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Sample records for catalysed partial oxidation

  1. Axial Changes of Catalyst Structure and Temperature in a Fixed-Bed Microreactor During Noble Metal Catalysed Partial Oxidation of Methane

    DEFF Research Database (Denmark)

    Hannemann, S.; Grunwaldt, Jan-Dierk; Kimmerle, B.;

    2009-01-01

    -heating by the exothermic methane oxidation was too strong. The results indicate that in the oxidized zone mainly combustion of methane occurs, whereas in the reduced part direct partial oxidation and reforming reactions prevail. The results demonstrate how spatially resolved spectroscopy can help in understanding......-line mass spectrometry. This experimental strategy allowed collecting data on the structure of the noble metal (oxidation state) and the temperature along the catalyst bed. The reaction was investigated in a fixed-bed quartz microreactor (1-1.5 mm diameter) following the catalytic performance by on-line gas...... catalytic reactions involving different reaction zones and gradients even in micro scale fixed-bed reactors....

  2. Evaluating Pt-Ru/C mixtures as ethanol electro-oxidation catalysers

    OpenAIRE

    Bibian Alonso Hoyos; Javier González; Carlos Sánchez

    2010-01-01

    This work studies ethanol electro-catalytic oxidation by cyclic voltametry in sulphuric acid solutions at different temperatures and concetrations, using platinum.rutenium mixtures supported in vitreous carbon as catalysers. The results indicate that ethanol oxidation in theses electrodes is irreversible, has slow kinetics, is controlled by charge transfer and is brought about by a bi-functional reaction mechanism, this being ethanol adsorption on platinum atoms and additional oxidation of sp...

  3. Selenium dioxide catalysed oxidation of acetic acid hydrazide by bromate in aqueous hydrochloric acid medium

    Indian Academy of Sciences (India)

    R S Yalgudre; G S Gokavi

    2012-07-01

    Selenium dioxide catalysed acetic acid hydrazide oxidation by bromate was studied in hydrochloric acid medium. The order in oxidant concentration, substrate and catalyst were found to be unity. Increasing hydrogen ion concentration increases the rate of the reaction due to protonation equilibria of the oxidant. The mechanism of the reaction involves prior complex formation between the catalyst and substrate, hydrazide, followed by its oxidation by diprotonated bromate in a slow step. Acetic acid was found to be the oxidation product. Other kinetic data like effect of solvent polarity and ionic strength on the reaction support the proposed mechanism.

  4. Evaluating Pt-Ru/C mixtures as ethanol electro-oxidation catalysers

    Directory of Open Access Journals (Sweden)

    Bibian Alonso Hoyos

    2010-04-01

    Full Text Available This work studies ethanol electro-catalytic oxidation by cyclic voltametry in sulphuric acid solutions at different temperatures and concetrations, using platinum.rutenium mixtures supported in vitreous carbon as catalysers. The results indicate that ethanol oxidation in theses electrodes is irreversible, has slow kinetics, is controlled by charge transfer and is brought about by a bi-functional reaction mechanism, this being ethanol adsorption on platinum atoms and additional oxidation of specties adsorbed in the presence of platinum and retenium oxides. Experimental results show increased catalytic activity with electrodes, followed by reduced activity for electrodes having a greater quantity of rutenium.

  5. Influence of Fe(2+)-catalysed iron oxide recrystallization on metal cycling.

    Science.gov (United States)

    Latta, Drew E; Gorski, Christopher A; Scherer, Michelle M

    2012-12-01

    Recent work has indicated that iron (oxyhydr-)oxides are capable of structurally incorporating and releasing metals and nutrients as a result of Fe2+-induced iron oxide recrystallization. In the present paper, we briefly review the current literature examining the mechanisms by which iron oxides recrystallize and summarize how recrystallization affects metal incorporation and release. We also provide new experimental evidence for the Fe2+-induced release of structural manganese from manganese-doped goethite. Currently, the exact mechanism(s) for Fe2+-induced recrystallization remain elusive, although they are likely to be both oxide-and metal-dependent. We conclude by discussing some future research directions for Fe2+-catalysed iron oxide recrystallization.

  6. Atomic scale observation of oxygen delivery during silver-oxygen nanoparticle catalysed oxidation of carbon nanotubes

    Science.gov (United States)

    Yue, Yonghai; Yuchi, Datong; Guan, Pengfei; Xu, Jia; Guo, Lin; Liu, Jingyue

    2016-07-01

    To probe the nature of metal-catalysed processes and to design better metal-based catalysts, atomic scale understanding of catalytic processes is highly desirable. Here we use aberration-corrected environmental transmission electron microscopy to investigate the atomic scale processes of silver-based nanoparticles, which catalyse the oxidation of multi-wall carbon nanotubes. A direct semi-quantitative estimate of the oxidized carbon atoms by silver-based nanoparticles is achieved. A mechanism similar to the Mars-van Krevelen process is invoked to explain the catalytic oxidation process. Theoretical calculations, together with the experimental data, suggest that the oxygen molecules dissociate on the surface of silver nanoparticles and diffuse through the silver nanoparticles to reach the silver/carbon interfaces and subsequently oxidize the carbon. The lattice distortion caused by oxygen concentration gradient within the silver nanoparticles provides the direct evidence for oxygen diffusion. Such direct observation of atomic scale dynamics provides an important general methodology for investigations of catalytic processes.

  7. Kinetics and selectivity of the copper-catalysed oxidative coupling of 4-(2 ',6 '-dimethylphenoxyl-2,6-dimethylphenol

    NARCIS (Netherlands)

    Baesjou, PJ; Driessen, WL; Challa, G; Reedijk, J

    1999-01-01

    The kinetics of the copper/N-methylimidazole catalysed oxidative coupling reaction with the C-O coupled dimer of 2,6-dimethylphenol (DMP or monomer), viz. 4-(2',6'-dimethylphenoxy)-2,6-dimethylphenol (dimer), as the substrate have been studied. The reaction was found to obey Michaelis-Menten kinetic

  8. The electrochemical oxidation of toluene catalysed by Co(II) in N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide.

    Science.gov (United States)

    Balaji, S; Kannan, K; Moon, I S

    2015-12-14

    The electrochemical oxidation of toluene in N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([bmpyr](+)[Ntf2](-)) was investigated by using cyclic voltammetry and galvanostatic electrolysis in the presence of Co(II) at a Pt disc working electrode. Cyclic voltammetry (CV) investigations revealed that Co(II)-Co(III) oxidation is a diffusion controlled electron transfer process. The diffusion coefficient values of Co(II) were found to increase from 0.38 × 10(-7) to 1.9 × 10(-7) cm(2) s(-1) as the temperature was increased from 25 °C to 80 °C. The CV peak current for toluene electro-oxidation increased by nearly 7 fold in the presence of Co(II) demonstrating a good catalytic effect. Co(II) catalysed galvanostatic electrolysis of toluene at room temperature has shown that benzaldehyde was formed along with a small quantity of 3-methyl-1-hexanol. PMID:26538114

  9. Characterisation and oxidation stability of monoacylglycerols from partially hydrogenated corn oil.

    Science.gov (United States)

    Zhang, Zhen; Wang, Yong; Ma, Xiang; Wang, Erpei; Liu, Manman; Yan, Rian

    2015-04-15

    This study reported the characterisation of some types of monoacylglycerols (MAGs) obtained by the glycerolysis of different partially hydrogenated corn oils (PHCOs) catalysed by Al2O3 loaded with K2CO3 (K2CO3/Al2O3) under the previous selected conditions. A two-stage molecular distillation method of purifying the MAGs was introduced, and the obtained MAG products were more than 90.0 wt.% pure. The fatty acid composition of corn oil significantly changed after hydrogenation sequentially catalysed by Pricat™ Ni catalysts (9908 Ni/kieselguhr and 9920 Ni/Al2O3). The PHCO samples generated typical structures with β'-form crystals. Moreover, the melting regions of all hydrogenated samples and their MAGs shifted to higher temperatures. The oxidation stability of MAGs has been significantly increased using hydrogenation to change the fatty acid composition. PMID:25465996

  10. Partial oxidation of 2-propanol on perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Sumathi, R.; Viswanathan, B.; Varadarajan, T.K. [Indian Inst. of Tech., Madras (India). Dept. of Chemistry

    1998-12-31

    Partial oxidation of 2-propanol was carried out on AB{sub 1-x}B`{sub x}O{sub 3} (A=Ba, B=Pb, Ce, Ti; B`=Bi, Sb and Cu) type perovskite oxides. Acetone was the major product observed on all the catalysts. All the catalysts underwent partial reduction during the reaction depending on the composition of the reactant, nature of the B site cation and the extent of substitution at B site. The catalytic activity has been correlated with the reducibility of the perovskite oxides determined from Temperature Programmed Reduction (TPR) studies. (orig.)

  11. Heterogeneous partial oxidation catalysis on metal oxides

    OpenAIRE

    Védrine, Jacques C.; Fechete, Ioana

    2016-01-01

    International audience This review paper presents an overview of heterogeneous selective ammoxidation and oxidative dehydrogenation (ODH) of light alkanes, particularly of ethane. The conversion of ethane to ethene is in great demand in the domestic and worldwide chemical industry. The review has been voluntarily restricted to metal oxide-type catalysts, as it is devoted to the special issue honouring Edmond Payen and is based on 30 years of experience and discussions with pioneering scien...

  12. Modelling of the partial oxidation of {alpha}, {beta}-unsaturated aldehydes on Mo-V-oxides based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Boehnke, H.; Petzoldt, J.C.; Stein, B.; Weimer, C.; Gaube, J.W. [Technische Univ. Darmstadt (Germany). Inst. fuer Chemische Technologie

    1998-12-31

    A kinetic model based on the Mars-van Krevelen mechanism that allows to describe the microkinetics of the heterogeneously catalysed partial oxidation of {alpha}, {beta}-unsaturated aldehydes is presented. This conversion is represented by a network, composed of the oxidation of the {alpha}, {beta}-unsaturated aldehyde towards the {alpha}, {beta}-unsaturated carboxylic acid and the consecutive oxidation of the acid as well as the parallel reaction of the aldehyde to products of deeper oxidation. The reaction steps of aldehyde respectively acid oxidation and catalyst reoxidation have been investigated separately in transient experiments. The combination of steady state and transient experiments has led to an improved understanding of the interaction of the catalyst with the aldehyde and the carboxylic acids as well as to a support of the kinetic model assumptions. (orig.)

  13. Mechanistic study of ruthenium (III) catalysed oxidation of L-lysine by diperiodatoargentate (III) in aqueous alkaline medium

    Indian Academy of Sciences (India)

    R R Hosamani; S T Nandibewoor

    2009-05-01

    The kinetics of Ru(III) catalysed oxidation of L-lysine by diperiodatoargentate (III) (DPA) in alkaline medium at 298 K and a constant ionic strength of 0.50 mol dm-3 was studied spectrophotometrically. The oxidation products are aldehyde (5-aminopentanal) and Ag (I). The stoichiometry is i.e. [L-lysine] : [DPA] = 1 : 1. The reaction is of first order in [Ru(III)] and [DPA] and is less than unit order in both [L-lys] and [alkali]. Addition of periodate had a retarding effect on the reaction. The oxidation reaction in alkaline medium has been shown to proceed via a Ru(III)-L-lysine complex, which further reacts with one molecule of monoperiodatoargentate(III) (MPA) in a rate determining step followed by other fast steps to give the products. The main products were identified by spot test, IR, GC-MS studies. The activation parameters with respect to slow step of the mechanism are computed and discussed and thermodynamic quantities are also determined. The active species of catalyst and oxidant have been identified.

  14. Implementation of steady state approximation for modelling of reaction kinetic of UV catalysed hydrogen peroxide oxidation of starch

    Science.gov (United States)

    Kumoro, Andri Cahyo; Retnowati, Diah Susetyo; Ratnawati, Budiyati, Catarina Sri

    2015-12-01

    With regard to its low viscosity, high stability, clarity, film forming and binding properties, oxidised starch has been widely used in various applications specifically in the food, paper, textile, laundry finishing and binding materials industries. A number of methods have been used to produce oxidised starch through reactions with various oxidizing agents, such as hydrogen peroxide, air oxygen, ozone, bromine, chromic acid, permanganate, nitrogen dioxide and hypochlorite. Unfortunately, most of previous works reported in the literatures were focused on the study of reaction mechanism and physicochemical properties characterization of the oxidised starches produced without investigation of the reaction kinetics of the oxidation process. This work aimed to develop a simple kinetic model for UV catalysed hydrogen peroxide oxidation of starch through implementation of steady state approximation for the radical reaction rates. The model was then verified using experimental data available in the literature. The model verification revealed that the proposed model shows its good agreement with the experimental data as indicated by an average absolute relative error of only 2.45%. The model also confirmed that carboxyl groups are oxidised further by hydroxyl radical. The carbonyl production rate was found to follow first order reaction with respect to carbonyl concentration. Similarly, carboxyl production rate also followed first order reaction with respect to carbonyl concentration. The apparent reaction rate constant for carbonyl formation and oxidation were 6.24 × 104 s-1 and 1.01 × 104 M-1.s-1, respectively. While apparent reaction rate constant for carboxyl oxidation was 4.86 × 104 M-1.s-1.

  15. Asymmetric aerobic oxidative NHC-catalysed synthesis of dihydropyranones utilising a system of electron transfer mediators.

    Science.gov (United States)

    Axelsson, A; Hammarvid, E; Ta, L; Sundén, H

    2016-10-01

    In the context of green chemistry, the replacement of high molecular weight stoichiometric oxidants with O2 is most desirable but difficult. Here, we report the asymmetric aerobic oxidative synthesis of dihydropyranones. The oxidation is aided by a system of electron transfer mediators and is selective toward the homoenolate. The dihydropyranones can be isolated in high to excellent yields, with high ee (up to 95%). PMID:27604573

  16. Transition metal catalysed Grignard-like allylic activation across tetragonal tin(II) oxide

    Indian Academy of Sciences (India)

    Pradipta Sinha; Moloy Banerjee; Abhijit Kundu; Sujit Roy

    2002-08-01

    The reaction of allyl halide and a carbonyl compound under the aegis of tetragonal tin(II) oxide and catalytic 8, 10 metal complexes provides the corresponding homoallylic alcohol, via a novel allyl tin intermediate.

  17. Oxidation and β-Alkylation of Alcohols Catalysed by Iridium(I) Complexes with Functionalised N-Heterocyclic Carbene Ligands.

    Science.gov (United States)

    Jiménez, M Victoria; Fernández-Tornos, Javier; Modrego, F Javier; Pérez-Torrente, Jesús J; Oro, Luis A

    2015-12-01

    The borrowing hydrogen methodology allows for the use of alcohols as alkylating agents for CC bond forming processes offering significant environmental benefits over traditional approaches. Iridium(I)-cyclooctadiene complexes having a NHC ligand with a O- or N-functionalised wingtip efficiently catalysed the oxidation and β-alkylation of secondary alcohols with primary alcohols in the presence of a base. The cationic complex [Ir(NCCH3 )(cod)(MeIm(2- methoxybenzyl))][BF4 ] (cod=1,5-cyclooctadiene, MeIm=1-methylimidazolyl) having a rigid O-functionalised wingtip, shows the best catalyst performance in the dehydrogenation of benzyl alcohol in acetone, with an initial turnover frequency (TOF0 ) of 1283 h(-1) , and also in the β-alkylation of 2-propanol with butan-1-ol, which gives a conversion of 94 % in 10 h with a selectivity of 99 % for heptan-2-ol. We have investigated the full reaction mechanism including the dehydrogenation, the cross-aldol condensation and the hydrogenation step by DFT calculations. Interestingly, these studies revealed the participation of the iridium catalyst in the key step leading to the formation of the new CC bond that involves the reaction of an O-bound enolate generated in the basic medium with the electrophilic aldehyde. PMID:26493780

  18. Experimental and theoretical insights into the oxodiperoxomolybdenum-catalysed sulphide oxidation using hydrogen peroxide in ionic liquids.

    Science.gov (United States)

    Carrasco, Carlos J; Montilla, Francisco; Alvarez, Eleuterio; Mealli, Carlo; Manca, Gabriele; Galindo, Agustín

    2014-09-28

    The oxidation of organic sulphides with aqueous hydrogen peroxide in ionic liquids (ILs) catalysed by oxodiperoxomolybdenum complexes was investigated. The selective formation of several sulfones was achieved using the 1 : 3 ratio of sulphide : H2O2 in [C4mim][PF6] (C4mim = 1-butyl-3-methylimidazolium) in a reaction catalysed by the [Mo(O)(O2)2(H2O)n] complex. Conversely, sulfoxides were produced with good selectivities using a 1 : 1 ratio in the same solvent in a 1 h reaction with [Mo(O)(O2)2(Mepz)2] (Mepz = methylpyrazol). The use of [C4mim][PF6] as the solvent was advantageous for two reasons: (i) the improved performance of the H2O2-IL combination; (ii) recycling of the catalyst/IL mixture without a significant diminution of conversion or selectivity. A DFT analysis using the [Mo(O)(O2)2(L)] catalysts (L = Mepz, a; 3,5-dimethylpyrazole, dmpz, b; and H2O, c) indicated that a Sharpless-type outer-sphere mechanism is more probable than a Thiel-type one. The highest barrier of the catalytic profile was the oxo-transfer step, in which the nucleophilic attack of sulphide onto the peroxide ligand occurred with formation of dioxoperoxo species. In order to yield the sulfoxide and the starting catalyst, the oxidation of the resulting dioxoperoxo species with H2O2 was found to be the most favourable pathway. Subsequently, the sulfoxide to sulfone oxidation was performed through a similar mechanism involving the [Mo(O)(O2)2(L)] catalyst. The comparable energies found for the successive two oxo-transfer steps were in agreement with the experimental formation of sulfone in both the reaction with an excess of the oxidant and the stoichiometric reaction in the absence of the oxidant. In the latter case, diphenylsulfone was isolated as the major product in the 1 : 1 combination of diphenylsulphide and [Mo(O)(O2)2(Mepz)2] in the ionic liquid [C4mim][PF6]. Also, the compounds [HMepz]4[Mo8O26(Mepz)2]·2H2O, 1, [Hdmpz]4[Mo8O26(dmpz)2]·2dmpz, , and [Hpz]4[Mo8O22(O2

  19. Low-temperature carbon monoxide oxidation catalysed by regenerable atomically dispersed palladium on alumina

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, Eric J. [Univ. of New Mexico, Albuquerque, NM (United States); DelaRiva, Andrew T. [Univ. of New Mexico, Albuquerque, NM (United States); Lin, Sen [Univ. of New Mexico, Albuquerque, NM (United States); Johnson, Ryan S. [Univ. of New Mexico, Albuquerque, NM (United States); Guo, Hua [Univ. of New Mexico, Albuquerque, NM (United States); Miller, Jeffrey T. [Argonne National Lab. (ANL), Argonne, IL (United States); Kwak, Ja Hun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); UNIST, Ulsan (Korea); Peden, Charles H.F. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kiefer, Boris [New Mexico State Univ., Las Cruces, NM (United States); Allard, Lawrence F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ribeiro, Fabio H. [Purdue Univ., West Lafayette, IN (United States); Datye, Abhaya K. [Univ. of New Mexico, Albuquerque, NM (United States)

    2014-09-15

    Catalysis by single isolated atoms of precious metals has attracted much recent interest since it promises the ultimate economy in atom efficiency. Previous reports have been confined to reducible oxide supports such as FeOx, TiO₂ or CeO₂. Here we show that isolated Pd atoms can be stabilized on industrially relevant gamma-alumina supports. At low Pd loadings (≤0.5 wt%) these catalysts contain exclusively atomically dispersed Pd species. The addition of lanthanum-oxide to the alumina, long known for its ability to improve alumina stability, is found to also help in the stabilization of isolated Pd atoms. Aberration-corrected scanning transmission electron microscopy (AC-STEM) confirms the presence of intermingled Pd and La on the gamma-alumina surface. Operando X-ray absorption spectroscopy, performed on Pd/La-alumina and Pd/gamma-alumina (0.5 wt% Pd) demonstrates the presence of catalytically active atomically dispersed ionic Pd in the Pd/La-doped gamma-alumina system. CO oxidation reactivity measurements show onset of catalytic activity at 40 °C, indicating that the ionic Pd species are not poisoned by CO. The reaction order in CO and O₂ is positive, suggesting a reaction mechanism that is different from that on metallic Pd. The catalyst activity is lost if the Pd species are reduced to their metallic form, but the activity can be regenerated by oxidation at 700 °C in air. The high-temperature stability of these ionic Pd species on commercial alumina supports makes this catalyst system of potential interest for low-temperature exhaust treatment catalysts.

  20. Selective oxidation of primary substituted aromatic amines to azoxy products using lacunary catalyses

    Institute of Scientific and Technical Information of China (English)

    A.Nezhadali; M.Akbarpour

    2010-01-01

    Some of the substituted anilines were selectively converted in to the corresponding azoxy and azobenzenes by oxidation with 30%aqueous hydrogen peroxide.The reactions were catalyzed by various heteropolyoxometalates,at boiling point of the used solvents.An improvement in the product yield and selectivity towards azoxybenzens was also observed.Azobenzenes was obtained as by-product.In the all similar cases,the highest yield of azoxy compounds was observed using K_5PW_(11) ZnO_(39) as catalyst in N,N-dimet...

  1. Catalytic partial oxidation of pyrolysis oils

    Science.gov (United States)

    Rennard, David Carl

    2009-12-01

    This thesis explores the catalytic partial oxidation (CPO) of pyrolysis oils to syngas and chemicals. First, an exploration of model compounds and their chemistries under CPO conditions is considered. Then CPO experiments of raw pyrolysis oils are detailed. Finally, plans for future development in this field are discussed. In Chapter 2, organic acids such as propionic acid and lactic acid are oxidized to syngas over Pt catalysts. Equilibrium production of syngas can be achieved over Rh-Ce catalysts; alternatively mechanistic evidence is derived using Pt catalysts in a fuel rich mixture. These experiments show that organic acids, present in pyrolysis oils up to 25%, can undergo CPO to syngas or for the production of chemicals. As the fossil fuels industry also provides organic chemicals such as monomers for plastics, the possibility of deriving such species from pyrolysis oils allows for a greater application of the CPO of biomass. However, chemical production is highly dependent on the originating molecular species. As bio oil comprises up to 400 chemicals, it is essential to understand how difficult it would be to develop a pure product stream. Chapter 3 continues the experimentation from Chapter 2, exploring the CPO of another organic functionality: the ester group. These experiments demonstrate that equilibrium syngas production is possible for esters as well as acids in autothermal operation with contact times as low as tau = 10 ms over Rh-based catalysts. Conversion for these experiments and those with organic acids is >98%, demonstrating the high reactivity of oxygenated compounds on noble metal catalysts. Under CPO conditions, esters decompose in a predictable manner: over Pt and with high fuel to oxygen, non-equilibrium products show a similarity to those from related acids. A mechanism is proposed in which ethyl esters thermally decompose to ethylene and an acid, which decarbonylates homogeneously, driven by heat produced at the catalyst surface. Chapter 4

  2. One-pot three-component synthesis of quinazolines via a copper-catalysed oxidative amination reaction.

    Science.gov (United States)

    Duan, Tiantian; Zhai, Tianran; Liu, Huanhuan; Yan, Zilong; Zhao, Yue; Feng, Lei; Ma, Chen

    2016-07-01

    A copper-catalysed three-component reaction for constructing a series of quinazoline derivatives has been developed. In this system, solvents act as the reactants and different functional groups are well tolerated to obtain corresponding products in moderate to good yields. PMID:27304252

  3. Electrochemical and partial oxidation of methane

    Science.gov (United States)

    Singh, Rahul

    2008-10-01

    negligible coke formation on the novel fabricated anode by electroless plating process. Hydrogen is an environmentally cleaner source of energy. The recent increase in the demand of hydrogen as fuel for all types of fuel cells and petroleum refining process has boosted the need of production of hydrogen. Methane, a major component of natural gas is the major feedstock for production of hydrogen. The route of partial oxidation of methane to produce syngas (CO + H2) offers significant advantages over commercialized steam reforming process for higher efficiency and lower energy requirements. Partial oxidation of methane was studied by pulsing O2 into a CH4 flow over Rh/Al2O3 in a sequence of in situ infrared (IR) cell and fixed bed reactor at 773 K. The results obtained from the sequence of an IR cell followed by a fixed bed reactor show that (i) adsorbed CO produced possesses a long residence time, indicating that adsorbed oxygen leading to the formation of CO is significantly different from those leading to CO2 and (ii) CO2 is not an intermediate species for the formation of CO. In situ IR of pulse reaction coupled with alternating reactor sequence is an effective approach to study the primary and secondary reactions as well as the nature of their adsorbed species. As reported earlier, hydrogen remains to be the most effective fuel for fuel cells, the production of high purity hydrogen from naturally available resources such as coal, petroleum, and natural gas requires a number of energy-intensive steps, making fuel cell processes for stationary electric power generation prohibitively uneconomic. Direct use of coal or coal gas as the feed is a promising approach for low cost electricity generation. Coal gas solid oxide fuel cell was studied by pyrolyzing Ohio #5 coal to coal gas and transporting to a Cu anode solid oxide fuel cell to generate power. The study of coal-gas solid oxide fuel cell is divided into two sections, i.e., (i) understanding the composition of coal gas by

  4. Partial Oxidized Arsenene: Emerging Tunable Direct Bandgap Semiconductor

    Science.gov (United States)

    Wang, Yu-Jiao; Zhou, Kai-Ge; Yu, Geliang; Zhong, Xing; Zhang, Hao-Li

    2016-01-01

    Arsenene, as a member of the Group V elemental two-dimensional materials appears on the horizon, has shown great prospects. However, its indirect bandgap limits the applications in optoelectronics. In this theoretical work, we reported that partial oxidation can tune the indirect bandgap of arsenene into the direct one. Attributed to the enthalpy decreasing linear to the oxygen ratio, partial oxidized arsenene can be controllably produced by the progressive oxidation under low temperature. Importantly, by increasing the oxygen content from 1O/18As to 18O/18As, the oxidation can narrow the direct bandgap of oxidized arsenene from 1.29 to 0.02 eV. The bandgap of partial oxidized arsenene is proportional to the oxygen content. Consequently, the partial oxidized arsenene with tunable direct bandgap has great potentials in the high efficient infra light emitter and photo-voltaic devices. PMID:27114052

  5. Partial Oxidized Arsenene: Emerging Tunable Direct Bandgap Semiconductor

    Science.gov (United States)

    Wang, Yu-Jiao; Zhou, Kai-Ge; Yu, Geliang; Zhong, Xing; Zhang, Hao-Li

    2016-04-01

    Arsenene, as a member of the Group V elemental two-dimensional materials appears on the horizon, has shown great prospects. However, its indirect bandgap limits the applications in optoelectronics. In this theoretical work, we reported that partial oxidation can tune the indirect bandgap of arsenene into the direct one. Attributed to the enthalpy decreasing linear to the oxygen ratio, partial oxidized arsenene can be controllably produced by the progressive oxidation under low temperature. Importantly, by increasing the oxygen content from 1O/18As to 18O/18As, the oxidation can narrow the direct bandgap of oxidized arsenene from 1.29 to 0.02 eV. The bandgap of partial oxidized arsenene is proportional to the oxygen content. Consequently, the partial oxidized arsenene with tunable direct bandgap has great potentials in the high efficient infra light emitter and photo-voltaic devices.

  6. Recent Progress in Direct Partial Oxidation of Methane to Methanol

    Institute of Scientific and Technical Information of China (English)

    Qijian Zhang; Dehua He; Qiming Zhu

    2003-01-01

    The direct conversion of methane to methanol has attracted a great deal of attention for nearly a century since it was first found possible in 1902, and it is still a challenging task. This review article describes recent advancements in the direct partial oxidation of methane to methanol. The history of direct oxidation of methane and the difficulties encountered in the partial oxidation of methane to methanol are briefly summarized. Recently reported developments in gas-phase homogeneous oxidation, heterogeneous catalytic oxidation and liquid phase homogeneous catalytic oxidation of methane are reviewed.

  7. CeO2 catalysed soot oxidation. The role of active oxygen to accelerate the oxidation conversion

    International Nuclear Information System (INIS)

    The influence of CeO2 in the acceleration of NOx-assisted soot oxidation has been studied in flow-reactor equipment by comparing two catalyst configurations, namely: (1) Pt upstream of soot and (2) Pt upstream of CeO2-soot. The role of CeO2 has been elucidated by means of DRIFT spectroscopy coupled with mass spectrometry and TAP reactor experiments. It was found that CeO2 has the potential to accelerate the oxidation rate of soot due to its active oxygen storage. The formation of active oxygen is initiated by NO2 in the gas phase. A synergetic effect is observed as a result of surface nitrate decomposition, which results in gas phase NO2 and desorption of active oxygen. Stored oxygen is postulated to exist in the form of surface peroxide or super oxide. Active oxygen is likely to play a role on the acceleration of soot oxidation and to contribute more than desorbed NO2 or NO2 from surface nitrate decomposition

  8. The energy-conserving nitric-oxide-reductase system in Paracoccus denitrificans. Distinction from the nitrite reductase that catalyses synthesis of nitric oxide and evidence from trapping experiments for nitric oxide as a free intermediate during denitrification.

    Science.gov (United States)

    Carr, G J; Page, M D; Ferguson, S J

    1989-02-15

    1. A Clark-type electrode that responds to nitric oxide has been used to show that cytoplasmic membrane vesicles of Paracoccus denitrificans have a nitric-oxide reductase activity. Nitrous oxide is the reaction product. NADH, succinate or isoascorbate plus 2,3,5,6-tetramethyl-1,4-phenylene diamine can act as reductants. The NADH-dependent activity is resistant to freezing of the vesicles and thus the NADH:nitric-oxide oxidoreductase activity of stored frozen vesicles provides a method for calibrating the electrode by titration of dissolved nitric oxide with NADH. The periplasmic nitrite reductase and nitrous-oxide reductase enzymes are absent from the vesicles which indicates that nitric-oxide reductase is a discrete enzyme associated with the denitrification process. This conclusion was supported by the finding that nitric-oxide reductase activity was absent from both membranes prepared from aerobically grown P. denitrificans and bovine heart submitochondrial particles. 2. The NADH: nitric-oxide oxidoreductase activity was inhibited by concentrations of antimycin or myxothiazol that were just sufficient to inhibit the cytochrome bc1 complex of the ubiquinol--cytochrome-c oxidoreductase. The activity was deduced to be proton translocating by the observations of: (a) up to 3.5-fold stimulation upon addition of an uncoupler; and (b) ATP synthesis with a P:2e ratio of 0.75. 3. Nitrite reductase of cytochrome cd1 type was highly purified from P. denitrificans in a new, high-yield, rapid two- or three-step procedure. This enzyme catalysed stoichiometric synthesis of nitric oxide. This observation, taken together with the finding that the maximum rate of NADH:nitric-oxide oxidoreductase activity catalysed by the vesicles was comparable with that of NADH:nitrate-oxidoreductase, is consistent with a role for nitric-oxide reductase in the physiological conversion of nitrate or nitrite to dinitrogen gas. 4. Intact cells of P. denitrificans also reduced nitric oxide in an

  9. The quest for new mild and selective modifications of natural structures: laccase-catalysed oxidation of ergot alkaloids leads to unexpected stereoselective C-4 hydroxylation.

    Science.gov (United States)

    Chirivì, Cosimo; Fontana, Gabriele; Monti, Daniela; Ottolina, Gianluca; Riva, Sergio; Danieli, Bruno

    2012-08-13

    Laccase-catalysed oxidation of ergot alkaloids in the absence of chemical mediators allowed the unexpected isolation of the mono-hydroxylated derivatives of compounds 2-7. Structure determination by NMR techniques clearly indicated that hydroxylation took place at the C-4 benzylic position. Quite notably, the proposed protocol allowed, for the first time, functionalisation at the C-4 position of the ergoline skeleton. Depending on the absence or on the presence of a C-10 α-methoxy substituent, hydroxylation was either stereoselective (furnishing C-4α OH derivatives) or gave rise to a C-4α/C-4β OH mixture in a 2:1 ratio, respectively. PMID:22777708

  10. Catalytic partial oxidation of methane to synthesis gas over ZRO2-based defective oxides

    NARCIS (Netherlands)

    Zhu, Jianjun

    2005-01-01

    the work presented in this thesis provides both fundamental scientific knowledge as well as a new technical dual-bed concept for synthesis gas production via catalytic partial oxidation of methane over defective ZrO2-based oxides.

  11. Partial Oxidation of Methane Over the Perovskite Oxides

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Ba0.sSr0.5Co0.8Fe0.2O3-δ and Ba0.5Sr0.5Co0.8Ti0.2O3-δ oxides were synthesized by a combined EDTA-citrate complexing method. The catalytic behavior of these two oxides with the perovskite structure was studied during the reaction of methane oxidation. The pre-treatment with methane has different effect on the catalytic activities of both the oxides. The methane pre-treatment has not resulted in the change of the catalytic activity of BSCFO owing to its excellent reversibility of the perovskite structure resulting from the excellent synergistic interaction between Co and Fe in the oxide. However, the substitution with Ti on Fe-site in the lattice makes the methane pre-treatment have an obvious influence on the activity of the formed BSCTO oxide.

  12. Catalytic Partial Oxidation of Biomass/Oil Mixture

    OpenAIRE

    Veselý, V; Hanika, J. (Jiří); Tukač, V.; LEDERER, J.; Kovač, D.

    2013-01-01

    Investigation was focussed to application of waste POX (partial oxidation), e.g., meal rape in form of suspension in high boiling hydrocarbons from crude oil distillation. There is an opportunity for utilization of biomass waste resulted from fuels bio-components production. A decrease of oxygen and water steam demand in feed for POX process was observed in this variant. Catalytic effect of iron nanoparticles or nickel nitrate as catalysts in improvement of the pilot plant biomass/oil partial...

  13. Partial oxidation of methane to syngas in tubular oxygenpermeable reactor

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A dense Ba0.5Sr0.5Co0.8Fe0.2O3-δ membrane tube was prepared by the extruding method. Furthermore, a membrane reactor with this tubular membrane was successfully applied to partial oxidation of methane (POM) reaction,in which the separation of oxygen from air and the partial oxidation of methane are integrated in one process. At 875℃,94% of methane conversion, 98% of CO selectivity, 95% of H2 selectivity, and as high as 8.8 mL/(min @cm2) of oxygen flux were obtained. In POM reaction condition, the membrane tube shows a very good stability.

  14. Advances in the Partial Oxidation of Methane to Synthesis Gas

    Institute of Scientific and Technical Information of China (English)

    Quanli Zhu; Xutao Zhao; Youquan Deng

    2004-01-01

    The conversion and utilization of natural gas is of significant meaning to the national economy,even to the everyday life of people. However, it has not become a popular industrial process as expected due to the technical obstacles. In the past decades, much investigation into the conversion of methane,predominant component of natural gas, has been carried out. Among the possible routes of methane conversion, the partial oxidation of methane to synthesis gas is considered as an effective and economically feasible one. In this article, a brief review of recent studies on the mechanism of the partial oxidation of methane to synthesis gas together with catalyst development is wherein presented.

  15. Remarkable effect of Pt nanoparticles on visible light-induced oxygen generation from water catalysed by perovskite oxides.

    Science.gov (United States)

    Gupta, Uttam; Naidu, B S; Rao, C N R

    2015-01-14

    Oxidation of water is a challenging process with a positive free energy change and it is purposeful to find good catalysts to facilitate the process. While the perovskite oxides, LaCoO3 and LaMnO3, are good electron transfer catalysts in artificial photosynthesis to produce oxygen by the oxidation of water, the electron transfer is further favoured by the presence of platinum nanoparticles, causing a substantial increase in oxygen evolution.

  16. Insights into the mechanism of oxidation of dihydroorotate to orotate catalysed by human class 2 dihydroorotate dehydrogenase: a QM/MM free energy study.

    Science.gov (United States)

    Alves, Cláudio Nahum; Silva, José Rogério A; Roitberg, Adrian E

    2015-07-21

    The dihydroorotate dehydrogenase (DHOD) enzyme catalyzes the unique redox reaction in the de novo pyrimidine biosynthesis pathway. In this reaction, the oxidation of dihydroorotate (DHO) to orotate (OA) and reduction of the flavin mononucleotide (FMN) cofactor is catalysed by DHOD. The class 2 DHOD, to which the human enzyme belongs, was experimentally shown to follow a stepwise mechanism but the data did not allow the determination of the order of bond-breaking in a stepwise oxidation of DHO. The goal of this study is to understand the reaction mechanism at the molecular level of class 2 DHOD, which may aid in the design of inhibitors that selectively impact the activity of only certain members of the enzyme family. In this paper, the catalytic mechanism of oxidation of DHO to OA in human DHOD was studied using a hybrid Quantum Mechanical/Molecular Mechanical (QM/MM) approach and Molecular Dynamics (MD) simulations. The free energy barriers calculated reveal that the mechanism in human DHOD occurs via a stepwise reaction pathway. In the first step, a proton is abstracted from the C5 of DHO to the deprotonated Ser215 side chain. Whereas, in the second step, the transfer of the hydride or hydride equivalent from the C6 of DHO to the N5 of FMN, where free energy barrier calculated by the DFT/MM level is 10.84 kcal mol(-1). Finally, a residual decomposition analysis was carried out in order to elucidate the influence of the catalytic region residues during DHO oxidation.

  17. Evaluation of the protective effect of chemical additives in the oxidation of phenolic compounds catalysed by peroxidase.

    Science.gov (United States)

    Torres, Juliana Arriel; Chagas, Pricila Maria Batista; Silva, Maria Cristina; Dos Santos, Custódio Donizete; Corrêa, Angelita Duarte

    2016-01-01

    The use of oxidoredutive enzymes in removing organic pollutants has been the subject of much research. The oxidation of phenolic compounds in the presence of chemical additives has been the focus of this study. In this investigation, the influence of the additives polyethylene glycol and Triton X-100 was evaluated in the phenol oxidation, caffeic acid, chlorogenic acid and total phenolic compounds present in coffee processing wastewater (CPW) at different pH values, performed by turnip peroxidase and peroxidase extracted from soybean seed hulls. The influence of these additives was observed only in the oxidation of phenol and caffeic acid. In the oxidation of other studied phenolic compounds, the percentage of oxidation remained unchanged in the presence of these chemical additives. In the oxidation of CPW in the presence of additives, no change in the oxidation of phenolic compounds was observed. Although several studies show the importance of evaluating the influence of additives on the behaviour of enzymes, this study found a positive response from the economic point of view for the treatment of real wastewater, since the addition of these substances showed no influence on the oxidation of phenolic compounds, which makes the process less costly. PMID:26502790

  18. Heterogeneous Partial (ammOxidation and Oxidative Dehydrogenation Catalysis on Mixed Metal Oxides

    Directory of Open Access Journals (Sweden)

    Jacques C. Védrine

    2016-01-01

    Full Text Available This paper presents an overview of heterogeneous partial (ammoxidation and oxidative dehydrogenation (ODH of hydrocarbons. The review has been voluntarily restricted to metal oxide-type catalysts, as the partial oxidation field is very broad and the number of catalysts is quite high. The main factors of solid catalysts for such reactions, designated by Grasselli as the “seven pillars”, and playing a determining role in catalytic properties, are considered to be, namely: isolation of active sites (known to be composed of ensembles of atoms, Me–O bond strength, crystalline structure, redox features, phase cooperation, multi-functionality and the nature of the surface oxygen species. Other important features and physical and chemical properties of solid catalysts, more or less related to the seven pillars, are also emphasized, including reaction sensitivity to metal oxide structure, epitaxial contact between an active phase and a second phase or its support, synergy effect between several phases, acid-base aspects, electron transfer ability, catalyst preparation and activation and reaction atmospheres, etc. Some examples are presented to illustrate the importance of these key factors. They include light alkanes (C1–C4 oxidation, ethane oxidation to ethylene and acetic acid on MoVTe(SbNb-O and Nb doped NiO, propene oxidation to acrolein on BiMoCoFe-O systems, propane (ammoxidation to (acrylonitrile acrylic acid on MoVTe(SbNb-O mixed oxides, butane oxidation to maleic anhydride on VPO: (VO2P2O7-based catalyst, and isobutyric acid ODH to methacrylic acid on Fe hydroxyl phosphates. It is shown that active sites are composed of ensembles of atoms whose size and chemical composition depend on the reactants to be transformed (their chemical and size features and the reaction mechanism, often of Mars and van Krevelen type. An important aspect is the fact that surface composition and surface crystalline structure vary with reaction on stream until

  19. Formation of imines by selective gold-catalysed aerobic oxidative coupling of alcohols and amines under ambient conditions

    DEFF Research Database (Denmark)

    Kegnæs, Søren; Mielby, Jerrik Jørgen; Mentzel, Uffe Vie;

    2010-01-01

    The formation of imines by aerobic oxidative coupling of mixtures of alcohols and amines was studied using gold nanoparticles supported on titanium dioxide, TiO2, as a heterogeneous catalyst. The reactions were performed at ambient conditions (room temperature and atmospheric pressure) and occurred...

  20. Nucleophile-directed selectivity towards linear carbonates in the niobium pentaethoxide-catalysed cycloaddition of CO2 and propylene oxide

    KAUST Repository

    Dutta, Barnali

    2014-01-01

    Homoleptic Nb-complexes combined with selected organic nucleophiles generate very active catalytic systems for the cycloaddition of propylene oxide and CO2 under ambient conditions. An unprecedented reaction pathway towards an acyclic organic carbonate is observed when extending the study to [Nb(OEt)5] in combination with 4-dimethylamino-pyridine (DMAP) or tetra-n-butylammonium bromide (TBAB). Mechanistic insights of the reaction are provided based on experimental and spectroscopic evidences. This journal is © the Partner Organisations 2014.

  1. Controlling activity and selectivity using water in the Au-catalysed preferential oxidation of CO in H2

    Science.gov (United States)

    Saavedra, Johnny; Whittaker, Todd; Chen, Zhifeng; Pursell, Christopher J.; Rioux, Robert M.; Chandler, Bert D.

    2016-06-01

    Industrial hydrogen production through methane steam reforming exceeds 50 million tons annually and accounts for 2–5% of global energy consumption. The hydrogen product, even after processing by the water–gas shift, still typically contains ∼1% CO, which must be removed for many applications. Methanation (CO + 3H2 → CH4 + H2O) is an effective solution to this problem, but consumes 5–15% of the generated hydrogen. The preferential oxidation (PROX) of CO with O2 in hydrogen represents a more-efficient solution. Supported gold nanoparticles, with their high CO-oxidation activity and notoriously low hydrogenation activity, have long been examined as PROX catalysts, but have shown disappointingly low activity and selectivity. Here we show that, under the proper conditions, a commercial Au/Al2O3 catalyst can remove CO to below 10 ppm and still maintain an O2-to-CO2 selectivity of 80–90%. The key to maximizing the catalyst activity and selectivity is to carefully control the feed-flow rate and maintain one to two monolayers of water (a key CO-oxidation co-catalyst) on the catalyst surface.

  2. Optical conductivity of partially oxidized graphene from first principles

    Energy Technology Data Exchange (ETDEWEB)

    Nasehnia, F., E-mail: f.nasehnia@gmail.com; Seifi, M., E-mail: Seifi@guilan.ac.ir [Department of Physics, University of Guilan, P. O. Box 41335-1914, Rasht (Iran, Islamic Republic of)

    2015-07-07

    We investigate the geometry, electronic structure, and optical properties of partially oxidized graphene using density functional theory. Our calculations show that oxygen atoms are chemisorbed on graphene plane and distort carbon atoms vertically, with almost no change in the in-plane structure. The ground state configurations for different oxygen coverages ranging from 2% to 50% (O/C ratio) are calculated and show the strong tendency of oxygen adatoms to aggregate and form discrete islands on graphene plane. It is found that the opened band gap due to oxygen functionalization depends on the oxygen density and the adsorption configuration. The gap is not significant for oxygen densities lower than 8%. The optical conductivities are calculated in the infrared, visible, and ultraviolet regions and show different characteristic features depending on the degree of oxidation. These results imply that optical measurement techniques can be employed to monitor oxidation (or reduction) process as contact-free methods.

