folded tandem ion beam accelerator (FOTIA) at Bhabha Atomic Research Centre (BARC) and with energies of 5 and 6 MeV from the Pelletron facility at Tata Institute of Fundamental Research (TIFR), Mumbai. The 197Au(n,γ)198 Au reaction cross-section was used as the neutron flux monitor. The 115In(n,γ)116 m In reaction cross-sections at neutron energies of 1.12 - 4.12 MeV were compared with the literature data and were found to be in good agreement with one set of data, but not with others. The 115In(n,γ)116 m In cross-section was also calculated theoretically by using the computer code TALYS 1.6 and was found to be slightly lower than the experimental data from the present work and the literature.)198Au reaction cross-section was used as the neutron flux monitor. The 115In(n,γ)116 m In reaction cross-sections at neutron energies of 1.12 - 4.12 MeV were compared with the literature data and were found to be in good agreement with one set of data, but not with others. The 115In(n,γ)116 m In cross-section was also calculated

  7. Evaluating the Catalytic Effects of Carbon Materials on the Photocatalytic Reduction and Oxidation Reactions of TiO2

    International Nuclear Information System (INIS)

    Khan, Gulzar; Kim, Young Kwang; Choi, Sung Kyu; Han, Dong Suk; Abdelwahab, Ahmed; Park, Hyunwoong

    2013-01-01

    TiO 2 composites with seven different carbon materials (activated carbons, graphite, carbon fibers, single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene oxides, and reduced graphene oxides) that are virgin or treated with nitric acid are prepared through an evaporation method. The photocatalytic activities of the as-prepared samples are evaluated in terms of H 2 production from aqueous methanol solution (photo-catalytic reduction: PCR) and degradation of aqueous pollutants (phenol, methylene blue, and rhodamine B) (photocatalytic oxidation: PCO) under AM 1.5-light irradiation. Despite varying effects depending on the kinds of carbon materials and their surface treatment, composites typically show enhanced PCR activity with maximum 50 times higher H 2 production as compared to bare TiO 2 . Conversely, the carbon-induced synergy effects on PCO activities are insignificant for all three substrates. Colorimetric quantification of hydroxyl radicals supports the absence of carbon effects. However, platinum deposition on the binary composites displays the enhanced effect on both PCR and PCO reactions. These differing effects of carbon materials on PCR and PCO reactions of TiO 2 are discussed in terms of physicochemical properties of carbon materials, coupling states of TiO 2 /carbon composites, interfacial charge transfers. Various surface characterizations of composites (UV-Vis diffuse reflectance, SEM, FTIR, surface area, electrical conductivity, and photoluminescence) are performed to gain insight on their photocatalytic redox behaviors

  8. Production of carbon nanotubes using mechanical milling in the presence of an exothermic reaction

    International Nuclear Information System (INIS)

    Karimi, E.Z.; Zebarjad, S.M.; Khaki, J. Vahdati; Izadi, H.

    2010-01-01

    Carbon nanotubes (CNTs) have shown promising potential for many applications in field of engineering due to their unusual significant properties. A major challenge for the industrial applications of CNTs is the large-quantity production. In this field, one new method for CNT production is annealing the ball milled graphite powder. The annealing process should be done in high temperature (1200-1400 o C) and needs time more than 6 h. The novel process introduced in this paper is elimination the annealing stage thorough a thermite reaction. The necessity heat for the conversion of milling products to CNTs was generated in the milling chamber by an exothermic reaction. In addition, the reaction products acted as catalysts to the CNT formation process. The adiabatic temperatures of 1809, 2000 and 2325 K were selected according to balancing graphite and thermite mixture (Aluminum + Iron oxide powders) for exothermic reaction. The results of thermo gravimetric analysis (TGA) test proved that CNT formation strongly depends on adiabatic temperature. The results of microscopic evaluation done by transition electron microscope (TEM) showed that at higher adiabatic temperature CNTs could be produced.

  9. Integral measurement of the {sup 12}C(n, p){sup 12}B reaction up to 10 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Zugec, P.; Bosnar, D. [University of Zagreb, Department of Physics, Faculty of Science, Zagreb (Croatia); Colonna, N.; Barbagallo, M.; Mastromarco, M.; Tagliente, G.; Variale, V. [Istituto Nazionale di Fisica Nucleare, Bari (Italy); Ventura, A. [Istituto Nazionale di Fisica Nucleare, Bologna (Italy); Mengoni, A. [ENEA, Bologna (Italy); Altstadt, S.; Langer, C.; Lederer, C.; Reifarth, R.; Schmidt, S.; Weigand, M. [Johann-Wolfgang-Goethe Universitaet, Frankfurt (Germany); Andrzejewski, J.; Marganiec, J.; Perkowski, J. [Uniwersytet Lodzki, Lodz (Poland); Audouin, L.; Leong, L.S.; Tassan-Got, L. [Centre National de la Recherche Scientifique/IN2P3 - IPN, Orsay (France); Becares, V.; Cano-Ott, D.; Garcia, A.R.; Gonzalez-Romero, E.; Martinez, T.; Mendoza, E. [Centro de Investigaciones Energeticas Medioambientales y Tecnologicas (CIEMAT), Madrid (Spain); Becvar, F.; Krticka, M.; Kroll, J.; Valenta, S. [Charles University, Prague (Czech Republic); Belloni, F.; Mondalaers, W.; Plompen, A.; Schillebeeckx, P. [European Commission JRC, Institute for Reference Materials and Measurements, Geel (Belgium); Berthoumieux, E.; Fraval, K.; Gunsing, F. [CEA/Saclay - IRFU, Gif-sur-Yvette (France); Billowes, J.; Ware, T.; Wright, T. [University of Manchester, Manchester (United Kingdom); Boccone, V.; Brugger, M.; Calviani, M.; Cerutti, F.; Chiaveri, E.; Chin, M.; Ferrari, A.; Guerrero, C.; Losito, R.; Roman, F.; Rubbia, C.; Tsinganis, A.; Versaci, R.; Vlachoudis, V.; Weiss, C. [CERN, Geneva (Switzerland); Calvino, F.; Cortes, G.; Gomez-Hornillos, M.B.; Riego, A. [Universitat Politecnica de Catalunya, Barcelona (Spain); Carrapico, C.; Goncalves, I.F.; Sarmento, R.; Vaz, P. [Universidade de Lisboa, C2TN-Instituto Superior Tecnico, Lisboa (Portugal); Cortes-Giraldo, M.A.; Praena, J.; Quesada, J. [Universidad de Sevilla, Sevilla (Spain); Cosentino, L.; Finocchiaro, P. [INFN - Laboratori Nazionali del Sud, Catania (Italy); Diakaki, M.; Karadimos, D.; Kokkoris, M.; Vlastou, R. [National Technical University of Athens (NTUA), Athens (Greece); Domingo-Pardo, C.; Giubrone, G.; Tain, J.L. [CSIC-Universidad de Valencia, Instituto de Fisica Corpuscular, Valencia (Spain); Dressler, R.; Heinitz, S.; Kivel, N.; Schumann, D. [Paul Scherrer Institut, Villigen (Switzerland); Duran, I.; Tarrio, D. [Universidade de Santiago de Compostela, Santiago de Compostela (Spain); Eleftheriadis, C.; Manousos, A. [Aristotle University of Thessaloniki, Thessaloniki (Greece); Ganesan, S.; Gurusamy, P.; Saxena, A. [Bhabha Atomic Research Centre (BARC), Mumbai (India); Griesmayer, E.; Jericha, E.; Leeb, H. [Atominstitut der Oesterreichischen Universitaeten, Technische Universitaet Wien, Wien (Austria); Jenkins, D.G.; Vermeulen, M.J. [University of York, York, Heslington (United Kingdom); Kaeppeler, F. [Karlsruhe Institute of Technology (KIT), Institut fuer Kernphysik, Karlsruhe (Germany); Lo Meo, S. [Istituto Nazionale di Fisica Nucleare, Bologna (Italy); ENEA, Bologna (Italy); Massimi, C.; Mingrone, F.; Vannini, G. [Dipartimento di Fisica, Universita di Bologna (IT); INFN, Bologna (IT); Mastinu, P. [Laboratori Nazionali di Legnaro, Istituto Nazionale di Fisica Nucleare, Legnaro (IT); Milazzo, P.M. [Istituto Nazionale di Fisica Nucleare, Trieste (IT); Mirea, M. [Horia Hulubei National Institute of Physics and Nuclear Engineering - IFIN HH, Magurele (RO); Musumarra, A. [Universita di Catania, Dipartimento di Fisica e Astronomia DFA, Catania (IT); INFN-Laboratori Nazionali del Sud, Catania (IT); Paradela, C. [European Commission JRC, Institute for Reference Materials and Measurements, Geel (BE); Universidade de Santiago de Compostela, Santiago de Compostela (ES); Pavlik, A. [Faculty of Physics, University of Vienna, Wien (AT); Rauscher, T. [University of Hertfordshire, Centre for Astrophysics Research, School of Physics, Astronomy and Mathematics, Hatfield (GB); University of Basel, Department of Physics, Basel (CH); Wallner, A. [Faculty of Physics, University of Vienna, Wien (AT); Australian National University, Research School of Physics and Engineering, Canberra (AU)

    2016-04-15

    The integral measurement of the {sup 12}C(n, p){sup 12}B reaction was performed at the neutron time-of-flight facility nTOF at CERN. The total number of {sup 12}B nuclei produced per neutron pulse of the nTOF beam was determined using the activation technique in combination with a time-of-flight technique. The cross section is integrated over the nTOF neutron energy spectrum from reaction threshold at 13.6 MeV to 10 GeV. Having been measured up to 1GeV on basis of the {sup 235}U(n, f) reaction, the neutron energy spectrum above 200 MeV has been re-evaluated due to the recent extension of the cross section reference for this particular reaction, which is otherwise considered a standard up to 200 MeV. The results from the dedicated GEANT4 simulations have been used to evaluate the neutron flux from 1 GeV up to 10 GeV. The experimental results related to the {sup 12}C(n, p){sup 12}B reaction are compared with the evaluated cross sections from major libraries and with the predictions of different GEANT4 models, which mostly underestimate the {sup 12}B production. On the contrary, a good reproduction of the integral cross section derived from measurements is obtained with TALYS-1.6 calculations, with optimized parameters. (orig.)

  10. Efficient Construction of Energetic Materials via Nonmetallic Catalytic Carbon-Carbon Cleavage/Oxime-Release-Coupling Reactions.

    Science.gov (United States)

    Zhao, Gang; He, Chunlin; Yin, Ping; Imler, Gregory H; Parrish, Damon A; Shreeve, Jean'ne M

    2018-03-14

    The exploitation of C-C activation to facilitate chemical reactions is well-known in organic chemistry. Traditional strategies in homogeneous media rely upon catalyst-activated or metal-mediated C-C bonds leading to the design of new processes for applications in organic chemistry. However, activation of a C-C bond, compared with C-H bond activation, is a more challenging process and an underdeveloped area because thermodynamics does not favor insertion into a C-C bond in solution. Carbon-carbon bond cleavage through loss of an oxime moiety has not been reported. In this paper, a new observation of self-coupling via C-C bond cleavage with concomitant loss of oxime in the absence of metals (either metal-complex mediation or catalysis) results in dihydroxylammonium 5,5-bistetrazole-1,10-diolate (TKX-50) as well as N, N'-([3,3'-bi(1,2,4-oxadiazole)]-5,5'-diyl)dinitramine, a potential candidate for a new generation of energetic materials.

  11. The nuclear reaction analysis (NRA) as a means for detecting carbon in GaAs and in source materials and additives

    International Nuclear Information System (INIS)

    Bethge, K.; Mader, A.; Michelmann, R.; Krauskopf, J.; Thee, P.; Meyer, J.D.

    1991-01-01

    The nuclear reaction ananlysis (NRA) on the basis of the reaction 12 C (d,p) 13 C is a method allowing the detection and description of both lateral and depth profiles of the presence of carbon in GaAs and in the source materials and additives. The NRA is an absolute method with a detection limit for C of approx. 4x10 15 cm 3 . The achievable detection range in depth under the experimental conditions goes from the surface down to 6 μm. Combined with channeling measurements, NRA is capable of identifying the position of carbon in the GaAs crystal lattice, and thus permits to examine the mobility of C in GaAs. (BBR) With 11 refs [de

  12. Effect of Carbon Coating on Li4TiO12 of Anode Material for Hybrid Capacitor.

    Science.gov (United States)

    Lee, Jong-Kyu; Lee, Byung-Gwan; Yoon, Jung-Rag

    2015-11-01

    The carbon-coated Li4Ti5O12 of anode material for hybrid capacitor was prepared by controlling carbonization time at 700 degrees C in nitrogen. With increasing of carbonization time, the discharge capacity and capacitance were decreased, while the equivalent series resistance was not changed remarkably. The rate capability and cycle performance of carbon-coated Li4Ti5O12 were larger than that of Li4Ti5O12. Carbon coating improved conductivity as well as Li-ion diffusion, and thus also resulted in good rate capabilities and cycle stability. The effects of carbon coating on the gas generation of hybrid capacitor were also discussed.

  13. Postural reactions of girls and boys aged 12–15 years evaluated using the Romberg test

    Directory of Open Access Journals (Sweden)

    Jacek Wilczyński

    2016-07-01

    Full Text Available Introduction : The complex system controlling human posture includes a gaze stabilisation system, which comprises the control of direction and visual acuity during head and body movements, and a posture stabilisation system, keeping the body in balance at rest and in movement. Aim of the research: To analyse the postural reaction of SOX and SOY using the Romberg test with eyes open (EO and closed (CE in girls and boys aged 12–15 years. Material and methods : The study included 503 students of Primary School No. 13 and School No. 4 in Starachowice. Postural reactions were tested on a Cosmogamma platform by Emildue R50300. Postural reactions were analysed, and mean sway X (MSX and mean sway Y (MSY were calculated. Results: Analysis of variance showed significant differences of MSX only between girls and boys (p < 0.036. MSX was significantly lower in girls in both tests with EO and CE. Although there was no apparent significant difference of MSX between the Romberg test with EO and CE, a slight progression was observed in the test with CE. Analysis of variance of MSY with a single classification showed a significant effect of study options (p < 0.048, a significant interaction of gender and options of the study (p < 0.048, and a significant interaction of age and options of the study (p < 0.026. Analysis of variance of MSY showed a significant progression of MSY in the test with CE. Conclusions : Our research showed that balance with CE does not worsen, so it can be assumed that children have limited skills of using vision to maintain balance because there is a lack of appropriate coordination between vision and motor abilities, which in children are in development.

  14. Electro-deposition of Pd on Carbon paper and Ni foam via surface limited redox-replacement reaction for oxygen reduction reaction

    International Nuclear Information System (INIS)

    Modibedi, Remegia M.; Mathe, Mkhulu K.; Motsoeneng, Rapelang G.; Khotseng, Lindiwe E.; Ozoemena, Kenneth I.; Louw, Eldah K.

    2014-01-01

    Pd nanostructured catalysts were electrodeposited by surface-limited redox replacement reactions using the electrochemical atomic layer deposition technique. Carbon paper and Ni foam were used as substrates for the electrodeposition of the metal. Supported nanostructured Pd electrodes were characterized using electrochemical methods and scanning electron microscopy. Carbon paper and Ni foam produced good quality deposits with some agglomeration on Ni foam. The EDX profiles confirmed the presence of Pd particles. Cyclic voltammograms of the electrodeposited Pd on substrates showed features characteristic of polycrystalline Pd electrodes. In the acidic electrolyte a very weak oxygen reduction reaction (ORR) activity was observed on Pd/Carbon paper electrode when compared to Pd/Ni foam electrode. The Pd/Ni foam electrode showed improved ORR activity in alkaline medium

  15. Reaction mechanism for the symmetric breakup of 24Mg following an interaction with 12C

    International Nuclear Information System (INIS)

    Gyapong, G.J.; Watson, D.L.; Catford, W.N.; Clarke, N.M.; Bennett, S.J.; Freer, M.; Fulton, B.R.; Jones, C.D.; Leddy, M.; Murgatroyd, J.T.; Rae, W.D.M.; Simmons, P.

    1994-01-01

    Data on the yield of the symmetric breakup of 24 Mg as a function of beam energy are presented and compared with detailed calculations of the energy dependence. The 24 Mg states seen in symmetric breakup agree with previously observed breakup states having spin and parities J π =4 + ,(6 + ),8 + . The data allow the variations of yield for indivual states to be judged, as the beam energy is varied. The variation in the yield of the 4 + states is compared in detail with calculations assuming several possible compound nuclear or direct reaction mechanisms. It is concluded that a massive ( 12 C) transfer or a simple statistical compound process are unlikely mechanisms, but that each of several other mechanisms is consistent with the data. ((orig.))

  16. 40 CFR 600.510-12 - Calculation of average fuel economy and average carbon-related exhaust emissions.

    Science.gov (United States)

    2010-07-01

    ... and average carbon-related exhaust emissions. 600.510-12 Section 600.510-12 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) ENERGY POLICY FUEL ECONOMY AND CARBON-RELATED EXHAUST EMISSIONS OF... Transportation. (iv) [Reserved] (2) Average carbon-related exhaust emissions will be calculated to the nearest...

  17. Hybrid capacitors utilizing halogen-based redox reactions at interface between carbon positive electrode and aqueous electrolytes

    Science.gov (United States)

    Yamazaki, Shigeaki; Ito, Tatsuya; Murakumo, Yuka; Naitou, Masashi; Shimooka, Toshiharu; Yamagata, Masaki; Ishikawa, Masashi

    2016-09-01

    We propose novel hybrid capacitors (HCs) with electrolyte-involved redox reactions of bromide or iodide species by pretreatment of an activated carbon positive electrode. The treatment is simple; impregnation of pores at an activated carbon fiber cloth (ACFC) as a positive electrode with bromine- or iodine-containing water before cell assembly. The treated positive electrode is applied to a HC cell with a non-treated negative electrode of ACFC and its electrochemical performance is investigated by galvanostatic cycling and leakage current tests. Few studies on such "electrolytic" charge storage systems have provided acceptable capacitor performance because of inevitable self-discharge caused by diffusion of charged species form an electrode to the other one through an electrolyte. Nevertheless, our electrolyte-redox-based HCs show excellent performance without undesirable diffusion of charged species. Moreover, the present HC utilizing a bromide redox system fulfills a practical cell voltage of 1.8 V in spite of an aqueous electrolyte system. This high voltage provides excellent energy density, which is 5 times higher than that in a conventional aqueous electric double-layer capacitor (EDLC), and 1.2 times higher even than that in a 2.7 V-class non-aqueous EDLC, while keeping high charge-discharge rate capability.

  18. Investigation of chemical and electrochemical reactions mechanisms in a direct carbon fuel cell using olive wood charcoal as sustainable fuel

    Science.gov (United States)

    Elleuch, Amal; Halouani, Kamel; Li, Yongdan

    2015-05-01

    Direct carbon fuel cell (DCFC) is a high temperature fuel cell using solid carbon as fuel. The use of environmentally friendly carbon material constitutes a promising option for the DCFC future. In this context, this paper focuses on the use of biomass-derived charcoal renewable fuel. A practical investigation of Tunisian olive wood charcoal (OW-C) in planar DCFCs is conducted and good power density (105 mW cm-2) and higher current density (550 mA cm-2) are obtained at 700 °C. Analytical and predictive techniques are performed to explore the relationships between fuel properties and DCFC chemical and electrochemical mechanisms. High carbon content, carbon-oxygen groups and disordered structure, are the key parameters allowing the achieved good performance. Relatively complex chain reactions are predicted to explain the gas evolution within the anode. CO, H2 and CH4 participation in the anodic reaction is proved.

  19. Geometrical aspects of reaction cross sections for {sup 3}He, {sup 4}He and {sup 12}C projectiles

    Energy Technology Data Exchange (ETDEWEB)

    Ingemarsson, A. [Uppsala Univ. (Sweden). Dept. of Radiation Sciences; Lantz, M. [Uppsala Univ. (Sweden). The Svedberg Laboratory

    2003-04-01

    A black-disc model combined with accurate matter densities has been used for an investigation of reaction cross sections for {sup 3}He, {sup 4}He and {sup 12}C projectiles. A simple relation is derived between the energy dependence of the reaction cross sections and the strength of the nucleon-nucleon interaction. A comparison is also made of the reaction cross sections for {sup 3}He and {sup 4}He for six different nuclei {sup 12}C, {sup 16}O, {sup 40}Ca, {sup 58,60}Ni and {sup 208}Pb.

  20. Triple-element compound-specific stable isotope analysis of 1,2-dichloroethane for characterization of the underlying dehalogenation reaction in two Dehalococcoides mccartyi strains.

    Science.gov (United States)

    Franke, Steffi; Lihl, Christina; Renpenning, Julian; Elsner, Martin; Nijenhuis, Ivonne

    2017-12-01

    Chlorinated ethanes belong to the most common groundwater and soil contaminants. Of these, 1,2-dichloroethane (1,2-DCA) is a man-made, persistent and toxic contaminant, released due to improper waste treatment at versatile production sites. This study investigated the anaerobic transformation of 1,2-DCA by Dehalococcoides mccartyi strain 195 and strain BTF08 using triple-element compound-specific stable isotope analysis of carbon, chlorine and hydrogen for the first time. Isotope fractionation patterns for carbon (εCBTF08 = -28.4 ± 3.7‰; εC195 = -30.9 ± 3.6‰) and chlorine (εClBTF08 = -4.6 ± 0.7‰; εCl195 = -4.2 ± 0.5‰) within both investigated D. mccartyi strains, as well as the dual-element analysis (ΛBTF08 = 6.9 ± 1.2; Λ195 = 7.1 ± 0.2), supported identical reaction mechanisms for dehalogenation of 1,2-DCA. Hydrogen isotope fractionation analysis revealed dihaloelimination as prevalent reaction mechanism. Vinyl chloride as major intermediate could be excluded by performing the experiment in deuterated aqueous media. Furthermore, evaluation of the derived apparent kinetic isotope effects (AKIECBTF08 = 1.029/AKIEC195 = 1.031; AKIEClBTF08 = 1.005/AKIECl195 = 1.004) pointed towards simultaneous abstraction of both involved chlorine-substituents in a concerted matter. It was shown that D. mccartyi strain BTF08 and strain 195 are capable of complete, direct dihaloelimination of 1,2-DCA to ethene. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  1. Construction of Polarized Carbon-Nickel Catalytic Surfaces for Potent, Durable, and Economic Hydrogen Evolution Reactions.

    Science.gov (United States)

    Zhou, Min; Weng, Qunhong; Popov, Zakhar I; Yang, Yijun; Antipina, Liubov Yu; Sorokin, Pavel B; Wang, Xi; Bando, Yoshio; Golberg, Dmitri

    2018-05-22

    Electrocatalytic hydrogen evolution reaction (HER) in alkaline solution is hindered by its sluggish kinetics toward water dissociation. Nickel-based catalysts, as low-cost and effective candidates, show great potentials to replace platinum (Pt)-based materials in the alkaline media. The main challenge regarding this type of catalysts is their relatively poor durability. In this work, we conceive and construct a charge-polarized carbon layer derived from carbon quantum dots (CQDs) on Ni 3 N nanostructure (Ni 3 N@CQDs) surfaces, which simultaneously exhibit durable and enhanced catalytic activity. The Ni 3 N@CQDs shows an overpotential of 69 mV at a current density of 10 mA cm -2 in a 1 M KOH aqueous solution, lower than that of Pt electrode (116 mV) at the same conditions. Density functional theory (DFT) simulations reveal that Ni 3 N and interfacial oxygen polarize charge distributions between originally equal C-C bonds in CQDs. The partially negatively charged C sites become effective catalytic centers for the key water dissociation step via the formation of new C-H bond (Volmer step) and thus boost the HER activity. Furthermore, the coated carbon is also found to protect interior Ni 3 N from oxidization/hydroxylation and therefore guarantees its durability. This work provides a practical design of robust and durable HER electrocatalysts based on nonprecious metals.

  2. Effect of different chemical modification of carbon nanotubes for the oxygen reduction reaction in alkaline media

    International Nuclear Information System (INIS)

    Dumitru, Anca; Mamlouk, M.; Scott, K.

    2014-01-01

    The electrochemical reduction of oxygen on chemically modified multi-walled carbon nanotubes (CNTs) electrodes in 1 M KOH solution has been studied using the rotating ring disc electrode (RDE). The surface modification of CNTs has been estimated by XPS and Raman spectroscopy. The effect of different oxygen functionalities on the surface of carbon nanotube for the oxygen reduction reaction (ORR) is considered in terms of the number of electrons (n) involved. Electrochemical studies indicate that in the case of the modification of CNTs with citric acid and diazonium salts the n values were close to two in the measured potential range, and the electrochemical reduction is limited to the production of peroxide as the final product. In the case of the modification of carbon nanotubes with peroxymonosulphuric acid, in the measured potential range, the n value is close to 4 indicating the four-electron pathway for the ORR. By correlating ORR measurements with the XPS analysis, we propose that the increase in electrocatalytic activity towards the ORR, for CNT can be attributed to the increase in C-O groups on the surface of CNTs after modification with peroxymonosulphuric acid

  3. Ordered hierarchically porous carbon codoped with iron and nitrogen as electrocatalyst for the oxygen reduction reaction.

    Science.gov (United States)

    Deng, Chengwei; Zhong, Hexiang; Yao, Lan; Liu, Sisi; Xu, Zhuang; Zhang, Huamin

    2014-12-01

    N-doped carbon catalysts have attracted great attention as potential alternatives to expensive Pt-based catalysts used in fuel cells. Herein, an ordered hierarchically porous carbon codoped with N and Fe (Fe-NOHPC) is prepared by an evaporation-induced self-assembly process followed by carbonization under ammonia. The soft template and Fe species promote the formation of the porous structure and facilitate the oxygen reduction reaction (ORR).The catalyst possesses an ordered hierarchically porous structure with a large surface area (1172.5 m(2) g(-1) ) and pore volume of 1.03 cm(3) g(-1) . Compared to commercial 20% Pt/C, it exhibits better ORR catalytic activity and higher stability as well as higher methanol tolerance in an alkaline electrolyte, which demonstrates its potential use in fuel cells as a nonprecious cathode catalyst. The N configuration, Fe species, and pore structure of the catalysts are believed to correlate with its high catalytic activity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Production of hydrogen through the carbonation-calcination reaction applied to CH4/CO2 mixtures

    International Nuclear Information System (INIS)

    Barelli, L.; Bidini, G.; Corradetti, A.; Desideri, U.

    2007-01-01

    The production of hydrogen combined with carbon capture represents a possible option for reducing CO 2 emissions in atmosphere and anthropogenic greenhouse effect. Nowadays the worldwide hydrogen production is based mainly on natural gas reforming, but the attention of the scientific community is focused also on other gas mixtures with significant methane content. In particular mixtures constituted mainly by methane and carbon dioxide are extensively used in energy conversion applications, as they include land-fill gas, digester gas and natural gas. The present paper addresses the development of an innovative system for hydrogen production and CO 2 capture starting from these mixtures. The plant is based on steam methane reforming, coupled with the carbonation and calcination reactions for CO 2 absorption and desorption, respectively. A thermodynamic approach is proposed to investigate the plant performance in relation to the CH 4 content in the feeding gas. The results suggest that, in order to optimize the hydrogen purity and the efficiency, two different methodologies can be adopted involving both the system layout and operating parameters. In particular such methodologies are suitable for a methane content, respectively, higher and lower than 65%

  5. Anaerobic reductive dechlorination of tetrachloroethene: how can dual Carbon-Chlorine isotopic measurements help elucidating the underlying reaction mechanism?

    Science.gov (United States)

    Badin, Alice; Buttet, Géraldine; Maillard, Julien; Holliger, Christof; Hunkeler, Daniel

    2014-05-01

    to catalyse PCE reductive dechlorination according to a different mechanism. In another study, an m value of 2.5±0.8 was found for PCE anaerobic dechlorination by a bacterial consortium dominated by species closely related to Desulfitobacterium aromaticivorans strain UKTL (consortia A) [2]. This value is indistinguishable from the one found for PceATCE within a 95% confidence interval although the reductive dehalogenase protein sequence of consortia A is distinctly different from the sequences of our two cultures. This suggests that the reaction mechanism is not related to the similarities between reductive dehalogenases. References 1. Abe, Y., et al., Carbon and Chlorine Isotope Fractionation during Aerobic Oxidation and Reductive Dechlorination of Vinyl Chloride and cis-1,2-Dichloroethene. Environmental Science & Technology, 2009. 43(1): p. 101-107. 2. Wiegert, C., et al., Carbon and Chlorine Isotope Fractionation During Microbial Degradation of Tetra- and Trichloroethene. Environmental Science & Technology, 2013. 47(12): p. 6449-6456.

  6. Coprecipitation of {sup 14}C and Sr with carbonate precipitates: The importance of reaction kinetics and recrystallization pathways

    Energy Technology Data Exchange (ETDEWEB)

    Hodkin, David J. [School of Earth and Environment, University of Leeds, Leeds LS2 9JT (United Kingdom); Stewart, Douglas I. [School of Civil Engineering, University of Leeds (United Kingdom); Graham, James T. [National Nuclear Laboratory, Sellafield, Cumbria (United Kingdom); Burke, Ian T., E-mail: I.T.Burke@leeds.ac.uk [School of Earth and Environment, University of Leeds, Leeds LS2 9JT (United Kingdom)

    2016-08-15

    This study investigated the simultaneous removal of Sr{sup 2+} and {sup 14}CO{sub 3}{sup 2−} from pH > 12 Ca(OH){sub 2} solution by the precipitation of calcium carbonate. Initial Ca{sup 2+}:CO{sub 3}{sup 2−} ratios ranged from 10:1 to 10:100 (mM:mM). Maximum removal of {sup 14}C and Sr{sup 2+} both occurred in the system containing 10 mM Ca{sup 2+} and 1 mM CO{sub 3}{sup 2−} (99.7% and 98.6% removal respectively). A kinetic model is provided that describes {sup 14}C and Sr removal in terms of mineral dissolution and precipitation reactions. The removal of {sup 14}C was achieved during the depletion of the initial TIC in solution, and was subsequently significantly affected by recrystallization of the calcite precipitate from an elongate to isotropic morphology. This liberated > 46% of the {sup 14}C back to solution. Sr{sup 2+} removal occurred as Ca{sup 2+} became depleted in solution and was not significantly affected by the recrystallization process. The proposed reaction could form the basis for low cost remediation scheme for {sup 90}Sr and {sup 14}C in radioactively contaminated waters (<$0.25 reagent cost per m{sup 3} treated). - Highlights: • 99.7% of {sup 14}C and 98.6% of Sr removed from aqueous solution by CaCO{sub 3} precipitation. • Remobilization of {sup 14}C observed during calcium carbonate recrystallization. • Sr displayed variable distribution coefficient (possibly affected by Ca:Sr ratio). • Reagent cost of $0.22/m{sup 3} of treated groundwater.

  7. Nitrogen and Fluorine-Codoped Carbon Nanowire Aerogels as Metal-Free Electrocatalysts for Oxygen Reduction Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Shaofang [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 USA; Zhu, Chengzhou [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 USA; Song, Junhua [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 USA; Engelhard, Mark H. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99352 USA; Xiao, Biwei [Energy and Environmental Directory, Pacific Northwest National Laboratory, Richland WA 99352 USA; Du, Dan [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 USA; Lin, Yuehe [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 USA

    2017-07-11

    The development of active, durable, and low-cost catalysts to replace noble metal-based materials is highly desirable to promote the sluggish oxygen reduction reaction in fuel cells. Herein, nitrogen and fluorine-codoped three-dimensional carbon nanowire aerogels, composed of interconnected carbon nanowires, were synthesized for the first time by a hydrothermal carbonization process. Owing to their porous nanostructures and heteroatom-doping, the as-prepared carbon nanowire aerogels, with optimized composition, present excellent electrocatalytic activity that is comparable to commercial Pt/C. Remarkably, the aerogels also exhibit superior stability and methanol tolerance. This synthesis procedure paves a new way to design novel heteroatomdoped catalysts.

  8. Energy transfer and reaction dynamics of matrix-isolated 1,2-difluoroethane-d4

    Science.gov (United States)

    Raff, Lionel M.

    1990-09-01

    The molecular dynamics of vibrationally excited 1,2-difluoroethane-d4 isolated in Ar, Kr, and Xe matrices at 12 K are investigated using trajectory methods. The matrix model is an fcc crystal containing 125 unit cells with 666 atoms in a cubic (5×5×5) arrangement. It is assumed that 1,2-difluoroethane-d4 is held interstitially within the volume bounded by the innermost unit cell of the crystal. The transport effects of the bulk are simulated using the velocity reset method introduced by Riley, Coltrin, and Diestler [J. Chem. Phys. 88, 5934 (1988)]. The system potential is written as the separable sum of a lattice potential, a lattice-molecule interaction and a gas-phase potential for 1,2-difluoroethane. The first two of these are assumed to have pairwise form while the molecular potential is a modified form of the global potential previously developed for 1,2-difluoroethane [J. Phys. Chem. 91, 3266 (1987)]. Calculated sublimation energies for the pure crystals are in good accord with the experimental data. The distribution of metastable-state energies for matrix-isolated 1,2-difluoroethane-d4 is Gaussian in form. In krypton, the full width at half maximum for the distribution is 0.37 eV. For a total excitation energy of 6.314 eV, the observed dynamic processes are vibrational relaxation, orientational exchange, and four-center DF elimination reactions. The first of these processes is characterized by a near linear, first-order decay curve with rate coefficients in the range 1.30-1.48×1011 s-1. The average rates in krypton and xenon are nearly equal. The process is slightly slower in argon. The decay curves exhibit characteristic high-frequency oscillations that are generally seen in energy transfer studies. It is demonstrated that these oscillations are associated with the frequencies for intramolecular energy transfer so that the entire frequency spectrum for such transfer processes can be obtained from the Fourier transform of the decay curve. Orientational

  9. Effect of Reaction Temperature on Carbon Yield and Morphology of CNTs on Copper Loaded Nickel Nanoparticles

    Directory of Open Access Journals (Sweden)

    Hu Ming

    2016-01-01

    Full Text Available This investigation was attempted to introduce carbon nanotubes (CNTs onto surface of copper powders in order to improve heat transfer performance of copper matrix for engineering application of electrical packaging materials. The Ni/MgO catalyst was formed on the copper powders surface by means of codeposition method. CVD technique was executed to fabricate uniform CNTs on copper powders and effect of reaction temperature on the morphology of CNTs was surveyed. The results showed that CNTs products on the copper powder surface were distributed uniformly even if reaction temperature was different. The diameter dimension of CNTs was within the scope of 30~60 nm. Growth behaviors of CNTs by CVD method were considered to be “tip-growth” mechanism. Raman spectra of CNTs proved that intensity ratio of D-band to G-band (ID/IG increased as deposition reaction temperature increased, which implied that order degree of graphitic structure in synthesized CNTs improved.

  10. The influenced of reaction time on the degradation of palm oil empty fruit bunch (EFB) in hydrothermal carbonization

    Science.gov (United States)

    Sarwono, Rakhman; Kurniawan, Hendris Hendarsyah

    2017-11-01

    Hydrothermal carbonization (HTC) of empty fruit bunch (EFB) of palm oil in different reaction times were investigated. Experiments were carried out in an autoclave at different reaction time of 3,6,9, 15, 20, 25 and 40 hours. With a fixed solid/liquid ratio of 5 gram of EFB in 50 ml water as a solvent, and temperature reaction of 250 °C. Increase the reaction time the soluble products are also increased. The liquid products were analyzed using GCMS to determine the chemical composition. The chemical composition were greatly affected by the reaction time. The main component was glycolic acid, by increasing the reaction time made the varieties of chemical compositions in liquid products, especially for the glycolic acid component, it was decreased slightly. The higher heating value (HHV) also increase slighly by increasing the reaction time both solid and liquid products.

  11. Non-statistical effects in bond fission reactions of 1,2-difluoroethane

    Science.gov (United States)

    Schranz, Harold W.; Raff, Lionel M.; Thompson, Donald L.

    1991-08-01

    A microcanonical, classical variational transition-state theory based on the use of the efficient microcanonical sampling (EMS) procedure is applied to simple bond fission in 1,2-difluoroethane. Comparison is made with results of trajectory calculations performed on the same global potential-energy surface. Agreement between the statistical theory and trajectory results for CC CF and CH bond fissions is poor with differences as large as a factor of 125. Most importantly, at the lower energy studied, 6.0 eV, the statistical calculations predict considerably slower rates than those computed from trajectories. We conclude from these results that the statistical assumptions inherent in the transition-state theory method are not valid for 1,2-difluoroethane in spite of the fact that the total intramolecular energy transfer rate out of CH and CC normal and local modes is large relative to the bond fission rates. The IVR rate is not globally rapid and the trajectories do not access all of the energetically available phase space uniformly on the timescale of the reactions.

  12. Carboxyl functionalization of carbon fibers via aryl diazonium reaction in molten urea to enhance interfacial shear strength

    International Nuclear Information System (INIS)

    Wang, Yuwei; Meng, Linghui; Fan, Liquan; Wu, Guangshun; Ma, Lichun; Zhao, Min; Huang, Yudong

    2016-01-01

    Graphical abstract: - Highlights: • Carbon fibers are functionalized with benzoic acid groups via aryl diazonium reaction. • Interfacial shear strength of the carbon fibers increases by 66%. • Tensile strength of the carbon fibers is preserved after grafting reaction. • The treatment in molten urea can improve modification efficiency greatly. • Using molten urea as the reaction medium can avoid pollution from organic solvents. - Abstract: Using molten urea as the solvent, carbon fibers were functionalized with carboxylic acid groups via aryl diazonium reaction in 15 min to improve their interfacial bonding with epoxy resin. The surface functionalization was quantified by X-ray photoelectron spectroscopy, which showed that the relative surface coverage of carboxylic acid groups increased from an initial percentage of 3.17–10.41%. Mechanical property test results indicated that the aryl diazonium reaction in this paper could improve the interfacial shear strength by 66%. Meanwhile, the technique did not adopt any pre-oxidation step to produce functional groups prior to grafting and was shown to maintain the tensile strength of the fibers. This methodology provided a rapid, facile and economically viable route to produce covalently functionalized carbon fibers in large quantities with an eco-friendly method.

  13. Carboxyl functionalization of carbon fibers via aryl diazonium reaction in molten urea to enhance interfacial shear strength

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yuwei [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); Meng, Linghui [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Fan, Liquan [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); Wu, Guangshun; Ma, Lichun; Zhao, Min [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Huang, Yudong, E-mail: ydhuang.hit1@yahoo.com.cn [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China)

    2016-01-30

    Graphical abstract: - Highlights: • Carbon fibers are functionalized with benzoic acid groups via aryl diazonium reaction. • Interfacial shear strength of the carbon fibers increases by 66%. • Tensile strength of the carbon fibers is preserved after grafting reaction. • The treatment in molten urea can improve modification efficiency greatly. • Using molten urea as the reaction medium can avoid pollution from organic solvents. - Abstract: Using molten urea as the solvent, carbon fibers were functionalized with carboxylic acid groups via aryl diazonium reaction in 15 min to improve their interfacial bonding with epoxy resin. The surface functionalization was quantified by X-ray photoelectron spectroscopy, which showed that the relative surface coverage of carboxylic acid groups increased from an initial percentage of 3.17–10.41%. Mechanical property test results indicated that the aryl diazonium reaction in this paper could improve the interfacial shear strength by 66%. Meanwhile, the technique did not adopt any pre-oxidation step to produce functional groups prior to grafting and was shown to maintain the tensile strength of the fibers. This methodology provided a rapid, facile and economically viable route to produce covalently functionalized carbon fibers in large quantities with an eco-friendly method.

  14. Final Report: The Impact of Carbonate on Surface Protonation, Electron Transfer and Crystallization Reactions in Iron Oxide Nanoparticles and Colloids

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, David Adams [The University of Alabama

    2013-07-02

    This project addresses key issues of importance in the geochemical behavior of iron oxides and in the geochemical cycling of carbon and iron. For Fe, we are specifically studying the influence of carbonate on electron transfer reactions, solid phase transformations, and the binding of carbonate to reactive sites on the edges of particles. The emphasis on carbonate arises because it is widely present in the natural environment, is known to bind strongly to oxide surfaces, is reactive on the time scales of interest, and has a speciation driven by acid-base reactions. The geochemical behavior of carbonate strongly influences global climate change and CO{sub 2} sequestration technologies. Our goal is to answer key questions with regards to specific site binding, electron transfer reactions, and crystallization reactions of iron oxides that impact both the geochemical cycling of iron and CO{sub 2} species. Our work is focused on the molecular level description of carbonate chemistry in solution including the prediction of isotope fractionation factors. We have also done work on critical atmospheric species.

  15. Reaction

    African Journals Online (AJOL)

    abp

    19 oct. 2017 ... Reaction to Mohamed Said Nakhli et al. concerning the article: "When the axillary block remains the only alternative in a 5 year old child". .... Bertini L1, Savoia G, De Nicola A, Ivani G, Gravino E, Albani A et al ... 2010;7(2):101-.

  16. Analysis of the 12C (e,e'pd) Reaction at High Energy Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Neil [Univ. of Glasgow, Scotland (United Kingdom)

    2011-03-31

    The Jefferson Lab Hall A experiment E01015 measured the differential cross sections of the 12C (e,e'pd) reaction with low yields for kinematics of w = 0.865 GeV , Q2 = 2 (GeV/c)2, xB = 1.2 at three kinematic settings of 12C (e,e'p) missing momentum of 300, 400 and 500 MeV/c. The main objective of the experiment was to measure the 12C (e, e0p) cross section and the cross section ratios of 12C (e,e'pp) and 12C (e,e'pn) to investigate Short Range Correlations. The 12C (e,e'pd) reaction was investigated to find out what its magnitude of cross section. The very low yields and differential cross sections of 12C (e,e'pd) reaction measured at the three different kinematic settings suggests that the contribution of many of the different reaction mechanisms, including three nucleon forces, may be suppressed at the kinematics of this experiment.

  17. Localized surface grafting reactions on carbon nanofibers induced by gamma and e-beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Evora, M.C., E-mail: cecilia@ieav.cta.br [Institute for Advanced Studies-IEAV/DCTA, Av. Cel Jose Alberto Albano do Amarante, 1-Putim, 12228-001 São Jose dos Campos, SP (Brazil); Araujo, J.R., E-mail: jraraujo@inmetro.gov.br [Instituto Nacional de Metrologia, Qualidade e Tecnologia, Av. Nossa Sra. das Graças, 50, 25250-020 Duque de Caxias, RJ (Brazil); Ferreira, E.H.M. [Instituto Nacional de Metrologia, Qualidade e Tecnologia, Av. Nossa Sra. das Graças, 50, 25250-020 Duque de Caxias, RJ (Brazil); Strohmeier, B.R. [Thermo Fisher Scientific, 5225 Verona Road, Madison, WI 53711 (United States); Silva, L.G.A., E-mail: lgasilva@ipen.br [Institute for Nuclear and Energy Research- IPEN, Av. Prof lineu Prestes, 2242- Cidade Universitaria, 05508-000 SP (Brazil); Achete, C.A. [Instituto Nacional de Metrologia, Qualidade e Tecnologia, Av. Nossa Sra. das Graças, 50, 25250-020 Duque de Caxias, RJ (Brazil)

    2015-04-30

    Graphical abstract: - Highlights: • Methodology for the functionalization of carbon nanofibers was investigated. • Two radiation sources were used to promote grafting reactions: gamma and electron beam. • We report the optimum inhibitor concentration to achieve the functionalization. • Surface of carbon nanofibers showed an increase of oxygen content after irradiation. • The radiation-induced graphitization did not damage the overall sp{sup 2} structure. - Abstract: Electron beam and gamma-ray irradiation have potential application to modify the carbon fiber nanostructures in order to produce useful defects in the graphitic structure and create reactive sites. In this study, the methodology to functionalize carbon nanofiber (CNF), via a radiation process and using acrylic acid as a source of oxygen functional groups, was investigated. The samples were submitted to a direct grafting radiation process with electron beam and gamma-ray source. Several parameters were changed such as: acrylic acid concentration, radiation dose and percentage of inhibitor necessary to achieve functionalization, with higher percentage of oxygen functional groups on CNF surface, and better dispersion. The better results achieved were when mixing CNF in a solution of acrylic acid with 6% of inhibitor (FeSO{sub 4}·7H{sub 2}O) and irradiated at 100 kGy. The samples were characterized by X-ray photoelectron spectroscopy and the surface composition (atomic%) showed a significant increase of oxygen content for the samples after irradiation. Also, the dispersion of the functionalized CNF in water was stable during months which may be a good indication that the functionalization process of CNF via ionizing radiation was successful.

  18. Localized surface grafting reactions on carbon nanofibers induced by gamma and e-beam irradiation

    International Nuclear Information System (INIS)

    Evora, M.C.; Araujo, J.R.; Ferreira, E.H.M.; Strohmeier, B.R.; Silva, L.G.A.; Achete, C.A.