  3. Optical conductivity of partially oxidized graphene from first principles

    International Nuclear Information System (INIS)

    We investigate the geometry, electronic structure, and optical properties of partially oxidized graphene using density functional theory. Our calculations show that oxygen atoms are chemisorbed on graphene plane and distort carbon atoms vertically, with almost no change in the in-plane structure. The ground state configurations for different oxygen coverages ranging from 2% to 50% (O/C ratio) are calculated and show the strong tendency of oxygen adatoms to aggregate and form discrete islands on graphene plane. It is found that the opened band gap due to oxygen functionalization depends on the oxygen density and the adsorption configuration. The gap is not significant for oxygen densities lower than 8%. The optical conductivities are calculated in the infrared, visible, and ultraviolet regions and show different characteristic features depending on the degree of oxidation. These results imply that optical measurement techniques can be employed to monitor oxidation (or reduction) process as contact-free methods

  4. Reactor modeling and process analysis for partial oxidation of natural gas

    NARCIS (Netherlands)

    Albrecht, Bogdan Alexandru

    2004-01-01

    This thesis analyses a novel process of partial oxidation of natural gas and develops a numerical tool for the partial oxidation reactor modeling. The proposed process generates syngas in an integrated plant of a partial oxidation reactor, a syngas turbine and an air separation unit. This is called

  5. Kinetic, mechanistic and spectral investigation of ruthenium (III)-catalysed oxidation of atenolol by alkaline permanganate (stopped-flow technique)

    Indian Academy of Sciences (India)

    Rahamatalla M Mulla; Gurubasavaraj C Hiremath; Sharanappa T Nandibewoor

    2005-01-01

    Kinetics of ruthenium (III) catalyzed oxidation of atenolol by permanganate in alkaline medium at constant ionic strength of 0.30 mol dm3 has been studied spectrophotometrically using a rapid kinetic accessory. Reaction between permanganate and atenolol in alkaline medium exhibits 1 : 8 stoichiometry (atenolol : KMnO4). The reaction shows first-order dependence on [permanganate] and [ruthenium (III)] and apparently less than unit order on both atenolol and alkali concentrations. Reaction rate decreases with increase in ionic strength and increases with decreasing dielectric constant of the medium. Initial addition of reaction products does not affect the rate significantly. A mechanism involving the formation of a complex between catalyst and substrate has been proposed. The active species of ruthenium (III) is understood as [Ru(H2O)5OH]2+. The reaction constants involved in the different steps of mechanism are calculated. Activation parameters with respect to the slow step of the mechanism are computed and discussed and thermodynamic quantities are also calculated.

  6. Chelation-assisted Pd-catalysed ortho-selective oxidative C-H/C-H cross-coupling of aromatic carboxylic acids with arenes and intramolecular Friedel-Crafts acylation: one-pot formation of fluorenones.

    Science.gov (United States)

    Sun, Denan; Li, Bijin; Lan, Jingbo; Huang, Quan; You, Jingsong

    2016-03-01

    Pd-Catalysed ortho-selective oxidative C-H/C-H cross-coupling of aromatic carboxylic acids with arenes and subsequent intramolecular Friedel-Crafts acylation has been accomplished for the first time through a chelation-assisted C-H activation strategy. Starting from the readily available substrates, a variety of fluorenone derivatives are obtained in one pot. The direct use of naturally occurring carboxylic acid functionalities as directing groups avoids unnecessary steps for installation and removal of an extra directing group. PMID:26861768

  7. Ruthenium/1,1 '-Bis(diphenylphosphino)ferrocene-Catalysed Oppenauer Oxidation of Alcohols and Lactonisation of alpha,omega-Diols using Methyl Isobutyl Ketone as Oxidant

    NARCIS (Netherlands)

    Nicklaus, Celine M.; Phua, Pim Huat; Buntara, Teddy; Noel, Sebastien; Heeres, Hero J.; de Vries, Johannes G.

    2013-01-01

    A number of ruthenium catalysts, made in situ from [Ru(p-cymene)Cl-2](2) and various monodentate and bidentate phosphorus ligands were screened in the double Oppenauer oxidation of 1,6-hexanediol to caprolactone using methyl isobutyl ketone as oxidant and potassium carbonate as base. The catalyst ba

  8. Partial oxidation of methane by pulsed corona discharges

    Science.gov (United States)

    Hoeben, W. F. L. M.; Boekhoven, W.; Beckers, F. J. C. M.; van Heesch, E. J. M.; Pemen, A. J. M.

    2014-09-01

    Pulsed corona-induced partial oxidation of methane in humid oxygen or carbon dioxide atmospheres has been investigated for future fuel synthesis applications. The obtained product spectrum is wide, i.e. saturated, unsaturated and oxygen-functional hydrocarbons. The generally observed methane conversion levels are 6-20% at a conversion efficiency of about 100-250 nmol J-1. The main products are ethane, ethylene and acetylene. Higher saturated hydrocarbons up to C6 have been detected. The observed oxygen-functional hydrocarbons are methanol, ethanol and lower concentrations of aldehydes, ketones, dimethylether and methylformate. Methanol seems to be exclusively produced with CH4/O2 mixtures at a maximum production efficiency of 0.35 nmol J-1. CH4/CO2 mixtures appear to yield higher hydrocarbons. Carboxylic acids appear to be mainly present in the aqueous reactor phase, possibly together with higher molecular weight species.

  9. Method for improving catalyst function in auto-thermal and partial oxidation reformer-based processors

    Science.gov (United States)

    Ahmed, Shabbir; Papadias, Dionissios D.; Lee, Sheldon H.D.; Ahluwalia, Rajesh K.

    2014-08-26

    The invention provides a method for reforming fuel, the method comprising contacting the fuel to an oxidation catalyst so as to partially oxidize the fuel and generate heat; warming incoming fuel with the heat while simultaneously warming a reforming catalyst with the heat; and reacting the partially oxidized fuel with steam using the reforming catalyst.

  10. Microreactor for the Catalytic Partial Oxidation of Methane

    Institute of Scientific and Technical Information of China (English)

    Widodo Wahyu Puwanto; Yuswan Muharam

    2006-01-01

    Fixed-bed reactors for the partial oxidation of methane to produce synthetic gas still pose hotspot problems. An alternative reactor, which is known as the shell-and-tube-typed microreactor, has been developed to resolve these problems. The microreactor consists of a 1 cm outside-diameter, 0.8 cm insidediameter and 11 cm length tube, and a 1.8 cm inside-diameter shell. The tube is made of dense alumina and the shell is made of quartz. Two different methods dip and spray coating were performed to line the tube side with the LaNixOy catalyst. Combustion and reforming reactions take place simultaneously in this reactor. Methane is oxidized in the tube side to produce flue gases (CO2 and H2O) which flow counter-currently and react with the remaining methane in the shell side to yield synthesis gas. The methane conversion using the higher-loading catalyst spray-coated tube reaches 97% at 700 ℃, whereas that using the lower-loading catalyst dip-coated tube reaches only 7.78% because of poor adhesion between the catalyst film and the alumina support. The turnover frequencies (TOFs) using the catalyst spray-and 900 ℃ provides better performance than that at 1250 ℃ because sintering reduces the surface-area. The hydrogen to carbon monoxide ratio produced by the spray-coated catalyst is greater than the stoichiometric ratio, which is caused by carbon deposition through methane cracking or the Boudouard reaction.

  11. Deactivation kinetics of V/Ti-oxide in toluene partial oxidation

    OpenAIRE

    Bulushev, D. A.; Reshetnikov, S. I.; Kiwi-Minsker, L; Renken, A.

    2001-01-01

    The deactivation kinetics of a V/Ti oxide catalyst were studied in partial oxidn. of toluene to PhCHO and PhCO2H at 523-573 K. The catalyst consists of a monolayer of VOx species, and after oxidative pretreatment, contains isolated monomeric and polymeric metavanadate-like vanadia species under dehydrated conditions as was shown by FT Raman spectroscopy. Under the reaction conditions via in situ DRIFTS, fast formation of adsorbed carboxylate and benzoate species was obsd. accompanied by disap...

  12. Partially Oxidized Sub-10 nm MnO Nanocrystals with High Activity for Water Oxidation Catalysis

    Science.gov (United States)

    Jin, Kyoungsuk; Chu, Arim; Park, Jimin; Jeong, Donghyuk; Jerng, Sung Eun; Sim, Uk; Jeong, Hui-Yun; Lee, Chan Woo; Park, Yong-Sun; Yang, Ki Dong; Kumar Pradhan, Gajendra; Kim, Donghun; Sung, Nark-Eon; Hee Kim, Sun; Nam, Ki Tae

    2015-05-01

    The oxygen evolution reaction (OER) is considered a major bottleneck in the overall water electrolysis process. In this work, highly active manganese oxide nano-catalysts were synthesized via hot injection. Facile surface treatment generated Mn(III) species on monodisperse 10 nm MnO nanocrystals (NCs). Size dependency of MnO NCs on OER activity was also investigated. Surprisingly, the partially oxidized MnO NCs only required 530 mV @ 5 mA cm-2 under near neutral conditions.

  13. Partially Oxidized Sub-10 nm MnO Nanocrystals with High Activity for Water Oxidation Catalysis

    OpenAIRE

    Kyoungsuk Jin; Arim Chu; Jimin Park; Donghyuk Jeong; Sung Eun Jerng; Uk Sim; Hui-Yun Jeong; Chan Woo Lee; Yong-Sun Park; Ki Dong Yang; Gajendra Kumar Pradhan; Donghun Kim; Nark-Eon Sung; Sun Hee Kim; Ki Tae Nam

    2015-01-01

    The oxygen evolution reaction (OER) is considered a major bottleneck in the overall water electrolysis process. In this work, highly active manganese oxide nano-catalysts were synthesized via hot injection. Facile surface treatment generated Mn(III) species on monodisperse 10 nm MnO nanocrystals (NCs). Size dependency of MnO NCs on OER activity was also investigated. Surprisingly, the partially oxidized MnO NCs only required 530 mV @ 5 mA cm−2 under near neutral conditions.

  14. Catalytic performance of cerium iron complex oxides for partial oxidation of methane to synthesis gas

    Institute of Scientific and Technical Information of China (English)

    LI Kongzhai; WANG Hua; WEI Yonggang; LIU Mingchun

    2008-01-01

    The cerium iron complex oxides oxygen carder was prepared by the co-precipitation method. The reactions between methane and lattice oxygen from the complex oxides were investigated in a fixed micro-reactor system. The reduced oxygen carrier could be re-oxidized by air and its initial state could be restored. The characterizations of the oxygen carriers were studied using XRD, O2-TPD, and H2-TPR. The results showed that the bulk lattice oxygen of CeO2-Fe2O3 was found to be suitable for the partial oxidation of methane to synthesis gas. There were two kinds of oxygen species on the oxygen carder: the stronger oxygen species that was responsible for the complete oxidation of methane, and the weaker oxygen species (bulk lattice oxygen) that was responsible for the selective oxidation of methane to CO and H2 at a higher temperature. Then, the lost bulk lattice oxygen could be selectively supplemented by air re-oxidation at an appropriate reaction con-dition. CeFeO3 appeared on the oxygen carrier after 10 successive redox cycles, however, it was not bad for the selectivity of CO and H2.

  15. Generation of synthesis gas by partial oxidation of natural gas in a gas turbine

    NARCIS (Netherlands)

    Cornelissen, R.; Tober, E.; Kok, J.B.W.; Meer, van der T.H.

    2006-01-01

    The application of partial oxidation in a gas turbine (PO-GT) in the production of synthesis gas for methanol production is explored. In PO-GT, methane is compressed, preheated, partial oxidized and expanded. For the methanol synthesis a 12% gain in thermal efficiency has been calculated for the PO-

  16. Partial oxidation of methane over bimetallic copper- and nickel-actinide oxides (Th, U)

    International Nuclear Information System (INIS)

    The study of partial oxidation of methane (POM) over bimetallic nickel- or copper-actinide oxides was undertaken. Binary intermetallic compounds of the type AnNi2 (An = Th, U) and ThCu2 were used as precursors and the products (2NiO.UO3, 2NiO.ThO2 and 2CuO.ThO2) characterized by means of X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy and temperature-programmed reduction. The catalysts were active and selective for the conversion of methane to H2 and CO and stable for a period of time of ∼18 h on stream. The nickel catalysts were more active and selective than the copper catalyst and, under the same conditions, show a catalytic behaviour comparable to that of a platinum commercial catalyst, 5 wt% Pt/Al2O3. The catalytic activity increases when uranium replaces thorium and the selectivity of this type of materials is clearly different from that of single metal oxides and/or mechanical mixtures. The good catalytic behaviour of the bimetallic copper- and nickel-actinide oxides was attributed to an unusual interaction between copper or nickel oxide and the actinide oxide phase as showed by H2-TPR, XPS and Raman analysis of the catalysts before and after reaction.

  17. A basic approach to evaluate methane partial oxidation catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Parmaliana, A. (Universita degli Studi di Messina (Italy)); Frusteri, F.; Mezzapica, A.; Micelli, D.; Giordano, N. (Instituto CNR-TAE, Messina (Italy)); Scurrell, M.S. (CSIR, Pretoria (South Africa))

    1993-09-01

    The partial oxidation of methane to formaldehyde by molecular oxygen on silica and silica-supported oxide catalysts has been investigated at a pressure of 1.7 bar in the temperature range 520-650[degrees]C by using a batch reactor with external recycle. The effects of reactor diameter, recycle flow rate, catalyst weight, and methane-to-oxygen ratio on the catalyst activity have been outlined. By performing several blank tests with an empty and a quartz-filled reactor, it has been demonstrated that the gas-phase reaction does not affect the catalytic pathways. Reasons for controversial results reported previously are discussed. They lie in the lack of an adequate experimental approach and in the generally adopted rule to evaluate the catalytic activity at differential conditions in order to push the HCHO selectivity to high values. The approach presented here allows one to evaluate the catalytic activity by performing tests at quasi-zero conversion per mass but at a finite extent of conversion. The need to express the catalytic activity as space time yield (STY) to HCHO (g[center dot]kg[sub cat][sup [minus]1][center dot]h[sup [minus]1]) is presented. The reactivities of various commercial SiO[sub 2] samples obtained by precipitation, sol-gel, and pyrolysis methods have been determined. The fact that the nature and source of silica has a marked effect on STY, previously observed for reaction at 520[degrees]C, has been confirmed for operation at 550-650[degrees]C. Highest STYs are found with precipitated silica samples. In fact, at 650[degrees]C with such precipitated SiO[sub 2] a STY to HCHO of 303 g[center dot] kg[sub cat][sup [minus]1] [center dot] H[sup [minus]1] has been obtained. Incorporation of molybdena depresses the STY value for the precipitated silica but enhances the STY of bare fumed silica. In contrast, addition of vanadia to either precipitated or fumed silicas leads to higher STY values. 29 refs., 6 figs., 8 tabs.

  18. Autothermal and partial oxidation reformer-based fuel processor, method for improving catalyst function in autothermal and partial oxidation reformer-based processors

    Science.gov (United States)

    Ahmed, Shabbir; Papadias, Dionissios D.; Lee, Sheldon H. D.; Ahluwalia, Rajesh K.

    2013-01-08

    The invention provides a fuel processor comprising a linear flow structure having an upstream portion and a downstream portion; a first catalyst supported at the upstream portion; and a second catalyst supported at the downstream portion, wherein the first catalyst is in fluid communication with the second catalyst. Also provided is a method for reforming fuel, the method comprising contacting the fuel to an oxidation catalyst so as to partially oxidize the fuel and generate heat; warming incoming fuel with the heat while simultaneously warming a reforming catalyst with the heat; and reacting the partially oxidized fuel with steam using the reforming catalyst.

  19. Influence of the Oxygen Partial Pressure on the Oxidation of Inconel 617 Alloy at High Temperature

    International Nuclear Information System (INIS)

    Ni-based superalloy Inconel 617 (IN617) is one of the main candidate structural materials for high temperature components (heat exchanger) of the gas-cooled fast reactor (GFR), a possible candidate for generation IV nuclear reactor. The material in operating conditions will be exposed to impure He at a temperature of around 850 C. The impurities are expected to be oxidizing (such as O2, H2O) but since no feedback experience is available for this type of reactor, the level of impurities is completely unknown. Hence, an attempt has been made to understand the influence of oxygen partial pressure on oxide composition and on the oxidation mechanisms of IN617 at 850 C. To achieve this, oxidation tests were performed at 3 different range of partial pressure: 10-5, 0. 2 and 200 mbar. Tests were performed from 1 h to 28 days and the obtained oxide layers were characterized using MEB, EDX, XPS, XRD and GD-OES. The oxide layers were mainly composed of chromia containing TiO2 and thickening with time. Aluminium oxide formed internally. Other oxides were detected in the scale, such as NiO, CoO, MoO3 and MnO2, except for the lowest oxygen partial pressure experiments, where a selective oxidation took place. The scale-growth mechanism was cationic for low and medium oxygen partial pressure conditions. A growth following a transient oxidation mechanism was observed for high oxygen partial pressure. (authors)

  20. Mechanistic Investigation of Molybdate-Catalysed Transfer Hydrodeoxygenation

    DEFF Research Database (Denmark)

    Larsen, Daniel Bo; Petersen, Allan Robertson; Dethlefsen, Johannes Rytter;

    2016-01-01

    The molybdate-catalysed transfer hydrodeoxygenation (HDO) of benzyl alcohol to toluene driven by oxidation of the solvent isopropyl alcohol to acetone has been investigated by using a combination of experimental and computational methods. A Hammett study that compared the relative rates for the t...

  1. Hydrogen production by partial oxidative gasification of biomass and its model compounds in supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Hui; Lu, Youjun; Guo, Liejin; Cao, Changqing; Zhang, Ximin [State Key Laboratory of Multiphase Flow in Power Engineering, Xi' an Jiaotong University, Xi' an 710049 (China)

    2010-04-15

    Partial oxidative gasification in supercritical water is a new technology for hydrogen production from biomass. Firstly in this paper, supercritical water partial oxidative gasification process was analyzed from the perspective of theory and chemical equilibrium gaseous product was calculated using the thermodynamic model. Secondly, the influence of oxidant equivalent ratio on partial oxidative gasification of model compounds (glucose, lignin) and real biomass (corn cob) in supercritical water was investigated in a fluidized bed system. Experimental results show that oxidant can improve the gasification efficiency, and an appropriate addition of oxidant can improve the yield of hydrogen in certain reaction condition. When ER equaled 0.4, the gasification efficiency of lignin was 3.1 times of that without oxidant. When ER equaled 0.1, the yield of hydrogen from lignin increased by 25.8% compared with that without oxidant. Thirdly, the effects of operation parameters including temperature, pressure, concentration, and flow rate of feedstock on the gasification were investigated. The optimal operation parameters for supercritical water partial oxidative gasification were obtained. (author)

  2. Direct Partial Oxidation of Natural Gas to Liquid Chemicals

    DEFF Research Database (Denmark)

    Rasmussen, Christian Lund

    2007-01-01

    Direkte delvis oxidation af naturgas til flydende kemikalier er en attraktiv industriel proces, hvor naturgas omdannes til stoffer; primært methanol (CH3OH) som let kan transporteres over store afstande. Omdannelsen sker i en simpel et-trinsproces under højt tryk, lave forbrændingstemperaturer, s...

  3. Direct partial oxidation of methane to methanol: Reaction zones and role of catalyst location

    Institute of Scientific and Technical Information of China (English)

    Qijian Zhang; Dehua He; Qiming Zhu

    2008-01-01

    Direct partial oxidation of methane to methanol was investigated in a specially designed reactor. Methanol yield of about 7%-8% was obtained in gas phase partial oxidation. It was proposed that the reactor could be divided into three reaction zones, namely pre-reaction zone, fierce reaction zone, and post-reaction zone, when the temperature was high enough to initiate a reaction. The oxidation of methane proceeded and was completed mostly in the fierce reaction zone. When the reactant mixture entered the post-reaction zone, only a small amount of produced methanol would bring about secondary reactions, because molecular oxygen had been exhausted in the fierce reaction zone. A catalyst, if necessary, should be placed either in the pre-reaction zone, to initiate a partial oxidation reaction at a lower temperature, or in the fierce reaction zone to control the homogeneous free radical reaction.

  4. Study of propane partial oxidation on vanadium-containing catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Komashko, G.A.; Khalamejda, S.V.; Zazhigalov, V.A. [AN Ukrainskoj SSR, Kiev (Ukraine). Inst. Fizicheskoj Khimii

    1998-12-31

    The present results indicate that maximum selectivity to acrylic acid can be reached over V-P-Zr-O catalysts. When the hydrocarbon concentration is 5.1 vol.% the selectivity is about 30% at quite high paraffin conversion. Conclusively, some explanations to the observed facts can be given. The V-P-O catalyst promotion with lanthanum by means of mechanochemical treatment is distinguished by the additive uniform spreading all over the matrix surface. Such twophase system is highly active in propane conversion (lanthanum oxide) and further oxidation of the desired products. The similar properties are attributed to V-P-Bi-La-O catalyst. Bismuth, tellurium and zirconium additives having clearly defined acidic properties provoke the surface acidity strengthening and make easier desorption of the acidic product (acrylic acid) from the surface lowering its further oxidation. Additionally, since bismuth and zirconium are able to form phosphates and, according to, to create space limitations for the paraffin molecule movement out of the active group boundaries, this can be one more support in favour of the selectivity increase. With this point of view very interesting results were obtained. It has been shown that the more limited the size of the vanadium unit, the higher the selectivity is. Monoclinic phase AV{sub 2}P{sub 2}O{sub 10} which consists in clusters of four vanadium atoms is sensibly more reactive than the orthorhombic phase consists in V{sub {infinity}} infinite chains. (orig.)

  5. The nitric oxide redox sibling nitroxyl partially circumvents impairment of platelet nitric oxide responsiveness.

    Science.gov (United States)

    Dautov, R F; Ngo, D T M; Licari, G; Liu, S; Sverdlov, A L; Ritchie, R H; Kemp-Harper, B K; Horowitz, J D; Chirkov, Y Y

    2013-11-30

    Impaired platelet responsiveness to nitric oxide (NO resistance) is a common characteristic of many cardiovascular disease states and represents an independent risk factor for cardiac events and mortality. NO resistance reflects both scavenging of NO by superoxide (O2(-)), and impairment of the NO receptor, soluble guanylate cyclase (sGC). There is thus an urgent need for circumvention of NO resistance in order to improve clinical outcomes. Nitroxyl (HNO), like NO, produces vasodilator and anti-aggregatory effects, largely via sGC activation, but is not inactivated by O2(-). We tested the hypothesis that HNO circumvents NO resistance in human platelets. In 57 subjects with or without ischemic heart disease, platelet responses to the HNO donor isopropylamine NONOate (IPA/NO) and the NO donor sodium nitroprusside (SNP) were compared. While SNP (10μM) induced 29±3% (p<0.001) inhibition of platelet aggregation, IPA/NO (10μM) caused 75±4% inhibition (p<0.001). In NO-resistant subjects (n=28), the IPA/NO:SNP response ratio was markedly increased (p<0.01), consistent with partial circumvention of NO resistance. Similarly, cGMP accumulation in platelets was greater (p<0.001) with IPA/NO than with SNP stimulation. The NO scavenger carboxy-PTIO (CPTIO, 200μM) inhibited SNP and IPA/NO responses by 92±7% and 17±4% respectively (p<0.001 for differential inhibition), suggesting that effects of IPA/NO are only partially NO-mediated. ODQ (10μM) inhibited IPA/NO responses by 36±8% (p<0.001), consistent with a contribution of sGC/haem to IPA/NO inhibition of aggregation. There was no significant relationship between whole blood ROS content and IPA/NO responses. Thus the HNO donor IPA/NO substantially circumvents platelet NO resistance while acting, at least partially, as a haem-mediated sGC activator.

  6. Oxidation of C/SiC Composites at Reduced Oxygen Partial Pressures

    Science.gov (United States)

    Opila, Elizabeth J.; Serra, Jessica

    2009-01-01

    Carbon-fiber reinforced SiC (C/SiC) composites are proposed for leading edge applications of hypersonic vehicles due to the superior strength of carbon fibers at high temperatures (greater than 1500 C). However, the vulnerability of the carbon fibers in C/SiC to oxidation over a wide range of temperatures remains a problem. Previous oxidation studies of C/SiC have mainly been conducted in air or oxygen, so that the oxidation behavior of C/SiC at reduced oxygen partial pressures of the hypersonic flight regime are less well understood. In this study, both carbon fibers and C/SiC composites were oxidized over a wide range of temperatures and oxygen partial pressures to facilitate the understanding and modeling of C/SiC oxidation kinetics for hypersonic flight conditions.

  7. Oxidation behavior of modified SUS316 (PNC316) stainless steel under low oxygen partial pressure

    International Nuclear Information System (INIS)

    Oxidation behaviors of modified SUS316 (PNC316) and SUS316 stainless steels were investigated under the low oxygen partial pressure of 10-31-10-22 atm at 600-800 deg. C. Oxygen uptake by these materials parabolically increased with time, and the kinetic rate constants depended on both oxygen partial pressure and temperature. Thus, semi-empirical equations of the parabolic rate constants were obtained to be 2.70x104exp(-109/RT)PO20.279 for PNC316 and 9.23x104exp(-98/RT)PO20.313 for SUS316. For the duplex layer formed under the low oxygen partial pressure, the inner layer consisted of such oxides as Cr2O3 and FeCr2O4, while the outer layer consisted of non-oxidized α-Fe. Furthermore, oxidation along the grain boundaries was observed for samples oxidized for a long time. From the point of view of fuel cladding chemical interaction evaluation at high burn-up fuel for fast reactors, it is interesting that formation of non-oxidized α-Fe was observed under the low oxygen partial pressure

  8. Partial oxidation of methane in a temperature-controlled dielectric barrier discharge reactor

    KAUST Repository

    Zhang, Xuming

    2015-01-01

    We studied the relative importance of the reduced field intensity and the background reaction temperature in the partial oxidation of methane in a temperature-controlled dielectric barrier discharge reactor. We obtained important mechanistic insight from studying high-temperature and low-pressure conditions with similar reduced field intensities. In the tested range of background temperatures (297 < T < 773 K), we found that the conversion of methane and oxygen depended on both the electron-induced chemistry and the thermo-chemistry, whereas the chemical pathways to the products were overall controlled by the thermo-chemistry at a given temperature. We also found that the thermo-chemistry enhanced the plasma-assisted partial oxidation process. Our findings expand our understanding of the plasma-assisted partial oxidation process and may be helpful in the design of cost-effective plasma reformers. © 2014 The Combustion Institute.

  9. The influence of partial oxidation mechanisms on tar destruction in TwoStage biomass gasification

    DEFF Research Database (Denmark)

    Ahrenfeldt, Jesper; Egsgaard, Helge; Stelte, Wolfgang;

    2013-01-01

    TwoStage gasification of biomass results in almost tar free producer gas suitable for multiple end-use purposes. In the present study, it is investigated to what extent the partial oxidation process of the pyrolysis gas from the first stage is involved in direct and in-direct tar destruction...... adsorption and determined by stable isotope dilution analysis. The results have shown that partial oxidation reduces and converts primary tars into low molecular weight, polycyclic aromatic hydrocarbons (PAHs), primarily naphthalene. At temperatures above 950°C practically all phenol is converted...

  10. Generation of synthesis gas by partial oxidation of natural gas in a gas turbine

    International Nuclear Information System (INIS)

    The application of partial oxidation in a gas turbine (PO-GT) in the production of synthesis gas for methanol production is explored. In PO-GT, methane is compressed, preheated, partial oxidized and expanded. For the methanol synthesis a 12% gain in thermal efficiency has been calculated for the PO-GT process, while the product cost decrease with 7%. For DME synthesis simular results are achieved. More development on the reactor and turbine are needed to implement this process in the industry

  11. Hg (II Catalysed Oxidation of D-Arabinose and D-Mannose by Acidic Solution of Potassium Permanganate: Kinetics and Mechanism

    Directory of Open Access Journals (Sweden)

    *1R. Naz

    2014-09-01

    Full Text Available The kinetics of Hg (II catalyzed oxidation of D-Arabinose (Ara and D-Mannose (Man by potassium permanganate in acidic medium have been studied spectrophotometrically in the temperature range 30-50oC. The reactions exhibit first order kinetics with respect to [Man] and [MnO4-] while second order with [Ara]. The reaction rates were found to be unaffected by the change in [H+]. It has been observed that Hg (II catalyzed the reaction but as the [Hg(II] increases, reaction rate becomes independent. Negligible effect of ionic strength (μ on the rate of oxidation has also been noted which supports the presence of at least one neutral specie in the rate determining step. The rate of oxidation was influenced by the change in temperature. Various activation parameters have been calculated. Formic acid and erythronic acid were identified as main oxidation product in case of arabinose while for mannose formic acid and arabinonic acid were identified. A mechanism consistent with the above findings has also been proposed.

  12. Energetic analysis of gasification of biomass by partial oxidation in supercritical water

    Institute of Scientific and Technical Information of China (English)

    Qingqing Guan; Chaohai Wei; Xinsheng Chai; Ping Ning; Senlin Tian; Junjie Gu; Qiuling Chen; Rongrong Miao

    2015-01-01

    Partial oxidation gasification in supercritical water could produce fuel gases (such as H2, CO and CH4) and signif-icantly reduce the energy consumption. In this work, an energetic model was developed to analyze the partial oxidative gasification of biomass (glucose and lignin) in supercritical water and the related key factors on which gasification under autothermal condition depended upon. The results indicated that the oxidant equiva-lent ratio (ER) should be over 0.3 as the concern about energy balance but less than 0.6 as the concern about fuel gas production. Feedstocks such as glucose and lignin also had different energy recovery efficiency. For ma-terials which can be efficiently gasified, the partial oxidation might be a way for energy based on the combustion of fuel gases. Aromatic materials such as lignin and coal are more potential since partial oxidation could produce similar amount of fuel gases as direct gasification and offer additional energy. Energy recovered pays a key role to achieve an autothermal process. Keeping heat exchanger efficiency above 80%and heat transfer coefficient below 15 kJ·s−1 is necessary to maintain the autothermal status. The results also indicated that the biomass loading should be above 15%but under 20%for an autothermal gasification, since the increase of biomass loading could improve the energy supplied but decrease the efficiency of gasification and gaseous yields. In general, some specific conditions exist among different materials.

  13. Partial oxidation of methane to synthesis gas in a dual catalyst bed system combining irreducible oxide and metallic catalysts

    NARCIS (Netherlands)

    Zhu, J.J.; Rahuman, M.S.M.M.; Ommen, van J.G.; Lefferts, L.

    2004-01-01

    Operation of partial oxidation of methane to synthesis gas over yttrium-stabilized zirconia (YSZ) at very high temperatures (¿900°C) slightly improves the selectivity to synthesis gas, which is caused by some activity of YSZ for steam and dry reforming of methane. LaCoO3 perovskite is not active in

  14. Simulation of a fuel reforming system based on catalytic partial oxidation

    Science.gov (United States)

    Hohn, Keith L.; DuBois, Terry

    Catalytic partial oxidation (CPO) has potential for producing hydrogen that can be fed to a fuel cell for portable power generation. In order to be used for this purpose, catalytic partial oxidation must be combined with other processes, such as water-gas shift and preferential oxidation, to produce hydrogen with minimal carbon monoxide. This paper evaluates the use of catalytic partial oxidation in an integrated system for conversion of a military logistic fuel, JP-8, to high-purity hydrogen. A fuel processing system using CPO as the first processing step is simulated to understand the trade-offs involved in using CPO. The effects of water flow rate, CPO reactor temperature, carbon to oxygen ratio in the CPO reactor, temperature of preferential oxidation, oxygen to carbon ratio in the preferential oxidation reactor, and temperature for the water-gas shift reaction are evaluated. The possibility of recycling water from the fuel cell for use in fuel processing is evaluated. Finally, heat integration options are explored. A process efficiency, defined as the ratio of the lower heating value of hydrogen to that of JP-8, of around 53% is possible with a carbon to oxygen ratio of 0.7. Higher efficiencies are possible (up to 71%) when higher C/O ratios are used, provided that olefin production can be minimized in the CPO reactor.

  15. Selective oxidation of benzyl alcohol with tert-butylhydroperoxide catalysed via Mn (II) 2, 2-bipyridine complexes immobilized over the mesoporous hexagonal molecular sieves (HMS)

    Indian Academy of Sciences (India)

    Vahid Mahdavi; Mahdieh Mardani

    2012-09-01

    A series ofMn(II)bipy complexes with different loading of Mn2+ supported on HMS was prepared. These samples were characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Thermogravimetric and Differential Scanning Calorimetry (TG-DSC), Ultraviolet and Visible spectra (UV-Vis) and Fourier transforms Infrared (FT-IR). The catalytic activity of the supportedMn(II)bipy complexes, [Mn(bipy)2]2+/HMS was evaluated in the oxidation of benzyl alcohol in the liquid phase using tert-butylhydroperoxide (TBHP) as an oxidant. The effects of Mn2+ loading and various solvents on the conversion and selectivity were studied. A second order function for the variation in catalytic activity with respect to the loading of Mn2+ ions in different catalyst samples was observed. The activity of the [Mn(bipy)2]2+/HMS catalyst differs with the type of the solvent and in this case, acetonitrile gives the best conversion results. The kinetic of benzyl alcohol oxidation was investigated at temperatures of 27, 46, 60, 75 and 90°C using [Mn(bipy)2]2+/HMS and excess TBHP. The order of reaction with respect to benzyl alcohol was determined to be pseudo-first order. The value of the apparent activation energy was also determined.

  16. Eco-friendly synthesis and characterization of Ni-Si nanoparticles mixed oxides as catalyst for partial oxidation of methane

    International Nuclear Information System (INIS)

    The nanoparticles of Ni-Si mixed oxides were prepared by co-precipitation method using nickel nitrate; Ni(NO3)2 6H2O and tetraethyl orthosilicate. The products were characterized by X-ray diffraction, transmission electron microscopy, and hydrogen temperature program reduction (H2-TPR). The results revealed that Ni-Si mixed oxides particles were obtained with average particle size 1-2 nm. The Ni-Si nanoparticles mixed oxides successfully catalyzed the partial oxidation of methane to hydrogen and carbon monoxide (Syn gas) using a fixed-bed reactor with about 92% activity and high selectivity. No coke formation and deactivation of catalyst were observed during the course of reaction. Particularly significant is the similar reactivity of this catalyst with that of Ni-Ce-Zr mixed oxides

  17. The Effects of CO2 Addition on the Partial Oxidation of Heptane for Hydrogen Generation

    Institute of Scientific and Technical Information of China (English)

    Ran RAN; Guo Xing XIONG; Shi Shan SHENG; Wei Shen YANG

    2004-01-01

    The effects of CO2 on the partial oxidation of heptane for hydrogen generation have been studied. Based on the experimental results and thermodynamic equilibrium calculations, the validity of CO2 addition to weaken the hot spots, and the feasibility of the autothermal operation are discussed.

  18. Modelling of a reverse flow catalytic membrane reactor for the partial oxidation of methane

    NARCIS (Netherlands)

    Smit, J.; Sint Annaland, van M.; Kuipers, J.A.M.

    2003-01-01

    Gas-To-Liquid (GTL) processes have great potential as alternative to conventional oil and coal processing for the production of liquid fuels. In GTL-processes the partial oxidation of methane (POM) is combined with the Fischer-Tropsch reaction. An important part of the investment costs of a conventi

  19. Partially oxidized polycyclic aromatic hydrocarbons show an increased bioavailability and biodegradability.

    NARCIS (Netherlands)

    Meulenberg, R.; Rijnaarts, H.H.M.; Doddema, H.J.; Field, J.A.

    1997-01-01

    Polycyclic aromatic hydrocarbons have a low water solubility and tend to adsorb on soil particles, which both result in slow bioremediation processes. Many microorganisms, known for their ability to degrade polycyclic aromatic hydrocarbons, only partially oxidize these compounds. White rot fungi, fo

  20. Development of a novel reactor concept for the partial oxidation of methane to syngas

    NARCIS (Netherlands)

    Smit, J.; Sint Annaland, van M.; Kuipers, J.A.M.

    2004-01-01

    The gas-to-liquid process, consisting of the partial oxidation of methane (POM) followed by the Fischer-Tropsch reaction, is a promising alternative to conventional oil processing for the production of liquid fuels. The cost of a conventional POM process is mainly determined by cryogenic air separat

  1. Kinetics of the partial oxidation of methanol over a Fe-Mo catalyst

    NARCIS (Netherlands)

    Deshmukh, S.A.R.K.; Sint Annaland, van M.; Kuipers, J.A.M.

    2005-01-01

    The intrinsic steady-state kinetics of the partial oxidation of methanol to formaldehyde over a commercial Fe-Mo catalyst has been studied experimentally in a differentially operated reactor at temperatures of 230¿260 °C, over a wide range of methanol and oxygen concentrations. The principal product

  2. Hg (II) Catalysed Oxidation of D-Arabinose and D-Mannose by Acidic Solution of Potassium Permanganate: Kinetics and Mechanism

    OpenAIRE

    R. Naz; *R. Azmat; Qamar, N; 3N. I. Siddiqi

    2014-01-01

    The kinetics of Hg (II) catalyzed oxidation of D-Arabinose (Ara) and D-Mannose (Man) by potassium permanganate in acidic medium have been studied spectrophotometrically in the temperature range 30-50oC. The reactions exhibit first order kinetics with respect to [Man] and [MnO4-] while second order with [Ara]. The reaction rates were found to be unaffected by the change in [H+]. It has been observed that Hg (II) catalyzed the reaction but as the [Hg(II)] increases, reaction rate becomes indepe...

  3. Oxygen partial pressure: a key to alloying and discovery in metal oxide--metal eutectic systems

    International Nuclear Information System (INIS)

    Control of oxygen partial pressure is essential in the directional solidification of oxide--metal eutectic composites by techniques involving gas-solid and gas-liquid interactions. The existence of end components in the eutectic composite is Po2 sensitive as are melt stoichiometry, solid phase compositions, and vapor losses due to oxidation-volatilization. Simple criteria are postulated which can aid the experimentalist in selecting the proper gas mixture for oxide--metal eutectic composite growth. The Cr2O3--Mo--Cr systems was used to verify certain aspects of the proposed criteria

  4. Mechanistic aspects of Os(VIII) catalysed oxidation of loop diuretic drug furosemide by Ag(III) periodate complex in aqueous alkaline medium

    Indian Academy of Sciences (India)

    Shweta J Malode; Nagaraj P Shetti; Sharanappa T Nandibewoor

    2012-03-01

    The kinetics of oxidation of a loop diuretic drug furosemide (Fur) by diperiodatoargentate(III) (DPA) has been investigated in the presence of osmium(VIII) (Os(VIII)) used as homogeneous catalyst in alkaline medium at a constant ionic strength of 0.20mol dm-3 spectrophotometrically attached with HI-TECH SFA-12 stopped flow accessory. The stoichiometry was 1:2 (Fur:DPA). The order of the reaction with respect to [DPA] was unity while the order with respect to [Fur] was less than unity over the concentration range studied. The rate increased with an increase in [OH−] and decreased with an increase in [IO$^{−}_{4}$]. The order with respect to [Os(VIII)] was unity. The oxidation products were identified as 2-(4-carboxy-2-oxo-but-3-enylamino)-4-chloro-5-sulfamoyl-benzoic acid and Ag(I). A suitable mechanism was proposed. The reaction constants involved in the different steps of the reaction mechanism were calculated. Kinetic experiments suggest that [Ag(H2IO6)(H2O)2] is the reactive silver(III) species and [OsO4(OH)2]2− is the reactive Os(VIII) species.

  5. Thermodynamic analysis of the partial oxidation of coke oven gas for indirect reduction of iron oxides in a blast furnace

    International Nuclear Information System (INIS)

    The partial oxidation of a COG (coke oven gas) in a blast furnace is examined in this work using thermodynamic analysis. LTIR and HTIR (Low-temperature and high-temperature indirect reduction) of iron oxides in a blast furnace are also studied. The influences of the reaction temperature, M/H (methane-to-hematite) ratio, and O/F (oxygen-to-fuel) ratio on CH4 conversion and iron oxide reduction are examined. Within the investigated ranges of the parameters, a higher reaction temperature is conducive to CH4 conversion, while at least 97.64% of Fe2O3 is reduced. In LTIR, Fe3O4 is the prime product, with a high level of solid carbon formation. The entire LTIR reaction is characterized by exothermic behavior, so that no additional heat is required to trigger COG partial oxidation and IR. In HTIR, increasing the reaction temperature facilitates CO-based IR and suppresses H2-based IR. A higher temperature produces more Fe, so as to enhance the iron oxide reduction reactions; meanwhile, the FeO reduction is governed by H2 and CH4. When the reaction temperature is higher than 800 °C and the M/H ratio is lower than unity, a heat supply is required to drive HTIR. The O/F ratio in LTIR and HTIR should be controlled below 2 to retard carbon formation and drive iron oxide reduction. - Highlights: • Direct partial oxidation of coke oven gas in blast furnace is analyzed thermodynamically. • A higher reaction temperature is conducive to CH4 conversion and syngas production. • At least 97.64% of Fe2O3 is converted. • The low-temperature indirect reduction is characterized by exothermic behavior. • The oxygen-to-fuel molar ratio in indirect reduction should be controlled below 2

  6. One-Pot Synthesis of Cu(II Complex with Partially Oxidized TTF Moieties

    Directory of Open Access Journals (Sweden)

    Hiroki Oshio

    2012-07-01

    Full Text Available The one-pot synthesis of a Cu(II complex with partially oxidized tetrathiafulvalene (TTF moieties in its capping MT-Hsae-TTF ligands, [CuII(MT-sae-TTF2] [CuICl2] was realized by the simultaneous occurrence of Cu(II complexation and CuIICl2 mediated oxidation of TTF moieties. The crystal structure was composed of one-dimensional columns formed by partially oxidized TTF moieties and thus the cation radical salt showed relatively high electrical conductivity. Tight binding band structure calculations indicated the existence of a Peierls gap due to the tetramerization of the TTF moieties in the one-dimensional stacking column at room temperature, which is consistent with the semiconducting behavior of this salt.

  7. Hydrogen production from partial oxidation of dimethyl ether using corona discharge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Ji-Jun; Liu, Chang-Jun [Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Zhang, Yue-ping [Department of Chemistry, Tianjin University, Tianjin 300072 (China)

    2007-06-15

    Dimethyl ether (DME), with its non-toxic character, high H/C ratio and high-energy volumetric density, is an ideal resource for hydrogen production. This work presents a hydrogen production from partial oxidation of DME using corona discharge plasma performed at ambient conditions. The partial oxidation can avoid the undesired carbon deposit existing in the decomposition of DME and a stable operation has been obtained. The carbon deposit is completely avoided when the O{sub 2}/DME ratio is 1.05. Partial oxidation can also greatly improve the conversion rate and energy efficiency. The optimal O{sub 2}/DME ratio is 1.38, with which the rate of H{sub 2} production is 1.33 times higher and the energy efficiency is 1.72 times higher than that of DME decomposition. The higher O{sub 2}/DME ratio results in complete oxidation and reduces the rate of H{sub 2} production. AC plasma is more efficient than the DC plasma and the optimum frequency is 2 kHz. The order of desired waveform is: sinusoid > sinusoid triangular > square > ramp. (author)

  8. Oxidation of SiC/BN/SiC Composites in Reduced Oxygen Partial Pressures

    Science.gov (United States)

    Opila, Elizabeth J.; Boyd, Meredith

    2010-01-01

    SiC fiber-reinforced SiC composites with a BN interphase are proposed for use as leading edge structures of hypersonic vehicles. The durability of these materials under hypersonic flight conditions is therefore of interest. Thermogravimetric analysis was used to characterize the oxidation kinetics of both the constituent fibers and composite coupons at four temperatures: 816, 1149, 1343, and 1538 C (1500, 2100, 2450, and 2800 F) and in oxygen partial pressures between 5% and 0.1% (balance argon) at 1 atm total pressure. One edge of the coupons was ground off so the effects of oxygen ingress into the composite could be monitored by post-test SEM and EDS. Additional characterization of the oxidation products was conducted by XPS and TOF-SIMS. Under most conditions, the BN oxidized rapidly, leading to the formation of borosilicate glass. Rapid initial oxidation followed by volatilization of boria lead to protective oxide formation and further oxidation was slow. At 1538C in 5% oxygen, both the fibers and coupons exhibited borosilicate glass formation and bubbling. At 1538C in 0.1% oxygen, active oxidation of both the fibers and the composites was observed leading to rapid SiC degradation. BN oxidation at 1538C in 0.1% oxygen was not significant.

  9. Effect of heat transfer on the oscillatory behavior in partial oxidation of methane over nickel catalyst

    Institute of Scientific and Technical Information of China (English)

    Xiubin Ren; Xiangyun Guo

    2011-01-01

    Monte Carlo method was applied to simulate the oscillatory behavior during partial oxidation of methane under non-isothermal condition.The simulation was performed to examine the influences of heat transfer constant and particle size on the kinetic oscillation.The oscillatory period and amplitude were observed to increase with the increase of heat transfer constant.The increase of catalyst particle size was found to result in short oscillatory period and more or less regular oscillations combined with the formation of oxide down to L =100.

  10. Partial oxidation of n- and i-pentane over promoted vanadium-phosphorus oxide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Zazhigalov, V.A.; Mikhajluk, B.D.; Komashko, G.A. [AN Ukrainskoj SSR, Kiev (Ukraine). Inst. Fizicheskoj Khimii

    1998-12-31

    It is known, that the cost of raw materials for catalytic oxidation processes is about 60% of the product price. Cheap initial compounds to produce variety of products and to replace olefins and aromatic hydrocarbons are paraffins. That is why catalytic systems which could be possibly rather efficient in selective oxidation of paraffin hydrocarbons are under very close investigation now. One of such processes in n-pentane oxidation. The obtained results on n-pentane oxidation over VPO catalysts were quite encouraging in respect of possible reach high selectivity and yield of phthalic anhydride. However, in our work it was shown that the main product of n-pentane oxidation in the presence of VPO catalytic system as well as VPMeO was maleic anhydride. Some later our results were confirmed in, where to grow the selectivity towards phthalic anhydride the Co-additive was introduced. On the basis of the proposal made before on the mechanism of paraffins conversion over the vanadyl pyrophosphate surface with their activation at the first and fourth carbon atoms, we assumed possible methylmaleic (citraconic) anhydride forming at n- and i-pentane oxidation. This assumption has been recently supported by both our and other researchers` experimental results. In it was also hypothized possible mechanistic features for phthalic anhydride forming from n-pentane. The present work deals with the results of n- and i-pentane oxidation over VPO catalysts promoted with Bi, Cs, Te, Zr. (orig.)

  11. Catalytic partial oxidation coupled with membrane purification to improve resource and energy efficiency in syngas production.

    Science.gov (United States)

    Iaquaniello, G; Salladini, A; Palo, E; Centi, G

    2015-02-01

    Catalytic partial oxidation coupled with membrane purification is a new process scheme to improve resource and energy efficiency in a well-established and large scale-process like syngas production. Experimentation in a semi industrial-scale unit (20 Nm(3)  h(-1) production) shows that a novel syngas production scheme based on a pre-reforming stage followed by a membrane for hydrogen separation, a catalytic partial oxidation step, and a further step of syngas purification by membrane allows the oxygen-to-carbon ratio to be decreased while maintaining levels of feed conversion. For a total feed conversion of 40 %, for example, the integrated novel architecture reduces oxygen consumption by over 50 %, with thus a corresponding improvement in resource efficiency and an improved energy efficiency and economics, these factors largely depending on the air separation stage used to produce pure oxygen. PMID:25571881

  12. Partial oxidation of methane to syngas in a mixed-conducting oxygen permeable membrane reactor

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Mixed-conducting oxygen permeable membranes represent a class of novel ceramic membranes, which exhibit mixed oxygen ionic and electronic conductivities. At high temperatures, oxygen can permeate through the membrane from the high to low oxygen pressure side under an oxygen concentration gradient. Theoretically, the permselectivity of oxygen is 100%. Recently, a novel mixed-conducting membrane--Ba0.5Sr0.5Co0.8Fe0.2O3-δ has been developed, which shows extremely high oxygen permeability and promising stability. Furthermore, the reactor made with such membranes was successfully applied to the partial oxidation of methane to syngas reaction using air as the oxygen source, which realized the coupling of the separation of oxygen from air and the partial oxidation of membrane reaction in one process. At 850℃, methane conversion >88%, CO selectivity >97% and oxygen permeation rate of about 7.8 mL/(cm2.min) were obtained.

  13. Effect of Ni Loading and Reaction Conditions on Partial Oxidation of Methane to Syngas

    Institute of Scientific and Technical Information of China (English)

    Haitao Wang; Zhenhua Li; Shuxun Tian

    2003-01-01

    The partial oxidation of methane to synthesis gas is studied in this paper over Ni/Al2O3 catalysts under atmospheric pressure. The effects of Ni loading on the activity and stability of catalysts with 5 mm α-Al2O3 and θ-Al2O3 pellets as supports were measured in a continuous fixed bed reactor. It is found that the optimum Ni loading is 10%. And the effect of reaction conditions on partial oxidation of methane is also studied. The methane conversion and CO selectivity increase with the increase of the reaction temperature and the space velocity on 10%Ni/α-Al2O3 catalysts. The best CH4/O2 mole ratio is 2 for CO selectivity, and the optimum space velocity is 5.4×105 h-1.

  14. Low-temperature sintering process for UO2 pellets in partially-oxidative atmosphere

    Institute of Scientific and Technical Information of China (English)

    YANG Xiao-dong; GAO Jia-cheng; WANG Yong; CHANG Xin

    2008-01-01

    Low-temperature sintering(LTS) experiments of UO2 pellets and their results were reported. Moreover, a routine process of LTS for UO2 pellets was primarily established. Being sintered at 1 400 ℃ for 3 h in a partially-oxidative atmosphere, the relative density of the pellet can be up to around 94%. Pellets with such a high density are of benefit for following-up reduction-sintering processes. Orthogonal test indicates that the importance of factors affecting the density decreases in the sequence of partial-oxidative sintering temperature and time, reduction-sintering time and temperature, and sintering atmosphere. It is found that it is helpful to introducing a small amount of water vapor into the sintering atmosphere during the latter stage. It is believed that it is the key factor to raise the O/U ratio of original powder in order to improve the properties of the low-temperature sintered pellets.

  15. Performance comparison between partial oxidation and methane steam for SOFC micro-CHP systems

    DEFF Research Database (Denmark)

    Liso, Vincenzo; Olesen, Anders Christian; Nielsen, Mads Pagh;

    2011-01-01

    and Partial Oxidation and recirculation of anode and cathode gas. The comparative analysis among the different configurations will lead us to conclude that maximum efficiency is achieved when cathode and anode gas recirculation are used along with steam methane reforming. Further Steam Methane Reforming...... process produces a higher electrical system efficiency compared to Partial oxidation reforming process. Efficiency is affected when running the system in part load mode mainly due to heat loss, additional natural gas supplied to the burner to satisfy the required heat demand inside the system, and ejector...... efficiency drop in the recirculation system. Due to high temperature of operation heat loss strongly affects the system efficiency especially at part load operation....

  16. Visualizing a Catalyst at Work during the Ignition of the Catalytic Partial Oxidation of Methane

    DEFF Research Database (Denmark)

    Kimmerle, Bertram; Grunwaldt, Jan-Dierk; Baiker, Alfons;

    2009-01-01

    We present a spatiotemporal operando X-ray absorption study of a highly dynamic process, the ignition of the noble metal catalyzed partial oxidation of methane. Evolvement and propagation of the platinum component's structural changes are investigated with a high-speed X-ray camera, which in comb...... in combination with temperature profiling by IR-thermography and catalytic activity measurements by online mass spectrometry gives insight into the first stages of the ignition of the reaction toward hydrogen and carbon monoxide.......We present a spatiotemporal operando X-ray absorption study of a highly dynamic process, the ignition of the noble metal catalyzed partial oxidation of methane. Evolvement and propagation of the platinum component's structural changes are investigated with a high-speed X-ray camera, which...

  17. Partial Oxidation of High-Boiling Hydrocarbon Mixtures in the Pilot Unit

    OpenAIRE

    Hanika, J. (Jiří); LEDERER, J.; Nečesaný, F.; Poslední, W.; Tukač, V.; Veselý, V

    2014-01-01

    The reason for this investigation into the partial oxidation (POX) of high-boiling hydrocarbons with oxygen in the presence of water vapour was to ensure increased demand on hydrogen, which is essential for the deeper hydrorefining of petroleum oils to ensure better quality of motor fuels. The tests demonstrated the good performance of the pilot plant unit and also the reproducibility of the experiment. The investigation detected a significant impact of water vapour on the selectivity of the ...

  18. Thermodynamic Study on the Catalytic Partial Oxidation of Methane to Syngas

    Institute of Scientific and Technical Information of China (English)

    XUJian; WEIWeisheng; 等

    2002-01-01

    The catalytic partial oxidation of methane to syngas (CO+H2) has been simulated thermodynamically with the advanced process simulator PRO/Ⅱ. The influences of temperature,pressure,CH4/O2 ratio and steam addition in feed gas on the conversion of CH4 selectively to syngas and heat duty required were investigated, and their effects on carbon formation were also discussed. The simulation results were in good agreement with the literature data taken from a spouted bed reactor.

  19. Effect of framework design on fracture resistance of zirconium oxide posterior fixed partial dentures

    OpenAIRE

    Hadi Salimi; Ramin Mosharraf; Omid Savabi

    2012-01-01

    Introduction: The effect of framework design modifications in all-ceramic systems is not fully understood. The aim of this investigation was to evaluate the effect of different framework designs on fracture resistance of zirconium oxide posterior fixed partial dentures (FPD). Materials and Methods: Thirty two posterior zirconia FPD cores were manufactured to replace a second premolar. The specimens were divided into four groups; I: 3 × 3 connector and standard design, II: 3 × 3 connector ...

  20. Partial oxidation of n-hexadecane through decomposition of hydrogen peroxide in supercritical water

    KAUST Repository

    Alshammari, Y.M.

    2015-01-01

    © 2014 The Institution of Chemical Engineers. This work reports the experimental analysis of partial oxidation of n-hexadecane under supercritical water conditions. A novel reactor flow system was developed which allows for total decomposition of hydrogen peroxide in a separate reactor followed partial oxidation of n-hexadecane in a gasification reactor instead of having both reactions in one reactor. The kinetics of hydrothermal decomposition of hydrogen peroxide was studied in order to confirm its full conversion into water and oxygen under the desired partial oxidation conditions, and the kinetic data were found in a good agreement with previously reported literature. The gas yield and gasification efficiency were investigated under different operating parameters. Furthermore, the profile of C-C/C=C ratio was studied which showed the favourable conditions for maximising yields of n-alkanes via hydrogenation of their corresponding 1-alkenes. Enhanced hydrogenation of 1-alkenes was observed at higher O/C ratios and higher residence times, shown by the increase in the C-C/C=C ratio to more than unity, while increasing the temperature has shown much less effect on the C-C/C=C ratio at the current experimental conditions. In addition, GC-MS analysis of liquid samples revealed the formation of heavy oxygenated compounds which may suggest a new addition reaction to account for their formation under the current experimental conditions. Results show new promising routes for hydrogen production with in situ hydrogenation of heavy hydrocarbons in a supercritical water reactor.

  1. Sulfur tolerance of selective partial oxidation of NO to NO2 in a plasma

    Energy Technology Data Exchange (ETDEWEB)

    Penetrante, B; Brusasco, R M; Merritt, B T; Vogtlin, G E

    1999-08-24

    Several catalytic aftertreatment technologies rely on the conversion of NO to NO2 to achieve efficient reduction of NOx and particulates in diesel exhaust. These technologies include the use of selective catalytic reduction of NOx with hydrocarbons, NOx adsorption, and continuously regenerated particulate trapping. These technologies require low sulfur fuel because the catalyst component that is active in converting NO to NO2 is also active in converting SO2 to SO3 . The SO3 leads t o increase in particulates and/or poison active sites on the catalyst. A non-thermal plasma can be used for the selective partial oxidation of NO to NO2 in the gas-phase under diesel engine exhaust conditions. This paper discusses how a non-thermal plasma can efficiently oxidize NO to NO2 without oxidizing SO2 to SO3 .

  2. Oxidation of polycyclic aromatic hydrocarbons using partially purified laccase from residual compost of agaricus bisporus

    Energy Technology Data Exchange (ETDEWEB)

    Mayolo-Deloisa, K. [Center for Biotechnology Research, Autonomous University of Morelos State, Cuernavaca, Morelos (Mexico); Center for Biotechnology-FEMSA, Monterrey Institute of Technology, Campus Monterrey, Monterrey (Mexico); Machin-Ramirez, C. [Center for Biotechnology Research, Autonomous University of Morelos State, Cuernavaca, Morelos (Mexico); Faculty of Chemical Sciences and Engineering, Autonomous University of Morelos State, Cuernavaca, Morelos (Mexico); Rito-Palomares, M. [Center for Biotechnology-FEMSA, Monterrey Institute of Technology, Campus Monterrey, Monterrey (Mexico); Trejo-Hernandez, M.R. [Center for Biotechnology Research, Autonomous University of Morelos State, Cuernavaca, Morelos (Mexico)

    2011-08-15

    Laccase partially purified from residual compost of Agaricus bisporus by an aqueous two-phase system (Lac ATPS) was used in degrading polycyclic aromatic hydrocarbons: fluorene (Flu), phenanthrene (Phe), anthracene (Ant), benzo[a]pyrene (BaP), and benzo[a]anthracene (BaA). The capacity of the enzyme to oxidize polyaromatic compounds was compared to that of the crude laccase extract (CE). After treatment of 72 h, Lac ATPS and CE were not capable of oxidizing Flu and Phe, while Ant, BaP, and BaA were oxidized, resulting in percentages of oxidation of 11.2 {+-} 1, 26 {+-} 2, and 11.7 {+-} 4 % with CE, respectively. When Lac ATPS was used, the following percentages of oxidation were obtained: 11.4 {+-} 3 % for Ant, 34 {+-} 0.1 % for BaP, and 13.6 {+-} 2 % for BaA. The results reported here demonstrate the potential application of Lac ATPS for the oxidation of polycyclic aromatic hydrocarbons. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Soft X-ray Spectroscopy Study of the Electronic Structure of Oxidized and Partially Oxidized Magnetite Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Gilbert, Benjamin; Katz, Jordan E.; Denlinger, Jonathan D.; Yin, Yadong; Falcone, Roger; Waychunas, Glenn A.

    2010-10-24

    The crystal structure of magnetite nanoparticles may be transformed to maghemite by complete oxidation, but under many relevant conditions the oxidation is partial, creating a mixed-valence material with structural and electronic properties that are poorly characterized. We used X-ray diffraction, Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy, and soft X-ray absorption and emission spectroscopy to characterize the products of oxidizing uncoated and oleic acid-coated magnetite nanoparticles in air. The oxidization of uncoated magnetite nanoparticles creates a material that is structurally and electronically indistinguishable from maghemite. By contrast, while oxidized oleic acid-coated nanoparticles are also structurally indistinguishable from maghemite, Fe L-edge spectroscopy revealed the presence of interior reduced iron sites even after a 2-year period. We used X-ray emission spectroscopy at the O K-edge to study the valence bands (VB) of the iron oxide nanoparticles, using resonant excitation to remove the contributions from oxygen atoms in the ligands and from low-energy excitations that obscured the VB edge. The bonding in all nanoparticles was typical of maghemite, with no detectable VB states introduced by the long-lived, reduced-iron sites in the oleic acid-coated sample. However, O K-edge absorption spectroscopy observed a 0.2 eV shift in the position of the lowest unoccupied states in the coated sample, indicating an increase in the semiconductor band gap relative to bulk stoichiometric maghemite that was also observed by optical absorption spectroscopy. The results show that the ferrous iron sites within ferric iron oxide nanoparticles coated by an organic ligand can persist under ambient conditions with no evidence of a distinct interior phase and can exert an effect on the global electronic and optical properties of the material. This phenomenon resembles the band gap enlargement caused by electron accumulation in the

  4. Partial Oxidation of n-Butane over a Sol-Gel Prepared Vanadium Phosphorous Oxide

    Directory of Open Access Journals (Sweden)

    Juan M. Salazar

    2013-01-01

    Full Text Available Vanadium phosphorous oxide (VPO is traditionally manufactured from solid vanadium oxides by synthesizing VOHPO4∙0.5H2O (the precursor followed by in situ activation to produce (VO2P2O7 (the active phase. This paper discusses an alternative synthesis method based on sol-gel techniques. Vanadium (V triisopropoxide oxide was reacted with ortho-phosphoric acid in an aprotic solvent. The products were dried at high pressure in an autoclave with a controlled excess of solvent. This procedure produced a gel of VOPO4 with interlayer entrapped molecules. The surface area of the obtained materials was between 50 and 120 m2/g. Alcohol produced by the alkoxide hydrolysis reduced the vanadium during the drying step, thus VOPO4 was converted to the precursor. This procedure yielded non-agglomerated platelets, which were dehydrated and evaluated in a butane-air mixture. Catalysts were significantly more selective than the traditionally prepared materials with similar intrinsic activity. It is suggested that the small crystallite size obtained increased their selectivity towards maleic anhydride.

  5. A novel technique for hydrogen production from hog-manure in supercritical partial oxidation (SCWPO)

    Energy Technology Data Exchange (ETDEWEB)

    Youssef, Emhemmed A.; Charpentier, Paul [Western Ontario Univ., London, ON (Canada). Dept. of Chemical and Biochemical Engineering; Nakhla, George [Western Ontario Univ., London, ON (Canada). Dept. of Chemical and Biochemical Engineering; Western Ontario Univ., London, ON (Canada). Dept. of Civil and Environmental Engineering; Elbeshbishy, Elsayed; Hafez, Hisham [Western Ontario Univ., London, ON (Canada). Dept. of Civil and Environmental Engineering

    2010-07-01

    In this study, the catalytic hydrogen production from hog manure using supercritical water partial oxidation was investigated in a batch reactor at a temperature of 500 C, and pressure of 28 MPa using several metallic catalysts. Hog manure was characterized by a total and soluble chemical oxygen demand (TCOD, SCOD) of 57000 and 28000 mg/L, total and volatile suspended solids (TSS, VSS) of 25000, 19000, and ammonia of 2400 mg/L, respectively. The order of H{sub 2} production was the following: Pd/AC > Ru/Al{sub 2}O{sub 3} > Ru/AC > AC > NaOH. The order of COD reduction efficiency was as follows: NaOH > Ru/AC > AC > Ru/Al{sub 2}O{sub 3} > Pd/AC. The behaviour of the volatile fatty acids (VFA's), ethanol, methanol, ammonia, H{sub 2}S, and Sulfate was investigated experimentally and discussed. A 35 % reduction in the H{sub 2} and CH{sub 4} yields was observed in the sequential gasification partial oxidation (oxidant at an 80 % of theoretical requirement) experiments compared to the gasification experiments (catalyst only). Moreover, this reduction in gas yields was coincided with a 45 % reduction in the liquid effluent chemical oxygen demand (COD), 60 % reduction of the ammonia concentration in the liquid effluent, and 20 % reduction in the H{sub 2}S concentration in the effluent gas. (orig.)

  6. Hemicellulose hydrolysis catalysed by solid acids

    NARCIS (Netherlands)

    P.D.. Carà; M. Pagliaro; A. Elmekawy; D.R. Brown; P. Verschuren; N.R. Shiju; G. Rothenberg

    2013-01-01

    Depolymerising hemicellulose into platform sugar molecules is a key step in developing the concept of an integrated biorefinery. This reaction is traditionally catalysed by either enzymes or homogeneous mineral acids. We compared various solid catalysts for hemicellulose hydrolysis, running reaction

  7. Numerical study on soot removal in partial oxidation of methane to syngas reactors

    Institute of Scientific and Technical Information of China (English)

    Weisheng; Wei; Tao; Zhang; Jian; Xu; Wei; Du

    2014-01-01

    The serious carbon deposition existing in catalytic partial oxidation of methane(CPOM) to syngas process is one of the key problems that impede its industrialization. In this study, 3-dimensional unsteady numerical simulations of the soot formation and oxidation in oxidation section in a heat coupling reactor were carried out by computational fluid dynamics(CFD) approach incorporating the Moss-Brookes model for soot formation. The model has been validated and proven to be in good agreement with experiment results. Effects of nozzle type,nozzle convergence angle, channel spacing, number of channels, radius/height ratio, oxygen/carbon ratio, preheat temperature and additional introduction of steam on the soot formation were simulated. Results show that the soot formation in oxidation section of the heat coupling reactor depends on both nozzle structures and operation conditions, and the soot concentration can be greatly reduced by optimization with the maximum mass fraction of soot inside the oxidation reactor from 2.28% to 0.0501%, and so that the soot mass fraction at the exit reduces from0.74% to 0.03%.

  8. On the sensitivity to partial pressure of oxygen of the mobility in cadmium oxide

    Science.gov (United States)

    Grado-Caffaro, M. A.; Grado-Caffaro, M.

    2015-11-01

    The partial pressure of oxygen during the deposition process of cadmium oxide is a crucial quantity whose influence on the electrical and optical properties of this material is really very significant (consider, for example, the experimental technique known as activated reactive evaporation). In fact, this paper is a theoretical formulation to evaluate the sensitivity changes of the aforementioned pressure of the electron drift-mobility and velocity in CdO. Indeed, as we will see later, given that the electron relaxation time depends upon the oxygen partial pressure, then the electron drift-mobility, mean free path and velocity also depend on this pressure. Relevant calculations involving the above physical quantities are carried out.

  9. Production of hydrogen via partial oxidation of methanol over Au/TiO{sub 2} catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Feg-Wen; Yu, Hsin-Yin; Selva Roselin, L.; Yang, Hsien-Chang [Department of Chemical and Materials Engineering, National Central University, Chungli 32001 (Taiwan)

    2005-08-18

    Selective production of hydrogen by partial oxidation of methanol (CH{sub 3}OH+(1/2)O{sub 2}->2H{sub 2}+CO{sub 2}) over Au/TiO{sub 2} catalysts, prepared by a deposition-precipitation method, was studied. The catalysts were characterized by XRD, TEM, and XPS analyses. TEM observations show that the Au/TiO{sub 2} catalysts exhibit hemispherical gold particles, which are strongly attached to the metal oxide support at their flat planes. The size of the gold particles decreases from 3.5 to 1.9nm during preparation of the catalysts with the rise in pH from 6 to 9 and increases from 2.9 to 4.3nm with the rise in calcination temperature up to 673K. XPS analyses demonstrate that in uncalcined catalysts gold existed in three different states: i.e., metallic gold (Au{sup 0}), non-metallic gold (Au{sup {delta}}{sup +}) and Au{sub 2}O{sub 3}, and in catalysts calcined at 573K only in metallic state. The catalytic activity is strongly dependent on the gold particle size. The catalyst precipitated at pH 8 and uncalcined catalysts show the highest activity for hydrogen generation. The partial pressure of oxygen plays an important role in determining the product distribution. There is no carbon monoxide detected when the O{sub 2}/CH{sub 3}OH molar ratio in the feed is 0.3. Both hydrogen selectivity and methanol conversion increase with increasing the reaction temperature. The reaction pathway is suggested to consist of consecutive methanol combustion, partial oxidation and steam reforming.

  10. Partially oxidized atomic cobalt layers for carbon dioxide electroreduction to liquid fuel

    Science.gov (United States)

    Gao, Shan; Lin, Yue; Jiao, Xingchen; Sun, Yongfu; Luo, Qiquan; Zhang, Wenhua; Li, Dianqi; Yang, Jinlong; Xie, Yi

    2016-01-01

    Electroreduction of CO2 into useful fuels, especially if driven by renewable energy, represents a potentially ‘clean’ strategy for replacing fossil feedstocks and dealing with increasing CO2 emissions and their adverse effects on climate. The critical bottleneck lies in activating CO2 into the CO2•- radical anion or other intermediates that can be converted further, as the activation usually requires impractically high overpotentials. Recently, electrocatalysts based on oxide-derived metal nanostructures have been shown to enable CO2 reduction at low overpotentials. However, it remains unclear how the electrocatalytic activity of these metals is influenced by their native oxides, mainly because microstructural features such as interfaces and defects influence CO2 reduction activity yet are difficult to control. To evaluate the role of the two different catalytic sites, here we fabricate two kinds of four-atom-thick layers: pure cobalt metal, and co-existing domains of cobalt metal and cobalt oxide. Cobalt mainly produces formate (HCOO-) during CO2 electroreduction; we find that surface cobalt atoms of the atomically thin layers have higher intrinsic activity and selectivity towards formate production, at lower overpotentials, than do surface cobalt atoms on bulk samples. Partial oxidation of the atomic layers further increases their intrinsic activity, allowing us to realize stable current densities of about 10 milliamperes per square centimetre over 40 hours, with approximately 90 per cent formate selectivity at an overpotential of only 0.24 volts, which outperforms previously reported metal or metal oxide electrodes evaluated under comparable conditions. The correct morphology and oxidation state can thus transform a material from one considered nearly non-catalytic for the CO2 electroreduction reaction into an active catalyst. These findings point to new opportunities for manipulating and improving the CO2 electroreduction properties of metal systems

  11. Hydrogen or Soot?: Partial Oxidation of High-boiling Hydrocarbon Wastes

    OpenAIRE

    LEDERER, J.; Hanika, J. (Jiří); Nečesaný, F.; Poslední, W.; Tukač, V.; Veselý, V

    2015-01-01

    This paper is focused on researching the influence of process parameters of partial oxidation, such as quality of hydrocarbon raw materials that differ in their stock properties (especially boiling point and viscosity) on the composition of output gas (selectivity of the process), and also on the formation extent of soot which could be used as an excellent and valued sorbent CHEZACARB® and/or filler in the rubber industry, e.g. for automotive tires. The effects of steam flow rate and the o...

  12. Hydrogen or Soot ?: Partial Oxidation of High-Boiling Hydrocarbon Wastes

    OpenAIRE

    LEDERER, J.

    2014-01-01

    This paper is focussed to research of the influence of process parameters of partial oxidation like quality of hydrocarbon raw materials, which differed in their stock properties (especially the boiling point and viscosity), on the composition of output gas (selectivity of the process) and also on the formation extent of soot which can be used as an excellent and valued sorbent CHEZACARB(™) and/or filler in rubber industry, e.g. for automotive tires. The effects of steam flow rate and oxygen...

  13. Lanthanum Modified Ni/γ-Al2O3 Catalysts for Partial Oxidation of Methane

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    La modified Ni/γ-Al2O3 catalysts prepared by co-precipitation method using NaOH-Na2CO3 as a precipitator show high activity and selectivity for the partial oxidation of methane (POM). Meanwhile, the addition of La is beneficial for the formation of an active component and stability of support. We investigated some factors including calcining temperature, nickel content, and space velocity, which turned out to have a strong influence on catalytic activity and selectivity. By XRD and TPR, it is concluded that Ni0 reduced from amorphous NiAl2O4 is the major active component for POM.

  14. Yttria promoted metallic nickel catalysts for the partial oxidation of methane to synthesis gas

    Institute of Scientific and Technical Information of China (English)

    Yaquan Wang; Xuebin Hong; Bingbing Li; Wenju Wang; Dalin Wang

    2008-01-01

    A metallic Ni catalyst was prepared with nickel sponge, followed by acid treatment. It was further promoted with yttria by an impregnation method. The catalysts were characterized by SEM, BET, XRD, TPR, XPS, etc., and studied in the partial oxidation of methane to syngas. The characterization results showed that the yttria promoted metallic Ni catalysts had high specific surface area and more NiO. The reaction results showed that the yttria promoter increased the CH4 conversion and the selectivity for H2 and CO.

  15. CO2 separation by calcium looping from full and partial fuel oxidation processes

    OpenAIRE

    Sivalingam, Senthoorselvan

    2013-01-01

    This thesis work deals with the research and development of Calcium Looping(CaL) process for CO2 separation from full and partial fuel oxidation based power generation systems. CaL process involves separation of CO2 at high temperatures (600-700°C) by calcium sorbents (CaO). CO2 reacts with CaO in a carbonation process and produces CaCO3. In a subsequent thermal regeneration (>850°C) called calcination, the CO2 is released from CaCO3. Moreover, the CaL is realised in industrial scale with dua...

  16. Methyl Chloride from Direct Methane Partial Oxidation: A High-Temperature Shilov-Like Catalytic System

    Energy Technology Data Exchange (ETDEWEB)

    Yongchun Tang; John (Qisheng) Ma

    2012-03-23

    The intention of this study is to demonstrate and evaluate the scientific and economic feasibility of using special solvents to improve the thermal stability of Pt-catalyst in the Shilov system, such that a high reaction temperature could be achieved. The higher conversion rate (near 100%) of methyl chloride from partial oxidation of methane under the high temperature ({approx} 200 C) without significant Pt0 precipitation has been achieved. High concentration of the Cl- ion has been identified as the key for the stabilization of the Pt-catalysts. H/D exchange measurements indicated that the over oxidation will occur at the elevated temperature, developments of the effective product separation processes will be necessary in order to rationalize the industry-visible CH4 to CH3Cl conversion.

  17. Partial oxidation of landfill leachate in supercritical water: Optimization by response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Yanmeng; Wang, Shuzhong; Xu, Haidong; Guo, Yang; Tang, Xingying

    2015-09-15

    Highlights: • Partial oxidation of landfill leachate in supercritical water was investigated. • The process was optimized by Box–Behnken design and response surface methodology. • GY{sub H2}, TRE and CR could exhibit up to 14.32 mmol·gTOC{sup −1}, 82.54% and 94.56%. • Small amounts of oxidant can decrease the generation of tar and char. - Abstract: To achieve the maximum H{sub 2} yield (GY{sub H2}), TOC removal rate (TRE) and carbon recovery rate (CR), response surface methodology was applied to optimize the process parameters for supercritical water partial oxidation (SWPO) of landfill leachate in a batch reactor. Quadratic polynomial models for GY{sub H2}, CR and TRE were established with Box–Behnken design. GY{sub H2}, CR and TRE reached up to 14.32 mmol·gTOC{sup −1}, 82.54% and 94.56% under optimum conditions, respectively. TRE was invariably above 91.87%. In contrast, TC removal rate (TR) only changed from 8.76% to 32.98%. Furthermore, carbonate and bicarbonate were the most abundant carbonaceous substances in product, whereas CO{sub 2} and H{sub 2} were the most abundant gaseous products. As a product of nitrogen-containing organics, NH{sub 3} has an important effect on gas composition. The carbon balance cannot be reached duo to the formation of tar and char. CR increased with the increase of temperature and oxidation coefficient.

  18. Green chemicals from pulp production black liquor by partial wet oxidation.

    Science.gov (United States)

    Muddassar, Hassan Raja; Melin, Kristian; de Villalba Kokkonen, Daniela; Riera, Gerard Viader; Golam, Sarwar; Koskinen, Jukka

    2015-11-01

    To reduce greenhouse gas emissions, more sustainable sources of energy, fuel and chemicals are needed. Biomass side streams such as black liquor, which is a by-product of pulp production, has the potential to be used for this purpose. The aim of the study was the production of carboxylic acids, such as lactic acid, formic acid and acetic acid, from kraft and non-wood black liquor. The processes studied were partial wet oxidation (PWO) and catalytic partial wet oxidation (CPWO). The results show that the yield of carboxylic acid is higher when treated by PWO than the results from CPWO at temperatures of 170 °C and 230 °C. The results shows that the PWO process can increase the yield of carboxylic acids and hydroxy acids in black liquor, reduce lignin content and decrease pH, which makes further separation of the acids more favourable. The hydroxy acids are valuable raw materials for biopolymers, and acetic acid and formic acid are commonly used chemicals conventionally produced from fossil feedstock. PMID:26377325

  19. Behaviour of heavy metals in the partial oxidation of heavy fuel oil

    Energy Technology Data Exchange (ETDEWEB)

    Brueggemann, P.; Baitalow, F.; Seifert, P.; Meyer, B. [TU Bergakademie Freiberg, Department of Energy Process Engineering and Chemical Engineering, Reiche Zeche, Fuchsmuehlenweg 9, 09596 Freiberg (Germany); Schlichting, H. [Lurgi GmbH, Frankfurt (Germany)

    2010-02-15

    The behaviour of heavy metals in the partial oxidation of heavy fuel oils under a pressure of up to 100 bar (10 MPa) has been investigated. The tests were carried out in a 5 MW HP POX (High Pressure Partial Oxidation) test plant, that is operated by the IEC (Department of Energy Process Engineering and Chemical Engineering, TU Bergakademie Freiberg) in cooperation with Lurgi GmbH. In several test campaigns preheated oil with a viscosity of up to 300 cSt (= 300 mm{sup 2}/s) at the burner inlet has been gasified. The heavy metals nickel Ni, iron Fe and vanadium V occur in heavy residual oils in considerable concentration and may seriously impact the gasification itself and the synthesis gas conditioning and usage. While iron is largely recovered in the gasification residue, the recovery rates of nickel and vanadium depend on the process conditions. Volatile nickel compounds were detected in the raw synthesis gas. It was found that an incomplete carbon conversion enables the capture of nickel Ni and vanadium V in the solid residue phase and can thus mitigate the problem of volatile metal compounds in the raw synthesis gas. (author)

  20. Interaction of Zr with oxidized and partially reduced ceria thin films

    Science.gov (United States)

    Wang, Weijia; Hu, Shanwei; Han, Yong; Pan, Xiao; Xu, Qian; Zhu, Junfa

    2016-11-01

    The growth and electronic properties of Zr on the ceria thin films were studied by X-ray photoelectron spectroscopy, low energy electron diffraction (LEED), scanning tunneling microscopy (STM) and work function measurements. Metallic zirconium was vapor-deposited on the well-ordered fully oxidized CeO2(111) and partially reduced CeO2-x(111) (0 < x < 0.5) thin films, which were epitaxially grown on a Ru(0001) substrate, under ultrahigh vacuum (UHV) conditions. The results show that the deposition of Zr on both ceria surfaces leads to electron transfer from Zr to ceria, accompanied by partial reduction of Ce from Ce4 + to Ce3 + states and oxidation of metallic Zr to Zr4 +. Moreover, with increasing the Zr coverage, the reduction degree of ceria films increases and eventually only Ce3 + is observed at a high coverage of Zr. The STM results suggest that Zr grows two-dimensionally (2D) on the CeO2(111) thin film at low coverages due to the strong interaction between Zr and CeO2(111).

  1. Effects of Techniques of Implanting Nitrogen into Buried Oxide on the Characteristics of Partially Depleted SOI PMOSFET

    Institute of Scientific and Technical Information of China (English)

    ZHENG Zhong-Shan; LIU Zhong-Li; ZHANG Guo-Qiang; LI Ning; FAN Kai; ZHANG En-Xia; YI Wan-Bing; CHEN Meng; WANG Xi

    2005-01-01

    @@ Effects of techniques of implanting nitrogen into buried oxide on the characteristics of the partially depleted silicon-on-insulator (SOI) p-channel metal-oxide-semiconductor field-effect transistors (PMOSFETs) have beenstudied with three different nitrogen implantation doses, 8 × 1015, 2 × 1016, and 1 × 1017 cm-2.

  2. Sulfur recovery from low H{sub 2}S content acid gas using catalytic partial oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Clark, P.D.; Dowling, N.I.; Huang, M.

    2010-01-15

    The poster presentation discussed a new strategy for recovering sulfur from low hydrogen-sulphide-content acid gas using catalytic partial oxidation. In a new technology for dealing with BTX-contaminated lean acid gas, a catalytic reactor replaces the burner-furnace stage to achieve BTX conversion greater than 95 percent and control the hydrogen sulfide/sulfur dioxide ratio. The product gas is then sent to the Claus catalytic converters. The best catalysts for this process are alumina-supported Co-Mo and y-alumina. This process was compared with SELECTOX, another process that deals with poor acid gas with BTX conversion better than 95 percent. Catalytic oxidation can deal with a higher BTX feed content than SELECTOX, but the running temperature is higher. Both processes produce acceptable sulfur quality. To improve this process, the quality of the sulfur produced and the lifetime of the catalyst need to be increased, and an economic way to increase the heat to reach the running temperature needs to be found. The partial oxidation (POX) of CH{sub 4} solves both of these problems. The catalytic POX of acid gas is combined with the POX of fuel gas in the pre-heating zone. This process has the advantage that the burner-furnace stage of the Claus process can be replaced by a stream containing H{sub 2}S/SO{sub 2}=2; the reaction is performed at its adiabatic temperature requiring only a small amount of fuel gas; the presence of H{sub 2} and CO produced by the POX of fuel gas improves the quality of sulfur; the catalyst remains active for about 30 hours; and the process can tolerate high BTX content. 6 tabs., 2 figs.

  3. Partial catalytic oxidation of CH{sub 4} to synthesis gas for power generation - Final report

    Energy Technology Data Exchange (ETDEWEB)

    Mantzaras, I.; Schneider, A.

    2006-03-15

    The partial oxidation of methane to synthesis gas over rhodium catalysts has been investigated experimentally and numerically in the pressure range of 4 to 10 bar. The methane/oxidizer feed has been diluted with large amounts of H{sub 2}O and CO{sub 2} (up to 70% vol.) in order to simulate new power generation cycles with large exhaust gas recycle. Experiments were carried out in an optically accessible channel-flow reactor that facilitated laser-based in situ measurements, and also in a subscale gas-turbine catalytic reactor. Full-elliptic steady and transient two-dimensional numerical codes were used, which included elementary hetero-/homogeneous chemical reaction schemes. The following are the key conclusions: a) Heterogeneous (catalytic) and homogeneous (gas-phase) schemes have been validated for the partial catalytic oxidation of methane with large exhaust gas recycle. b) The impact of added H{sub 2}O and CO{sub 2} has been elucidated. The added H{sub 2}O increased the methane conversion and hydrogen selectivity, while it decreased the CO selectivity. The chemical impact of CO{sub 2} (dry reforming) was minimal. c) The numerical model reproduced the measured catalytic ignition times. It was further shown that the chemical impact of H{sub 2}O and CO{sub 2} on the catalytic ignition delay times was minimal. d) The noble metal dispersion increased with different support materials, in the order Rh/{alpha}-Al{sub 2}O{sub 3}, Rh/ZrO{sub 2}, and Rh/Ce-ZrO{sub 2}. An evident relationship was established between the noble metal dispersion and the catalytic behavior. (authors)

  4. Hydrogen production by ethanol partial oxidation over nano-iron oxide catalysts produced by chemical vapour synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Wael Ahmed Abou Taleb Sayed

    2011-01-13

    This work presents the experimental results of the synthesis of unsupported and supported SiC iron oxide nanoparticles and their catalytic activity towards ethanol partial oxidation. For comparison, further unsupported iron oxide phases were investigated towards the ethanol partial oxidation. These {gamma}-Fe{sub 2}O{sub 3} and {alpha}/{gamma}-Fe{sub 2}O{sub 3} phase catalysts were prepared by the CVS method using Fe(CO){sub 5} as precursor, supplied by another author. The {alpha}-Fe{sub 2}O{sub 3} and SiC nanoparticles were prepared by the CVS method using a home made hot wall reactor technique at atmospheric pressure. Ferrocene and tetramethylsilane were used as precursor for the production process. Process parameters of precursor evaporation temperature, precursor concentration, gas mixture velocity and gas mixture dilution were investigated and optimised to produce particle sizes in a range of 10 nm. For Fe{sub 2}O{sub 3}/SiC catalyst series production, a new hot wall reactor setup was used. The particles were produced by simultaneous thermal decomposition of ferrocene and tetramethylsilane in one reactor from both sides. The production parameters of inlet tube distance inside the reactor, precursor evaporation temperature and carrier gas flow were investigated to produce a series of samples with different iron oxide content. The prepared catalysts composition, physical and chemical properties were characterized by XRD, EDX, SEM, BET surface area, FTIR, XPS and dynamic light scattering (DLS) techniques. The catalytic activity for the ethanol gas-phase oxidation was investigated in a temperature range from 260 C to 290 C. The product distributions obtained over all catalysts were analysed with mass spectrometry analysis tool. The activity of bulk Fe{sub 2}O{sub 3} and SiC nanoparticles was compared with prepared nano-iron oxide phase catalysts. The reaction parameters, such as reaction temperature and O{sub 2}/ethanol ratio were investigated. The catalysts

  5. Partial oxidation of sewage sludge briquettes in a updraft fixed bed.

    Science.gov (United States)

    Kim, Minsu; Lee, Yongwoon; Park, Jinje; Ryu, Chankook; Ohm, Tae-In

    2016-03-01

    The fixed bed reaction of sewage sludge briquettes was investigated to evaluate the potential applications to gasification, combustion, or production of biochar as soil ameliorator. The reaction had two distinctive stages: ignition propagation and char oxidation. The ignition front of the sludge briquettes propagated at a lower speed, which significantly increased the stoichiometric ratio of overall combustion reaction and peak temperatures. The ignition front also had irregular shapes due to the channeling effects. During the char oxidation stage, the sludge ash agglomerated because of the slow reaction rate and increased CO2 formation. Because of low energy content in the product gas, the large briquettes were not favorable for syngas production. In addition, the low burning rates and ash agglomeration could cause problems in the operation of a grate-type furnace for combustion. However, the char accumulated above the ignition front had similar properties with that from pyrolysis under inert atmosphere. Therefore, the fixed bed reaction under partial oxidation conditions can be applied to produce biochar as soil ameliorator from the sludge briquettes without external heat supply. PMID:26860426

  6. Laser ablated plasma plume diagnostics of cerium oxide: effect of oxygen partial pressure

    International Nuclear Information System (INIS)

    This paper describes the spatial and temporal investigation of laser ablated plasma plume of cerium oxide target using Langmuir probe to measure the plasma parameters. Cerium oxide target was ablated using a KrF (λ ∼ 248 nm) gas laser at an energy of 300 mJ per pulse. Experimental studies confirmed that oxygen partial pressure of 2 x 10-2 mbar is sufficient enough to get good quality films of cerium oxide. At this pressure, plume was diagnosed for their spatial and temporal behaviour. The tungsten probe tip was inserted along the length of the plasma to collect the ions and electrons effectively. A thin probe tip (about 0.4 mm diameter) was used to avoid plasma perturbation during measurements. A variable voltage was applied to the tip and corresponding current due to electrons and ions was collected. Spatial distribution was investigated at a regular interval of 15 mm from the target up maximum distance 45 mm and the temporal behaviour was recorded in the range of 0 to 50 μS with an interval of 0.5 μS. The ion and average electron density are found to be maximum at 30 mm from the target position and the plasma current of ceria is found to be maximum at 22 μS. (author)

  7. Catalytic partial oxidation of methane over porous silica supported VO{sub x} catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Pirovano, C.; Schoenborn, E.; Kalevaru, V.N.; Wohlrab, S.; Luecke, B.; Martin, A. [University Rostock e.V., Rostock (Germany). Leibniz Inst. for Catalysis

    2011-07-01

    High surface area mesoporous siliceous MCM-41 and SBA-15 materials have been used as supports to disperse vanadium oxide species using wet impregnation and incipient wetness impregnation methods. These materials were used as catalysts for the partial oxidation of methane (POM) to formaldehyde. The physico-chemical properties of the solids were studied by means of BET, DR-UV/Vis spectroscopy, Py-FTIR and TEM. The influence of support and the preparation method on the dispersion of VOx is also investigated. The catalytic properties of the catalysts were examined in a fixed bed stainless steel reactor at 923 K. So far a maximum production of formaldehyde can be detected on SBA-15 supported VOx-catalysts prepared by incipient wetness impregnation. On this V/SBA-15 material a covalent attachment of catalytic active molecular vanadium species dominates, which in turn leads to a lower activation temperature and thereby reduced over-oxidation. From the best case, the space time yield of HCHO could be reached close to 775 g{sub HCHO} Kg{sub cat}{sup -1} h{sup -1}. (orig.)