    2015-01-01

    Graphical abstract: - Highlights: • Methodology for the functionalization of carbon nanofibers was investigated. • Two radiation sources were used to promote grafting reactions: gamma and electron beam. • We report the optimum inhibitor concentration to achieve the functionalization. • Surface of carbon nanofibers showed an increase of oxygen content after irradiation. • The radiation-induced graphitization did not damage the overall sp 2 structure. - Abstract: Electron beam and gamma-ray irradiation have potential application to modify the carbon fiber nanostructures in order to produce useful defects in the graphitic structure and create reactive sites. In this study, the methodology to functionalize carbon nanofiber (CNF), via a radiation process and using acrylic acid as a source of oxygen functional groups, was investigated. The samples were submitted to a direct grafting radiation process with electron beam and gamma-ray source. Several parameters were changed such as: acrylic acid concentration, radiation dose and percentage of inhibitor necessary to achieve functionalization, with higher percentage of oxygen functional groups on CNF surface, and better dispersion. The better results achieved were when mixing CNF in a solution of acrylic acid with 6% of inhibitor (FeSO 4 ·7H 2 O) and irradiated at 100 kGy. The samples were characterized by X-ray photoelectron spectroscopy and the surface composition (atomic%) showed a significant increase of oxygen content for the samples after irradiation. Also, the dispersion of the functionalized CNF in water was stable during months which may be a good indication that the functionalization process of CNF via ionizing radiation was successful

  19. Weak transitions in the quasi-elastic reaction 12C(e,e'p)11B

    International Nuclear Information System (INIS)

    Steenhoven, G. van der; Blok, H.P.; Vrije Univ., Amsterdam; Jans, E.; Lapikas, L.; Quint, E.N.M.; Witt Huberts, P.K.A. de

    1988-01-01

    In a high-resolution quasi-elastic 12 C(e,e'p) 11 B experiment several weak transitions have been observed to excited final states with spin and parity characteristic of direct knockout from orbitals above the 1p shell. The momentum distributions, which have been measured in parallel kinematics at an outgoing-proton energy of 70 MeV in the range of missing momentum - 170 ≤ p m ≤ 210 MeV/c, show the shape expected for a single-step knockout process. It is demonstrated that the interference between a direct-knockout process and a two-step process leading to the same final state in the (e,e'p) reaction may cause important modifications of the deduced spectroscopic factors. Explicit coupled-channels (CC) calculations show that the spectroscopic factor for the transition to the 7 - /2 state at 6.743 MeV is reduced by a factor of 6, whereas the spectroscopic factors of the other weak transitions observed in the present experiment are uncertain by a factor of 2 due to CC-effects. Since the strength of these transitions is larger than can be explained by a pure two-step process, we interpret the observation of these transitions as direct evidence for the existence of ground-state correlations in 12 C. The total spectroscopic strength in the E x region between 6 and 12 MeV amounts to 0.1, or 4.1% of the observed strength for 1p knockout in the low E x region. Two peaks have been identified in the missing-energy spectrum that hitherto have not been reported: A narrow peak at E x =9.82 (3) MeV with an l=0 character and a broad structure centered at about 11.5 MeV with an l=1 character. The missing-energy spectrum between E x =12 and 24 MeV corresponding to 1s 1/2 knockout has also been analyzed. The deduced momentum distribution shows evidence for the onset of a two-nucleon mechanism beyond the two-particle emission threshold. (orig.)

  20. Intermediate- and high-energy reactions of uranium with neon and carbon

    International Nuclear Information System (INIS)

    McGaughey, P.L.

    1982-11-01

    Target fragment production from the interactions of 1.0, 3.0, 4.8, and 12 GeV 12 C and 5.0, 8.0, 20, and 42 GeV 20 Ne with uranium has been measured using off-line gamma-ray spectroscopic techniques. The experimental charge and mass yield distributions are generally consistent with the concepts of limiting fragmentation and factorization at energies of 3.0 GeV and above. The total projectile kinetic energy was found to be the relevant scaling parameter for the comparison of reactions induced by projectiles of different sizes. Light fragments with mass number less than 60 were found to violate limiting fragmentation, and had excitation functions that were strongly increasing with projectile energy until 8.0 to 12.0 GeV. With the 1.0 GeV 12 C beam the pattern of mass yields was quite different from that of all the other reactions, with the normal peak in the fission mass region (80 < A < 145), but with much lower yields below mass number 60 and between mass numbers 145 and 210, indicating that these fragments are formed primarily in very energetic reactions in which large excitation energies are transferred to and significant amounts of mass are removed from the target nucleus. Theoretical predictions of the intra-nuclear cascade, nuclear fireball, and nuclear firestreak models are compared with the experimental results. The intra-nuclear cascade and nuclear firestreak models are both able to predict the general shapes of the experimental distributions, with the exception of the yields for the lightest fragments

  1. Up-Scaling Geochemical Reaction Rates for Carbon Dioxide (CO2) in Deep Saline Aquifers

    Energy Technology Data Exchange (ETDEWEB)

    Peters, Catherine A

    2013-02-28

    Geochemical reactions in deep subsurface environments are complicated by the consolidated nature and mineralogical complexity of sedimentary rocks. Understanding the kinetics of these reactions is critical to our ability to make long-term predictions about subsurface processes such as pH buffering, alteration in rock structure, permeability changes, and formation of secondary precipitates. In this project, we used a combination of experiments and numerical simulation to bridge the gap between our knowledge of these reactions at the lab scale and rates that are meaningful for modeling reactive transport at core scales. The focus is on acid-driven mineral dissolution, which is specifically relevant in the context of CO2-water-rock interactions in geological sequestration of carbon dioxide. The project led to major findings in three areas. First, we modeled reactive transport in pore-network systems to investigate scaling effects in geochemical reaction rates. We found significant scaling effects when CO2 concentrations are high and reaction rates are fast. These findings indicate that the increased acidity associated with geological sequestration can generate conditions for which proper scaling tools are yet to be developed. Second, we used mathematical modeling to investigate the extent to which SO2, if co-injected with CO2, would acidify formation brines. We found that there exist realistic conditions in which the impact on brine acidity will be limited due to diffusion rate-limited SO2 dissolution from the CO2 phase, and the subsequent pH shift may also be limited by the lack of availability of oxidants to produce sulfuric acid. Third, for three Viking sandstones (Alberta sedimentary basin, Canada), we employed backscattered electron microscopy and energy dispersive X-ray spectroscopy to statistically characterize mineral contact with pore space. We determined that for reactive minerals in sedimentary consolidated rocks, abundance alone is not a good predictor of

  2. BOREAS TGB-12 Soil Carbon and Flux Data of NSA-MSA in Raster Format

    Science.gov (United States)

    Hall, Forrest G. (Editor); Knapp, David E. (Editor); Rapalee, Gloria; Davidson, Eric; Harden, Jennifer W.; Trumbore, Susan E.; Veldhuis, Hugo

    2000-01-01

    The BOREAS TGB-12 team made measurements of soil carbon inventories, carbon concentration in soil gases, and rates of soil respiration at several sites. This data set provides: (1) estimates of soil carbon stocks by horizon based on soil survey data and analyses of data from individual soil profiles; (2) estimates of soil carbon fluxes based on stocks, fire history, drain-age, and soil carbon inputs and decomposition constants based on field work using radiocarbon analyses; (3) fire history data estimating age ranges of time since last fire; and (4) a raster image and an associated soils table file from which area-weighted maps of soil carbon and fluxes and fire history may be generated. This data set was created from raster files, soil polygon data files, and detailed lab analysis of soils data that were received from Dr. Hugo Veldhuis, who did the original mapping in the field during 1994. Also used were soils data from Susan Trumbore and Jennifer Harden (BOREAS TGB-12). The binary raster file covers a 733-km 2 area within the NSA-MSA.

  3. Fluid phase equilibria of the reaction mixture during the selective hydrogenation of 2-butenal in dense carbon dioxide

    DEFF Research Database (Denmark)

    Musko, Nikolai; Jensen, Anker Degn; Baiker, Alfons

    2012-01-01

    Knowledge of the phase behaviour and composition is of paramount importance for understanding multiphase reactions. We have investigated the effect of the phase behaviour in the palladium-catalysed selective hydrogenation of 2-butenal to saturated butanal in dense carbon dioxide. The reactions were...... cell. The results of the catalytic experiments showed that small amounts of carbon dioxide added to the system significantly decrease the conversion, whereas at higher loadings of CO2 the reaction rate gradually increases reaching a maximum. The CPA calculations revealed that this maximum is achieved...... performed using a 5wt% Pd on activated carbon in custom-designed high pressure autoclaves at 323K. The Cubic-Plus-Association (CPA) equation of state was employed to model the phase behaviour of the experimentally studied systems. CPA binary interaction parameters were estimated based on the experimental...

  4. Melting Heat in Radiative Flow of Carbon Nanotubes with Homogeneous-Heterogeneous Reactions

    Science.gov (United States)

    Hayat, Tasawar; Muhammad, Khursheed; Muhammad, Taseer; Alsaedi, Ahmed

    2018-04-01

    The present article provides mathematical modeling for melting heat and thermal radiation in stagnation-point flow of carbon nanotubes towards a nonlinear stretchable surface of variable thickness. The process of homogeneous-heterogeneous reactions is considered. Diffusion coefficients are considered equal for both reactant and autocatalyst. Water and gasoline oil are taken as base fluids. The conversion of partial differential system to ordinary differential system is done by suitable transformations. Optimal homotopy technique is employed for the solutions development of velocity, temperature, concentration, skin friction and local Nusselt number. Graphical results for various values of pertinent parameters are displayed and discussed. Our results indicate that the skin friction coefficient and local Nusselt number are enhanced for larger values of nanoparticles volume fraction.

  5. Effect of electron injection on defect reactions in irradiated silicon containing boron, carbon, and oxygen

    Science.gov (United States)

    Makarenko, L. F.; Lastovskii, S. B.; Yakushevich, H. S.; Moll, M.; Pintilie, I.

    2018-04-01

    Comparative studies employing Deep Level Transient Spectroscopy and C-V measurements have been performed on recombination-enhanced reactions between defects of interstitial type in boron doped silicon diodes irradiated with alpha-particles. It has been shown that self-interstitial related defects which are immobile even at room temperatures can be activated by very low forward currents at liquid nitrogen temperatures. Their activation is accompanied by the appearance of interstitial carbon atoms. It has been found that at rather high forward current densities which enhance BiOi complex disappearance, a retardation of Ci annealing takes place. Contrary to conventional thermal annealing of the interstitial boron-interstitial oxygen complex, the use of forward current injection helps to recover an essential part of charge carriers removed due to irradiation.

  6. The reaction of lithium metal vapor with single walled carbon nanotubes of large diameters

    Czech Academy of Sciences Publication Activity Database

    Kalbáč, Martin; Kavan, Ladislav; Dunsch, L.

    2009-01-01

    Roč. 246, 11-12 (2009), s. 2428-2431 ISSN 0370-1972 R&D Projects: GA AV ČR IAA400400911; GA AV ČR KAN200100801; GA AV ČR IAA400400804; GA ČR GC203/07/J067; GA MŠk LC510 Institutional research plan: CEZ:AV0Z40400503 Keywords : lithium * single walled carbon nanotubes * Raman spectroscopy Subject RIV: CG - Electrochemistry Impact factor: 1.150, year: 2009

  7. Reaction

    African Journals Online (AJOL)

    raoul

    12 janv. 2012 ... Key words: Métastase, rate, colon, carcinome. Received: 28/12/2011 - Accepted: 09/01/2012 - Published: ... tomodensitométriques au moment du diagnostic du cancer primitif ou lors du suivi radiologique régulier des patients atteints de cancers. Le recours à la TEP-FDG couplée au scanner serait d'un ...

  8. Five-nucleon simultaneous and sequential transfer in the 12C(11B,6Li)17O and 12C(d,7Li)7Be reactions

    International Nuclear Information System (INIS)

    Jarczyk, L.; Kamys, B.; Kistryn, M.; Magiera, A.; Rudy, Z.; Strzal/kowski, A.; Barna, R.; DAmico, V.; De Pasquale, D.; Italiano, A.; Licandro, M.

    1996-01-01

    Measurements of the angular distributions of the 12 C( 11 B, 6 Li) 17 O reaction were performed at three energies of a 11 B beam: 28, 35, and 40 MeV. The results were analyzed in the frame of the exact finite range distorted wave Born approximation of the first and the second order assuming the simultaneous and sequential transfer of the neutron and the α particle. Such an analysis was also performed for previously measured angular distributions of the 12 C(d, 7 Li) 7 Be reaction at E lab = 78 MeV. In both reactions under investigation dominance was found of the simultaneous transfer of the α particle and the nucleon correlated to the 5 He ( 5 Li) cluster in the ground or the first excited state. copyright 1996 The American Physical Society

  9. Gold-Catalyzed Cyclization of Furan-Ynes bearing a Propargyl Carbonate Group: Intramolecular Diels-Alder Reaction with In Situ Generated Allenes.

    Science.gov (United States)

    Sun, Ning; Xie, Xin; Chen, Haoyi; Liu, Yuanhong

    2016-09-26

    Gold-catalyzed cyclization of various furan-ynes with a propargyl carbonate or ester moiety results in the formation of a series of polycyclic aromatic ring systems. The reactions can be rationalized through a tandem gold-catalyzed 3,3-rearrangement of the propargyl carboxylate moiety in furan-yne substrates to form an allenic intermediate, which is followed by an intramolecular Diels-Alder reaction of furan and subsequent ring-opening of the oxa-bridged cycloadduct. It was found that the steric and electronic properties of phosphine ligands on the gold catalyst had a significant impact on the reaction outcome. In the case of 1,5-furan-yne, the cleavage of the oxa-bridge in the cycloadduct with concomitant 1,2-migration of the R(1) group occurs to furnish anthracen-1(2H)-ones bearing a quaternary carbon center. For 1,4-furan-yne, a facile aromatization of the cycloadduct takes place to give 9-oxygenated anthracene derivatives. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Interlaboratory reaction rate program. 12th progress report, November 1976-October 1979

    International Nuclear Information System (INIS)

    Lippincott, E.P.; McElroy, W.N.; Preston, C.C.

    1980-09-01

    The Interlaboratory Reaction Rate UILRR) program is establishing the capability to accurately measure neutron-induced reactions and reaction rates for reactor fuels and materials development programs. The goal for the principal fission reactions, 235 U, 238 U and 239 Pu, is an accuracy to within +- 5% at the 95% confidence level. Accurate measurement of other fission and nonfission reactions is also required, but to a lesser accuracy, between +- 5% and 10% at the 95% confidence level. A secondary program objective is improvement in knowledge of the nuclear parameters involved in the standarization of fuels and materials dosimetry measurements of neutron flux, spectra, fluence and burnup

  11. Oxygen reduction reaction on carbon-supported CoSe2 nanoparticles in an acidic medium

    International Nuclear Information System (INIS)

    Feng Yongjun; He Ting; Alonso-Vante, Nicolas

    2009-01-01

    We investigated the effect of CoSe 2 /C nanoparticle loading rate on oxygen reduction reaction (ORR) activity and H 2 O 2 production using the rotating disk electrode and the rotating ring-disk electrode techniques. We prepared carbon-supported CoSe 2 nanoparticles with different nominal loading rates and evaluated these samples by means of powder X-ray diffraction. All the catalysts had an OCP value of 0.81 V vs. RHE. H 2 O 2 production during the ORR process decreased with an increase in catalytic layer thickness. This decrease was related to the CoSe 2 loading on the disk electrode. H 2 O 2 production also decreased with increasing catalytic site density, a phenomenon related to the CoSe 2 loading rate on the carbon substrate. The cathodic current density significantly increased with increasing catalytic layer thickness, but decreased with increasing catalytic site density. In the case of 20 wt% CoSe 2 /C nanoparticles at 22 μg cm -2 , we determined that the transfer process involves about 3.5 electrons.

  12. A Pt-free Electrocatalyst Based on Pyrolized Vinazene-Carbon Composite for Oxygen Reduction Reaction

    International Nuclear Information System (INIS)

    Akinpelu, Akeem; Merzougui, Belabbes; Bukola, Saheed; Azad, Abdul-Majeed; Basheer, Rafil A.; Swain, Greg M.; Chang, Qiaowan; Shao, Minhua

    2015-01-01

    The 2-vinyl-4, 5-dicyanoimidazole (Vinazene) was used as a nitrogen precursor to synthesize a promising non-precious metal (NPM) catalyst for oxygen reduction reaction (ORR). Vinazene together with an iron source was impregnated into a carbon matrix and pyrolyzed at 900 °C in N 2 atmosphere. The structure of the resulting Fe–N–C nanocomposite was analyzed by X-ray photoelectron spectroscopy, Raman spectroscopy and X-ray diffraction. Both rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE) experiments showed excellent ORR activity for the obtained catalyst with low H 2 O 2 formation (∼3.0%) in 0.1 M KOH. The catalyst was found to be rich in mesoporous structure along with high percentage of pyrrolic-N function with surface area of about 673 m 2 g −1 and pore size of 4.2 nm. In addition to its excellent ORR activity, the catalyst showed remarkable tolerance towards methanol oxidation and demonstrates good stability over 10,000 potential cycles (0.6–1.0 V Vs RHE). We believe that this N-rich Vinazene molecule will be beneficial to further development of nitrogen doped carbon electrocatalysts

  13. Ruthenium/Graphene-like Layered Carbon Composite as an Efficient Hydrogen Evolution Reaction Electrocatalyst.

    Science.gov (United States)

    Chen, Zhe; Lu, Jinfeng; Ai, Yuejie; Ji, Yongfei; Adschiri, Tadafumi; Wan, Lijun

    2016-12-28

    Efficient water splitting through electrocatalysis has been studied extensively in modern energy devices, while the development of catalysts with activity and stability comparable to those of Pt is still a great challenge. In this work, we successfully developed a facile route to synthesize graphene-like layered carbon (GLC) from a layered silicate template. The obtained GLC has layered structure similar to that of the template and can be used as support to load ultrasmall Ru nanoparticles on it in supercritical water. The specific structure and surface properties of GLC enable Ru nanoparticles to disperse highly uniformly on it even at a large loading amount (62 wt %). When the novel Ru/GLC was used as catalyst on a glass carbon electrode for hydrogen evolution reaction (HER) in a 0.5 M H 2 SO 4 solution, it exhibits an extremely low onset potential of only 3 mV and a small Tafel slope of 46 mV/decade. The outstanding performance proved that Ru/GLC is highly active catalyst for HER, comparable with transition-metal dichalcogenides or selenides. As the price of ruthenium is much lower than platinum, our study shows that Ru/GLC might be a promising candidate as an HER catalyst in future energy applications.

  14. Charged current antineutrino reactions from 12C at MiniBooNE energies

    International Nuclear Information System (INIS)

    Athar, M. Sajjad; Ahmad, Shakeb; Singh, S. K.

    2007-01-01

    A study of charged current induced antineutrino interactions from nuclei has been done for the intermediate energy antineutrinos and applied to 12 C, relevant for ongoing experiment by MiniBooNE collaboration. The calculations have been done for the quasielastic and inelastic lepton production as well as for the incoherent and the coherent pion production processes. The calculations are done in local density approximation. In the case of the quasielastic reaction the effects of Pauli blocking, Fermi motion effects, renormalization of weak transition strengths in nuclear medium and the Coulomb distortion of the outgoing lepton have been taken into account. For the inelastic processes the calculations have been done in the Δ dominance model and take into account the effect of Pauli blocking, Fermi motion of the nucleon, and renormalization of Δ properties in a nuclear medium. The effect of final state interactions of pions is also taken into account. The numerical results for the total cross sections for the charged current quasielastic scattering and incoherent pion production processes are compared with earlier experimental results available in freon and freon-propane. It is found that nuclear medium effects give strong reduction in the cross sections leading to satisfactory agreement with the available data

  15. Carbon-supported cubic CoSe2 catalysts for oxygen reduction reaction in alkaline medium

    International Nuclear Information System (INIS)

    Feng Yongjun; Alonso-Vante, Nicolas

    2012-01-01

    Highlights: ► Cubic CoSe 2 a non-precious metal electrocatalyst for oxygen reduction in KOH. ► The catalyst shows four-electron transfer pathway in overall reaction. ► Catalyst has higher methanol tolerance than commercial Pt/C catalyst. - Abstract: A Carbon-supported CoSe 2 nanocatalyst has been developed as an alternative non-precious metal electrocatalyst for oxygen reduction reaction (ORR) in alkaline medium. The catalyst was prepared via a surfactant-free route and its electrocatalytic activity for the ORR has been investigated in detail in 0.1 M KOH electrolyte at 25 °C using rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE) techniques. The prepared catalyst showed promising catalytic activity towards ORR in a four-electron transfer pathway and higher tolerance to methanol compared to commercial Pt/C catalyst in 0.1 M KOH. To some extent, the increase of CoSe 2 loading on the electrode favors a faster reduction of H 2 O 2 intermediate to H 2 O.

  16. KOH-activated multi-walled carbon nanotubes as platinum supports for oxygen reduction reaction

    Science.gov (United States)

    He, Chaoxiong; Song, Shuqin; Liu, Jinchao; Maragou, Vasiliki; Tsiakaras, Panagiotis

    In the present investigation, multi-walled carbon nanotubes (MWCNTs) thermally treated by KOH were adopted as the platinum supporting material for the oxygen reduction reaction electrocatalysts. FTIR and Raman spectra were used to investigate the surface state of MWCNTs treated by KOH at different temperatures (700, 800, and 900 °C) and showed MWCNTs can be successfully functionalized. The structural properties of KOH-activated MWCNTs supported Pt were determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM), and their electrochemical performance was evaluated by the aid of cyclic voltammetry (CV) and rotating disk electrode (RDE) voltammetry. According to the experimental findings of the present work, the surrface of MWCNTs can be successfully functionalized with oxygen-containing groups after activation by KOH, favoring the good dispersion of Pt nanoparticles with narrow size distribution. The as-prepared Pt catalysts supported on KOH treated MWCNTs at higher temperature, possess higher electrochemical surface area and exhibit desirable activity towards oxygen reduction reaction (ORR). More precisely, it has been found that the electrochemical active area of Pt/MWCNTs-900 is approximately two times higher than that of Pt/MWCNTs. It can be concluded that KOH activation is an effective way to decorate MWCNTs' surface with oxygen-containing groups and bigger surface area, which makes them more suitable as electrocatalyst support materials.

  17. 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.

  18. A 12-Day Course of Imiquimod 5% for the Treatment of Actinic Keratosis: Effectiveness and Local Reactions.

    Science.gov (United States)

    Serra-Guillén, C; Nagore, E; Llombart, B; Sanmartín, O; Requena, C; Calomarde, L; Guillén, C

    2018-04-01

    Imiquimod is an excellent option for patients with actinic keratosis, although its use may be limited by the long course of treatment required (4 weeks) and the likelihood of local skin reactions. The objectives of the present study were to demonstrate the effectiveness of a 12-day course of imiquimod 5% for the treatment of actinic keratosis and to examine the association between treatment effectiveness and severity of local reactions. We included patients with at least 8 actinic keratoses treated with imiquimod 5% cream for 12 consecutive days. Local reactions were classified as mild, moderate, or severe. The statistical analysis of the association between local reactions and clinical response was based on the Pearson χ 2 test and the Spearman rank correlation test. Sixty-five patients completed the study. Complete response was recorded in 52.3% and partial response in 75.4%. We found a statistically significant association between severity of the local reaction and response to treatment in both the Pearson χ 2 test and the Spearman rank correlation test. A 12-day course of imiquimod 5% proved effective for the treatment of actinic keratosis. Severity of local reactions during treatment was correlated with clinical response. Copyright © 2017 AEDV. Publicado por Elsevier España, S.L.U. All rights reserved.

  19. Electrodeposition of Pd based binary catalysts on Carbon paper via surface limited redox-replacement reaction for oxygen reduction reaction

    CSIR Research Space (South Africa)

    Modibedi, RM

    2014-05-01

    Full Text Available Direct alcohol fuel cells (DAFCs) continue to extensive attention as potential power sources for portable and stationary applications. The oxygen reduction reaction (ORR) involving the four electron transfer remains a challenge for DAFCs due to its...

  20. A kinetic study of the reaction of water vapor and carbon dioxide on uranium; Cinetique de la reaction de la vapeur d'eau et du dioxyde de carbone sur l'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Santon, J P [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1964-09-15

    The kinetic study of the reaction of water vapour and carbon dioxide with uranium has been performed by thermogravimetric methods at temperatures between 160 and 410 deg G in the first case, 350 and 1050 deg C in the second: Three sorts of uranium specimens were used: uranium powder, thin evaporated films, and small spheres obtained from a plasma furnace. The experimental results led in the case of water vapour, to a linear rate of reaction controlled by diffusion at the lower temperatures, and by a surface reaction at the upper ones. In the case of carbon dioxide, a parabolic law has been found, controlled by diffusional processes. (author) [French] L'etude cinetique de la reaction de la vapeur d'eau et du dioxyde de carbone sur l'uranium a ete entreprise au moyen de methodes thermogravimetriques, dans te premier cas entre 160 et 410 deg C et dans le second entre 350 et 1050 deg C. Le materiau utilise se presentait sous trois formes: poudres, couches minces evaporees et billes obtenues par fusion en chalumeau a plasma. Les resultats experimentaux ont permis de mettre en evidence, dans le cas de la vapeur d'eau, une cinetique lineaire controlee par la diffusion a basse temperature et d'interface a haute temperature. Dans le cas du dioxyde de carbone par contre, on trouve une cinetique parabolique controlee par la diffusion. (auteur)

  1. A bio-inspired N-doped porous carbon electrocatalyst with hierarchical superstructure for efficient oxygen reduction reaction

    Science.gov (United States)

    Miao, Yue-E.; Yan, Jiajie; Ouyang, Yue; Lu, Hengyi; Lai, Feili; Wu, Yue; Liu, Tianxi

    2018-06-01

    The bio-inspired hierarchical "grape cluster" superstructure provides an effective integration of one-dimensional carbon nanofibers (CNF) with isolated carbonaceous nanoparticles into three-dimensional (3D) conductive frameworks for efficient electron and mass transfer. Herein, a 3D N-doped porous carbon electrocatalyst consisting of carbon nanofibers with grape-like N-doped hollow carbon particles (CNF@NC) has been prepared through a simple electrospinning strategy combined with in-situ growth and carbonization processes. Such a bio-inspired hierarchically organized conductive network largely facilitates both the mass diffusion and electron transfer during the oxygen reduction reactions (ORR). Therefore, the metal-free CNF@NC catalyst demonstrates superior catalytic activity with an absolute four-electron transfer mechanism, strong methanol tolerance and good long-term stability towards ORR in alkaline media.

  2. Heavily Graphitic-Nitrogen Self-doped High-porosity Carbon for the Electrocatalysis of Oxygen Reduction Reaction

    Science.gov (United States)

    Feng, Tong; Liao, Wenli; Li, Zhongbin; Sun, Lingtao; Shi, Dongping; Guo, Chaozhong; Huang, Yu; Wang, Yi; Cheng, Jing; Li, Yanrong; Diao, Qizhi

    2017-11-01

    Large-scale production of active and stable porous carbon catalysts for oxygen reduction reaction (ORR) from protein-rich biomass became a hot topic in fuel cell technology. Here, we report a facile strategy for synthesis of nitrogen-doped porous nanocarbons by means of a simple two-step pyrolysis process combined with the activation of zinc chloride and acid-treatment process, in which kidney bean via low-temperature carbonization was preferentially adopted as the only carbon-nitrogen sources. The results show that this carbon material exhibits excellent ORR electrocatalytic activity, and higher durability and methanol-tolerant property compared to the state-of-the-art Pt/C catalyst for the ORR, which can be mainly attributed to high graphitic-nitrogen content, high specific surface area, and porous characteristics. Our results can encourage the synthesis of high-performance carbon-based ORR electrocatalysts derived from widely-existed natural biomass.

  3. ATOMIC-LEVEL IMAGING OF CO2 DISPOSAL AS A CARBONATE MINERAL: OPTIMIZING REACTION PROCESS DESIGN; A

    International Nuclear Information System (INIS)

    M.J. McKelvy; R. Sharma; A.V.G. Chizmeshya; H. Bearat; R.W. Carpenter

    2001-01-01

    Fossil fuels, especially coal, can support the energy demands of the world for centuries to come, if the environmental problems associated with CO(sub 2) emissions can be overcome. Permanent and safe methods for CO(sub 2) capture and disposal/storage need to be developed. Mineralization of stationary-source CO(sub 2) emissions as carbonates can provide such safe capture and long-term sequestration. Mg-rich lamellar-hydroxide based minerals (e.g., brucite and serpentine) offer a class of widely available, low-cost materials, with intriguing mineral carbonation potential. Carbonation of such materials inherently involves dehydroxylation, which can disrupt the material down to the atomic level. As such, controlled dehydroxylation, before and/or during carbonation, may provide an important parameter for enhancing carbonation reaction processes. Mg(OH)(sub 2) was chosen as the model material for investigating lamellar hydroxide mineral dehydroxylation/carbonation mechanisms due to (i) its structural and chemical simplicity, (ii) interest in Mg(OH)(sub 2) gas-solid carbonation as a potentially cost-effective CO(sub 2) mineral sequestration process component, and (iii) its structural and chemical similarity to other lamellar-hydroxide-based minerals (e.g., serpentine-based minerals) whose carbonation reaction processes are being explored due to their low-cost CO(sub 2) sequestration potential. Fundamental understanding of the mechanisms that govern dehydroxylation/carbonation processes is essential for minimizing the cost of any lamellar-hydroxide-based mineral carbonation sequestration process. This report covers the third year progress of this grant, as well as providing an integrated overview of the progress in years 1-3, as we have been granted a one-year no-cost extension to wrap up a few studies and publications to optimize project impact

  4. Study for the charge symmetric systems, 12C+13N and 12C+13C with the orthogonalized coupled-reaction-channel method

    International Nuclear Information System (INIS)

    Imanishi, B.; Denisov, V.; Motobayashi, T.

    1996-10-01

    The charge-symmetric scattering systems, 12 C+ 13 N and 12 C+ 13 C have been investigated by using the orthogonalized coupled-reaction-channel (OCRC) method with the basis functions of the elastic, inelastic and transfer channels defined by the single-particle states, 1p1/2, 2s1/2, 1d5/2 and 1d3/2 of the valence nucleon in 13 N or 13 C. The data of the elastic scattering of 13 N on 12 C measured by Lienard et al. have been explained consistently with the data of the elastic and inelastic scattering of the 12 C+ 13 C system. The CRC effects both on the above systems are very strong, although those on the 12 C+ 13 N system are fairly weaker than the 12 C+ 13 C system. The role of the highly excited single-particle states 1d3/2 is particularly important in the formation of a specific CRC scheme, i.e., the formation of the covalent molecules due to the hybridization caused by the mixing of the different parity single-particle states. The fusion cross sections of the 12 C+ 13 C system at energies below the Coulomb barrier are strongly enhanced as a result of the strong CRC effects as compared with those of the 12 C+ 12 C system, while in 12 C+ 13 N system the enhancement of the sub-barrier fusion has not been observed. The above absorption mechanism for the 12 C+ 13 C system explains the lack of the molecular-resonance phenomena observed in the 12 C+ 12 C system. We check the effects of the dipole (E1) transition of the valence nucleon in 13 N (and also in 13 C) due to the core-core Coulomb interaction in the scattering at sub-barrier energies. The effects are not appreciable. (author)

  5. Iron-catalysed fluoroaromatic coupling reactions under catalytic modulation with 1,2-bis(diphenylphosphino)benzene.

    Science.gov (United States)

    Hatakeyama, Takuji; Kondo, Yoshiyuki; Fujiwara, Yu-Ichi; Takaya, Hikaru; Ito, Shingo; Nakamura, Eiichi; Nakamura, Masaharu

    2009-03-14

    A catalytic amount of 1,2-bis(diphenylphosphino)benzene (DPPBz) achieves selective cleavage of sp(3)-carbon-halogen bond in the iron-catalysed cross-coupling between polyfluorinated arylzinc reagents and alkyl halides, which was unachievable with a stoichiometric modifier such as TMEDA; the selective iron-catalysed fluoroaromatic coupling provides easy and practical access to polyfluorinated aromatic compounds.

  6. Relation between separation factor of carbon isotope and chemical reaction of CO2 with amine in nonaqueous solvent

    International Nuclear Information System (INIS)

    Takeshita, Kenji; Kitamoto, Asashi

    1989-01-01

    The separation factor for carbon isotope exchange reaction between CO 2 and amine in nonaqueous solvent was related to absorption reaction of CO 2 in a solution. The test solutions were mixtures of primary amine (such as butylamine and tert-butylamine) or secondary amine (such as diethylamine, dipropylamine and dibutylamine) diluted with nonpolar solvent (octane or triethyalmine) or polar solvent (methanol), respectively. The isotope exchange reaction consists of three steps related to chemical reaction of CO 2 in amine and nonaqueous solvent mixture, namely the reaction between CO 2 and carbamic acid, that between CO 2 and amine carbamate, and that between CO 2 and carbamic ion. Above all, the isotope separation factor between CO 2 and carbamic acid had the highest value. The overall separation factor can be higher in amine-nonaqueous solvent mixture where the concentration of carbamic acid becomes higher. (author)

  7. Cobalt-Embedded Nitrogen-Rich Carbon Nanotubes Efficiently Catalyze Hydrogen Evolution Reaction at All pH Values

    Czech Academy of Sciences Publication Activity Database

    Zou, X.; Huang, X.; Goswami, A.; Silva, R.; Sathe, B. R.; Mikmeková, Eliška; Asefa, T.

    2014-01-01

    Roč. 53, č. 17 (2014), s. 4372-4376 ISSN 1433-7851 R&D Projects: GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : carbon nanotubes * cobalt nanoparticles * electrocatalysis * hydrogen evolution reaction * water splitting Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 11.261, year: 2014

  8. Characterisation of Dissolved Organic Carbon by Thermal Desorption - Proton Transfer Reaction - Mass Spectrometry

    Science.gov (United States)

    Materić, Dušan; Peacock, Mike; Kent, Matthew; Cook, Sarah; Gauci, Vincent; Röckmann, Thomas; Holzinger, Rupert

    2017-04-01

    Dissolved organic carbon (DOC) is an integral component of the global carbon cycle. DOC represents an important terrestrial carbon loss as it is broken down both biologically and photochemically, resulting in the release of carbon dioxide (CO2) to the atmosphere. The magnitude of this carbon loss can be affected by land management (e.g. drainage). Furthermore, DOC affects autotrophic and heterotrophic processes in aquatic ecosystems, and, when chlorinated during water treatment, can lead to the release of harmful trihalomethanes. Numerous methods have been used to characterise DOC. The most accessible of these use absorbance and fluorescence properties to make inferences about chemical composition, whilst high-performance size exclusion chromatography can be used to determine apparent molecular weight. XAD fractionation has been extensively used to separate out hydrophilic and hydrophobic components. Thermochemolysis or pyrolysis Gas Chromatography - Mass Spectrometry (GC-MS) give information on molecular properties of DOC, and 13C NMR spectroscopy can provide an insight into the degree of aromaticity. Proton Transfer Reaction - Mass Spectrometry (PTR-MS) is a sensitive, soft ionisation method suitable for qualitative and quantitative analysis of volatile and semi-volatile organic vapours. So far, PTR-MS has been used in various environmental applications such as real-time monitoring of volatile organic compounds (VOCs) emitted from natural and anthropogenic sources, chemical composition measurements of aerosols etc. However, as the method is not compatible with water, it has not been used for analysis of organic traces present in natural water samples. The aim of this work was to develop a method based on thermal desorption PTR-MS to analyse water samples in order to characterise chemical composition of dissolved organic carbon. We developed a clean low-pressure evaporation/sublimation system to remove water from samples and thermal desorption system to introduce

  9. Unimolecular HCl and HF elimination reactions of 1,2-dichloroethane, 1,2-difluoroethane, and 1,2-chlorofluoroethane: assignment of threshold energies.

    Science.gov (United States)

    Duncan, Juliana R; Solaka, Sarah A; Setser, D W; Holmes, Bert E

    2010-01-21

    The recombination of CH(2)Cl and CH(2)F radicals generates vibrationally excited CH(2)ClCH(2)Cl, CH(2)FCH(2)F, and CH(2)ClCH(2)F molecules with about 90 kcal mol(-1) of energy in a room temperature bath gas. New experimental data for CH(2)ClCH(2)F have been obtained that are combined with previously published studies for C(2)H(4)Cl(2) and C(2)H(4)F(2) to define reliable rate constants of 3.0 x 10(8) (C(2)H(4)F(2)), 2.4 x 10(8) (C(2)H(4)Cl(2)), and 1.9 x 10(8) (CH(2)ClCH(2)F) s(-1) for HCl and HF elimination. The product branching ratio for CH(2)ClCH(2)F is approximately 1. These experimental rate constants are compared to calculated statistical rate constants (RRKM) to assign threshold energies for HF and HCl elimination. The calculated rate constants are based on transition-state models obtained from calculations of electronic structures; the energy levels of the asymmetric, hindered, internal rotation were directly included in the state counting to obtain a more realistic measure for the density of internal states for the molecules. The assigned threshold energies for C(2)H(4)F(2) and C(2)H(4)Cl(2) are both 63 +/- 2 kcal mol(-1). The threshold energies for CH(2)ClCH(2)F are 65 +/- 2 (HCl) and 63 +/- 2 (HF) kcal mol(-1). These threshold energies are 5-7 kcal mol(-1) higher than the corresponding values for C(2)H(5)Cl or C(2)H(5)F, and beta-substitution of F or Cl atoms raises threshold energies for HF or HCl elimination reactions. The treatment presented here for obtaining the densities of states and the entropy of activation from models with asymmetric internal rotations with high barriers can be used to judge the validity of using a symmetric internal-rotor approximation for other cases. Finally, threshold energies for the 1,2-fluorochloroethanes are compared to those of the 1,1-fluorochloroethanes to illustrate substituent effects on the relative energies of the isomeric transition states.

  10. Carbon monoxide gas sensing using zinc oxide deposited by successive ionic layer adhesion and reaction

    Science.gov (United States)

    Florido, E. A.; Dagaas, N. A. C.

    2017-05-01

    This study was aimed to determine the carbon monoxide (CO) gas sensing capability of zinc oxide (ZnO) film fabricated by successive ionic layer adsorption and reaction (SILAR) on glass substrate. Films consisting of a mixture of flower-like clusters of ZnO nanorods and nanowires were observed using scanning electron microscopy (SEM). Current-voltage characterization of the samples showed an average resistivity of 13.0 Ω-m. Carbon monoxide gas was synthesized by mixing the required amount of formic acid and excess sulfuric acid to produce CO gas concentrations of 100, 200, 300, 400, and 500 parts per million (ppm) v/v with five trials for each concentration. Two sets of data were obtained. One set consisted of the voltage response of the single film sensor while the other set were obtained from the double film sensor. The voltage response for the single film sensor and the double film sensor showed an average sensitivity of 0.0038 volts per ppm and 0.0024 volts per ppm, respectively. The concentration the single film can detect with a 2V output is 526 ppm while the double film sensor can detect up to 833 ppm with a 2V output. This shows that using the double film sensor is advantageous compared to single film sensor, because of its higher concentration range due to the larger surface area for the gas to interact. Moreover, the measured average resistance for the single film sensor was 10 MΩ while for the double film sensor the average resistance was 5 MΩ.

  11. Interaction of 2,4,6-trichlorophenol with high carbon iron filings: Reaction and sorption mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Alok [Environmental Engineering and Management Programme, Department of Civil Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Bose, Purnendu [Environmental Engineering and Management Programme, Department of Civil Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India)], E-mail: pbose@iitk.ac.in

    2009-05-15

    Reductive dehalogenation of 2,4,6-trichlorophenol (2,4,6-TCP) by two types of high carbon iron filings (HCIF), HCIF-1 and HCIF-2 was studied in batch reactors. While the iron, copper, manganese and carbon content of the two types of HCIF was similar, the specific surface area of HCIF-1 and HCIF-2 were 1.944 and 3.418 m{sup 2} g{sup -1}, respectively. During interaction with HCIF-1, 2,4,6-TCP adsorbed on HCIF-1 surface resulting in rapid reduction of aqueous phase 2,4,6-TCP concentration. However, reductive dehalogenation of 2,4,6-TCP was negligible. During interaction between 2,4,6-TCP and HCIF-2, both 2,4,6-TCP adsorption on HCIF-2, and 2,4,6,-TCP dechlorination was observed. 2,4,6-TCP partitioning between solid and aqueous phase could be described by a Freundlich isotherm, while 2,4,6-TCP dechlorination could be described by an appropriate rate expression. A mathematical model was developed for describing the overall interaction of 2,4,6-TCP with HCIF-2, incorporating simultaneous adsorption/desorption and dechlorination reactions of 2,4,6-TCP with the HCIF surface. 2,4-Dichlorophenol (2,4-DCP), 2-chlorophenol (2-CP) and minor amounts of 4-chlorophenol (4-CP) evolved as 2,4,6-TCP dechlorination by-products. The evolved 2,4-DCP partitioned strongly to the HCIF surface. 4-CP and 2-CP accumulated in the aqueous phase. No transformation of 2-CP or 4-CP to phenol was observed.

  12. Reaction Coordinate, Free Energy, and Rate of Intramolecular Proton Transfer in Human Carbonic Anhydrase II.

    Science.gov (United States)

    Paul, Sanjib; Paul, Tanmoy Kumar; Taraphder, Srabani

    2018-03-22

    The role of structure and dynamics of an enzyme has been investigated at three different stages of its function including the chemical event it catalyzes. A one-pot computational method has been designed for each of these stages on the basis of classical and/or quantum mechanical-molecular mechanical molecular dynamics and transition path sampling simulations. For a pair of initial and final states A and B separated by a high free-energy barrier, using a two-stage selection process, several collective variables (CVs) are identified that can delineate A and B. However, these CVs are found to exhibit strong cross-coupling over the transition paths. A set of mutually orthogonal order parameters is then derived from these CVs and an optimal reaction coordinate, r, determined applying half-trajectory likelihood maximization along with a Bayesian information criterion. The transition paths are also used to project the multidimensional free energy surface and barrier crossing dynamics along r. The proposed scheme has been applied to the rate-determining intramolecular proton transfer reaction of the well-known enzyme human carbonic anhydrase II. The potential of mean force, F( r), in the absence of the chemical step is found to reproduce earlier results on the equilibrium population of two side-chain orientations of key residue His-64. Estimation of rate constants, k, from mean first passage times for the three different stages of catalysis shows that the rate-determining step of intramolecular proton transfer occurs with k ≃ 1.0 × 10 6 s -1 , in close agreement with known experimental results.

  13. Reactivity of Single-Walled Carbon Nanotubes in the Diels-Alder Cycloaddition Reaction: Distortion-Interaction Analysis along the Reaction Pathway.

    Science.gov (United States)

    Li, Yingzi; Osuna, Sílvia; Garcia-Borràs, Marc; Qi, Xiaotian; Liu, Song; Houk, Kendall N; Lan, Yu

    2016-08-26

    Diels-Alder cycloaddition is one of the most powerful tools for the functionalization of single-walled carbon nanotubes (SWCNTs). Density functional theory at the B3-LYP level of theory has been used to investigate the reactivity of different-diameter SWCNTs (4-9,5) in Diels-Alder reactions with 1,3-butadiene; the reactivity was found to decrease with increasing SWCNT diameter. Distortion/interaction analysis along the whole reaction pathway was found to be a better way to explore the reactivity of this type of reaction. The difference in interaction energy along the reaction pathway is larger than that of the corresponding distortion energy. However, the distortion energy plots for these reactions show the same trend. Therefore, the formation of the transition state can be determined from the interaction energy. A lower interaction energy leads to an earlier transition state, which indicates a lower activation energy. The computational results also indicate that the original distortion of the SWCNTs leads to an increase in the reactivity of the SWCNTs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Identification of catalytic sites in cobalt-nitrogen-carbon materials for the oxygen reduction reaction.

    Science.gov (United States)

    Zitolo, Andrea; Ranjbar-Sahraie, Nastaran; Mineva, Tzonka; Li, Jingkun; Jia, Qingying; Stamatin, Serban; Harrington, George F; Lyth, Stephen Mathew; Krtil, Petr; Mukerjee, Sanjeev; Fonda, Emiliano; Jaouen, Frédéric

    2017-10-16

    Single-atom catalysts with full utilization of metal centers can bridge the gap between molecular and solid-state catalysis. Metal-nitrogen-carbon materials prepared via pyrolysis are promising single-atom catalysts but often also comprise metallic particles. Here, we pyrolytically synthesize a Co-N-C material only comprising atomically dispersed cobalt ions and identify with X-ray absorption spectroscopy, magnetic susceptibility measurements and density functional theory the structure and electronic state of three porphyrinic moieties, CoN 4 C 12 , CoN 3 C 10,porp and CoN 2 C 5 . The O 2 electro-reduction and operando X-ray absorption response are measured in acidic medium on Co-N-C and compared to those of a Fe-N-C catalyst prepared similarly. We show that cobalt moieties are unmodified from 0.0 to 1.0 V versus a reversible hydrogen electrode, while Fe-based moieties experience structural and electronic-state changes. On the basis of density functional theory analysis and established relationships between redox potential and O 2 -adsorption strength, we conclude that cobalt-based moieties bind O 2 too weakly for efficient O 2 reduction.Nitrogen-doped carbon materials with atomically dispersed iron or cobalt are promising for catalytic use. Here, the authors show that cobalt moieties have a higher redox potential, bind oxygen more weakly and are less active toward oxygen reduction than their iron counterpart, despite similar coordination.

  15. Investigation of Thermochemistry Associated with the Carbon–Carbon Coupling Reactions of Furan and Furfural Using ab Initio Methods

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Cong; Assary, Rajeev S.; Curtiss, Larry A.

    2014-06-26

    Upgrading of furan and small oxygenates obtained from the decomposition of cellulosic materials via formation of carbon-carbon bonds is critical to effective conversion of biomass to liquid transportation fuels. Simulation-driven molecular level understanding of carbon-carbon bond formation is required to design efficient catalysts and processes. Accurate quantum chemical methods are utilized here to predict the reaction energetics for conversion of furan (C4H4O) to C5-C8 ethers and the transformation of furfural (C5H6O2) to C13-C26 alkanes. Furan, can be coupled with various C1 to C4 lower molecular weight carbohydrates obtained from the pyrolysis via Diels-Alder type reactions in the gas phase to produce C5-C8 cyclic ethers. The computed reaction barriers for these reactions (~25 kcal/mol) are lower than the cellulose activation or decomposition reactions (~50 kcal/mol). Cycloaddition of C5-C8 cyclo-ethers with furans can also occur in the gas phase, and the computed activation energy is similar to that of the first Diels-Alder reaction. Furfural, obtained from biomass, can be coupled with aldehydes or ketones with α-hydrogen atoms to form longer chain aldol products and these aldol products can undergo vapor phase hydrocycloaddition (activation barrier of ~20 kcal/mol) to form the precursors of C26 cyclic hydrocarbons. These thermochemical studies provide the basis for further vapor phase catalytic studies required for upgrading of furans/furfurals to longer chain hydrocarbons.