  8. Isothermal oxidation of physical vapor deposited partially stabilized zirconia thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Sohn, Y.H.; Biederman, R.R.; Sisson, R.D. Jr. (Worcester Polytechnic Inst., MA (United States). Materials Engineering Labs.)

    1994-02-01

    Thermal barrier coatings (TBCs), consisting of physical vapor deposited (PVD) partially stabilized zirconia (PSZ, 8 wt.% Y[sub 2]O[sub 3]) and a diffusion aluminide bond coat, were characterized as a function of time after oxidative isothermal heat treatment at 1,373 K in air. The experimental characterizations was conducted by X-ray diffraction analysis and scanning electron microscopy (SEM) with energy-dispersive spectroscopy. During cooling to room temperature, spallation of the PSZ ceramic coatings occurred after 200 and 350 h of isothermal heat treatment. This failure was always sudden and violent, with the TBC popping from the substrate. The monoclinic phase of zirconia was first observed on the bottom surface of the PVD PSZ after 200 h of isothermal heat treatment. The failure of TBCs occurred either in the bond coat oxidation products of [alpha]Al[sub 2]O[sub 3] and rutile TiO[sub 2] or at the interface between the oxidation products and the diffusion aluminide bond coat or the PSZ coating.

  9. Isothermal oxidation of physical vapor deposited partially stabilized zirconia thermal barrier coatings

    Science.gov (United States)

    Sohn, Y. H.; Biederman, R. R.; Sisson, R. D.

    1994-02-01

    Thermal barrier coatings (TBCs), consisting of physical vapor deposited (PVD) partially stabilized zirconia (PSZ, 8 wt.%Y2O3) and a diffusion aluminide bond coat, were characterized as a function of time after oxidative isothermal heat treatment at 1373 K in air. The experimental characterizations was conducted by X-ray diffraction analysis and scanning electron microscopy (SEM) with energy-dispersive spectroscopy. During cooling to room temperature, spallation of the PSZ ceramic coatings occurred after 200 and 350 h of isothermal heat treatment. This failure was always sudden and violent, with the TBC popping from the substrate. The monoclinic phase of zirconia was first observed on the bottom surface of the PVD PSZ after 200 h of isothermal heat treatment. The failure of TBCs occurred either in the bond coat oxidation products of αAl2O3 and rutile TiO2 or at the interface between the oxidation products and the diffusion aluminide bond coat or the PSZ coating.

  10. Partial Oxidation of Butane to Syngas over Nickel SupportedCatalysts Modified by Alkali Metal Oxide and Rare-Earth Metal Oxide

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The partial oxidation of butane (POB) to syngas over nickel supported catalysts was first investigated with a flow-reactor, TG and UVRRS. The NiO/g-Al2O3 is the most suitable for the POB among NiO/g-Al2O3, NiO/MgO and NiO/SiO2. And the reaction performance of the NiO/g-Al2O3 shows little difference from those of the nickel supported catalysts modified by alkali metal oxide and rare-earth metal oxide. However, modification with Li2O and La2O3 can suppress carbon-deposition of the NiO/g-Al2O3, which contains graphite-like species during the POB reaction.

  11. Hydrogen production by partial oxidation of methanol over gold supported on Fe2O3.

    Science.gov (United States)

    Roselin, L Selva; Liao, Li-Mei; Ou, You-Chen; Chang, Feg-Wen

    2014-09-01

    Partial oxidation of methanol (POM) to produce hydrogen was investigated over Au/Fe2O3 catalysts. The catalysts were prepared by inverse co-precipitation method. The influence of catalyst synthesis parameters such as precipitant, gold loading, calcination temperature and reaction parameter such as reaction temperature on POM reaction to produce hydrogen were investigated. The catalysts have been characterized by means of TGA, BET, XRD, TEM, SEM-EDS and XPS analyses. TGA and DTGA profiles clearly indicate that minimum decomposition temperature required to obtain Fe2O3 in Au/Fe2O3 catalysts is 660 K. SEM-EDS analysis confirms that Au and Fe in Au/Fe2O3 are homogeneously distributed over the agglomerate. A detailed microstuctural characterization of Au/Fe2O3 sample by XRD, TEM and XPS analyses has shown that nanometer sized gold particles with oxidized gold species is in predominant amount in the uncalcined catalysts sample. The mean particle size and metallic state of gold particles increase with increasing calcination temperature. A highly active Au/Fe2O3 catalyst is obtained by using Na2CO3 as precipitant with lower gold loading and calcination at 673 K. The catalytic behavior of the Au/Fe2O3 catalyst is related not only to the gold but also to the chemical state of the support. The effect of reaction temperature on the catalytic performance of the Au/Fe2O3 catalysts was studied in the temperature range of 423 to 523 K. Oxygen conversion was complete through out the examined temperature range. Methanol conversion increased with rise in temperature and attains 100% at 503 K; Hydrogen selectivity increased with rise in reaction temperature up to 523 K and then dropped off. The overall reactions involved are methanol combustion, partial oxidation, steam reforming and decomposition. CO produced by methanol decomposition and/or by reverse water gas shift is subsequently transformed into CO2 and H2 by the water gas shift and/or CO oxidation. PMID:25924393

  12. Influence of Supports on Catalytic Performance and Carbon Deposition of Palladium Catalyst for Methane Partial Oxidation

    Institute of Scientific and Technical Information of China (English)

    Shi Fangli; Shen Meiqing; Fei Yanan; Wang Jun; Weng Duan

    2007-01-01

    The catalytic performance of methane partial oxidation was investigated on Pd/CeO2-ZrO2 and Pd/α-Al2O3 catalysts. The catalysts were characterized by XRD, Raman spectra, and TG-DTA techniques. The results show that CeO2-ZrO2 support is more advantageous for the catalytic activity and stability of catalysts compared to α-Al2O3. TG-DTA and Raman spectra results indicated that carbon deposited on the catalysts was in the form of graphite, which is the main reason for the deactivation of catalysts after a 24-hour reaction. Moreover, CeO2-ZrO2 had positive effect on inhibiting carbon deposition.

  13. Partial oxidation of methane to syngas catalyzed by a nickel nanowire catalyst

    Institute of Scientific and Technical Information of China (English)

    Xuebin Hong; Yaquan Wang

    2009-01-01

    A nickel nanowire catalyst was prepared by a hard template method,and characterized by transmission electron microscopy (TEM),N2 physical adsorption,X-ray photoelectron spectrometry (XPS),X-ray diffraction (XRD) and H2 temperature-programmed reduction (H2-TPR).The catalytic properties of the nanowire catalyst in the partial oxidation of methane to syngas were compared with a metallic Ni catalyst which was prepared with nickel sponge.The characterization results showed that the nickel nanowire catalyst had high specific surface area and there was more NiO phase in the nickel nanowire catalyst than in the metallic Ni catalyst.The reaction results showed that the nickel nanowire catalyst had high CH4 conversion and selectivities for H2 and CO under low space velocity.

  14. Adiabatic Gasification and Pyrolysis of Coffee Husk Using Air-Steam for Partial Oxidation

    Directory of Open Access Journals (Sweden)

    Catalina Rodriguez

    2011-01-01

    Full Text Available Colombian coffee industry produces about 0.6 million tons of husk (CH per year which could serve as feedstock for thermal gasification to produce gaseous and liquid fuels. The current paper deals with: (i CH adiabatic gasification modeling using air-steam blends for partial oxidation and (ii experimental thermogravimetric analysis to determine the CH activation energy (E. The Chemical Equilibrium with Applications Program (CEA, developed by NASA, was used to estimate the effect of equivalence ratio (ER and steam to fuel ratio (S : F on equilibrium temperature and gas composition of ~150 species. Also, an atom balance model was developed for comparison purposes. The results showed that increased ER and (S : F ratios produce mixtures that are rich in H2 and CO2 but poor in CO. The value for the activation energy was estimated to be 221 kJ/kmol.

  15. Investigation on the Performance of Supported Molybdenum Carbide for the Partial Oxidation of Methane

    Institute of Scientific and Technical Information of China (English)

    Quanli Zhu; Jian Yang; Jiaxin Wang; Shengfu Ji; Hanqing Wang

    2003-01-01

    The performance of supported and unsupported molybdenum carbide for the partial oxida-tion of methane (POM) to syngas was investigated. An evaluation of the catalysts indicates that bulkmolybdenum carbide has a higher methane conversion during the initial stage but a lower selectivity toCO and H2/CO ratio in the products. The rapid deactivation of the catalyst is also a significant problem.However, the supported molybdenum carbide catalyst shows a much higher methane conversion, increasedselectivity and significantly improved catalytic stability. The characterization by XRD and BET specificarea measurements depict an improved dispersion of molybdenum carbide when using alumina as a carrier.The bulk or the supported molybdenum carbide exists in the β-Mo2C phase, while it is transformed intomolybdenum dioxide postcatalysis which is an important cause of molybdenum carbide deactivation.

  16. Methane partial oxidation by the lattice oxygen of the lanio₃δ perovskite. a pulse study

    OpenAIRE

    SIERRA GALLEGO, GERMÁN; BATIOT-DUPEYRAT, CATHERINE; MONDRAGÓN, FANOR

    2011-01-01

    LaNiO₃ perovskite was prepared by the selfcombustion method and tested as catalyst for CH4 activation using the oxygen lattice at 700°C and 800°C. Based on the non-stoichiometry experiments, the perovskite formula is written as La³⁺+ Ni³⁺ 0.37Ni²⁺ 0.63O2.68. When unreduced LaNiO3d perovskite is used, only type oxygen species were responsible for the partial CH₄ oxidation. Over non reduced perovskite high CH4 conversions to H₂ and CO were obtained. CH4 conversion and H₂, CO and CO₂, selectivit...

  17. Wet Aerobic Oxidation of Lignin into Aromatic Aldehydes Catalysed by a Perovskite-type Oxide: LaFe1-xCuxO3 (x=0, 0.1, 0.2

    Directory of Open Access Journals (Sweden)

    Lu Lin

    2009-07-01

    Full Text Available The perovskite-type oxide catalyst LaFe1-xCuxO3 (x=0, 0.1, 0.2 was prepared by the sol–gel method, and tested as a catalyst in the wet aerobic oxidation (WAO of lignin into aromatic aldehydes. The lignin conversion and the yield of each aromatic aldehyde were significantly enhanced in the catalytic process, compared with the non-catalyzed process. Moreover, it was shown that the stability of activity and structure of LaFe1-xCuxO3 (x=0, 0.1, 0.2 remained nearly unchanged after a series of successive recyclings of the catalytic reactions, indicating it was an efficient and recyclable heterogeneous catalyst for the conversion of lignin into aromatic aldehydes in the WAO process.

  18. Characteristic of nitrous oxide production in partial denitrification process with high nitrite accumulation.

    Science.gov (United States)

    Du, Rui; Peng, Yongzhen; Cao, Shenbin; Wang, Shuying; Niu, Meng

    2016-03-01

    Nitrous oxide (N2O) production during the partial denitrification process with nitrate (NO3(-)-N) to nitrite (NO2(-)-N) transformation ratio of 80% was investigated in this study. Results showed that N2O was seldom observed before complete depletion of NO3(-)-N, but it was closely related to the reduction of NO2(-)-N rather than NO3(-)-N. High COD/NO3(-)-N was in favor of N2O production in partial denitrification with high NO2(-)-N accumulation. It was seriously enhanced at constant acidic pH due to the free nitrous acid (FNA) inhibition. However, the N2O production was much lower at initial pH of 5.5 and 6.5 due to the pH increase during denitrification process. Significantly, the pH turning point could be chosen as a controlled parameter to denote the end of NO3(-)-N reduction, which could not only achieve high NO2(-)-N accumulation but also decrease the N2O production significantly for practical application.

  19. Characteristic of nitrous oxide production in partial denitrification process with high nitrite accumulation.

    Science.gov (United States)

    Du, Rui; Peng, Yongzhen; Cao, Shenbin; Wang, Shuying; Niu, Meng

    2016-03-01

    Nitrous oxide (N2O) production during the partial denitrification process with nitrate (NO3(-)-N) to nitrite (NO2(-)-N) transformation ratio of 80% was investigated in this study. Results showed that N2O was seldom observed before complete depletion of NO3(-)-N, but it was closely related to the reduction of NO2(-)-N rather than NO3(-)-N. High COD/NO3(-)-N was in favor of N2O production in partial denitrification with high NO2(-)-N accumulation. It was seriously enhanced at constant acidic pH due to the free nitrous acid (FNA) inhibition. However, the N2O production was much lower at initial pH of 5.5 and 6.5 due to the pH increase during denitrification process. Significantly, the pH turning point could be chosen as a controlled parameter to denote the end of NO3(-)-N reduction, which could not only achieve high NO2(-)-N accumulation but also decrease the N2O production significantly for practical application. PMID:26760756

  20. Simulation Studies of the Hydrogen Production from Methanol Partial Oxidation Steam Reforming by a Tubular Packed-bed Catalytic Reactor

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Hydrogen production by partial oxidation steam reforming of methanol over a Cu/ZnO/Al2 O3 cata lyst has been paid more and more attention. The chemical equilibria involved in the methanol partial oxidation steam reforming reaction network such as methanol partial oxidation, methanol steam reforming, decomposition of methanol and water-gas shift reaction have been examined over the ranges of temperature 473-1073 K under normal pressure. Based on the detailed kinetics of these reactions over a Cu/ZnO/Al2O3 catalyst, and from the basic concept of the effectiveness factor, the intraparticle diffusion limitations were taken into account. The effec tiveness factors for each reaction along the bed length were calculated. Then important results were offered for the simulation of this reaction process.

  1. SUPERCRITICAL WATER PARTIAL OXIDATION PHASE I - PILOT-SCALE TESTING / FEASIBILITY STUDIES FINAL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    SPRITZER,M; HONG,G

    2005-01-01

    Under Cooperative Agreement No. DE-FC36-00GO10529 for the Department of Energy, General Atomics (GA) is developing Supercritical Water Partial Oxidation (SWPO) as a means of producing hydrogen from low-grade biomass and other waste feeds. The Phase I Pilot-scale Testing/Feasibility Studies have been successfully completed and the results of that effort are described in this report. The Key potential advantages of the SWPO process is the use of partial oxidation in-situ to rapidly heat the gasification medium, resulting in less char formation and improved hydrogen yield. Another major advantage is that the high-pressure, high-density aqueous environment is ideal for reaching and gasifying organics of all types. The high water content of the medium encourages formation of hydrogen and hydrogen-rich products and is especially compatible with high water content feeds such as biomass materials. The high water content of the medium is also effective for gasification of hydrogen-poor materials such as coal. A versatile pilot plant for exploring gasification in supercritical water has been established at GA's facilities in San Diego. The Phase I testing of the SWPO process with wood and ethanol mixtures demonstrated gasification efficiencies of about 90%, comparable to those found in prior laboratory-scale SCW gasification work carreid out at the University of Hawaii at Manoa (UHM) as well as other biomass gasification experience with conventional gasifiers. As in the prior work at UHM, a significant amount of the hydrogen found in the gas phase products is derived from the water/steam matrix. The studies at UHM utilized an indirectly heated gasifier with an acitvated carbon catalyst. In contrast, the GA studies utilized a directly heated gasifier without catalyst, plus a surrogate waste fuel. Attainment of comparable gasification efficiencies without catalysis is an important advancement for the GA process, and opens the way for efficient hydrogen production from low

  2. Catalyst development and systems analysis of methanol partial oxidation for the fuel processor - fuel cell integration

    Energy Technology Data Exchange (ETDEWEB)

    Newson, E.; Mizsey, P.; Hottinger, P.; Truong, T.B.; Roth, F. von; Schucan, Th.H. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    Methanol partial oxidation (pox) to produce hydrogen for mobile fuel cell applications has proved initially more successful than hydrocarbon pox. Recent results of catalyst screening and kinetic studies with methanol show that hydrogen production rates have reached 7000 litres/hour/(litre reactor volume) for the dry pox route and 12,000 litres/hour/(litre reactor volume) for wet pox. These rates are equivalent to 21 and 35 kW{sub th}/(litre reactor volume) respectively. The reaction engineering problems remain to be solved for dry pox due to the significant exotherm of the reaction (hot spots of 100-200{sup o}C), but wet pox is essentially isothermal in operation. Analyses of the integrated fuel processor - fuel cell systems show that two routes are available to satisfy the sensitivity of the fuel cell catalysts to carbon monoxide, i.e. a preferential oxidation reactor or a membrane separator. Targets for individual system components are evaluated for the base and best case systems for both routes to reach the combined 40% efficiency required for the integrated fuel processor - fuel cell system. (author) 2 figs., 1 tab., 3 refs.

  3. Reduction of nitrous oxide emissions from partial nitrification process by using innovative carbon source (mannitol).

    Science.gov (United States)

    Zhang, Xinwen; Wang, Xiaoqing; Zhang, Jian; Huang, Xiaoyu; Wei, Dong; Lan, Wei; Hu, Zhen

    2016-10-01

    The purpose of this study was to evaluate the effect of mannitol as carbon source on nitrogen removal and nitrous oxide (N2O) emission during partial nitrification (PN) process. Laboratory-scale PN sequencing batch reactors (SBRs) were operated with mannitol and sodium acetate as carbon sources, respectively. Results showed that mannitol could remarkably reduce N2O-N emission by 41.03%, without influencing the removal efficiency of NH4(+)-N. However, it has a significant influence on nitrite accumulation ratio (NAR) and TN removal, which were 19.97% and 13.59% lower than that in PN with sodium acetate, respectively. Microbial analysis showed that the introduction of mannitol could increase the abundance of bacteria encoding nosZ genes. In addition, anti-oxidant enzymes (T-SOD, POD and CAT) activities were significantly reduced and the dehydrogenase activity had an obvious increase in mannitol system, indicating that mannitol could alleviate the inhibition of N2O reductase (N2OR) activities caused by high NO2(-)-N concentration. PMID:27423546

  4. Acetaldehyde partial oxidation on the Au(111) model catalyst surface: C-C bond activation and formation of methyl acetate as an oxidative coupling product

    Science.gov (United States)

    Karatok, Mustafa; Vovk, Evgeny I.; Shah, Asad A.; Turksoy, Abdurrahman; Ozensoy, Emrah

    2015-11-01

    Partial oxidation of acetaldehyde (CH3CHO) on the oxygen pre-covered Au(111) single crystal model catalyst was investigated via Temperature Programmed Desorption (TPD) and Temperature Programmed Reaction Spectroscopy (TPRS) techniques, where ozone (O3) was utilized as the oxygen delivery agent providing atomic oxygen to the reacting surface. We show that for low exposures of O3 and small surface oxygen coverages, two partial oxidation products namely, methyl acetate (CH3COOCH3) and acetic acid (CH3COOH) can be generated without the formation of significant quantities of carbon dioxide. The formation of methyl acetate as the oxidative coupling reaction product implies that oxygen pre-covered Au(111) single crystal model catalyst surface can activate C-C bonds. In addition to the generation of these products; indications of the polymerization of acetaldehyde on the gold surface were also observed as an additional reaction route competing with the partial and total oxidation pathways. The interplay between the partial oxidation, total oxidation and polymerization pathways reveals the complex catalytic chemistry associated with the interaction between the acetaldehyde and atomic oxygen on catalytic gold surfaces.

  5. Enzymatic Upgrading of Heavy Crudes via Partial Oxidation or Conversion of PAHs

    Energy Technology Data Exchange (ETDEWEB)

    Borole, A P; Davison, B H; Kuritz, T

    2002-07-01

    The objective of this program was to investigate new enzyme-based technologies for upgrading of heavy oils. Enzymes were selected for screening from those capable of conversion of polyaromatic hydrocarbons (PAHs) reported in the literature. Oxidative reactions of PAHs using hydrogen peroxide as an oxidant with conversion to partially oxidized products were used. The enzymes (lignin peroxidase, cytochrome c) were tested in various organic solvents and found to loose activity in pure organic solvents. A thermodynamic analysis revealed lack of effective interaction between the substrate and enzyme as the cause for low activity. The protein cytochrome c was modified to work in organic media by chemical hydrophobic group attachment. Two different modifications were made: attachment of polyethylene glycol (PEG) and alkyl groups. Alkyl groups, being small could be attached at interior locations within the core of the enzyme and possibly near the active site. Increase in the threshold solvent concentration where maximum enzyme activity occurred indicated potential of this strategy for effective enzyme-substrate interaction. Further improvements in enzyme activity called for other diverse methods due to the unavailability of sufficient chemical modification sites. Genetic techniques were therefore explored for further improvements. These experiments focused on cloning of a gene for the fungal enzyme lignin peroxidase (lip) into yeast Pichia pastoris, which would allow easy manipulation of the gene. However, differences in the fungal and yeast cellular machinery impeded significant expression of the fungal enzyme. Several strategies were explored to allow higher-level expression of the enzyme, which was required for enzyme improvement. The strategies used in this investigation are described in the report. Industrial in-kind support was available throughout the project period. review of the research results was carried out on a regular basis (bimonthly reports and annual

  6. Hybrid response surface methodology-genetic algorithm optimization of ultrasound-assisted transesterification of waste oil catalysed by immobilized lipase on mesoporous silica/iron oxide magnetic core-shell nanoparticles.

    Science.gov (United States)

    Karimi, Mahmoud; Keyhani, Alireza; Akram, Asadolah; Rahman, Masoud; Jenkins, Bryan; Stroeve, Pieter

    2013-01-01

    The production ofbiodiesel by transesterification of waste cooking oil (WCO) to partially substitute petroleum diesel is one of the measures for solving the twin problems of environment pollution and energy demand. An environmentally benign process for the enzymatic transesterification using immobilized lipase has attracted considerable attention for biodiesel production. Here, a superparamagnetic, high surface area substrate for lipase immobilization is evaluated. These immobilization substrates are composed of mesoporous silica/superparamagnetic iron oxide core-shell nanoparticles. The effects of methanol ratio to WCO, lipase concentration, water content and reaction time on the synthesis of biodiesel were analysed by utilizing the response surface methodology (RSM). A quadratic response surface equation for calculating fatty acid methyl ester (FAME) content as the objective function was established based on experimental data obtained in accordance with the central composite design. The RSM-based model was then used as the fitness function for genetic algorithm (GA) to optimize its input space. Hybrid RSM-GA predicted the maximum FAME content (91%) at the optimum level of medium variables: methanol ratio to WCO, 4.34; lipase content, 43.6%; water content, 10.22%; and reaction time, 6h. Moreover, the immobilized lipase could be used for four times without considerable loss of the activity. PMID:24350474

  7. Plasma-assisted partial oxidation of methane at low temperatures: numerical analysis of gas-phase chemical mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Goujard, Valentin; Nozaki, Tomohiro; Yuzawa, Shuhei; Okazaki, Ken [Department of Mechanical and Control Engineering, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, 1528552, Tokyo (Japan); Agiral, Anil, E-mail: tnozaki@mech.titech.ac.jp [Mesoscale Chemical Systems, MESA Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, PO Box 217, 7500 AE, Enschede (Netherlands)

    2011-07-13

    Methane partial oxidation was investigated using a plasma microreactor. The experiments were performed at 5 and 300 deg. C. Microreactor configuration allows an efficient evacuation of the heat generated by methane partial oxidation and dielectric barrier discharges, allowing at the same time a better temperature control. At 5 deg. C, liquid condensation of low vapour pressure compounds, such as formaldehyde and methanol, occurs. {sup 1}H-NMR analysis allowed us to demonstrate significant CH{sub 3}OOH formation during plasma-assisted partial oxidation of methane. Conversion and product selectivity were discussed for both temperatures. In the second part of this work, a numerical simulation was performed and a gas-phase chemical mechanism was proposed and discussed. From the comparison between the experimental results and the simulation it was found that CH{sub 3}OO{center_dot} formation has a determinant role in oxygenated compound production, since its fast formation disfavoured radical recombination. At 5 deg. C the oxidation leads mainly towards oxygenated compound formation, and plasma dissociation was the major phenomenon responsible for CH{sub 4} conversion. At 300 deg. C, higher CH{sub 4} conversion resulted from oxidative reactions induced by {center_dot}OH radicals with a chemistry predominantly oxidative, producing CO, H{sub 2}, CO{sub 2} and H{sub 2}O.

  8. Effect of calcination temperature and reaction conditions on methane partial oxidation using lanthanum-based perovskite as oxygen donor

    Institute of Scientific and Technical Information of China (English)

    DAI Xiaoping; YU Changchun; LI Ranjia; WU Qiong; SHI Kaijiao; HAO Zhengping

    2008-01-01

    We investigated the effect of calcination temperature, reaction temperature, and different amounts of replenished lattice oxygen on the partial oxidation of methane (POM) to synthesis gas using perovskite-type LaFeO3 oxide as oxygen donor instead of gaseous oxygen, which was prepared by the sol-gel method, and the oxides were characterized by XRD, TG/DTA, and BET. The results indicated that the particle size increased with the calcination temperature increasing, while BET and CH4 conversion declined with the calcination temperature increasing using LaFeO3 oxide as oxygen donor in the absence of gaseous oxygen. CO selectivity remained at a high level such as above 92%, and increased slightly as the calcination temperature increased. Exposure of LaFeO3 oxides to methane atmosphere enhanced the oxygen migration of in the bulk with time online owing to the loss of lattice oxygen and reduction of the oxidative stated Fe ion simultaneously. The high reaction temperature was favorable to the migration of oxygen species from the bulk toward the surface for the synthesis gas production with high CO selectivity. The product distribution and evolution for POM by sequential redox reaction was determined by amounts of replenished lattice oxygen with gaseous oxygen. The optimal process should decline the total oxidation of methane, and increase the selectivity of partial oxidation of methane.

  9. Partial Oxidation of Hydrocarbons in a Segmented Bed Using Oxide-based Catalysts and Oxygen-conducting Supports

    Science.gov (United States)

    Smith, Mark W.

    Two objectives for the catalytic reforming of hydrocarbons to produce synthesis gas are investigated herein: (1) the effect of oxygen-conducting supports with partially substituted mixed-metal oxide catalysts, and (2) a segmented bed approach using different catalyst configurations. Excess carbon deposition was the primary cause of catalyst deactivation, and was the focus of the experiments for both objectives. The formation and characterization of deposited carbon was examined after reaction for one of the selected catalysts to determine the quantity and location of the carbon on the catalyst surface leading to deactivation. A nickel-substituted barium hexaaluminate (BNHA), with the formula BaAl 11.6Ni0.4O18.8, and a Rh-substituted lanthanum zirconate pyrochlore (LCZR) with the formula La1.89Ca0.11 Zr1.89Rh0.11, were combined with two different doped ceria supports. These supports were gadolinium-doped ceria (GDC) and zirconium-doped ceria (ZDC). The active catalyst phases were combined with the supports in different ratios using different synthesis techniques. The catalysts were characterized using several different techniques and were tested under partial oxidation (POX) of n-tetradecane (TD), a diesel fuel surrogate. It was found that the presence of GDC and ZDC reduced the formation of carbon for both catalysts; the optimal ratio of catalyst to support was different for the hexaaluminate and the pyrochlore; a loading of 20 wt% of the pyrochlore with ZDC produced the most stable performance in the presence of common fuel contaminants (>50 h); and, the incipient wetness impregnation synthesis method of applying the active catalyst to the support produced more stable product yields than the catalyst prepared by a solid-state mixing technique. Different hexaaluminate and pyrochlore catalysts were used in different configurations in a segmented bed approach. The first strategy was to promote the indirect reforming mechanism by placing a combustion catalyst in the

  10. Partial oxidation of methanol on well-ordered V2O5(001)/Au(111) thin films

    NARCIS (Netherlands)

    Sturm, J. M.; Gobke, D.; Kuhlenbeck, H.; Dobler, J.; Reinhardt, U.; Ganduglia-Pirovano, M. V.; Sauer, J.; Freund, H. J.

    2009-01-01

    The partial oxidation of methanol to formaldehyde on well-ordered thin V2O5(001)films supported on Au(111) was studied. Temperature-programmed desorption shows that bulk-terminated surfaces are not reactive, whereas reduced surfaces produce formaldehyde. Formaldehyde desorption occurs between 400 K

  11. Oxidation of zirconium diboride-silicon carbide ceramics under an oxygen partial pressure of 200 Pa: Formation of zircon

    International Nuclear Information System (INIS)

    The formation and evolution of zircon during oxidation of ZrB2-20 vol.% SiC ceramics under a low oxygen partial pressure of 200 Pa is studied. The formation mechanism of zircon is proposed according to experimental results and thermodynamic consideration. And the main reason to the formation of zircon can be attributed to the active oxidation of SiC. Two steps can be divided for the formation and evolution of zircon: (1) nucleation from silica glass; and (2) crystal growth into prism like particles. Furthermore, the emergence of zircon significantly improves the oxidation resistance performance.

  12. An analytical model of hydrogen evolution and oxidation reactions on electrodes partially covered with a catalyst.

    Science.gov (United States)

    Kemppainen, Erno; Halme, Janne; Lund, Peter D

    2016-05-11

    Our previous theoretical study on the performance limits of the platinum (Pt) nanoparticle catalyst for the hydrogen evolution reaction (HER) had shown that the mass transport losses at a partially catalyst-covered planar electrode are independent of the catalyst loading. This suggests that the two-dimensional (2D) numerical model used could be simplified to a one-dimensional (1D) model to provide an easier but equally accurate description of the operation of these HER electrodes. In this article, we derive an analytical 1D model and show that it indeed gives results that are practically identical to the 2D numerical simulations. We discuss the general principles of the model and how it can be used to extend the applicability of existing electrochemical models of planar electrodes to low catalyst loadings suitable for operating photoelectrochemical devices under unconcentrated sunlight. Since the mass transport losses of the HER are often very sensitive to the H2 concentration, we also discuss the limiting current density of the hydrogen oxidation reaction (HOR) and how it is not necessarily independent of the reaction kinetics. The results give insight into the interplay of kinetic and mass-transport limitations at HER/HOR electrodes with implications for the design of kinetic experiments and the optimization of catalyst loadings in the photoelectrochemical cells.

  13. Simulation of partial oxidation of natural gas to synthesis gas using ASPEN PLUS

    Energy Technology Data Exchange (ETDEWEB)

    Khoshnoodi, M.; Lim, Y.S. [University of Sistan and Baluchestan, Zahedan (Iran). Dept. of Chemical Engineering

    1997-02-01

    The paper reports studies on the first stage of the SMDS Process for the conversion of natural gas to liquid fuels. In the SMDS process natural gas is first partially oxidized with pure oxygen to synthesis gas (a mixture of H{sub 2} and CO) which is then converted to high quality liquid transportation fuels by utilizing a modernized version of the Fischer-Tropsch reaction. The first stage of the process is synthesis gas production from natural gas. ASPEN PLUS equipped with a combustion databank was used for calculations. Concentrations of over 30 combustion species and radicals expected in the synthesis gas have been calculated at equilibrium and several non-equilibrium conditions. Using a sensitivity analysis tool, the relative feed flow rates and reactor parameters have been varied searching to maximize the CO/O{sub 2} yields as well as to minimize the undesired nitrogen compounds in the product stream. The optimum reactor temperature for maximizing the CO mode fraction in the synthesis gas was also calculated. 16 refs., 8 figs., 4 tabs.

  14. Inhibition effects in the partial oxidation of cyclohexane on polymer supported Co(II catalysts

    Directory of Open Access Journals (Sweden)

    MAJA ODOVIC

    2005-02-01

    Full Text Available Polymer supported catalysts with different contents of metal ions where synthesized by wet impregnation of the degassed support from ethanolic solutions of cobalt(II nitrate. Amacroreticular copolymer of poly-4-vinylpyridine with divinylbenzene was used as the support. The prepared catalysts were tested in the partial oxidation of cyclohexane to cyclohexanol and cyclohexanone. Activity tests were performed in a stainless steel, laboratory scale, stirred autoclave, in the semi batch regime under isothermal and non-isothermal conditions. Isothermal experiments where performed at 170 °C for 120 min. In the non-isothermal conditions. isothermal experiments where performed at 170 °C for 120 min. In the non-isothermal experiments, a constant heating rate of 0.3 degree/min was used in the range between 110 °C and 170 °C. Non-linear, least-squares analysis with the simplex optimization method and numerical simulation of the reaction model in each iterative step was used for the kinetic characterization of the process in a non-stationary, semi-batch regime. Apparent rate constants were obtained as an invariant measure of the catalytic system. Anon-linear effect of the content of metal ions on the reaction rate and on the ratio of the yield of the products was observed, which is attributed to a complex interactions between the reaction medium and the heterogeneous catalyst, including a catalyst-inhibition effect.

  15. An analytical model of hydrogen evolution and oxidation reactions on electrodes partially covered with a catalyst.

    Science.gov (United States)

    Kemppainen, Erno; Halme, Janne; Lund, Peter D

    2016-05-11

    Our previous theoretical study on the performance limits of the platinum (Pt) nanoparticle catalyst for the hydrogen evolution reaction (HER) had shown that the mass transport losses at a partially catalyst-covered planar electrode are independent of the catalyst loading. This suggests that the two-dimensional (2D) numerical model used could be simplified to a one-dimensional (1D) model to provide an easier but equally accurate description of the operation of these HER electrodes. In this article, we derive an analytical 1D model and show that it indeed gives results that are practically identical to the 2D numerical simulations. We discuss the general principles of the model and how it can be used to extend the applicability of existing electrochemical models of planar electrodes to low catalyst loadings suitable for operating photoelectrochemical devices under unconcentrated sunlight. Since the mass transport losses of the HER are often very sensitive to the H2 concentration, we also discuss the limiting current density of the hydrogen oxidation reaction (HOR) and how it is not necessarily independent of the reaction kinetics. The results give insight into the interplay of kinetic and mass-transport limitations at HER/HOR electrodes with implications for the design of kinetic experiments and the optimization of catalyst loadings in the photoelectrochemical cells. PMID:27137703

  16. Partially reduced graphene oxide based FRET on fiber-optic interferometer for biochemical detection

    Science.gov (United States)

    Yao, B. C.; Wu, Y.; Yu, C. B.; He, J. R.; Rao, Y. J.; Gong, Y.; Fu, F.; Chen, Y. F.; Li, Y. R.

    2016-03-01

    Fluorescent resonance energy transfer (FRET) with naturally exceptional selectivity is a powerful technique and widely used in chemical and biomedical analysis. However, it is still challenging for conventional FRET to perform as a high sensitivity compact sensor. Here we propose a novel ‘FRET on Fiber’ concept, in which a partially reduced graphene oxide (prGO) film is deposited on a fiber-optic modal interferometer, acting as both the fluorescent quencher for the FRET and the sensitive cladding for optical phase measurement due to refractive index changes in biochemical detection. The target analytes induced fluorescence recovery with good selectivity and optical phase shift with high sensitivity are measured simultaneously. The functionalized prGO film coated on the fiber-optic interferometer shows high sensitivities for the detections of metal ion, dopamine and single-stranded DNA (ssDNA), with detection limits of 1.2 nM, 1.3 μM and 1 pM, respectively. Such a prGO based ‘FRET on fiber’ configuration, bridging the FRET and the fiber-optic sensing technology, may serve as a platform for the realization of series of integrated ‘FRET on Fiber’ sensors for on-line environmental, chemical, and biomedical detection, with excellent compactness, high sensitivity, good selectivity and fast response

  17. Partial oxidation of TiN coating by hydrothermal treatment and ozone treatment to improve its osteoconductivity.

    Science.gov (United States)

    Shi, Xingling; Xu, Lingli; Le, Thi Bang; Zhou, Guanghong; Zheng, Chuanbo; Tsuru, Kanji; Ishikawa, Kunio

    2016-02-01

    Dental implants made of pure titanium suffer from abrasion and scratch during routine oral hygiene procedures. This results in an irreversible surface damage, facilitates bacteria adhesion and increases risk of peri-implantitis. To overcome these problems, titanium nitride (TiN) coating was introduced to increase surface hardness of pure titanium. However, the osteoconductivity of TiN is considered to be similar or superior to that of titanium and its alloys and therefore surface modification is necessary. In this study, TiN coating prepared through gas nitriding was partially oxidized by hydrothermal (HT) treatment and ozone (O3) treatment in pure water to improve its osteoconductivity. The effects of HT treatment and O3 treatment on surface properties of TiN were investigated and the osteoconductivity after undergoing treatment was assessed in vitro using osteoblast evaluation. The results showed that the critical temperature for HT treatment was 100°C since higher temperatures would impair the hardness of TiN coating. By contrast, O3 treatment was more effective in oxidizing TiN surfaces, improving its wettability while preserving its morphology and hardness. Osteoblast attachment, proliferation, alkaline phosphatase (ALP) expression and mineralization were improved on oxidized specimens, especially on O3 treated specimens, compared with untreated ones. These effects seemed to be consequences of partial oxidation, as well as improved hydrophilicity and surface decontamination. Finally, it was concluded that, partially oxidized TiN is a promising coating to be used for dental implant. PMID:26652406

  18. The influence of natural tocopherols during thermal oxidation of refined and partially hydrogenated soybean oils

    Directory of Open Access Journals (Sweden)

    Barrera-Arellano, D.

    2005-03-01

    Full Text Available Samples of refined and partially hydrogenated soybean oils, with iodine values between 60 and 130, tocopherol-stripped or not by aluminium oxide treatment, were submitted to thermal oxidation, at 180 °C (during for 10 hours. Samples were collected at 0, 2, 5, 8 and 10 hours, for the determination of dimers and polymers (degradation compounds and tocopherols. The relation of iodine value to the formation of dimers and polymers and the role of originally present tocopherols in the protection of fats and oils against thermal degradation was verified. The degradation curves for tocopherols showed that α and γ -tocopherols were destroyed faster than β and δ -tocopherols. In addition, the degradation rate of tocopherols was greater in the more saturated fats. The formation of dimers and polymers was greater in the oil than in the hydrogenated samples and in the samples treated with aluminium oxide with respect to the original, untreated samples.Muestras de aceites refinados y parcialmente hidrogenados de soja, con índices de yodo entre 60 y 130, tratadas o no con óxido de aluminio para eliminar los tocoferoles naturales presentes en los aceites, fueron sometidas a termoxidación, a 180 °C durante 10 horas. Se tomaron muestras en los tiempos 0, 2, 5, 8 y 10 horas, para determinación de dímeros y polímeros (compuestos de degradación y de tocoferoles. Se verificó la relación del índice de yodo con la formación de dímeros y polímeros, y también el papel de los tocoferoles originales del aceite y de las grasas en la protección contra la degradación térmica. Las curvas de degradación de los tocoferoles mostraron la destrucción más rápida de α y γ -tocoferoles, respecto a β y δ-tocoferoles. Además, la degradación de los tocoferoles ocurrió a mayor velocidad en las grasas más saturadas. La formación de dímeros y polímeros fue mayor en el aceite que en las muestras hidrogenadas y en las muestras tratadas

  19. Simulation Studies of the Hydrogen Production from Methanol Partial Oxidation Steam Reforming by a Tubular Packed-bed Catalytic Reactor*

    Institute of Scientific and Technical Information of China (English)

    蒋元力; 林美淑; 金东显

    2001-01-01

    Hydrogen production by partial oxidation steam reforming of methanol over a Cu/ZnO/Al2O3 cata-lyst has been paid more and more attention. The chemical equilibria involved in the methanol pvxtial oxidation steam reforming reaction network such as methanol partial oxidation, methanol steam reforming, decomposition of methanol and water-gas shift reaction have been examined over the ranges of temperature 473---1073 K under normal pressure. Based on the detailed kinetics of these reactions over a Cu/ZnO/Al2O3 catalyst, and from the basic concept of the effectiveness factor, the intraparticle diffusion limitations were taken into account. The effectiveness factors for each reaction along the bed length were calculated. Then important results were offered for the simulation of this reaction process.

  20. Oscillatory Behavior during the Catalytic Partial Oxidation of Methane: Following Dynamic Structural Changes of Palladium Using the QEXAFS Technique

    DEFF Research Database (Denmark)

    Stoetzel, Jan; Frahm, Ronald; Kimmerle, Bertram;

    2012-01-01

    investigated using spatially and time-resolved in situ quick scanning X-ray absorption spectroscopy with online mass spectrometry. The dynamic methane conversion oscillated between an inactive state, where only combustion occurred, and an active state, after ignition, where partial oxidation of methane...... by the oven temperature than the ignition behavior of the catalytic partial oxidation of methane. This indicates that deactivation is caused by an autoreduction of the palladium at the beginning of the catalyst bed due to the high temperature achieved by total oxidation of methane....... of the Pd particles at increasing age of the catalyst was observed, which leads to a lower oscillation frequency. Effects of particle size, oven temperature, and oxygen/methane ratio on the oscillation behavior were studied in detail. The deactivation period (reoxidation of Pd) was much less influenced...

  1. Palladium-catalysed ortho arylation of acetanilides

    Indian Academy of Sciences (India)

    Guo-zhen zhang; Cheng-Qun Chen; Xin-Hua Feng; Guo-Sheng Huang

    2010-03-01

    The palladium-catalysed direct arylation of acetanilides by using C-H activation methodology has been demonstrated. Several acetanilides were coupled with aryl iodides in the presence of 10 mol% of Pd(OAc)2, 1.0 equiv of Cu(OTf)2, and 0.6 equiv of Ag2O to afford the corresponding products in moderate to excellent yields. The results showed that the amount of Ag2O was important for this protocol.

  2. Hemicellulose hydrolysis catalysed by solid acids

    OpenAIRE

    Carà, P.D..; Pagliaro, M.; Elmekawy, A.; Brown, D R; Verschuren, P.; Shiju, N.R.; Rothenberg, G.

    2013-01-01

    Depolymerising hemicellulose into platform sugar molecules is a key step in developing the concept of an integrated biorefinery. This reaction is traditionally catalysed by either enzymes or homogeneous mineral acids. We compared various solid catalysts for hemicellulose hydrolysis, running reactions in water, under neutral pH and relatively mild temperature and pressure (120 degrees C and 10 bar) conditions. Sulphonated resins are highly active, but they leach out sulphonic groups. Sulphonat...