  16. Carbonates in leaching reactions in context of {sup 14}C dating

    Energy Technology Data Exchange (ETDEWEB)

    Michalska, Danuta, E-mail: danamich@amu.edu.pl [Institute of Geology, Faculty of Geographical and Geological Sciences, Adam Mickiewicz University, ul. Makow Polnych 16, 61-606 Poznan (Poland); Czernik, Justyna, E-mail: justyna.czernik@gmail.com [Poznań Radiocarbon Laboratory, ul. Rubież 46, 61-612 Poznań (Poland)

    2015-10-15

    Lime mortars as a mixture of binder and aggregate may contain carbon of various origins. If the mortars are made of totally burnt lime, radiocarbon dating of binder yields the real age of building construction. The presence of carbonaceous aggregate has a significant influence on the {sup 14}C measurements results and depending on the type of aggregate and fraction they may cause overaging. Another problem, especially in case of hydraulic mortars that continue to be chemically active for a very long time, is the recrystallization usually connected with rejuvenation of the results but also, depending on local geological structures, with so called reservoir effect yielding apparent ages. An attempt in separating the binder from other carbonaceous components successfully was made for samples from Israel by Nawrocka-Michalska et al. (2007). The same preparation procedure, after taking into account the petrographic composition, was used for samples coming from Poland, Nawrocka et al. (2009). To verify the procedure used previously for non-hydraulic samples determination an experimental tests on carbonaceous mortars with crushed bricks from Novae in Bulgaria were made. Additionally, to identify different carbonaceous structures and their morphology, a cathodoluminescence and scanning electron microscope with electron dispersive spectrometer were applied. The crushed bricks and brick dust used in mortars production process have been interpreted as an alternative use to other pozzolanic materials. The reaction between lime and pozzolanic additives take place easily and affects the rate and course of carbonates decomposition in orthophosphric acid, during the samples pretreatment for dating. The composition of the Bulgarian samples together with influence of climate conditions on mortar carbonates do not allow for making straightforward conclusions in chronology context, but gives some new guidelines in terms of hydraulic mortars application for dating. This work has mainly

  17. Carbonates in leaching reactions in context of "1"4C dating

    International Nuclear Information System (INIS)

    Michalska, Danuta; Czernik, Justyna

    2015-01-01

    Lime mortars as a mixture of binder and aggregate may contain carbon of various origins. If the mortars are made of totally burnt lime, radiocarbon dating of binder yields the real age of building construction. The presence of carbonaceous aggregate has a significant influence on the "1"4C measurements results and depending on the type of aggregate and fraction they may cause overaging. Another problem, especially in case of hydraulic mortars that continue to be chemically active for a very long time, is the recrystallization usually connected with rejuvenation of the results but also, depending on local geological structures, with so called reservoir effect yielding apparent ages. An attempt in separating the binder from other carbonaceous components successfully was made for samples from Israel by Nawrocka-Michalska et al. (2007). The same preparation procedure, after taking into account the petrographic composition, was used for samples coming from Poland, Nawrocka et al. (2009). To verify the procedure used previously for non-hydraulic samples determination an experimental tests on carbonaceous mortars with crushed bricks from Novae in Bulgaria were made. Additionally, to identify different carbonaceous structures and their morphology, a cathodoluminescence and scanning electron microscope with electron dispersive spectrometer were applied. The crushed bricks and brick dust used in mortars production process have been interpreted as an alternative use to other pozzolanic materials. The reaction between lime and pozzolanic additives take place easily and affects the rate and course of carbonates decomposition in orthophosphric acid, during the samples pretreatment for dating. The composition of the Bulgarian samples together with influence of climate conditions on mortar carbonates do not allow for making straightforward conclusions in chronology context, but gives some new guidelines in terms of hydraulic mortars application for dating. This work has mainly

  18. Hyperspherical functions and quantum-mechanical three-body problem with application to carbon 12

    International Nuclear Information System (INIS)

    Letz, H.

    1975-01-01

    In this work a system of three identical particles (bosons) interacting by a particular two-body force is discussed. Using the complete set of the hyperspherical functions (K-harmonics), analytical expressions for eigenvalues and wave functions of the stationary states are found. The numerical evaluation gives a level sequence for a definite pair of potential parameters similar to that of the nucleus carbon 12

  19. Electronic Switch in the Carbon-Centered [Re12CS17(CN6] n−Nanocluster

    Directory of Open Access Journals (Sweden)

    Gabuda SP

    2009-01-01

    Full Text Available Abstract An abrupt change in internuclear Re–Re distances between {Re6} subunits in the carbon-centered [Re12μ6-CS17(CN6] n−complexes caused by the change of the oxidation state (n = 6, 8 is first theoretically shown to be possibly controlled by an external electric field.13C NMR signal is shown to change over ~400 ppm (~37G for μ6-C atom together withn. Thereby, the metal cluster [Re12μ6-CS17(CN6] n−can be considered as a perspective model of a molecular switch.

  20. Self-assembled dopamine nanolayers wrapped carbon nanotubes as carbon-carbon bi-functional nanocatalyst for highly efficient oxygen reduction reaction and antiviral drug monitoring

    Science.gov (United States)

    Khalafallah, Diab; Akhtar, Naeem; Alothman, Othman Y.; Fouad, H.; Abdelrazek khalil, Khalil

    2017-09-01

    Oxygen reduction reaction (ORR) catalysts are the heart of eco-friendly energy resources particularly low temperature fuel cells. Although valuable efforts have been devoted to synthesize high performance catalysts for ORR, considerable challenges are extremely desirable in the development of energy technologies. Herein, we report a simple self-polymerization method to build a thin film of dopamine along the tubular nanostructures of multi-walled carbon nanotubes (CNT) in a weak alkaline solution. The dopamine@CNT hybrid (denoted as DA@CNT) reveals an enhanced electrocatalytic activity towards ORR with highly positive onset potential and cathodic current as a result of their outstanding features of longitudinal mesoporous structure, high surface area, and ornamentation of DA layers with nitrogen moieties, which enable fast electron transport and fully exposed electroactive sites. Impressively, the as-obtained hybrid afford remarkable electrochemical durability for prolonged test time of 60,000 s compared to benchmark Pt/C (20 wt%) catalyst. Furthermore, the developed DA@CNT electrode was successfully applied to access the quality of antiviral drug named Valacyclovir (VCR). The DA@CNT electrode shows enhanced sensing performance in terms of large linear range (3-75 nM), low limit of detection (2.55 nM) than CNT based electrode, indicating the effectiveness of the DA coating. Interestingly, the synergetic effect of nanostructured DA and CNT can significantly boost the electronic configuration and exposure level of active species for ORR and biomolecule recognition. Therefore, the existing carbon-based porous electrocatalyst may find numerous translational applications as attractive alternative to noble metals in polymer electrolyte membrane fuel cells and quality control assessment of pharmaceutical and therapeutic drugs.

  1. Effect of carbon coating on spontaneous C12A7 whisker formation

    Science.gov (United States)

    Zaikovskii, Vladimir I.; Volodin, Alexander M.; Stoyanovskii, Vladimir O.; Cherepanova, Svetlana V.; Vedyagin, Aleksey A.

    2018-06-01

    A carbon nanoreactor concept was applied to study the stabilization effect of carbon shell on phase composition and morphology of dodecacalcium hepta-aluminate Ca12Al14O33. The starting C12A7 powder was obtained using aluminum and calcium hydroxides as precursors. Carbon shell was formed by a chemical vapor deposition of divinyl at 550 °C. After the calcination at 1400 °C, the product was characterized by X-ray diffraction analysis (XRD) and high resolution transmission electron microscopy (HRTEM). It was observed for a first time that spontaneous formation of calcium aluminate whiskers take place under the conditions described. Each whisker consists of a 'head' (globular particle of 0.5 microns in diameter) and a 'tail' (prolonged whisker of few microns in length and 0.1-0.2 microns in diameter). According to HRTEM, the 'head' is characterized with microcrystal lattice of Ca12Al14O33 compound. XRD data show the presence of CaAl2O4 phase traces. The 'head' and 'tail' of the whisker are covered with structured graphene layers of 10 nm and 3 nm, correspondingly.

  2. Temperature dependence of carbon kinetic isotope effect for the oxidation reaction of ethane by OH radicals under atmospherically relevant conditions

    Science.gov (United States)

    Piansawan, Tammarat; Saccon, Marina; Laumer, Werner; Gensch, Iulia; Kiendler-Scharr, Astrid

    2015-04-01

    Modeling of the global distribution of atmospheric ethane sources and sinks by using the 13C isotopic composition requires accurate knowledge of the carbon kinetic isotope effect (KIE) of its atmospheric removal reactions. The quantum mechanical prediction implies the necessity to elucidate the temperature dependence of KIE within atmospherically relevant temperature range by experiment. In this study, the KIE and its temperature dependence for ethane oxidation by OH radicals was investigated at ambient pressure in a temperature range of 243 K to 303 K. The chemical reactions were carried out in a 15 L PFE reaction chamber, suspended in a thermally controlled oven. The isotope ratios of the gas phase components during the course of the reactions were measured by Thermal Desorption -- Gas Chromatography -- Isotope Ratio Mass Spectrometry (TD-GC-IRMS). For each temperature, the KIE was derived from the temporal evolution of the concentration and stable carbon isotope ratio (δ13C) of ethane using a method adapted from the relative reaction rate concept. The room temperature KIE of the ethane reaction with OH radicals was found to be 6.85 ± 0.32 ‰. This value is in agreement with the previously reported value of 8.57 ± 1.95 ‰ [Anderson et al. 2004] but has a substantially lower uncertainty. The experimental results will be discussed with the KIE temperature dependence predicted by quantum mechanical calculations. Reference: Rebecca S. Anderson, Lin Huang, Richard Iannone, Alexandra E. Thompson, and Jochen Rudolph (2004), Carbon Kinetic Isotope Effects in the Gas Phase Reactions of Light Alkanes and Ethene with the OH Radical at 296 ± 4 K, J. Phys. Chem. A, 108, 11537--11544

  3. Study of the p+{sup 12}C reaction at energies up to 30 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Harada, Masahide; Yamamoto, A.; Yoshioka, S. [Kyushu Univ., Fukuoka (Japan)] [and others

    1998-03-01

    Double differential cross sections of charged-particles emitted in the p+{sup 12}C reaction were measured in the energy region from 14 to 26 MeV. The observed continuous components of emitted protons and {alpha}-particles were analyzed by assuming sequential decay of intermediate reaction products and/or simultaneous breakup process. It was found that the three body simultaneous decay, p+{alpha}+{sup 8}Be, and the sequential decay via p+{sup 12}C{sup *}{sub 3-} and {alpha}+{sup 9}B{sub g.s.} are most important in the proton-induced breakup of {sup 12}C for energies up to 30 MeV. (author)

  4. Synthesis of Fe nanoparticles on polyaniline covered carbon nanotubes for oxygen reduction reaction

    Science.gov (United States)

    Hu, Tian-Hang; Yin, Zhong-Shu; Guo, Jian-Wei; Wang, Cheng

    2014-12-01

    Fe nanoparticles immobilized on polyaniline-covered carbon nanotube (CNT) surfaces (Fe NPs-PANI/CNT) are prepared by reducing FeCl3 in the mixing solution of aniline and CNT. Significantly, the structure of such composites can be effectively optimized by pretreating FeCl3 with sodium citrate (CA). In the absence of CNTs, we found these two routes have large differences in reduction behaviors and different PANI states with varied conductivities. Therefore, the self-assembly mechanism in the preparation is proposed and the controlled self-assembly manner in the pretreating route is disclosed. Under acid condition, both catalysts demonstrate high oxygen reduction reaction (ORR) activity with four-electron pathway, and high electrochemical durability, revealing a promising application in the proton exchange membrane fuel cells. However, the high Tafel slopes relating to the surface red-ox couple and porous conductivity are still the main obstacles to improve their ORR dynamic, and more efforts on these aspects are needed to drive non-noble catalyst application in future.

  5. In situ observation of the reaction of scandium and carbon by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Juarez-Arellano, Erick A., E-mail: eajuarez@unpa.edu.m [Institut fuer Geowissenschaften, Universitaet Frankfurt, Altenhoeferallee 1, 60438 Frankfurt a.M. (Germany); Universidad del Papaloapan, Circuito Central 200, Parque Industrial, Tuxtepec 68301 (Mexico); Winkler, Bjorn [Institut fuer Geowissenschaften, Universitaet Frankfurt, Altenhoeferallee 1, 60438 Frankfurt a.M. (Germany); Vogel, Sven C. [Los Alamos National Laboratory, Lujan Center. Mail Stop H805, Los Alamos, NM 87545 (United States); Senyshyn, Anatoliy [Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Technische Universitaet Muenchen, Lichtenbergstr. 1, D-85747 Garching (Germany); Materialwissenschaft, TU Darmstadt, Petersensstr. 23, D-64287 Darmstadt (Germany); Kammler, Daniel R. [Sandia National Laboratories, Albuquerque, NM 87185 (United States); Avalos-Borja, Miguel [CNyN, UNAM, A. Postal 2681, Ensenada, B.C. (Mexico)

    2011-01-05

    Research highlights: {yields} Exist two ScC cubic phases with B1-structure type differing in site occupancy of C. {yields} A new orthorhombic scandium carbide phase is formed at 1473(50) K. {yields} The recrystallization of alpha-Sc occurs between 1000 and 1223 K. - Abstract: The formation of scandium carbides by reaction of the elements has been investigated by in situ neutron diffraction up to 1823 K. On heating, the recrystallization of {alpha}-Sc occurs between 1000 and 1223 K. The formation of Sc{sub 2}C and ScC (NaCl-B1 type structure) phases has been detected at 1323 and 1373 K, respectively. The formation of a new orthorhombic scandium carbide phase was observed at 1473(50) K. Once the scandium carbides are formed they are stable upon heating or cooling. No other phases were detected in the present study, in which the system was always carbon saturated. The thermal expansion coefficients of all phases have been determined, they are constant throughout the temperature interval studied.

  6. High Oxygen Reduction Reaction Performances of Cathode Materials Combining Polyoxometalates, Coordination Complexes, and Carboneous Supports.

    Science.gov (United States)

    Zhang, Shuangshuang; Oms, Olivier; Hao, Long; Liu, Rongji; Wang, Meng; Zhang, Yaqin; He, Hong-Yan; Dolbecq, Anne; Marrot, Jérôme; Keita, Bineta; Zhi, Linjie; Mialane, Pierre; Li, Bin; Zhang, Guangjin

    2017-11-08

    A series of carbonaceous-supported precious-metal-free polyoxometalate (POM)-based composites which can be easily synthesized on a large scale was shown to act as efficient cathode materials for the oxygen reduction reaction (ORR) in neutral or basic media via a four-electron mechanism with high durability. Moreover, exploiting the versatility of the considered system, its activity was optimized by the judicious choice of the 3d metals incorporated in the {(PW 9 ) 2 M 7 } (M = Co, Ni) POM core, the POM counterions and the support (thermalized triazine-based frameworks (TTFs), fluorine-doped TTF (TTF-F), reduced graphene oxide, or carbon Vulcan XC-72. In particular, for {(PW 9 ) 2 Ni 7 }/{Cu(ethylenediamine) 2 }/TTF-F, the overpotential required to drive the ORR compared well with those of Pt/C. This outstanding ORR electrocatalytic activity is linked with two synergistic effects due to the binary combination of the Cu and Ni centers and the strong interaction between the POM molecules and the porous and highly conducting TTF-F framework. To our knowledge, {(PW 9 ) 2 Ni 7 }/{Cu(ethylenediamine) 2 }/TTF-F represents the first example of POM-based noble-metal-free ORR electrocatalyst possessing both comparable ORR electrocatalytic activity and much higher stability than that of Pt/C in neutral medium.

  7. Effect of one step KOH activation and CaO modified carbon in transesterification reaction

    Science.gov (United States)

    Yacob, Abd Rahim; Zaki, Muhammad Azam Muhammad

    2017-11-01

    In this work, one step activation was introduced using potassium hydroxide (KOH) and calcium oxide (CaO) modified palm kernel shells. Various concentration of calcium oxide was used as catalyst while maintaining the same concentration of potassium hydroxide to activate and impregnate the palm kernel shell before calcined at 500°C for 5 hours. All the prepared samples were characterized using Fourier Transform Infrared (FTIR) and Field Emission Scanning Electron Microscope (FESEM). FTIR analysis of raw palm kernel shell showed the presence of various functional groups. However, after activation, most of the functional groups were eliminated. The basic strength of the prepared samples were determined using back titration method. The samples were then used as base heterogeneous catalyst for the transesterification reaction of rice bran oil with methanol. Analysis of the products were performed using Gas Chromatography Flame Ionization Detector (GC-FID) to calculate the percentage conversion of the biodiesel products. This study shows, as the percentage of one step activation potassium and calcium oxide doped carbon increases thus, the basic strength also increases followed by the increase in biodiesel production. Optimization study shows that the optimum biodiesel production was at 8 wt% catalyst loading, 9:1 methanol: oil molar ratio at 65°C and 6 hours which gives a conversion up to 95%.

  8. Fragment emission in reactions of 18.5-GeV 12C ions with complex nuclei

    International Nuclear Information System (INIS)

    Porile, N.T.; Cole, G.D.

    1982-01-01

    The emission of fragments ranging from 24 Na to 52 Mn in reactions of 18.5 GeV 12 C ions with Cu, Ag, Gd, Ta, Au, and U targets has been studied by means of activation techniques. The experiments involved determination of the fragment production cross sections and thick-target recoil properties. The latter were used to obtain mean fragment kinetic energies and values of β/sub parallel to/, the forward velocity component of the struck nucleus (in units of c). The results are compared with similar data for incident protons of the same total kinetic energy. The data may be used to assess the importance of central collisions in fragment production. Such collisions lead to the near total destruction of both interacting nuclei and the resulting fragments are emitted by a system of intermediate rapidity. In such a process, the factorization hypothesis, which has been shown to be valid for target and projectile fragmentation reactions, should not be obeyed. A test for factorization is performed by means of a relation which states that the ratio of the cross sections for producing fragment /sup A/Z in 12 C reactions to that for producing the same fragment in proton reactions with the same target is unity, provided both cross sections are reduced by the values of the corresponding total reaction cross sections sigma/sub R/, and evaluated for the same total kinetic energy of the projectile. The results of this comparison for the targets studied are presented and discussed

  9. Structural evolution and reaction mechanism of lithium nickelate (LiNiO2 during the carbonation reaction

    Directory of Open Access Journals (Sweden)

    Daniela González-Varela

    2018-03-01

    Full Text Available Lithium nickelate (LiNiO2 was synthesized using the lithium excess method, and then characterized by X-ray diffraction, scanning electron microscopy and N2 adsorption-desorption. Finally, differential thermal and thermogravimetric analyses were performed in CO2 presence, at high temperatures. Results show that LiNiO2 is able to react with CO2 through a complex structural evolution process, where lithium atoms are released to produce Li2CO3, while some nickel atoms are rearranged on different Li1-xNi1+xO2 crystalline phases. LiNiO2-CO2 reaction kinetic parameters were determined assuming a first-order reaction, where kinetic constants tended to increase as a function of temperature. However, kinetic constant values did not follow a linear trend. This atypical behavior was attributed to LiNiO2 sintering and crystalline evolution performed as a function of temperature.

  10. Systematic study of multi-nucleon transfer reactions for 12C + 58Ni and 12C + 56Fe systems at ELab(12C) = 45 and 60 MeV

    International Nuclear Information System (INIS)

    Roy, B.J.; Jha, V.; Biswas, D.C.; Parmar, A.; Mohanty, Biraja; Oswal, M.; Jhingan, Akhil; Nandi, T.

    2013-01-01

    With a motivation to understand the reaction mechanism aspects, systematic study of multi-nucleon transfer in different projectile + target combinations has been made. Data taken at the BARC-TIFR Pelletron - LINAC facility, Mumbai for the systems 18 O+ 206 Pb and 18 O+ 12 C both studied at an incident energy of E( 18 O) = 140.4 MeV are reported in different communications to this proceedings. The present communication reports the measurements for 58 Ni( 12 C, x) and 56 Fe( 12 C, x) at incident 12 C energies of E( 12 C) = 45 and 60 MeV carried out at the pelletron accelerator facility, IUAC, Delhi

  11. Nano-Scale Au Supported on Carbon Materials for the Low Temperature Water Gas Shift (WGS Reaction

    Directory of Open Access Journals (Sweden)

    Paula Sánchez

    2011-12-01

    Full Text Available Au-based catalysts supported on carbon materials with different structures such as graphite (G and fishbone type carbon nanofibers (CNF-F were prepared using two different methods (impregnation and gold-sol to be tested in the water gas shift (WGS reaction. Atomic absorption spectrometry, transmission electron microscopy (TEM, temperature-programmed oxidation (TPO, X-ray diffraction (XRD, Raman spectroscopy, elemental analyses (CNH, N2 adsorption-desorption analysis, temperature-programmed reduction (TPR and temperature-programmed decomposition were employed to characterize both the supports and catalysts. Both the crystalline nature of the carbon supports and the method of gold incorporation had a strong influence on the way in which Au particles were deposited on the carbon surface. The higher crystallinity and the smaller and well dispersed Au particle size were, the higher activity of the catalysts in the WGS reaction was noted. Finally, catalytic activity showed an important dependence on the reaction temperature and steam-to-CO molar ratio.

  12. Hierarchical carbon-coated acanthosphere-like Li4Ti5O12 microspheres for high-power lithium-ion batteries

    Science.gov (United States)

    Sha, Yujing; Xu, Xiaomin; Li, Li; Cai, Rui; Shao, Zongping

    2016-05-01

    In this work, carbon-coated hierarchical acanthosphere-like Li4Ti5O12 microspheres (denoted as AM-LTO) were prepared via a two-step hydrothermal process with low-cost glucose as the organic carbon source. The hierarchical porous microspheres had open structures with diameters of 4-6 μm, which consisted of a bunch of willow leaf-like nanosheets. Each nanosheet was comprised of Li4Ti5O12 nanoparticles that are 20 nm in size and coated by a thin carbon layer. When applied as the anode material for lithium-ion batteries (LIBs), the AM-LTO presented outstanding rate and cycling performance due to its unique morphologies. A high capacity of 145.6 mAh g-1 was achieved for AM-LTO at a rate of 40C (1C = 175 mAh g-1). In contrast, the sample synthesized without glucose as carbon source (denoted as S-LTO) experienced an obvious structural collapse during the hydrothermal reaction and presented a specific capacity of only 67 mAh g-1 at 1C, which further decreased to 14 mAh g-1 at 40C. Further morphological growth of the acanthosphere-like Li4Ti5O12 microspheres and their excellent performance as an anode in LIBs were also discussed in this work.

  13. Thick-target neutron, gamma-ray, and radionuclide production for protons below 12 MeV on nickel and carbon beam-stops

    International Nuclear Information System (INIS)

    Chadwick, M.B.; Young, P.G.; Wilson, W.B.

    1998-03-01

    Nuclear model calculations using the GNASH code are described for protons below 12 MeV incident on nickel and carbon isotopes, for beam stop design in the Los Alamos Accelerator Production of Tritium Low Energy Demonstration Accelerator (LEDA) project. The GNASH calculations apply Hauser-Feshbach and preequilibrium reaction theories and can make use of pre-calculated direct reaction cross sections to low-lying residual nucleus states. From calculated thin target cross sections, thick target 6.7 MeV and 12 MeV proton-induced production of neutrons, gamma rays, and radionuclides are determined. Emission spectra of the secondary neutrons and gamma rays are also determined. The model calculations are validated through comparisons with experimental thin- and thick-target measurements. The results of this work are being utilized as source terms in MCNP analyses for LEDA

  14. {sup 16}O resonances near 4α threshold through {sup 12}C({sup 6}Li,d) reaction

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, M. R. D.; Borello-Lewin, T.; Miyake, H.; Horodynski-Matsushigue, L. B.; Duarte, J. L. M.; Rodrigues, C. L.; Faria, P. Neto de [Instituto de Física, Universidade de São Paulo, Caixa Postal 66318, CEP 05314-970, São Paulo, SP (Brazil); Cunsolo, A.; Cappuzzello, F.; Foti, A.; Agodi, C.; Cavallaro, M. [INFN - Laboratori Nazionali del Sud, Via S. Sofia 62, 95125 Catania (Italy); Napoli, M. di; Ukita, G. M. [Faculdade de Psicologia, Universidade de Santo Amaro, R. Prof. Eneas da Siqueira Neto, 340, CEP 04829-300, São Paulo, SP (Brazil)

    2014-11-11

    Several narrow alpha resonant {sup 16}O states were detected through the {sup 12}C({sup 6}Li,d) reaction, in the range of 13.5 to 17.5 MeV of excitation energy. The reaction was measured at a bombarding energy of 25.5 MeV employing the São Paulo Pelletron-Enge-Spectrograph facility and the nuclear emulsion technique. Experimental angular distributions associated with natural parity quasi-bound states around the 4α threshold are presented and compared to DWBA predictions. The upper limit for the resonance widths obtained is near the energy resolution (15 keV)

  15. Effect of temperature on the reaction pathway of calcium carbonate formation via precursor phases

    Science.gov (United States)

    Purgstaller, Bettina; Mavromatis, Vasileios; Konrad, Florian; Dietzel, Martin

    2016-04-01

    It has been earlier postulated that some biogenic and sedimentary calcium carbonate (CaCO3) minerals (e.g. calcite and aragonite) are secondary in origin and have originally formed via a metastable calcium carbonate precursor phase (e.g. amorphous CaCO3, [1-2]). Such formation pathways are likely affected by various physicochemical parameters including aqueous Mg and temperature. In an effort to improve our understanding on the formation mechanism of CaCO3 minerals, precipitation experiments were carried out by the addition of a 0.6 M (Ca,Mg)Cl2 solution at distinct Mg/Ca ratios (1/4 and 1/8) into a 1 M NaHCO3 solution under constant pH conditions(8.3 ±0.1). The formation of CaCO3 was systematically examined as a function of temperature (6, 12, 18 and 25 ±0.3° C). During the experimental runs mineral precipitation was monitored by in situ Raman spectroscopy as well as by continuous sampling and analyzing of precipitates and reactive solutions. The results revealed two pathways of CaCO3 formation depending on the initial Mg/Ca ratio and temperature: (i) In experiments with a Mg/Ca ratio of 1/4 at ≤ 12° C as well as in experiments with a Mg/Ca ratio of 1/8 at ≤ 18° C, ikaite (CaCO3 6H2O) acts as a precursor phase for aragonite formation. (ii) In contrast higher temperatures induced the formation of Mg-rich amorphous CaCO3 (Mg-ACC) which was subsequently transformed to Mg-rich calcite. In situ Raman spectra showed that the transformation of Mg-ACC to Mg-calcite occurs at a higher rate (˜ 8 min) compared to that of ikaite to aragonite (> 2 h). Thus, the formation of aragonite rather than of Mg-calcite occurs due to the slower release of Ca2+and CO32- ions into the Mg-rich reactive solution during retarded ikaite dissolution. This behavior is generally consistent with the observation that calcite precipitation is inhibited at elevated aqueous Mg/Ca ratios. [1] Addadi L., Raz S. and Weiner S. (2003) Advanced Materials 15, 959-970. [2] Rodriguez-Blanco J. D

  16. Study of secondary particles produced in central 12C-nucleus reactions at 4.5 AGeV

    International Nuclear Information System (INIS)

    Saleem Khan, M.; Shukla, Praveen Prakash; Khushnood, H.

    2014-01-01

    Study of secondary charged particles produced in central relativistic heavy ion interactions is attracting a great deal of attention during the recent years. It may be due to the fact that the study of totally disintegrated events produced in heavy ion collisions in which almost the whole projectile takes part in the reactions. On the basis of the study of the totally disintegrated events of Ag and Br nuclei caused by 4.5 GeV per nucleon carbon projectile, we may conclude that the distribution of charged shower particles produced in forward hemisphere is flatter than the distribution in the backward hemisphere

  17. The ANC of 16O subthreshold states from 12C(6Li, d) reaction at energies near the barrier

    International Nuclear Information System (INIS)

    Adhikari, Sucheta; Basu, Chinmay

    2011-01-01

    The ANC of the 2 + (6.92 MeV) and 1 - (7.12 MeV) subthreshold states of 16 O have been extracted from the normalization of 12 C( 6 Li, d) angular distribution to a Finite Range Distorted Wave Born Approximation (FRDWBA) calculation. The theoretical analysis indicates a peripheral reaction and the extracted ANCs are not sensitive to the number of nodes in the bound state potential. The uncertainty from the entrance channel potential is minimized to 8% for the 6.92 and 11% for the 7.12 MeV state if the normalization is performed at the grazing angle. The uncertainty from the exit channel potential at the grazing angle is found to be 10% and 12% respectively for the 7.12 and 6.92 MeV states.

  18. Nitrogen-Doped Hollow Carbon Spheres with Embedded Co Nanoparticles as Active Non-Noble-Metal Electrocatalysts for the Oxygen Reduction Reaction

    Directory of Open Access Journals (Sweden)

    Ruohao Xing

    2018-02-01

    Full Text Available Transition metal (Fe, Co, Ni complexes on carbon nanomaterials are promising candidates as electrocatalysts towards the oxygen reduction reaction (ORR. In this paper, nitrogen-doped hollow carbon spheres with embedded Co nanoparticles were successfully prepared via a controllable synthesis strategy. The morphology characterization shows that the hollow carbon spheres possess an average diameter of ~150 nm with a narrow size distribution and a shell thickness of ~14.5 nm. The content of N doping ranges from 2.1 to 6.6 at.% depending on the calcination temperature from 900 to 1050 °C. Compared with commercial Pt/C, the Co-containing nitrogen-doped hollow carbon spheres prepared at 900 °C (CoNHCS-900 as an ORR electrocatalyst shows a half-wave potential shift of only ∆E1/2 = 55 mV, but a superior stability of about 90.2% maintenance after 20,000 s in the O2-saturated 0.1 M KOH at a rotating speed of 1600 rpm. This could be ascribed to the synergistic effects of N-containing moieties, Co-Nx species, and Co nanoparticles, which significantly increase the density of active sites and promote the charge transfer during the ORR process.

  19. The 12C + 12C: 1. Decay into high spin states of 23Mg, and 23Na. 2. Hauser-Feshbach analysis of the reaction mechanism

    International Nuclear Information System (INIS)

    Denhoefer, G.

    1980-01-01

    In this thesis different aspects of the reaction 12 C + 12 C were studied. The first part deals with high spin states in the mirror nucki 23 Na and 23 Mg experially with the states resonantly populated at Esub(cm) = 19.3 MeV. For the state at 9.80 MeV in 23 Na with (p,γ) angular correlation measurements a spin of 17/2 + and by Doppler form analysis a lifetime of (21 +- 9)fs was found. The probably analogous state at 9.61 MeV in 23 Mg decays both under p-emission to 22 Na and under γ-emission. Because of the p-decay probabilities to 3 + and 4 + of 22 Na, which were observed in (p,n) coincidence measurements, it has also the spin 17/2 + . In the second part of this thesis it was studied whether the reaction 12 C + 12 C at incident energies between 26 MeV and 42 MeV can be described using the statistical model. (orig./HSI) [de

  20. Study of removal of Direct Yellow 12 by cadmium oxide nanowires loaded on activated carbon

    Energy Technology Data Exchange (ETDEWEB)

    Ghaedi, Mehrorang, E-mail: m_ghaedi@mail.yu.ac.ir [Chemistry Department, Yasouj University Yasouj 75914-35 (Iran, Islamic Republic of); Sadeghian, Batuol [Chemistry Department, Yasouj University Yasouj 75914-35 (Iran, Islamic Republic of); Kokhdan, Syamak Nasiri, E-mail: syamak.nasiri@yahoo.com [Chemistry Department, Yasouj University Yasouj 75914-35 (Iran, Islamic Republic of); Pebdani, Arezou Amiri [Chemistry Department, Yasouj University Yasouj 75914-35 (Iran, Islamic Republic of); Sahraei, Reza; Daneshfar, Ali; Mihandoost, Asma [Department of Chemistry, University of Ilam, P.O. Box: 65315-516, Ilam (Iran, Islamic Republic of)

    2013-05-01

    In this research, cadmium oxide nanowires loaded on activated carbon (CdO-NW-AC) has been synthesized by a simple procedure and characterized by different techniques such as XRD, SEM and UV–vis spectrometry. This new adsorbent has been efficiently utilized for the removal of the Direct Yellow 12 (DY-12) from wastewater. To obtain maximum DY-12 removal efficiency, the influences of variables such as pH, DY-12 concentration, amount of CdO-NW-AC, contact time, and temperature have been examined and optimized in a batch method. Following the variable optimization, the experimental equilibrium data (at different concentration of DY-12) was fitted to conventional isotherm models such as Langmuir, Freundlich and Tempkin. The applicability of each method is based on the R{sup 2} and error analysis for each model. It was found that the experimental equilibrium data well fitted to the Langmuir isotherm model. The dependency of removal process to time and the experimental data follow second order kinetic model with involvement of intraparticle diffusion model. The negative value of Gibbs's free energy and positive value of adsorption enthalpy show the spontaneous and endothermic nature of adsorption process. - Graphical abstract: Typical FE-SEM image of the CdO nanowires. Highlights: ► Cadmium oxide nanowires loaded on activated carbon was utilized as an adsorbent. ► It was used for the removal of Direct Yellow 12 from aqueous solutions. ► The adsorption of Direct Yellow 12 on this adsorbent is endothermic in nature. ► The adsorption equilibrium data was well described by the Langmuir isotherm model.

  1. Free Br atom and free radical reactions in the radiolysis of 1,2 dibromoethane (DBE) in air free aqueous solutions

    International Nuclear Information System (INIS)

    Lal, Manohar

    1986-01-01

    G(Br - ) have been reported in the free radical degradation of 1,2 DBE in Ar - and N 2 O-saturated solutions. It is clear from the results that a small chain reaction occurs, t-butanol radical reacts with 1,2 DBE to give Br - . At pH 12.3, high (Br - ) are attributed to another chain reaction involving O - radical anion. Dose rate studies confirm the occurrence of chain reaction. (author). 5 refs

  2. Fabrication of carbonate apatite block based on internal dissolution-precipitation reaction of dicalcium phosphate and calcium carbonate.

    Science.gov (United States)

    Daitou, Fumikazu; Maruta, Michito; Kawachi, Giichiro; Tsuru, Kanji; Matsuya, Shigeki; Terada, Yoshihiro; Ishikawa, Kunio

    2010-05-01

    In this study, we investigated a novel method for fabrication of carbonate apatite block without ionic movement between precursor and solution by using precursor that includes all constituent ions of carbonate apatite. A powder mixture prepared from dicalcium phosphate anhydrous and calcite at appropriate Ca/P ratios (1.5, 1.67, and 1.8) was used as starting material. For preparation of specimens, the slurry made from the powder mixture and distilled water was packed in a split stainless steel mold and heat - treated, ranging from 60 degrees C to 100 degrees C up to 48 hours at 100% humidity. It appeared that carbonate apatite could be obtained above 70 degrees C and monophasic carbonate apatite could be obtained from the powder mixture at Ca/P ratio of 1.67. Carbonate content of the specimen was about 5-7%. Diametral tensile strength of the carbonate apatite blocks slightly decreased with increasing treatment temperature. The decrease in diametral tensile strength is thought to be related to the crystal size of the carbonate apatite formed.

  3. Influence of Micropore and Mesoporous in Activated Carbon Air-cathode Catalysts on Oxygen Reduction Reaction in Microbial Fuel Cells

    International Nuclear Information System (INIS)

    Liu, Yi; Li, Kexun; Ge, Baochao; Pu, Liangtao; Liu, Ziqi

    2016-01-01

    In this study, carbon samples with different micropore and mesoporous structures are prepared as air-cathode catalyst layer to explore the role of pore structure on oxygen reduction reaction. The results of linear sweep voltammetry and power density show that the commercially-produced activated carbon (CAC) has the best electrochemical performance, and carbon samples with only micropore or mesoporous show lower performance than CAC. Nitrogen adsorption-desorption isotherms analysis confirm that CAC has highest surface area (1616 m 2 g −1 ) and a certain amount of micropore and mesoporous. According to Tafel plot and rotating disk electrode, CAC behaves the highest kinetic activity and electron transfer number, leading to the improvement of oxygen reduction reaction. The air permeability test proves that mesoporous structure enhance oxygen permeation. Carbon materials are also analyzed by In situ Fourier Transform Infrared Spectroscopy and H 2 temperature programmed reduction, which indicate that micropore provide active sites for catalysis. In a word, micropore and mesoporous together would improve the electrochemical performance of carbon materials.

  4. Grafting methyl acrylic onto carbon fiber via Diels-Alder reaction for excellent mechanical and tribological properties of phenolic composites

    Science.gov (United States)

    Fei, Jie; Duan, Xiao; Luo, Lan; Zhang, Chao; Qi, Ying; Li, Hejun; Feng, Yongqiang; Huang, Jianfeng

    2018-03-01

    Carbon fibers (CFs) were grafted with methyl acrylic via Diels-Alder reaction at the different oil bath temperature effectively creating a carboxyl functionalized surface. The effect of grafting temperature on the surface morphology and functional groups of carbon fibers were investigated by FTIR, Raman spectroscopy, XPS and SEM respectively. The results showed that the optimal grafting temperature was 80 °C, and the relative surface coverage by carboxylic acid groups increased from an initial 5.16% up to 19.30% significantly improved the chemical activity without damaging the skin and core region of the carbon fibers. Mechanical property tests indicated that the shear and tensile strength of the sample with the grafting temperature of 80 °C (CFRP-3) increased obviously by 90.3% and 78.7%, respectively, compared with the pristine carbon fibers reinforced composite. Further, the sample CFRP-3 exhibited higher and more stable friction coefficient and improved wear resistance, while the wear rate decreased 52.7%, from 10.8 × 10-6 to 5.1 × 10-6 mm3/N m. The present work shows that grafting methyl acrylic via Diels-Alder reaction could be a highly efficient and facile method to functionalize carbon fibers for advanced composites.

  5. Highly Efficient Electrocatalysts for Oxygen Reduction Reaction Based on 1D Ternary Doped Porous Carbons Derived from Carbon Nanotube Directed Conjugated Microporous Polymers

    KAUST Repository

    He, Yafei; Gehrig, Dominik; Zhang, Fan; Lu, Chenbao; Zhang, Chao; Cai, Ming; Wang, Yuanyuan; Laquai, Fré dé ric; Zhuang, Xiaodong; Feng, Xinliang

    2016-01-01

    © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.One-dimensional (1D) porous materials have shown great potential for gas storage and separation, sensing, energy storage, and conversion. However, the controlled approach for preparation of 1D porous materials, especially porous organic materials, still remains a great challenge due to the poor dispersibility and solution processability of the porous materials. Here, carbon nanotube (CNT) templated 1D conjugated microporous polymers (CMPs) are prepared using a layer-by-layer method. As-prepared CMPs possess high specific surface areas of up to 623 m2 g-1 and exhibit strong electronic interactions between p-type CMPs and n-type CNTs. The CMPs are used as precursors to produce heteroatom-doped 1D porous carbons through direct pyrolysis. As-produced ternary heteroatom-doped (B/N/S) 1D porous carbons possess high specific surface areas of up to 750 m2 g-1, hierarchical porous structures, and excellent electrochemical-catalytic performance for oxygen reduction reaction. Both of the diffusion-limited current density (4.4 mA cm-2) and electron transfer number (n = 3.8) for three-layered 1D porous carbons are superior to those for random 1D porous carbon. These results demonstrate that layered and core-shell type 1D CMPs and related heteroatom-doped 1D porous carbons can be rationally designed and controlled prepared for high performance energy-related applications.

  6. Highly Efficient Electrocatalysts for Oxygen Reduction Reaction Based on 1D Ternary Doped Porous Carbons Derived from Carbon Nanotube Directed Conjugated Microporous Polymers

    KAUST Repository

    He, Yafei

    2016-10-11

    © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.One-dimensional (1D) porous materials have shown great potential for gas storage and separation, sensing, energy storage, and conversion. However, the controlled approach for preparation of 1D porous materials, especially porous organic materials, still remains a great challenge due to the poor dispersibility and solution processability of the porous materials. Here, carbon nanotube (CNT) templated 1D conjugated microporous polymers (CMPs) are prepared using a layer-by-layer method. As-prepared CMPs possess high specific surface areas of up to 623 m2 g-1 and exhibit strong electronic interactions between p-type CMPs and n-type CNTs. The CMPs are used as precursors to produce heteroatom-doped 1D porous carbons through direct pyrolysis. As-produced ternary heteroatom-doped (B/N/S) 1D porous carbons possess high specific surface areas of up to 750 m2 g-1, hierarchical porous structures, and excellent electrochemical-catalytic performance for oxygen reduction reaction. Both of the diffusion-limited current density (4.4 mA cm-2) and electron transfer number (n = 3.8) for three-layered 1D porous carbons are superior to those for random 1D porous carbon. These results demonstrate that layered and core-shell type 1D CMPs and related heteroatom-doped 1D porous carbons can be rationally designed and controlled prepared for high performance energy-related applications.

  7. Electrochemical investigations of Pu(IV)/Pu(III) redox reaction using graphene modified glassy carbon electrodes and a comparison to the performance of SWCNTs modified glassy carbon electrodes

    International Nuclear Information System (INIS)

    Gupta, Ruma; Gamare, Jayashree; Sharma, Manoj K.; Kamat, J.V.

    2016-01-01

    Highlights: • First report of aqueous electrochemistry of Plutonium on graphene modified electrode. • Graphene is best electrocatalytic material for Pu(IV)/Pu(III) redox couple among the reported modifiers viz. reduced graphene oxide (rGO) and SWCNT’s. • The electrochemical reversibility of Pu(IV)/Pu(III) redox couple improves significantly on graphene modified electrode compared to previously reported rGO & SWCNTs modified electrodes • Donnan interaction between plutonium species and graphene surface offers a possibility for designing a highly sensitive sensor for plutonium • Graphene modified electrode shows higher sensitivity for the determination of plutonium compared to glassy carbon and single walled carbon nanotube modified electrode - Abstract: The work reported in this paper demonstrates for the first time that graphene modified glassy carbon electrode (Gr/GC) show remarkable electrocatalysis towards Pu(IV)/Pu(III) redox reaction and the results were compared with that of single-walled carbon nanotubes modified GC (SWCNTs/GC) and glassy carbon (GC) electrodes. Graphene catalyzes the exchange of current of the Pu(IV)/Pu(III) couple by reducing both the anodic and cathodic overpotentials. The Gr/GC electrode shows higher peak currents (i p ) and smaller peak potential separation (ΔE p ) values than the SWCNTs/GC and GC electrodes. The heterogeneous electron transfer rate constants (k s ), charge transfer coefficients (α) and the diffusion coefficients (D) involved in the electrocatalytic redox reaction were determined. Our observations show that graphene is best electrocatalytic material among both the SWCNTs and GC to study Pu(IV)/Pu(III) redox reaction.

  8. Scattering of alpha particles from /sup 12/C and the /sup 12/C(. cap alpha. ,. gamma. )/sup 16/O stellar reaction rate

    Energy Technology Data Exchange (ETDEWEB)

    Plaga, R.; Becker, H.W.; Redder, A.; Rolfs, C.; Trautvetter, H.P.; Langanke, K.

    1987-04-06

    The elastic scattering of alpha particles from /sup 12/C has been investigated for 35 angles in the range theta/sub lab/ = 22/sup 0/ to 163/sup 0/ and for 51 energies at E/sub ..cap alpha../ = 1.0 to 6.6 MeV. The extracted phase shifts for l=0 to 6 partial waves have been parametrized in terms of the multilevel R-matrix formalism. Information on the deduced parameters of states in /sup 16/O is reported. The data reveal reduced ..cap alpha..-particle widths for the 6.92 and 7.12 MeV subthreshold states consistent with recent work. The implications for the stellar reaction rate of /sup 12/C(..cap alpha..,..gamma..)/sup 16/O are discussed.

  9. Energy loss of /sup 12/C projectiles in different carbon modifications

    International Nuclear Information System (INIS)

    Baek, W.Y.; Both, G.H.; Gassen, D.; Neuwirth, W.; Zielinski, M.

    1987-01-01

    The stopping cross sections of the three carbon modifications diamond, graphite, and glassy carbon are investigated for carbon projectiles of intermediate velocity. The inverted Doppler-shift attenuation method was used as the experimental technique, and it enabled us to measure the ratios of the three stopping cross sections precisely over a wide energy range. For velocities between 3 and 4 times Bohr's velocity the stopping cross sections of graphite and glassy carbon are found to be 1.036 and 1.072 times larger than that of diamond, respectively. These differences are attributed to binding effects. To understand these effects, we have evaluated the mean ionization potentials utilizing the local-plasma approximation for the inner-shell electrons and the dielectric response function for the valence electrons. The theoretical ratios calculated by inserting these potentials into the Bethe-Bloch stopping-power formula agree well with our experimental results. Furthermore, we have obtained a value of 53.3 +- 4.1 fs for the lifetime of the first excited state of the /sup 12/C nucleus

  10. Magnetic Carbon Supported Palladium Nanoparticles: An Efficient and Sustainable Catalyst for Hydrogenation Reactions

    Science.gov (United States)

    Magnetic carbon supported Pd catalyst has been synthesized via in situ generation of nanoferrites and incorporation of carbon from renewable cellulose via calcination; the catalyst can be used for the hydrogenation of alkenes and reduction of aryl nitro compounds.

  11. Study of some direct reactions at 00 in 18O+26Mg and 18O+12C systems

    International Nuclear Information System (INIS)

    Payet, J.

    1984-01-01

    Direct transfer reactions induced by a 18 O beam on 12 C and 26 Mg targets, have been studied at the MP tandem (Orsay) with an experimental set up giving the possibility to have angular distributions up to 0 0 . Transfer reactions to discrete levels were analysed in the D.W.B.A. framework. This analysis confirms the interest as a spectroscopic tool of this 0 0 measurements. The ( 18 O, 16 O) and ( 18 O, 20 Ne) reactions were observed up to 40 MeV excitation energy. A diffractionnal model, including the one step direct transfer hypothesis, gives a qualitative agreement with the angular distributions and the energy spectra. A parametrization of a specific small angles development of the transfer amplitudes does not give good results with physical values for the parameters. 32 refs [fr

  12. Experimental and modeling study of high performance direct carbon solid oxide fuel cell with in situ catalytic steam-carbon gasification reaction

    Science.gov (United States)

    Xu, Haoran; Chen, Bin; Zhang, Houcheng; Tan, Peng; Yang, Guangming; Irvine, John T. S.; Ni, Meng

    2018-04-01

    In this paper, 2D models for direct carbon solid oxide fuel cells (DC-SOFCs) with in situ catalytic steam-carbon gasification reaction are developed. The simulation results are found to be in good agreement with experimental data. The performance of DC-SOFCs with and without catalyst are compared at different operating potential, anode inlet gas flow rate and operating temperature. It is found that adding suitable catalyst can significantly speed up the in situ steam-carbon gasification reaction and improve the performance of DC-SOFC with H2O as gasification agent. The potential of syngas and electricity co-generation from the fuel cell is also evaluated, where the composition of H2 and CO in syngas can be adjusted by controlling the anode inlet gas flow rate. In addition, the performance DC-SOFCs and the percentage of fuel in the outlet gas are both increased with increasing operating temperature. At a reduced temperature (below 800 °C), good performance of DC-SOFC can still be obtained with in-situ catalytic carbon gasification by steam. The results of this study form a solid foundation to understand the important effect of catalyst and related operating conditions on H2O-assisted DC-SOFCs.

  13. Carbonation of steel slag for CO2 sequestration: Leaching of products and reaction mechanisms

    NARCIS (Netherlands)

    Huijgen, W.J.J.; Comans, R.N.J.

    2006-01-01

    Carbonation of industrial alkaline residues can be used as a CO2 sequestration technology to reduce carbon dioxide emissions. In this study, steel slag samples were carbonated to a varying extent. Leaching experiments and geochemical modeling were used to identify solubility-controlling processes of

  14. Accelerated carbonation using municipal solid waste incinerator bottom ash and cold-rolling wastewater: Performance evaluation and reaction kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Chang, E-E [Department of Biochemistry, Taipei Medical University, 250 Wu-Hsing Street, Taipei City, Taiwan 110, Taiwan, ROC (China); Pan, Shu-Yuan [Graduate Institute of Environmental Engineering, National Taiwan University, 71 Chou-Shan Rd., Taipei City, Taiwan 10673, Taiwan, ROC (China); Yang, Liuhanzi [School of Environment, Tsinghua University, Haidin District, Beijing 100084 (China); Chen, Yi-Hung [Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, 1, Sec. 3, Zhongxiao E. Rd., Taipei City, Taiwan 10608, Taiwan, ROC (China); Kim, Hyunook [Department of Energy and Environmental System Engineering, University of Seoul (Korea, Republic of); Chiang, Pen-Chi, E-mail: pcchiang@ntu.edu.tw [Graduate Institute of Environmental Engineering, National Taiwan University, 71 Chou-Shan Rd., Taipei City, Taiwan 10673, Taiwan, ROC (China)

    2015-09-15

    Highlights: • Carbonation was performed using CO{sub 2}, wastewater and bottom ash in a slurry reactor. • A maximum capture capacity of 102 g CO{sub 2} per kg BA was achieved at mild conditions. • A maximum carbonation conversion of MSWI-BA was predicted to be 95% by RSM. • The CO{sub 2} emission from Bali incinerator could be expected to reduce by 6480 ton/y. • The process energy consumption per ton CO{sub 2} captured was estimated to be 180 kW h. - Abstract: Accelerated carbonation of alkaline wastes including municipal solid waste incinerator bottom ash (MSWI-BA) and the cold-rolling wastewater (CRW) was investigated for carbon dioxide (CO{sub 2}) fixation under different operating conditions, i.e., reaction time, CO{sub 2} concentration, liquid-to-solid ratio, particle size, and CO{sub 2} flow rate. The MSWI-BA before and after carbonation process were analyzed by the thermogravimetry and differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy equipped with energy dispersive X-ray spectroscopy. The MSWI-BA exhibits a high carbonation conversion of 90.7%, corresponding to a CO{sub 2} fixation capacity of 102 g per kg of ash. Meanwhile, the carbonation kinetics was evaluated by the shrinking core model. In addition, the effect of different operating parameters on carbonation conversion of MSWI-BA was statistically evaluated by response surface methodology (RSM) using experimental data to predict the maximum carbonation conversion. Furthermore, the amount of CO{sub 2} reduction and energy consumption for operating the proposed process in refuse incinerator were estimated. Capsule abstract: CO{sub 2} fixation process by alkaline wastes including bottom ash and cold-rolling wastewater was developed, which should be a viable method due to high conversion.

  15. Carboxyl functionalization of carbon fibers via aryl diazonium reaction in molten urea to enhance interfacial shear strength

    Science.gov (United States)

    Wang, Yuwei; Meng, Linghui; Fan, Liquan; Wu, Guangshun; Ma, Lichun; Zhao, Min; Huang, Yudong

    2016-01-01

    Using molten urea as the solvent, carbon fibers were functionalized with carboxylic acid groups via aryl diazonium reaction in 15 min to improve their interfacial bonding with epoxy resin. The surface functionalization was quantified by X-ray photoelectron spectroscopy, which showed that the relative surface coverage of carboxylic acid groups increased from an initial percentage of 3.17-10.41%. Mechanical property test results indicated that the aryl diazonium reaction in this paper could improve the interfacial shear strength by 66%. Meanwhile, the technique did not adopt any pre-oxidation step to produce functional groups prior to grafting and was shown to maintain the tensile strength of the fibers. This methodology provided a rapid, facile and economically viable route to produce covalently functionalized carbon fibers in large quantities with an eco-friendly method.

  16. Observation of monopole strength in the 12C(e,e'p0)11B reaction

    International Nuclear Information System (INIS)

    Calarco, J.R.; Arruda-Neto, J.; Griffioen, K.A.; Hanna, S.S.; Hoffmann, D.H.H.; Neyer, B.; Rand, R.E.; Wienhard, K.; Yearian, M.R.

    1984-01-01

    The location of the giant monopole resonance and, therefore, the compressibility is unknown in light nuclei. The forward-backward (e, e'p) angular correlation asymmetry from 12 C has been measured and found to be very sensitive to monopole strength in the giant dipole resonance region. Similar reactions will, thus, provide a sensitive tool in the search for monopole strength in light nuclei. (orig.)

  17. The reaction p12C→ηX from Tp=800 MeV to Tp=1500 MeV

    International Nuclear Information System (INIS)

    Chiavassa, E.; Dellacasa, G.; De Marco, N.; De Oliveira Martins, O.; Gallio, M.; Guaita, P.; Musso, A.; Piccotti, A.; Scomparin, E.; Vercellin, E.

    1998-01-01

    The reaction p 12 C→nX has been studied, at several proton kinetic energies ranging from 800 MeV to 1500 MeV, at the proton synchrotron Saturne at Saclay. The measured doubly differential cross-sections are presented and discussed in the framework of a simple theoretical model. The model fails in describing the deepest subthreshold data while the above-threshold data are fairly well reproduced. (orig.)

  18. Ground-state correlations in 12C and the mechanism of the (e,e'p) reaction

    International Nuclear Information System (INIS)

    Steenhoven, G. van der.

    1987-01-01

    In this thesis the results of an investigation into two aspects of the mechanism of the quasi-elastic (e,e'p) reaction: the interaction between the incident electron and the bound proton and the residual nucleus (final-state interaction (FSI)), are presented and used in the extraction of nuclear-structure information from (e,e'p) measurements on 12 C. The experiments were carried out at NIKHEF-K with a high-resolution spectrometer. Two kinds of experiments have been performed on 12 C. The first was aimed at obtaining accurate momentum distributions for various final states in 11 B. Some special measurements were carried out in order to vary the parameters influencing the FSI. The role of coupled-channels effects in the 12 C(e,e'p) 11 Be reaction is discussed. It is discussed whether some of the weak transitions observed in this reaction, can be associated with knockout from normally unoccupied shell-model orbitals. The second experiment on 12 C was devoted to the e-p coupling. These measurements were supplemented with data taken on 6 Li. The latter measurement allowed for measuring simultaneously knockout from the relatively dense 4 He core and the relatively dilute deuteron. In this way the density dependence of the e-p coupling in the nucleus could be studied. The results of these experiments have been compared to various models that take into account the effect of the nuclear medium upon the e-p coupling. The possible role of charge-exchange and meson-exchange currents in the interpretation of these experiments is also considered. A brief survey of the formalism of the quasi-elastic (e,e'p) reaction is also presented. (author). 196 refs.; 53 figs.; 21 tabs

  19. Unveiling the uncatalyzed reaction of alkynes with 1,2-dipoles for the room temperature synthesis of cyclobutenes.

    Science.gov (United States)

    Alcaide, Benito; Almendros, Pedro; Fernández, Israel; Lázaro-Milla, Carlos

    2015-02-25

    2-(Pyridinium-1-yl)-1,1-bis(triflyl)ethanides have been used as 1,2-dipole precursors in a metal-free direct [2+2] cycloaddition reaction of alkynes. Starting from stable zwitterionic pyridinium salts, the electron deficient olefin 1,1-bis(trifluoromethylsulfonyl)ethene is generated in situ and immediately reacted at room temperature with an alkyne to afford substituted cyclobutenes. Remarkably, this mild and facile uncatalyzed protocol requires neither irradiation nor heating.

  20. Study of fragmentation cross-sections for 12C+12C reaction at 95 MeV/u and 400 MeV/u for hadron-therapy

    International Nuclear Information System (INIS)

    Juliani, Didier

    2013-01-01

    The hadron-therapy is a radiotherapy method using ions (carbon ions here) instead of the more conventional X-rays for cancer treatment. Deep radioresistant tumour areas, as brain carcinoma for example, can be treated thanks to the specific dose deposition at the end of the ion path. This is an additional method to older classic ones (surgery, X-rays, chemotherapy). Two hadron-therapy centres for treatment and research are planned in France from 2018 (ARCHADE) in order to benefit from the newest progress and to keep improving this method. Carbon ions energy loss in the matter follows the Bethe-Bloch law. The maximum of energy depth is located in a limited area called 'Bragg peak'. By adjusting the beam position and energy, the whole volume of the tumor can be irradiated. Nevertheless, nuclear reactions of carbon ion in tissues generate the production of lighter fragments (H, He, Li etc.) that deposit their energy beyond the Bragg peak. Models implemented in hadron-therapy simulation codes (FLUKA, GEANT4 etc.) cannot reproduce angular distributions of the lighter fragments and energy distributions at the same time. These poor estimations affect the treatment planning systems accuracy that are clinically used. Indeed, a bad estimation of fragmentation process induces a bias in the dose calculation concerning healthy cells beyond the Bragg peak. In order to better constraint models, two experiments based on fragmentation cross-sections measurements have been performed. The first one in may 2011 with a beam at 95 MeV/u (GANIL) in collaboration with the LPC Caen and the second one in august 2011 with a beam at 400 MeV/u (GSI) with the FIRST collaboration. E600 experiment is devoted to the study of carbon ions fragmentation at 95 MeV/u in several thin targets (Au, C, , Ti etc.) corresponding to the basic building blocks of human body. Five telescopes are designed for the fragments detection. Each one is a three-stage detector (2 silicon detectors and one CsI scintillator

  1. A combined high-temperature experimental and theoretical kinetic study of the reaction of dimethyl carbonate with OH radicals

    KAUST Repository

    Khaled, Fathi; Giri, Binod; Szőri, Milá n; Mai, Tam V.-T.; Huynh, Lam K.; Farooq, Aamir

    2017-01-01

    The reaction kinetics of dimethyl carbonate (DMC) and OH radicals were investigated behind reflected shock waves over the temperature range of 872-1295 K and at pressures near 1.5 atm. Reaction progress was monitored by detecting OH radicals at 306.69 nm using a UV laser absorption technique. The rate coefficients for the reaction of DMC with OH radicals were extracted using a detailed kinetic model developed by Glaude et al. (Proc. Combust. Inst. 2005, 30(1), 1111-1118). The experimental rate coefficients can be expressed in Arrhenius form as: kexpt'l = 5.15 × 10(13) exp(-2710.2/T) cm(3) mol(-1) s(-1). To explore the detailed chemistry of the DMC + OH reaction system, theoretical kinetic analyses were performed using high-level ab initio and master equation/Rice-Ramsperger-Kassel-Marcus (ME/RRKM) calculations. Geometry optimization and frequency calculations were carried out at the second-order Møller-Plesset (MP2) perturbation level of theory using Dunning's augmented correlation consistent-polarized valence double-ζ basis set (aug-cc-pVDZ). The energy was extrapolated to the complete basis set using single point calculations performed at the CCSD(T)/cc-pVXZ (where X = D, T) level of theory. For comparison purposes, additional ab initio calculations were also carried out using composite methods such as CBS-QB3, CBS-APNO, G3 and G4. Our calculations revealed that the H-abstraction reaction of DMC by OH radicals proceeds via an addition elimination mechanism in an overall exothermic process, eventually forming dimethyl carbonate radicals and H2O. Theoretical rate coefficients were found to be in excellent agreement with those determined experimentally. Rate coefficients for the DMC + OH reaction were combined with literature rate coefficients of four straight chain methyl ester + OH reactions to extract site-specific rates of H-abstraction from methyl esters by OH radicals.

  2. Kerma factors and reaction cross sections for n + 12C between 15 and 18 MeV

    International Nuclear Information System (INIS)

    Tornow, W.; Chen, Z.M.; Baird, K.; Walter, R.L.

    1988-01-01

    Differential elastic and inelastic (4.44 MeV) neutron scattering cross sections from 12 C are presented at 15.6, 16.8 and 17.3 MeV. The existing 18.2 MeV differential cross-section data were combined with newly measured analysing power data to parametrise neutron scattering at this energy. The 12 C recoil kerma factors were calculated and reaction cross sections were obtained from a phase-shift analysis and coupled channel analyses in the 15.6-18.2 MeV energy range. (author)

  3. Kerma factors and reaction cross sections for n + /sup 12/C between 15 and 18 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Tornow, W.; Chen, Z.M.; Baird, K.; Walter, R.L.

    1988-07-01

    Differential elastic and inelastic (4.44 MeV) neutron scattering cross sections from /sup 12/C are presented at 15.6, 16.8 and 17.3 MeV. The existing 18.2 MeV differential cross-section data were combined with newly measured analysing power data to parametrise neutron scattering at this energy. The /sup 12/C recoil kerma factors were calculated and reaction cross sections were obtained from a phase-shift analysis and coupled channel analyses in the 15.6-18.2 MeV energy range.

  4. Study of the excited levels of 11C and 12C by the analysis of protons induced reactions

    International Nuclear Information System (INIS)

    Rihet, Y.

    1984-07-01

    The present work is a study of 11 and 12 C excited states by reactions of non polarised protons on 10 B and 11 B. R-matrix analysis of the 10 B excitation curves in the range E p = 0 to 8 MeV was used to establish parameters of 41 levels in 11 C. Isobaric multiplets of T = 1/2 and T = 3/2 states in A = 11 nuclei are deduced. Analysis of 11 B excitation curves in the E p = 0.5 to 7.4 MeV range led to parameter values of 60 levels in 12 C. T = 1 states in A = 12 isobaric nuclei are discussed [fr

  5. Synthesis of graphitic carbon nitride by reaction of melamine and uric acid

    International Nuclear Information System (INIS)

    Dante, Roberto C.; Martin-Ramos, Pablo; Correa-Guimaraes, Adriana; Martin-Gil, Jesus

    2011-01-01

    Highlights: → Graphitic carbon nitrides by CVD of melamine and uric acid on alumina. → The building blocks of carbon nitrides are heptazine nuclei. → Composite particles with alumina core and carbon nitride coating. - Abstract: Graphitic carbon nitrides were synthesized starting from melamine and uric acid. Uric acid was chosen because it thermally decomposes, and reacts with melamine by condensation at temperatures in the range of 400-600 deg. C. The reagents were mixed with alumina and subsequently the samples were treated in an oven under nitrogen flux. Alumina favored the deposition of the graphitic carbon nitrides layers on the exposed surface. This method can be assimilated to an in situ chemical vapor deposition (CVD). Infrared (IR) spectra, as well as X-ray diffraction (XRD) patterns, are in accordance with the formation of a graphitic carbon nitride with a structure based on heptazine blocks. These carbon nitrides exhibit poor crystallinity and a nanometric texture, as shown by transmission electron microscopy (TEM) analysis. The thermal degradation of the graphitic carbon nitride occurs through cyano group formation, and involves the bridging tertiary nitrogen and the bonded carbon, which belongs to the heptazine ring, causing the ring opening and the consequent network destruction as inferred by connecting the IR and X-ray photoelectron spectroscopy (XPS) results. This seems to be an easy and promising route to synthesize graphitic carbon nitrides. Our final material is a composite made of an alumina core covered by carbon nitride layers.

  6. Magnetic substate populations of product nuclei in the /sup 11/B(d,p)/sup 12/B reaction

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, M; Ochi, S; Minamisono, T; Mizobuchi, A; Sugimoto, K [Osaka Univ., Toyonaka (Japan). Lab. of Nuclear Studies

    1976-05-31

    Magnetic substate populations of product nuclei in the /sup 11/B(d,p)/sup 12/B reaction have been measured in an energy range Esub(d) = 1.3-3.0 MeV at recoil angles of thetasub(R) = 55/sup 0/, 45/sup 0/ and 27/sup 0/-37/sup 0/. A static magnetic field (3 kG) was applied normal to the reaction plane to keep the nuclear orientation. Quadrupole effects on the implanted /sup 12/B in Ta were utilized to perturb the Zeeman splitting. NMR transitions were induced, and detected by the asymmetry change in the ..beta..-decay of /sup 12/B. From this information, the magnetic substate populations were determined, for the unique assignment of which the sign of the quadrupole interaction had to be known. For this purpose, a p-..gamma.. angular correlation was measured, which determined the alignment of the first excited state of /sup 12/B. A comparison of the present result with theoretical predictions is given, together with the resultant information about j-mixings in the /sup 12/B states.

  7. Role of adsorbed surfactant in the reaction of aryl diazonium salts with single-walled carbon nanotubes.

    Science.gov (United States)

    Hilmer, Andrew J; McNicholas, Thomas P; Lin, Shangchao; Zhang, Jingqing; Wang, Qing Hua; Mendenhall, Jonathan D; Song, Changsik; Heller, Daniel A; Barone, Paul W; Blankschtein, Daniel; Strano, Michael S

    2012-01-17

    Because covalent chemistry can diminish the optical and electronic properties of single-walled carbon nanotubes (SWCNTs), there is significant interest in developing methods of controllably functionalizing the nanotube sidewall. To date, most attempts at obtaining such control have focused on reaction stoichiometry or strength of oxidative treatment. Here, we examine the role of surfactants in the chemical modification of single-walled carbon nanotubes with aryl diazonium salts. The adsorbed surfactant layer is shown to affect the diazonium derivatization of carbon nanotubes in several ways, including electrostatic attraction or repulsion, steric exclusion, and direct chemical modification of the diazonium reactant. Electrostatic effects are most pronounced in the cases of anionic sodium dodecyl sulfate and cationic cetyltrimethylammonium bromide, where differences in surfactant charge can significantly affect the ability of the diazonium ion to access the SWCNT surface. For bile salt surfactants, with the exception of sodium cholate, we find that the surfactant wraps tightly enough such that exclusion effects are dominant. Here, sodium taurocholate exhibits almost no reactivity under the explored reaction conditions, while for sodium deoxycholate and sodium taurodeoxycholate, we show that the greatest extent of reaction is observed among a small population of nanotube species, with diameters between 0.88 and 0.92 nm. The anomalous reaction of nanotubes in this diameter range seems to imply that the surfactant is less effective at coating these species, resulting in a reduced surface coverage on the nanotube. Contrary to the other bile salts studied, sodium cholate enables high selectivity toward metallic species and small band gap semiconductors, which is attributed to surfactant-diazonium coupling to form highly reactive diazoesters. Further, it is found that the rigidity of anionic surfactants can significantly influence the ability of the surfactant layer to

  8. Durability of carbon-supported manganese oxide nanoparticles for the oxygen reduction reaction (ORR) in alkaline medium

    Czech Academy of Sciences Publication Activity Database

    Roche, I.; Chainet, E.; Chatenet, M.; Vondrák, Jiří

    2008-01-01

    Roč. 38, č. 9 (2008), s. 1195-1201 ISSN 0021-891X R&D Projects: GA AV ČR KJB4813302; GA ČR GA104/02/0731 Grant - others:CNRS(FR) 18105 Institutional research plan: CEZ:AV0Z40320502 Keywords : oxygen reduction reaction * rotating ring-disc electrode * carbon-supported manganese oxide Subject RIV: CA - Inorganic Chemistry Impact factor: 1.540, year: 2008

  9. Unified mechanism of alkali and alkaline earth catalyzed gasification reactions of carbon by CO2 and H2O

    Science.gov (United States)

    Chen, S.G.; Yang, R.T.

    1997-01-01

    From molecular orbital calculations, a unified mechanism is proposed for the gasification reactions of graphite by CO2 and H2O, both uncatalyzed and catalyzed by alkali and alkaline earth catalysts. In this mechanism, there are two types of oxygen intermediates that are bonded to the active edge carbon atoms: an in-plane semiquinone type, Cf(O), and an off-plane oxygen bonded to two saturated carbon atoms that are adjacent to the semiquinone species, C(O)Cf(O). The rate-limiting step is the decomposition of these intermediates by breaking the C-C bonds that are connected to Cf(O). A new rate equation is derived for the uncatalyzed reactions, and that for the catalyzed reactions is readily available from the proposed mechanism. The proposed mechanism can account for several unresolved experimental observations: TPD and TK (transient kinetics) desorption results of the catalyzed systems, the similar activation energies for the uncatalyzed and catalyzed reactions, and the relative activities of the alkali and alkaline earth elements. The net charge of the edge carbon active site is substantially changed by gaining electron density from the alkali or alkaline earth element (by forming C-O-M, where M stands for metal). The relative catalytic activities of these elements can be correlated with their abilities of donating electrons and changing the net charge of the edge carbon atom. As shown previously (Chen, S. G.; Yang, R. T. J. Catal. 1993, 141, 102), only clusters of the alkali compounds are active. This derives from the ability of the clusters to dissociate CO2 and H2O to form O atoms and the mobility of the dissociated O atoms facilitated by the clusters.

  10. The Reduction Reaction of Dissolved Oxygen in Water by Hydrazine over Platinum Catalyst Supported on Activated Carbon Fiber

    Energy Technology Data Exchange (ETDEWEB)

    Park, K.K.; Moon, J.S. [Korea Electric Power Research Institute, Taejon (Korea)

    1999-07-01

    The reduction reaction of dissolved oxygen (DO) by hydrazine was investigated on activated carbon fiber (ACF) and Pt/ACF catalysts using a batch reactor with an external circulating loop. The ACF itself showed catalytic activity and this was further improved by supporting platinum on ACF. The catalytic role platinum is ascribed to its acceleration of hydrazine decomposition, based on electric potential and current measurements as well as the kinetic study. (author). 15 refs., 13 figs.

  11. Indirect measurement of the 15N(p,α)12C reaction cross section through the THM

    International Nuclear Information System (INIS)

    Romano, S.; La Cognata, M.; Spitaleri, C.; Cherubini, S.; Gulino, M.; Lamia, L.; Musumarra, A.; Tribble, R.; Trache, C.L.; Fu, C.

    2005-01-01

    Among the reactions of the stellar CNO cycle, the 15 N(p,α) 12 C plays a crucial role. In particular its reaction rate is important for understanding the CNOI escape towards CNOII. Thus it is important to study its bare nucleus cross section at the energies typical of such astrophysical environments, i.e. few tens of keV. At these energies such a measurement is hard to perform in a direct way because of the electron screening effect as pointed out for several cases. A possibility is then given by indirect methods and in particular the Trojan Horse Method (THM) has been applied in this case. The preliminary validity test for the study of 15 N(p,α) 12 C via the 15 N(d,α 12 C)n three body reaction is reported in this work. A 15 N beam was provided by the cyclotron at Texas A and M University with energy 60 MeV/c and delivered onto a CD 2 target. A ΔE/E telescope (PSD + ionization chamber) and a pair of PSD's were mounted in a coplanar geometry. Coincidences between the detectors were considered and the 15 N-p quasi-free contribution to the overall three-body cross-section was selected. Data analysis and preliminary results will be discussed and compared with direct data. (author)

  12. Three-dimensional iron, nitrogen-doped carbon foams as efficient electrocatalysts for oxygen reduction reaction in alkaline solution

    International Nuclear Information System (INIS)

    Ma, Yanjiao; Wang, Hui; Feng, Hanqing; Ji, Shan; Mao, Xuefeng; Wang, Rongfang

    2014-01-01

    Graphical abstract: Three-dimentional Fe, N-doped carbon foams prepared by two steps exhibited comparable catalytic activity for oxygen reduction reaction to commercial Pt/C due to the unique structure and the synergistic effect of Fe and N atoms. - Highlights: • Three-dimensional Fe, N-doped carbon foam (3D-CF) were prepared. • 3D-CF exhibits comparable catalytic activity to Pt/C for oxygen reduction reaction. • The enhanced activity of 3D-CF results of its unique structure. - Abstract: Three-dimensional (3D) Fe, N-doped carbon foams (3D-CF) as efficient cathode catalysts for the oxygen reduction reaction (ORR) in alkaline solution are reported. The 3D-CF exhibit interconnected hierarchical pore structure. In addition, Fe, N-doped carbon without porous strucuture (Fe-N-C) and 3D N-doped carbon without Fe (3D-CF’) are prepared to verify the electrocatalytic activity of 3D-CF. The electrocatalytic performance of as-prepared 3D-CF for ORR shows that the onset potential on 3D-CF electrode positively shifts about 41 mV than those of 3D-CF’ and Fe-N-C respectively. In addition, the onset potential on 3D-CF electrode for ORR is about 27 mV more negative than that on commercial Pt/C electrode. 3D-CF also show better methanol tolerance and durability than commercial Pt/C catalyst. These results show that to synthesize 3D hierarchical pores with high specific surface area is an efficient way to improve the ORR performance

  13. Generalized eczematous reaction after fractional carbon dioxide laser therapy for tattoo allergy.

    Science.gov (United States)

    Meesters, Arne A; De Rie, Menno A; Wolkerstorfer, Albert

    2016-12-01

    Allergic tattoo reactions form a therapeutically difficult entity. Treatment with conventional quality-switched lasers does not completely remove the allergenic particles and may lead to generalized hypersensitivity reactions. Recently, ablative fractional laser therapy was introduced as a treatment for allergic tattoo removal. We present two cases of allergic reactions to red tattoo ink treated with 10,600-nm fractional CO 2 laser. At the end of treatment, almost complete removal of red ink accompanied by a significant reduction of symptoms was observed in the first patient, whereas the second patient developed an acute generalized eczematous reaction after five treatments. These findings confirm that ablative fractional laser therapy is capable of significant removal of tattoo ink in an allergic tattoo reaction. However, it implies a risk of generalized hypersensitivity reactions. To our knowledge, this is the first case of a generalized hypersensitivity reaction following treatment of tattoo allergy with the fractional CO 2 laser.

  14. Interfacial Reaction Dependent Performance of Hollow Carbon Nanosphere – Sulfur Composite as a Cathode for Li-S Battery

    International Nuclear Information System (INIS)

    Zheng, Jianming; Yan, Pengfei; Gu, Meng; Wagner, Michael J.; Hays, Kevin A.; Chen, Junzheng; Li, Xiaohong; Wang, Chongmin; Zhang, Ji-Guang; Liu, Jun; Xiao, Jie

    2015-01-01

    Lithium-sulfur (Li-S) battery is a promising energy storage system due to its high energy density, cost effectiveness, and environmental friendliness of sulfur. However, there are still a number of technical challenges, such as low Coulombic efficiency and poor long-term cycle life, impeding the commercialization of Li-S battery. The electrochemical performance of Li-S battery is closely related with the interfacial reactions occurring between hosting substrate and active sulfur species, which are poorly conducting at fully oxidized and reduced states. Here, we correlate the relationship between the performance and interfacial reactions in the Li-S battery system, using a hollow carbon nanosphere (HCNS) with highly graphitic character as hosting substrate for sulfur. With an appropriate amount of sulfur loading, HCNS/S composite exhibits excellent electrochemical performance because of the fast interfacial reactions between HCNS and the polysulfides. However, further increase of sulfur loading leads to increased formation of highly resistive insoluble reaction products (Li 2 S 2 /Li 2 S), which limits the reversibility of the interfacial reactions and results in poor electrochemical performances. These findings demonstrate the importance of the interfacial reaction reversibility in the whole electrode system on achieving high capacity and long cycle life of sulfur cathode for Li-S batteries.

  15. Interfacial Reaction Dependent Performance of Hollow Carbon Nanosphere – Sulfur Composite as a Cathode for Li-S Battery

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Jianming; Yan, Pengfei; Gu, Meng [Pacific Northwest National Laboratory, Richland, WA (United States); Wagner, Michael J.; Hays, Kevin A. [The George Washington University, Washington, DC (United States); Chen, Junzheng; Li, Xiaohong; Wang, Chongmin; Zhang, Ji-Guang; Liu, Jun; Xiao, Jie, E-mail: jie.xiao@pnnl.gov [Pacific Northwest National Laboratory, Richland, WA (United States)

    2015-05-26

    Lithium-sulfur (Li-S) battery is a promising energy storage system due to its high energy density, cost effectiveness, and environmental friendliness of sulfur. However, there are still a number of technical challenges, such as low Coulombic efficiency and poor long-term cycle life, impeding the commercialization of Li-S battery. The electrochemical performance of Li-S battery is closely related with the interfacial reactions occurring between hosting substrate and active sulfur species, which are poorly conducting at fully oxidized and reduced states. Here, we correlate the relationship between the performance and interfacial reactions in the Li-S battery system, using a hollow carbon nanosphere (HCNS) with highly graphitic character as hosting substrate for sulfur. With an appropriate amount of sulfur loading, HCNS/S composite exhibits excellent electrochemical performance because of the fast interfacial reactions between HCNS and the polysulfides. However, further increase of sulfur loading leads to increased formation of highly resistive insoluble reaction products (Li{sub 2}S{sub 2}/Li{sub 2}S), which limits the reversibility of the interfacial reactions and results in poor electrochemical performances. These findings demonstrate the importance of the interfacial reaction reversibility in the whole electrode system on achieving high capacity and long cycle life of sulfur cathode for Li-S batteries.

  16. Effect of carbon content on microstructure and mechanical properties of hot-rolled low carbon 12Cr-Ni stainless steel

    International Nuclear Information System (INIS)

    Zheng, H.; Ye, X.N.; Li, J.D.; Jiang, L.Z.; Liu, Z.Y.; Wang, G.D.; Wang, B.S.

    2010-01-01

    Research highlights: → Hot-rolled ultra low carbon martensite is characterized by dislocation cells substructure. → The formation of dislocation cells is attributed to high Ms and low interstitial atoms content. → Hot-rolled ultra low carbon 12Cr-Ni stainless steel has excellent impact toughness. → Delta ferrite deteriorates the impact toughness of hot-rolled 12Cr-Ni stainless steel. - Abstract: 12Cr-Ni stainless steels containing different carbon contents from 0.004 wt.% to 0.034 wt.% were hot-rolled and air-cooled. Their corresponding microstructures were observed with optical microscope and transmission electron microscope, and the Vickers hardness, tensile and impact tests were also carried out. It was found that the martensitic morphology was significantly influenced by carbon content. The as-received ultra low carbon martensite in the steel containing 0.004 wt.% C is characterized by dislocation cells substructure. The formation of dislocation cells is attributed to high martensite finishing point (above 400 deg. C) and low interstitial atoms content. On the other hand, the martensite in the steel containing 0.034 wt.% C consists mainly of typical martensite laths because of low martensite finishing point and high interstitial atoms content which hinder dislocation motion. Furthermore, carbon content has an evident effect on the mechanical properties of 12Cr-Ni steels. The hardness and strength of the as-received steels increase with an increase in carbon content, but their elongation and impact toughness decrease with the carbon content. The steel containing 0.004 wt.% C has excellent impact toughness due to the ultra low carbon content in the martensite composed of dislocation cells.

  17. Carbon budget over 12 years in a production crop under temperate climate

    Science.gov (United States)

    Buysse, Pauline; Bodson, Bernard; Debacq, Alain; De Ligne, Anne; Heinesch, Bernard; Manise, Tanguy; Moureaux, Christine; Aubinet, Marc

    2017-04-01

    Carbon dioxide (CO2) exchanges between crops and the atmosphere are influenced by both climatic and crop management drivers. The investigated crop, situated at the Lonzée Terrestrial Observatory (LTO, candidate ICOS site) in Belgium and managed for more than 70 years using conventional farming practices, was monitored over three complete sugar beet (or maize)/winter wheat/potato/winter wheat rotation cycles from 2004 to 2016. Continuous eddy-covariance measurements and regular biomass samplings were performed in order to obtain the daily and seasonal Net Ecosystem Exchange (NEE), Gross Primary Productivity, Total Ecosystem Respiration, Net Primary Productivity, and Net Biome Production (NBP). Meteorological data and crop management practices were also recorded. The main objectives were to analyze the CO2 flux responses to climatic drivers and to establish the C budget of the cropland. Crop type significantly influenced the measured CO2 fluxes. In addition to crop season duration, which had an obvious impact on cumulated NEE values for each crop type, the CO2 flux response to photosynthetic photon flux density, vapor pressure deficit and temperature differed between crop types, while no significant response to soil water content was observed in any of them. Besides, a significant positive relationship between crop residue amount and ecosystem respiration was observed. Over the 12 years, NEE was negative (-4.34 ± 0.21 kg C m-2) but NBP was positive (1.05 ± 0.30 kg C m-2), i.e. as soon as all lateral carbon fluxes - dominated by carbon exportation - are included in the budget, the site behaves as a carbon source. Intercrops were seen to play a major role in the carbon budget, being mostly due to the long time period it represented (59 % of the 12 year time period). An in-depth analysis of intercrop periods and, more specifically, growing cover crops (mustard in the case of our study), is developed in a companion poster (ref. abstract EGU2017-12216, session SSS9

  18. Thermonuclear reaction listing

    International Nuclear Information System (INIS)

    Fukai, Yuzo

    1993-01-01

    The following 10 elements, including T, are well known as nuclear fusion fuels: p, D, T, 3 He, 4 He, 6 Li, 7 Li, 9 Be, 10 B, 11 B, ( 12 C, 13 C), where 12 C and 13 C are considered only in the calculation of Q value. Accordingly the number of the thermonuclear reactions is 55, and 78, if including carbon elements. The reactions have some branches. For the branches having two and three reaction products, the reaction products, Q value and threshold energy are calculated by using a computer. We have investigated those of the branches having more than three products from the papers of Ajzenberg-Selove and so on. And also, by the same papers, we check whether the above mentioned branch has been observed or not. The results are as follows: (I) the number of reactions which have Q 0 branches only with γ ray production, and Q 0 and neutron production is 36(17), and (IV) that of reactions whose branch with Q > 0 does not produce neutrons is 9(3). The value in the parentheses shows the number of the case of the carbon elements. For 55 thermonuclear reactions induced by lighter nuclides than 11 B, the reaction products, the values of Q and threshold energy, and the papers with reaction cross section data are presented in the tables. (author)

  19. Graphene-oxide-supported CuAl and CoAl layered double hydroxides as enhanced catalysts for carbon-carbon coupling via Ullmann reaction

    Science.gov (United States)

    Ahmed, Nesreen S.; Menzel, Robert; Wang, Yifan; Garcia-Gallastegui, Ainara; Bawaked, Salem M.; Obaid, Abdullah Y.; Basahel, Sulaiman N.; Mokhtar, Mohamed

    2017-02-01

    Two efficient catalyst based on CuAl and CoAl layered double hydroxides (LDHs) supported on graphene oxide (GO) for the carbon-carbon coupling (Classic Ullmann Homocoupling Reaction) are reported. The pure and hybrid materials were synthesised by direct precipitation of the LDH nanoparticles onto GO, followed by a chemical, structural and physical characterisation by electron microscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), surface area measurements and X-ray photoelectron spectroscopy (XPS). The GO-supported and unsupported CuAl-LDH and CoAl-LDH hybrids were tested over the Classic Ullman Homocoupling Reaction of iodobenzene. In the current study CuAl- and CoAl-LDHs have shown excellent yields (91% and 98%, respectively) at very short reaction times (25 min). GO provides a light-weight, charge complementary and two-dimensional material that interacts effectively with the 2D LDHs, in turn enhancing the stability of LDH. After 5 re-use cycles, the catalytic activity of the LDH/GO hybrid is up to 2 times higher than for the unsupported LDH.

  20. Measurement of the total reaction cross section for interactions between heavy ions (application to the system 12C+12C at 112MeV)

    International Nuclear Information System (INIS)

    Cherkaoui-Tadili, R.

    1982-01-01

    The total reaction cross-section σsub(R) for interactions between heavy ions is predicted to decrease rapidly with the energy of the incident projectile over the energy range 10 MeV/A - 100 MeV/A. We present here an experimental met σsub(R) to test the model based predictions. The method consists in counting the number of all incoming projectiles and the number of out going projectiles that did not interact with the target. The difference between these two numbers corresponds to the number of particles that reacted with the target nuclei and is therefore proportional to σsub(R). Values of σsub(R) have been measured for the system 12 C + 12 C at two incident energies of 112 MeV and 996 MeV. The results of 1444 +- 70 (112 MeV) and 994 +- 50 (996 MeV) show a total reaction cross-section decreasing with energy as predicted from the Glauber model and optical model fits to elastic scattering [fr

  1. Critical role of the 12C(αγ) 16O reaction is stellar evolution and synthesis

    International Nuclear Information System (INIS)

    Weaver, T.A.

    1993-01-01

    The extreme sensitivity of stellar evolution and nucleosynthesis to the rate of the 12 C(α,γ) 16 O reaction will be reviewed in the context of models of the complete evolution of 12 to 40 solar mass stars from their birth on the main-sequence to their death in supernova explosions. The nucleosynthesis resulting from integrating the yields of these models over plausible initial stellar mass distributions is found to be in excellent agreement with the observed solar abundances of virtually all intermediate mass isotopes if, and only if, the 12 C(α,γ) 16 O Tate falls within a narrow subset of its currently experimentally allowed range. Factor of 2 to 3 variations in this rate lead to up to a factor of 100 variations in major isotopic production ratios. The importance of further experiments to accurately measure this rate (which is apparently dominated by the contributions of subthreshold resonances) will be stressed

  2. Effect of alpha states in the 16O+12C scattering and in the 12C +α → 16O capture reaction of astrophysical interest

    International Nuclear Information System (INIS)

    Morais, M.C.; Lichtenthaele, R.; Arazi, A.; Hojman, D.; Cardona, M.A.; Fimiani, L.; Carnelli, P.F.; Marti, G.V.; Pacheco, A.J.; Martinez Heimann, D.; Negri, A.E.; Capurro, O.A.; Niello, Fernandez; Montero, P.

    2011-01-01

    Full text: The 16 O+ 12 C elastic scattering was investigated considering the effect of exchange of an alpha particle between projectile and target leading to the same nuclei of the entrance channel (elastic transfer). Angular distributions were analyzed in an energy range from 8.55 MeV to 56.57 MeV in the center of mass frame. The Coulomb barrier is around 11MeV for this system. Measurements of angular distributions of elastic and inelastic transfer reactions to states of the 16 O in the 16 O+ 12 C system were performed at the TANDAR Laboratory in Buenos Aires, using an 16 O beam of E lab = 46; 26 MeV. The transfer angular distributions were analyzed by DWBA using the computer code FRESCO. Those measurements provided the spectroscopic factors of 12 C + α → 16 O for the ground state and for J π = 2 + and J π = 1 - 16 O excited states, both just below the α-threshold at 7.16 MeV. The Asymptotic Normalization Coefficient (ANC) for the J π = 2 + state was obtained (1.05 ±0,13(10 5 fm -1/2 )) and used to calculate the reduced width of this state, with this value a R-matrix calculation was performed to determine the astrophysical S-factor in energies around the Gamow peak, S(E2)=37keVb. (author)

  3. Electron transfer. 93. Further reactions of transition-metal-center oxidants with vitamin B12s (Cob(I)alamin)

    International Nuclear Information System (INIS)

    Pillai, G.C.; Ghosh, S.K.; Gould, E.S.

    1988-01-01

    Vitamin B 12s (cob(I)alamin) reduces europium(III), titanium(IV) (TiO(C 2 O 4 ) 2 2- ), and uranium(VI) in aqueous solution. These oxidants undergo one-electron changes, leading in each case to the cobalt product cob(II)alamin (B 12r ). The reduction of Eu 3+ , which is inhibited by TES buffer, but not by glycine, is outer sphere. Its limiting specific rate (1 x 10 2 M -1 s -1 ), incorporated in the Marcus treatment, yields a B 12s ,B 12r self-exchange rate of 10 4.8±0.5 M -1 s -1 . Reductions of TiO(C 2 O 4 ) 2 2- are accelerated by H + and by acetic acid. Kinetic patterns suggest three competing reaction paths involving varying degrees of protonation of the Ti(IV) center or its association with acetic acid. The very rapid reduction of U(VI) (k = 4 x 10 6 M -1 s -1 ) yields U(V) in several buffering media, even when B 12s is taken in excess. The much slower conversion of U(V) to U(IV), although thermodynamically favored, appears to be retarded by the extensive reorganization of the coordination sphere of oxo-bound U(V) that must accompany its acceptance of an additional electron. The observed specific rate for the B 12s -U(VI) reaction is in reasonable agreement, in the framework of the Marcus formalism, with reported values of the formal potential and the self-exchange rate for U(V,VI). 37 references, 4 tables

  4. Oxygen reduction activity of carbon fibers cathode, and application for current generation from the NAD+ and NADH recycling reaction

    Directory of Open Access Journals (Sweden)

    H. Maeda

    2012-03-01

    Full Text Available Carbon fibers treated at 700 oC for 10 min were found to have O2 reduction activity when being used as a cathode. The special type of partition combined with both cationic and anionic exchange membranes was applied between anode cell and cathode cell in order to use a highly acidic solution such as 0.5 M H2SO4 as an electrolyte of the cathode cell for increasing the efficiency of O2 reduction activity. The current generation from NAD+ and NADH recycling system combined with D-gluconolactone production from 500 mg of D-glucose was performed by applying only carbon fibers for both anode and cathode. The total current volume obtained was 81.4 mAh during the reaction for 10 h, and the current efficiency was 93%. One gram of carbon fibers was pressed with Nafion paste on a piece of carbon paper(area : 50 mm×50mm with heating to prepare the cathode, and this construct was combined with conventional fuel cell. The power density was 3.6 mW/cm2, and the total power volume was calculated to be 90 mW per 1 g of carbon fibers.

  5. The chemistry of subcritical water reactions of a hardwood derived lignin and lignin model compounds with nitrogen, hydrogen, carbon monoxide and carbon dioxide

    Science.gov (United States)

    Hill Bembenic, Meredith A.

    collected solids from the CO reactions appeared to be the most reacted (i.e., the most changed from the unreacted lignin) according to solid state 13C-NMR analysis, and the widest variety of products (methoxy-substituted phenolic compounds) were obtained when using CO according to GC/MS analysis. Therefore, reactions with CO were completed that varied the initial reaction pressure (300, 500 and 800 psi) in order to elucidate the effects of CO pressure. Similar conversion (≈54--58%) and DCM-soluble liquid product yields (≈53--62%) were obtained for the different pressure reactions, but the reactions with an initial pressure of 500 psi had the greatest change in aromaticity from the unreacted lignin. Additional reactions between Organosolv lignin and H2O with CO (initial pressure of 500 psi) were conducted where the reaction time was varied (15, 30 and 60 min.) to determine the effect of reaction time. Longer reaction time (60 min.) appeared to inhibit conversion to low molecular weight compounds (i.e., conversion and DCM-soluble yields were lower at ≈53% and ≈28%, respectively). Solid state 13C-NMR of collected residues also showed that there are losses in carbons representative of both guaiacyl and syringyl components as reaction time increases, which may indicate that methoxy groups are being cleaved or the products are reacting with each other (i.e., repolymerization) to form high molecular weight compounds as reaction time is increased. The role of H2O and the gases during the baseline reactions and the expanded CO reactions is not intuitive based on the results, so reactions with lignin model compounds (i.e., aromatic aldehydes represented by vanillin and syringaldehyde, aromatic ketones represented by acetovanillone and acetosyringone, and aromatic ethers represented by dibenzyl ether and 2-phenethyl phenyl ether) were completed to study this. From these results, the suggested reaction pathway of Organosolv lignin reactions in subcritical H2O with and without

  6. Reactions of nitriles with iodonium salt of bis(1,2-dicarbollyl)cobalt

    International Nuclear Information System (INIS)

    Knyazev, S.P.; Kirin, V.N.; Chernyshev, E.A.

    1996-01-01

    Interaction of nitriles with iodonium salt bis(1,2-dicarbollyl)cobalt, resulting in the 8,8'-disubstituted derivatives, is studied. Interaction of nitrile group with iodonium fragment is accompanied by B-I bond discontinuity and by formation of B-N bond with subsequent formation of amino alcohol, which regroups into amide. 3 refs

  7. Low-energy angular distributions for the 12C(e,π+)e' reaction

    International Nuclear Information System (INIS)

    Sealock, R.M.; Caplan, H.S.; Lolos, G.J.; Haxton, W.C.