  3. CO2 separation by calcium looping from full and partial fuel oxidation processes

    International Nuclear Information System (INIS)

    This thesis work deals with the research and development of calcium looping process for CO2 separation from full and partial fuel oxidation based power generation systems. CO2 is the main greenhouse gas and undoubtedly a major contributor to the global warming. It is estimated that more than one third of the total anthropogenic CO2 emissions come from fossil fuel based heat and power generation. Moreover, fossil fuels are unlikely to be phased out rapidly, since developing alternative energy sources not only take time but also require huge investments and infrastructure. An alternative way to reduce emissions in a medium term is to capture the CO2 from fossil fueled power plants and store it away from the atmosphere. This process system combining a bunch of technologies is called carbon capture and storage (CCS). CO2 capture is an important and costly part of CCS and an array of technologies is considered for this. Calcium looping (CaL) is one of such and seems to offer effective and efficient CO2 separation from fuel oxidation processes. CaL process involves separation of CO2 at high temperatures (600-700 C) by calcium sorbents (CaO). CO2 reacts with CaO in a carbonation process and produces CaCO3. In a subsequent thermal regeneration (>850 C) called calcination, the CO2 is released from CaCO3. By alternating carbonations and calcinations over multiple cycles, CO2 is separated from a gas stream. Moreover, the CaL is realised in industrial scale with dual fluidised bed reactors for CO2 capture (the carbonator) and sorbent regeneration (the calciner). As a process in the development, research is still required in many aspects from thermodynamic modeling to experimental studies. Research works have been carried out in process simulations, sorbent reactivity and optimisation studies in a controlled reactor environment and process parametric studies in a semi-pilot scale CaL test facility. ASPEN Plus power plant simulations integrating the CaL based CO2 capture

  4. Effect of cerium addition on oxidation behavior of 2SCr20Ni alloy under lowoxygen partial pressure

    Institute of Scientific and Technical Information of China (English)

    SHAO Mingzeng; CUI Lishan; ZHENG Yanjun; XING Linlin

    2012-01-01

    The influence of Ce addition on the oxidation behavior of 25Cr20Ni alloy at 950 ℃ under low oxygen partial pressure was investigated.The oxidized samples were characterized by using X-ray diffraction (XRD),scanning electron microscopy (SEM),energy dispersive X-ray spectroscopy (EDS),and scratch tester to obtain the oxide phases,morphology,thickness,composition and adhesion property of the oxide scales.The experiment results indicated that a small amount of Ce addition (0.02 wt.% or 0.05 wt.%) promoted oxidation resistance and inhibited the growth of the needlelike oxide.The Ce addition also decreased the formation of MnCr2O4 but promoted the SiO2 formation underneath the Cr2O3,which largely contributed to the improvement of oxide scale spallation resistance.For the sample with 0.3 wt.% Ce addition,the oxidation rate significantly increased and the spallation resistance of the oxide scale decreased.

  5. Uranium and minor-element partitioning in Fe-Ti oxides and zircon from partially melted granodiorite, Crater Lake, Oregon

    Science.gov (United States)

    Tourrette, T.Z.L.; Burnett, D.S.; Bacon, C.R.

    1991-01-01

    Crystal-liquid partitioning in Fe-Ti oxides and zircon was studied in partially melted granodiorite blocks ejected during the climactic eruption of Mt. Mazama (Crater Lake), Oregon. The blocks, which contain up to 33% rhyolite glass (75 wt% SiO2), are interpreted to be portions of the magma chamber walls that were torn off during eruption. The glass is clear and well homogenized for all measured elements except Zr. Results for Fe-Ti oxides give DUoxide/liq ??? 0.1. Partitioning of Mg, Mn, Al, Si, V, and Cr in Fe-Ti oxides indicates that grains surrounded by glass are moderately well equilibrated with the melt for many of the minor elements, while those that are inclusions in relict plagioclase are not. Uranium and ytterbium inhomogeneities in zircons indicate that the zircons have only partially equilibrated with the melt and that uranium appears to have been diffusing out of the zircons faster than the zircons were dissolving. Minimum U, Y, and P concentrations in zircons give maximum DUzrc/liq = 13,DYzrc/liq = 23, and DPzrc/liq = 1, but these are considerably lower than reported by other workers for U and Y. Based on our measurements and given their low abundances in most rocks, Fe-Ti oxides probably do not play a major role in U-Th fractionation during partial melting. The partial melts were undersaturated with zircon and apatite, but both phases are present in our samples. This demonstrates an actual case of non-equilibrium source retention of accessory phases, which in general could be an important trace-element fractionation mechanism. Our results do not support the hypothesis that liquid structure is the dominant factor controlling trace-element partitioning in high-silica rhyolites. Rough calculations based on Zr gradients in the glass indicate that the samples could have been partially molten for 800 to 8000 years. ?? 1991.

  6. Partial Oxidation of Methane to Syngas Using Lattice Oxygen of La1-xSrxFeO3 Perovskite Oxide Catalysts Instead of Molecular Oxygen

    Institute of Scientific and Technical Information of China (English)

    Ranjia Li; Changchun Yu; Shikong Shen

    2002-01-01

    Catalytic partial oxidation of methane to syngas using the lattice oxygen of La1-xSrxFeO3 perovskite oxide catalysts in place of molecular oxygen was studied. La1-xSrxFeO3 (x=0, 0.1, 0.2,0.5) perovskite oxides were prepared by the "auto-combustion method". XRD analysis showed that all La1-xSrxFeO3 samples have a single-phase perovskite-type oxide. The redox properties of the catalysts were investigated by temperature programmed reduction with hydrogen (H2-TPR). Reducibility of the catalysts increase with the increasing of the Sr2+ content. The oxygen species of the catalysts and their reaction with CH4 were studied by the temperature programmed surface reaction (CH4-TPSR). In the absence of gas phase oxygen, there exist two kinds of oxygen species on the catalysts. One kind of the oxygen species with strong oxidative ability is produced first, which can oxidize CH4 completely to CO2 and H2O.Then, the second oxygen species with weak oxidative ability is formed, which can oxidize CH4 partially to CO and H2 with high selectivity. The number of the oxygen species with strong oxidative ability in the CH4-TPSR tends to become zero at low x values (x≤0.1). Under suitable reaction conditions, switching alternatively the reactions of 11% O2-Ar and 11% CH4-He over a La0.sSr0.2FeO3 catalyst at 900 ℃ allows methane to be selectively converted to synthesis gas (CH4 conversion ~90%, CO selectivity >93%) using the lattice oxygen of the perovskite oxide catalyst in a redox mode.

  7. On the formation of nitrogen oxides during the combustion of partially pre-vaporized droplets

    Energy Technology Data Exchange (ETDEWEB)

    Moesl, Klaus Georg

    2012-12-12

    This study contributes to the topic of nitrogen oxide (NO{sub x}) formation at the level of single droplet and droplet array combustion. The influence of the degree of droplet vaporization and the influence of ambient conditions on NO{sub x} emissions are studied in detail by experiments as well as by numerical simulations. Consequently, this study illustrates correlations and dependencies of the most relevant parameters with respect to the formation of NO{sub x}. It merges the fields of droplet pre-vaporization, ignition, combustion, and exhaust gas formation, including a sophisticated approach to NO{sub x} determination. Even though the study was conducted in order to help understand the fundamental process of burning idealized droplets, the processes in spray combustion have also been taken into consideration within its scope. The portability of results obtained from those idealized droplet burning regimes is evaluated for real applications. Thus, this study may also help to derive design recommendations for liquid-fueled combustion devices. While the experimental part focuses on droplet array combustion, the numerical part highlights spherically symmetric single droplet combustion. By performing experiments in a microgravity environment, quasi-spherical conditions were facilitated for droplet burning, and comparability was provided for the experimental and numerical results. A novelty of the numerical part is the investigation of mechanisms of NO{sub x} formation under technically relevant conditions. This includes partial pre-vaporization of the droplets as well as droplet combustion in a hot exhaust gas environment, such as an aero-engine. The results show that the trade-off between ambient temperature and available oxygen determines the NO{sub x} formation of droplets burning in hot exhaust gas. If the ambient temperature is high and there is still sufficient oxygen for full oxidation of the fuel provided by the droplet, the maximum of NOx formation is

  8. Potential of using cerium oxide nanoparticles for protecting healthy tissue during accelerated partial breast irradiation (APBI).

    Science.gov (United States)

    Ouyang, Zi; Mainali, Madan Kumar; Sinha, Neeharika; Strack, Guinevere; Altundal, Yucel; Hao, Yao; Winningham, Thomas Andrew; Sajo, Erno; Celli, Jonathan; Ngwa, Wilfred

    2016-04-01

    The purpose of this study is to investigate the feasibility of using cerium oxide nanoparticles (CONPs) as radical scavengers during accelerated partial breast irradiation (APBI) to protect normal tissue. We hypothesize that CONPs can be slowly released from the routinely used APBI balloon applicators-via a degradable coating-and protect the normal tissue on the border of the lumpectomy cavity over the duration of APBI. To assess the feasibility of this approach, we analytically calculated the initial concentration of CONPs required to protect normal breast tissue from reactive oxygen species (ROS) and the time required for the particles to diffuse to various distances from the lumpectomy wall. Given that cerium has a high atomic number, we took into account the possible inadvertent dose enhancement that could occur due to the photoelectric interactions with radiotherapy photons. To protect against a typical MammoSite treatment fraction of 3.4Gy, 5ng·g(-1) of CONPs is required to scavenge hydroxyl radicals and hydrogen peroxide. Using 2nm sized NPs, with an initial concentration of 1mg·g(-1), we found that 2-10days of diffusion is required to obtain desired concentrations of CONPs in regions 1-2cm away from the lumpectomy wall. The resultant dose enhancement factor (DEF) is less than 1.01 under such conditions. Our results predict that CONPs can be employed for radioprotection during APBI using a new design in which balloon applicators are coated with the NPs for sustained/controlled in-situ release from within the lumpectomy cavity. PMID:27053452

  9. Structure and performance of cobalt and nickel catalysts for hydrogen generation from bio-ethanol partial oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Ehrlich, Heike; Kraleva, Elka [Rostock Univ. (Germany). Leibniz-Institut fuer Katalyse

    2012-07-01

    A hydrogen and CO rich fuel gas used for SOFC applications is obtained directly from ethanol by partial oxidation. Low-cost cobalt and nickel metals supported on different mixed oxides were found to be highly active catalysts in this reaction. The ethanol conversion started above 350 C and increased with increasing reaction temperature. Hydrogen and carbon monoxide were the predominant products at temperatures above 500 C. Among the catalysts studied, CoAlZn and NiAlZn mixed oxides showed to provide the highest H{sub 2} and CO selectivity. By the use of a sol-gel method for catalyst preparation the drawback of oxide sintering at high temperature could be eliminated. It was found that phase composition of the catalysts and their thermal stability depends significantly on the preparation method and chemical composition. (orig.)

  10. SUPERCRITICAL WATER PARTIAL OXIDATION PHASE I - PILOT-SCALE TESTING/FEASIBILTY SUDIES FINAL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    SPRITZER.M; HONG,G

    2005-01-01

    General Atomics (GA) is developing Supercritical Water Partial Oxidation (SWPO) as a means of producing hydrogen from low-grade biomass and other waste feeds. The Phase I Pilot-scale Testing/Feasibility Studies have been successfully completed and the results of that effort are described in this report. The key potential advantage of the SWPO process is the use of partial oxidation in-situ to rapidly heat the gasification medium, resulting in less char formation and improved hydrogen yield. Another major advantage is that the high-pressure, high-density aqueous environment is ideal for reacting and gasifying organics of all types. The high water content of the medium encourages formation of hydrogen and hydrogen-rich products and is especially compatible with high water content feeds such as biomass materials. The high water content of the medium is also effective for gasification of hydrogen-poor materials such as coal. A versatile pilot plant for exploring gasification in supercritical water has been established at GA's facilities in San Diego. The Phase I testing of the SWPO process with wood and ethanol mixtures demonstrated gasification efficiencies of about 90%, comparable to those found in prior laboratory-scale SCW gasification work carried out at the University of Hawaii at Manoa (UHM), as well as other biomass gasification experience with conventional gasifiers. As in the prior work at UHM, a significant amount of the hydrogen found in the gas phase products is derived from the water/steam matrix. The studies at UHM utilized an indirectly heated gasifier with an activated carbon catalyst. In contrast, the GA studies utilized a directly heated gasifier without catalyst, plus a surrogate waste fuel. Attainment of comparable gasification efficiencies without catalysis is an important advancement for the GA process, and opens the way for efficient hydrogen production from low-value, dirty feed materials. The Phase I results indicate that a practical

  11. SUPERCRITICAL WATER PARTIAL OXIDATION PHASE I - PILOT-SCALE TESTING/FEASIBILTY SUDIES FINAL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    SPRITZER.M; HONG,G

    2005-01-01

    General Atomics (GA) is developing Supercritical Water Partial Oxidation (SWPO) as a means of producing hydrogen from low-grade biomass and other waste feeds. The Phase I Pilot-scale Testing/Feasibility Studies have been successfully completed and the results of that effort are described in this report. The key potential advantage of the SWPO process is the use of partial oxidation in-situ to rapidly heat the gasification medium, resulting in less char formation and improved hydrogen yield. Another major advantage is that the high-pressure, high-density aqueous environment is ideal for reacting and gasifying organics of all types. The high water content of the medium encourages formation of hydrogen and hydrogen-rich products and is especially compatible with high water content feeds such as biomass materials. The high water content of the medium is also effective for gasification of hydrogen-poor materials such as coal. A versatile pilot plant for exploring gasification in supercritical water has been established at GA's facilities in San Diego. The Phase I testing of the SWPO process with wood and ethanol mixtures demonstrated gasification efficiencies of about 90%, comparable to those found in prior laboratory-scale SCW gasification work carried out at the University of Hawaii at Manoa (UHM), as well as other biomass gasification experience with conventional gasifiers. As in the prior work at UHM, a significant amount of the hydrogen found in the gas phase products is derived from the water/steam matrix. The studies at UHM utilized an indirectly heated gasifier with an activated carbon catalyst. In contrast, the GA studies utilized a directly heated gasifier without catalyst, plus a surrogate waste fuel. Attainment of comparable gasification efficiencies without catalysis is an important advancement for the GA process, and opens the way for efficient hydrogen production from low-value, dirty feed materials. The Phase I results indicate that a practical

  12. Improved Efficiency for Partial Oxidation of Methane by Controlled Copper Deposition on Surface‐Modified ZSM‐5

    OpenAIRE

    Sheppard, Thomas; Daly, Helen; Goguet, Alexandre; Thompson, Jillian

    2015-01-01

    Abstract The mono(μ‐oxo) dicopper cores present in the pores of Cu‐ZSM‐5 are active for the partial oxidation of methane to methanol. However, copper on the external surface reduces the ratio of active, selective sites to unselective sites. More efficient catalysts are obtained by controlling the copper deposition during synthesis. Herein, the external exchange sites of ZSM‐5 samples were passivated by bis(trimethylsilyl) trifluoroacetamide (BSTFA) followed by calcination, promoting selective...

  13. Alkene Cleavage Catalysed by Heme and Nonheme Enzymes: Reaction Mechanisms and Biocatalytic Applications

    Directory of Open Access Journals (Sweden)

    Francesco G. Mutti

    2012-01-01

    Full Text Available The oxidative cleavage of alkenes is classically performed by chemical methods, although they display several drawbacks. Ozonolysis requires harsh conditions (−78°C, for a safe process and reducing reagents in a molar amount, whereas the use of poisonous heavy metals such as Cr, Os, or Ru as catalysts is additionally plagued by low yield and selectivity. Conversely, heme and nonheme enzymes can catalyse the oxidative alkene cleavage at ambient temperature and atmospheric pressure in an aqueous buffer, showing excellent chemo- and regioselectivities in certain cases. This paper focuses on the alkene cleavage catalysed by iron cofactor-dependent enzymes encompassing the reaction mechanisms (in case where it is known and the application of these enzymes in biocatalysis.

  14. Effect of oxygen partial pressure on optical properties of gadolinium oxide thin films prepared by pulsed laser deposition

    International Nuclear Information System (INIS)

    Gadolinium oxide (Gd2O3) is a rare earth oxide existing in three different phases such as cubic, monoclinic and hexagonal structure at ambient pressure. Properties such as high thermal and chemical stability, wide band gap and high dielectric constant (∼16) make it a suitable candidate material for protective coating, optical coating and dielectric material in CMOS, as well as in device applications. Gd2O3 thin films were deposited on quartz substrates at different oxygen partial pressures and at a substrate temperature of 573 K by pulsed laser deposition. XRD pattern shows the presence of both monoclinic and cubic phases of gadolinium oxide. Optical properties of the films such as transmittance and absorbance were measured by UV-Vis spectrophotometer. The oxygen partial pressure during deposition seems to affect the optical properties such as refractive index and transmittance. For instance, the films show a strong absorption at ∼216 nm and a decrease in transmittance value from 80% to 70% with decrease in oxygen partial pressure. (author)

  15. Anaerobic oxidation of p-cresol mediated by a partially purified methylhydroxylase from a denitrifying bacterium.

    OpenAIRE

    Bossert, I D; Whited, G; Gibson, D T; Young, L. Y.

    1989-01-01

    Anoxic cell extracts of a denitrifying bacterial isolate (PC-07) were shown to oxidize p-cresol to p-hydroxybenzoate. Oxidation of the substrate was independent of molecular oxygen and required nitrate as the natural terminal electron acceptor. Two enzyme activities were implicated in the pathway utilized by PC-07. A p-cresol methylhydroxylase mediated the oxidation of p-cresol to p-hydroxybenzaldehyde, which was further oxidized to p-hydroxybenzoate by an NAD+-dependent dehydrogenase. The PC...

  16. Performance of an oxygen-permeable membrane reactor for partial oxidation of methane in coke oven gas to syngas

    Energy Technology Data Exchange (ETDEWEB)

    Yuwen Zhang; Jiao Liu; Weizhong Ding; Xionggang Lu [Shanghai University, Shanghai (China). Shanghai Key Laboratory of Modern Metallurgy & Materials Processing

    2011-01-15

    Perovskite-type oxygen-permeable membrane reactors of BaCo{sub 0.7}Fe{sub 0.2}Nb{sub 0.1}O{sub 3-delta} packed with Ni-based catalyst had high oxygen permeability and could be used for syngas production by partial oxidation of methane in coke oven gas (COG). The BCFNO membrane itself had a poor catalytic activity to partial oxidation of CH{sub 4} in COG. After the catalyst was packed on the membrane surface, 92% of methane conversion, 90% of H{sub 2} selectivity, 104% of CO selectivity and as high as 15 ml/cm{sup 2}/min of oxygen permeation flux were obtained at 1148 K. During continuously operating for 550 h at 1148 K, no degradation of performance of the BCFNO membrane reactor was observed under the condition of hydrogen-rich COG. The possible reaction pathways were proposed to be an oxidation-reforming process. The oxidation of H{sub 2} in COG with the surface oxygen on the permeation side improves the oxygen flux through the membrane, and H{sub 2}O reacts with CH{sub 4} by reforming reactions to form H{sub 2} and CO. 29 refs., 7 figs., 1 tab.

  17. Oscillations during partial oxidation of methane to synthesis gas over Ru/Al_2O_3 catalyst

    Institute of Scientific and Technical Information of China (English)

    Meiliu Wang; Weizheng Weng; Haozhuan Zheng; Xiaodong Yi; Chuanjing Huang; Huilin Wan

    2009-01-01

    Oscillations in temperatures of catalyst bed as well as concentrations of gas phase species at the exit of reactor were observed during the partial oxidation of methane to synthesis gas over Ru/Al_2O_3 in the temperature range of 600 to 850 ℃. XRD,H_2-TPR and in situ Raman techniques was used to characterize the catalyst. Two types of ruthenium species,i.e. the rutbenium species weakly interacted with Al_2O_3 and that strongly interacted with the support,were identified by H2-TPR experiment. These species are responsible for two types of oscillation profiles observed during the reaction. The oscillations were the result of these ruthenium species switching cyclically between the oxidized state and the reduced state under the reaction condition. These cyclic transformations,in turn,were the result of temperature variations caused by the varying levels of the strongly exothermic CH_4 combustion and the highly endothermic CH4 reforming (with H_2O and CO_2) reactions (or the less exothermic direct partial oxidation of methane to CO and H_2),which were favored by the oxidized and the metallic sites,respectively. The major pathway of synthesis gas formation over the catalyst was via the combustion-reforming mechanism.

  18. CO{sub 2} separation by calcium looping from full and partial fuel oxidation processes

    Energy Technology Data Exchange (ETDEWEB)

    Sivalingam, Senthoorselvan

    2013-06-05

    This thesis work deals with the research and development of calcium looping process for CO{sub 2} separation from full and partial fuel oxidation based power generation systems. CO{sub 2} is the main greenhouse gas and undoubtedly a major contributor to the global warming. It is estimated that more than one third of the total anthropogenic CO{sub 2} emissions come from fossil fuel based heat and power generation. Moreover, fossil fuels are unlikely to be phased out rapidly, since developing alternative energy sources not only take time but also require huge investments and infrastructure. An alternative way to reduce emissions in a medium term is to capture the CO{sub 2} from fossil fueled power plants and store it away from the atmosphere. This process system combining a bunch of technologies is called carbon capture and storage (CCS). CO{sub 2} capture is an important and costly part of CCS and an array of technologies is considered for this. Calcium looping (CaL) is one of such and seems to offer effective and efficient CO{sub 2} separation from fuel oxidation processes. CaL process involves separation of CO{sub 2} at high temperatures (600-700 C) by calcium sorbents (CaO). CO{sub 2} reacts with CaO in a carbonation process and produces CaCO{sub 3}. In a subsequent thermal regeneration (>850 C) called calcination, the CO{sub 2} is released from CaCO{sub 3}. By alternating carbonations and calcinations over multiple cycles, CO{sub 2} is separated from a gas stream. Moreover, the CaL is realised in industrial scale with dual fluidised bed reactors for CO{sub 2} capture (the carbonator) and sorbent regeneration (the calciner). As a process in the development, research is still required in many aspects from thermodynamic modeling to experimental studies. Research works have been carried out in process simulations, sorbent reactivity and optimisation studies in a controlled reactor environment and process parametric studies in a semi-pilot scale CaL test facility

  19. Stable ultrathin partially oxidized copper film electrode for highly efficient flexible solar cells

    OpenAIRE

    ZHAO Guoqing; Wang, Wei; Bae, Tae-Sung; Lee, Sang-Geul; Mun, ChaeWon; Lee, Sunghun; Yu, Huashun; Lee, Gun-Hwan; Song, Myungkwan; Yun, Jungheum

    2015-01-01

    Advances in flexible optoelectronic devices have led to an increasing need for developing highly efficient, low-cost, flexible transparent conducting electrodes. Copper-based electrodes have been unattainable due to the relatively low optical transmission and poor oxidation resistance of copper. Here, we report the synthesis of a completely continuous, smooth copper ultra-thin film via limited copper oxidation with a trace amount of oxygen. The weakly oxidized copper thin film sandwiched betw...

  20. Symbiosis catalyses niche expansion and diversification.

    Science.gov (United States)

    Joy, Jeffrey B

    2013-04-01

    Interactions between species are important catalysts of the evolutionary processes that generate the remarkable diversity of life. Symbioses, conspicuous and inherently interesting forms of species interaction, are pervasive throughout the tree of life. However, nearly all studies of the impact of species interactions on diversification have concentrated on competition and predation leaving unclear the importance of symbiotic interaction. Here, I show that, as predicted by evolutionary theories of symbiosis and diversification, multiple origins of a key innovation, symbiosis between gall-inducing insects and fungi, catalysed both expansion in resource use (niche expansion) and diversification. Symbiotic lineages have undergone a more than sevenfold expansion in the range of host-plant taxa they use relative to lineages without such fungal symbionts, as defined by the genetic distance between host plants. Furthermore, symbiotic gall-inducing insects are more than 17 times as diverse as their non-symbiotic relatives. These results demonstrate that the evolution of symbiotic interaction leads to niche expansion, which in turn catalyses diversification. PMID:23390106

  1. A novel partial SOI LDMOSFET with periodic buried oxide for breakdown voltage and self heating effect enhancement

    Science.gov (United States)

    Jamali Mahabadi, S. E.; Rajabi, Saba; Loiacono, Julian

    2015-09-01

    In this paper a partial silicon on insulator (PSOI) lateral double diffused metal oxide semiconductor field effect transistor (LDMOSFET) with periodic buried oxide layer (PBO) for enhancing breakdown voltage (BV) and self-heating effects (SHEs) is proposed for the first time. This new structure is called periodic buried oxide partial silicon on insulator (PBO-PSOI). In this structure, periodic small pieces of SiO2 were used as the buried oxide (BOX) layer in PSOI to modulate the electric field in the structure. It was demonstrated that the electric field is distributed more evenly by producing additional electric field peaks, which decrease the common peaks near the drain and gate junctions in the PBO-PSOI structure. Hence, the area underneath the electric field curve increases which leads to higher breakdown voltage. Also a p-type Si window was introduced in the source side to force the substrate to share the vertical voltage drop, leading to a higher vertical BV. Furthermore, the Si window under the source and those between periodic pieces of SiO2 create parallel conduction paths between the active layer and substrate thereby alleviating the SHEs. Simulations with the two dimensional ATLAS device simulator from the Silvaco suite of simulation tools show that the BV of PBO-PSOI is 100% higher than that of the conventional partial SOI (C-PSOI) structure. Furthermore the PBO-PSOI structure alleviates SHEs to a greater extent than its C-PSOI counterpart. The achieved drain current for the PBO-PSOI structure (100 μA), at drain-source voltage of VDS = 100 V and gate-source voltage of VGS = 25 V, is shown to be significantly larger than that in C-PSOI and fully depleted SOI (FD-SOI) structures (87 μA and 51 μA respectively). Drain current can be further improved at the expense of BV by increasing the doping of the drift region.

  2. Integrated Biomass Gasification with Catalytic Partial Oxidation for Selective Tar Conversion

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lingzhi; Wei, Wei; Manke, Jeff; Vazquez, Arturo; Thompson, Jeff; Thompson, Mark

    2011-05-28

    requirement for commercial deployment of biomass-based power/heat co-generation and biofuels production. There are several commonly used syngas clean-up technologies: (1) Syngas cooling and water scrubbing has been commercially proven but efficiency is low and it is only effective at small scales. This route is accompanied with troublesome wastewater treatment. (2) The tar filtration method requires frequent filter replacement and solid residue treatment, leading to high operation and capital costs. (3) Thermal destruction typically operates at temperatures higher than 1000oC. It has slow kinetics and potential soot formation issues. The system is expensive and materials are not reliable at high temperatures. (4) In-bed cracking catalysts show rapid deactivation, with durability to be demonstrated. (5) External catalytic cracking or steam reforming has low thermal efficiency and is faced with problematic catalyst coking. Under this program, catalytic partial oxidation (CPO) is being evaluated for syngas tar clean-up in biomass gasification. The CPO reaction is exothermic, implying that no external heat is needed and the system is of high thermal efficiency. CPO is capable of processing large gas volume, indicating a very compact catalyst bed and a low reactor cost. Instead of traditional physical removal of tar, the CPO concept converts tar into useful light gases (eg. CO, H2, CH4). This eliminates waste treatment and disposal requirements. All those advantages make the CPO catalytic tar conversion system a viable solution for biomass gasification downstream gas clean-up. This program was conducted from October 1 2008 to February 28 2011 and divided into five major tasks. - Task A: Perform conceptual design and conduct preliminary system and economic analysis (Q1 2009 ~ Q2 2009) - Task B: Biomass gasification tests, product characterization, and CPO tar conversion catalyst preparation. This task will be conducted after completing process design and system economics analysis

  3. Potential hydrogen and oxygen partial pressures in legacy plutonium oxide packages at Oak Ridge

    Energy Technology Data Exchange (ETDEWEB)

    Veirs, Douglas K. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-07-07

    An approach to estimate the maximum hydrogen and oxygen partial pressures within sealed containers is described and applied to a set of packages containing high-purity plutonium dioxide. The approach uses experimentally determined maximum hydrogen and oxygen partial pressures and scales the experimentally determined pressures to the relevant packaged material properties. The important material properties are the specific wattage and specific surface area (SSA). Important results from the experimental determination of maximum partial pressures are (1) the ratio of hydrogen to oxygen is stoichiometric, and (2) the maximum pressures increase with increasing initial rates of production. The material properties that influence the rates are the material specific wattage and the SSA. The unusual properties of these materials, high specific wattage and high SSA, result in higher predicted maximum pressures than typical plutonium dioxide in storage. The pressures are well within the deflagration range for mixtures of hydrogen and oxygen.

  4. The Effect of Nb Loading on Catalytic Properties of Ni/Ce0.75Zr0.25O2 Catalyst for Methane Partial Oxidation

    Institute of Scientific and Technical Information of China (English)

    Sitthiphong Pengpanich; Vissanu Meeyoo; Thirasak Rirksomboon; Johannes Schwank

    2007-01-01

    In this study,the effect of Nb loading on the catalytic activity of Ce0.75Zr0.25O2-supported Ni catalysts was studied for methane partial oxidation.The catalysts were characterized by BET,H2 chemisorption,XRD,TPR,TEM and tested for methane partial oxidation to syngas in the temperature range of 400-800 ℃ at atmospheric pressure.The results showed that the activity of methane partial oxidation on the catalysts was apparently dependent on Nb loading.It seemed that the addition of Nb lowered the catalytic activity for methane partial oxidation and increased the extent of carbon deposition.This might be due to the strong interaction between NiO and Nb-modified support and reduction of surfaceoxygen reducibility.

  5. 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...

  6. Recent Results on Fast Flow Gas-Phase Partial Oxidation of Lower Alkanes

    Institute of Scientific and Technical Information of China (English)

    Vladimir S. Arutyunov

    2004-01-01

    Recent experimental results and kinetic modeling of fast flow gas-phase oxidation of methane and other lower alkanes to methanol and other oxygenates are discussed, alongside with prospects and possible areas for applications of the processes.

  7. Autothermal Reforming and Partial Oxidation of Methane in Fluidized Reactor over Highly Dispersed Ni Catalyst Prepared from Ni Complex

    Institute of Scientific and Technical Information of China (English)

    GAO Jing; HOU Zhao-Yin; SHEN Kai; LOU Hui; FEI Jin-Hua; ZHENG Xiao-Ming

    2006-01-01

    Highly dispersed Ni catalysts on spherical SiO2 were prepared by simple impregnation of Ni(acac)2, [Ni-(NH3)6-n(H2O)n]2+, [Ni(en)3]2+ and [Ni(EDTA)]2-. Pulse adsorption of H2 and TEM analysis results confirmed that Ni was dispersed very well on the surface of SiO2 even after calcination (4 h) and reduction (1 h) at high temperature of 800 ℃. These highly dispersed and uniquely sized Ni crystallites were more stable and more reactive for both autothermal reforming and partial oxidation of methane in fluidized reactor.

  8. Oscillatory Behavior during the Catalytic Partial Oxidation of Methane: Following Dynamic Structural Changes of Palladium Using the QEXAFS Technique

    OpenAIRE

    Stoetzel, Jan; Frahm, Ronald; Kimmerle, Bertram; Nachtegaal, Maarten; Grunwaldt, Jan-Dierk

    2012-01-01

    Pd/Al2O3 catalysts oscillate between ignition and extinction of the catalytic partial oxidation of methane when they are exposed to a 2:1 reaction mixture of methane and oxygen. The oscillations of the catalytic performance and the structure of Pd/Al2O3 catalysts in a fixed-bed reactor were investigated using spatially and time-resolved in situ quick scanning X-ray absorption spectroscopy with online mass spectrometry. The dynamic methane conversion oscillated between an inactive state, where...

  9. Strategies for catalyst development: possibilities of the ``rational approach`` illustrated with partial oxidation reactions

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, W.; Schedel-Niedrig, T.; Schloegl, R. [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin (Germany). Abt. Oberflaechenphysik

    1998-12-31

    The paper discusses two petrochemical selective oxidation reactions namely the practised formation of styrene (STY) and the desired oxidative functionalisation of propane. The present knowledge about the mode of operation of oxide catalysts is critically considered. The dehydrogenation of ethylbenzene (EB) should be described by an oxidehydration with water acting as oxidant. The potential role of the coke formed during catalytic reaction as co-catalyst will be discussed. Selective oxidation is connected with the participation of lattice oxygen mechanism which transforms unselective gas phase oxygen into selective oxygen. The atomistic description of this process is still quite unclear as well as the electron structural properties of the activated oxygen atom. The Role of solid state acidity as compared to the role of lattice oxygen is much less well investigated modern multiphase-multielement oxide (MMO) catalysts. The rationale is that the significant efforts made to improve current MMO systems by chemical modifications can be very much more fruitful when in a first step the mode of action of a catalyst is clarified on the basis of suitable experiments. Such time-consuming experiments at the beginning of a campaign for catalyst improvement pay back their investment in later stages of the project when strategies of chemical development can be derived on grounds of understanding. (orig.)

  10. Magnetization and Mössbauer study of partially oxidized iron cluster films deposited on HOPG

    Science.gov (United States)

    Tarras-Wahlberg, Nils; Kamali, Saeed; Andersson, Mats; Johansson, Christer; Rosén, Arne

    2014-10-01

    Iron clusters produced in a laser vaporization source were deposited to form cluster-assembled thin films with different thicknesses on highly oriented pyrolytic graphite substrates. The development of oxidation of the clusters with time, up to three years, was investigated by magnetic measurements using an alternating gradient magnetometer. Furthermore, to receive information about the oxidation states, clusters of 57Fe were studied using Mössbauer spectroscopy. The magnetic analysis shows a time evolution of the saturation magnetization, remanence, and coercivity, determined from the hysteresis curves characteristic of a progressing oxidation. The different thicknesses of the iron cluster films as well as a protective layer of vanadium influence the magnetic properties when the samples are subjected to oxidation with time. While the saturation magnetization and remanence decrease and reach half the initial values for almost all the samples after three years, the coercivity increases for all samples and is more substantial for the thickest sample with a vanadium protective layer. This value is three folded after three years. Furthermore, based on a core-shell model and using the saturation magnetization values we have been able to quantitatively calculate the amount of the increase of Fe-oxide as a function of time. The Mössbauer spectroscopy shows peaks corresponding to iron metal and maghemite.

  11. Effect of oxygen partial pressure on microstructural and optical properties of titanium oxide thin films prepared by pulsed laser deposition

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Microstructural and optical properties are studied systematically. • The optical properties are studied by UV–visible and photoluminescence. • The PL spectra shows two peaks correspond to bandgap of anatase and rutile. • The maximum refractive index of 2.73 is obtained for rutile phase of titania. - Abstract: Nanocrystalline titanium oxide (TiO2) thin films were deposited on silicon (1 0 0) and quartz substrates at various oxygen partial pressures (1 × 10−5 to 3.5 × 10−1 mbar) with a substrate temperature of 973 K by pulsed laser deposition. The microstructural and optical properties were characterized using Grazing incidence X-ray diffraction, atomic force microscopy, UV–visible spectroscopy and photoluminescence. The X-ray diffraction studies indicated the formation of mixed phases (anatase and rutile) at higher oxygen partial pressures (3.5 × 10−2 to 3.5 × 10−1 mbar) and strong rutile phase at lower oxygen partial pressures (1 × 10−5 to 3.5 × 10−3 mbar). The atomic force microscopy studies showed the dense and uniform distribution of nanocrystallites. The root mean square surface roughness of the films increased with increasing oxygen partial pressures. The UV–visible studies showed that the bandgap of the films increased from 3.20 eV to 3.60 eV with the increase of oxygen partial pressures. The refractive index was found to decrease from 2.73 to 2.06 (at 550 nm) as the oxygen partial pressure increased from 1.5 × 10−4 mbar to 3.5 × 10−1 mbar. The photoluminescence peaks were fitted to Gaussian function and the bandgap was found to be in the range ∼3.28–3.40 eV for anatase and 2.98–3.13 eV for rutile phases with increasing oxygen partial pressure from 1 × 10−5 to 3.5 × 10−1 mbar

  12. Partial oxidation of methane to formaldehyde on Mo03, Fe203 and ferromolybdenum catalysts

    Directory of Open Access Journals (Sweden)

    José Daniel Del Río

    2010-04-01

    Full Text Available One of the main challenges for catalysis has been direct methane conversion to useful products such as methanol and formaldehyde. Formaldehyde is currently produced by a three-step industrial process with syngas and metha- nol as intermediate products. MoO , Fe O and Fe (MoO catalysts were used with four different Mo/Fe molar 3\t2 3 2 4 3 ratios (0.5, 1, 1.5, 2 in this work. The ferromolybdenum catalyst was prepared by coprecipitation. Pure oxides are more active; however they are not formaldehyde selective, but carbon oxide (CO, CO selective. The ferro- molybdenum catalysts showed better HCHO selectivity at low conversions; the molybdenum oxide content did not show increased in catalytic activity. Increased reaction temperature did not increase formaldehyde selectivity.

  13. Implication of the Acid-Base Properties of V/Ti-oxide Catalyst in Toluene Partial Oxidation

    OpenAIRE

    Kiwi-Minsker, Lioubov; Bulushev, Dmitri A.; Rainone, Fabio; Renken, Albert

    2002-01-01

    The work presents the effect of K-doping on V/Ti-oxides taking into account: the surface acid–base properties and the structure of surface vanadia species in respect to the catalyst performance and deactivation. The structure of active surface species determines redox properties, which are related to the catalytic performance by the Mars–van Krevelen mechanism. The reducibility of surface vanadia is studied by temperature-programmed reduction (TPR) in H2. The molecular structure of surface va...

  14. Silicon-technology based microreactors for high-temperature heterogeneous partial oxidation reactions

    NARCIS (Netherlands)

    Tiggelaar, Roald Michel

    2004-01-01

    In this thesis the results of a study into the feasibility of silicon-technology based microreactors for fast oxidation reactions have been discussed. When designed properly, silicon microreactors are suitable for studying heterogeneous gas phase reactions, such as reaction kinetics of direct cataly

  15. Oxidation behavior of V-Cr-Ti alloys in low-partial-pressure oxygen environments

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Uz, M. [Argonne National Lab., IL (United States)

    1998-09-01

    A test program is in progress at Argonne National Laboratory to evaluate the effect of pO{sub 2} in the exposure environment on oxygen uptake, scaling kinetics, and scale microstructure in V-Cr-Ti alloys. The data indicate that the oxidation process follows parabolic kinetics in all of the environments used in the present study. From the weight change data, parabolic rate constants were evaluated as a function of temperature and exposure environment. The temperature dependence of the parabolic rate constants was described by an Arrhenius relationship. Activation energy for the oxidation process was fairly constant in the oxygen pressure range of 1 {times} 10{sup {minus}6} to 1 {times} 10{sup {minus}1} torr for both the alloys. The activation energy for oxidation in air was significantly lower than in low-pO{sub 2} environments, and for oxidation in pure O{sub 2} at 760 torr was much lower than in low-pO{sub 2} environments. X-ray diffraction analysis of the specimens showed that VO{sub 2} was the dominant phase in low-pO{sub 2} environments, while V{sub 2}O{sub 5} was dominant in air and in pure oxygen at 76f0 torr.

  16. Synthesis of single-site copper catalysts for methane partial oxidation.

    Science.gov (United States)

    Grundner, S; Luo, W; Sanchez-Sanchez, M; Lercher, J A

    2016-02-11

    Cu-Exchanged zeolites are known as active materials for methane oxidation to methanol. However, understanding of the formation of Cu active species during synthesis, dehydration and activation is fragmented and rudimentary. We show here how a synthesis protocol guided by insight in the ion exchange elementary steps leads to highly uniform Cu species in mordenite (MOR). PMID:26744744

  17. Effect of the technology of implanting nitrogen into buried oxide on the radiation hardness of the top gate oxide for partially depleted SOI PMOSFET

    Institute of Scientific and Technical Information of China (English)

    Zheng Zhong-Shan; Liu Zhong-Li; Zhang Guo-Qiang; Li Ning; Fan Kai; Zhang En-Xia; Yi Wan-Bing; Chen Meng; Wang Xi

    2005-01-01

    The effect of implanting nitrogen into buried oxide on the top gate oxide hardness against total irradiation does has been investigated with three nitrogen implantation doses(8×1015,2×1016 and 1×1017cm -2) for partially depleted SOI PMOSFET.The experimental results reveal the trend of negative shift of the thershold voltages of the studied transistors with the incerase of nitrogen implantation dose before irradition. After the irradiation with a total dose of 5×105 rad (Si)under a positive gate voltage of 2V,the threshold voltage shift of the transistors corresponding to the nitrogen implantation dose 8×1015cm -2 is smaller than that of the transistors without implantation.However, when the implantation dose reaches 2×1016 and 1×1017cm-2, for the majority of the tested transistors,their top gate oxide was badly damaged due to irratiation. In addition, the radiation also causes damage to the body -drain junctions of thetransistors with the gate oxide damaged.All the results can be interpreted by tracing back to the nitrogen implantation damage to the crystal lattices in the top silicon.

  18. Mechanosynthesis and mechanochemical treatment of bismuth doped vanadium phosphorus oxide catalysts for the partial oxidation of n-butane to maleic anhydride

    Institute of Scientific and Technical Information of China (English)

    Y H.Taufiq-Yap; Y C.Wong; Y Kamiya; W.J.Tang

    2008-01-01

    Three Bi-doped vanadyl pyrophosphate catalysts were prepared via dihydrate route(VPD method),which consisted of different preparation methods including mechanosvnthesis,mechanochemical treatment,and the conventional reflux method.The catalysts produced by the above three methods were characterized by x-ray diffraction(XRD),scanning electron microscopy(SEM),and temperature programmed reduction(TPR).Catalytic evaluation for the partial oxidation of n-butane to maleic anhydride (MA) was also carried out.The XRD patterns of all the Bi-doped catalysts showed the main peaks of pyrophosphate phase.Lower intensity peaks were observed for the mechanochemically treated Bi-doped catalyst(VPDBiMill)with two additional small DeakS corresponding to the presence of a small amount of V5+ phase.The TPR profiles showed that the highest amount of active oxygen species.i.e.V4+-O- pair,responsible for n-butane activation,was removed from VPDBiMill.Furthermore.from the catalytic test results.the graph of selectivity to MA as a function of the conversion of n-butane demonstrated that VPDBiMill was the most selective catalyst.This suggests that the mechanochemical treatment of vanadium phosphate catalyst(VPDBiMill)is a potential method to improve the catalytic properties for the partial oxidation of n-butane to maleic anhydride.

  19. Emissions of nitrogen oxides from partially premixed flames stabilized on a conical bluff body

    OpenAIRE

    Dutka, Marcin Damian

    2015-01-01

    Carbon capture and storage (CCS) technologies allow for the reduction of carbon dioxide (CO2) emissions from the combustion sources of fossil fuels. One such technology is based on the use of hydrogen or hydrogen-enriched fuels and allows for a significant reduction of CO2 emissions. All regulated pollutant emissions, except for harmful nitrogen oxides (NOx), can also be reduced using hydrogen. Hydrogen’s unique properties are challenging for burner designers. High hydrogen-air...

  20. Oxidation of X20 in Water Vapour: The Effect of Temperature and Oxygen Partial Pressure

    DEFF Research Database (Denmark)

    Hansson, Anette Nørgaard; Montgomery, Melanie; Somers, Marcel A. J.

    2009-01-01

    The oxidation behaviour of X20 in various mixtures of water, oxygen and hydrogen was investigated at temperatures between 500 C and 700 C (time: 336 h). The samples were characterised using reflected light microscopy and scanning electron microscopy equipped with energy dispersive spectroscopy...... are discussed based on the various hypotheses of the accelerating effect of water vapour that have been put forth in the literature....

  1. Catalytic oxidation of cyclohexanone to adipic acid catalysed by supported phosphotungstic acid%固载磷钨酸催化氧化环己酮合成己二酸

    Institute of Scientific and Technical Information of China (English)

    叶天旭; 马雪妮; 刘京燕

    2009-01-01

    Adipic acid was synthesized via oxidation of cyclohexanone using phosphotungstic acid (H3PW12O40)/Al2O3 as the catalyst and 30% H2O2 as the oxidant. The influence of reaction condition on the yield of adipic acid was investigated. The optimum reaction condition was obtained as follows: n (hydrogen peroxide): n (phosphoric acid ): n (cyclohexanone)=4.4:0.99:1 ,n( phosphotungstic acid):n(cyclohexanone) =1:290, reaction at 75℃ for 1 h and then at 93℃ for7 h. Adipic acid yield of 95.5% was attained using with phosphoric acid as the promoter. Strength of the supported catalyst was enhanced by introduction of lanthanum.%以氧化铝固载的磷钨酸为催化剂,30%过氧化氢为氧化剂,催化氧化环己酮合成己二酸.考察反应条件对己二酸收率的影响,得到最佳工艺条件:n(过氧化氢)∶n(磷酸)∶n(环己酮)=4.4∶0.99∶1,n(磷钨酸)∶n(环己酮)=1∶290,75℃反应1 h,再于93℃反应7 h,加入磷酸助剂,己二酸收率达95.5%.采用镧改性氧化铝固载磷钨酸,固载强度高.

  2. Effect of different mixing ways in palladium/ceria-zirconia/alumina preparation on partial oxidation of methane

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qingwei; WEN Jing; SHEN Meiqing; WANG Jun

    2008-01-01

    The effect of the mixing ways of Ce0.7Zr0.3O2-Al2O3 mixed oxides on the partial oxidations of methane (POM) was investigated over Pd/Ce0.7Zr0.3O2-Al2O3 catalysts, the mixing ways including salt precursor mixing (ATOM), precipitator mixing (MOL), and powder mechanically mixing (MECH), respectively. The test results indicated that among the three samples, Pd/ATOM had the best catalytic activity,while Pd/MOL had the best stability in the stability test. Both the activity sequences of the fresh and used samples were consistent with the order of Pd dispersion. According to the X-ray diffraction (XRD) and BET characterization, the interaction of Ce4+, Zr4+, and Al3+ in the ATOM mixed oxide was in favor of performing higher catalytic activity and thermal stability. The stability test indicated that Pd/MOL had the highest Pd dispersion and least coke formation on the active sites calculated by the H2-chemisorption and TG results, which was consid-ered to relate to its superior activity of POM to other catalysts.

  3. Quercetin Partially Preserves Development of Osteoblast Phenotype in Fetal Rat Calvaria Cells in an Oxidative Stress Environment.

    Science.gov (United States)

    Messer, Jonathan G; La, Stephanie; Hopkins, Robin G; Kipp, Deborah E

    2016-12-01

    Studies are needed to improve understanding of the osteoblast antioxidant response, and the balance between oxidative homeostasis and osteoblast differentiation. The flavonol quercetin aglycone (QRC) up-regulates the osteoblast antioxidant response in vitro without suppressing osteoblast phenotype, suggesting that QRC may preserve osteoblast phenotypic development in cells subsequently exposed to oxidative stress, which suppresses osteoblast differentiation. The aims of this study were to assess the extent that QRC pretreatment preserved development of the osteoblast phenotype in cells subsequently cultured with hydrogen peroxide, an oxidative stressor, and to characterize alterations in the osteoblast antioxidant response and in key antioxidant signaling pathways. We hypothesized that pretreatment with QRC would preserve phenotypic development after hydrogen peroxide treatment, suppress the hydrogen peroxide-induced antioxidant response, and that the antioxidant response would involve alterations in Nrf2 and ERK1/2 signaling. Results showed that treating fetal rat calvarial osteoblasts for 4 days (D5-9) with 300 μM hydrogen peroxide resulted in fewer alkaline phosphatase-positive cells and mineralized nodules, altered cell morphology, and significantly lower osteoblast phenotypic gene expression (P stress response coincided with alterations in phosphorylated ERK1/2, but not Nrf2. These results suggest that QRC suppresses hydrogen peroxide-induced activation of the antioxidant response, and partially preserves osteoblast phenotypic development. J. Cell. Physiol. 231: 2779-2788, 2016. © 2016 Wiley Periodicals, Inc. PMID:27028516

  4. Melatonin attenuates hypertension-induced renal injury partially through inhibiting oxidative stress in rats.

    Science.gov (United States)

    Qiao, Yu-Feng; Guo, Wen-Juan; Li, Lu; Shao, Shan; Qiao, Xi; Shao, Jin-Jin; Zhang, Qiong; Li, Rong-Shan; Wang, Li-Hua

    2016-01-01

    The aim of the present study was to investigate the protective effects of melatonin (MLT) on hypertension-induced renal injury and identify its mechanism of action. Twenty-four healthy male Wistar rats were divided into a sham control group (n=8), which was subjected to sham operation and received vehicle treatment (physiological saline intraperitoneally at 0.1 ml/100 g), a vehicle group (n=8), which was subjected to occlusion of the left renal artery and vehicle treatment, and the MLT group (n=8), which was subjected to occlusion of the left renal artery and treated with MLT (10 mg/kg/day). Pathological features of the renal tissues were determined using hematoxylin and eosin staining and Masson staining. Urine protein, serum creatinine (Scr), superoxide dismutase (SOD) and malondialdehyde (MDA) were determined. Immunohistochemical analysis was performed to determine the expression of heme oxygenase‑1 (HO‑1), intercellular adhesion molecule‑1 (ICAM‑1), inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS). Furthermore, reverse transcription polymerase chain reaction was conducted to determine the mRNA expression of HO‑1, ICAM‑1, eNOS and iNOS. A marked decrease in blood pressure was noticed in the MLT group at week 4 compared with that of the vehicle group (Ptreatment attenuated the infiltration of inflammatory cells and oedema/atrophy of renal tubules. MLT attenuated hypertension-induced increases in urine protein excretion, serum creatinine and MDA as well as decreases in SOD activity in renal tissues. Furthermore, MLT attenuated hypertension-induced increases in iNOS and ICAM‑1 as well as decreases in eNOS and HO‑1 expression at the mRNA and protein level. In conclusion, the results of the present study indicated that MLT had protective roles in hypertension‑induced renal injury. Its mechanism of action is, at least in part, associated with the inhibition of oxidative stress. PMID:26531807

  5. Iron-catalysed tritiation of pharmaceuticals

    Science.gov (United States)

    Pony Yu, Renyuan; Hesk, David; Rivera, Nelo; Pelczer, István; Chirik, Paul J.

    2016-01-01

    A thorough understanding of the pharmacokinetic and pharmacodynamic properties of a drug in animal models is a critical component of drug discovery and development. Such studies are performed in vivo and in vitro at various stages of the development process—ranging from preclinical absorption, distribution, metabolism and excretion (ADME) studies to late-stage human clinical trials—to elucidate a drug molecule’s metabolic profile and to assess its toxicity. Radiolabelled compounds, typically those that contain 14C or 3H isotopes, are one of the most powerful and widely deployed diagnostics for these studies. The introduction of radiolabels using synthetic chemistry enables the direct tracing of the drug molecule without substantially altering its structure or function. The ubiquity of C-H bonds in drugs and the relative ease and low cost associated with tritium (3H) make it an ideal radioisotope with which to conduct ADME studies early in the drug development process. Here we describe an iron-catalysed method for the direct 3H labelling of pharmaceuticals by hydrogen isotope exchange, using tritium gas as the source of the radioisotope. The site selectivity of the iron catalyst is orthogonal to currently used iridium catalysts and allows isotopic labelling of complementary positions in drug molecules, providing a new diagnostic tool in drug development.

  6. The uptake and excretion of partially oxidized sulfur expands the repertoire of energy resources metabolized by hydrothermal vent symbioses.

    Science.gov (United States)

    Beinart, R A; Gartman, A; Sanders, J G; Luther, G W; Girguis, P R

    2015-05-01

    Symbiotic associations between animals and chemoautotrophic bacteria crowd around hydrothermal vents. In these associations, symbiotic bacteria use chemical reductants from venting fluid for the energy to support autotrophy, providing primary nutrition for the host. At vents along the Eastern Lau Spreading Center, the partially oxidized sulfur compounds (POSCs) thiosulfate and polysulfide have been detected in and around animal communities but away from venting fluid. The use of POSCs for autotrophy, as an alternative to the chemical substrates in venting fluid, could mitigate competition in these communities. To determine whether ESLC symbioses could use thiosulfate to support carbon fixation or produce POSCs during sulfide oxidation, we used high-pressure, flow-through incubations to assess the productivity of three symbiotic mollusc genera-the snails Alviniconcha spp. and Ifremeria nautilei, and the mussel Bathymodiolus brevior-when oxidizing sulfide and thiosulfate. Via the incorporation of isotopically labelled inorganic carbon, we found that the symbionts of all three genera supported autotrophy while oxidizing both sulfide and thiosulfate, though at different rates. Additionally, by concurrently measuring their effect on sulfur compounds in the aquaria with voltammetric microelectrodes, we showed that these symbioses excreted POSCs under highly sulfidic conditions, illustrating that these symbioses could represent a source for POSCs in their habitat. Furthermore, we revealed spatial disparity in the rates of carbon fixation among the animals in our incubations, which might have implications for the variability of productivity in situ. Together, these results re-shape our thinking about sulfur cycling and productivity by vent symbioses, demonstrating that thiosulfate may be an ecologically important energy source for vent symbioses and that they also likely impact the local geochemical regime through the excretion of POSCs.

  7. Rare earth oxide-doped titania nanocomposites with enhanced photocatalytic activity towards the degradation of partially hydrolysis polyacrylamide

    Science.gov (United States)

    Li, Jinhuan; Yang, Xia; Yu, Xiaodan; Xu, Leilei; Kang, Wanli; Yan, Wenhua; Gao, Hongfeng; Liu, Zhonghe; Guo, Yihang

    2009-01-01

    Rare-earth oxide-doped titania nanocomposites (RE 3+/TiO 2, where RE = Eu 3+, Pr 3+, Gd 3+, Nd 3+, and Y 3+) were prepared by a one-step sol-gel-solvothermal method. The products exhibited anatase phase structure, mesoporosity, and interesting surface compositions with three oxygen species and two titanium species. The products were used as the photocatalysts to degrade a partially hydrolysis polyacrylamide (HPAM) under UV-light irradiation, a very useful polymer in oil recovery. For comparison, Degussa P25 and as-prepared pure TiO 2 were also tested under the same conditions. The enhanced photocatalytic activity was obtained on as-prepared Eu 3+ (Gd 3+, Pr 3+)/TiO 2 composites, and the reasons were explained. Finally, the degradation pathway of HPAM over the RE 3+/TiO 2 composite was put forward based on the intermediates produced during the photocatalysis procedure.

  8. An experimental study of the partial oxidation of ethane to ethylene in a shallow fluidized bed reactor

    Directory of Open Access Journals (Sweden)

    DANICA BRZIC

    2007-02-01

    Full Text Available The partial catalytic oxidation of ethane to ethylene was investigated experimentally in a shallow fluidized bed. The performaces of two catalyst types, pure g‑Al2O3 and V2O5/ g-Al2O3 particles 1.8 mm in diameter, were analyzed. A pilot fluidized bed reactor with rectangular cross-section of 100mm´100mm was used. The experiments were carried out under atmospheric pressure in a dilute system under oxygen excess conditions. V2O5/g-Al2O3 showed good catalytic performances regarding ethylene selectivity. The influence of the temperature (in the range of 400–600 °C and the contact time (in the range of 35 – 85 kg sm-3 on the conversion of ethane and the selectivity to ethylene was analyzed. The highest yield of ethylene was 18 %.

  9. Partial Oxidation of Methane to Synthesis Gas over Hexaaluminates LaMAl11O19-δ catalysts

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A series of M-substituted hexaaluminates LaMAl11O19-δ (M=Fe, Co, Ni, Mn, and Cu)were prepared and characterized by XRD, XPS, TPR and TGA techniques, respectively. They exhibited different reducibility and catalytic activity for partial oxidation of methane (POM) to synthesis gas. Among the LaMAl11O19-δ samples, LaNiAl11O19-δ showed the best catalytic activity for the topic reaction and selectivity for synthesis gas at 780 ℃ for 2 h. The conversion of CH4 was over 99.2%, and the product selectivity for both CO and H2 was above 90.3%.

  10. Nitrous oxide production pathways in a partial nitritation-anammox reactor: Isotopic evidence for nitrous oxide production associated anaerobic ammonium oxidation?

    Science.gov (United States)

    Wunderlin, P.; Harris, E. J.; Joss, A.; Emmenegger, L.; Kipf, M.; Mohn, J.; Siegrist, H.

    2014-12-01

    Nitrous oxide (N2O) is a strong greenhouse gas and a major sink for stratospheric ozone. In biological wastewater treatment N2O can be produced via several pathways. This study investigates the dynamics of N2O emissions from a nitritation-anammox reactor, and links its interpretation to the nitrogen and oxygen isotopic signature of the emitted N2O. A 400-litre single-stage nitritation-anammox reactor was operated and continuously fed with digester liquid. The isotopic composition of N2O emissions was monitored online with quantum cascade laser absorption spectroscopy (QCLAS; Aerodyne Research, Inc.; Waechter et al., 2008). Dissolved ammonium and nitrate were monitored online (ISEmax, Endress + Hauser), while nitrite was measured with test strips (Nitrite-test 0-24mgN/l, Merck). Table 1. Summary of experiments conducted to understand N2O emissions Experimental conditions O2[mgO2/L] NO2-[mgN/L] NH4+[mgN/L] N2O/NH4+[%] Normal operation <0.1 <0.5 10 0.6 Normal operation, high NH4+ <0.1 <0.5 100 6.1 High aeration 0.5 to 1.5 up to 50 10 and 50 4.9 NO2- addition (oxic) <0.1 <0.5 to 4 10 5.8 NO2- addition (anoxic) 0 <0.5 to 4 10 3.2 NH2OH addition <0.1 <0.5 10 2.5 Results showed that under normal operating conditions, the N2O isotopic site preference (SP = d15Nα - d15Nβ) was much higher than expected - up to 41‰ - strongly suggesting an unknown N2O production pathway, which is hypothesized to be mediated by anammox activity (Figure 1). A less likely explanation is that the SP of N2O was increased by partial N2O reduction by heterotrophic denitrification. Various experiments were conducted to further investigate N2O formation pathways in the reactor. Our data reveal that N2O emissions increased when reactor operation was not ideal, for example when dissolved oxygen was too high (Table 1). SP measurements confirmed that these N2O peaks were due to enhanced nitrifier denitrification, generally related to nitrite build-up in the reactor (Figure 1; Table 1). Overall

  11. Reaction phenomena of catalytic partial oxidation of methane under the impact of carbon dioxide addition and heat recirculation

    International Nuclear Information System (INIS)

    The reaction phenomena of CPOM (catalytic partial oxidation of methane) in a Swiss-roll reactor are studied numerically where a rhodium-based catalyst bed is embedded at the center of the reactor. CO2 is added into the feed gas and excess enthalpy recovery is performed to evaluate their influences on CPOM performance. In the study, the mole ratio of O2 to CH4 (O2/CH4 ratio) is fixed at 0.5 and the mole ratio of CO2 to O2 (CO2/O2 ratio) is in the range of 0–2. The results reveal that CO2 addition into the influent has a slight effect on methane combustion, but significantly enhances dry reforming and suppresses steam reforming. The reaction extents of steam reforming and dry reforming in CPOM without heat recovery and CO2 addition are in a comparable state. Once CO2 is added into the feed gas, the dry reforming is enhanced, thereby dominating CH4 consumption. Compared to the reactor without excess enthalpy recovery, heat recirculation drastically increases the maximum reaction temperature and CH4 conversion in the catalyst bed; it also intensifies the H2 selectivity, H2 yield, CO2 conversion, and syngas production rate. The predictions indicate that the heat recirculation is able to improve the syngas formation up to 45%. - Highlights: • Catalytic partial oxidation of methane with CO2 addition and heat recovery is studied. • CO2 addition has a slight effect on methane combustion. • CO2 addition significantly enhances dry reforming and suppresses steam reforming. • Dry reforming dominates CH4 consumption when CO2 addition is large. • Heat recirculation can improve the syngas formation up to 45%

  12. Study of the dynamics of the MoO2-Mo2C system for catalytic partial oxidation reactions

    Science.gov (United States)

    Cuba Torres, Christian Martin

    On a global scale, the energy demand is largely supplied by the combustion of non-renewable fossil fuels. However, their rapid depletion coupled with environmental and sustainability concerns are the main drivers to seek for alternative energetic strategies. To this end, the sustainable generation of hydrogen from renewable resources such as biodiesel would represent an attractive alternative solution to fossil fuels. Furthermore, hydrogen's lower environmental impact and greater independence from foreign control make it a strong contender for solving this global problem. Among a wide variety of methods for hydrogen production, the catalytic partial oxidation offers numerous advantages for compact and mobile fuel processing systems. For this reaction, the present work explores the versatility of the Mo--O--C catalytic system under different synthesis methods and reforming conditions using methyl oleate as a surrogate biodiesel. MoO2 exhibits good catalytic activity and exhibits high coke-resistance even under reforming conditions where long-chain oxygenated compounds are prone to form coke. Moreover, the lattice oxygen present in MoO2 promotes the Mars-Van Krevelen mechanism. Also, it is introduced a novel beta-Mo2C synthesis by the in-situ formation method that does not utilize external H2 inputs. Herein, the MoO 2/Mo2C system maintains high catalytic activity for partial oxidation while the lattice oxygen serves as a carbon buffer for preventing coke formation. This unique feature allows for longer operation reforming times despite slightly lower catalytic activity compared to the catalysts prepared by the traditional temperature-programmed reaction method. Moreover, it is demonstrated by a pulse reaction technique that during the phase transformation of MoO2 to beta-Mo2C, the formation of Mo metal as an intermediate is not responsible for the sintering of the material wrongly assumed by the temperature-programmed method.

  13. Hydrogen production by partial oxidation of methanol over gold catalysts supported on TiO{sub 2}-MO{sub x} (M=Fe, Co, Zn) composite oxides

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Feg-Wen; Yu, Hsin-Yin; Roselin, L. Selva; Yang, Hsien-Chang; Ou, Ti-Cheng [Department of Chemical and Materials Engineering, National Central University, Chungli 32001 (Taiwan)

    2006-04-11

    Hydrogen production by partial oxidation of methanol (POM) has been investigated over Au/TiO{sub 2}-MO{sub x} (M=Fe, Co and Zn) catalysts in the temperature range of 423-548K. The catalysts were characterized by ICP, BET, XRD, TEM and XPS analyses. The XRD analysis confirms the desired structure and phase purity of Fe{sub 2}O{sub 3}, Co{sub 3}O{sub 4}, ZnO and TiO{sub 2} samples and the presence of gold in these materials. TEM observations show that the gold particles are stabilized against sintering during calcination and after catalytic tests, in the presence of MO{sub x} in Au/TiO{sub 2} catalysts. The XPS analysis detects the existence of metallic gold (Au{sup 0}), non-metallic gold (Au{sup {delta}}{sup +}) and Au{sub 2}O{sub 3} species in the uncalcined catalyst samples both before and after reaction, and the existence of metallic gold (Au{sup 0}) and Au{sub 2}O{sub 3} species in the calcined catalyst samples. The catalytic activity of Au/TiO{sub 2} for the POM reaction to produce hydrogen is improved by using additional support (MO{sub x}), probably due to a combination of factors, such as increasing the mobility of the lattice oxygen, maintaining the adequate oxidation state of the active gold particles and controlling the sintering of gold particles. Therefore, MO{sub x} can act as a structural promoter and/or as a cocatalyst. The most active catalyst is Au/TiO{sub 2}-Fe{sub 2}O{sub 3}. Although Fe{sub 2}O{sub 3} in Au/TiO{sub 2} catalysts increases the catalytic activity, a surfeit of Fe{sub 2}O{sub 3} lowers the activity for hydrogen formation. Calcination of the catalyst samples results in a decrease of the catalytic activity. The sample dried at 373K in air exhibits the highest activity for POM reaction. Both methanol conversion and hydrogen selectivity are increased with increase in reaction temperature. The reaction pathway is suggested to consist of consecutive methanol combustion, partial oxidation, steam reforming and decomposition. CO produced by

  14. The gas chromatographic analysis of the reaction products of the partial isobutane oxidation as a two phase process.

    Science.gov (United States)

    Willms, Thomas; Kryk, Holger; Hampel, Uwe

    2016-08-01

    The partial oxidation of isobutane to t-butyl hydroperoxide (TBHP) has been studied analytically for the first time as a two-phase process in a capillary micro reactor. In order to obtain detailed information on products, yields, selectivities and reaction pathways, the products have been investigated by GC/MS. An Rxi-5ms column and a PTV-injector have been used to analyze the liquid products. TBHP, di-t-butyl peroxide (DTBP), t-butanol (TBA), and propanone as main products as well as further by-products e.g. methanal, isopropanol, isobutanol and isobutanal in minor quantities have been identified by MS. The liquid products have been obtained by quenching the reaction and vaporizing the isobutane afterwards by pressure reduction using a mass flow controller allowing a constant mass flow. For all liquid reaction products calibrations, a validation of the method including limits of quantification and detection as well as calculation of uncertainties has been performed. The results have been applied successfully for the investigation of the selectivities of the main products (TBHP, DTBP, TBA, propanone) of the isobutane oxidation. In the frame of the analytical investigation of this reaction a correlation coefficient of r(2)>0.999 for TBHP and DTBP, which is necessary to perform a validation, has been obtained for the first time. The gaseous phase has been analyzed using a GASPRO column, a DEANS switch, a mole sieve column and a TCD detector. Apart from the gaseous reactants, isobutene has been found. PMID:27378248

  15. Antibacterial Activity of Partially Oxidized Ag/Au Nanoparticles against the Oral Pathogen Porphyromonas gingivalis W83

    Directory of Open Access Journals (Sweden)

    Megan S. Holden

    2016-01-01

    Full Text Available Advances in nanotechnology provide opportunities for the prevention and treatment of periodontal disease. While physicochemical properties of Ag containing nanoparticles (NPs are known to influence the magnitude of their toxicity, it is thought that nanosilver can be made less toxic to eukaryotes by passivation of the NPs with a benign metal. Moreover, the addition of other noble metals to silver nanoparticles, in the alloy formulation, is known to alter the silver dissolution behavior. Thus, we synthesized glutathione capped Ag/Au alloy bimetallic nanoparticles (NPs via the galvanic replacement reaction between maltose coated Ag NPs and chloroauric acid (HAuCl4 in 5% aqueous triblock F127 copolymer solution. We then compared the antibacterial activity of the Ag/Au NPs to pure Ag NPs on Porphyromonas gingivalis W83, a key pathogen in the development of periodontal disease. Only partially oxidized glutathione capped Ag and Ag/Au (Au : Ag ≈ 0.2 NPs inhibited the planktonic growth of P. gingivalis W83. This effect was enhanced in the presence of hydrogen peroxide, which simulates the oxidative stress environment in the periodontal pocket during chronic inflammation.

  16. Partial oxidation of methane to syngas on Rh/Al{sub 2}O{sub 3} and Rh/Ce-ZrO{sub 2} catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Raquel L.; Bitencourt, Isabela G.; Passos, Fabio B., E-mail: fbpassos@vm.uff.br [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Dept. de Engenharia Quimica e Petroleo

    2013-01-15

    The partial oxidation of methane with {gamma}-Al{sub 2}O{sub 3}-, CeO{sub 2}-, ZrO{sub 2}- and Ce-ZrO{sub 2}-supported rhodium catalysts was investigated. DRIFTS (diffuse reflectance infrared spectroscopy) measurements of adsorbed CO showed the formation of different rhodium species on different supports, which influenced the dispersion of the metal. The effects of the metal dispersion, oxygen storage capacity on the activity of these catalysts for the partial oxidation of methane are discussed. (author)

  17. Effect of substrate temperature and oxygen partial pressure on microstructure and optical properties of pulsed laser deposited yttrium oxide thin films

    International Nuclear Information System (INIS)

    Yttrium oxide thin films were deposited on Si (1 1 1) and quartz substrates by pulsed laser deposition technique at different substrate temperature and oxygen partial pressure. XRD analysis shows that crystallite size of the yttrium oxide thin films increases as the substrate temperature increases from 300 to 873 K. However the films deposited at constant substrate temperature with variable oxygen partial pressure show opposite effect on the crystallite size. Band gap energies determined from UV-visible spectroscopy indicated higher values than that of the reported bulk value.

  18. Promoting effect of Co addition on the catalytic partial oxidation of methane at short contact time over a Rh/MgO catalyst

    OpenAIRE

    Naito, Seiji; Tanaka, Hisanori; Kado, Shigeru; Miyao, Toshihiro; Naito, Shuichi; Okumura, Kazu; Kunimori, Kimio; Tomishige, Keiichi

    2008-01-01

    In catalytic partial oxidation of methane under isothermal conditions, a 0.3 wt% Rh/MgO catalyst modified with Co at a molar ratio of Co/Rh = 1 gave greater CH4 conversion and selectivity to CO and H2 than unmodified 0.3 wt% Rh/MgO. Characterization results using temperature-programmed reduction, extended X-ray absorption fine structure, and transmission electron microscopy demonstrated alloy formation between Rh and Co. In catalytic partial oxidation of methane without N2 dilution, the Rh–Co...

  19. Lycium barbarum (wolfberry reduces secondary degeneration and oxidative stress, and inhibits JNK pathway in retina after partial optic nerve transection.

    Directory of Open Access Journals (Sweden)

    Hongying Li

    Full Text Available Our group has shown that the polysaccharides extracted from Lycium barbarum (LBP are neuroprotective for retinal ganglion cells (RGCs in different animal models. Protecting RGCs from secondary degeneration is a promising direction for therapy in glaucoma management. The complete optic nerve transection (CONT model can be used to study primary degeneration of RGCs, while the partial optic nerve transection (PONT model can be used to study secondary degeneration of RGCs because primary degeneration of RGCs and secondary degeneration can be separated in location in the same retina in this model; in other situations, these types of degeneration can be difficult to distinguish. In order to examine which kind of degeneration LBP could delay, both CONT and PONT models were used in this study. Rats were fed with LBP or vehicle daily from 7 days before surgery until sacrifice at different time-points and the surviving numbers of RGCs were evaluated. The expression of several proteins related to inflammation, oxidative stress, and the c-jun N-terminal kinase (JNK pathways were detected with Western-blot analysis. LBP did not delay primary degeneration of RGCs after either CONT or PONT, but it did delay secondary degeneration of RGCs after PONT. We found that LBP appeared to exert these protective effects by inhibiting oxidative stress and the JNK/c-jun pathway and by transiently increasing production of insulin-like growth factor-1 (IGF-1. This study suggests that LBP can delay secondary degeneration of RGCs and this effect may be linked to inhibition of oxidative stress and the JNK/c-jun pathway in the retina.

  20. Estudo da oxidação parcial do etanol em catalisadores de Rh por DRIFTS A DRIFTS study of the partial oxidation of ethanol on Rh catalysts

    Directory of Open Access Journals (Sweden)

    Raquel Lima Oliveira

    2013-01-01

    Full Text Available The partial oxidation of ethanol on γ-Al2O3, CeO2, ZrO2 and Ce xZr1-xO2 supported rhodium catalysts was investigated by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS. The catalysts were characterized by temperature-programmed reduction (TPR and cyclohexane dehydrogenation. DRIFTS studies on the partial oxidation of ethanol showed that ethanol is adsorbed dissociatively, through O-H bond breaking, with the formation of ethoxy species, followed by successive dehydrogenation to acetaldehyde and acetyl species. Further oxidation to acetate and carbonate species lead to the formation of CO, CH4 and H2 by decomposition. The presence of CeO2 in the catalysts favored the oxidation steps due to its oxygen storage capacity.

  1. A DRIFTS study of the partial oxidation of ethanol on Rh catalysts; Estudo da oxidacao parcial do etanol em catalisadores de Rh por DRIFTS

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Raquel Lima; Passos, Fabio Barboza, E-mail: fbpassos@vm.uff.br [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Departamento de Engenharia Quimica e de Petroleo

    2013-09-01

    The partial oxidation of ethanol on {gamma}-Al{sub 2}O{sub 3}, CeO{sub 2}, ZrO{sub 2} and Ce{sub x}Zr{sub 1-x}O{sub 2} supported rhodium catalysts was investigated by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). The catalysts were characterized by temperature-programmed reduction (TPR) and cyclohexane dehydrogenation. DRIFTS studies on the partial oxidation of ethanol showed that ethanol is adsorbed dissociatively, through O-H bond breaking, with the formation of ethoxy species, followed by successive dehydrogenation to acetaldehyde and acetyl species. Further oxidation to acetate and carbonate species lead to the formation of CO, CH{sub 4} and H{sub 2} by decomposition. The presence of CeO{sub 2} in the catalysts favored the oxidation steps due to its oxygen storage capacity. (author)

  2. Preparation and tumor cell model based biobehavioral evaluation of the nanocarrier system using partially reduced graphene oxide functionalized by surfactant

    Directory of Open Access Journals (Sweden)

    Wang Y

    2015-07-01

    Full Text Available Yimin Wang,1 Kunping Liu,1,2 Zewei Luo,1 Yixiang Duan1 1Research Center of Analytical Instrumentation, Key Laboratory of Bio-resource and Eco-environment, Ministry of Education, College of Life Science, Sichuan University, 2Faculty of Biotechnology Industry, Chengdu University, Chengdu, People’s Republic of China Background: Currently, surfactant-functionalized nanomaterials are tending toward development of novel tumor-targeted drug carriers to overcome multidrug resistance in cancer therapy. Now, investigating the biocompatibility and uptake mechanism of specific drug delivery systems is a growing trend, but usually a troublesome issue, in simple pharmaceutical research.Methods: We first reported the partially reduced graphene oxide modified with poly(sodium 4-styrenesulfonate (PSS as a nanocarrier system. Then, the nanocarrier was characterized by atomic force microscope, scanning electron microscope, high-resolution transmission electron microscope, ultraviolet–visible (UV-vis spectroscopy, Fourier transform infrared spectroscopy, X-Ray powder diffraction, and Raman spectroscopy. Epirubicin (EPI was attached to PSSG via π–π stacking, hydrogen bonding, and physical absorption to form conjugates of PSSG–EPI. The adsorption and desorption profiles, cytotoxicity coupled with drug accumulation, and uptake of PSSG and PSSG–EPI were evaluated. Finally, the subcellular behaviors, distribution, and biological fate of the drug delivery system were explored by confocal laser scanning microscope using direct fluorescence colocalization imaging and transmission electron microscopy.Results: The partially reduced graphene oxide sheets functionalized by surfactant exhibit good dispersibility. Moreover, due to much less carboxyl groups retained on the edge of PSSG sheets, the nanocarriers exhibit biocompatibility in vitro. The obtained PSSG shows a high drug-loading capacity of 2.22 mg/mg. The complexes of PSSG–EPI can be transferred to

  3. On the phase formation of titanium oxide thin films deposited by reactive DC magnetron sputtering: influence of oxygen partial pressure and nitrogen doping

    Science.gov (United States)

    Pandian, Ramanathaswamy; Natarajan, Gomathi; Rajagopalan, S.; Kamruddin, M.; Tyagi, A. K.

    2014-09-01

    This work describes about the control on phase formation in titanium oxide thin films deposited by reactive dc magnetron sputtering. Various phases of titanium oxide thin films were deposited by controlling the oxygen partial pressure during the sputtering process. By adding nitrogen gas to sputter gas mixture of oxygen and argon, the oxygen partial pressure was decreased further below the usual critical value, below and above which the sputtering yields metallic and oxide films, respectively. Furthermore, nitrogen addition eliminated the typical hysteretic behaviour between the flow rate and oxygen partial pressure, and significantly influenced the sputter rate. On increasing the oxygen partial pressure, the ratio between anatase and rutile fraction and grain size increases. The fracture cross-sectional scanning electron microscopy together with the complementary information from X-ray diffraction and micro-Raman investigations revealed the evolution and spatial distribution of the anatase and rutile phases. Both the energy delivered to the growing film and oxygen vacancy concentrations are correlated with the formation of various phases upon varying the oxygen partial pressure.

  4. The Oxidative Coupling of 2,6-Xylenol Catalyzed by Polymeric Complexes of Copper, 2. Physicochemical Study on Copper(II) Complexes of Partially Dimethylaminomethylated Polystyrene

    NARCIS (Netherlands)

    Schouten, Arend Jan; Wiedijk, Dick; Challa, Ger; Borkent, J.

    1977-01-01

    The polymeric catalyst formed by complexation of copper(II) chloride and partially dimethylaminomethylated polystyrene was investigated to explain its behaviour in the oxidative coupling of 2,6-xylenol. Viscometric studies indicated that at low polymer concentrations coordination of tertiary amine g

  5. Effect of Mass-Transport Limitations on the Performance of a Packed Bed Membrane Reactor for Partial Oxidations. Transport from the Membrane to the Packed Bed

    NARCIS (Netherlands)

    Sint Annaland, van M.; Kürten, U.; Kuipers, J.A.M.

    2007-01-01

    With a packed bed membrane reactor, the product yield can be significantly enhanced for partial oxidation systems, via distributive addition of oxygen to the reaction mixture along the axial coordinate of the reactor, provided that the reaction order in oxygen of the formation rate of the target pro

  6. 甲烷部分氧化制乙炔过程研究%A Study of Acetylene Production by Methane Flaming in a Partial Oxidation Reactor

    Institute of Scientific and Technical Information of China (English)

    刘业飞; 王铁峰; 李庆勋; 王德峥

    2011-01-01

    The partial oxidation of hydrocarbons is an important technical route to produce acetylene for chemical industry. The partial oxidation reactor is the key to high acetylene yields. This work is an experimental and numerical study on the use of a methane flame to produce acetylene. A lab scale partial oxidation reactor was used to produce ultra fuel-rich premixed jet flames. The axial temperature and species concentration profiles were measured for different equivalence ratios and preheating temperatures, and these were compared to numerical results from Computational Fluid Dynamics (CFD) simulations that used the Reynolds Averaged Navier-Stokes Probability Density Function (RANS-PDF) approach coupled with detailed chemical mechanisms. The Leeds 1.5, GRI 3.0 and San Diego mechanisms were used to investigate the effect of the detailed chemical mechanisms. The effects of equivalence ratio and preheating temperature on acetylene production were experimentally and numerically studied. The experimental validations indicated that the present numerical simulation provided reliable prediction on the partial oxidation of methane. Using this simulation method the optimal equivalence ratio for acetylene production was determined to be 3.6. Increasing preheating temperature improved acetylene production and shortened greatly the ignition delay time. So the increase of preheating temperature had to be limited to avoid uncontrolled ignition in the mixing chamber and the pyrolysis of methane in the preheater.

  7. Effects of Interlayer Distance and van der Waals Energy on Electrochemical Activation of Partially Reduced Graphite Oxide

    International Nuclear Information System (INIS)

    Partially reduced graphite oxide (GOpr) inherits expanded interlayer distance from the parent, graphite oxide (GO), and electronic conductivity from the grandparent, graphite. Indebted to the dual properties, GOpr shows unique behavior so-called electrochemical activation in organic electrolytes; when GOpr is polarized over a certain electrode potential, graphitic layers in GOpr are injected by solvated ions and become ion adsorbing sites permanently. Resultant gravimetric or volumetric capacitance (up to 200 F g−1 or 150 F ml−1) exceeds that of commercially available activated carbon electrodes for electric double-layer capacitor (EDLC). Previous literatures have reported that larger interlayer distance (d) lowers the on-set potential of electrochemical activation of graphitic carbons. However, the reason of this phenomenon has not yet been studied. In this paper, we combined experimental and theoretical approaches to reveal the effect of interlayer distance and van der Waals energy (UvdW) on the electrochemical activation of graphitic carbon. More specifically, we compared the energy for the electrochemical activation (UEA) and the van der Waals energy with respect to the interlayer distance. For this purpose, we devised an experimental method to measure UEA from cyclic voltammogram, and this method was verified by in-situ electrochemical dilatometry. The theoretical value of UvdW was calculated by semi-empirical density functional theory (DFT) and those experimental and theoretical values were linearly in accordance with each other. This finding signifies that (1) the electrochemical activation of graphitic carbon occurs by overcoming van der Waals energy to expand the interlayer distance, (2) and the on-set potential for electrochemical activation is varied by the interlayer distance because of the different van der Waals energy

  8. Copper catalysed synthesis of indolylquinazolinone alkaloid bouchardatine

    Indian Academy of Sciences (India)

    Mayavan Viji; Rajagopal Nagarajan

    2014-07-01

    We describe the total synthesis of indolylquinazolinone alkaloid bouchardatine and some of the quinazolinone derivatives. The aerobic oxidation induced by copper(I) bromide, followed by Vilsmeier-Haack formylation gives the natural product bouchardatine alkaloid in good yield.

  9. Key processes in ruthenium-catalysed olefin metathesis.

    Science.gov (United States)

    Nelson, David J; Manzini, Simone; Urbina-Blanco, César A; Nolan, Steven P

    2014-09-18

    While the fundamental series of [2+2]cycloadditions and retro[2+2]cycloadditions that make up the pathways of ruthenium-catalysed metathesis reactions is well-established, the exploration of mechanistic aspects of alkene metathesis continues. In this Feature Article, modern mechanistic studies of the alkene metathesis reaction, catalysed by well-defined ruthenium complexes, are discussed. Broadly, these concern the processes of pre-catalyst initiation, propagation and decomposition, which all have a considerable impact on the overall efficiency of metathesis reactions.

  10. Key processes in ruthenium-catalysed olefin metathesis.

    Science.gov (United States)

    Nelson, David J; Manzini, Simone; Urbina-Blanco, César A; Nolan, Steven P

    2014-09-18

    While the fundamental series of [2+2]cycloadditions and retro[2+2]cycloadditions that make up the pathways of ruthenium-catalysed metathesis reactions is well-established, the exploration of mechanistic aspects of alkene metathesis continues. In this Feature Article, modern mechanistic studies of the alkene metathesis reaction, catalysed by well-defined ruthenium complexes, are discussed. Broadly, these concern the processes of pre-catalyst initiation, propagation and decomposition, which all have a considerable impact on the overall efficiency of metathesis reactions. PMID:24931143

  11. Catalytic Partial Oxidation of Methane with Air to Syngas in a Pilot-Plant-Scale Spouted Bed Reactor

    Institute of Scientific and Technical Information of China (English)

    魏伟胜; 徐建; 方大伟; 鲍晓军

    2003-01-01

    On the basis of hydrodynamic and scaling-up studies, a pilot-plant-scale thermal spouted bed reactor (50 mm in ID and 1500 mm in height) was designed and fabricated by scaling-down cold simulators. It was tested for making syngas via catalytic partial oxidation (CPO) of methane by air. The effects of various operating conditions such as operating pressure and temperature, feed composition, and gas flowrate etc. on the CPO process were investigated. CH4 conversion of 92.20% and selectivity of 92.3% and 83.30/0 to CO and H2, respectively, were achieved at the pressure of 2.1 MPa. It was found that when the spouted bed reactor was operated within the stable spouting flow regime, the temperature profiles along the bed axis were much more uniform than those operated within the fixed-bed regime. The CH4 conversion and syngas selectivity were found to be close to thermodynamic equilibrium limits. The results of the present investigation showed that spouted bed could be considered as a potential type of chemical reactor for the CPO process of methane.

  12. Molybdenum carbide supported nickel-molybdenum alloys for synthesis gas production via partial oxidation of surrogate biodiesel

    Science.gov (United States)

    Shah, Shreya; Marin-Flores, Oscar G.; Norton, M. Grant; Ha, Su

    2015-10-01

    In this study, NiMo alloys supported on Mo2C are synthesized by wet impregnation for partial oxidation of methyl oleate, a surrogate biodiesel, to produce syngas. When compared to single phase Mo2C, the H2 yield increases from 70% up to >95% at the carbon conversion of ∼100% for NiMo alloy nanoparticles that are dispersed over the Mo2C surface. Supported NiMo alloy samples are prepared at two different calcination temperatures in order to determine its effect on particle dispersion, crystalline phase and catalytic properties. The reforming test data indicate that catalyst prepared at lower calcination temperature shows better nanoparticle dispersion over the Mo2C surface, which leads to higher initial performance when compared to catalysts synthesized at higher calcination temperature. Activity tests using the supported NiMo alloy on Mo2C that are calcined at the lower temperature of 400 °C shows 100% carbon conversion with 90% H2 yield without deactivation due to coking over 24 h time-on-stream.

  13. Formation of polymerization compounds during thermal oxidation of cottonseed oil, partially hydrogenated cottonseed oil and their blends

    Directory of Open Access Journals (Sweden)

    Barrera-Arellano, D. Laboratório de Óleos e Gorduras, Departa

    2006-09-01

    Full Text Available Samples of cottonseed oil, partially hydrogenated cottonseed oil and their blends, with iodine values between 60 and 110, tocopherol-stripped or not by aluminium oxide treatment, were submitted to thermal oxidation, at 180 °C, for 10 hours. Samples were collected at 0, 2, 5, 8 and 10 hours, for the determination of dimers and polymers (degradation compounds and of tocopherols. The influence of the degree of hydrogenation on the formation of dimers and polymers and the role of originally present tocopherols in the protection of fats and oils against thermal degradation was verified. The degradation curves for tocopherols showed a fast destruction rate for the tocopherols present in cottonseed fats and oil (α and γ-tocopherols, with residual levels close to zero after 10 hours under thermal oxidation conditions. Nevertheless, samples with their natural tocopherols presented a slower rate of thermal degradation. The unsaturation degree was apparently more important in the protection against thermal degradation than the content of tocopherolsMuestras de aceite de algodón, aceite de algodón parcialmente hidrogenado y sus mezclas, con índices de yodo de 60 a 110, tratadas o no con óxido de aluminio, fueron sometidas a termoxidación, a 180 °C, durante 10 horas. Se retiraron muestras en los tiempos 0, 2, 5, 8 y 10 horas, para determinación de dímeros y polímeros (compuestos de degradación y de tocoferoles. Se verificó la influencia del grado de hidrogenación sobre la formación de dímeros y polímeros, y también el papel de los tocoferoles originalmente presentes en el aceite y en las grasas, en la protección contra la degradación térmica. Las curvas de degradación de los tocoferoles mostraron una destrucción bastante rápida de los tocoferoles presentes en el aceite y en las grasas de algodón (α y γ-tocoferoles, con niveles residuales próximos a cero después de 10 horas de termoxidación. Aún así, muestras con sus

  14. Acetic acid assisted cobalt methanesulfonate catalysed chemoselective diacetylation of aldehydes

    Institute of Scientific and Technical Information of China (English)

    Min Wang; Zhi Guo Song; Hong Gong; Heng Jiang

    2008-01-01

    Cobalt methanesulfonate in combination with acetic acid catalysed the chemoselective diacetylation of aldehyde with acetic anhydride at room temperature under solvent free conditions. After reaction, cobalt methanesulfonate can be easily recovered and mused many times. The reaction was mild and efficient with good to high yields.