    1981-01-01

    Angular distributions for near threshold electroproduction of positive pions from 12 C are reported and compared to theory. These data provide tests of recently developed second-order optical potentials and of the nuclear response to electroproduction in the giant resonance region

  8. Study of the Nuclear Transparency in $\\alpha$ + A Reactions at Energies $\\geq$ 12 GeV/nucleon

    CERN Multimedia

    2002-01-01

    The question about transparency is crucial for heavy ion reaction studies. If the transparency is low at 10-15 GeV per nucleon then very large baryon densities can be achieved in this energy range, maybe enough to produce quark-gluon plasma in U+U collisions. We propose to measure, event by event, pseudo-rapidity and multiplicity distributions of singly charged relativistic particles (@b~$>$~0.7) globally and in selected regions of rapidity as well as multiplicities of recoiling protons (30-400~Me charged nuclear fragments. These studies will explore general features of @a+A reactions at energies @$>$~12~GeV/nucleon. The main goal of the experiment is to measure the transparency of nuclear matter in this energy range. The detector will be nuclear emulsion.

  9. Ξ-P Scattering and STOPPED-Ξ-12C Reaction

    Science.gov (United States)

    Ahn, J. K.; Aoki, S.; Chung, K. S.; Chung, M. S.; En'yo, H.; Fukuda, T.; Funahashi, H.; Goto, Y.; Higashi, A.; Ieiri, M.; Iijima, T.; Iinuma, M.; Imai, K.; Itow, Y.; Lee, J. M.; Makino, S.; Masaike, A.; Matsuda, Y.; Matsuyama, Y.; Mihara, S.; Nagoshi, C.; Nomura, I.; Park, I. S.; Saito, N.; Sekimoto, M.; Shin, Y. M.; Sim, K. S.; Susukita, R.; Takashima, R.; Takeutchi, F.; Tlustý, P.; Weibe, S.; Yokkaichi, S.; Yoshida, K.; Yoshida, M.; Yoshida, T.; Yamashita, S.

    2000-09-01

    We report upper limits on the cross sections for the Ξ-p elastic and conversion processes based on the observation of one Ξ-p elastic scattering events with an invisible Λ decay. The cross section for the Ξ-p elastic scattering is, for simplicity, assumming an isotropic angular distribution, found to be 40 mb at 90% confidence level, whereas that for the Ξ-p → ΛΛ reaction is 11 mb at 90% confidence level. While the results on the elastic cross section give no stringent constraint on theoretical estimates, the upper limit on the conversion process suggests that the estimate of the RGM-F model prediction could be ruled out. We also report some preliminary results on the obervation of the stopped-Ξ- hyperon-nucleus interaction with respect to hypernuclear production and existence of doubly-strange H-dibaryon.

  10. Oxygen reduction reaction on a highly-alloyed Pt-Ni supported carbon electrocatalyst in acid solution

    CSIR Research Space (South Africa)

    Zheng, H

    2010-08-31

    Full Text Available Alloyed electrocatalysts such as PtNi/C[1-2], PtCo/C[3], PtCr/C[4], PtFe/C [5-6], and non-alloyed Pt-TiO2/C were reportedly investigated for methanol tolerance during Oxygen reduction reaction (ORR). The high methanol tolerance...

  11. Studies on the heterogeneous electron transport and oxygen reduction reaction at metal (Co, Fe) octabutylsulphonylphthalocyanines supported on multi-walled carbon nanotube modified graphite electrode

    CSIR Research Space (South Africa)

    Mamuru, SA

    2010-09-01

    Full Text Available Heterogeneous electron transfer dynamics and oxygen reduction reaction (ORR) activities using octabutylsulphonylphthalocyanine complexes of iron (FeOBSPc) and cobalt (CoOBSPc) supported on multi-walled carbon nanotube (MWCNT) platforms have been...

  12. Iron (II) tetrakis(diaquaplatinum) octacarboxyphthalocyanine supported on multi-walled carbon nanotubes as effective electrocatalyst for oxygen reduction reaction in alkaline medium

    CSIR Research Space (South Africa)

    Mamuru, SA

    2010-11-01

    Full Text Available Oxygen reduction reaction (ORR) in alkaline medium at iron (II) tetrakis (diaquaplatinum) octacarboxyphthalocyanine (PtFeOCPc) catalyst supported on multi-walled carbon nanotubes (MWCNTs) has been described. The ORR followed the direct 4-electron...

  13. Enantioselective organocatalyzed Oxa-Michael-Aldol cascade reactions: Construction of chiral 4H-chromenes with a trifluoromethylated tetrasubstituted carbon stereocenter

    KAUST Repository

    Zhang, Jing; Ajitha, Manjaly John; He, Lin; Liu, Kai; Dai, Bin; Huang, Kuo-Wei

    2015-01-01

    The first organocatalytic asymmetric synthesis of 4H-chromenes bearing a trifluoromethylated tetrasubstituted carbon center is presented. Chiral secondary amines promote the oxa-Michael-aldol cascade reaction between alkynals and 2

  14. Process for carrying out a chemical reaction with ionic liquid and carbon dioxide under pressure

    NARCIS (Netherlands)

    Kroon, M.C.; Shariati, A.; Florusse, L.J.; Peters, C.J.; Van Spronsen, J.; Witkamp, G.J.; Sheldon, R.A.; Gutkowski, K.I.

    2006-01-01

    The invention is directed to a process for carrying out a chemical reaction in an ionic liquid as solvent and CO2 as cosolvent, in which process reactants are reacted in a homogeneous phase at selected pressure and temperature to generate a reaction product at least containing an end-product of the

  15. Femtosecond laser control of chemical reaction of carbon monoxide and hydrogen

    CSIR Research Space (South Africa)

    Du Plessis, A

    2010-09-01

    Full Text Available Femtosecond laser control of chemical reactions is made possible through the use of pulse-shaping techniques coupled to a learning algorithm feedback loop – teaching the laser pulse to control the chemical reaction. This can result in controllable...

  16. Femtosecond laser induced and controlled chemical reaction of carbon monoxide and hydrogen

    CSIR Research Space (South Africa)

    Du Plessis, A

    2011-07-01

    Full Text Available Results from experiments aimed at bimolecular chemical reaction control of CO and H2 at room temperature and pressure, without any catalyst, using shaped femtosecond laser pulses are presented. A stable reaction product (CO2) was measured after...

  17. Improving the electrocatalytic performance of carbon nanotubes for VO"2"+/VO_2"+ redox reaction by KOH activation

    International Nuclear Information System (INIS)

    Dai, Lei; Jiang, Yingqiao; Meng, Wei; Zhou, Huizhu; Wang, Ling; He, Zhangxing

    2017-01-01

    Highlights: • KOH-activated carbon nanotubes (CNTs) was investigated as superior catalyst for VO"2"+/VO_2"+ redox reaction for vanadium redox flow battery (VRFB) for the first time. • KOH activation for CNTs can result in the chemical etching of surface and improved wettability, accelerating the mass transfer of vanadium ions. • KOH activation can introduce many oxygen-containing groups as active sites on the surface of CNTs. • KOH-activated CNTs as positive catalyst could increase the comprehensive energy storage performance of VRFB. - Abstract: In this paper, carbon nanotubes (CNTs) was activated by KOH treatment at high temperature and investigated as catalyst for VO"2"+/VO_2"+ redox reaction for vanadium redox flow battery (VRFB). X-ray photoelectron spectroscopy results suggest that the oxygen-containing groups can be introduced on CNTs by KOH activation. The mass transfer of vanadium ions can be accelerated by chemical etching by KOH activation and improved wettability due to the introduction of hydrophilic groups. The electrochemical properties of VO"2"+/VO_2"+ redox reaction can be enhanced by introduced oxygen-containing groups as active sites. The sample treated at 900 °C with KOH/CNTs mass ratio of 3:1 (CNTs-3) exhibits the highest electrocatalytic activity for VO"2"+/VO_2"+ redox reaction. The cell using CNTs-3 as positive catalyst demonstrates the smallest electrochemical polarization, the highest capacity and efficiency among the samples. Using KOH-activated CNTs-3 can increase the average energy efficiency of the cell by 4.4%. This work suggests that KOH-activated CNTs is a low-cost, efficient and promising catalyst for VO"2"+/VO_2"+ redox reaction for VRFB system.

  18. Reaction mechanisms in 12C(γ,pp) near 200 MeV

    Science.gov (United States)

    Hackett, E. D.; McDonald, W. J.; Opper, A. K.; Quraan, M. A.; Rodning, N. L.; Rozon, F. M.; Feldman, G.; Kolb, N. R.; Pywell, R. E.; Skopik, D. M.; Tiller, D. E.; Vogt, J. M.; Korkmaz, E.; O'rielly, G. V.

    1996-03-01

    Inclusive 12C(γ,pp) cross sections have been measured with tagged photons in the range Eγ=187-227 MeV using the Saskatchewan-Alberta Large Acceptance Detector (SALAD). The large angular acceptance allowed the measurement of noncoplanar pp emission. The cross sections were compared to a Monte Carlo intranuclear cascade calculation. Agreement was reasonable for the shapes of the cross sections but the calculated total cross section was 3.9 times larger than the data.

  19. Regioselective syntheses of 1,2-benzothiazines by rhodium-catalyzed annulation reactions.

    Science.gov (United States)

    Cheng, Ying; Bolm, Carsten

    2015-10-12

    Rhodium-catalyzed directed carbene insertions into aromatic CH bonds of S-aryl sulfoximines lead to intermediates, which upon dehydration provide 1,2-benzothiazines in excellent yields. The domino-type process is regioselective and shows a high functional-group tolerance. It is scalable, and the only by-products are dinitrogen and water. Three illustrative transformations underscore the synthetic value of the products. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Quasielastic C-12(e,e ' p) reaction at high momentum transfer

    NARCIS (Netherlands)

    Morrison, JH; Baghaei, H; Bertozzi, W; Gilad, S; Glickman, J; Hyde-Wright, CE; Kalantar-Nayestanaki, N; Lourie, RW; Penn, S; Ulmer, PE; Weinstein, LB; Cottman, BH; Ghedira, L; Winhold, EJ; Calarco, J.R.; Wise, J; Boberg, P; Chang, CC; Zhang, D; Aniol, K; Epstein, MB; Margaziotis, DJ; Finn, JM; Perdrisat, C; Punjabi, P.

    We measured the C-12(e,e'p) cross section as a function of missing energy in parallel kinematics for (q,omega)=(970 MeV/c, 330 MeV) and (990 MeV/c, 475 MeV). At omega=475 MeV, at the maximum of the quasielastic peak, there is a large continuum (E-m>50 MeV) cross section extending out to the deepest

  1. Graphite Carbon-Supported Mo2C Nanocomposites by a Single-Step Solid State Reaction for Electrochemical Oxygen Reduction.

    Science.gov (United States)

    Huang, K; Bi, K; Liang, C; Lin, S; Wang, W J; Yang, T Z; Liu, J; Zhang, R; Fan, D Y; Wang, Y G; Lei, M

    2015-01-01

    Novel graphite-molybdenum carbide nanocomposites (G-Mo2C) are synthesized by a typical solid state reaction with melamine and MoO3 as precursors under inert atmosphere. The characterization results indicate that G-Mo2C composites are composed of high crystallization and purity of Mo2C and few layers of graphite carbon. Mo2C nanoparticles with sizes ranging from 5 to 50 nm are uniformly supported by surrounding graphite layers. It is believed that Mo atom resulting from the reduction of MoO3 is beneficial to the immobilization of graphite carbon. Moreover, the electrocatalytic performances of G-Mo2C for ORR in alkaline medium are investigated by cyclic voltammetry (CV), rotating disk electrode (RDE) and chronoamperometry test with 3M methanol. The results show that G-Mo2C has a considerable catalytic activity and superior methanol tolerance performance for the oxygen reduction reaction (ORR) benefiting from the chemical interaction between the carbide nanoparticles and graphite carbon.

  2. WC Nanocrystals Grown on Vertically Aligned Carbon Nanotubes: An Efficient and Stable Electrocatalyst for Hydrogen Evolution Reaction.

    Science.gov (United States)

    Fan, Xiujun; Zhou, Haiqing; Guo, Xia

    2015-05-26

    Single nanocrystalline tungsten carbide (WC) was first synthesized on the tips of vertically aligned carbon nanotubes (VA-CNTs) with a hot filament chemical vapor deposition (HF-CVD) method through the directly reaction of tungsten metal with carbon source. The VA-CNTs with preservation of vertical structure integrity and alignment play an important role to support the nanocrystalline WC growth. With the high crystallinity, small size, and uniform distribution of WC particles on the carbon support, the formed WC-CNTs material exhibited an excellent catalytic activity for hydrogen evolution reaction (HER), giving a η10 (the overpotential for driving a current of 10 mA cm(-2)) of 145 mV, onset potential of 15 mV, exchange current density@ 300 mV of 117.6 mV and Tafel slope values of 72 mV dec(-1) in acid solution, and η10 of 137 mV, onset potential of 16 mV, exchange current density@ 300 mV of 33.1 mV and Tafel slope values of 106 mV dec(-1) in alkaline media, respectively. Electrochemical stability test further confirms the long-term operation of the catalyst in both acidic and alkaline media.

  3. Efficient Cycloaddition Reaction of Carbon Dioxide with Epoxide by Rhodamine Based Catalyst Under 1 atm Pressure

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Qing; Luo, Huadong; Cao, Di; Zhang, Haibo; Wang, Wenjing; Zhou, Xiaohai [Wuhan University, Wuhan (China)

    2012-06-15

    Rhodamine B (RhB) and rhodamine 6G (Rh6G) were employed as catalysts for the synthesis of cyclic carbonate from carbon dioxide and epoxide. It turned out that the catalytic activity of Rh6G was nearly 29 times higher than that of RhB at 1 atm pressure, 90 .deg. C. Furthermore, the catalytic efficiency of RhB and Rh6G was greatly enhanced with triethylamine as co-catalyst. Under the optimized conditions, the best isolated yield (93%) of cyclic carbonate was achieved without organic solvent and metal component

  4. Study of Reaction Mechanism in the Interaction 86 MeV/A $^{12}$C with Heavy Targets

    CERN Multimedia

    2002-01-01

    Using the thin target-thin catcher techniques and the off-line analysis of the activities induced in the irradiated foils by means of singles and coincidences spectra recorded with Ge(Li) @g-rays and Si X-rays detectors, we will measure: 1) The target fragment mass and charge distribution from the interact 2) 86 MeV/A |1|2C with silver, tin and gold. 3) The target fragment average kinetic energy. 4) The target fragment angular and differential kinetic energy distributions. These measurements should allow us to better understand the heavy ion reaction mechanisms at intermediate energy.

  5. Carbon Incorporation and Anion Dynamics as Synergistic Drivers for Ultrafast Diffusion in Superionic LiCB11H12 and NaCB11H12

    Energy Technology Data Exchange (ETDEWEB)

    Dimitrievska, Mirjana [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Shea, Patrick [Lawrence Livermore National Laboratory; Kweon, Kyoung E. [Lawrence Livermore National Laboratory; Bercx, Marnik [University of Antwerp; Varley, Joel B. [Lawrence Livermore National Laboratory; Tang, Wan Si [National Institute of Standards and Technology; University of Maryland; Skripov, Alexander V. [Ural Division of the Russian Academy of Sciences; Stavila, Vitalie [Sandia National Laboratories; Udovic, Terrence J. [National Institute of Standards and Technology; Wood, Brandon C. [Lawrence Livermore National Laboratory

    2018-02-02

    The disordered phases of LiCB11H12 and NaCB11H12 possess superb superionic conductivities that make them suitable as solid electrolytes. In these materials, cation diffusion correlates with high orientational mobilities of the CB11H12- anions; however, the precise relationship has yet to be demonstrated. In this work, ab initio molecular dynamics and quasielastic neutron scattering are combined to probe anion reorientations and their mechanistic connection to cation mobility over a range of timescales and temperatures. It is found that anions do not rotate freely, but rather transition rapidly between orientations defined by the cation sublattice symmetry. The symmetry-breaking carbon atom in CB11H12- also plays a critical role by perturbing the energy landscape along the instantaneous orientation of the anion dipole, which couples fluctuations in the cation probability density directly to the anion motion. Anion reorientation rates exceed 3 x 1010 s-1, suggesting the underlying energy landscape fluctuates dynamically on diffusion-relevant timescales. Furthermore, carbon is found to modify the orientational preferences of the anions and aid rotational mobility, creating additional symmetry incompatibilities that inhibit ordering. The results suggest that synergy between the anion reorientational dynamics and the carbon-modified cation-anion interaction accounts for the higher ionic conductivity in CB11H12- salts compared with B12H122-.

  6. Carbon coated Li4Ti5O12 nanorods as superior anode material for high rate lithium ion batteries

    International Nuclear Information System (INIS)

    Luo, Hongjun; Shen, Laifa; Rui, Kun; Li, Hongsen; Zhang, Xiaogang

    2013-01-01

    Highlights: •A novel approach has been developed to fabricate 1D Li 4 Ti 5 O 12 /C nanorods by a wet-chemical route. •Carbon coating layer effectively restrict the particle growth and enhance electronic conductivity. •The Li 4 Ti 5 O 12 /C nanorods exhibit remarkable rate capability and long cycle life. -- Abstract: We describe a novel approach for the synthesis of carbon coated Li 4 Ti 5 O 12 (Li 4 Ti 5 O 12 /C) nanorods for high rate lithium ion batteries. The carbon coated TiO 2 nanotubes using the glucose as carbon source are first synthesized by hydrothermal treatment. The commercial anatase TiO 2 powder is immersed in KOH sulotion and subsequently transforms into Li 4 Ti 5 O 12 /C in LiOH solution under hydrothermal condition. Field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, nitrogen adsorption/desorption and Raman spectra are performed to characterize their morphologies and structures. Compared with the pristine Li 4 Ti 5 O 12 , one-dimensional (1D) Li 4 Ti 5 O 12 /C nanostructures show much better rate capability and cycling stability. The 1D Li 4 Ti 5 O 12 /C architectures effectively restrict the particle growth and enhance their electronic conductivity, enabling fast ion and electron transport

  7. Neutron spectra and level density parameters from 16O + 12C fusion reaction

    International Nuclear Information System (INIS)

    Kasagi, J.; Remington, B.; Galonsky, A.; Haas, F.; Racca, R.; Prosser, F.W.

    1985-01-01

    Residues following 16 O + 12 C fusion were identified by their characteristic γ-rays. For several transitions in 23 Mg, 25 Mg, and 26 Al coincident neutron spectra were measured at six angles. Through use of the evaporation code CASCADE, comparisons were made of these spectra with predictions of the statistical model at five 16 O projectile energies between 43.2 and 56.0 MeV. The results require an excitation energy dependence for the effective radius parameter r 0 which determines the spin cutoff factor

  8. Radioprotection shielding for neutrons induced by the reaction (2H (40 MeV, 12C

    Directory of Open Access Journals (Sweden)

    Fadil M.

    2017-01-01

    Full Text Available In the framework of design studies for SPIRAL2, the simulation of the neutron flux generated by 40 MeV deuterons on a thick 12C target was performed and compared to experimental data. The calculation of the dose rate of these neutrons allowed to compare four materials being considered for radioprotection shielding: barites, gypsum, ordinary concrete and heavy concrete. The simulated map of the neutron dose rate in the production building shows a very high dose rate around the neutron source and in the environment of some of the accelerator equipment.

  9. Reaction mechanisms in 12C(γ,pp) near 200 MeV

    International Nuclear Information System (INIS)

    Hackett, E.D.; McDonald, W.J.; Opper, A.K.; Quraan, M.A.; Rodning, N.L.; Rozon, F.M.; Feldman, G.; Kolb, N.R.; Pywell, R.E.; Skopik, D.M.; Tiller, D.E.; Vogt, J.M.; Korkmaz, E.; ORielly, G.V.

    1996-01-01

    Inclusive 12 C(γ,pp) cross sections have been measured with tagged photons in the range E γ =187 endash 227 MeV using the Saskatchewan-Alberta Large Acceptance Detector (SALAD). The large angular acceptance allowed the measurement of noncoplanar pp emission. The cross sections were compared to a Monte Carlo intranuclear cascade calculation. Agreement was reasonable for the shapes of the cross sections but the calculated total cross section was 3.9 times larger than the data. copyright 1996 The American Physical Society

  10. Functionalization of Carbon Nanotubes via Electrophilic Substitution Reaction in Polyphosphoric Acid

    National Research Council Canada - National Science Library

    Baek, Jong-Beom

    2006-01-01

    .... Furthermore, on the basis of all supportive evidences, this work provides one of the most efficient methods to directly and uniformly grafting the surfaces of carbon nanotubes (CNT) and nanofibers (CNF...

  11. Study of the preparation of Cu-TiC composites by reaction of soluble Ti and ball-milled carbon coating TiC

    Science.gov (United States)

    Xu, Xuexia; Li, Wenbin; Wang, Yong; Dong, Guozhen; Jing, Shangqian; Wang, Qing; Feng, Yanting; Fan, Xiaoliang; Ding, Haimin

    2018-06-01

    In this work, Cu-TiC composites have been successfully prepared by reaction of soluble Ti and carbon coating TiC. Firstly, the ball milling of graphite and TiC mixtures is used to obtain the carbon coating TiC which has fine size and improved reaction activity. After adding the ball milled carbon coating TiC into Cu-Ti melts, the soluble Ti will easily react with the carbon coating to form TiC. This process will also improve the wettability between Cu melts and TiC core. As a result, besides the TiC prepared by reaction of soluble Ti and carbon coating, the ball milled TiC will also be brought into the melts. Some of these ball-milled TiC particles will go on being coated by the formed TiC from the reaction of Ti and the coating carbon and left behind in the composites. However, most of TiC core will be further reacted with the excessive Ti and be transformed into the newly formed TiC with different stoichiometry. The results indicate that it is a feasible method to synthesize TiC in Cu melts by reaction of soluble Ti and ball-milled carbon coating TiC.

  12. Improved capacity and rate capability of Ru-doped and carbon-coated Li4Ti5O12 anode material

    International Nuclear Information System (INIS)

    Lin, Chih-Yuan; Jhan, Yi-Ruei; Duh, Jenq-Gong

    2011-01-01

    Highlights: → By using a simple one-step solid-state reactions method synthesizes Li 4 Ru 0.01 Ti 4.99 O 12 /C anode material. → Combining the Ru-doped and carbon-coated techniques to fabricate Li 4 Ru 0.01 Ti 4.99 O 12 /C effectively enhance the diffusion rate of Li + and significantly reduce surface electronic resistance of Li 4 Ti 5 O 12 . → Li 4 Ru 0.01 Ti 4.99 O 12 /C delivers 120 and 110 mAh g -1 at 5 and 10 C charge/discharge rate, respectively, after 100 charge/discharge cycles. - Abstract: Pure Li 4 Ti 5 O 12 , modified Li 4 Ti 5 O 12 /C, Li 4 Ru 0.01 Ti 4.99 O 12 and Li 4 Ru 0.01 Ti 4.99 O 12 /C were successfully prepared by a modified solid-state method and its electrochemical properties were investigated. From the XRD patterns, the added sugar or doped Ru did not affect the spinel structure. The results of electrochemical properties revealed that Li 4 Ru 0.01 Ti 4.99 O 12 /C showed 120 and 110 mAh/g at 5 and 10 C rate after 100 charge/discharge cycles. Li 4 Ru 0.01 Ti 4.99 O 12 /C exhibited the best rate capability and the highest capacity at 5 and 10 C charge/discharge rate owing to the increase of electronic conductivity and the reduction of interface resistance between particles of Li 4 Ti 5 O 12 .It is expected that the Li 4 Ru 0.01 Ti 4.99 O 12 /C will be a promising anode material to be used in high-rate lithium ion battery.

  13. Antioxidants Inhibit Formation of 3-Monochloropropane-1,2-diol Esters in Model Reactions.

    Science.gov (United States)

    Li, Chang; Jia, Hanbing; Shen, Mingyue; Wang, Yuting; Nie, Shaoping; Chen, Yi; Zhou, Yongqiang; Wang, Yuanxing; Xie, Mingyong

    2015-11-11

    The capacities of six antioxidants to inhibit the formation of 3-monochloropropane-1,2 diol (3-MCPD) esters were examined in this study. Inhibitory capacities of the antioxidants were investigated both in chemical models containing the precursors (tripalmitoyl glycerol, 1,2-dipalmitoyl-sn-glycerol, monopalmitoyl glycerol, and sodium chloride) of 3-MCPD esters and in oil models (rapeseed oil and sodium chloride). Six antioxidants, butylated hydroxytoluene (BHT), butylated hydroxy anisole (BHA), tert-butyl hydroquinone (TBHQ), propyl gallate (PG), L-ascorbyl palmitate (AP), and α-tocopherol (VE), were found to exhibit inhibiting capacities on 3-MCPD ester formation both in chemical models and in oil models. TBHQ provided the highest inhibitory capacity both in chemical models and in oil models; 44% of 3-MCPD ester formation was inhibited in the presence of TBHQ (66 mg/kg of oil) after heating of rapeseed oil at 230 °C for 30 min, followed by PG and AP. BHT, BHA, and VE appeared to have weaker inhibitory abilities in both models. VE exhibited the lowest inhibition rate; 22% of 3-MCPD esters were inhibited in the presence of VE (172 mg/kg of oil) after heating of rapeseed oil at 230 °C for 30 min. In addition, the inhibition rates of PG and VE decreased dramatically with an increase in temperature or heating time. The results suggested that some antioxidants, such as TBHQ, PG, and AP, could be the potential inhibitors of 3-MCPD esters in practice.

  14. Graphene-oxide-supported CuAl and CoAl layered double hydroxides as enhanced catalysts for carbon-carbon coupling via Ullmann reaction

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Nesreen S. [Department of Chemistry, Faculty of Science, King Abdulaziz University (Saudi Arabia); Surface Chemistry and Catalytic Studies Group, King Abdulaziz University (Saudi Arabia); Menzel, Robert [Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Bio Nano Consulting, The Gridiron Building, One Pancras Square, London N1C 4AG (United Kingdom); Wang, Yifan [Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Garcia-Gallastegui, Ainara [Bio Nano Consulting, The Gridiron Building, One Pancras Square, London N1C 4AG (United Kingdom); Bawaked, Salem M.; Obaid, Abdullah Y.; Basahel, Sulaiman N. [Department of Chemistry, Faculty of Science, King Abdulaziz University (Saudi Arabia); Surface Chemistry and Catalytic Studies Group, King Abdulaziz University (Saudi Arabia); Mokhtar, Mohamed, E-mail: mmokhtar2000@yahoo.com [Department of Chemistry, Faculty of Science, King Abdulaziz University (Saudi Arabia); Surface Chemistry and Catalytic Studies Group, King Abdulaziz University (Saudi Arabia)

    2017-02-15

    Two efficient catalyst based on CuAl and CoAl layered double hydroxides (LDHs) supported on graphene oxide (GO) for the carbon-carbon coupling (Classic Ullmann Homocoupling Reaction) are reported. The pure and hybrid materials were synthesised by direct precipitation of the LDH nanoparticles onto GO, followed by a chemical, structural and physical characterisation by electron microscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), surface area measurements and X-ray photoelectron spectroscopy (XPS). The GO-supported and unsupported CuAl-LDH and CoAl-LDH hybrids were tested over the Classic Ullman Homocoupling Reaction of iodobenzene. In the current study CuAl- and CoAl-LDHs have shown excellent yields (91% and 98%, respectively) at very short reaction times (25 min). GO provides a light-weight, charge complementary and two-dimensional material that interacts effectively with the 2D LDHs, in turn enhancing the stability of LDH. After 5 re-use cycles, the catalytic activity of the LDH/GO hybrid is up to 2 times higher than for the unsupported LDH. - Graphical abstract: CuAl- and CoAl-LDHs have shown excellent yields (91% and 98%, respectively) at very short reaction times (25 min). GO provides a light-weight, charge complementary, two-dimensional material that interacts effectively with the 2D LDHs, in turn enhancing the stability of LDH. - Highlights: • CuAl LDH/GO and CoAl LDH/GO hybrid materials with different LDH compositions were prepared. • Hybrids were fully characterised and their catalytic efficiency over the Classic Ullman Reaction was studied. • CuAl- and CoAl-LDHs have shown excellent yields (91% and 98%, respectively) in 25 min reaction times. • GO provides a light-weight, charge complementary, two-dimensional material that interacts effectively with the 2D LDHs. • After 5 re-use cycles, the catalytic activity of the LDH/GO hybrid is up to 2 times higher than for the unsupported LDH.

  15. Measurement of the Induced Proton Polarization Pn in the 12C(e,e'rvec p) Reaction

    International Nuclear Information System (INIS)

    Woo, R.J.; Finn, J.M.; Jones, M.K.; McIntyre, J.I.; Perdrisat, C.F.; Barkhuff, D.H.; Lourie, R.W.; Milbrath, B.D.; Van Verst, S.P.; Bertozzi, W.; Dale, D.; Dodson, G.; Dow, K.A.; Farkhondeh, M.; Gilad, S.; Joo, K.; Kowalski, S.; Sarty, A.J.; Tieger, D.; Tschalaer, C.; Turchinetz, W.; Van Verst, S.P.; Warren, G.A.; Chen, J.P.; Mitchell, J.; Epstein, M.B.; Margaziotis, D.J.; Kelly, J.J.; Markowitz, P.; Madey, R.; Mertz, C.; Punjabi, V.; Rutt, P.M.; Ulmer, P.E.; Weinstein, L.; Vellidis, C.

    1998-01-01

    The first measurements of the induced proton polarization P n for the 12 C( e,e ' rvec p) reaction are reported. The experiment was performed at quasifree kinematics for energy and momentum transfer (ω,q)∼ (294 MeV, 756 MeV/c) and sampled a missing momentum range of 0 - 250 MeV/c. The induced polarization arises from final-state interactions and for these kinematics is dominated by the real part of the spin-orbit optical potential. The distorted-wave impulse approximation provides good agreement with data for the 1p 3/2 shell. The data for the continuum suggest that both the 1s 1/2 shell and underlying scr(l)>1 configurations contribute. copyright 1998 The American Physical Society

  16. Photochemical Reaction of 7,12-Dimethylbenz[a]anthracene (DMBA and Formation of DNA Covalent Adducts

    Directory of Open Access Journals (Sweden)

    Peter P. Fu

    2005-04-01

    Full Text Available DMBA, 7,12-dimethylbenz[a]anthracene, is a widely studied polycyclic aromatic hydrocarbon that has long been recognized as a probable human carcinogen. It has been found that DMBA is phototoxic in bacteria as well as in animal or human cells and photomutagenic in Salmonella typhimurium strain TA102. This article tempts to explain the photochemistry and photomutagenicity mechanism. Light irradiation converts DMBA into several photoproducts including benz[a]anthracene-7,12-dione, 7-hydroxy-12-keto-7-methylbenz[a]anthracene, 7,12-epidioxy-7,12-dihydro-DMBA, 7-hydroxymethyl-12-methylbenz[a]anthracene and 12-hydroxymethyl-7-methylbenz[a]anthracene. Structures of these photoproducts have been identified by either comparison with authentic samples or by NMR/MS. At least four other photoproducts need to be assigned. Photo-irradiation of DMBA in the presence of calf thymus DNA was similarly conducted and light-induced DMBA-DNA adducts were analyzed by 32P-postlabeling/TLC, which indicates that multiple DNA adducts were formed. This indicates that formation of DNA adducts might be the source of photomutagenicity of DMBA. Metabolites obtained from the metabolism of DMBA by rat liver microsomes were reacted with calf thymus DNA and the resulting DNA adducts were analyzed by 32P-postlabeling/TLC under identical conditions. Comparison of the DNA adduct profiles indicates that the DNA adducts formed from photo-irradiation are different from the DNA adducts formed due to the reaction of DMBA metabolites with DNA. These results suggest that photo-irradiation of DMBA can lead to genotoxicity through activation pathways different from those by microsomal metabolism of DMBA.

  17. Multiwalled carbon nanotubes@octavinyl polyhedral oligomeric silsesquioxanes nanocomposite preparation via cross-linking reaction in acidic media

    Energy Technology Data Exchange (ETDEWEB)

    Somasekharan, Lakshmipriya; Thomas, Sabu [Mahatma Gandhi University, International and Interuniversity Centre for Nanoscience and Nanotechnology (India); Comoy, Corinne [Université de Lorraine, SRSMC, UMR 7565 (France); Sivasankarapillai, Anilkumar [NSS Hindu College (India); Kalarikkal, Nandakumar [Mahatma Gandhi University, International and Interuniversity Centre for Nanoscience and Nanotechnology (India); Lamouroux, Emmanuel, E-mail: Emmanuel.Lamouroux@univ-lorraine.fr [Université de Lorraine, SRSMC, UMR 7565 (France)

    2016-11-15

    Multiwalled carbon nanotubes have unique properties allowing their use in a wide range of applications—from microelectronics to biomedical and polymer fields. Nevertheless, a crucial aspect for their use resides in the ease of handling them during the process. Here, we report a facile route to prepare multiwalled carbon nanotubes@octavinyl polyhedral oligomeric silsesquioxanes (MWCNT@POSS) nanocomposite. The method involves the formation of a covalent bond between carboxylated MWCNTs and OV-POSS using acid-catalyzed electrophilic addition reaction. The resulting nanocomposite have been characterized by Fourier transform infrared spectroscopy (FTIR), powder X-Ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The results confirmed that the formation of MWCNT@POSS nanocomposite did not deteriorate MWCNT structure or morphology. Here, we used a 1:1 ratio of carboxylated MWCNTs and OV-POSS and the POSS content in the nanocomposite was 39.5 wt%.

  18. Rapid synthesis of graphitic carbon nitride powders by metathesis reaction between CaCN2 and C2Cl6

    International Nuclear Information System (INIS)

    Pang Linlin; Bi Jianqiang; Bai Yujun; Qi Yongxin; Zhu Huiling; Wang Chengguo; Wu Jiwei; Lu Chengwei

    2008-01-01

    Carbon nitride powders were rapidly synthesized at low temperature via the chemical metathesis reaction between CaCN 2 and C 2 Cl 6 . X-ray diffraction results confirm the formation of crystalline graphitic carbon nitride. Besides the dominant morphology of nanoparticles, flakes, nanorods, hollow and solid spheres can be observed by transmission electron microscopy. The absorption peaks of C-N, C=N and s-triazine rings, as well as the absence of C≡N peak in the infrared spectra, further verify the formation of graphite-like sp 2 -bonded structure with planar networks. Elemental analysis gives an atomic ratio of N/C around 0.3. X-ray photoelectron spectra exhibit the existence of chemical bonding between C and N

  19. 1,2- and 1,3-dihydroxylated and hydroxynitrogenated monoterpenes as chiral ligands in the asymmetric reformatsky reaction

    International Nuclear Information System (INIS)

    Ribeiro, Carlos Magno R.; Morita, Cristina M.; Maia, Monica P.

    2008-01-01

    This study describes the use of three (-)-α-pinene derivatives, one diol-1,2 [(-)- (1R, 2R, 3S, 5R)-2,6,6-trimethylbicyclo[3.1.1]heptane-2,3-diol 4] and two pyridine-hydroxy derivatives [(+)-(1R,2S,3R,5S)-2,6,6- trimethyl-3-(2-pyridinylmethyl)bicyclo[3.1.1]heptane-3-ol 7 and (-)-(1R,2S,3R,5S)-2,6,6-trimethyl-3-[2-(2-pyridinyl) ethyl]bicyclo[3.1.1]heptane-3-ol 8]; one diol-1,3 [(-)-(1S,2R,5S)-2-(1-hydroxy-1-methylethyl)-5-methylcyclohexanol 5] derived from (+)-isopulegol 2 and one diol-1,3 [(+)-(1R,2R,5R)-2-(1-hydroxy-1-methylethyl)-5-methylcyclohexanol 6] derived from (+)-neoisopulegol 3, as ligands in the asymmetric Reformatsky reaction. The best enantiomeric excess of β-hydroxy ester obtained in the Reformatsky asymmetric reaction was 18% using ligand 6, and the chemical yield of the reactions was 65% on average. (author)

  20. A combined high-temperature experimental and theoretical kinetic study of the reaction of dimethyl carbonate with OH radicals

    KAUST Repository

    Khaled, Fathi

    2017-02-08

    The reaction kinetics of dimethyl carbonate (DMC) and OH radicals were investigated behind reflected shock waves over the temperature range of 872-1295 K and at pressures near 1.5 atm. Reaction progress was monitored by detecting OH radicals at 306.69 nm using a UV laser absorption technique. The rate coefficients for the reaction of DMC with OH radicals were extracted using a detailed kinetic model developed by Glaude et al. (Proc. Combust. Inst. 2005, 30(1), 1111-1118). The experimental rate coefficients can be expressed in Arrhenius form as: kexpt\\'l = 5.15 × 10(13) exp(-2710.2/T) cm(3) mol(-1) s(-1). To explore the detailed chemistry of the DMC + OH reaction system, theoretical kinetic analyses were performed using high-level ab initio and master equation/Rice-Ramsperger-Kassel-Marcus (ME/RRKM) calculations. Geometry optimization and frequency calculations were carried out at the second-order Møller-Plesset (MP2) perturbation level of theory using Dunning\\'s augmented correlation consistent-polarized valence double-ζ basis set (aug-cc-pVDZ). The energy was extrapolated to the complete basis set using single point calculations performed at the CCSD(T)/cc-pVXZ (where X = D, T) level of theory. For comparison purposes, additional ab initio calculations were also carried out using composite methods such as CBS-QB3, CBS-APNO, G3 and G4. Our calculations revealed that the H-abstraction reaction of DMC by OH radicals proceeds via an addition elimination mechanism in an overall exothermic process, eventually forming dimethyl carbonate radicals and H2O. Theoretical rate coefficients were found to be in excellent agreement with those determined experimentally. Rate coefficients for the DMC + OH reaction were combined with literature rate coefficients of four straight chain methyl ester + OH reactions to extract site-specific rates of H-abstraction from methyl esters by OH radicals.

  1. Synthesis and Characterization of Graphene and Graphene Oxide Based Palladium Nanocomposites and Their Catalytic Applications in Carbon-Carbon Cross-Coupling Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Minjae [Kunsan National Univ., Gunsan (Korea, Republic of); Kim, Bohyun; Lee, Yuna; Kim, Beomtae; Park, Joon B. [Chonbuk National Univ., Jeonju (Korea, Republic of)

    2014-07-15

    We have developed an efficient method to generate highly active Pd and PdO nanoparticles (NPs) dispersed on graphene and graphene oxide (GO) by an impregnation method combined with thermal treatments in H{sub 2} and O{sub 2} gas flows, respectively. The Pd NPs supported on graphene (Pd/G) and the PdO NPs supported on GO (PdO/GO) demonstrated excellent carbon-carbon cross-coupling reactions under a solvent-free, environmentally-friendly condition. The morphological and chemical structures of PdO/GO and Pd/G were fully characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). We found that the remarkable reactivity of the Pd/G and PdO/GO catalysts toward the cross-coupling reaction is attributed to the high degree of dispersion of the Pd and PdO NPs while the oxidative states of Pd and the oxygen functionalities of graphene oxide are not critical for their catalytic performance.

  2. Synthesis and Characterization of Graphene and Graphene Oxide Based Palladium Nanocomposites and Their Catalytic Applications in Carbon-Carbon Cross-Coupling Reactions

    International Nuclear Information System (INIS)

    Lee, Minjae; Kim, Bohyun; Lee, Yuna; Kim, Beomtae; Park, Joon B.

    2014-01-01

    We have developed an efficient method to generate highly active Pd and PdO nanoparticles (NPs) dispersed on graphene and graphene oxide (GO) by an impregnation method combined with thermal treatments in H 2 and O 2 gas flows, respectively. The Pd NPs supported on graphene (Pd/G) and the PdO NPs supported on GO (PdO/GO) demonstrated excellent carbon-carbon cross-coupling reactions under a solvent-free, environmentally-friendly condition. The morphological and chemical structures of PdO/GO and Pd/G were fully characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). We found that the remarkable reactivity of the Pd/G and PdO/GO catalysts toward the cross-coupling reaction is attributed to the high degree of dispersion of the Pd and PdO NPs while the oxidative states of Pd and the oxygen functionalities of graphene oxide are not critical for their catalytic performance

  3. Dimethyl carbonate synthesis via transesterification of propylene carbonate with methanol by ceria-zinc catalysts: Role of catalyst support and reaction parameters

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Praveen; Srivastava, Vimal Chandra; Mishra, Indra Mani [Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand (India)

    2015-09-15

    Ceria and zinc oxide catalyst were impregnated onto various oxide supports, namely Al{sub 2}O{sub 3}, TiO{sub 2} and SiO{sub 2}, individually by deposition-coprecipitation method. The synthesized catalysts (CZA, CZS and CZT having supports Al{sub 2}O{sub 3}, TiO{sub 2} and SiO{sub 2}, respectively) were characterized by X-ray diffraction (XRD), NH{sub 3}- and CO{sub 2}-temperature programmed desorption (TPD) and N2 adsorption. These catalysts were used for synthesis of dimethyl carbonate (DMC) from methanol and propylene carbonate in a batch reactor. CZS was found to have larger average grain size as compared to CZA and CZT. Composite oxides (catalysts) were found to contain individual phases of ZnO, CeO{sub 2} and some spinel forms of Zn, Ce along with their supports. CZS having highest basicity and surface area showed better catalytic activity as compared to CZA and CZT. Effect of reaction temperature and methanol/PC molar ratio on DMC yield was studied and a reaction mechanism has been discussed. Maximum DMC yield of 77% was observed with CZS catalyst at 170 .deg. C with methanol/PC molar ratio of 10.

  4. Wastage-resistant characteristics of 12Cr steel tube material. Small leak sodium-water reaction test

    International Nuclear Information System (INIS)

    Shimoyama, Kazuhito

    2004-03-01

    In the water leak accident of a steam generator designed for a sodium cooled reactor in the Feasibility Study, the localization of tube failure propagation by using an advanced water leak detector will be required from the viewpoints of the safety and economical efficiency of the plant. So far, the conventional knowledge and analytical tools have been used in the investigation and evaluation of water leak phenomenon; nevertheless, there was neither test data nor the study of quantitative evaluation on the corrosion behavior, so-called wastage-resistant characteristics, of 12Cr steel tube material in sodium-water reactions. Wastage tests for the 12Cr steel tube material were conducted in small water leaks by use of the Sodium-Water Reaction Test Rig (SWAT-1R), and the data of wastage rate were obtained in the parameter of water leak rate under the constant sodium temperature and distance between leak and target tubes. The test results lead to the following conclusions: (1) The wastage-resistibility of 12Cr steel is 1.6 times greater than that of 9Cr steel and is 2.7 times greater than that of 2.25Cr-1Mo steel. (2)The wastage-resistibility of 12Cr steel increases in smaller water leaks; especially in water leak rates of 1 g/sec or less, it is more excellent than that of SUS321 stainless steel used as Monju superheater tube material. (3) Based on the correlation of wastage rate for the 9Cr steel, the correlation for the 12Cr steel has been obtained to be used for the evaluation of tube failure propagation. As the correlation of wastage rate for the 12Cr steel is based on the correlation for the 9Cr steel, it gives enough conservatism in smaller water leaks. To serve in accurately evaluating the tube failure propagation in smaller water leaks, it is necessary to obtain new correlation of wastage rate for the 12Cr steel based on the data in the wide range of water leak rates. (author)

  5. Hydrogen evolution reaction at Ru-modified nickel-coated carbon fibre in 0.1 M NaOH

    Directory of Open Access Journals (Sweden)

    Pierożyński Bogusław

    2015-03-01

    Full Text Available The electrochemical activity towards hydrogen evolution reaction (HER was studied on commercially available (Toho-Tenax and Ru-modified nickel-coated carbon fibre (NiCCF materials. Quality and extent of Ru electrodeposition on NiCCF tows were examined by means of scanning electron microscopy (SEM. Kinetics of the hydrogen evolution reaction were investigated at room temperature, as well as over the temperature range: 20-50°C in 0.1 M NaOH solution for the cathodic overpotential range: -100 to -300 mV vs. RHE. Corresponding values of charge-transfer resistance, exchange current-density for the HER and other electrochemical parameters for the examined fibre tow composites were recorded.

  6. Synthesis of Al4SiC4 powders from kaolin grog, aluminum and carbon black by carbothermal reaction

    Science.gov (United States)

    Yuan, Wenjie; Yu, Chao; Deng, Chengji; Zhu, Hongxi

    2013-12-01

    In this paper, the synthesis of Al4SiC4 used as natural oxide materials by carbothermal reduction was investigated in order to explore the synthesis route with low costs. The samples were calcined by using kaolin grog, aluminum and carbon black as raw materials with the selected proportion at the temperature from 1500 to 1800 ° C for 2 hours under flow argon atmosphere. The phase composition of reaction products were determined by X-ray diffraction. The microstructure and elemental composition of different phases were observed and identified by scanning electron microscopy and energy dispersive spectroscopy. The mechanism of reaction processing was discussed. The results show that Al4SiC4 powders composed of hexagonal plate-like particulates with various sizes and the thickness of less than 20 μm are obtained when the temperature reaches 1800 °C.

  7. Synthesis of Al4SiC4 powders from kaolin grog, aluminum and carbon black by carbothermal reaction

    International Nuclear Information System (INIS)

    Yuan, Wenjie; Yu, Chao; Deng, Chengji; Zhu, Hongxi

    2013-01-01

    In this paper, the synthesis of Al 4 SiC 4 used as natural oxide materials by carbothermal reduction was investigated in order to explore the synthesis route with low costs. The samples were calcined by using kaolin grog, aluminum and carbon black as raw materials with the selected proportion at the temperature from 1500 to 1800 ° C for 2 hours under flow argon atmosphere. The phase composition of reaction products were determined by X-ray diffraction. The microstructure and elemental composition of different phases were observed and identified by scanning electron microscopy and energy dispersive spectroscopy. The mechanism of reaction processing was discussed. The results show that Al 4 SiC 4 powders composed of hexagonal plate-like particulates with various sizes and the thickness of less than 20 μm are obtained when the temperature reaches 1800 °C

  8. Stereoselective synthesis of organosulfur compounds incorporating N-aromatic heterocyclic motifs and quaternary carbon centers via a sulfa-Michael triggered tandem reaction.

    Science.gov (United States)

    Qin, Tianyou; Cheng, Lu; Zhang, Sean Xiao-An; Liao, Weiwei

    2015-06-14

    A novel sulfa-Michael addition (SMA)-triggered tandem reaction was developed by combining a SMA reaction with a simultaneous rearomatization process utilizing a less reactive carbonyl group as an intramolecular electrophile partner, which provided a unique synthetic route to access various organosulfur compounds incorporating an N-aromatic heterocyclic motif and quaternary carbon centers.