  15. Chiral amides via copper-catalysed enantioselective conjugate addition

    NARCIS (Netherlands)

    Schoonen, Anne K.; Fernández-Ibáñez, M. Ángeles; Fañanás-Mastral, Martín; Teichert, Johannes F.; Feringa, Bernard

    2014-01-01

    A highly enantioselective one pot procedure for the synthesis of β-substituted amides was developed starting from the corresponding α,β-unsaturated esters. This new methodology is based on the copper-catalysed enantioselective conjugate addition of Grignard reagents to α,β-unsaturated esters and sub

  16. CeO2 as the Oxygen Carrier for Partial Oxidation of Methane to Synthesis Gas in Molten Salts: Thermodynamic Analysis and Experimental Investigation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A new technique - the direct partial oxidation of methane to synthesis gas using lattice oxygen in molten salts medium has been introduced. Using CeO2 as the oxygen carrier, thermodynamic data were calculated in the reaction process, and the results indicated that direct partial oxidation of methane to synthesis gas using lattice oxygen of cerium oxide is feasible in theory. In a stainless steel reactor, the effects of temperature and varying amounts of γ-Al2O3 supported CeO2 on CH4 conversion,H2 and CO selectivity, were investigated, respectively. The results show that 10% CeO2/γ-Al2O3 has the maximal reaction activity at a temperature of 865 ℃ and above, the H2/CO ratio in the gas that has been produced reaches 2 and the CH4 conversion, H2 and CO selectivity reached the following percentages: i.e.61%, 89%, and 91% at 870 ℃, respectively. In addition, increase of reaction temperature is favorable for the partial oxidation of methane.

  17. Bias-induced migration of ionized donors in amorphous oxide semiconductor thin-film transistors with full bottom-gate and partial top-gate structures

    Directory of Open Access Journals (Sweden)

    Mallory Mativenga

    2012-09-01

    Full Text Available Bias-induced charge migration in amorphous oxide semiconductor thin-film transistors (TFTs confirmed by overshoots of mobility after bias stressing dual gated TFTs is presented. The overshoots in mobility are reversible and only occur in TFTs with a full bottom-gate (covers the whole channel and partial top-gate (covers only a portion of the channel, indicating a bias-induced uneven distribution of ionized donors: Ionized donors migrate towards the region of the channel that is located underneath the partial top-gate and the decrease in the density of ionized donors in the uncovered portion results in the reversible increase in mobility.

  18. Partial conductivities in perovskites CaZr1- x Sc x O3-α ( x = 0.03-0.20) in an oxidation atmosphere

    Science.gov (United States)

    Gorelov, V. P.; Balakireva, V. B.; Kuz'min, A. V.

    2016-01-01

    Partial (ionic, proton, and hole) conductivities of oxides CaZr1- x Sc x O3-α( x = 0.03-0.20) with the perovskite structure in air atmosphere have been studied as functions of temperature in the range of 600-900°C and partial water-vapor pressure in the range of {P_{{H_2}O}}= 40-2500 Pa. The influence of the humidity of the atmosphere on the relative change in the concentration of oxygen vacancies as a function of temperature has been estimated.

  19. Partial Oxidation Gas Turbine for Power and Hydrogen Co-Production from Coal-Derived Fuel in Industrial Applications

    Energy Technology Data Exchange (ETDEWEB)

    Joseph Rabovitser

    2009-06-30

    The report presents a feasibility study of a new type of gas turbine. A partial oxidation gas turbine (POGT) shows potential for really high efficiency power generation and ultra low emissions. There are two main features that distinguish a POGT from a conventional gas turbine. These are associated with the design arrangement and the thermodynamic processes used in operation. A primary design difference of the POGT is utilization of a non?catalytic partial oxidation reactor (POR) in place of a conventional combustor. Another important distinction is that a much smaller compressor is required, one that typically supplies less than half of the air flow required in a conventional gas turbine. From an operational and thermodynamic point of view a key distinguishing feature is that the working fluid, fuel gas provided by the OR, has a much higher specific heat than lean combustion products and more energy per unit mass of fluid can be extracted by the POGT expander than in the conventional systems. The POGT exhaust stream contains unreacted fuel that can be combusted in different bottoming ycle or used as syngas for hydrogen or other chemicals production. POGT studies include feasibility design for conversion a conventional turbine to POGT duty, and system analyses of POGT based units for production of power solely, and combined production of power and yngas/hydrogen for different applications. Retrofit design study was completed for three engines, SGT 800, SGT 400, and SGT 100, and includes: replacing the combustor with the POR, compressor downsizing for about 50% design flow rate, generator replacement with 60 90% ower output increase, and overall unit integration, and extensive testing. POGT performances for four turbines with power output up to 350 MW in POGT mode were calculated. With a POGT as the topping cycle for power generation systems, the power output from the POGT ould be increased up to 90% compared to conventional engine keeping hot section temperatures

  20. An Overview of Recent Advances of the Catalytic Selective Oxidation of Ethane to Oxygenates

    Directory of Open Access Journals (Sweden)

    Robert D. Armstrong

    2016-05-01

    Full Text Available The selective partial oxidation of short chain alkanes is a key challenge within catalysis research. Direct ethane oxidation to oxygenates is a difficult aim, but potentially rewarding, and it could lead to a paradigm shift in the supply chain of several bulk chemicals. Unfortunately, low C–H bond reactivity and kinetically labile products are just some reasons affecting the development and commercialisation of such processes. Research into direct ethane oxidation is therefore disparate, with approaches ranging from oxidation in the gas phase at high temperatures to enzyme catalysed hydroxylation under ambient conditions. Furthermore, in overcoming the barrier posed by the chemically inert C–H bond a range of oxidants have been utilised. Despite years of research, this remains an intriguing topic from both academic and commercial perspectives. Herein we describe some recent developments within the field of catalytic ethane oxidation focusing on the formation of oxygenated products, whilst addressing the key challenges which are still to be overcome.

  1. Oxidative stability and antioxidant enzyme activities of dry-cured bacons as affected by the partial substitution of NaCl with KCl.

    Science.gov (United States)

    Wu, Haizhou; Yan, Wenjing; Zhuang, Hong; Huang, Mingming; Zhao, Jianying; Zhang, Jianhao

    2016-06-15

    This study investigated the influence of partial substitution of NaCl with KCl on protein and lipid oxidation as well as antioxidant enzyme activities in dry-cured bacons during processing. The partial substitution was 0% KCl (I), 40% KCl (II), and 70% KCl (III). Compared with 0% KCl (I), the substitution of 40% NaCl with KCl did not significantly influence the protein and lipid oxidation and antioxidant enzyme activities. The bacons that were treated with 70% KCl treatment (III) showed increased lipid oxidation and antioxidant enzyme GSH-Px activity, whereas samples treated with formulas I and II showed higher protein oxidation and antioxidant enzyme catalase activity. These results demonstrate that the substitution of NaCl with KCl by more than 40% may significantly affect protein and lipid oxidation and that for the substitution of NaCl in further processed meat products with other chloride salts, salt content is very important for control of protein and lipid biochemical changes in finished products. PMID:26868571

  2. Hydrogen production by partial oxidation of ethanol at supported Ni and Co catalysts; Wasserstofferzeugung durch Partialoxidation von Ethanol an getraegerten Ni und Co Katalysatoren

    Energy Technology Data Exchange (ETDEWEB)

    Kraleva, E.; Ehrich, H. [Rostock Univ. (Germany). Leibniz-Institut fuer Katalyse e.V.

    2011-07-01

    Hydrogen for SOFC fuel cells is produced by catalytic partial oxidation of ethanol in an internal reformer of the fuel cell system. Experiments with low-cost metals like nickel and cobalt on different supports showed great promise for ethanol conversion. The catalysts have been prepared by a new sol-gel method using citric acid as a chelating agent. This efficient low-cost method for the synthesis of mixed metal oxides resulted in catalysts with higher surface areas than impregnated catalysts. (orig.)

  3. Nitrous oxide production pathways in a partial nitritation-anammox reactor: Isotopic evidence for nitrous oxide production associated anaerobic ammonium oxidation?

    Science.gov (United States)

    Wunderlin, P.; Harris, E. J.; Joss, A.; Emmenegger, L.; Kipf, M.; Mohn, J.; Siegrist, H.

    2014-12-01

    Nitrous oxide (N2O) is a strong greenhouse gas and a major sink for stratospheric ozone. In biological wastewater treatment N2O can be produced via several pathways. This study investigates the dynamics of N2O emissions from a nitritation-anammox reactor, and links its interpretation to the nitrogen and oxygen isotopic signature of the emitted N2O. A 400-litre single-stage nitritation-anammox reactor was operated and continuously fed with digester liquid. The isotopic composition of N2O emissions was monitored online with quantum cascade laser absorption spectroscopy (QCLAS; Aerodyne Research, Inc.; Waechter et al., 2008). Dissolved ammonium and nitrate were monitored online (ISEmax, Endress + Hauser), while nitrite was measured with test strips (Nitrite-test 0-24mgN/l, Merck). Table 1. Summary of experiments conducted to understand N2O emissions Experimental conditions O2[mgO2/L] NO2-[mgN/L] NH4+[mgN/L] N2O/NH4+[%] Normal operation reactor. Our data reveal that N2O emissions increased when reactor operation was not ideal, for example when dissolved oxygen was too high (Table 1). SP measurements confirmed that these N2O peaks were due to enhanced nitrifier denitrification, generally related to nitrite build-up in the reactor (Figure 1; Table 1). Overall, process control via online N2O monitoring was confirmed to be an ideal method to detect imbalances in reactor operation and regulate aeration, to ensure optimal reactor conditions and minimise N2O emissions. ReferencesWaechter H. et al. (2008) Optics Express, 16: 9239-9244. Wunderlin, P et al. (2013) Environmental Science & Technology 47: 1339-1348.

  4. Enhanced oxidative stress and platelet activation combined with reduced antioxidant capacity in obese prepubertal and adolescent girls with full or partial metabolic syndrome.

    Science.gov (United States)

    Karamouzis, I; Pervanidou, P; Berardelli, R; Iliadis, S; Papassotiriou, I; Karamouzis, M; Chrousos, G P; Kanaka-Gantenbein, C

    2011-08-01

    In adults, obesity is a main factor implicated in increased oxidative stress (OS), platelet activation (PA) and impaired antioxidant status (AS), all predisposing factors for cardiovascular disease leading to increased morbidity and mortality. Furthermore, the metabolic syndrome (MetS) is an important cardiovascular risk factor, which progressively develops and may already be present during late childhood or adolescence. However, scarce data exist on oxidative-antioxidant balance and PA in childhood and adolescence in the presence of partial (PMetS) or full MetS. The aim of the study was to evaluate OS, PA, and AS in prepubertal and adolescent obese girls with partial or full MetS. 96 girls with a clinical and metabolic evaluation for obesity and 44 healthy normal-weight sex- and age-matched girls were studied. IDF-adopted criteria were used to define full and partial MetS and the patient population was divided into 4 groups: the first comprised 31 pre-pubertal girls with PMetS (PR-PMetS), the second 37 adolescents with PMetS (AD-PMetS), the third 10 prepubertal girls with full MetS (PR-MetS), and the fourth 18 adolescents with full MetS (AD-MetS). The OS was evaluated by measuring plasma 15-F(2t)-Isoprostane levels (15-F(2t)-IsoP) and protein carbonyls, PA by thromboxane B(2) levels (TXB(2)), and AS by serum vitamin E and plasma total antioxidant capacity (TAC) levels. 15-F(2t)-IsoP, protein carbonyls, and TXB(2) levels were significantly gradually amplified, and vitamin E and TAC reduced, and significantly correlated with obesity from childhood to adolescence and from partial to full MetS. This study demonstrates the loss of the normal homeostatic balance between oxidant-antioxidant state in obese children and adolescents with manifestations of partial and full MetS. PMID:21823055

  5. Combined effect of low-dose nitric oxide gas inhalation with partial liquid ventilation on hemodynamics, pulmonary function, and gas exchange in acute lung injury of newborn piglets.

    OpenAIRE

    Choi, Chang Won; Hwang, Jong Hee; Chang, Yun Sil; Park, Won Soon

    2003-01-01

    We conducted a randomized animal study to determine whether there is a cumulative effect on hemodynamics, pulmonary function, and gas exchange when low-dose nitric oxide (NO) is added to partial liquid ventilation (PLV) in acute lung injury. Eighteen newborn piglets were saline-lavaged repeatedly, and randomly divided into two groups: PLV with perfluorocarbon group (n=8) and lavage only (control) group (n=10). Perfluorodecalin (30 mL/kg) was instilled into the endotracheal tube for 30 min, fo...

  6. Uptake of deuterium in partially D-depleted residual codeposits left on DIII-D tiles after laboratory thermo-oxidation experiments

    Science.gov (United States)

    Fitzpatrick, B. W. N.; Davis, J. W.; Haasz, A. A.

    2012-01-01

    Recent evidence has shown that tokamak carbon-based codeposits may become partially or fully depleted of hydrogen through thermo-oxidation, as the hydrogen content of the codeposits is removed more rapidly than the carbon content. In this study we examine the ability of such partially-depleted residual DIII-D divertor codeposits to uptake deuterium upon subsequent exposure to deuterium gas or deuterium plasmas. The partially D-depleted specimens used here were obtained from a previous study where DIII-D codeposits were oxidized for 2 h at 623 K (350 °C) and 267 Pa (2 Torr) O 2 [J.W. Davis et al., Thermo-oxidation of DIII-D codeposits on open surfaces and in simulated tile gaps, J. Nucl. Mater. 415 (2011) S789-S792]. In the present study some of these specimens, having undergone prior oxidation, were exposed to D 2 glow discharge plasmas or D 2 gas at 20 kPa (150 Torr) at 300 or 523 K. In the case of plasma exposure, no uptake of D was observed, while an increase in D content was seen following D 2 gas exposures. When the gas exposure took place at 300 K, heating the specimens in vacuum to 623 K for 15 min led to the release of all of the increased D content. For the gas exposure at 523 K, the increase in D content was found to require longer (8 h) vacuum baking to remove. However, in a reference codeposit specimen (from a closeby location on the tile), which had not been previously oxidized, there was a similar increase in D content following D 2 exposure at 523 K, but it could not be released even following 8 h vacuum baking at 623 K.

  7. Uptake of deuterium in partially D-depleted residual codeposits left on DIII-D tiles after laboratory thermo-oxidation experiments

    International Nuclear Information System (INIS)

    Recent evidence has shown that tokamak carbon-based codeposits may become partially or fully depleted of hydrogen through thermo-oxidation, as the hydrogen content of the codeposits is removed more rapidly than the carbon content. In this study we examine the ability of such partially-depleted residual DIII-D divertor codeposits to uptake deuterium upon subsequent exposure to deuterium gas or deuterium plasmas. The partially D-depleted specimens used here were obtained from a previous study where DIII-D codeposits were oxidized for 2 h at 623 K (350 °C) and 267 Pa (2 Torr) O2 [J.W. Davis et al., Thermo-oxidation of DIII-D codeposits on open surfaces and in simulated tile gaps, J. Nucl. Mater. 415 (2011) S789–S792]. In the present study some of these specimens, having undergone prior oxidation, were exposed to D2 glow discharge plasmas or D2 gas at 20 kPa (150 Torr) at 300 or 523 K. In the case of plasma exposure, no uptake of D was observed, while an increase in D content was seen following D2 gas exposures. When the gas exposure took place at 300 K, heating the specimens in vacuum to 623 K for 15 min led to the release of all of the increased D content. For the gas exposure at 523 K, the increase in D content was found to require longer (8 h) vacuum baking to remove. However, in a reference codeposit specimen (from a closeby location on the tile), which had not been previously oxidized, there was a similar increase in D content following D2 exposure at 523 K, but it could not be released even following 8 h vacuum baking at 623 K.

  8. Temporal resilience and dynamics of anaerobic methane-oxidizing microbial communities to short-term changes in methane partial pressures

    Science.gov (United States)

    Klasek, S.; Tiantian, Y.; Torres, M. E.; Colwell, F. S.; Wang, F.; Liang, L.

    2015-12-01

    Marine sediments produce tens to hundreds of teragrams of methane annually, which is released from the seabed at thousands of cold seeps distributed globally along continental margins. Around 80-90% of this methane is consumed in shallower sediment layers before reaching the hydrosphere, in a microbially-mediated process known as anaerobic oxidation of methane (AOM) However, cold seeps appear to exhibit temporal variation in gas flux intensity, and AOM filter efficiency at cold seeps generally decreases with fluid flow rate. To our knowledge, the degree to which temporal heterogeneity in subsurface methane flux stimulates AOM community growth and adaptation to increased methane concentrations has not been investigated. Static high-pressure bioreactors were used to incubate sulfate-methane transition zone (SMTZ) and methanogenic zone sediments underlying a Mediterranean mud volcano gas flare under in situ temperature and pressure at 8 MPa methane. Sulfide production rates of 0.4 μmol/cm3/day in both sediment regimes after 4 months of incubation suggested the resilience of the marine subsurface methane filter may extend well below the SMTZ (40 cm). Similar incubations of SMTZ samples from below a gas flare off Svalbard at saturating (3.8 MPa) and 0.2 MPa methane are being sampled after 1 week, 4 weeks, and 4 months; sulfide production rates of 8-18 nmol/cm3/day were first observed after 4 weeks of incubation. Sediment samples at all specified time points for both sets of incubations were collected for nucleic acid extraction and cell fixation. Anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB) are expected dominant taxa in enriched and non-enriched communities. 16S rDNA community analysis is expected to reveal additional microbial players involved in the short-term adaptation to higher methane partial pressures in the marine subsurface. Increased AOM community activity (RNA/DNA ratio) and copy numbers of methane cycling transcripts (mcr

  9. Nickel-catalysed Suzuki-Miyaura coupling of amides

    Science.gov (United States)

    Weires, Nicholas A.; Baker, Emma L.; Garg, Neil K.

    2016-01-01

    The Suzuki-Miyaura coupling has become one of the most important and prevalent methods for the construction of C-C bonds. Although palladium catalysis has historically dominated the field, the use of nickel catalysis has become increasingly widespread because of its unique ability to cleave carbon-heteroatom bonds that are unreactive towards other transition metals. We report the first nickel-catalysed Suzuki-Miyaura coupling of amides, which proceeds by an uncommon cleavage of the amide C-N bond after N-tert-butoxycarbonyl activation. The methodology is mild, functional-group tolerant and can be strategically employed in sequential transition-metal-catalysed cross-coupling sequences to unite heterocyclic fragments. These studies demonstrate that amides, despite classically considered inert substrates, can be harnessed as synthons for use in reactions that form C-C bonds through cleavage of the C-N bond using non-precious metal catalysis.

  10. Carbon–heteroatom bond formation catalysed by organometallic complexes

    OpenAIRE

    Hartwig, John F.

    2008-01-01

    At one time the synthetic chemist’s last resort, reactions catalysed by transition metals are now the preferred method for synthesizing many types of organic molecule. A recent success in this type of catalysis is the discovery of reactions that form bonds between carbon and heteroatoms (such as nitrogen, oxygen, sulphur, silicon and boron) via complexes of transition metals with amides, alkoxides, thiolates, silyl groups or boryl groups. The development of these catalytic processes has been ...

  11. A New Class of Highly Dispersed VOx Catalysts on Mesoporous Silica: Synthesis, Characterization, and Catalytic Activity in the Partial Oxidation of Ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Ja Hun; Herrera, Jose E.; Hu, Jian Zhi; Wang, Yong; Peden, Charles HF

    2006-01-26

    The morphology of vanadium oxide supported on a titania-modified mesoporous silica (MCM-41), obtained by means of a careful grafting process through atomic layer deposition, was studied using a variety of characterization techniques. The XRD together with TEM, 51V-NMR, Raman, FTIR and DRS-UV-Vis results showed that the vanadia species are extremely well dispersed onto the surface of the mesoporous support; the dispersion being stable upon thermal treatments up to 400 °C. Studies of the catalytic activity of these materials were performed using the partial oxidation of ethanol as a probe reaction. The results indicate an intrinsic relationship between dispersion, the presence of a TiO2-VOx phase, and catalytic activity for oxidation and dehydration.

  12. Effect of partial pressure of reactive gas on chromium nitride and chromium oxide deposited by arc ion plating

    Institute of Scientific and Technical Information of China (English)

    LI Ming-sheng; FENG Chang-jie; WANG Fu-hui

    2006-01-01

    The effects of reactive gas partial pressure on droplet formation,deposition rate and change of preferred orientation of CrN and Cr2O3 coatings were studied. For CrN coatings,as nitrogen partial pressure increases,the number and size of droplets increases,the deposition rate initially increases obviously and then slowly,and the preferred orientation of CrN changes from high-index plane to low-index one. For Cr2O3 coatings,with the increase of oxygen partial pressure,the number and size of droplets decreases,the deposition rate decreases and the (300) becomes the preferred orientation. These differences are ascribed to the formation of CrN (with a lower melting point) and Cr2O3 (with a higher melting point) on the surface of Cr target during the deposition of CrN and Cr2O3. Complete coatings CrN or Cr2O3 film can be formed when reactive gas partial pressure gets up to 0.1 Pa. The optimized N2 partial pressure for CrN deposition is about 0.1-0.2 Pa in order to suppress the formation of droplets and the suitable O2 partial pressure for Cr2O3 deposition is approximately 0.1 Pa for the attempt to prevent the peel of the coating.

  13. Effect of partial oxygen pressure on physicochemical properties of Kh18N10T steel at isothermal oxidation

    International Nuclear Information System (INIS)

    Auger-electron spectroscopy, photoelectric polarization, conductometry methods have been used to analyze chemical and defect composition of surface oxide layers, formed on stainless steel Kh18N10T in vacuum (10-9 - 10-2 torr) and at temperatures 593-673 K. The boundary conditions of manifestation of extermal behaviour of the dependence of the surface oxide growth rate at isothermal oxidation of this steel are determined. The relation between passivation properties of the surface oxide and the magnitude of the edge angle of the surface wetting with molten tin is revealed

  14. Laccase catalysed grafting of phenolic onto xylan to improve its applicability in films

    Science.gov (United States)

    Pei, Jicheng; Wang, Bing; Zhang, Fangdong; Li, Zhongyang; Yin, Yunbei; Zhang, Dongxu

    2015-07-01

    Xylan can be tailored for various value-added applications. However, its use in aqueous systems is hampered by its complex structure, and small molecular weight. This research aimed at improving the xylan molecular weight and changing its structure. Laccase-catalysed oxidation of 4-coumaric acid (PCA), ferulic acid (FA), syringaldehyde (SD), and vanillin (VA) onto xylan was grafted to study the changes in its structure, tensile properties, and antibacterial activities. A Fourier transform infrared (FTIR) spectrum analyser was used to observe the changes in functional groups of xylan. The results showed a band at 1635 cm-1 corresponding to the stretching vibration of conjugated carbonyl carboxy hemoglobin and a benzene ring structure were strengthened; the appearance of a new band between 1200 cm-1 and 1270 cm-1 corresponding to alkyl ethers on the aryl C-O stretching vibration was due to the fact that during the grafting process, the number of benzene ring structures increased and covalent connections occurred between phenols and xylan. The reaction mechanism for the laccase-catalysed oxidation of phenol compounds onto xylan was preliminary explored by 13C-NMR. The results showed that PCA-xylan, FA-xylan graft poly onto xylan by Cγ ester bond, SD-xylan graft poly onto xylan by ether bond and an ester bond, and VD-xylan graft poly onto xylan by ether bond. The film strength of xylan derivatives has been significantly increased, especially for the PCA-xylan derivative. The increases in tensile stress at break, tensile strength, tensile yield stress, and Young's modulus were: 24.04%, 31.30%, 55.56%, and 28.21%, respectively. After laccase/phenolics were modified, xylan had a good antibacterial effect to E. coli, Corynebacterium glutamicum, and Bacillus subtilis. The SD-xylan, FA-xylan, and PCA-xylan showed a greater efficacy against E. coli, Corynebacterium glutamicum, and Bacillus subtilis, respectively.

  15. Research Progress on Preparation of Synthetic Gas by Partial Oxidation of Natural Gas%天然气部分氧化制合成气的研究进展

    Institute of Scientific and Technical Information of China (English)

    向文军; 王佩怡

    2012-01-01

    To summary the research progress on preparation of synthetic gas by partial oxidation of natural gas,including non-catalytic partial oxidation of natural gas, fixed bed catalytic partial oxidation, two-stage reforming method, membrane reactor,fluidization bed process,oxidant study, partial oxidation by microwave radiation heating, mechanism of partial oxidation and study of catalysts for partial oxidation process.%综述了天然气部分氧化制合成气的研究进展,包括天然气无催化部分氧化、固定床催化部分氧化、两段转化法、膜反应器新工艺、流化床反应工艺、氧化剂研究、微波辐射加热部分氧化、部分氧化的机理,以及部分氧化工艺的催化剂研究。

  16. Experimental kinetic study of oxidation of uranium monocarbide powders under controlled oxygen partial pressures below 230 °C

    International Nuclear Information System (INIS)

    Uranium monocarbide (UC) powders are known to be easily oxidised by gas mixtures containing oxygen. In this study, the oxidation of UC micron powders was followed by isothermal thermogravimetry at temperatures ranging from 100 °C to 230 °C in two different gas mixtures: synthetic air and 97%N2 + 3%O2. X-ray diffraction tests conducted on powders after their oxidation showed that small crystallites of UO2 oxide are formed. Furthermore, an analysis of mass gain showed that the carbon initially linked with the uranium is not oxidised but retained in oxide layers. Additionally, this kinetic study revealed that the rate-limiting step mechanism governing the oxidation of UC powders is a diffusive process that follows the Arrhenius law regarding temperature. Finally, it was discovered that cracks occur in grains once a given fractional conversion has been reached, inducing a major increase in the volume of grains.

  17. Methane partial oxidation using Ni/Ce{sub 0.9}Zr{sub 0.1}O{sub 2} catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Larrondo, S.A.; Kodjaian, A.; Amadeo, N.E. [Laboratorio de Procesos Cataliticos, Departamento de Ingenieria Quimica, Facultad de Ingenieria, Universidad de Buenos Aires, Pabellon de Industrias, Ciudad Universitaria, 1428, Buenos Aires (Argentina); Fabregas, I.; Zimicz, M.G.; Lamas, D.G.; Walsoee de Reca, B.E. [CINSO (Centro de Investigaciones en Solidos), CONICET-CITEFA, J.B. de La Salle 4397 (1603) Villa Martelli, Pcia. de Buenos Aires (Argentina)

    2008-07-15

    The development of active and selective catalysts for methane partial oxidation is one of today's challenges, because these catalysts could be used either for hydrogen production purposes or as anode materials in single-chamber solid oxide fuel cells (SOFCs). In this work, the synthesis of ceria-zirconia solid solutions of nominal composition Ce{sub 0.9}Zr{sub 0.1}O{sub 2} through the gel-combustion route is presented. The solids obtained were impregnated with nickel solutions to achieve contents of 9% and 50% (m/m), characterized texturally and structurally, and their catalytic behavior in the methane partial oxidation reaction was assessed. The synthesis method was effective, leading to solids with good morphological properties. Likewise, the Ni/Ce{sub 0.9}Zr{sub 0.1}O{sub 2} catalysts proved to be active and showed a stable behavior during the working period, with methane conversion levels of 90% at temperatures above 550 C, being hydrogen and carbon monoxide the main products. (author)

  18. Catalytic partial oxidation of coke oven gas to syngas in an oxygen permeation membrane reactor combined with NiO/MgO catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhibin; Ding, Weizhong; Zhang, Yunyan; Lu, Xionggang; Zhang, Yuwen; Shen, Peijun [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, No. 275 Mail box, 149 Yanchang Road, Shanghai 200072 (China)

    2010-06-15

    A high oxygen permeability and sufficient chemical and mechanical stability mixed ion and electron conductivity membrane to withstand the hash strong oxidation and reduction working conditions is significant for the membrane reactor to commercial-scale plant. In this paper, a disk-shaped Ba{sub 1.0}Co{sub 0.7}Fe{sub 0.2}Nb{sub 0.1}O{sub 3-{delta}} membrane was applied to a membrane reactor for the partial oxidation of methane in coke oven gas (COG) to syngas. The reaction was carried out using NiO/MgO solid solution catalyst by feeding COG. The reforming process was performed successfully; 95% CH{sub 4} conversion, 80% H{sub 2} selectivity, 106% CO selectivity and 16.3 ml cm{sup -2} min{sup -1} oxygen permeation flux were achieved at 1148 K. The reaction has been steadily carried out for more than 100 h. The NiO/MgO catalyst used in the membrane reactor exhibited good catalytic activity and resistance to coking in the COG atmosphere. Characterization of the membrane surface by SEM and XRD after long life test showed that both the surface exposed to the air side and reaction side still preserved the Perovskite structure which is implied that the practical application of this membrane as membrane reactor for partial oxidation of COG is promising. (author)

  19. Accumulation and reactions of H2O2 during the copper ion catalysed autoxidation of cysteine in alkaline medium

    OpenAIRE

    Koningsberger, D.C.; De Zwart, J.; Wolput, J.H.M.C. van; Cammen, J.C.J.M. van der

    1981-01-01

    The stoichiometry of the copper catalysed alkaline autoxidation of cysteine has been investigated. Products of this oxidation reaction are cystine, H{2}O{2} and H{2}O. No oxygen containing sulfur acids are produced as long as cysteine is present in the reaction liquid.The H{2}O{2} generated reacts with cysteine selectively to form cystine and H{2}O with r{H}{2}{O}{2} = k{H}{2}{O}{2} [CyS][H{2}O{2}] (k{H}{2}{O}{2} = 0.17 1 mol}-{}1{ s}-{}1{).The reaction between H{2}O{2} and cysteine is not ca...

  20. Ru-Catalysed C–H Arylation of Indoles and Pyrroles with Boronic Acids: Scope and Mechanistic Studies

    Science.gov (United States)

    Sollert, Carina; Devaraj, Karthik; Orthaber, Andreas; Gates, Paul J; Pilarski, Lukasz T

    2015-01-01

    The Ru-catalysed C2–H arylation of indoles and pyrroles by using boronic acids under oxidative conditions is reported. This reaction can be applied to tryptophan derivatives and tolerates a wide range of functional groups on both coupling partners, including bromides and iodides, which can be further derivatised selectively. New indole-based ruthenacyclic complexes are described and investigated as possible intermediates in the reaction. Mechanistic studies suggest the on-cycle intermediates do not possess a para-cymene ligand and that the on-cycle metalation occurs through an electrophilic attack by the Ru centre. PMID:25689052

  1. Ni/SiO2 Catalyst Prepared with Nickel Nitrate Precursor for Combination of CO2 Reforming and Partial Oxidation of Methane: Characterization and Deactivation Mechanism Investigation

    OpenAIRE

    2015-01-01

    The performance of Ni/SiO2 catalyst in the process of combination of CO2 reforming and partial oxidation of methane to produce syngas was studied. The Ni/SiO2 catalysts were prepared by using incipient wetness impregnation method with nickel nitrate as a precursor and characterized by FT-IR, TG-DTA, UV-Raman, XRD, TEM, and H2-TPR. The metal nickel particles with the average size of 37.5 nm were highly dispersed over the catalyst, while the interaction between nickel particles and SiO2 support...

  2. Partial Oxidation of Methane with Sol-Gel Fe/Hf/YSZ Catalyst in Dielectric Barrier Discharge: Catalyst Activation by Plasma

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A 1% Fe-30% Hf over yttria-stabilized zirconia catalyst in combination with novel plasma-assisted activation techniques for a direct partial oxidation of methane to methanol was tested using dielectric barrier discharge plasma at ambient temperature and atmospheric pressure. However, instead of methanol, the reaction products were dominated by H2,CO, CO2, C2, and H2O. A catalytically activated plasma process increased the production of methanol compared with a noncatalytic plasma process. The maximum selectivity of methanol production was achieved using a catalyst that was treated at higher applied power.

  3. Key processes in ruthenium-catalysed olefin metathesis

    OpenAIRE

    Nelson, David J.; Manzini, Simone; Urbina-Blanco, César A.; Nolan, Steven P.

    2014-01-01

    The authors acknowledge the following sources of funding: the EPSRC, the ERC (via Advanced Investigator Grant ‘FUNCAT’ to SPN), the EC (via FP7 project ‘EUMET’) and Umicore (for gifts of materials). SPN is a Royal Society Wolfson Research Merit Award holder. While the fundamental series of [2+2]cycloadditions and retro[2+2]cycloadditions that make up the pathways of ruthenium-catalysed metathesis reactions is well-established, the exploration of mechanistic aspects of alkene metathesis con...

  4. Synthesis of New dihydropyrimidinones catalysed by dicationic ionic liquid

    Indian Academy of Sciences (India)

    Dhanaji V Jawale; Umesh R Pratap; Aparna A Mulay; Jyotirling R Mali; Ramrao A Mane

    2011-09-01

    A convenient multi step synthetic protocol for new dihydropyrimidinones bearing quinolynyl methoxy phenyl moiety has been developed from 2-chloro-3-formyl quinolines. The last step is one-pot Biginelli reaction of multicomponents, 4-((2-chloroquinolin-3-yl) methoxy) benzaldehydes, ethyl acetoacetate and urea mediated and catalysed by dicationic ionic liquid (3-methyl-1-[3-(methyl-1H-imidazolium-1-yl) propyl]-1H-imidazolium dibromide (C3 [min]2 2 [Br−] )). Simple work-up procedures and moderate to good yields of the pyrimidinones and the intermediates are the merits of the route.

  5. Effects of MgO promoter on properties of Ni/Al2O3 catalysts for partial oxidation of methane to syngas

    Institute of Scientific and Technical Information of China (English)

    QIU Yejun; CHEN Jixiang; ZHANG Jiyan

    2007-01-01

    The effects of MgO promoter on the physicochemical properties and catalytic performance of Ni/Al2O3 catalysts for the partial oxidation of methane to syngas were studied by means of BET,XRD,H2-TPR,TEM and performance evaluation.It was found that the MgO promoter benefited from the uniformity of nickel species in the catalysts,inhibited the formation of NiAl2O4 spinel and improved the interaction between nickel species and support.These results were related to the formation of NiO-MgO solid solution and MgAl2O4 spinel.Moreover,for the catalysts with a proper amount of MgO promoter,the nickel dispersiveness was enhanced,therefore making their catalytic performance in methane partial oxidation improved.However,the excessive MgO promoter exerted a negative effect on the catalytic performance.Meanwhile,the basicity of MgO promoted the reversed water-gas shift reaction,which led to an increase in CO selectivity and a decrease in H2 selectivity.The suitable content of MgO promoter in Ni/Al2O3 catalyst was~7 wt-%.

  6. Curcumin ameliorated diabetic neuropathy partially by inhibition of NADPH oxidase mediating oxidative stress in the spinal cord.

    Science.gov (United States)

    Zhao, Wei-Cheng; Zhang, Bin; Liao, Mei-Juan; Zhang, Wen-Xuan; He, Wan-You; Wang, Han-Bing; Yang, Cheng-Xiang

    2014-02-01

    Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases are the main enzymes that produce oxidative stress, which plays an important role in painful diabetic neuropathy. Curcumin has been reported to exert an antinociceptive effect in a rat model of diabetic neuropathy by suppressing oxidative stress in the spinal cord. However, it remains unknown whether the mechanism by which curcumin ameliorates diabetic neuropathy can be attributed to spinal NADPH oxidases. This study was designed to determine the effect of curcumin on diabetic neuropathy and to investigate its precise mechanism in relation to NADPH oxidase-mediating oxidative stress in the spinal cord. Diabetic neuropathy was induced in Sprague-Dawley rats by intraperitoneal injection with 1% streptozotocin (STZ; 60 mg/kg). After the onset of diabetic neuropathy, a subset of the diabetic rats received daily intragastric administrations of curcumin (200mg/kg) or intraperitoneal injections of apocynin (2.5mg/kg) for 14 consecutive days, whereas other diabetic rats received equivalent volumes of normal saline (NS). STZ resulted in diabetic neuropathy with hyperglycemia and a lower paw withdrawal threshold (PWT), accompanied by elevations in the expression of the NADPH oxidase subunits p47(phox) and gp91(phox) and in the levels of hydrogen peroxide (H2O2) and malondialdehyde (MDA) and a reduction in superoxide dismutase (SOD) activity (Pdiabetic neuropathy. In conclusion, curcumin attenuated neuropathic pain in diabetic rats, at least partly by inhibiting NADPH oxidase-mediating oxidative stress in the spinal cord.

  7. Rf-sputtered vanadium oxide thin films: effect of oxygen partial pressure on structural and electrochemical properties

    International Nuclear Information System (INIS)

    Vanadium oxide thin films with thickness of about 2000 A have been prepared by radio frequency sputter deposition using a V2O5 target in a mixed argon and oxygen atmosphere with different Ar/O2 ratio ranging from 99/1 to 90/10. X-ray diffraction and X-ray absorption near edge structure spectroscopic studies show that the oxygen content higher than 5% crystallizes a stoichiometric VO5 phase, while oxygen deficient phase is formed in the lower oxygen content. The oxygen content in the mixed Ar + O2 has a significant influence on electrochemical lithium insertion/deinsertion property. The discharge-charge capacity of vanadium oxide film increases with increasing the reactive oxygen content. The VO5 film deposited at the Ar/O2 ratio of 90/10 exhibits high discharge capacity of 100 μAh/cm2-μm along with good cycle performance

  8. SNPs in DNA repair or oxidative stress genes and late subcutaneous fibrosis in patients following single shot partial breast irradiation

    OpenAIRE

    Falvo Elisabetta; Strigari Lidia; Citro Gennaro; Giordano Carolina; Boboc Genoveva; Fabretti Fabiana; Bruzzaniti Vicente; Bellesi Luca; Muti Paola; Blandino Giovanni; Pinnarò Paola

    2012-01-01

    Abstract Background The aim of this study was to evaluate the potential association between single nucleotide polymorphisms related response to radiotherapy injury, such as genes related to DNA repair or enzymes involved in anti-oxidative activities. The paper aims to identify marker genes able to predict an increased risk of late toxicity studying our group of patients who underwent a Single Shot 3D-CRT PBI (SSPBI) after BCS (breast conserving surgery). Methods A total of 57 breast cancer pa...

  9. Hepatic ischemia-reperfusion syndrome after partial liver resection (LR): hepatic venous oxygen saturation, enzyme pattern, reduced and oxidized glutathione, procalcitonin and interleukin-6.

    Science.gov (United States)

    Kretzschmar, Michael; Krüger, Antie; Schirrmeister, Wulf

    2003-06-01

    The hepatic ischemia-reperfusion syndrome was investigated in 28 patients undergoing elective partial liver resection with intraoperative occlusion of hepatic inflow (Pringle maneuver) using the technique of liver vein catheterization. Hepatic venous oxygen saturation (ShvO2) was monitored continuously up to 24 hours after surgery. Aspartate aminotransferase, glutamate dehydrogenase, gamma-glutamyl transpeptidase, pseudocholinesterase, alpha-glutathione S-transferase, reduced and oxidized glutathione, procalcitonine, and interleukin-6 were serially measured both before and after Pringle maneuver during the resection and postoperatively in arterial and/or hepatic venous blood. ShvO2 measurement demonstrated that peri- and postoperative management was suitable to maintain an optimal hepatic oxygen supply. As expected, we were able to demonstrate a typical enzyme pattern of postischemic liver injury. There was a distinct decrease of reduced glutathione levels both in arterial and hepatic venous plasma after LR accompanied by a strong increase in oxidized glutathione concentration during the phase of reperfusion. We observed increases in procalcitonin and interleukin-6 levels both in arterial and hepatic venous blood after declamping. Our data support the view that liver resection in man under conditions of inflow occlusion resulted in ischemic lesion of the liver (loss of glutathione synthesizing capacity with disturbance of protection against oxidative stress) and an additional impairment during reperfusion (liberation of reactive oxygen species, local and systemic inflammation reaction with cytokine production). Additionally, we found some evidence for the assumption that the liver has an export function for reduced glutathione into plasma in man. PMID:12877355

  10. Ni/SiO2 Catalyst Prepared with Nickel Nitrate Precursor for Combination of CO2 Reforming and Partial Oxidation of Methane: Characterization and Deactivation Mechanism Investigation

    Directory of Open Access Journals (Sweden)

    Sufang He

    2015-01-01

    Full Text Available The performance of Ni/SiO2 catalyst in the process of combination of CO2 reforming and partial oxidation of methane to produce syngas was studied. The Ni/SiO2 catalysts were prepared by using incipient wetness impregnation method with nickel nitrate as a precursor and characterized by FT-IR, TG-DTA, UV-Raman, XRD, TEM, and H2-TPR. The metal nickel particles with the average size of 37.5 nm were highly dispersed over the catalyst, while the interaction between nickel particles and SiO2 support is relatively weak. The weak NiO-SiO2 interaction disappeared after repeating oxidation-reduction-oxidation in the fluidized bed reactor at 700°C, which resulted in the sintering of metal nickel particles. As a result, a rapid deactivation of the Ni/SiO2 catalysts was observed in 2.5 h reaction on stream.

  11. In situ time-resolved FTIR investigation on the reaction mechanism of partial oxidation of methane to syngas over supported Rh and Ru catalysts

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In situ time-resolved FTIR spectroscopy was used to study the reaction mechanism of partial oxidation of methane (POM) to synthesis gas and the reaction of CH4/O2/He (2/1/45, molar ratio) gas mixture with adsorbed CO species over Rh/SiO2, Ru/γ-Al2O3 and Ru/SiO2 catalysts at 500-600℃. It was found that CO is the primary product of POM reaction over reduced and working state Rh/SiO2 catalysts. Direct oxidation of CH4 is the main pathway of synthesis gas formation over Rh/SiO2 catalyst. CO2 is the primary product of POM over Ru/γ-Al2O3 and Ru/SiO2 catalysts. The dominant reaction pathway for synthesis gas formation over Ru/γ-Al2O3 catalyst is via the reforming reactions of CH4 with CO2 and H2O. For the POM reaction over Rh/SiO2 and Ru/γ-Al2O3 catalysts, consecutive oxidation of surface CO species is an important pathway of CO2 formation.

  12. Partial inhibition of estrogen-induced mammary carcinogenesis in rats by tamoxifen: balance between oxidant stress and estrogen responsiveness.

    Directory of Open Access Journals (Sweden)

    Bhupendra Singh

    Full Text Available Epidemiological and experimental evidences strongly support the role of estrogens in breast tumor development. Both estrogen receptor (ER-dependent and ER-independent mechanisms are implicated in estrogen-induced breast carcinogenesis. Tamoxifen, a selective estrogen receptor modulator is widely used as chemoprotectant in human breast cancer. It binds to ERs and interferes with normal binding of estrogen to ERs. In the present study, we examined the effect of long-term tamoxifen treatment in the prevention of estrogen-induced breast cancer. Female ACI rats were treated with 17β-estradiol (E2, tamoxifen or with a combination of E2 and tamoxifen for eight months. Tissue levels of oxidative stress markers 8-iso-Prostane F(2α (8-isoPGF(2α, superoxide dismutase (SOD, glutathione peroxidase (GPx, catalase, and oxidative DNA damage marker 8-hydroxydeoxyguanosine (8-OHdG were quantified in the mammary tissues of all the treatment groups and compared with age-matched controls. Levels of tamoxifen metabolizing enzymes cytochrome P450s as well as estrogen responsive genes were also quantified. At necropsy, breast tumors were detected in 44% of rats co-treated with tamoxifen+E2. No tumors were detected in the sham or tamoxifen only treatment groups whereas in the E2 only treatment group, the tumor incidence was 82%. Co-treatment with tamoxifen decreased GPx and catalase levels; did not completely inhibit E2-mediated oxidative DNA damage and estrogen-responsive genes monoamine oxygenase B1 (MaoB1 and cell death inducing DFF45 like effector C (Cidec but differentially affected the levels of tamoxifen metabolizing enzymes. In summary, our studies suggest that although tamoxifen treatment inhibits estrogen-induced breast tumor development and increases the latency of tumor development, it does not completely abrogate breast tumor development in a rat model of estrogen-induced breast cancer. The inability of tamoxifen to completely inhibit E2-induced breast

  13. Gas-Phase Partial Oxidation of Lignin to Carboxylic Acids over Vanadium Pyrophosphate and Aluminum-Vanadium-Molybdenum.