  9. Embedding nano-Li{sub 4}Ti{sub 5}O{sub 12} in hierarchical porous carbon matrixes derived from water soluble polymers for ultra-fast lithium ion batteries anodic materials

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Chun-Kai; Bao, Qi; Huang, Yao-Hui; Duh, Jenq-Gong, E-mail: jgd@mx.nthu.edu.tw

    2016-07-15

    Li{sub 4}Ti{sub 5}O{sub 12}/hierarchical porous carbon matrixes composites are successfully prepared by a facile and fast polymers assisted sol–gel method, aiming to promote both electronic and ionic conductivity. As indicated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis, three less expensive cost and available water soluble polymers (e.g. PAA, CMC, and SA) can homogeneously react with Li–Ti–O precursor to incorporate into interior of nano-scale lithium titanate and provide a continues conductive network after pyrolysis. In addition, the results of scanning electron microscopy and transmission electron microscopy also prove that the Li{sub 4}Ti{sub 5}O{sub 12} nanoparticles are firmly embedded in porous carbon matrix with no obvious agglomeration. EIS measurement and cyclic voltammetry further reveal that the facilitated electrode kinetics and better ionic transport of Li{sub 4}Ti{sub 5}O{sub 12}/hierarchical porous carbon matrixes composites than that of Li{sub 4}Ti{sub 5}O{sub 12}. The c-CMC-LTO exhibits a superior capacity of 92 mAh g{sup −1} and retains its initial value with no obviously capacity decay over 200 cycles under an ultra-high C rate (50 C). - Graphical abstract: Schematic illustrations of the formation process of embedding LTO into Carbon matrixes derived from water soluable polymers (upper) and the electrochemical reaction paths in LTO/Carbon composites during charging/discharging processes (lower). - Highlights: • Hierarchical porous carbon matrixes were used to improve the Li{sub 4}Ti{sub 5}O{sub 12} anodes. • Carbon matrixes could suppress the agglomeration of Li{sub 4}Ti{sub 5}O{sub 12} nanoparticles. • meso-nanoporous carbon structure was beneficial for filtration of electrolyte. • The c-CMC-LTO exhibited superior high rate capability and cycling durability.

  10. Double-step processes in the 12C(p,d)11C reaction at 45 MeV

    International Nuclear Information System (INIS)

    Couvert, Pierre.

    1974-01-01

    12 C(p,d) 11 C pick-up reaction was performed with a 45 MeV proton beam. A 130keV energy resolution was obtained and angular distributions of nine of the ten first levels of 11 C have been extracted within a large angular range. Assuming only neutron direct transfert, the strong relative excitation of high spin levels cannot be reproduced by a DWBA analysis. The double-step process assumption seems to be verified by a systematical analysis of the (p,d) reaction mechanisms. This analysis is done in the coupled-channel formalism for the five first negative parity states of 11 C. The 3/2 - ground state is essentially populated by the direct transfer of a Psub(3/2) neutron. The contribution of a double-step process, via the 2 + inelastic excitation of 12 C, is important for the four other states. A mechanism which assumes a deuteron inelastic scattering on the 11 C final nucleus after the neutron transfer cannot be neglected and improves the fits when it is taken into account [fr

  11. Role of alkali carbonate and salt in topochemical synthesis of K1/2Na1/2NbO3 and NaNbO3 templates

    Science.gov (United States)

    Lee, Jae-Seok; Jeon, Jae-Ho; Choi, Si-Young

    2013-11-01

    Since the properties of lead-free piezoelectric materials have thus far failed to meet those of lead-based materials, either chemical doping or morphological texturing should be employed to improve the piezoelectric properties of lead-free piezoelectric ceramics. The goal of this study was to synthesize plate-like K1/2Na1/2NbO3 and NaNbO3 particles, which are the most favorable templates for morphological texturing of K1/2Na1/2NbO3 ceramics. To achieve this goal, Bi2.5Na3.5Nb5O18 precursors in a plate-like shape were first synthesized and subsequently converted into K1/2Na1/2NbO3 or NaNbO3 particles that retain the morphology of Bi2.5Na3.5Nb5O18. In this study, we found that sodium or potassium carbonate does not play a major role in converting the Bi2.5Na3.5Nb5O18 precursor to K1/2Na1/2NbO3 or NaNbO3, on the contrary to previous reports; however, the salt contributes to the conversion reaction. All synthesis processes have been performed via a molten salt method, and scanning electron microscopy, scanning probe microscopy, and inductively coupled plasma mass spectroscopy were used to characterize the synthesized K1/2Na1/2NbO3 or NaNbO3 templates.

  12. Light-dark (12:12) cycle of carbon and nitrogen metabolism in Crocosphaera watsonii WH8501: relation to the cell cycle.

    Science.gov (United States)

    Dron, Anthony; Rabouille, Sophie; Claquin, Pascal; Le Roy, Bertrand; Talec, Amélie; Sciandra, Antoine

    2012-04-01

    This study provides with original data sets on the physiology of the unicellular diazotrophic cyanobacterium Crocosphaera watsonii WH8501, maintained in continuous culture in conditions of obligate diazotrophy. Cultures were exposed to a 12:12 light-dark regime, representative of what they experience in nature and where growth is expected to be balanced. Nitrogen and carbon metabolism were monitored at high frequency and their dynamics was compared with the cell cycle. Results reveal a daily cycle in the physiological and biochemical parameters, tightly constrained by the timely decoupled processes of N(2) fixation and carbon acquisition. The cell division rate increased concomitantly to carbon accumulation and peaked 6 h into the light. The carbon content reached a maximum at the end of the light phase. N(2) fixation occurred mostly during the dark period and peaked between 9 and 10 h into the night, while DNA synthesis, reflected by DNA fluorescence, increased until the end of the night. Consequently, cells in G1- and S-phases present a marked decrease in their C:N ratio. Nitrogen acquisition through N(2) fixation exceeded 1.3- to 3-fold the nitrogen requirements for growth, suggesting that important amounts of nitrogen are excreted even under conditions supposed to favour balanced, carbon and nitrogen acquisitions. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

  13. Preparation and Characterization of Pd Modified TiO2 Nanofiber Catalyst for Carbon–Carbon Coupling Heck Reaction

    Directory of Open Access Journals (Sweden)

    Leah O. Nyangasi

    2017-01-01

    Full Text Available TiO2 fibers were prepared through electrospinning of poly methyl methacrylate (PMMA and titanium isopropoxide (TIP solution followed by calcination of fibers in air at 500°C. Cetyltrimethylammonium bromide (CTAB protected palladium nanoparticles (Pd NPs prepared through reduction method were successfully adsorbed on the TiO2 nanofibers (NF. Combined studies of X-ray diffraction (XRD, scanning electron microscope (SEM, and transmission electron microscope (TEM indicated that the synthesized Pd/TiO2 had anatase. BET indicated that the synthesized TiO2 and Pd/TiO2 had a surface area of 53.4 and 43.4 m2/g, respectively. The activity and selectivity of 1 mol% Pd/TiO2 in the Heck reaction have been investigated towards the Mizoroki-Heck carbon–carbon cross-coupling of bromobenzene (ArBr and styrene. Temperature, time, solvent, and base were optimized and catalyst was recycled thrice. 1H NMR and 13C NMR indicated that stilbene, a known compound from literature, was obtained in various Heck reactions at temperatures between 100°C and 140°C but the recyclability was limited due to some palladium leaching and catalyst poisoning which probably arose from some residual carbon from the polymer. The catalyst was found to be highly active under air atmosphere with reaction temperatures up to 140°C. Optimized reaction condition resulted in 89.7% conversions with a TON of 1993.4 and TOF value of 332.2 hr−1.

  14. Centrality in Hadron-Carbon, Hadron-Lead, and Lead-Lead Reactions at 158 GeV/c

    International Nuclear Information System (INIS)

    Rybicki, A.

    2006-08-01

    A study of centrality in p + C, π + C, p + Pb, π + Pb, and Pb + Pb reactions is made. The analysis is performed by means of a simple geometrical model. The mean number of elementary collisions, , is estimated in minimum bias p + C reactions. For the specific case of the carbon nucleus, estimates on appear to depend strongly on assumed nuclear densities. Most realistic of the presented assumptions result in a value of 1.71 ± 0.05. Additional quantities, like predictions for the total inelastic cross-section in p + C reactions, or the number of participants in minimum bias C + C collisions, are given. The analysis is subsequently extended to minimum bias π + C, π + Pb, and p + Pb reactions. Estimates are given for the mean number of elementary collisions as well as for the contribution of single collisions P(1). A comparison with experimental data is made. Finally, the impact parameter dependence of p + Pb and Pb + Pb collisions is discussed. In view of future studies, various aspects of the analysis are discussed in detail; a bibliography of used references is included. (author)

  15. Chemical behaviour of plutonium in natural, aquatic systems: Hydrolysis, carbonate complexation and redox reactions

    International Nuclear Information System (INIS)

    Lierse, C.

    1985-01-01

    In order to clear up the geochemical behaviour of plutonium and its migration mechanisms in groundwater, hydrolysis, redox behaviour, compound formation in carbonate solutions and colloid formation were examined in groundwater conditions, i.e. at pH values between 5 and 8 and at redox potentials of between -300 and +700 mV. Solubility measurements, spectroscopic processes (UV, VIS, IR spectroscopy and laser induced photoacoustic spectroscopy) and electrochemical processes (cyclic voltammetry, differential pulse polarography) are used as methods of investigation. The hydrolysis constants of Pu IV and Pu VI and the solubility product of Pu (OH) 4 were determined and hydrolysis products of divalent and trivalent type are described. From solubility experiments, the stability constants for Pu (IV) carbonate compounds and the solubility product for the carbonate system of stable bodies of Pu (OH) 2 CO 3 were calculated. Using absorption spectroscopy, the disproportionate kinetics of Pu (V) in carbonate was determined at various pH values. A slow, but continuous, reduction in Pu (VI) was found in carbonate solution, which was derived from radiolytic effects. The speed of this auto-reduction was determined, depending on various experimental parameters. (orig./RB) [de

  16. Formation of carbonato and hydroxo complexes in the reaction of platinum anticancer drugs with carbonate.

    Science.gov (United States)

    Di Pasqua, Anthony J; Centerwall, Corey R; Kerwood, Deborah J; Dabrowiak, James C

    2009-02-02

    The second-generation Pt(II) anticancer drug carboplatin is here shown to react with carbonate, which is present in blood, interstitial fluid, cytosol, and culture medium, to produce platinum-carbonato and -hydroxo complexes. Using [(1)H-(15)N] HSQC NMR and (15)N-labeled carboplatin, we observe that cis-[Pt(CBDCA-O)(OH)(NH(3))(2)](-), cis-[Pt(OH)(2)(NH(3))(2)], cis-[Pt(CO(3))(OH)(NH(3))(2)](-), and what may be cis-[Pt(CO(3))(NH(3))(2)] are produced when 1 is allowed to react in 23.8 mM carbonate buffer. When (15)N-labeled carboplatin is allowed to react in 0.5 M carbonate buffer, these platinum species, as well as other hydroxo and carbonato species, some of which may be dinuclear complexes, are produced. Furthermore, we show that the carbonato species cis-[Pt(CO(3))(OH)(NH(3))(2)](-) is also produced when cisplatin is allowed to react in carbonate buffer. The study outlines the conditions under which carboplatin and cisplatin form carbonato and aqua/hydroxo species in carbonate media.

  17. Quasi-bound alpha resonant states populated by the {sup 12}C({sup 6}Li, d) reaction

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, M.R.D.; Borello-Lewin, T.; Miyake, H.; Horodynski-Matsushigue, L.B.; Duarte, J.L.M.; Rodrigues, C.L.; Souza, M.A. [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica; Cunsolo, A.; Cappuzzello, F.; Foti, A.; Agodi, C.; Cavallaro, M. [Istituto Nazionale di Fisica Nucleare (LNS/INFN), Catania (Italy). Lab. Nazionali del Sud; Ukita, G.M. [Universidade de Santo Amaro (UNISA), Sao Paulo, SP (Brazil). Faculdade de Psicologia

    2012-07-01

    Full text: The alpha cluster phenomenon in the light nuclei structure has been the subject of a long time investigation since the proposal of the Ikeda diagrams [1]. The main purpose of the research program in progress is the investigation of this phenomenon in (x{alpha}) and (x{alpha}+n) nuclei through the ({sup 6}Li, d) alpha transfer reaction [2-4]. Alpha resonant states around the (4{alpha}) threshold in the nucleus {sup 16}O are the focus of the present contribution. In fact, the importance of these resonances at the elements production in stars is recognized, as primarily pointed out by Hoyle in {sup 12}C [6]. The existence of a rotational band with the {alpha} +{sup 12} C (Hoyle) cluster state structure was recently demonstrated by Ohkubo and Hirabayashi [6]. In order to explore this region of interest, measurements of the {sup 12}C({sup 6}Li, d){sup 16}O reaction up to 17 MeV of excitation at an incident energy of 25.5 MeV, have been performed employing the Sao Paulo Pelletron-Enge Split-Pole facility and the nuclear emulsion detection technique (plates Fuji G6B, 50 {mu}m thick). Spectra associated with six scattering angles, from 5 deg to 29 deg in the laboratory frame, each one 50 cm along the focal surface, were measured. Several narrow resonances with a quasi-bound behavior embedded in the continuum were detected and the resolution of 25 keV allowed for the separation of doublets not resolved before [7,8]. The absolute cross sections and the respective deuteron angular distributions were determined and the analysis is in progress. [1] K. Ikeda et al., Prog. Theor. Phys. Suppl. E 68, 464 (1968); H. Horiuchi, K. Ikeda, and Y. Suzuki, ibid. 44, 225 (1978). [2] M.R.D.Rodrigues et al., in12th International Conference on Nuclear Reaction Mechanism, Varenna, Italy, edited by F. Cerutti and A. Ferrari , CERN Proceedings, 2010-2, pp. 331- 335. [3] T. Borello-Lewin et al., Proceedings of SOTANCP2, Brussels, Belgium 2010, edited by P. Descouvemount et al., Int. J

  18. Micro-Raman spectroscopy investigation of the carbonation reaction in a lime paste produced with a traditional technology

    Czech Academy of Sciences Publication Activity Database

    Ševčík, Radek; Mácová, Petra; Sotiriadis, Konstantinos; Pérez-Estébanez, Marta; Viani, Alberto; Šašek, Petr

    2016-01-01

    Roč. 47, č. 12 (2016), s. 1452-1457 ISSN 0377-0486 R&D Projects: GA ČR(CZ) GP14-20374P; GA MŠk(CZ) LO1219 Keywords : calcite * carbonation * lime paste * micro-Raman spectroscopy * portlandite Subject RIV: AL - Art, Architecture, Cultural Heritage Impact factor: 2.969, year: 2016 http://onlinelibrary.wiley.com/doi/10.1002/jrs.4929/full

  19. Cesium Carbonate as a Heterogeneous Base Catalyst for Synthesis of 2-Aminothiophenes via Gewald Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Moeinpour, Farid [Islamic Azad University, Bandar Abbas Branch, Abbas (Iran, Islamic Republic of); Omidinia, Raheleh; Dorostkar-Ahmadi, Nadieh; Khoshdeli, Bentalhoda [Islamic Azad University, Mashhad Branch, Mashhad (Iran, Islamic Republic of)

    2011-06-15

    We have reported a new simple catalytic method for the synthesis of 2-aminothiophenes via Gewald reaction using Cs{sub 2}CO{sub 3} as an efficient, reusable and green heterogeneous catalyst under heating conditions in refluxing ethanol. The catalyst could be recycled after a simple workup and reused at least three runs without appreciable reduction in its catalytic activity. Low catalyst loading, clean reaction profiles, simple experimental and workup procedures and high yields are some advantages of this protocol. The synthesis of substituted 2-aminothiophenes is attractive to chemical researchers as they are important intermediates in organic synthesis and frequently used as the scaffold motif of a variety of agrochemicals, dyes, and biologically active products. Thus, because of their wide utility, researchers have synthesized the substituted 2-aminothiophenes via efficient and convenient methods. The one-pot cyclocondensation of ketones with an activated α-hydrogen, a cyanomethylene containing an electron-withdrawing group such as cyanoacetate and elemental sulfur in the presence of organic base, for example, morpholine, diethylamine, etc, known as the Gewald reaction, has been one of the most well-studied multicomponent reactions in recent years. To extend the scope of the reaction, many alterations have been made to the original Gewald's base-catalyzed, two-component combination of α-mercapto ketones with cyanoacetate by varying the components and the conditions.

  20. Mesoporous N-doped carbons prepared with thermally removable nanoparticle templates: an efficient electrocatalyst for oxygen reduction reaction.

    Science.gov (United States)

    Niu, Wenhan; Li, Ligui; Liu, Xiaojun; Wang, Nan; Liu, Ji; Zhou, Weijia; Tang, Zhenghua; Chen, Shaowei

    2015-04-29

    Thermally removable nanoparticle templates were used for the fabrication of self-supported N-doped mesoporous carbons with a trace amount of Fe (Fe-N/C). Experimentally Fe-N/C was prepared by pyrolysis of poly(2-fluoroaniline) (P2FANI) containing a number of FeO(OH) nanorods that were prepared by a one-pot hydrothermal synthesis and homogeneously distributed within the polymer matrix. The FeO(OH) nanocrystals acted as rigid templates to prevent the collapse of P2FANI during the carbonization process, where a mesoporous skeleton was formed with a medium surface area of about 400 m(2)/g. Subsequent thermal treatments at elevated temperatures led to the decomposition and evaporation of the FeO(OH) nanocrystals and the formation of mesoporous carbons with the surface area markedly enhanced to 934.8 m(2)/g. Electrochemical measurements revealed that the resulting mesoporous carbons exhibited apparent electrocatalytic activity for oxygen reduction reactions (ORR), and the one prepared at 800 °C (Fe-N/C-800) was the best among the series, with a more positive onset potential (+0.98 V vs RHE), higher diffusion-limited current, higher selectivity (number of electron transfer n > 3.95 at +0.75 V vs RHE), much higher stability, and stronger tolerance against methanol crossover than commercial Pt/C catalysts in a 0.1 M KOH solution. The remarkable ORR performance was attributed to the high surface area and sufficient exposure of electrocatalytically active sites that arose primarily from N-doped carbons with minor contributions from Fe-containing species.

  1. Radiation-induced chemical reactions of carbon monoxide and hydrogen mixture

    International Nuclear Information System (INIS)

    Sugimoto, S.; Nishii, M.; Sugiura, T.

    1984-01-01

    The radiation chemical reaction of CO-H 2 mixture has been studied in the pressure range from 10 4 to 1.3 x 10 5 Pa using 7 l. reaction vessel made of stainless steel. Various hydrocarbons and oxygen containing compounds such as methane, formaldehyde, acetaldehyde, and methanol have been obtained as radiolytic products. The amounts and the G values of these products depended upon the irradiation conditions such as composition of reactant, total pressure, reaction temperature, and dose. It was found that the irradiation at low dose produced small amounts of trioxane and tetraoxane, which have not yet been reported in literature. The yields of these cyclic ethers increased at high pressure and at low temperature. An experiment was also made on CO-H 2 mixture containing ammonia as a cation scavenger to investigate the precursor of these products. (author)

  2. Modelling the 13C and 12C isotopes of inorganic and organic carbon in the Baltic Sea

    Science.gov (United States)

    Gustafsson, Erik; Mörth, Carl-Magnus; Humborg, Christoph; Gustafsson, Bo G.

    2015-08-01

    In this study, 12C and 13C contents of all carbon containing state variables (dissolved inorganic and organic carbon, detrital carbon, and the carbon content of autotrophs and heterotrophs) have for the first time been explicitly included in a coupled physical-biogeochemical Baltic Sea model. Different processes in the carbon cycling have distinct fractionation values, resulting in specific isotopic fingerprints. Thus, in addition to simulating concentrations of different tracers, our new model formulation improves the possibility to constrain the rates of processes such as CO2 assimilation, mineralization, and air-sea exchange. We demonstrate that phytoplankton production and respiration, and the related air-sea CO2 fluxes, are to a large degree controlling the isotopic composition of organic and inorganic carbon in the system. The isotopic composition is further, but to a lesser extent, influenced by river loads and deep water inflows as well as transformation of terrestrial organic carbon within the system. Changes in the isotopic composition over the 20th century have been dominated by two processes - the preferential release of 12C to the atmosphere in association with fossil fuel burning, and the eutrophication of the Baltic Sea related to increased nutrient loads under the second half of the century.

  3. Suppression of interfacial reactions between Li4Ti5O12 electrode and electrolyte solution via zinc oxide coating

    International Nuclear Information System (INIS)

    Han, Cuiping; He, Yan-Bing; Li, Hongfei; Li, Baohua; Du, Hongda; Qin, Xianying; Kang, Feiyu

    2015-01-01

    Graphical abstract: The Li 4 Ti 5 O 12 (LTO) based batteries have severe gassing behavior due to the strong interfacial reactions between LTO and the electrolyte solution, which hampers the practical application of LTO in high power LIBs. The ZnO coating on LTO particles as a barrier layer can effectively suppress the interfacial reactions between LTO and the electrolyte solution. Simultaneously, the ZnO coating significantly reduces the charge-transfer resistance and increases the lithium ion diffusion coefficient, which leads to great improvement of rate and cyclic performance of LTO electrode. - Highlights: • A ZnO coating layer was constructed on the LTO particles by a chemical process as a barrier layer between LTO and surrounding electrolyte solution. • The ZnO coating can effectively stabilize the electrode/electrolyte interface and suppress interfacial reactions between LTO and electrolyte solution. • The ZnO coating can improve the electronic conductivity and lithium ion diffusion coefficient, which contributes to a great improvement in cyclic and high rate capabilities of LTO electrode. • The ZnO coating on LTO may be an effective method to solve the gassing behavior of LTO based battery and promote its wide application in lithium ion power battery. - Abstract: Li 4 Ti 5 O 12 (LTO) based batteries have severe gassing behavior during charge/discharge and storage process. The interfacial reactions between LTO and electrolyte solution may be the main reason. In this work, the LTO spinel particles are modified with ZnO coating using a chemical process to reduce the surface reactivity of LTO particles. Results show that the ZnO coating can effectively stabilize the electrode/electrolyte interface and suppress the formation of a solid electrolyte interface (SEI) film. Simultaneously, this ZnO modification can improve the electronic conductivity and lithium ion diffusion coefficient, which contributes to a great improvement in cyclic and high rate

  4. Influence of charge state on the reaction of FeO3+/- with carbon monoxide

    Science.gov (United States)

    Reilly, Nelly M.; Ulises Reveles, J.; Johnson, Grant E.; Khanna and, Shiv N., Jr.; Castleman, A. W.

    2007-02-01

    A combined experimental and theoretical study shows that highly oxidized iron clusters are able to readily effect the oxidation of CO to CO 2 at ambient temperature. Calculated energy profiles of the reaction demonstrate that the oxidation efficiency is governed by the strength of oxygen binding to the iron atom. Results for FeO3+/- are presented and reveal that cation clusters are more efficient than the corresponding anion clusters at effecting the oxidation reaction due to different oxygen bond energies resulting from charge distribution.

  5. Supercritical carbon dioxide as an innovative reaction medium for selective oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Loeker, F.; Leitner, W. [Max-Planck-Institut fuer Kohlenforschung, Muelheim an der Ruhr (Germany)

    1998-12-31

    Although the catalytic efficiency of all catalytic oxidation processes studied in scCO{sub 2} up to now is far from being satisfactory, the principle possibility to carry out such reactions in this medium is clearly evident. Future research in our group will be directed towards the development of homogeneous and heterogeneous catalysts that are adopted to the special requirements of both the oxidation process and the supercritical reaction medium. Preliminary results from these studies regarding the epoxidation of olefins with molecular oxygen as oxidant will be presented on the conference poster. (orig.)

  6. Simplified modeling of simultaneous reaction kinetics of carbon oxidation and nitrification in biofilm processes

    Energy Technology Data Exchange (ETDEWEB)

    Tsuneda, S.; Auresenia, J.; Hibiya, K.; Hirata, A. [Waseda University, Department of Chemical Engineering, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555 (Japan)

    2004-06-01

    Batch experiments with varying initial substrate concentrations and biomass volumes were performed in a three-phase fluidized bed biofilm reactor treating simulated domestic wastewater to study the simultaneous carbon oxidation and nitrification in the biofilm process. A simplified mass balance equation for the biofilm was proposed and five different kinetic rate equations were used to match the actual data. The kinetic parameters were obtained by nonlinear regression analysis on a set of two differential equations representing the simultaneous carbon oxidation and nitrification. The competitive inhibition model incorporating the effects of total organic carbon (TOC) concentrations on nitrification rates was the best-suited model based on the average r{sup 2}. In this model, oxygen concentration and its affinity constants were not included. Instead, it was assumed that the rate of carbon oxidation is independent of the NH{sub 4}{sup +}-N, while nitrification is affected by TOC. The number of parameters was successfully minimized without reducing its ability to accurately predict the bulk concentration time course, which would reduce computational complexity and possibly enhance the availability for an actual wastewater treatment process. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

  7. Determination of the percentage of quitine desacetilation reaction by solid state carbon-13 NMR

    International Nuclear Information System (INIS)

    Ferracin, Ricardo J.; Cass, Quezia B.; Bassi, Ana L.

    1997-01-01

    Quitine is a bi-polymer largely found in invertebrates. As most compounds of this class are insoluble in common organic solvents, the des-acetylation percentile was obtained by carbon-13 solid state nuclear magnetic resonance. The methodology is presented. Results are presented

  8. Catalytic activity of metall-like carbides in carbon oxide oxidation reaction

    International Nuclear Information System (INIS)

    Kharlamov, A.I.; Kosolapova, T.Ya.; Rafal, A.N.; Kirillova, N.V.

    1980-01-01

    Kinetics of carbon oxide oxidation upon carbides of hafnium, niobium, tantalum, molybdenum, zirconium and chromium is studied. Probable mechanism of the catalysts action is suggested. The established character of the change of the carbide catalytic activity is explained by the change of d-electron contribution to the metal-metal interaction

  9. Analysis of unburned carbon in industrial ashes from biomass combustion by thermogravimetric method using Boudouard reaction

    Czech Academy of Sciences Publication Activity Database

    Straka, Pavel; Náhunková, Jana; Žaloudková, Margit

    2014-01-01

    Roč. 575, JAN (2014), s. 188-194 ISSN 0040-6031 R&D Projects: GA MZe QI102A207 Institutional support: RVO:67985891 Keywords : unburned carbon * biomass * ash * thermogravimetry Subject RIV: GD - Fertilization, Irrigation, Soil Processing Impact factor: 2.184, year: 2014 http://www.sciencedirect.com/science/article/pii/S0040603113005455

  10. Fabrication of calcite blocks from gypsum blocks by compositional transformation based on dissolution-precipitation reactions in sodium carbonate solution.

    Science.gov (United States)

    Ishikawa, Kunio; Kawachi, Giichiro; Tsuru, Kanji; Yoshimoto, Ayami

    2017-03-01

    Calcium carbonate (CaCO 3 ) has been used as a bone substitute, and is a precursor for carbonate apatite, which is also a promising bone substitute. However, limited studies have been reported on the fabrication of artificial calcite blocks. In the present study, cylindrical calcite blocks (ϕ6×3mm) were fabricated by compositional transformation based on dissolution-precipitation reactions using different calcium sulfate blocks as a precursor. In the dissolution-precipitation reactions, both CaSO 4 ·2H 2 O and CaSO 4 transformed into calcite, a polymorph of CaCO 3 , while maintaining their macroscopic structure when immersed in 1mol/L Na 2 CO 3 solution at 80°C for 1week. The diametral tensile strengths of the calcite blocks formed using CaSO 4 ·2H 2 O and CaSO 4 were 1.0±0.3 and 2.3±0.7MPa, respectively. The fabrication of calcite blocks using CaSO 4 ·2H 2 O and CaSO 4 proposed in this investigation may be a useful method to produce calcite blocks because of the self-setting ability and high temperature stability of gypsum precursors. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Stoichiometric control in Bi4Ti3O12 synthesis by novel hybrid solid state reaction

    DEFF Research Database (Denmark)

    Gadea, C.; Phatharapeetranun, N.; Ksapabutr, B.

    2018-01-01

    The synthesis of bismuth titanate Bi4Ti3O12 (BiT) is performed via a novel solid state reaction. The reaction is designed to control the stoichiometric content of the highly volatile element, i.e. Bi. The chemical route consists in trapping bismuth oxide colloids in a stabilized titanium based sol...

  12. Electrocatalytic studies of osmium-ruthenium carbonyl cluster compounds for their application as methanol-tolerant cathodes for oxygen reduction reaction and carbon monoxide-tolerant anodes for hydrogen oxidation reaction

    Energy Technology Data Exchange (ETDEWEB)

    Borja-Arco, E.; Uribe-Godinez, J.; Castellanos, R.H. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Escobedo (Mexico); Altamirano-Gutierrez, A.; Jimenez-Sandoval, O. [Centro de Investigacion y de Estudios Avanzados del Inst. Politecnico Nacional, Querataro (Mexico)

    2006-07-01

    This paper provided details of an electrokinetic study of novel electrocatalytic materials capable of performing both the oxygen reduction reaction (ORR) and the hydrogen oxidation reaction (HOR). Osmium-ruthenium carbonyl cluster compounds (Os{sub x}Ru{sub 3}(CO){sub n}) were synthesized by chemical condensation in non-polar organic solvents at different boiling points and refluxing temperatures. Three different non-polar organic solvents were used: (1) n-nonane; o-xylene; and 1,2-dichlorobenzene. The electrocatalysts were characterized by Fourier Transform Infra-red (FTIR) spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). A rotating disk electrode technique was used to analyze the materials. Results of the analysis showed that the materials performed ORR in both the presence and absence of carbon monoxide (CO), and that electrocatalysts were not poisoned by the presence of CO. Cyclic voltamperometry for the disk electrodes showed that the electrochemical behaviour of the compounds in the acid electrolyte was similar in the presence or absence of methanol. The Tafel slope, exchange current density and the transfer coefficient were also investigated. The electrokinetic parameters for the ORR indicated that the materials with the highest electrocatalytic activity were synthesized in 1,2-dichlorobenzene. Electrocatalytic activity during HOR were prepared in n-nonane. It was concluded that the new materials are good candidates for use as both a cathode and an anode in proton exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs). 7 refs., 2 tabs., 7 figs.

  13. Master curves for the sulphur assisted crosslinking reaction of natural rubber in the presence of nano- and nano-structured sp2 carbon allotropes

    Directory of Open Access Journals (Sweden)

    S. Musto

    2017-06-01

    Full Text Available In this paper, master curves are reported for the crosslinking of a diene rubber with a sulphur based system in the presence of either nano- or nano-structured carbon allotropes, such as carbon nanotubes (CNT, a nanosized graphite with high surface area (HSAG and carbon black (CB. Poly(1,4-cis-isoprene from Hevea Brasiliensis was the diene rubber and crosslinking was performed in temperatures ranging from 151 to 180 °C, with carbon allotropes below and above their percolation threshold. Such carbon allotropes were characterized by different aspect ratio, surface area and pH. However, in the crosslinking reaction, they revealed common behaviour. In fact, the specific interfacial area could be used to correlate crosslinking parameters, such as induction time (ts1 and activation energy (Ea calculated by applying the autocatalytic model. Monotonous decrease of ts1 and increase of Ea were observed, with points lying on master curves, regardless of the nature of the carbon allotropes. Remarkable differences were however observed in the structure of the crosslinking network: when the carbon allotrope was above the percolation threshold much larger crosslinking density was obtained in the presence of CNT whereas composites based on HSAG became soluble in hydrocarbon solvent, after the reaction with a thiol. Proposed explanation of these results is based on the reactivity of carbon allotropes with sulphur and sulphur based compounds, demonstrated through the reaction of 1-dodecanethiol and sulphur with CNT and HSAG and with a model substrate such as anthracene.

  14. Measurement of Fragment Production Cross Sections in the $^{12}$C+$^{12}$C and $^{12}$C+$^{197}$Au Reactions at 62 $A$ MeV for Hadrontherapy and Space Radiation Protection

    CERN Document Server

    Tropea, S; Agodi, C; Blancato, A A; Bondì, M; Cappuzzello, F; Carbone, D; Cavallaro, M; Cirrone, G A P; Cuttone, G; Giacoppo, F; Nicolosi, D; Pandola, L; Raciti, G; Rapisarda, E; Romano, F; Sardina, D; Scuderi, V; Sfienti, C

    2014-01-01

    Over the last twenty years, there has been a renewed interest in nuclear fragmentation studies for both hadrontherapy applications and space radiation protection. In both fields, fragmentation cross sections are needed to predict the effects of the ions nuclear interactions within the patient’s and the astronaut’s body. Indeed, the Monte Carlo codes used in planning tumor treatments and space missions must be tuned and validated by experimental data. However, only a limited set of fragmentation cross sections are available in literature, especially at Fermi energies. Therefore, we have studied the production of secondary fragments in the 12 C+ 12 C and 12 C+ 197 Au reactions at 62 A MeV. In this work, the measured 4 He cross sections angular distributions at four selected angles are presented and compared.

  15. Sustainable ways of combining reactions and separations using ionic liquids and carbon dioxide

    NARCIS (Netherlands)

    Kazemi, S.

    2013-01-01

    Traditional chemical processes show shortcomings caused by using volatile organic compounds as solvents during reactions and separations. Therefore, it is necessary to address this issue by moving toward more environmentally friendly processes. This is possible by using less toxic and hazardous

  16. Sustainable Ways of Combining Reactions and Separations Using Ionic Liquids and Carbon Dioxide

    NARCIS (Netherlands)

    Kazemi, S.

    2013-01-01

    Traditional chemical processes show shortcomings caused by using volatile organic compounds as solvents during reactions and separations. Therefore, it is necessary to address this issue by moving toward more environmentally friendly processes. This is possible by using less toxic and hazardous

  17. Atomic platinum layer coated titanium copper nitride supported on carbon nanotubes for the methanol oxidation reaction

    CSIR Research Space (South Africa)

    Zheng, Y

    2017-09-01

    Full Text Available measurements. The results confirm the core-shell structure of the prepared TiN@Pt/CNTs catalyst. More importantly, the catalyst exhibits superb mass activity and durability for the methanol oxidation reaction (MOR) than that of the commercial JM Pt/C catalyst...

  18. Stable and efficient nitrogen-containing-carbon based electrocatalysts for reactions in energy conversion systems.

    Science.gov (United States)

    Wang, Sicong; Teng, Zhenyuan; Wang, Chengyin; Wang, Guoxiu

    2018-05-17

    High activity and stability are crucial for practical electrocatalysts used for reactions in fuel cells, metal-air batteries and water electrolysis including ORR, HER, OER and oxidation reactions of formic acid and alcohols. N-C based electrocatalysts have shown promising prospects for catalyzing these reactions, however, there is no systematic review for strategies toward engineering active and stable N-C based electrocatalysts reported by far. Herein, a comprehensive comparison of recently reported N-C based electrocatalysts regarding both electrocatalytic activity and long-term stability is presented. In the first part of this review, relationships between electrocatalytic reactions and element selections for modifying N-C based materials are discussed. Afterwards, synthesis methods for N-C based electrocatalysts are summarized, and synthetic strategies for highly stable N-C based electrocatalysts are presented. Multiple tables containing data on crucial parameters for both electrocatalytic activity and stability are displayed in this review. Finally, constructing M-Nx moieties is proposed as the most promising engineering strategy for stable N-C based electrocatalysts. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Ruthenium supported on nitrogen-doped carbon nanotubes for the oxygen reduction reaction in alkaline

    CSIR Research Space (South Africa)

    Mabena, LF

    2012-10-01

    Full Text Available between 0 and 10 wt.%. The activity of the prepared nanocatalysts toward the oxygen reduction reaction (ORR) was characterized using the rotating disk electrode and voltammetry techniques. The ORR activity was higher at lower concentrations of Ru on N...

  20. A Dramatic Classroom Demonstration of Limiting Reagent Using the Vinegar and Sodium Hydrogen Carbonate Reaction

    Science.gov (United States)

    Artdej, Romklao; Thongpanchang, Tienthong

    2008-01-01

    This demonstration is designed to illustrate the concept of limiting reagent in a spectacular way. Via a series of experiments where the amount of vinegar is fixed and the amount of NaHCO[subscript 3] is gradually increased, the volume of CO[subscript 2] generated from the reaction varies corresponding to the amount of NaHCO[subscript 3] until it…

  1. Influence of limestone powder on the reaction kinetics and mechanical properties of sodium carbonate activated slag

    NARCIS (Netherlands)

    Yuan, B.; Yu, Q.; Brouwers, H.J.H.

    2016-01-01

    The effects of limestone powder (LP) on the performance of Portland cement based composites have been extensively studied, considering that LP not only acts as nuclei sites, but that it is also chemically involved in the hydration process, which improves the reaction degree at the early age. In high

  2. Effect of reverse Boudouard reaction catalyst on the performance of solid oxide carbon fuel cells integrated with a dry gasifier

    International Nuclear Information System (INIS)

    Kim, Sun-Kyung; Mehran, Muhammad Taqi; Mushtaq, Usman; Lim, Tak-Hyoung; Lee, Jong-Won; Lee, Seung-Bok; Park, Seok-Joo; Song, Rak-Hyun

    2016-01-01

    Highlights: • The addition of K_2CO_3 catalyst in carbon fuel improves the performance of SO-CFC. • Thermal and electrochemical analyses done to elucidate the catalytic enhancement. • Material characterization of SO-CFC performed after long-term degradation test. - Abstract: A solid oxide carbon fuel cell (SO-CFC) integrated with a dry gasifier was operated on activated carbon fuel and the effect of adding a reverse Boudouard gasification catalyst on the performance and long-term operation characteristics of the SO-CFC was investigated. The reactivity of the carbon fuels for the Boudouard gasification reaction was analyzed by a thermal analysis at various operating conditions. The SO-CFC was then operated on gasified fuel gas consisting of CO_2 and CO obtained from the integrated dry gasifier. The SO-CFC operated on activated carbon fuel with 5 wt.% K_2CO_3 achieved a maximum power density of 202, 262, and 271 mW/cm"2 at 750, 800, and 850 °C, respectively; the SO-CFC fueled with activated carbon fuel without a catalyst meanwhile yielded maximum power density of 168 mW/cm"2 at 850 °C. By using electrochemical impedance spectroscopy, the effect of adding the catalyst on the gasification products and subsequently on the performance of the SO-CFC was studied. A long-term degradation test was conducted by continuously operating the SO-CFC at 50 mA/cm"2 for 518 h at 750 °C. During the long-term degradation test, the average degradation rate of the SO-CFC was found to be 183 mV/kh. The post-mortem SEM and XRD analyses of the SO-CFC after the long-term test revealed the presence of carbon deposits and oxidation of Ni at the anode, causing a relatively higher degree of degradation in the SO-CFC integrated with the dry gasifier during the long-term operation. The addition of the K_2CO_3 based dry gasification catalyst significantly enhances the performance of the SO-CFC integrated with dry gasification, but during long-term operation, the degradation rate is found

  3. An efficient and high-yielding one-pot synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones catalyzed by sodium hydrogen carbonate under solvent-free conditions

    OpenAIRE

    Asieh Vafaee; Abolghasem Davoodnia; Mehdi Pordel; Mohammad Reza Bozorgmehr

    2015-01-01

    Sodium hydrogen carbonate, NaHCO3, efficiently catalyzes the one-pot, three-component reaction of phthalhydrazide, an aromatic aldehyde, and malononitrile or ethyl cyanoacetate under solvent-free conditions, to afford the corresponding 1H-pyrazolo[1,2-b]phthalazine-5,10-diones in high yields. Easy work‐up, inexpensive and readily available catalyst and avoiding the use of harmful organic solvents are other advantages of this simple procedure.

  4. Electrophysiological Monitoring in Patients With Tumors of the Skull Base Treated by Carbon-12 Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Carozzo, Simone [Department of Neuroscience, Ophthalmology, and Genetics, University of Genova, Genova (Italy); Schardt, Dieter [Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt (Germany); Narici, Livio [Department of Physics, University of Rome Tor Vergata, Rome (Italy); Combs, Stephanie E.; Debus, Jürgen [Department of Radiation Oncology, University of Heidelberg, Heidelberg (Germany); Sannita, Walter G., E-mail: wgs@dism.unige.it [Department of Neuroscience, Ophthalmology, and Genetics, University of Genova, Genova (Italy); Department of Psychiatry, State University of New York, Stony Brook, New York (United States)

    2013-03-15

    Purpose: To report the results of short-term electrophysiologic monitoring of patients undergoing {sup 12}C therapy for the treatment of skull chordomas and chondrosarcomas unsuitable for radical surgery. Methods and Materials: Conventional electroencephalogram (EEG) and retinal and cortical electrophysiologic responses to contrast stimuli were recorded from 30 patients undergoing carbon ion radiation therapy, within a few hours before the first treatment and after completion of therapy. Methodologies and procedures were compliant with the guidelines of the International Federation for Clinical Neurophysiology and International Society for Clinical Electrophysiology of Vision. Results: At baseline, clinical signs were reported in 56.6% of subjects. Electrophysiologic test results were abnormal in 76.7% (EEG), 78.6% (cortical evoked potentials), and 92.8% (electroretinogram) of cases, without correlation with neurologic signs, tumor location, or therapy plan. Results on EEG, but not electroretinograms and cortical responses, were more often abnormal in patients with reported clinical signs. Abnormal EEG results and retinal/cortical responses improved after therapy in 40% (EEG), 62.5% (cortical potentials), and 70% (electroretinogram) of cases. Results on EEG worsened after therapy in one-third of patients whose recordings were normal at baseline. Conclusions: The percentages of subjects whose EEG results improved or worsened after therapy and the improvement of retinal/cortical responses in the majority of patients are indicative of a limited or negligible (and possibly transient) acute central nervous system toxicity of carbon ion therapy, with a significant beneficial effect on the visual pathways. Research on large samples would validate electrophysiologic procedures as a possible independent test for central nervous system toxicity and allow investigation of the correlation with clinical signs; repeated testing over time after therapy would demonstrate, and may

  5. Investigation of reaction mechanisms during electroreduction of carbon dioxide on lead electrode for the production of organic compounds

    International Nuclear Information System (INIS)

    Innocent, B.

    2008-09-01

    The aim of this work was to promote the reduction of CO 2 through its electrochemical conversion (electro-synthesis) on a lead electrode into high added value products. Depending on the nature of electrolyte, the electro-reduction of carbon dioxide leads to different products. Various electrolytes (aqueous or organic, protic or aprotic) were used to study two mechanisms: hydrogenation (formation of formate) and electro-dimerization (synthesis of oxalate). Cyclic voltammetry studies have been carried out for electrochemically characterizing CO 2 reduction on Pb. The electrochemical investigation of the electrode electrolyte interface has shown that the process of CO 2 electro-reduction is a mass transfer control both in the organic and aqueous media. Electrochemical experiments (cyclic voltammetry, chrono-amperometry) coupled with in situ infrared reflectance spectroscopic techniques (SPAIRS, SNIFTIRS) have also shown that in aqueous medium (7 ≤pH≤9) hydrogeno-carbonate ions were reduced to formate. The modification of solvent (propylene carbonate) leads selectively to oxalate as the main reaction product. Long-term electrolyses were performed in a filter-press cell to deal large volumes. In aqueous medium, the reduction of HCO 3 - to HCOO - (R F = 89% at -2.5 mA cm -2 and 4 C) is always accompanied by the production of H 2 . (author)

  6. (PC12) cell lines to oxidized multi-walled carbon nanotubes

    African Journals Online (AJOL)

    EB

    Methods: The pristine multi-walled carbon nanotubes (p-MWCNTs) were ... characterize the MWCNTs. ..... South Africa and NRF Focus Area, Nanotechnology ... of carbon nanotubes in drug delivery. Current. Opinion in Chemical Biology, 2005 ...

  7. ZIF-67 incorporated with carbon derived from pomelo peels: A highly efficient bifunctional catalyst for oxygen reduction/evolution reactions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hao; Yin, Feng-Xiang; Chen, Biao-Hua; He, Xiao-Bo; Lv, Peng-Liang; Ye, Cai-Yun; Liu, Di-Jia

    2017-05-01

    Developing carbon catalyst materials using natural, abundant and renewable resources as precursors plays an increasingly important role in clean energy generation and environmental protection. In this work, N-doped pomelo-peel-derived carbon (NPC) materials were prepared using a widely available food waste-pomelo peels and melamine. The synthetic NPC exhibits well-defined porosities and a highly doped-N content (e.g. 6.38 at% for NPC-2), therefore affords excellent oxygen reduction reaction (ORR) catalytic activities in alkaline electrolytes. NPC was further integrated with ZIF-67 to form ZIF-67@NPC hybrids through solvothermal reactions. The hybrid catalysts show substantially enhanced ORR catalytic activities comparable to that of commercial 20 wa Pt/C. Furthermore, the catalysts also exhibit excellent oxygen evolution reaction (OER) catalytic activities. Among all prepared ZIF-67@NPC hybrids, the optimal composition with ZIF-67 to NPC ratio of 2:1 exhibits the best ORR and OER bifunctional catalytic performance and the smallest Delta E (E-OER@10 mA cm(-2)-E-ORR@-1 mA cm(-2)) value of 0.79 V. The catalyst also demonstrated desirable 4-electron transfer pathways and superior catalytic stabilities. The Co-N-4 in ZIF-67, electrochemical active surface area, and the strong interactions between ZIF-67 and NPC are attributed as the main contributors to the bifunctional catalytic activities. These factors act synergistically, resulting in substantially enhanced bifunctional catalytic activities and stabilities; consequently, this hybrid catalyst is among the best of the reported bifunctional electrocatalysts and is promising for use in metal-air batteries and fuel cells. (C) 2016 Elsevier B.V. All rights reserved.

  8. Mathematical modeling of the lithium deposition overcharge reaction in lithium-ion batteries using carbon-based negative electrodes

    International Nuclear Information System (INIS)

    Arora, P.; Doyle, M.; White, R.E.

    1999-01-01

    Two major issues facing lithium-ion battery technology are safety and capacity grade during cycling. A significant amount of work has been done to improve the cycle life and to reduce the safety problems associated with these cells. This includes newer and better electrode materials, lower-temperature shutdown separators, nonflammable or self-extinguishing electrolytes, and improved cell designs. The goal of this work is to predict the conditions for the lithium deposition overcharge reaction on the negative electrode (graphite and coke) and to investigate the effect of various operating conditions, cell designs and charging protocols on the lithium deposition side reaction. The processes that lead to capacity fading affect severely the cycle life and rate behavior of lithium-ion cells. One such process is the overcharge of the negative electrode causing lithium deposition, which can lead to capacity losses including a loss of active lithium and electrolyte and represents a potential safety hazard. A mathematical model is presented to predict lithium deposition on the negative electrode under a variety of operating conditions. The Li x C 6 vertical bar 1 M LiPF 6 , 2:1 ethylene carbonate/dimethyl carbonate, poly(vinylidene fluoride-hexafluoropropylene) vert b ar LiMn 2 O 4 cell is simulated to investigate the influence of lithium deposition on the charging behavior of intercalation electrodes. The model is used to study the effect of key design parameters (particle size, electrode thickness, and mass ratio) on the lithium deposition overcharge reaction. The model predictions are compared for coke and graphite-based negative electrodes. The cycling behavior of these cells is simulated before and after overcharge to understand the hazards and capacity fade problems, inherent in these cells, can be minimized

  9. Effect of reaction environments on the reactivity of PCB (2-chlorobiphenyl) over activated carbon impregnated with palladized iron

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Hyeok [Department of Civil Engineering, University of Texas at Arlington, 416 Yates Drive, Arlington, TX 76019-0308 (United States); Al-Abed, Souhail R., E-mail: al-abed.souhail@epa.gov [National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 West Martin Luther King Drive, Cincinnati, OH 45268 (United States)

    2010-07-15

    Reactive activated carbon (RAC) impregnated with palladized iron nanoparticles has been developed to treat polychlorinated biphenyls (PCBs). In this study, we evaluated the effects of various reaction environments on the adsorption-mediated dechlorination of 2-chlorobiphenyl (2-ClBP) in the RAC system. The results were discussed in close connection to the implementation issue of the RAC system for the remediation of contaminated sites with PCBs. Adsorption event of 2-ClBP onto RAC limited the overall performance under condition with a 2-ClBP/RAC mass ratio of less than 1.0 x 10{sup -4} above which dechlorination of 2-ClBP adsorbed to RAC was the reaction rate-determining step. Acidic and basic conditions were harmful to 2-ClBP adsorption and iron stability while neutral pH showed the highest adsorption-promoted dechlorination of 2-ClBP and negligible metal leaching. Coexisting natural organic matter (NOM) slightly inhibited 2-ClBP adsorption onto RAC due to the partial partitioning of 2-ClBP into NOM in the liquid phase while the 2-ClBP absorbed into NOM, which also tended to adsorb onto RAC, was less available for the dechlorination reaction. Common anions slowed down 2-ClBP adsorption but adsorbed 2-ClBP was almost simultaneously dechlorinated. Some exceptions included strong inhibitory effect of carbonate species on 2-ClBP adsorption and severe detrimental effect of sulfite on 2-ClBP dechlorination. Results on treatment of 2-ClBP spiked to actual sediment supernatants implied site-specific reactivity of RAC.

  10. Carbon Leakage in the Primary Aluminium Sector: What evidence after 6 1/2 years of the EU ETS? - Working Paper No. 2012-12

    International Nuclear Information System (INIS)

    Sartor, Oliver

    2012-02-01

    This paper provides an econometric analysis of the evidence of carbon leakage from the European primary aluminium industry during the first 6 1/2 years of the EU ETS. The findings suggest that while rising electricity prices have played a critical role in reducing the competitiveness of EU primary aluminium smelting in recent years, no evidence of carbon leakage can be detected so far. Other factors, including rising primary energy prices and changes in EU competition law regarding long term contracts, appear to be more important factors explaining the rise in net imports of primary aluminium and the gradual closure of a number of European primary smelters during the past 6 1/2 years. Our results suggest that the carbon leakage debate in this sector may therefore be better seen in terms of not accelerating the decline of the industry in Europe, rather than preventing it, and that any state-aid to the industry to prevent carbon leakage should therefore be applied accordingly. (author)

  11. Study of Target Fragmentation in the Interaction of 86 MeV/A $^{12}$Carbon with Tantalum, Bismuth and Uranium

    CERN Multimedia

    2002-01-01

    Using radiochemical techniques we will ; a)~~measure the target fragment mass and charge distributions from the interaction of 86~MeV/A |1|2C with Ta, Bi and U; ; b)~~measure the target fragment forward momentum and average kinetic energy using the thick target-thick catcher technique for the above reactions; and ; c)~~measure the target fragment angular and differential energy distributions using thin target-thin catcher techniques for the reactions with Ta and U. \\\\ \\\\ These measurements should allow us to better characterize the transition between low energy and realistic heavy ion reaction mechanisms.

  12. Study of the Particle Production in $^{12}$C Induced Heavy Ion Reactions at 86 MeV/N

    CERN Multimedia

    2002-01-01

    The aim of this experiment is to study various characteristics of light and heavy particle production in |1|2C induced reactions if possible over the whole unexplored energy region 50-86~MeV/N. In particular we want to investigate how the correlations in the multiparticle events can help us to distinguish bet existing models. \\\\ \\\\ Two-proton large-angle correlations and correlations between two heavier (Z~=~1 or 2) particles are studied with scintillator +~NaI and range telescopes, complemented with a 24 telescope scintillator wall for projectile fragments. Thereby we receive information about the reaction plane and the impact parameter in coincidence with the two-particle correlation spectra. Small @Dp correlations can also be studied. The inclusive @p|+ and @p|- production has been followed far below the nucleon-nucleon threshold. Pions are thereby identified from @DE-E correlations and the @p|+ decay in plastic range telescopes. These results are now followed up by @p-projectile fragment and @p-p correlat...

  13. Hypernuclear production cross section in the reaction of 6Li + 12C at 2A GeV

    Directory of Open Access Journals (Sweden)

    C. Rappold

    2015-07-01

    Full Text Available Hypernuclear production cross sections have been deduced for the first time with induced reaction of heavy ion beam on fixed target and by means of the invariant mass method by the HypHI Collaboration exploiting the reaction of 6Li + 12C at 2A GeV or sNN=2.70 GeV. A production cross section of 3.9±1.4 μb for 3ΛH and of 3.1±1.0 μb for 4ΛH respectively in the projectile rapidity region was inferred as well as the total production cross section of the Λ hyperon was measured and found to be equal to 1.7±0.8 mb. A global fit based on a Bayesian approach was performed in order to include and propagate statistical and systematic uncertainties. Production ratios of 3ΛH/4ΛH, 3ΛH/Λ and 4ΛH/Λ were included in the inference procedure. The strangeness population factors S3 and S4 of 3ΛH and 4ΛH respectively were extracted. In addition, the multiplicities of the Λ hyperon, 3ΛH, and 4ΛH together with the rapidity and transversal momentum density distributions of the observed hypernuclei were extracted and reported.

  14. High resolution spectroscopy of the 12Lambda B hypernucleus produced by the (e,e'K+) reaction.

    Science.gov (United States)

    Miyoshi, T; Sarsour, M; Yuan, L; Zhu, X; Ahmidouch, A; Ambrozewicz, P; Androic, D; Angelescu, T; Asaturyan, R; Avery, S; Baker, O K; Bertovic, I; Breuer, H; Carlini, R; Cha, J; Chrien, R; Christy, M; Cole, L; Danagoulian, S; Dehnhard, D; Elaasar, M; Empl, A; Ent, R; Fenker, H; Fujii, Y; Furic, M; Gan, L; Garrow, K; Gasparian, A; Gueye, P; Harvey, M; Hashimoto, O; Hinton, W; Hu, B; Hungerford, E; Jackson, C; Johnston, K; Juengst, H; Keppel, C; Lan, K; Liang, Y; Likhachev, V P; Liu, J H; Mack, D; Margaryan, A; Markowitz, P; Martoff, J; Mkrtchyan, H; Nakamura, S N; Petkovic, T; Reinhold, J; Roche, J; Sato, Y; Sawafta, R; Simicevic, N; Smith, G; Stepanyan, S; Tadevosyan, V; Takahashi, T; Tanida, K; Tang, L; Ukai, M; Uzzle, A; Vulcan, W; Wells, S; Wood, S; Xu, G; Yamaguchi, H; Yan, C

    2003-06-13

    High-energy, cw electron beams at new accelerator facilities allow electromagnetic production and precision study of hypernuclear structure, and we report here on the first experiment demonstrating the potential of the (e,e'K+) reaction for hypernuclear spectroscopy. This experiment is also the first to take advantage of the enhanced virtual photon flux available when electrons are scattered at approximately zero degrees. The observed energy resolution was found to be approximately 900 keV for the (12)(Lambda)B spectrum, and is substantially better than any previous hypernuclear experiment using magnetic spectrometers. The positions of the major excitations are found to be in agreement with a theoretical prediction and with a previous binding energy measurement, but additional structure is also observed in the core excited region, underlining the future promise of this technique.

  15. Spectroscopy of #Lambda#28Al, #Lambda#12B and #Lambda#7He by the (e,e(prime)K+) Reaction

    International Nuclear Information System (INIS)

    Matsumura, Akihiko

    2010-01-01

    Hypernuclear spectroscopy by the (e,e(prime)K + ) reaction is one of the powerful tools to investigate precise structures of hypernuclei and to study ΛN interaction. The second generation hypernuclear experiment at JLab Hall C(E01-011) was successfully performed in 2005, introducing the two novel experimental configurations, High resolution and large acceptance Kaon Spectrometer(HKS) and Tilt method. Thanks to these new configurations, various hypernuclei such as # Lambda# 28 Al, # Lambda# 12 B and # Lambda# 7 He were measured with precise energy resolution of 500 keV (FWHM). Obtained absolute binding energies and cross sections were compared with other experimental data and recent theoretical calculations based on shell model and cluster model. The results of this study provided new information on ΛN interaction.

  16. Photosynthetic light reactions increase total lipid accumulation in carbon-supplemented batch cultures of Chlorella vulgaris.

    Science.gov (United States)

    Woodworth, Benjamin D; Mead, Rebecca L; Nichols, Courtney N; Kolling, Derrick R J

    2015-03-01

    Microalgae are an attractive biofuel feedstock because of their high lipid to biomass ratios, lipid compositions that are suitable for biodiesel production, and the ability to grow on varied carbon sources. While algae can grow autotrophically, supplying an exogenous carbon source can increase growth rates and allow heterotrophic growth in the absence of light. Time course analyses of dextrose-supplemented Chlorella vulgaris batch cultures demonstrate that light availability directly influences growth rate, chlorophyll production, and total lipid accumulation. Parallel photomixotrophic and heterotrophic cultures grown to stationary phase reached the same amount of biomass, but total lipid content was higher for algae grown in the presence of light (an average of 1.90 mg/mL vs. 0.77 mg/mL over 5 days of stationary phase growth). Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Thermodynamics of calcium-isotope-exchange reactions. 1. Exchange between isotopic calcium carbonates and aqueous calcium ions

    International Nuclear Information System (INIS)

    Zhang, R.S.; Nash, C.P.; Rock, P.A.

    1988-01-01

    This paper reports the authors results for the direct experimental determination of the equilibrium constant for the calcium-isotope-exchange reaction 40 CaCO 3 (s) + 44 CaCl 2 (aq) reversible 44 CaCO 2 (s) + 40 CaCl 2 (aq). The reaction was studied in electrochemical double cells without liquid junction of the type shown in eq 2. The experimental value of the equilibrium constant at 295 +/- 2 K is K = 1.08 +/- 0.02. The experimental value for K is compared with the values of K calculated for various model reactions according to the statistical thermodynamic theory of isotope effects. The isotopic solid carbonates were modeled according to both the Debye and Kieffer theories. No structured models of solvated isotopic aqueous calcium ions yield calculated equilibrium constants in agreement with their experimental results. This conclusion is in agreement with published molecular dynamics calculations which show that the aqueous solvation of Ca 2 =(aq) is essentially unstructured

  18. The reaction between carbon tetrachloride and hydrogen induced by gamma radiation

    International Nuclear Information System (INIS)

    Molinari, M.A.; Strehar, N.R.; Videla, G.J.

    1975-11-01

    The products observed are HCl (yield G = 27-250), CHCl 3 (G = 1,4-15), C 2 Cl 6 (G = 2,5-4) and C 2 HCl 5 , C 2 Cl 4 and CH 2 Cl 2 (in smaller ammounts). G values change with absorbed energy (total dose) (1-100 . 10 19 eV), dose rate (1,7 . 10 19 to 1,7 . 10 18 eV/g.h.) and proportion of reactants. A possible simplified mechanism is presented, as a chain reaction initiated by free radicals, which only explains cuantitatively some results at high doses. It is evident that the primary mechanisms include several types of cocurrent reactions. (author) [es

  19. Influence of Charge State on the Reaction of FeO3^+/- with Carbon Monoxide

    Science.gov (United States)

    Reveles, J. U.; Khanna, S. N.; Reilly, N. M.; Johnson, G. E.; Castleman, A. W., Jr.

    2007-03-01

    A synergistic study combining experiments in molecular beams and first principles electronic structure calculations within a gradient corrected density functional approach is used to investigate the reactivity of charged FeO3 clusters with CO. It is shown that highly oxidized iron clusters are able to readily effect the oxidation of CO to CO2 at ambient temperature. Calculated energy profiles of the reaction demonstrate that the oxidation efficiency is governed by the strength of oxygen binding to the iron atom. Results for FeO3^+/- are presented and reveal that cation clusters are more efficient than the corresponding anion clusters at effecting the oxidation reaction due to different bond energies resulting from charge distribution.

  20. Nickel group cluster anion reactions with carbon monoxide: Rate coefficients and chemisorption efficiency

    Science.gov (United States)

    Hintz, Paul A.; Ervin, Kent M.

    1994-04-01

    Reactions of Ni-n(n=3-10), Pd-n(n=3-8), and Pt-n(n=3-7) with CO are studied in a flow tube reactor. Bimolecular rate coefficients are measured for the association reaction of CO adsorbing on the cluster surface. The rate coefficients range from about 10% of the collision rate for the trimer anions to near the collision rate for clusters larger than four atoms. The maximum number of CO molecules that bind to each cluster is determined. Whereas the saturation limits for nickel are typical for an 18 electron transition metal, the limits for platinum are lower, reflecting the electron deficient structures observed in condensed phase chemistry. The CO saturated palladium clusters represent the first examples of saturated binary palladium carbonyl compounds. Comparisons are made to similar studies on metal cation and neutral clusters and also to surface scattering studies of nickel group metals.

  1. Irradiation effect on the reaction of mixture of carbon monoxide and hydrogen, (3)

    International Nuclear Information System (INIS)

    Sugimoto, Shun-ichi; Nishii, Masanobu

    1983-08-01

    A series of our studies on radiation chemical reaction of CO and H 2 mixture indicated that several organic compounds were produced by electron beam irradiation and the amounts of the products increased with increasing pressure and also increased when the irradiation was carried out under circulation. The present study was carried out in an attempt to investigate whether the amounts of the products increase when the mixture is irradiated under circulation at elevated pressure. For this purpose, a reaction apparatus, which can irradiated the mixture up to 10,000 Torr under circulation, was built and the experiments were carried out on the amounts of products as functions of pressure, irradiation time, gas composition, temperature and dose rate. G values of most compounds were found to increased with increasing pressure under circulation. Among the products, the reaction conditions giving high yield of acetaldehyde were studied in detail, since this compound is considered to be one of the most important intermediate compounds in C 1 chemistry. The maximum G value of acetaldehyde was 2.9 which was obtained at 8,000 Torr, 55 CO mol%, 2 x 10 19 eV.g -1 .sec -1 , 1.3 x 10 20 eV.g -1 and 22 0 C. The selectivity favored this compounds in all organic compounds was 57 mol% at the conversion rate of 0.8 %. In order to elucidate the reaction paths of formation and disappearance of acetaldehyde, the amounts of products were determined for the mixture with or without the presence of small amounts of acetadehyde. The results indicate that acetaldehyde formed by irradiation from

  2. Syntheses of carbon porous materials with varied pore sizes and their performances as catalyst supports during methanol oxidation reaction

    International Nuclear Information System (INIS)

    Lo, An-Ya; Hung, Chin-Te; Yu, Ningya; Kuo, Cheng-Tzu; Liu, Shang-Bin

    2012-01-01

    Highlights: ► CPMs with varied pore sizes (1–400 nm) were replicated from various porous silicas by CVI method. ► MOR activities of Pt/CPM electrocatalysts increase with increasing pore size of CPM support. ► Microporous CPMs are favorable supports for Pt in terms of catalytic performance and CO-tolerance. -- Abstract: Carbon porous materials (CPMs) with extended ranges of pore size and morphology were replicated using various porous silicas, such as zeolites, mesoporous silicas, and photonic crystals, as templates by means of chemical vapor infiltration (CVI) method. The micro-, meso-, and macro-porous carbons so fabricated were adopted as supports for the metal (Pt) catalyst for direct methanol fuel cells (DMFCs), and the supported Pt/CPM electrocatalysts were characterized by a variety of different spectroscopic/analytical techniques, viz. transmission electron microscopy (TEM), Raman, X-ray photoelectron spectroscopy (XPS), gas physisorption/chemisorption analyses, and cyclic voltammetry (CV). That these Pt/CPMs were found to exhibit superior electrocatalytic activities compared to the commercial Pt/XC-72 with a comparable Pt loading during methanol oxidation reaction (MOR) is attributed to the presence of Pt nanoparticles (NPs; typically 1–3 nm in size) that are highly dispersed in the CPMs, facilitating an improved tolerance for CO poisoning. While the MOR activity observed for various Pt/CPMs tend to increase with increasing pore size of the carbon supports, Pt catalyst supported on carbon substrates possessing microporosities was found to have superior stability in terms of tolerance for CO poisoning than those with greater pore size or having meso- and macroporosities.

  3. Synthesis of graphitized carbon, nanodiamond and graphene supported Li4Ti5O12 and comparison of their electrochemical performance as anodes for lithium ion batteries

    Science.gov (United States)

    Yang, Shuai; Miao, Juan; Wang, Qiufen; Lu, Mengwei; Sun, Jiufang; Wen, Tao

    2016-12-01

    Graphitized carbon (GC), nanodiamond (ND) and graphene (GE) supported Li4Ti5O12 (LTO) composites have been synthesized via a solid-state reaction, respectively. The particle sizes of LTO/GC, LTO/ND and LTO/GE are smaller than pure LTO. When tested as the anode for lithium ion batteries, the discharge capacities of LTO, LTO/GC, LTO/ND and LTO/GE composites are 100.1 mAh g-1, 150.4 mAh g-1, 90.4 mAh g-1 and 218.3 mAh g-1 at the current density of 175 mA g-1 after 500 cycles. Their rate capacities retain 59.8%, 80.0%, 81.0% and 85.7% at the current density of 175 mA g-1, 438 mA g-1, 875 mA g-1 and 175 mA g-1, respectively. Moreover, the recovery rates of their rate capacities are 78.6%, 83.4%, 88.9% and 90.1% when returned to the current density of 175 mA g-1, respectively. The reasons can be attributed to the synergistic effect between GC (ND and GE) and LTO as well as the features of the different carbon supports. This strategy, with the carbon constituting a good supporting structure, is an effective way to improve the cycling performance of anode materials for lithium ion batteries.

  4. Measurement of the 12C(e,e‧p)11B two-body breakup reaction at high missing momentum

    Science.gov (United States)

    Monaghan, P.; Shneor, R.; Subedi, R.; Anderson, B. D.; Aniol, K.; Annand, J.; Arrington, J.; Benaoum, H. B.; Benmokhtar, F.; Bertin, P.; Bertozzi, W.; Boeglin, W.; Chen, J. P.; Choi, Seonho; Chudakov, E.; Ciofi degli Atti, C.; Cisbani, E.; Cosyn, W.; Craver, B.; de Jager, C. W.; Feuerbach, R. J.; Folts, E.; Frullani, S.; Garibaldi, F.; Gayou, O.; Gilad, S.; Gilman, R.; Glamazdin, O.; Gomez, J.; Hansen, O.; Higinbotham, D. W.; Holmstrom, T.; Ibrahim, H.; Igarashi, R.; Jans, E.; Jiang, X.; Kaufman, L.; Kelleher, A.; Kolarkar, A.; Kuchina, E.; Kumbartzki, G.; LeRose, J. J.; Lindgren, R.; Liyanage, N.; Margaziotis, D. J.; Markowitz, P.; Marrone, S.; Mazouz, M.; Meekins, D.; Michaels, R.; Moffit, B.; Morita, H.; Nanda, S.; Perdrisat, C. F.; Piasetzky, E.; Potokar, M.; Punjabi, V.; Qiang, Y.; Reinhold, J.; Reitz, B.; Ron, G.; Rosner, G.; Ryckebusch, J.; Saha, A.; Sawatzky, B.; Segal, J.; Shahinyan, A.; Širca, S.; Slifer, K.; Solvignon, P.; Sulkosky, V.; Thompson, N.; Ulmer, P. E.; Urciuoli, G. M.; Voutier, E.; Wang, K.; Watson, J. W.; Weinstein, L. B.; Wojtsekhowski, B.; Wood, S.; Yao, H.; Zheng, X.; Zhu, L.

    2014-10-01

    The five-fold differential cross section for the 12C{{(e,{{e}^{\\prime }}p)}^{11}}B reaction was determined over a missing momentum range of 200-400 MeV\\;{{c}^{-1}}, in a kinematics regime with {{x}_{B}}\\gt 1 and {{Q}^{2}}=2.0 {{(GeV\\;{{c}^{-1}})}^{2}}. A comparison of the results with previous lower missing momentum data and with theoretical models are presented. The extracted distorted momentum distribution is shown to be consistent with previous data and extends the range of available data up to 400 MeV\\;{{c}^{-1}}. The theoretical calculations are from two very different approaches, one mean field and the other short range correlated; yet for this system the two approaches show striking agreement with the data and each other up to a missing momentum value of 325 MeV\\;{{c}^{-1}}. For larger momenta, the calculations diverge which is likely due to the factorization approximation used in the short range approach.

  5. Metal cluster cation reactions: Carbon monoxide association to Cu + n ions

    Science.gov (United States)

    Leuchtner, R. E.; Harms, A. C.; Castleman, A. W., Jr.

    1990-06-01

    Copper cluster cations (Cu+n,n=1-14) were produced in a laser vaporization/flow tube apparatus and equilibrated to room temperature. The association rate constants of carbon monoxide onto these ions were measured; low-pressure, termolecular behavior was observed for the smaller species while for clusters greater than Cu+7, the longer lifetimes due to the increased number of degrees of freedom leads to pressure independence (>0.3 Torr) of the effective bimolecular rates. Unimolecular decay theory (RRKM) is used to explain the overall trend and when intrinsic surface site reactivity is taken into account, excellent agreement with measured reactivity is obtained.

  6. Functionalization of Carbon Nanotubes via Electrophilic Substitution Reaction in Polyphosphoric Acid

    Science.gov (United States)

    2006-07-26

    single fiber. The resulting fiber bundles were chopped, collected, and washed with diluted ammonium hydroxide, and then Soxhlet -extracted with water...quantitative yield . Anal. Calcd. for C14.98H8O2: C, 81.78%; H, 3.67%. Found: C, 80.19%; H, 3.61%. 3. Results and Discussion 3.1 Characterization of MWNT...carbon nanomaterials. Furthermore, Soxhlet extractions of MWNT-g-mPEK and VGCNF- g-mPEK with dichloromethane, which is good solvent for mPEK, were

  7. A palladium-doped ceria@carbon core-sheath nanowire network: a promising catalyst support for alcohol electrooxidation reactions

    Science.gov (United States)

    Tan, Qiang; Du, Chunyu; Sun, Yongrong; Du, Lei; Yin, Geping; Gao, Yunzhi

    2015-08-01

    A novel palladium-doped ceria and carbon core-sheath nanowire network (Pd-CeO2@C CSNWN) is synthesized by a template-free and surfactant-free solvothermal process, followed by high temperature carbonization. This hierarchical network serves as a new class of catalyst support to enhance the activity and durability of noble metal catalysts for alcohol oxidation reactions. Its supported Pd nanoparticles, Pd/(Pd-CeO2@C CSNWN), exhibit >9 fold increase in activity toward the ethanol oxidation over the state-of-the-art Pd/C catalyst, which is the highest among the reported Pd systems. Moreover, stability tests show a virtually unchanged activity after 1000 cycles. The high activity is mainly attributed to the superior oxygen-species releasing capability of Pd-doped CeO2 nanowires by accelerating the removal of the poisoning intermediate. The unique interconnected one-dimensional core-sheath structure is revealed to facilitate immobilization of the metal catalysts, leading to the improved durability. This core-sheath nanowire network opens up a new strategy for catalyst performance optimization for next-generation fuel cells.A novel palladium-doped ceria and carbon core-sheath nanowire network (Pd-CeO2@C CSNWN) is synthesized by a template-free and surfactant-free solvothermal process, followed by high temperature carbonization. This hierarchical network serves as a new class of catalyst support to enhance the activity and durability of noble metal catalysts for alcohol oxidation reactions. Its supported Pd nanoparticles, Pd/(Pd-CeO2@C CSNWN), exhibit >9 fold increase in activity toward the ethanol oxidation over the state-of-the-art Pd/C catalyst, which is the highest among the reported Pd systems. Moreover, stability tests show a virtually unchanged activity after 1000 cycles. The high activity is mainly attributed to the superior oxygen-species releasing capability of Pd-doped CeO2 nanowires by accelerating the removal of the poisoning intermediate. The unique

  8. Association between silent embolic cerebral infarction and continuous increase of P2Y12 reaction units after neurovascular stenting.

    Science.gov (United States)

    Kim, Bum Joon; Kwon, Joo Y; Jung, Jin-Man; Lee, Deok Hee; Kang, Dong-Wha; Kim, Jong S; Kwon, Sun U

    2014-10-01

    Endovascular procedures are one of the important treatment options for steno-occlusive arteries in ischemic stroke patients. However, embolic complications after such procedures are always a concern. The authors investigated the association between serial change of residual platelet reactivity and silent embolic cerebral infarction (SECI) after endovascular treatment. Ischemic stroke patients undergoing stenting of intra- or extracranial arteries were recruited prospectively. Residual platelet reactivity, represented by aspirin reaction units (ARUs) and P2Y12 reaction units (PRUs), was measured serially (6 hours before, immediately after, and 24 hours after the procedure). A loading dosage of aspirin (500 mg) and/or clopidogrel (300 mg) was given 24 hours before the procedure to patients naïve to antiplatelet agents, whereas the usual dosage (aspirin 100 mg and clopidogrel 75 mg) was continued for patients who had previously been taking these agents for more than a week. Diffusion-weighted MRI was performed before and 24 hours after the procedure to detect new SECIs. Clinical characteristics, baseline ARU and PRU values, and the change in ARU and PRU values after stenting were compared between patients with and without SECIs. Among 69 consecutive patients who underwent neurovascular stent insertion, 41 patients (59.4%) had poststenting SECIs. The lesion was located only at the vascular territory of the stented vessel in 21 patients (51.2%), outside the stented vessel territory in 8 patients (19.5%), and both inside and outside in 12 patients (29.3%). The occurrence of SECIs was not associated with the baseline ARU or PRU value, but was associated with PRU increase after stenting (36 ± 73 vs -12 ± 59, p = 0.007), deployment of a longer stent (31.1 ± 16.5 mm vs 21.8 ± 9.9 mm, p = 0.01), and stent insertion in extracranial arteries (78.1% vs 45.2%, p = 0.008). Stent length (OR 1.066, p = 0.01) and PRU change (OR 1.009, p = 0.04) were independently associated with

  9. Carbon-Encapsulated Co3O4@CoO@Co Nanocomposites for Multifunctional Applications in Enhanced Long-life Lithium Storage, Supercapacitor and Oxygen Evolution Reaction

    International Nuclear Information System (INIS)

    Xu, Dongyang; Mu, Congpu; Xiang, Jianyong; Wen, Fusheng; Su, Can; Hao, Chunxue; Hu, Wentao; Tang, Yongfu; Liu, Zhongyuan

    2016-01-01

    Porous nanostructure composites materials had attracted widely attention due to their potential application in energy storage (Lithium ion batteries (LIBs) and supercapacitor) and electrocatalyst of oxygen evolution reaction (OER). Co 3 O 4 @CoO@Co@C nanocomposites had been successfully synthesized using glucose as carbon source and cobalt nitrate as metalprecurs or of Co 3 O 4 @CoO@Co@C, which has excellent electrochemical performance for LIBs, supercapacitor and OER. Three kinds of morphology samples marked by Co 3 O 4 @CoO@Co@C-2/1, Co 3 O 4 @CoO@Co@C-1/1 and Co 3 O 4 @CoO@Co@C-1/2 are synthesized due to different atomic ratio of cobalt/carbon in precursors. Electrochemical and catalytic performance of Co 3 O 4 @CoO@Co@C-2/1 nanocomposites is more excellent than Co 3 O 4 @CoO@Co@C-1/1 and Co 3 O 4 @CoO@Co@C-1/2. Co 3 O 4 @CoO@Co@C-2/1 shows that discharge capacity can maintain 450 mA h g −1 and coulombic efficiency is nearly 100% during 500 cycles for LIBs. It indicates the excellent cycling stability of Co 3 O 4 @CoO@Co@C-2/1 as electrode for supercapacitor that about 78.3% of initial specific capacitance can be retained after 10000 cycles at current density of 2 A g −1 . Co 3 O 4 @CoO@Co@C-2/1 as catalyst of OER shows excellent electrochemical durability over 15 hours continuous experiment.

  10. Fossil and Contemporary Fine Carbon Fractions at 12 Rural and Urban Sites in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Schichtel, B; Malm, W; Bench, G; Fallon, S; McDade, C; Chow, J

    2007-03-01

    Fine particulate matter collected at two urban, four near-urban, and six remote sites throughout the United States were analyzed for total carbon (TC) and radiocarbon ({sup 14}C). Samples were collected at most sites for both a summer and winter season. The radiocarbon was used to partition the TC into fossil and contemporary fractions. On average, contemporary carbon composed about half of the carbon at the urban, {approx}70-97% at near-urban, and 82-100% at remote sites. At Phoenix, Arizona, and Seattle, Washington, one monitor was located within the urban center and one outside to assess the urban excess over background concentrations. During the summer the urban and rural sites had similar contemporary carbon concentrations. However, during the winter the urban sites had more than twice the contemporary carbon measured at the neighboring sites, indicating anthropogenic contributions to the contemporary carbon. The urban fossil carbon was 4-20 times larger than the neighboring rural sites for both seasons. Organic (OC) and elemental carbon (EC) from TOR analysis were available. These and the radiocarbon data were used to estimate characteristic fossil and contemporary EC/TC ratios for the winter and summer seasons. These ratios were applied to carbon data from the Interagency Monitoring of Protected Visual Environments network to estimate the fraction of contemporary carbon at mostly rural sites throughout the United States. In addition, the ratios were used to develop a semiquantitative, lower bound estimate of secondary organic carbon (SOC) contribution to fossil and contemporary carbon. SOC accounted for more than one-third of the fossil and contemporary carbon.

  11. The Exchange Reaction Between Methane Hydrate and Carbon Dioxide: An Oceanic Feasibility Test

    Science.gov (United States)

    Dunk, R. M.; Brewer, P. G.; Peltzer, E. T.; Walz, P. M.; Hester, K. C.; Sloan, E. D.

    2006-12-01

    The conversion of CH4 hydrate to CO2 hydrate offers, in principle, a way of sequestering CO2, with the additional recovery of CH4 gas as an energy source. We report results from the first in-situ oceanic experiment on this reaction, carried out in August 2006 at the massive thermogenic hydrate mounds in 850 m water depth, Barkley Canyon, offshore from Vancouver Island (48° 18.642' N, 126° 3.903' W), using MBARI's ROV Tiburon deployed from the R/V Western Flyer. Two small cores (10 cm length, 4 cm diameter) of white hydrate were collected from exposed outcrops using an ROV operated tool and hydraulically ejected into a glass walled, closed top, reaction chamber. Approximately 2 L of liquid CO2 were dispensed into the chamber, and the chamber transferred to an aluminium base plate to seal the system. Under ambient conditions (P = 870 dbar, T = 4.0 °C, S = 34.2), the densities of natural gas hydrate and liquid CO2 are closely matched and less than that of seawater, where the hydrate cores floated at the top of the chamber fully immersed within the buoyant liquid CO2. Over the following ~48 hours, the system was inspected periodically with the ROV HDTV camera prior to examination with the sea-going laser Raman spectrometer, DORISS II. For this, the chamber was transferred to a Precision Underwater Positioner (PUP) that enabled focusing of the laser beam with sub- mm precision. Our choice of where to focus the laser was based upon the need to explore all phases the cored natural gas hydrate, liquid CO2, any created CO2 hydrate, and any liberated CH4 gas. The natural gas hydrate was composed primarily of CH4, with minor amounts of C2H6 and C3H8, indicating the presence of Structure II hydrate. To date, laboratory experiments have focused on the reaction between pure Structure I CH4 hydrate and CO2 vapour, where the difference in free energy between the CH4 and CO2 hydrate states provides a thermodynamic argument in favour of conversion. However for a Structure II

  12. Relationships between Static and Dynamic Balance and Anticipation Time, Reaction Time in School Children at the Age of 10-12 Years

    Science.gov (United States)

    Bozkurt, Sinan; Erkut, Oya; Akkoç, Orkun

    2017-01-01

    The aim of this study is to investigate the relationship between anticipation time, reaction time and balance characteristics in school children at the age of 10-12 years. 11 males and 12 females, 23 students in total, studying at Istanbul Sancaktepe Ibn-i Sina Elementary School, whose average age was 11.06 years, average height was 142.78 cm and…

  13. Experimental study of bound states in 12Be through low-energy 11Be(d,p)-transfer reactions

    DEFF Research Database (Denmark)

    Johansen, Jacob S.; Bildstein, V.; Borge, M. J. G.

    2013-01-01

    The bound states of 12Be have been studied through a 11Be(d,p)12Be transfer reaction experiment in inverse kinematics. A 2.8 MeV/u beam of 11Be was produced using the REX-ISOLDE facility at CERN. The outgoing protons were detected with the T-REX silicon detector array. The MINIBALL germanium arra...

  14. A Study of the Abundance and 13C/12C Ratio of Atmospheric Carbon Dioxide to Advance the Scientific Understanding of Terrestrial Processes Regulating the Global Carbon Cycle

    Energy Technology Data Exchange (ETDEWEB)

    Stephen C. Piper

    2005-10-15

    The primary goal of our research program, consistent with the goals of the U.S. Climate Change Science Program and funded by the terrestrial carbon processes (TCP) program of DOE, has been to improve understanding of changes in the distribution and cycling of carbon among the active land, ocean and atmosphere reservoirs, with particular emphasis on terrestrial ecosystems. Our approach is to systematically measure atmospheric CO2 to produce time series data essential to reveal temporal and spatial patterns. Additional measurements of the 13C/12C isotopic ratio of CO2 provide a basis for distinguishing organic and inorganic processes. To pursue the significance of these patterns further, our research also involved interpretations of the observations by models, measurements of inorganic carbon in sea water, and of CO2 in air near growing land plants.

  15. From melamine sponge towards 3D sulfur-doping carbon nitride as metal-free electrocatalysts for oxygen reduction reaction

    Science.gov (United States)

    Xu, Jingjing; Li, Bin; Li, Songmei; Liu, Jianhua

    2017-07-01

    Development of new and efficient metal-free electrocatalysts for replacing Pt to improve the sluggish kinetics of oxygen reduction reaction (ORR) is of great importance to emerging renewable energy technologies such as metal-air batteries and polymer electrolyte fuel cells. Herein, 3D sulfur-doping carbon nitride (S-CN) as a novel metal-free ORR electrocatalyst was synthesized by exploiting commercial melamine sponge as raw material. The sulfur atoms were doping on CN networks uniformly through numerous S-C bonds which can provide additional active sites. And it was found that the S-CN exhibited high catalytic activity for ORR in term of more positive onset potential, higher electron transfer number and higher cathodic density. This work provides a novel choice of metal-free ORR electrocatalysts and highlights the importance of sulfur-doping CN in metal-free ORR electrocatalysts.

  16. Co@Co3O4 nanoparticle embedded nitrogen-doped carbon architectures as efficient bicatalysts for oxygen reduction and evolution reactions

    Science.gov (United States)

    Qi, Chunling; Zhang, Li; Xu, Guancheng; Sun, Zhipeng; Zhao, Aihua; Jia, Dianzeng

    2018-01-01

    The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play crucial roles in efficient energy conversion and storage solutions. Here, Co@Co3O4 nanoparticle embedded nitrogen-doped carbon architectures (denoted as Co@Co3O4/NCs) are prepared via a simple two-step and in situ approach by carbonization and subsequent oxidation of Co-MOF containing high contents of carbon and nitrogen. When evaluated as electrocatalyst towards both ORR and OER in a KOH electrolyte solution, the as-fabricated Co@Co3O4/NC-2 exhibits similar ORR catalytic activity to the commercial Pt/C catalyst, but superior stability and good methanol tolerance. Furthermore, the as-fabricated catalysts also show promising catalytic activity for OER. The effective catalytic activities originate from the synergistic effects between well wrapped Co@Co3O4 nanoparticles and nitrogen doped carbon structures.

  17. Electrochemical Deposition of Platinum and Palladium on Gold Nanoparticles Loaded Carbon Nanotube Support for Oxidation Reactions in Fuel Cell

    Directory of Open Access Journals (Sweden)

    Surin Saipanya

    2014-01-01

    Full Text Available Pt and Pd sequentially electrodeposited Au nanoparticles loaded carbon nanotube (Au-CNT was prepared for the electrocatalytic study of methanol, ethanol, and formic acid oxidations. All electrochemical measurements were carried out in a three-electrode cell. A platinum wire and Ag/AgCl were used as auxiliary and reference electrodes, respectively. Suspension of the Au-CNT, phosphate buffer, isopropanol, and Nafion was mixed and dropped on glassy carbon as a working electrode. By sequential deposition method, PdPtPt/Au-CNT, PtPdPd/Au-CNT, and PtPdPt/Au-CNT catalysts were prepared. Cyclic voltammograms (CVs of those catalysts in 1 M H2SO4 solution showed hydrogen adsorption and hydrogen desorption reactions. CV responses for those three catalysts in methanol, ethanol, and formic acid electrooxidations studied in 2 M CH3OH, CH3CH2OH, and HCOOH in 1 M H2SO4 show characteristic oxidation peaks. The oxidation peaks at anodic scan contribute to those organic substance oxidations while the peaks at cathodic scan are related with the reoxidation of the adsorbed carbonaceous species. Comparing all those three catalysts, it can be found that the PdPtPt/Au-CNT catalyst is good at methanol oxidation; the PtPdPt/Au-CNT effectively enhances ethanol oxidation while the PtPdPd/Au-CNT exceptionally catalyzes formic acid oxidation. Therefore, a different stoichiometry affects the electrochemical active surface area of the catalysts to achieve the catalytic oxidation reactions.

  18. (π±, π±' N) reactions on 12C and 208Pb near the giant resonance region

    International Nuclear Information System (INIS)

    Yoo, Sung Hoon.

    1990-05-01

    Angular distributions for the 12 C(π ± , π ± ' p) and 208 Pb(π ± , π ± ' p or n) reactions near the giant resonance region have been measured at T π = 180 MeV, and found different between π + and π - data. This observation is interpreted as evidence for different excitation mechanisms dominating the π - -nucleus and π + -nucleus interactions in the giant resonance region of these targets. A comparison with the single-nucleon knock-out distorted-wave impulse approximation calculations shows, even though these calculations underestimate (π ± , π ± ' N) data for both targets, the dominance of direct process for (π + , π + ' p) or (π - , π - ' n) in contrast to (π - , π - ' p) or (π + , π + ' n). In the (π + , π + ' p) reaction proton-proton hole states are excited directly and appear to have a large probability for direct decay with escape width, whereas in (π - , π - ' p) the preferentially excited neutron-neutron hole doorway states couple to resonance states and decay with spreading width. This interpretation led us to suggest that the ratio of cross-sections for inelastic scattering to the giant resonance region should be written in terms of an incoherent sum of cross-sections to neutron and proton doorway states. In a heavy nucleus such as 208 Pb, neutron and proton doorway states. In a heavy nucleus such as 208 Pb, neutron and proton doorway states contribute incoherently because the different decay processes do not populate the same final states of the residual nucleus

  19. Transition Metal Catalyzed Reactions for Forming Carbon–Oxygen and Carbon–Carbon Bonds

    DEFF Research Database (Denmark)

    Sølvhøj, Amanda Birgitte

    , using the radical precursor as solvent, in the presence of 10–12 % of MnCl2, and refluxing overnight in the presence of air. A simple acidic workup and purification by chromatography yielded the products in moderate to good yield. The radical precursor can be a cyclic or acyclic ether or even...

  20. Identification of catalytic sites in cobalt-nitrogen-carbon materials for the oxygen reduction reaction

    Czech Academy of Sciences Publication Activity Database

    Zitolo, A.; Ranjbar-Sahraie, N.; Mineva, T.; Li, J.; Jia, J.; Stamatin, Serban; Harrington, G. F.; Lyth, S. M.; Krtil, Petr; Mukerjee, S.; Fonda, E.; Jaouen, F.

    2017-01-01

    Roč. 8, č. 1 (2017), č. článku 957. ISSN 2041-1723 Institutional support: RVO:61388955 Keywords : ray-absorption spectroscopy * density-functional theory * body distribution-functions * electrolyte fuel -cells Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 12.124, year: 2016

  1. Composite of TiN nanoparticles and few-walled carbon nanotubes and its application to the electrocatalytic oxygen reduction reaction

    KAUST Repository

    Isogai, Shunsuke

    2011-11-30

    Nanoparticles meet nanotubes! Direct synthesis of TiN nanoparticles in a three-dimensional network of few-walled carbon nanotubes (FWCNTs) was achieved by using mesoporous graphitic carbon nitride (C 3N 4) as both a hard template and a nitrogen source. The TiN/FWCNT composite showed high performance for the oxygen reduction reaction in acidic media. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Functionalization of multi-walled carbon nanotubes with iron phthalocyanine via a liquid chemical reaction for oxygen reduction in alkaline media

    Science.gov (United States)

    Yan, Xiaomei; Xu, Xiao; Liu, Qin; Guo, Jia; Kang, Longtian; Yao, Jiannian

    2018-06-01

    Iron single-atom catalyst in form of iron-nitrogen-carbon structure possesses the excellent catalytic activity in various chemical reactions. However, exploring a sustainable and stable single-atom metal catalyst still faces a great challenge due to low yield and complicated synthesis. Here, we report a functional multi-wall carbon nanotubes modified with iron phthalocyanine molecules via a liquid chemical reaction and realize the performance of similar single-atom catalysis for oxygen reduction reaction. A serial of characterizations strongly imply the structure change of iron phthalocyanine molecule and its close recombination with multi-wall carbon nanotubes, which are in favor of ORR catalysis. Compared to commercial platinum-carbon catalyst, composites exhibit superior activity for oxygen reduction reaction with higher half-wave potential (0.86 V), lower Tafel slope (38 mV dec-1), higher limiting current density and excellent electrochemical stability. The corresponding Zinc-air battery also presents higher maximum power density and discharge stability. Therefore, these findings provide a facile route to synthesize a highly efficient non-precious metal carbon-based catalyst.

  3. Improving biomass-derived carbon by activation with nitrogen and cobalt for supercapacitors and oxygen reduction reaction

    Science.gov (United States)

    Zhang, Man; Jin, Xin; Wang, Linan; Sun, Mengjia; Tang, Yang; Chen, Yongmei; Sun, Yanzhi; Yang, Xiaojin; Wan, Pingyu

    2017-07-01

    Biomass-derived carbon by activation with nitrogen and cobalt (denoted as NPACCo) was prepared by one-pot pyrolysis of pomelo peel with melamine, cobalt nitrate and potassium hydroxide, followed by acid leaching. NPACCo possesses high content of quaternary-N (2.5%) and pyridinic-N (1.7%), co-existences of amorphous and short-range ordered carbon, high specific surface area and pore structure with majority of micropores and small mesopores. As electrode material of supercapacitors, NPACCo exhibits high specific capacitance and good rate capability. At ultrahigh rate of 50 A g-1 (135 mA cm-2), the capacitance of NPACCo remains 246 F g-1, which is 6.3, 1.9 and 3.2 times as high as that of other three materials (PC, PAC and NPAC). The as-assembled symmetric supercapacitor of NPACCo delivers high energy density, high power density and excellent cycling stability. With respect to oxygen reduction reaction (ORR), NPACCo exhibits high onset potential (0.87 V), high half-wave potential (0.78 V), excellent methanol tolerance and low yield of H2O2. The ORR properties of NPACCo are comparable or superior to those of commercial Pt/C. This investigation of pomelo peel-based NPACCo would be valuable for development of both supercapacitor and ORR.

  4. Fe Isolated Single Atoms on S, N Codoped Carbon by Copolymer Pyrolysis Strategy for Highly Efficient Oxygen Reduction Reaction.

    Science.gov (United States)

    Li, Qiheng; Chen, Wenxing; Xiao, Hai; Gong, Yue; Li, Zhi; Zheng, Lirong; Zheng, Xusheng; Yan, Wensheng; Cheong, Weng-Chon; Shen, Rongan; Fu, Ninghua; Gu, Lin; Zhuang, Zhongbin; Chen, Chen; Wang, Dingsheng; Peng, Qing; Li, Jun; Li, Yadong

    2018-06-01

    Heteroatom-doped Fe-NC catalyst has emerged as one of the most promising candidates to replace noble metal-based catalysts for highly efficient oxygen reduction reaction (ORR). However, delicate controls over their structure parameters to optimize the catalytic efficiency and molecular-level understandings of the catalytic mechanism are still challenging. Herein, a novel pyrrole-thiophene copolymer pyrolysis strategy to synthesize Fe-isolated single atoms on sulfur and nitrogen-codoped carbon (Fe-ISA/SNC) with controllable S, N doping is rationally designed. The catalytic efficiency of Fe-ISA/SNC shows a volcano-type curve with the increase of sulfur doping. The optimized Fe-ISA/SNC exhibits a half-wave potential of 0.896 V (vs reversible hydrogen electrode (RHE)), which is more positive than those of Fe-isolated single atoms on nitrogen codoped carbon (Fe-ISA/NC, 0.839 V), commercial Pt/C (0.841 V), and most reported nonprecious metal catalysts. Fe-ISA/SNC is methanol tolerable and shows negligible activity decay in alkaline condition during 15 000 voltage cycles. X-ray absorption fine structure analysis and density functional theory calculations reveal that the incorporated sulfur engineers the charges on N atoms surrounding the Fe reactive center. The enriched charge facilitates the rate-limiting reductive release of OH* and therefore improved the overall ORR efficiency. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Synthesis of a highly active carbon-supported Ir-V/C catalyst for the hydrogen oxidation reaction in PEMFC

    International Nuclear Information System (INIS)

    Li Bing; Qiao Jinli; Yang Daijun; Zheng Junsheng; Ma Jianxin; Zhang Jiujun; Wang Haijiang

    2009-01-01

    The active, carbon-supported Ir and Ir-V nanoclusters with well-controlled particle size, dispersity, and composition uniformity, have been synthesized via an ethylene glycol method using IrCl 3 and NH 4 VO 3 as the Ir and V precursors. The nanostructured catalysts were characterized by X-ray diffraction and high-resolution transmission electron microscopy. The catalytic activities of these carbon-supported nanoclusters were screened by applying on-line cyclic voltammetry and electrochemical impedance spectroscopy techniques, which were used to characterize the electrochemical properties of fuel cells using several anode Ir/C and Ir-V/C catalysts. It was found that Ir/C and Ir-V/C catalysts affect the performance of electrocatalysts significantly based on the discharge characteristics of the fuel cell. The catalyst Ir-V/C at 40 wt.% displayed the highest catalytic activity to hydrogen oxidation reaction and, therefore, high cell performance is achieved which results in a maximum power density of 563 mW cm -2 at 0.512 V and 70 deg. C in a real H 2 /air fuel cell. This performance is 20% higher as compared to the commercial available Pt/C catalyst. Fuel cell life test at a constant current density of 1000 mA cm -2 in a H 2 /O 2 condition shows good stability of anode Ir-V/C after 100 h of continuous operation.

  6. Carbon Supported Engineering NiCo2O4 Hybrid Nanofibers with Enhanced Electrocatalytic Activity for Oxygen Reduction Reaction

    Directory of Open Access Journals (Sweden)

    Diab Hassan

    2016-09-01

    Full Text Available The design of cheap and efficient oxygen reduction reaction (ORR electrocatalysts is of a significant importance in sustainable and renewable energy technologies. Therefore, ORR catalysts with superb electrocatalytic activity and durability are becoming a necessity but still remain challenging. Herein, we report C/NiCo2O4 nanocomposite fibers fabricated by a straightforward electrospinning technique followed by a simple sintering process as a promising ORR electrocatalyst in alkaline condition. The mixed-valence oxide can offer numerous accessible active sites. In addition, the as-obtained C/NiCo2O4 hybrid reveals significantly remarkable electrocatalytic performance with a highly positive onset potential of 0.65 V, which is only 50 mV lower than that of commercially available Pt/C catalysts. The analyses indicate that C/NiCo2O4 catalyst can catalyze O2-molecules via direct four electron pathway in a similar behavior as commercial Pt/C catalysts dose. Compared to single NiCo2O4 and carbon free NiCo2O4, the C/NiCo2O4 hybrid displays higher ORR current and more positive half-wave potential. The incorporated carbon matrices are beneficial for fast electron transfer and can significantly impose an outstanding contribution to the electrocatalytic activity. Results indicate that the synthetic strategy hold a potential as efficient route to fabricate highly active nanostructures for practical use in energy technologies.

  7. Rational Design of Single Molybdenum Atoms Anchored on N-Doped Carbon for Effective Hydrogen Evolution Reaction.

    Science.gov (United States)

    Chen, Wenxing; Pei, Jiajing; He, Chun-Ting; Wan, Jiawei; Ren, Hanlin; Zhu, Youqi; Wang, Yu; Dong, Juncai; Tian, Shubo; Cheong, Weng-Chon; Lu, Siqi; Zheng, Lirong; Zheng, Xusheng; Yan, Wensheng; Zhuang, Zhongbin; Chen, Chen; Peng, Qing; Wang, Dingsheng; Li, Yadong

    2017-12-11

    The highly efficient electrochemical hydrogen evolution reaction (HER) provides a promising pathway to resolve energy and environment problems. An electrocatalyst was designed with single Mo atoms (Mo-SAs) supported on N-doped carbon having outstanding HER performance. The structure of the catalyst was probed by aberration-corrected scanning transmission electron microscopy (AC-STEM) and X-ray absorption fine structure (XAFS) spectroscopy, indicating the formation of Mo-SAs anchored with one nitrogen atom and two carbon atoms (Mo 1 N 1 C 2 ). Importantly, the Mo 1 N 1 C 2 catalyst displayed much more excellent activity compared with Mo 2 C and MoN, and better stability than commercial Pt/C. Density functional theory (DFT) calculation revealed that the unique structure of Mo 1 N 1 C 2 moiety played a crucial effect to improve the HER performance. This work opens up new opportunities for the preparation and application of highly active and stable Mo-based HER catalysts. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. PtRu nanoparticles dispersed on nitrogen-doped carbon nanohorns as an efficient electrocatalyst for methanol oxidation reaction

    International Nuclear Information System (INIS)

    Zhang, Linwei; Gao, Ang; Liu, Yan; Wang, Yuan; Ma, Jiantai

    2014-01-01

    Highlights: • A novel anode catalyst is synthesized using N-doped carbon nanohorns as support. • PtRu/NCNHs exhibits an excellent activity for MOR relative to PtRu/C catalysts. • The enhancement is due to the electronic interaction between NCNHs and PtRu NPs. - Abstract: A novel anode catalyst (PtRu/NCNHs) assembled with nitrogen-doped carbon nanohorns (NCNHs) and PtRu nanoparticles (1.9 nm) exhibits an obvious enhancement in the tolerance to carbonaceous intermediates and the electocatalytic activity for methanol oxidation reaction (MOR) in comparison to a commercial PtRu/C-JM catalyst and a home-made PtRu/Vulcan catalyst. The MOR mass activity of PtRu/NCNHs (850 mA mg −1 PtRu ) is 2.5 times as high as that of PtRu/C-JM (341 mA mg −1 PtRu ). The MOR specific activity of PtRu/NCNHs is 1.8 times as high as that of PtRu/Vulcan having similar Pt/Ru atomic ratios, specific electrochemical surface areas and particle sizes of PtRu NPs. The electronic interaction between PtRu NPs and NCNHs is responsible for the enhancement in the MOR activity of PtRu/NCNHs

  9. Tungsten carbide encapsulated in nitrogen-doped carbon with iron/cobalt carbides electrocatalyst for oxygen reduction reaction

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jie; Chen, Jinwei, E-mail: jwchen@scu.edu.cn; Jiang, Yiwu; Zhou, Feilong; Wang, Gang; Wang, Ruilin, E-mail: rl.wang@scu.edu.cn

    2016-12-15

    Graphical abstract: A hybrid catalyst was prepared via a quite green and simple method to achieve an one-pot synthesis of the N-doping carbon, tungsten carbides, and iron/cobalt carbides. It exhibited comparable electrocatalytic activity, higher durability and ability to methanol tolerance compared with commercial Pt/C to ORR. - Highlights: • A novel type of hybrid Fe/Co/WC@NC catalysts have been successfully synthesized. • The hybrid catalyst also exhibited better durability and methanol tolerance. • Multiple effective active sites of Fe{sub 3}C, Co{sub 3}C, WC, and NC help to improve catalytic performance. - Abstract: This work presents a type of hybrid catalyst prepared through an environmental and simple method, combining a pyrolysis of transition metal precursors, a nitrogen-containing material, and a tungsten source to achieve a one-pot synthesis of N-doping carbon, tungsten carbides, and iron/cobalt carbides (Fe/Co/WC@NC). The obtained Fe/Co/WC@NC consists of uniform Fe{sub 3}C and Co{sub 3}C nanoparticles encapsulated in graphitized carbon with surface nitrogen doping, closely wrapped around a plate-like tungsten carbide (WC) that functions as an efficient oxygen reduction reaction (ORR) catalyst. The introduction of WC is found to promote the ORR activity of Fe/Co-based carbide electrocatalysts, which is attributed to the synergistic catalysts of WC, Fe{sub 3}C, and Co{sub 3}C. Results suggest that the composite exhibits comparable electrocatalytic activity, higher durability, and ability for methanol tolerance compared with commercial Pt/C for ORR in alkaline electrolyte. These advantages make Fe/Co/WC@NC a promising ORR electrocatalyst and a cost-effective alternative to Pt/C for practical application as fuel cell.

  10. N-Doped Carbon Nanofibrous Network Derived from Bacterial Cellulose for the Loading of Pt Nanoparticles for Methanol Oxidation Reaction.

    Science.gov (United States)

    Yuan, Fanshu; Huang, Yang; Fan, Mengmeng; Chen, Chuntao; Qian, Jieshu; Hao, Qingli; Yang, Jiazhi; Sun, Dongping

    2018-02-06

    The large-scale, low-cost preparation of Pt-based catalysts with high activity and durability for the methanol oxidation reaction is still challenging. The key to achieving this aim is finding suitable supporting materials. In this paper, N-doped carbon nanofibrous networks are prepared by annealing a gel containing two inexpensive and ecofriendly precursors, that is, bacterial cellulose and urea, for the loading of Pt nanoparticles. An undoped analogue is also prepared for comparison. Meanwhile, the effect of the annealing temperature on the performance of the catalysts is evaluated. The results show that the N doping and higher annealing temperature can improve the electron conductivity of the catalyst and provide more active sites for the loading of ultrafine Pt nanoparticles with a narrow size distribution. The best catalyst exhibits a remarkably high electrocatalytic activity (627 mA mg -1 ), excellent poison tolerance, and high durability. This work demonstrates an ideal Pt supporting material for the methanol oxidation reaction. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. The quantitative monitoring of mechanochemical reaction between solid L-tartaric acid and sodium carbonate monohydrate by terahertz spectroscopy

    Science.gov (United States)

    Liu, Xiaohong; Liu, Guifeng; Zhao, Hongwei; Zhang, Zengyang; Wei, Yongbo; Liu, Min; Wen, Wen; Zhou, Xingtai

    2011-11-01

    The solid-state reaction of chiral tartaric acid and alkali carbonate was studied by terahertz time-domain spectroscopy (THz-TDS). The sodium tartrate dihydrate was synthesized with high efficiency by mechanical grinding in the solid-state without waste that is particularly sustainable and environmentally benign. Distinct THz absorptions were observed for reactants and products. It indicates that THz spectroscopy is sensitive to different materials and crystal structures. The characteristic THz absorption peak at 1.09 THz of L (+)-Tartaric acid was selected for quantitative analysis. The reaction kinetics could be expressed by the Second-order equation and the Jander equation, which is consistent with a three-dimensional diffusion mechanism. The combination of multi-techniques including synchrotron radiation X-ray powder diffraction (SRXRPD), Fourier transform infrared (FT-IR) and scanning electron microscopy (SEM) was used to investigate the grinding process and presented supporting evidences. The results demonstrate that THz spectroscopy technique has great potential applications in process monitoring and analysis in pharmaceutical and chemical synthesis industry.

  12. Enantioselective organocatalyzed Oxa-Michael-Aldol cascade reactions: Construction of chiral 4H-chromenes with a trifluoromethylated tetrasubstituted carbon stereocenter

    KAUST Repository

    Zhang, Jing

    2015-03-13

    The first organocatalytic asymmetric synthesis of 4H-chromenes bearing a trifluoromethylated tetrasubstituted carbon center is presented. Chiral secondary amines promote the oxa-Michael-aldol cascade reaction between alkynals and 2-trifluoroacetylphenols via iminium-allenamine activation to produce pharmaceutically important heterocycles with excellent enantioselectivities. The proposed reaction can be scaled-up easily with maintenance of the excellent enantioselectivity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. 40 CFR 600.208-12 - Calculation of FTP-based and HFET-based fuel economy and carbon-related exhaust emission values...

    Science.gov (United States)

    2010-07-01

    ...-based fuel economy and carbon-related exhaust emission values for a model type. 600.208-12 Section 600... ECONOMY AND CARBON-RELATED EXHAUST EMISSIONS OF MOTOR VEHICLES Fuel Economy Regulations for 1977 and Later...-based and HFET-based fuel economy and carbon-related exhaust emission values for a model type. (a) Fuel...

  14. Dissolved Organic Carbon Determination Using FIA and Photo-Fenton Reaction

    Directory of Open Access Journals (Sweden)

    Márcia M. Kondo

    2002-03-01

    Full Text Available The FIA-photo-Fenton system is based on the flow oxidation of the organic matter. A small amount of the sample containing H2O2 is injected into the acidic flow solution of Fe2+, which passes through a tubular PTFE reactor irradiated with UV light. The generated CO2 is quantified by a conductometric detector and is directly proportional to the dissolved organic carbon concentration in the sample. The optimization studies were performed using EDTA solutions. The average recovery of organic carbon was 83% with a relative standard deviation of 3.7% using a 1:5 molar ratio of Fe2+:H2O2, pH 2.0, 100 muL of sample injection and a liquid flow of 1 mL min-1. After optimization, the DOC concentration was quantified using 13 different organic compounds, where the average recovery was 90%. The rate of the analysis was in average 50 samples hour-1.O sistema FIA-foto-Fenton é baseado na oxidação em fluxo da matéria orgânica. Uma pequena quantidade de amostra contendo H2O2 é introduzida no fluxo de uma solução ácida de Fe2+, que passa por um reator tubular de PTFE irradiado com luz UV. O CO2 gerado é quantificado condutometricamente e é diretamente proporcional à concentração de carbono orgânico dissolvido na amostra. Os estudos de otimização foram realizados empregando soluções de EDTA. A recuperação média de carbono orgânico foi de 83% com desvio padrão relativo de 3,7% empregando 100 miL de amostra, pH 2,0, razão molar entre Fe2+ e H2O2 de 1:5 e uma vazão de 1 mL.min-1. Após otimização as concentrações de DOC foram quantificadas em 13 diferentes compostos orgânicos, com uma recuperação média de 90%. A velocidade de análise foi em média 50 amostras/h.

  15. Catalytic activity in reactions of isotopic exchange of carbon monoxide and adsorption properties of catalysts on zinc oxide base

    International Nuclear Information System (INIS)

    Mikheeva, T.M.; Kasatkina, L.A.; Volynkina, A.Ya.

    1987-01-01

    Activity of different zinc oxide samples in reaction of CO homomolecular isotopic exchnge (HMIE) ( 13 C 18 O+ 12 C 16 O= 13 C 16 O+ 12 C 18 O), CO adsorption on ZnO and isotopic exchange between adsorbed and gaseous CO are investigated. The most active is ZnO sample prepared from ZnCO 3 . Quantitative ratio between different with respect to surface strength molecules of adsorbed CO are experimentally determined. It is shown that by increase of ZnO time contact with CO the quantity of adsorbed CO(N σ/0 ), capable of fast exchange with a gaseous phase, is reduced and the quantity of slowly exchanged adsorbed CO is increased. Correlation between decrease of N σ/0 and decrease of CO HMIE with the catalyst holding time in CO medium is stated

  16. Study on the distribution of organic carbon in soil fractions and its reaction potential of binding the pesticides

    Science.gov (United States)

    Chowdhury, Ashim

    2010-05-01

    STUDY ON THE DISTRIBUTION OF ORGANIC CARBON IN SOIL FRACTIONS AND ITS REACTION POTENTIAL OF BINDING THE PESTICIDES **SUMITRA ROY1, SANKHAJIT ROY1, *ASHIM CHOWDHURY2, SASWATI PRADHAN2 and PETER BURAUEL3 1Department of Agricultural Chemicals, Bidhan Chandra Krishi Viswavidyalay, Mohanpur, West Bengal, India. 2Department of Agricultural Chemistry and Soil Science, University of Calcutta, West Bengal, India. 3Institute of Chemical Dynamics & Geosphere, FZ-Juelich, Germany. *Correspondence: ashimkly@hotmail.com **Research work carried out as DAAD Sandwich research fellow at FZ- Juelich, Germany Soil is the ultimate sink of all selectively applied pesticides. In addition to the basic physicochemical data of an active ingredient, the fate of the various compounds is largely determined by the type of application. Finally, pesticide and their metabolites, as well as structural elements, remain in the native carbon reserves of the soil or are sorbed & fixed to clay minerals and clay- humus complexes. Soil organic matter (SOM) and the soil microbial community are the crucial components which regulate soil processes and contribute towards the stability of the soil ecosystem. It is an energy source for biological mineralization processes, functions as a buffer and participates in chemical reaction. Knowledge is essential to understand the extent to which the SOM influences the mobilization and immobilization processes of foreign substance in soil and the substance transport and pollutant decomposition in soil. The freshly incorporated organic matter undergoes mineralization and the non mineralized carbon fraction is of special relevance with respect to soil stability in general and decisive for the fate and particular the persistence of xenobiotics in soil. The biological and physicochemical interactions establishing equilibrium between the organic matter bound, fixed or complexed to the soil matrix and that dissolve in the soil solution must be understood in detail to realize

  17. One-pot, two-step synthesis of imidazo[1,2-a]benzimidazoles via a multicomponent [4 + 1] cycloaddition reaction.

    Science.gov (United States)

    Hsiao, Ya-Shan; Narhe, Bharat D; Chang, Ying-Sheng; Sun, Chung-Ming

    2013-10-14

    A one-pot, two-step synthesis of imidazo[1,2-a]benzimidazoles has been achieved by a three-component reaction of 2-aminobenzimidazoles with an aromatic aldehyde and an isocyanide. The reaction involving condensation of 2-aminobenzimidazole with an aldehyde is run under microwave activation to generate an imine intermediate under basic conditions which then undergoes [4 + 1] cycloaddition with an isocyanide.

  18. Analyzing power measurements for the rvec d+d→d+p+n breakup reaction at 12 MeV

    International Nuclear Information System (INIS)

    Felsher, P.D.; Howell, C.R.; Tornow, W.; Roberts, M.L.; Hanly, J.M.; Weisel, G.J.; Ohali, M.A.; Walter, R.L.; Slaus, I.; Lambert, J.M.; Treado, P.A.; Mertens, G.; Fonseca, A.C.; Soldi, A.; Vlahovic, B.

    1997-01-01

    We report the most extensive set of vector iT 11 and tensor T 20 and T 22 analyzing-power data for the rvec d+d→d+p+n reaction. Two-particle coincidence data have been measured for six deuteron-proton, three deuteron-neutron and three proton-neutron angle pairs at an incident deuteron energy of 12.0 MeV. These data are compared to impulse-approximation calculations that treat the underlying nucleon-deuteron system exactly and include contributions from both target and projectile breakup processes. This model gives a good description of the analyzing-power and relative cross-section data. We show that the inclusion of nucleon-nucleon P interactions considerably improves the agreement with the spin observables. The disagreement between the data and theoretical predictions show the limitations in our model and the importance of the rescattering processes. We suggest that the d+d three-body breakup process will provide useful information on the nucleon-nucleon force when exact calculations become available. copyright 1997 The American Physical Society

  19. Analyzing power measurements for the d+d-d+p+n breakup reaction at 12MeV

    International Nuclear Information System (INIS)

    Felsher, P.D.; Howell, C.R.; Tornow, W.; Roberts, M.L.; Hanly, J.K.; Weisel, G.J.; Ohali, M. Al; Walter, R.L.; Slaus, I.; Lambert, J.M.; Treado, P.A.; Mertens, G.; Fonseca, G.; Soldi, A.; Vlahovic, B.

    1997-01-01

    We report the most extensive set of vector iT11 and tensor T20 and T22 analyzing-power for the d=d-d=p=n reaction. Two-particle coincidence data have been measured for six deuteron-proton, three deuteron-neutron and three proton-neutron angle pairs at an incident deuteron energy of 12.0MeV. These data are compared to impulse-approximation calculations that threat the underlying nucleon-deuteron system exactly and include contributions from both target and projectile breakup processes. This model gives a good description of the analyzing-power and relative cross-section data. We show that the inclusion of nucleon-nucleon P interactions considerably improves the agreement with the spin observables. The disagreement between the data and theoretical predictions show the limitations in our model and the importance of the rescattering processes. We suggest that the d+d three-body breakup process will provide useful information on the nucleon-nucleon force when exact calculations become available. [S0556-2813(97)02907-5

  20. 16O resonances near the 4α threshold through the 12C(6Li,d) reaction

    Science.gov (United States)

    Rodrigues, M. R. D.; Borello-Lewin, T.; Miyake, H.; Duarte, J. L. M.; Rodrigues, C. L.; Souza, M. A.; Horodynski-Matsushigue, L. B.; Ukita, G. M.; Cappuzzello, F.; Cunsolo, A.; Cavallaro, M.; Agodi, C.; Foti, A.

    2014-02-01

    Background: Resonances around xα thresholds in light nuclei are recognized to be important in basic aspects of nuclear structure. However, there is scarce experimental information associated with them. Purpose: We study the α-clustering phenomenon in resonant states around the 4α threshold (14.44 MeV) in the 16O nucleus. Method: The 12C(6Li,d )16O reaction was investigated with an unprecedented resolution at a bombarding energy of 25.5 MeV by employing the São Paulo Pelletron-Enge-Spectrograph facility and the nuclear emulsion technique. Results: Several narrow resonances were populated and the energy resolution of 15 keV allows for the separation of doublet states that were not resolved previously. The upper limits for the resonance widths in this region were extracted. The angular distributions of the absolute differential cross section associated with four natural parity quasibound states are presented and compared to distorted wave Born approximation predictions. Conclusions: Narrow resonances not previously reported in the literature were observed. This indicates that the α-cluster structure information in this region should be revised.

  1. Kinetics and reaction mechanism for aminolysis of benzyl 4-pyridyl carbonate in H2O: Effect of modification of nucleofuge from 2-pyridyl oxide to 4-pyridyl oxide on reactivity and reaction mechanism

    International Nuclear Information System (INIS)

    Kang, Ji Sun; Um, Ikhwan

    2012-01-01

    Pseudo-first-order rate constants k amine have been measured spectrophotometrically for the reactions of benzyl 4-pyridyl carbonate 6 with a series of alicyclic secondary amines in H 2 O at 25.0.deg.C. The plots of k amine vs. [amine] curve upward, indicating that the reactions proceed through a stepwise mechanism with two intermediates, a zwitterionic tetrahedral intermediate T ± and its deprotonated form T - . This contrasts to the report that the corresponding reactions of benzyl 2-pyridyl carbonate 5 proceed through a forced concerted pathway. The k amine values for the reactions of 6 have been dissected into the second-order rate constant Kk 2 and the third order rate constant Kk 3 . The Brφnsted-type plots are linear with β nuc = 0.94 and 1.18 for Kk 2 and Kk 3 , respectively. The Kk 2 for the reaction of 6 is smaller than the second-order rate constant k N for the corresponding reaction of 5, although 4-pyridyl oxide in 6 is less basic and a better nucleofuge than 2-pyridyl oxide in 5

  2. Investigation of the influence of incomplete fusion on complete fusion of {sup 12}C-induced reactions at {approx} 4-7.2 MeV/nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Amanuel, F.K. [INFN, Laboratori Nazionali di Legnaro, Legnaro (Padova) (Italy); Zelalem, B.; Chaubey, A.K. [Addis Ababa University, Department of Physics, P.O.Box 1176, Addis Ababa (Ethiopia); Agarwal, Avinash [Bareilly College, Department of Physics, Bareilly (India); Rizvi, I.A.; Maheshwari, Anjana; Ahmed, Tauseef [Aligarh Muslim University, Department of Physics, Aligarh (India)

    2011-12-15

    In this paper, we present the results of our investigation of reaction dynamics leading to incomplete fusion of heavy ions at moderate excitation energies, especially the influence of incomplete fusion on complete fusion of {sup 12}C -induced reactions at specific energies {approx} 4-7.2M eV/nucleon. Excitation functions of various reaction products populated via complete and/or incomplete fusions of a {sup 12}C projectile with {sup 93}Nb, {sup 59}Co and {sup 52}Cr targets were measured at several specific energies {approx} 4-7.2 MeV/nucleon, using a recoil catcher technique, followed by off-line {gamma}-ray spectrometry. The measured excitation functions were compared with theoretical values obtained using the PACE4 statistical model code. For representative non-{alpha}-emitting channels in the {sup 12}C + {sup 93}Nb system, the experimentally measured excitation functions were, in general, found to be in good agreement with the theoretical predictions. However, for {alpha}-emitting channels in the {sup 12}C + {sup 93}Nb, {sup 12}C + {sup 59}Co, and {sup 12}C + {sup 52}Cr systems, the measured excitation functions were higher than the predictions of the theoretical model code, which may be credited to incomplete fusion reactions at these energies. An attempt was made to estimate the incomplete fusion fraction for the present systems, which revealed that the fraction was sensitive to the projectile energy and mass asymmetry of the entrance channel. (orig.)

  3. Backward emitted high-energy neutrons in hard reactions of p and π+ on carbon

    Science.gov (United States)

    Malki, A.; Alster, J.; Asryan, G.; Averichev, Y.; Barton, D.; Baturin, V.; Bukhtoyarova, N.; Carroll, A.; Heppelmann, S.; Kawabata, T.; Leksanov, A.; Makdisi, Y.; Minina, E.; Navon, I.; Nicholson, H.; Ogawa, A.; Panebratsev, Yu.; Piasetzky, E.; Schetkovsky, A.; Shimanskiy, S.; Tang, A.; Watson, J. W.; Yoshida, H.; Zhalov, D.

    2002-01-01

    Beams of protons and pions of 5.9 GeV/c were incident on a C target. Neutrons emitted into the backward hemisphere, in the laboratory system, were detected in (triple) coincidence with two emerging particles of tranverse momenta pt>0.6 GeV/c. We determined that for (46.5+/-3.7)% of the proton-induced events and for (40.8+/-4.5)% of the pion-induced events with the two high-pt particles, there is also at least one backward emitted neutron with momentum greater than 0.32 GeV/c. This observation is in sharp contrast to a well- established universal pattern from a large variety of earlier inclusive measurements with hadrons, electrons, photons, neutrinos, and antineutrinos where the probability for backward nucleon emission was in the 5 to 10 % range. We present also a measurement of the momentum spectra for the backward going neutrons. The spectra have the same universal shape observed in the inclusive reactions. We speculate that the enhanced backward neutron emission in this semi-inclusive region could be an indication for a strong dependence of the cross section on the squared total center-of-mass energy (s) and for the importance of short-range nucleon-nucleon correlations.

  4. Polystyrene copolymer supported by substituted (1R,2R)-1,2-diphenylethane-1,2-diamine-copper(II) complexes: a recyclable catalyst for asymmetric Henry reactions

    Czech Academy of Sciences Publication Activity Database

    Androvič, L.; Drabina, P.; Panov, I.; Frumarová, Božena; Kalendová, A.; Sedlák, M.

    2014-01-01

    Roč. 25, č. 9 (2014), s. 775-780 ISSN 0957-4166 Institutional support: RVO:61389013 Keywords : cooper complexes * copolymers * asymmetric Henry reaction Subject RIV: CC - Organic Chemistry Impact factor: 2.155, year: 2014

  5. BOREAS TGB-12 Soil Carbon and Flux Data of NSA-MSA in Raster Format

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains (1) estimates of soil carbon stocks by horizon based on soil survey data and analyses of data from individual soil profiles; (2) estimates of...

  6. Reaction of carbon tetrachloride with methane in a non-equilibrium plasma at atmospheric pressure, and characterisation of the polymer thus formed

    Energy Technology Data Exchange (ETDEWEB)

    Gaikwad, Vaibhav [Process Safety and Environment Protection Research Group, School of Engineering, The University of Newcastle, Callaghan, NSW 2308 (Australia); Kennedy, Eric, E-mail: Eric.Kennedy@newcastle.edu.au [Process Safety and Environment Protection Research Group, School of Engineering, The University of Newcastle, Callaghan, NSW 2308 (Australia); Mackie, John [Process Safety and Environment Protection Research Group, School of Engineering, The University of Newcastle, Callaghan, NSW 2308 (Australia); Holdsworth, Clovia [Centre for Organic Electronics, Chemistry Building, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308 (Australia); Molloy, Scott; Kundu, Sazal; Stockenhuber, Michael [Process Safety and Environment Protection Research Group, School of Engineering, The University of Newcastle, Callaghan, NSW 2308 (Australia); Dlugogorski, Bogdan [School of Engineering and Information Technology, Murdoch University, Murdoch, WA 6150 (Australia)

    2014-09-15

    Highlights: • CCl{sub 4} remediation using non-equilibrium plasma and non-oxidative conditions is proposed. • The reaction mechanism relies on experimental data and quantum chemical analysis. • Comprehensive mass balance for the reaction is provided. • CCl{sub 4} is converted to an environmentally benign and potentially useful polymer. • Characterisation of the polymer structure based on NMR and FTIR analyses is presented. - Abstract: In this paper we focus on the development of a methodology for treatment of carbon tetrachloride utilising a non-equilibrium plasma operating at atmospheric pressure, which is not singularly aimed at destroying carbon tetrachloride but rather at converting it to a non-hazardous, potentially valuable commodity. This method encompasses the reaction of carbon tetrachloride and methane, with argon as a carrier gas, in a quartz dielectric barrier discharge reactor. The reaction is performed under non-oxidative conditions. Possible pathways for formation of major products based on experimental results and supported by quantum chemical calculations are outlined in the paper. We elucidate important parameters such as carbon tetrachloride conversion, product distribution, mass balance and characterise the chlorinated polymer formed in the process.

  7. Characteristics of black carbon in snow from Laohugou No. 12 glacier on the northern Tibetan Plateau.

    Science.gov (United States)

    Zhang, Yulan; Kang, Shichang; Li, Chaoliu; Gao, Tanguang; Cong, Zhiyuan; Sprenger, Michael; Liu, Yajun; Li, Xiaofei; Guo, Junming; Sillanpää, Mika; Wang, Kun; Chen, Jizu; Li, Yang; Sun, Shiwei

    2017-12-31

    Black carbon (BC) emitted from the incomplete combustion of biomass and fossil fuel impacts the climate system, cryospheric change, and human health. This study documents black carbon deposition in snow from a benchmark glacier on the northern Tibetan Plateau. Significant seasonality of BC concentrations indicates different input or post-depositional processes. BC particles deposited in snow had a mass volume median diameter slightly larger than that of black carbon particles typically found in the atmosphere. Also, unlike black carbon particles in the atmosphere, the particles deposited in snow did not exhibit highly fractal morphology by Scanning Transmission Electron Microscope. Footprint analysis indicated BC deposited on the glacier in summer originated mainly from Central Asia; in winter, the depositing air masses generally originated from Central Asia and Pakistan. Anthropogenic emissions play an important role on black carbon deposition in glacial snow, especially in winter. The mass absorption efficiency of BC in snow at 632nm exhibited significantly seasonality, with higher values in summer and lower values in winter. The information on black carbon deposition in glacial snow provided in this study could be used to help mitigate the impacts of BC on glacier melting on the northern Tibetan Plateau. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. FY12 ARRA-NRAP Report – Studies to Support Risk Assessment of Geologic Carbon Sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Cantrell, Kirk J.; Shao, Hongbo; Thompson, C. J.; Zhong, Lirong; Jung, Hun Bok; Um, Wooyong

    2011-09-27

    This report summarizes results of research conducted during FY2012 to support the assessment of environmental risks associated with geologic carbon dioxide (CO2) sequestration and storage. Several research focus areas are ongoing as part of this project. This includes the quantification of the leachability of metals and organic compounds from representative CO2 storage reservoir and caprock materials, the fate of metals and organic compounds after release, and the development of a method to measure pH in situ under supercritical CO2 (scCO2) conditions. Metal leachability experiments were completed on 6 different rock samples in brine in equilibrium with scCO2 at representative geologic reservoir conditions. In general, the leaching of RCRA metals and other metals of concern was found to be limited and not likely to be a significant issue (at least, for the rocks tested). Metals leaching experiments were also completed on 1 rock sample with scCO2 containing oxygen at concentrations of 0, 1, 5, and 10% to simulate injection of CO2 originating from the oxy-fuel combustion process. Significant differences in the leaching behavior of certain metals were observed when oxygen is present in the CO2. These differences resulted from oxidation of sulfides, release of sulfate, ferric iron and other metals, and subsequent precipitation of iron oxides and some sulfates such as barite. Experiments to evaluate the potential for mobilization of organic compounds from representative reservoir materials and cap rock and their fate in porous media (quartz sand) have been conducted. Results with Fruitland coal and Gothic shale indicate that lighter organic compounds were more susceptible to mobilization by scCO2 compared to heavier compounds. Alkanes demonstrated very low extractability by scCO2. No significant differences were observed between the extractability of organic compounds by dry or water saturated scCO2. Reaction equilibrium appears to have been reached by 96 hours. When

  9. Trends of 13C/12C ratios in pinyon tree rings of the American Southwest and the global carbon cycle

    International Nuclear Information System (INIS)

    Leavitt, S.W.; Long, A.

    1986-01-01

    An accurate atmospheric 13 C/ 12 C chronology can provide important constraints to models of the global carbon cycle. Trees accumulate carbon from atmospheric CO 2 into growth rings and offer potential for 13 C/ 12 C reconstructions, but results have not been reproducible. This paper presents δ 13 C curves from 5 sites, representing 20 pinyon (Pinus edulis) trees, where cores of 4 trees from each site have been pooled into a composite sample. Isotopic analysis of cellulose in 5-yr ring groups produces curves with a general trend of decreasing δ 13 C after 1800, but with pronounced short-term fluctuations superimposed upon the trend. Evidence indicates the fluctuations are strongly related to moisture availability (drought). A mean curve of the 5 δ 13 C chronologies from which the fossil-fuel component is subtracted suggests a substantial biospheric CO 2 contribution to the atmosphere since 1800

  10. Spectroscopic and chromatographic characterisation of a pentafluorophenylpropyl silica phase end-capped in supercritical carbon dioxide as a reaction solvent.

    Science.gov (United States)

    Ashu-Arrah, Benjamin A; Glennon, Jeremy D; Albert, Klaus

    2013-07-12

    This research uses solid-state nuclear magnetic resonance (NMR) spectroscopy to characterise the nature and amount of different surface species, and chromatography to evaluate phase properties of a pentafluorophenylpropyl (PFPP) bonded silica phase prepared and end-capped using supercritical carbon dioxide (sc-CO2) as a reaction solvent. Under sc-CO2 reaction conditions (at temperature of 100 °C and pressure of 414 bar), a PFPP silica phase was prepared using 3-[(pentafluorophenyl)propyldimethylchlorosilane] within 1h. The bonded PFPP phase was subsequently end-capped with bis-N,O-trimethylsilylacetamide (BSA), hexamethyldisilazane (HMDS) and trimethylchlorosilane (TMCS) within 1h under the same sc-CO2 reaction conditions (100 °C/4141 bar). Elemental microanalysis, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were used to provide support data to solid-state NMR and chromatographic evaluation. Results revealed a surface coverage of 2.2 μmol/m(2) for the non-end-capped PFPP silica phase while the PFPP phase end-capped with BSA gave a higher surface coverage (3.9 μmol/m(2)) compared to HMDS (2.9 μmol/m(2)) and TMCS (2.8 μmol/m(2)). (29)Si CP/MAS NMR analysis of the PFPP end-capped with BSA shows a significant decrease in the amount of Q(3) (free silanols) and Q(4) (siloxane groups) species, coupled with the absence of the most reactive Q(2) (geminal silanols) in addition to increased amount of a single resonance peak centred at +13 ppm (MH) corresponding to -Si-O-*Si-CH3 bond. (13)C CP/MAS NMR shows the resonance corresponding to the propyl linkage (CH3CH2CH2-) and methyl groups (Si(CH3)n) confirming successful silanisation and endcapping reactions in sc-CO2. Chromatographic evaluation of the BSA end-capped PFPP phase with Neue text mixture revealed improved chromatographic separation as evidenced in the enhanced retention of hydrophobic markers and decreased retention for basic solutes. Moreover, chromatography revealed a change in

  11. Lignin-derived electrospun carbon nanofiber mats with supercritically deposited Ag nanoparticles for oxygen reduction reaction in alkaline fuel cells

    International Nuclear Information System (INIS)

    Lai, Chuilin; Kolla, Praveen; Zhao, Yong; Fong, Hao; Smirnova, Alevtina L.

    2014-01-01

    Highlights: • Electrospun carbon nanofiber mats were prepared from a natural product of lignin. • The freestanding mats were flexible with BET specific surface area of ∼583 m 2 /g. • The mats were surface-deposited with Ag nanoparticles via the scCO 2 method. • Novel electrocatalytic systems of Ag/ECNFs exhibited high activities towards ORR. - Abstract: Ag nanoparticles (AgNPs) (11, 15, and 25 wt.%) were deposited on the surface of the freestanding and mechanically flexible mats consisting of lignin-derived electrospun carbon nanofibers (ECNFs) by the supercritical CO 2 method followed by the thermal treated at 180 °C. The electrochemical activity of Ag/ECNFs electrocatalyst systems towards oxygen reduction reaction (ORR) was studied in 0.1 M KOH aqueous solution using the rotating disk/rotating ring disk electrode (RDE/RRDE) technique. The SEM, TEM, and XRD results indicated that, the spherical AgNPs were uniformly distributed on the ECNF surface with sizes in the range of 2-10 nm. The electrocatalytic results revealed that, all of the Ag/ECNFs systems exhibited high activity in ORR and demonstrated close-to-theoretical four-electron pathway. In particular, the mass activity of 15 wt.% Ag/ECNFs system was the highest (119 mA mg −1 ), exceeding that of HiSPEC 4100™ commercial Pt/C catalyst (98 mA mg −1 ). This study suggested that the lignin-derived ECNF mats surface-deposited with AgNPs would be promising as cost-effective and highly efficient electrocatalyst for ORR in alkaline fuel cells

  12. Electrocatalytic Performance of Carbon Supported WO3-Containing Pd–W Nanoalloys for Oxygen Reduction Reaction in Alkaline Media

    Directory of Open Access Journals (Sweden)

    Nan Cui

    2018-05-01

    Full Text Available In this paper, we report that WOx containing nanoalloys exhibit stable electrocatalytic performance in alkaline media, though bulk WO3 is easy to dissolve in NaOH solution. Carbon supported oxide-rich Pd–W alloy nanoparticles (PdW/C with different Pd:W atom ratios were prepared by the reduction–oxidation method. Among the catalysts, the oxide-rich Pd0.8W0.2/C (Pd/W = 8:2, atom ratio exhibits the highest catalytic activity for the oxygen reduction reaction. The X-ray photoelectron spectroscopy data shows that ~40% of Pd atoms and ~60% of the W atoms are in their oxide form. The Pd 3d5/2 binding energy of the oxide-rich Pd–W nanoalloys is higher than that of Pd/C, indicating the electronic structure of Pd is affected by the strong interaction between Pd and W/WO3. Compare to Pd/C, the onset potential of the oxygen reduction reaction at the oxide-rich Pd0.8W0.2/C shifts to a higher potential. The current density (mA·mg Pd−1 at the oxide-rich Pd0.8W0.2/C is ~1.6 times of that at Pd/C. The oxide-rich Pd0.8W0.2/C also exhibits higher catalytic stability than Pd/C, which demonstrates that it is a prospective candidate for the cathode of fuel cells operating with alkaline electrolyte.

  13. Novel C-2 epimerization of aldoses promoted by nickel(II) diamine complexes, involving a stereospecific pinacol-type 1,2-carbon shift

    International Nuclear Information System (INIS)

    Tanase, Tomoaki; Shimizu, Fumihiko; Kuse, Manabu; Yano, Shigenobu; Hidai, Masanobu; Yoshikawa, Sadao

    1988-01-01

    The newly discovered C-2 epimerization of aldoses promoted by nickel(II) diamine complexes has been investigated in detail by using 13 C-enriched D-glucose, 13 C NMR spectroscopy, and EXAFS (extended x-ray absorption fine structure) analysis. Aldoses treated with nickel(II) diamine complexes (diamine = N,N,N'-trimethylethylenediamine (N,N,N'-Me 3 en), N,N,N',N'-tetramethylethylenediamine (N,N,N',N'-Me 4 en), etc.) in methanolic solutions were rapidly (60 degree C, 3-5 min) epimerized at C-2 to give equilibrium mixtures where the ratio of C-2 epimers shifts to the side of the naturally rare mannose-type aldoses (having the cis arrangement of C-2 and C-3 hydroxyl groups) compared with those in the thermodynamic equilibrium states. The epimerization product of D-[1- 13 C]glucose was exclusively D-[2- 13 C]mannose, demonstrating that the reaction involves a stereospecific 1,2-shift of the carbon skeleton resulting in inversion of configuration at C-2. Furthermore, the absorption and circular dichroism spectra of the reaction solutions indicated the presence of an intermediate nickel(II) complex containing both diamine and sugar components, which was directly revealed by EXAFS analysis to be a mononuclear nickel(II) complex having octahedral coordination geometry. All these observations strongly suggest that the C-2 epimerization proceeds through an intermediate mononuclear nickel(II) complex, where the carbinolamine-like adduct of aldose with diamine in an open-chain form is epimerized at C-2 by a stereospecific rearrangement of the carbon skeleton or a pinacol-type rearrangement involving a cyclic transition state. 44 refs., 5 figs., 4 tabs

  14. 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

  15. Diels-Alder Reactions of 12-Hydroxy-9(10®20-5aH-abeo-abieta-1(10,8(9,12(13-triene-11,14-dione

    Directory of Open Access Journals (Sweden)

    Shougang Hu

    2013-06-01

    Full Text Available 12-Hydroxy-9(10®20-5aH-abeo-abieta-1(10,8(9,12(13-triene-11,14-dione (quinone 2 served as the dienophile in numerous intermolecular Diels-Alder reactions. These cycloadditions were conducted either thermally (including microwave heating or with Lewis acid activation. While most dienes reacted with quinone 2 in good chemical yield, others were incompatible under the experimental conditions used.

  16. The dominance of the ν(0d5/22 configuration in the N=8 shell in 12Be from the breakup reaction on a proton target at intermediate energy

    Directory of Open Access Journals (Sweden)

    Le Xuan Chung

    2017-11-01

    Full Text Available The momentum distribution of 11Be fragments produced by the breakup of 12Be interacting with a proton target at 700.5 MeV/u energy has been measured at GSI Darmstadt. To obtain the structure information on the anomaly of the N=8 neutron shell, the momentum distribution of 11Be fragments from the one-neutron knockout Be12(p,pn reaction, measured in inverse kinematics, has been analysed in the distorted wave impulse approximation (DWIA based on a quasi-free scattering scenario. The DWIA analysis shows a surprisingly strong contribution of the neutron 0d5/2 orbital in 12Be to the transverse momentum distribution of the 11Be fragments. The single-neutron 0d5/2 spectroscopic factor deduced from the present knock-out data is 1.39(10, which is significantly larger than that deduced recently from data of 12Be breakup on a carbon target. This result provides a strong experimental evidence for the dominance of the neutron ν(0d5/22 configuration in the ground state of 12Be.

  17. Exact finite range DWBA results for the /sup 12/C(p,d)/sup 11/C reaction at 700 MeV. [Differential cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Rost, E; Shepard, J R [Colorado Univ., Boulder (USA). Nuclear Physics Lab.

    1975-12-08

    The differential cross sections for the /sup 12/C(p,d)/sup 11/C(g.s.) reaction at 700 MeV have been calculated in a full finite range DWBA approach. The absolute cross sections agree with the data and are dominated by contributions arising from the deuteron D-state.

  18. /sup 16/O(/sup 16/O, /sup 12/C)/sup 20/Ne reaction in the framework of the coupled channel formalism

    Energy Technology Data Exchange (ETDEWEB)

    Krause, O; Scheid, W; Greiner, W [Frankfurt Univ. (Germany, F.R.). Inst. fuer Theoretische Physik

    1974-01-01

    The transfer reaction /sup 16/O(/sup 16/O, /sup 12/C)/sup 20/Ne is treated in the coupled channel formalism. The influence of the transfer channels on the intermediate structure in the elastic excitation function is discussed. The /sup 16/O and /sup 20/Ne-nuclei are described in an ..cap alpha..-cluster model.

  19. Reaction cross sections for protons on {sup 12}C, {sup 40}Ca, {sup 90}Zr and {sup 208}Pb at energies between 80 and 180 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Auce, A.; Ingemarsson, A.; Johansson, R. [and others

    2005-04-01

    Results of reaction cross section measurements on {sup 12}C, {sup 40}Ca, {sup 90}Zr and {sup 208}Pb at incident proton energies between 80 and 180 MeV and for {sup 58}Ni at 81 MeV are presented. The experimental procedure is described and the results are compared with earlier measurements and predictions using macroscopic and microscopic models.

  20. Reaction cross sections for protons on 12C, 40Ca, 90Zr and 208Pb at energies between 80 and 180 MeV

    International Nuclear Information System (INIS)

    Auce, A.; Ingemarsson, A.; Johansson, R.

    2005-04-01

    Results of reaction cross section measurements on 12 C, 40 Ca, 90 Zr and 208 Pb at incident proton energies between 80 and 180 MeV and for 58 Ni at 81 MeV are presented. The experimental procedure is described and the results are compared with earlier measurements and predictions using macroscopic and microscopic models