    Science.gov (United States)

    Lotfi, Samira; Boffito, Daria C; Patience, Gregory S

    2015-10-26

    Lignin is a complex polymer that is a potential feedstock for aromatic compounds and carboxylic acids by cleaving the β-O-4 and 5-5' linkages. In this work, a syringe pump atomizes an alkaline solution of lignin into a catalytic fluidized bed operating above 600 K. The vanadium heterogeneous catalysts convert all the lignin into carboxylic acids (up to 25 % selectivity), coke, carbon oxides, and hydrogen. Aluminum-vanadium-molybdenum mostly produced lactic acid (together with formic acid, acrylic acid, and maleic anhydride), whereas the vanadium pyrophosphate catalyst produced more maleic anhydride. PMID:26361086

  14. Partial oxidation of methane to methanol with nitrogen dioxide in dielectric barrier discharge plasma: experimental and molecular modeling

    Science.gov (United States)

    Indarto, Antonius

    2016-04-01

    Non-catalytic conversion of methane (CH4) and nitrogen dioxide (NO2) into methanol (CH3OH) has been conducted and presented in this paper. Experiments were carried out using dielectric barrier discharge as the reaction medium in atmospheric pressure and temperature conditions. High yield production of methanol was achieved (18-20% mol) by single-stage plasma reaction with maximum selectivity of 32% mol. Compared to other oxidants, such as O2, the presence of NO2 in the plasma reaction resulted in higher methanol selectivity. For better understanding of the reactions, density functional theory calculations were also performed and discussed.

  15. Anchoring Tri(8-QuinolinolatoIron Onto Sba-15 for Partial Oxidation of Benzyl Alcohol Using Water as the Solvent

    Directory of Open Access Journals (Sweden)

    Yang Xiaoyuan

    2014-09-01

    Full Text Available Tri(8-quinolinolatoiron complex immobilized onto SBA-15 catalyst has been synthesized through a stepwise procedure. The characterization results indicated that the BET surface area, total pore volume and average pore width decrease after stepwise modification of SBA-15, while the structure keeps intact. Catalytic tests showed that FeQ3-SBA-15 catalyzes the oxidation reaction well with 34.8% conversion of benzyl alcohol and 74.7% selectivity to benzaldehyde when water is used as the solvent after 1 h reaction. In addition, homogeneous catalyst tri(8-quinolinolatoiron exhibits very bad catalytic behavior using water as the solvent.

  16. Rf-sputtered vanadium oxide thin films: effect of oxygen partial pressure on structural and electrochemical properties

    CERN Document Server

    Park, Y J; Ryu, K S; Chang, S H; Park, S C; Yoon, S M; Kim, D K

    2001-01-01

    Vanadium oxide thin films with thickness of about 2000 A have been prepared by radio frequency sputter deposition using a V sub 2 O sub 5 target in a mixed argon and oxygen atmosphere with different Ar/O sub 2 ratio ranging from 99/1 to 90/10. X-ray diffraction and X-ray absorption near edge structure spectroscopic studies show that the oxygen content higher than 5% crystallizes a stoichiometric V sub O sub 5 phase, while oxygen deficient phase is formed in the lower oxygen content. The oxygen content in the mixed Ar + O sub 2 has a significant influence on electrochemical lithium insertion/deinsertion property. The discharge-charge capacity of vanadium oxide film increases with increasing the reactive oxygen content. The V sub O sub 5 film deposited at the Ar/O sub 2 ratio of 90/10 exhibits high discharge capacity of 100 mu Ah/cm sup 2 -mu m along with good cycle performance.

  17. Fischer-Tropsch synthesis: Moessbauer studies of pretreated ultrafine iron oxide catalysts. Partial quarterly progress report, April--June 1992

    Energy Technology Data Exchange (ETDEWEB)

    Chenshi Huang; Davis, B.H. [Kentucky Univ., Lexington, KY (United States). Center for Applied Energy Research; Rao, K.R.P.M.; Huffman, G.P.; Huggins, F.E. [Kentucky Univ., Lexington, KY (United States). Inst. for Mining and Minerals Research

    1992-09-01

    Moessbauer spectroscopy indicates that a 24 hour-pretreatment in CO at 260{degrees}C and 8 atm. in a tetralin solvent almost completely converts uftrafine iron oxide (about 3 nm) to iron carbide. However, pretreatment in hydrogen under the same conditions resulted in reduction of about 33% of the iron to metallic Fe; the remainder was Fe{sub 3}O{sub 4}. Exposure of the CO pretreated catalyst to a 1:1 HDCO synthesis gas resulted in the gradual reoxidation of the carbides to Fe{sub 3}O{sub 4}. During the first 2 hours of exposure of the H{sub 2} pretreated sample to synthesis gas,.the metallic Fe was converted to iron carbides. Further exposure of the H{sub 2} pretreatment sample to synthesis gas did not result in a composition change of the catalyst. Therefore, it is concluded that iron carbides with different oxidation characteristics were formed in these two cases.

  18. SNPs in DNA repair or oxidative stress genes and late subcutaneous fibrosis in patients following single shot partial breast irradiation

    Directory of Open Access Journals (Sweden)

    Falvo Elisabetta

    2012-01-01

    Full Text Available Abstract Background The aim of this study was to evaluate the potential association between single nucleotide polymorphisms related response to radiotherapy injury, such as genes related to DNA repair or enzymes involved in anti-oxidative activities. The paper aims to identify marker genes able to predict an increased risk of late toxicity studying our group of patients who underwent a Single Shot 3D-CRT PBI (SSPBI after BCS (breast conserving surgery. Methods A total of 57 breast cancer patients who underwent SSPBI were genotyped for SNPs (single nucleotide polymorphisms in XRCC1, XRCC3, GST and RAD51 by Pyrosequencing technology. Univariate analysis (ORs and 95% CI was performed to correlate SNPs with the risk of developing ≥ G2 fibrosis or fat necrosis. Results A higher significant risk of developing ≥ G2 fibrosis or fat necrosis in patients with: polymorphic variant GSTP1 (Ile105Val (OR = 2.9; 95%CI, 0.88-10.14, p = 0.047. Conclusions The presence of some SNPs involved in DNA repair or response to oxidative stress seem to be able to predict late toxicity. Trial Registration ClinicalTrials.gov: NCT01316328

  19. Modulatory effects of nitric oxide-active drugs on the anticonvulsant activity of lamotrigine in an experimental model of partial complex epilepsy in the rat

    Directory of Open Access Journals (Sweden)

    Ferraro Giuseppe

    2007-07-01

    Full Text Available Abstract Background The effects induced by administering the anticonvulsant lamotrigine, the preferential inhibitor of neuronal nitric oxide synthase 7-nitroindazole and the precursor of NO synthesis L-arginine, alone or in combination, on an experimental model of partial complex seizures (maximal dentate gyrus activation were studied in urethane anaesthetized rats. The epileptic activity of the dentate gyrus was obtained through the repetitive stimulation of the angular bundle and maximal dentate gyrus activation latency, duration and post-stimulus afterdischarge duration were evaluated. Results Either Lamotrigine (10 mg kg-1 or 7-nitroindazole (75 mg kg-1 i.p. administration had an anticonvulsant effect, significantly reducing the number of animals responding to angular bundle stimulation. On the contrary, i.p. injection of L-arginine (1 g kg-1 induced an aggravation of the epileptiform phenomena, demonstrated by the significant augmentation of the duration of both maximal dentate activation and afterdischarge. Furthermore, the injection of lamotrigine and 7-nitroindazole in combination significantly increased the anticonvulsant effects induced by the same drugs separately, either reducing the number of responding animals or decreasing both maximal dentate gyrus activation and afterdischarge durations. On the contrary, the combined treatment with L-arginine and lamotrigine did not modify the maximal dentate gyrus activation parameters suggesting an adversative effect of L-arginine-increased nitric oxide levels on the lamotrigine-induced anticonvulsant action. Conclusion The present results indicate that the nitrergic neurotransmission exerts a significant modulatory role in the control of the development of paroxystic phenomena in the maximal dentate gyrus activation model of epilepsy. Finally, our data suggest a functional relationship between the nitric oxide system and the anticonvulsant effect of lamotrigine which could be enhanced by

  20. Proline-catalysed asymmetric ketol cyclizations: The template mechanism revisited

    Indian Academy of Sciences (India)

    R Malathi; D Rajagopal; Zoltan G Hajos; S Swaminathan

    2004-03-01

    A modified template mechanism based on modelling studies of energy minimised complexes is presented for the asymmetric proline-catalysed cyclization of triketones 1, 2 and 3 to the 2, 3-ketols 1a, 2a and 3a respectively. The template model involves a three-point contact as favoured in enzyme-substrate interactions. Our minimisation studies are in agreement with the divergent behaviour of the 6,5-, 6,6- and 6,7-bicyclic systems. They support the high 93.4% ee observed with the 6,5-bicyclic ketol and the lower 73% ee found with the 6,6-bicyclic ketol. The calculations also explain the lack of asymmetric induction with the 6,7-bicyclic system.

  1. Catalysed fusion: a very different book about CERN

    CERN Multimedia

    CERN Library

    2013-01-01

    Not many books get reviews resulting in headlines like "Steamy novel challenges CERN's serious image", "Love and death at CERN" and so on. But Francis Farley's book "Catalysed Fusion" does not leave its readers untouched.   Those of you who have been around some time will know Farley from when he worked at CERN. For "newcomers", Farley is a well-known physicist who put together the first experiment on the anomalous magnetic moment of the muon and has since taken part in all the experiments relating to this phenomenon. The back cover of his book reads: "A sizzling romance and a romp with subatomic particles at CERN. Love, discovery and adventure in the city where nations meet and beams collide. Life in a large laboratory. As always, the challenges are the same. Who leads? Who follows? Who succeeds? Who gets the credit? Who gets the women or the men? Young Jeremy arrives in CERN and joins the quest ...

  2. Phase-transfer-catalysed asymmetric synthesis of tetrasubstituted allenes

    Science.gov (United States)

    Hashimoto, Takuya; Sakata, Kazuki; Tamakuni, Fumiko; Dutton, Mark J.; Maruoka, Keiji

    2013-03-01

    Allenes are molecules based on three carbons connected by two cumulated carbon-carbon double bonds. Given their axially chiral nature and unique reactivity, substituted allenes have a variety of applications in organic chemistry as key synthetic intermediates and directly as part of biologically active compounds. Although the demands for these motivated many endeavours to make axially chiral, substituted allenes by exercising asymmetric catalysis, the catalytic asymmetric synthesis of fully substituted ones (tetrasubstituted allenes) remained largely an unsolved issue. The fundamental obstacle to solving this conundrum is the lack of a simple synthetic transformation that provides tetrasubstituted allenes in the action of catalysis. We report herein a strategy to overcome this issue by the use of a phase-transfer-catalysed asymmetric functionalization of 1-alkylallene-1,3-dicarboxylates with N-arylsulfonyl imines and benzylic and allylic bromides.

  3. Global network cooperation catalysed by a small prosocial migrant clique

    CERN Document Server

    Miller, Steve

    2016-01-01

    Much research has been carried out to understand the emergence of cooperation in simulated social networks of competing individuals. Such research typically implements a population as a single connected network. Here we adopt a more realistic premise; namely that populations consist of multiple networks, whose members migrate from one to another. Specifically, we isolate the key elements of the scenario where a minority of members from a cooperative network migrate to a network populated by defectors. Using the public goods game to model group-wise cooperation, we find that under certain circumstances, the concerted actions of a trivial number of such migrants will catalyse widespread behavioural change throughout an entire population. Such results support a wider argument: that the general presence of some form of disruption contributes to the emergence of cooperation in social networks, and consequently that simpler models may encode a determinism that precludes the emergence of cooperation.

  4. Cantilever stress measurements for pulsed laser deposition of perovskite oxides at 1000 K in an oxygen partial pressure of 10−4 millibars

    International Nuclear Information System (INIS)

    An in situ stress measurement setup using an optical 2-beam curvature technique is described which is compatible with the stringent growth conditions of pulsed laser deposition (PLD) of perovskite oxides, which involves high substrate temperatures of 1000 K and oxygen partial pressures of up to 1 × 10−4 millibars. The stress measurements are complemented by medium energy electron diffraction (MEED), Auger electron spectroscopy, and additional growth rate monitoring by a quartz microbalance. A shielded filament is used to allow for simultaneous stress and MEED measurements at high substrate temperatures. A computer-controlled mirror scans an excimer laser beam over a stationary PLD target. This avoids mechanical noise originating from rotating PLD targets, and the setup does not suffer from limited lifetime issues of ultra high vacuum (UHV) rotary feedthroughs

  5. In-Situ FT-IR Investigation of Partial Oxidation of Methane to Syngas over Rh/SiO2 Catalyst

    Institute of Scientific and Technical Information of China (English)

    Tinghua Wu; Dongmin Lin; Ying Wu; Xiaoping Zhou; Qiangu Yan; Weizheng Weng; Huilin Wan

    2007-01-01

    Partial oxidation of methane to syngas(POM)over Rh/SiO2 catalyst was investigated using in-situ FT-IR.when methane interacted with 1.0wt%Rh/SiO2 catalyst,it was dissociated to adsorbed hydrogen and CHx species.The adsorbed hydrogen atoms were transferred to SiO2 surface by "spill-over" and reacted with lattice oxygen to form surface-OH species.POM mechanism was investigated over Rh/SiO2 catalyst using in-situ FT-IR.It Was found that CO2 Was formed before CO could be detected when CH4 and O2 were introduced over the preoxidized Rh/SiO2 catalyst,whereas CO Was detected before CO2 Was formed over the prereduced Rh/SiO2 catalyst.

  6. Additive effects of alkaline-earth metals and nickel on the performance of Co/γ-Al2O3 in methane catalytic partial oxidation

    Institute of Scientific and Technical Information of China (English)

    Changlin Yu; Weizheng Weng; Qing Shu; Xiangjie Meng; Bin Zhang; Xirong Chen; Xiaochun Zhou

    2011-01-01

    Nano-sized γ-alumina(γ-Al2O3)was first prepared by a precipitation method.Then,active component of cobalt and a series of alkalineearth metal promoters or nickel(Ni)with different contents were loaded on the γ-Al2O3 support.The catalysts were characterized by N2 adsorption-desorption,X-ray diffraction(XRD)and thermogravimetry analysis(TGA).The activity and selectivity of the catalysts in catalytic partial oxidation(CPO)of methane have been compared with Co/γ-Al2O3,and it is found that the catalytic activity,selectivity,and stability are enhanced by the addition of alkaline-earth metals and nickel.The optimal loadings of strontium(Sr)and Ni were 6 and 4 wt%,respectively.This finding will be helpful in designing the trimetallic Co-Ni-Sr/γ-Al2O3 catalysts with high performance in CPO of methane.

  7. Cantilever stress measurements for pulsed laser deposition of perovskite oxides at 1000 K in an oxygen partial pressure of 10{sup −4} millibars

    Energy Technology Data Exchange (ETDEWEB)

    Premper, J.; Sander, D.; Kirschner, J. [Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle/Saale (Germany)

    2015-03-15

    An in situ stress measurement setup using an optical 2-beam curvature technique is described which is compatible with the stringent growth conditions of pulsed laser deposition (PLD) of perovskite oxides, which involves high substrate temperatures of 1000 K and oxygen partial pressures of up to 1 × 10{sup −4} millibars. The stress measurements are complemented by medium energy electron diffraction (MEED), Auger electron spectroscopy, and additional growth rate monitoring by a quartz microbalance. A shielded filament is used to allow for simultaneous stress and MEED measurements at high substrate temperatures. A computer-controlled mirror scans an excimer laser beam over a stationary PLD target. This avoids mechanical noise originating from rotating PLD targets, and the setup does not suffer from limited lifetime issues of ultra high vacuum (UHV) rotary feedthroughs.

  8. Synergetic effect of TeMo5O16 and MoO3 phases in MoTeOx catalysts used for the partial oxidation of propylene

    Institute of Scientific and Technical Information of China (English)

    Yiming He; Ying Wu; Weizheng Weng; Huilin Wan

    2011-01-01

    A detailed study on the synergetic effect of TeMo5O16 and MoO3 phases in the MoTeOx catalysts for the partial oxidation of propylene to acrolein has been reported in this work. It was found that both propylene conversion and acrolein selectivity increased with the addition of MoO3 to TeMo5O16. Based on the results of N2 adsorption-desorption, XRD, XPS, in-situ XRD, O2-TPO, and 2-propanol decomposition reaction, the higher catalytic performance and synergetic effect could be attributed to the enhancement of acidity and the oxygen transfer from TeMo5O16 to MoO3 phase.

  9. Habitual Coffee Consumption Does Not Correlate with Blood Pressure, Inflammation and Endothelial Dysfunction but Partially Correlates with Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Erizal Sugiono

    2013-04-01

    Full Text Available BACKGROUND: Coffee is the most widely consumed beverage in the world and has been known to have effects on cardiovascular system. Many researchers have examined the effects of coffee consumption on blood pressure (BP and risk of cardiovascular disease (CVD, but their results were inconsistent and still remain a subject of controversy. Oxidative stress, inflammation, and endothelial dysfunction have been known as risk factors of hypertension and CVD. Those factors are also known to be affected by coffee consumption. The aim of this study was to examine the relationship between the effects of habitual coffee consumption on BP and to examine the role of oxidative stress (F2 isoprostane, inflammation (high sensitive C-reactive protein (hsCRP and endothelial dysfunction (asymmetric dimethylarginine (ADMA. METHODS: This was a cross-sectional study in which 47 healthy, non-smoking men aged 30-60 years with varying coffee-drinking habits were enrolled. BP and blood/urine analysis of biomarkers were measured in the morning before activity. Coffee consumption was assessed using a questionnaire. The differences among variables were analyzed using ANOVA and the correlations between variables were analyzed using Kendall’s Tau correlation analysis. RESULTS: Habitual coffee consumption did not correlate with systolic/diastolic BP (r=-0.02; p=0.856 and r=0.15; p=0.230, respectively. Concentrations of ADMA and hsCRP were also not correlated with coffee consumption (r=0.03; p=0.764 and r=0.04; p=0.701, respectively. Coffee consumption only showed significant correlation with F2 isoprostane (r=0.34; p=0.004. CONCLUSIONS: BP was not affected by coffee consumption although coffee consumption has a significant correlation with F2 isoprostane. These findings suggest that correlation between coffee consumption and BP might be explained by other factors that were not included in this study. KEYWORDS: coffee, caffeine, cardiovascular disease, blood pressure, oxidative

  10. Poly(acrylic acid)-directed synthesis of colloidally stable single domain magnetite nanoparticles via partial oxidation

    Science.gov (United States)

    Altan, Cem L.; Gurten, Berna; Sadza, Roel; Yenigul, Elcin; Sommerdijk, Nico A. J. M.; Bucak, Seyda

    2016-10-01

    Octahedral, single domain magnetite nanoparticles with average size of ~55 nm were synthesized through oxidative aging of a ferrous hydroxide (Fe(OH)2) precursor at high pH in water. The synthesis was also carried out in the presence of the hydrophilic polymer poly(acrylic acid). Presence of the polymer changed the particle morphology from octahedral to spherical while average size decreased to 40-50 nm. Although these particles have a tendency to precipitate due to their high magnetic moment, dispersions of these particles were obtained in the presence of this particular polymer which made the particles stable in water for several days making them suitable for various biotechnological applications such as cell separation owing to their low toxicity.

  11. Evaluation of thermodynamic and kinetic stability of P-type transparent conducting oxide, SrCu2O2 under various oxygen partial pressures

    International Nuclear Information System (INIS)

    Highlights: ▶ Thermodynamic and kinetic stabilities of SrCu2O2 under various P(O2) was estimated. ▶ The reaction rate for decomposition decreased with decreasing temperature and P(O2). ▶ The activation energy for decomposition of SrCu2O2 was estimated to be 66 kJ/mol. ▶ SrCu2O2 showed less stability than those of other transparent p-type semiconductors. - Abstract: Kinetic stability of transparent p-type conducting oxide, SrCu2O2, has been evaluated by using X-ray diffraction measurement and thermogravimetry. It was revealed that SrCu2O2 decomposed to mixture of CuO and Sr14Cu24O41 in air at temperatures above 300 °C. The decomposition reaction rate can be successfully explained by kinetic model assuming first-order chemical reaction. The rate constant can be suppressed with decreasing temperature and oxygen partial pressure. The activation energy for decomposition reaction of SrCu2O2 calculated from Arrhenius plot was 66 kJ/mol, which was lower than those of other transparent p-type semiconductors such as CuAlO2 and CuGaO2. The low decomposition temperature and activation energy for decomposition indicate that chemical stability of SrCu2O2 is far lower than those of other p-type conducting oxides.

  12. BL153 Partially Prevents High-Fat Diet Induced Liver Damage Probably via Inhibition of Lipid Accumulation, Inflammation, and Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Jian Wang

    2014-01-01

    Full Text Available The present study was to investigate whether a magnolia extract, named BL153, can prevent obesity-induced liver damage and identify the possible protective mechanism. To this end, obese mice were induced by feeding with high fat diet (HFD, 60% kcal as fat and the age-matched control mice were fed with control diet (10% kcal as fat for 6 months. Simultaneously these mice were treated with or without BL153 daily at 3 dose levels (2.5, 5, and 10 mg/kg by gavage. HFD feeding significantly increased the body weight and the liver weight. Administration of BL153 significantly reduced the liver weight but without effects on body weight. As a critical step of the development of NAFLD, hepatic fibrosis was induced in the mice fed with HFD, shown by upregulating the expression of connective tissue growth factor and transforming growth factor beta 1, which were significantly attenuated by BL153 in a dose-dependent manner. Mechanism study revealed that BL153 significantly suppressed HFD induced hepatic lipid accumulation and oxidative stress and slightly prevented liver inflammation. These results suggest that HFD induced fibrosis in the liver can be prevented partially by BL153, probably due to reduction of hepatic lipid accumulation, inflammation and oxidative stress.

  13. Palladium-catalysed cyclisation of alkenols: Synthesis of oxaheterocycles as core intermediates of natural compounds

    Directory of Open Access Journals (Sweden)

    Miroslav Palík

    2014-09-01

    Full Text Available The study of Pd-catalysed cyclisation reactions of alkenols using different catalytic systems is reported. These transformations affect the stereoselective construction of mono- and/or bicyclic oxaheterocyclic derivatives depending on a starting alkenol. The substrate scope and proposed mechanism of Pd-catalysed cyclisation reactions are also discussed. Moreover, the diastereoselective Pd-catalysed cyclisation of appropriate alkenols to tetrahydrofurans and subsequent cyclisation provided properly substituted 2,5-dioxabicyclo[2.2.1]heptane and 2,6-dioxabicyclo[3.2.1]octane, respectively. Such bicyclic ring subunits are found in many natural products including ocellenynes and aurovertines.

  14. Experimental and numerical investigation of the catalytic partial oxidation of methane to synthesis gas for power generation applications[Dissertation 17183

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, A.

    2007-07-01

    The present work addresses the catalytic partial oxidation (CPO) of methane to synthesis gas, with particular emphasis on power generation applications. A combined experimental and numerical investigation of methane partial oxidation to synthesis gas (H{sub 2}, CO) over rhodium-based catalysts has been carried out at pressures of up to 10 bar. The reactivity of the produced hydrogen and the suitably-low light-off temperatures of the CPO reactor, greatly facilitate operation of power generation gas turbines with reduced NO{sub x} emissions, stable operation with low calorific value fuels, and new combustion strategies for efficient CO{sub 2} capture. Those strategies utilize CPO of methane with oxygen (separated from air) and large exhaust gas recycle (H{sub 2}O and CO{sub 2}). An optically accessible catalytic channel-flow reactor was used to carry out Raman spectroscopy of major gas-phase species and laser induced fluorescence (LIF) of formaldehyde, in order to gain fundamental information on the catalytic and gas-phase chemical pathways. Transverse concentration profiles measured by the spontaneous Raman scattering technique determined the catalytic reactivity, while the LIF provided flame shapes and anchoring positions that, in turn, characterized the gaseous reactivity. Comparison between measurements and 2-D CFD computations, led to the validation of detailed catalytic and gas-phase reaction mechanisms. Experiments in a subscale gas-turbine honeycomb catalytic reactor have shown that the foregoing reaction mechanisms were also appropriate under gas-turbine relevant conditions with short reactant residence times. The light-off behavior of the subscale honeycomb reactor was reproduced by transient 2-D CFD computations. Ignition and extinction in CPO was studied. It was shown that, despite the chemical impact of the H{sub 2}O diluent during the transient catalytic ignition event, the light-off times themselves were largely unaffected by the exhaust gas dilution

  15. Experimental and numerical investigation of the catalytic partial oxidation of methane to synthesis gas for power generation applications[Dissertation 17183

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, A.

    2007-07-01

    The present work addresses the catalytic partial oxidation (CPO) of methane to synthesis gas, with particular emphasis on power generation applications. A combined experimental and numerical investigation of methane partial oxidation to synthesis gas (H{sub 2}, CO) over rhodium-based catalysts has been carried out at pressures of up to 10 bar. The reactivity of the produced hydrogen and the suitably-low light-off temperatures of the CPO reactor, greatly facilitate operation of power generation gas turbines with reduced NO{sub x} emissions, stable operation with low calorific value fuels, and new combustion strategies for efficient CO{sub 2} capture. Those strategies utilize CPO of methane with oxygen (separated from air) and large exhaust gas recycle (H{sub 2}O and CO{sub 2}). An optically accessible catalytic channel-flow reactor was used to carry out Raman spectroscopy of major gas-phase species and laser induced fluorescence (LIF) of formaldehyde, in order to gain fundamental information on the catalytic and gas-phase chemical pathways. Transverse concentration profiles measured by the spontaneous Raman scattering technique determined the catalytic reactivity, while the LIF provided flame shapes and anchoring positions that, in turn, characterized the gaseous reactivity. Comparison between measurements and 2-D CFD computations, led to the validation of detailed catalytic and gas-phase reaction mechanisms. Experiments in a subscale gas-turbine honeycomb catalytic reactor have shown that the foregoing reaction mechanisms were also appropriate under gas-turbine relevant conditions with short reactant residence times. The light-off behavior of the subscale honeycomb reactor was reproduced by transient 2-D CFD computations. Ignition and extinction in CPO was studied. It was shown that, despite the chemical impact of the H{sub 2}O diluent during the transient catalytic ignition event, the light-off times themselves were largely unaffected by the exhaust gas dilution

  16. Epoxidation of olefins catalysed by vanadium-salan complexes: a theoretical mechanistic study.

    Science.gov (United States)

    Kuznetsov, Maxim L; Pessoa, João Costa

    2009-07-28

    Plausible mechanisms of olefin epoxidation catalysed by a V-salan model complex [VIV(=O)(L)(H2O)] (1, L=(CH2NHCH2CH=CHO-)2) in the presence of H2O2 are investigated and compared by theoretical methods using density functional theory. Three main routes, i.e. the Mimoun, Sharpless and biradical mechanisms, were examined in detail, and the Sharpless pathway was found to be the most favourable one. The reaction starts from the formation of an active catalytic species [VV(=O)(OO)(LH)] (3c) upon interaction of 1 with H2O2, then concerted, highly synchronous attack of the olefin to 3c occurs yielding the epoxide and catalyst [VV(=O)2(LH)], the latter being oxidized by H2O2 to 3c. The activation barrier strongly depends on the proton location in the catalyst molecule and is the lowest when one of the oxygen atoms of the salan ligand is protonated and the vanadium atom is penta-coordinated with one vacant coordination position (complex 3c). The olefin in this reaction acts as an electron donor (nucleophile) rather than as an electron acceptor (electrophile). PMID:19587988

  17. Effects of oxygen partial pressure and atomic oxygen on the microstructure of oxide scale of ZrB2–SiC composites at 1500 °C

    International Nuclear Information System (INIS)

    Highlights: •Effects of pressure on oxidation behaviour of ZrB2–SiC composites were investigated. •The response of ZrB2–SiC composites to atomic oxygen is assessed quantitatively. •The oxidation mechanism of ZrB2–SiC composites is analyzed in detail. -- Abstract: The oxidation behaviour of ZrB2-20 vol.% SiC composites was investigated based on the microstructural evolution of oxide scale under different oxygen partial pressures at 1500 °C, and the similar experiment was performed in atomic oxygen for comparison. The thickness of the oxide scale increases first and then gradually decreases as the pressure decreases, which is strongly dependent on both total pressure and oxygen partial pressure. The atomic oxygen significantly enhances the oxidation of ZrB2–SiC composites, but has little effect on the microstructure of oxide scale. The oxidation mechanism of ZrB2–SiC composites is also discussed in detail

  18. Copper-catalysed enantioselective stereodivergent synthesis of amino alcohols

    Science.gov (United States)

    Shi, Shi-Liang; Wong, Zackary L.; Buchwald, Stephen L.

    2016-04-01

    The chirality, or ‘handedness’, of a biologically active molecule can alter its physiological properties. Thus it is routine procedure in the drug discovery and development process to prepare and fully characterize all possible stereoisomers of a drug candidate for biological evaluation. Despite many advances in asymmetric synthesis, developing general and practical strategies for obtaining all possible stereoisomers of an organic compound that has multiple contiguous stereocentres remains a challenge. Here, we report a stereodivergent copper-based approach for the expeditious construction of amino alcohols with high levels of chemo-, regio-, diastereo- and enantioselectivity. Specifically, we synthesized these amino-alcohol products using sequential, copper-hydride-catalysed hydrosilylation and hydroamination of readily available enals and enones. This strategy provides a route to all possible stereoisomers of the amino-alcohol products, which contain up to three contiguous stereocentres. We leveraged catalyst control and stereospecificity simultaneously to attain exceptional control of the product stereochemistry. Beyond the immediate utility of this protocol, our strategy could inspire the development of methods that provide complete sets of stereoisomers for other valuable synthetic targets.

  19. Taille des particules et catalyse Particle Size and Catalysis

    Directory of Open Access Journals (Sweden)

    Boitiaux J. P.

    2006-11-01

    Full Text Available Si la catalyse hétérogène et notamment la catalyse par les métaux se préoccupe de la taille des particules et donc de la surface développée, ce n'est pas seulement pour élaborer un produit efficace à moindre coût. L'étude des relations entre les caractéristiques des catalyseurs et leurs propriétés vis-à-vis des réactions a permis d'arriver dans certains cas à une description quasi atomique du site actif spécifique de chaque réaction. Les approches de ce problème qu'ont eu les différents auteurs sont différentes : l'une a consisté à prendre en considération les propriétés cristallographiques des métaux massiques, l'autre à considérer que les petites particules n'ont ni les propriétés, ni la structure du métal massif. L'approche cristallographique a d'abord conduit à prendre en compte les paramètres des cristaux et à distinguer les différents atomes situés en coins, arêtes ou faces. Mais très vite on s'est rendu compte que les particules n'avaient pas les structures attendues. On s'est donc intéressé au calcul de l'énergie des particules considérées pour imaginer comment elles pouvaient se construire à partir d'un petit noyau. Ces calculs ne tenaient compte ni de l'atmosphère en contact avec la particule, ni de la présence d'un support, ni des perturbations apportées par la réaction. En effet selon la réaction étudiée, on a pu définir des réactions facilesou insensibles à la structure et des réactions exigeantesdont la vitesse intrinsèque varie avec la structure de surface. Beaucoup de travaux ont été effectués sur des monocristaux dont les surfaces exposées avaient des indices différents et d'autres ont tenté d'étudier ces relations avec des métaux supportés, avec tous les artefacts que cela pouvait amener. Il a été difficile de trouver une unité dans tous les résultats obtenus et ceci d'autant plus que les phénomènes d'auto empoisonnement par les réactifs (hydrocarbures ou

  20. Carbonylation of Ethene Catalysed by Pd(II-Phosphine Complexes

    Directory of Open Access Journals (Sweden)

    Gianni Cavinato

    2014-09-01

    Full Text Available This review deals with olefin carbonylation catalysed by Pd(II-phosphine complexes in protic solvents. In particular, the results obtained in the carbonylation with ethene are reviewed. After a short description of the basic concepts relevant to this catalysis, the review treats in greater details the influence of the bite angle, skeletal rigidity, electronic and steric bulk properties of the ligand on the formation of the products, which range from high molecular weight perfectly alternating polyketones to methyl propanoate. It is shown that the steric bulk plays a major role in directing the selectivity. Particular emphasis is given to the factors governing the very active and selective catalysis to methyl propanoate, including the mechanism of the catalytic cycles with diphosphine- and monophosphine-catalysts. A brief note on the synthesis of methyl propanoate using a “Lucite” type catalyst in ionic liquids is also illustrated. A chapter is dedicated to the carbonylation of olefins in aqueous reaction media. The nonalternating CO-ethene copolymerization is also treated.

  1. 'Impact hunters' catalyse cooperative hunting in two wild chimpanzee communities.

    Science.gov (United States)

    Gilby, Ian C; Machanda, Zarin P; Mjungu, Deus C; Rosen, Jeremiah; Muller, Martin N; Pusey, Anne E; Wrangham, Richard W

    2015-12-01

    Even when hunting in groups is mutually beneficial, it is unclear how communal hunts are initiated. If it is costly to be the only hunter, individuals should be reluctant to hunt unless others already are. We used 70 years of data from three communities to examine how male chimpanzees 'solve' this apparent collective action problem. The 'impact hunter' hypothesis proposes that group hunts are sometimes catalysed by certain individuals that hunt more readily than others. In two communities (Kasekela and Kanyawara), we identified a total of five males that exhibited high hunt participation rates for their age, and whose presence at an encounter with red colobus monkeys increased group hunting probability. Critically, these impact hunters were observed to hunt first more often than expected by chance. We argue that by hunting first, these males dilute prey defences and create opportunities for previously reluctant participants. This by-product mutualism can explain variation in group hunting rates within and between social groups. Hunting rates declined after the death of impact hunter FG in Kasekela and after impact hunter MS stopped hunting frequently in Kanyawara. There were no impact hunters in the third, smaller community (Mitumba), where, unlike the others, hunting probability increased with the number of females present at an encounter with prey. PMID:26503679

  2. An Improved Ni-Based Catalyst for Partial Oxidation of Methane to Syngas%在改进的Ni-基催化剂上的甲烷部分氧化制合成气反应

    Institute of Scientific and Technical Information of China (English)

    楚文玲; 杨维慎; 林励吾

    2002-01-01

    @@In the partial oxidation of methane (POM) to syngas, nickel-based catalysts can be quite practical because of their fast turnover rate, high activity and low cost[1]. But previous investigations have shown that nickel is more susceptible to coking and si

  3. Multimetallic catalysed cross-coupling of aryl bromides with aryl triflates

    Science.gov (United States)

    Ackerman, Laura K. G.; Lovell, Matthew M.; Weix, Daniel J.

    2015-08-01

    The advent of transition-metal catalysed strategies for forming new carbon-carbon bonds has revolutionized the field of organic chemistry, enabling the efficient synthesis of ligands, materials, and biologically active molecules. In cases where a single metal fails to promote a selective or efficient transformation, the synergistic cooperation of two distinct catalysts--multimetallic catalysis--can be used instead. Many important reactions rely on multimetallic catalysis, such as the Wacker oxidation of olefins and the Sonogashira coupling of alkynes with aryl halides, but this approach has largely been limited to the use of metals with distinct reactivities, with only one metal catalyst undergoing oxidative addition. Here, we demonstrate that cooperativity between two group 10 metal catalysts--(bipyridine)nickel and (1,3-bis(diphenylphosphino)propane)palladium--enables a general cross-Ullmann reaction (the cross-coupling of two different aryl electrophiles). Our method couples aryl bromides with aryl triflates directly, eliminating the use of arylmetal reagents and avoiding the challenge of differentiating between multiple carbon-hydrogen bonds that is required for direct arylation methods. Selectivity can be achieved without an excess of either substrate and originates from the orthogonal reactivity of the two catalysts and the relative stability of the two arylmetal intermediates. While (1,3-bis(diphenylphosphino)propane)palladium reacts preferentially with aryl triflates to afford a persistent intermediate, (bipyridine)nickel reacts preferentially with aryl bromides to form a transient, reactive intermediate. Although each catalyst forms less than 5 per cent cross-coupled product in isolation, together they are able to achieve a yield of up to 94 per cent. Our results reveal a new method for the synthesis of biaryls, heteroaryls, and dienes, as well as a general mechanism for the selective transfer of ligands between two metal catalysts. We anticipate that this

  4. Partial correction of sensitivity to oxidant stress in Friedreich ataxia patient fibroblasts by frataxin-encoding adeno-associated virus and lentivirus vectors.

    Science.gov (United States)

    Fleming, Jane; Spinoulas, Afroditi; Zheng, Maolin; Cunningham, Sharon C; Ginn, Samantha L; McQuilty, Robert C; Rowe, Peter B; Alexander, Ian E

    2005-08-01

    Peripheral nervous system (PNS) sensory neurons are directly involved in the pathophysiology of a number of debilitating inherited and acquired neurological conditions. The lack of effective treatments for many such conditions provides a strong rationale for exploring novel therapeutic approaches, including gene therapy. Friedreich ataxia (FRDA), a sensory neuropathy, is a progressive neurodegenerative disease associated with a loss of large sensory neurons from the dorsal root ganglia. Because a mouse model for this well-characterized disease has been generated, we elected to use FRDA as a model disease. In previous studies we achieved efficient and sustained delivery of a reporter gene to PNS sensory neurons, using recombinant adeno-associated viral (AAV) and lentiviral (LV) vectors. In the current study, AAV and LV vectors encoding the human frataxin cDNA were constructed and assessed for frataxin expression and function in primary FRDA patient fibroblast cell lines. FRDA fibroblasts have been shown to exhibit subtle biochemical changes, including increased mitochondrial iron and sensitivity to oxidant stress. Despite the inherent difficulty in working with primary cells, transduction of patient fibroblasts with either vector resulted in the expression of appropriately localized frataxin and partial reversal of phenotype.

  5. Partial oxidation of methane on Ni/CeO2-ZrO2/γ-Al2O3 prepared using different processes

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qingwei; SHEN Meiqing; WEN Jing; WANG Jun; FEI Yanan

    2008-01-01

    The influences of CeO2-ZrO2 and γ-Al2O3 mixing methods on the catalytic activity and stability of partial oxidation of methane (POM) were investigated over Ni/Ce0.7Zr0.3O2-Al2O3 catalysts. The catalysts were characterized by XRD, TPR, H2-chemsorption, and TG-DTA. For fresh catalysts, the results showed that the salt precursor mixing catalyst (ATOM) presented better performance than the catalysts prepared by the precipitator mixing method (MOL) and the powder mechanically mixing method (MECH). The result of XRD suggested that the interaction between CeO2-ZrO2 and Al2O3 in ATOM sample was stronger than the others, which led to more lattice defects and thereby better initial activity. Moreover, the MECH sample had the best stability and the least coke deposition in 24 h stability tests. The results of TPR and H2-chemsorption indicated that the intimate contact of Ni-Al in MECH sample enhanced the ability of resisting coke deposition and metal sintering.

  6. Role of Periodic Input Composition and Sweeping Gas for Improvement of Hydrogen Production in a Palladium Membrane Reactor by Partial Oxidation of Methane

    Institute of Scientific and Technical Information of China (English)

    Lemnouer Chibane; Brahim Djellouli

    2012-01-01

    The partial oxidation of methane under periodic operation over Ni/y/-Al2O3 catalyst was investigated in a Pd-membrane reactor. The effects of key parameters such as the inlet composition and the sweeping, gas on methane conversion and the hydrogen recovery are numerically estalallshed with two penodtc input ttmctlons. In order to analyze the effect of the inputs modulation, the reaction was performed under low steam to methane ratio at a mod-erate temperature and pressure. It was obtained that to achieve process intensification is to operate the process in a periodic way. The main results show that the periodic input functions can improve the performance of the process compared to the optimal steady state operation. Moreover, there is an optimum amplitude of manipulated inputs leads to a maximum of hydrogen recovery. It is noteworthy that the comparison between the predicted performancevia the sinusoidal and the'square ways show that the better'average performance was obtainedwith the square way.

  7. Experimental and modeling study of hydrogen/syngas production and particulate emissions from a natural gas-fueled partial oxidation engine

    International Nuclear Information System (INIS)

    In this study, a combustion model was first applied to conditions representing varying compression ratios and equivalence ratios to investigate engine exhaust composition from partial oxidation (POX) of natural gas in reciprocating engines. The model was experimentally validated over a range of equivalence ratios from 1.3 to 1.6 with a spark-ignited single cylinder engine fueled by natural gas. The modeling results matched well with engine gaseous emission data over the experimental range. The model was also extended to higher equivalence ratios to predict H2 and CO production at engine conditions and stoichiometries representative of homogeneous charge compression ignition (HCCI) engine operation. Secondly, over the same experimental range of equivalence ratios, particulate samples were taken to determine both total particulate mass production (g/hph) via gravimetric measurement as well as particle size distribution and loading via a scanning mobility particle sizer (SMPS). While experiments indicate hydrogen yields up to 11% using spark ignition (SI), modeling results indicate that greater than 20% H2 yield may be possible in HCCI operation. Over the experimental range, rich-burn particulate matter (PM) production is no greater than that from typical lean-burn operation. Finally, an energy balance was performed over the range of engine experimental operation. (author)

  8. Effect of calcination temperature and pretreatment with reaction gas on properties of Co/γ-Al2O3 catalysts for partial oxidation of methane.

    Science.gov (United States)

    Zhang, Nuo-Wei; Huang, Chuan-Jing; Zhu, Xiao-Quan; Xu, Jing-Dong; Weng, Wei-Zheng; Wan, Hui-Lin

    2012-08-01

    The effects of calcination temperature and feedstock pretreatment on the catalytic performance of Co/γ-Al(2)O(3) catalysts were studied for partial oxidation of methane (POM) to synthesis gas, with emphasis on the role of feedstock pretreatment. The physicochemical properties of the catalysts were characterized by N(2) adsorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), H(2) temperature-programmed reduction (H(2) -TPR), and Raman spectroscopy. The results showed that the pretreatment of the catalyst by reaction gas significantly improved the catalytic activity and stability for the POM reaction. On the other hand, the effect of calcination temperature was less significant. Although the initial activity was increased by an increased calcination temperature, the catalyst without the feedstock pretreatment suffered a rapid deactivation. The reaction-atmosphere pretreatment was revealed as a process that mainly modified the surface structure of the catalyst. In that process, the formation of a CoAl(2)O(4) -like compound led to high Co metal dispersion after reduction, and the transformation of the carrier into α-Al(2)O(3) occurred over the catalyst surface. Both the high dispersion of cobalt and the presence of α-Al(2)O(3) surface phase were assumed as the important factors resulting in an excellent catalytic performance in terms of high activity and high stability. PMID:22588989

  9. Synthesis gas production by methane partial oxidation on Ni Fe3O4-Ce0.75Zr0.25O2 catalysts: kinetic study

    Energy Technology Data Exchange (ETDEWEB)

    Sosa Vasquez, M.I.; Salinas Gutierrez, J.; Delgado Vigil, D.; Collins-Martinez, V.; Lopez Ortiz, A.

    2011-01-15

    FeCZ is an oxygen carrier material aimed to produce syngas through methane partial oxidation in absence of oxygen gas feed. This research studies the catalytic effect of Ni on FeCZ using an evaluation of the global kinetics (activation energy, reaction rate, order and constant) of its reaction with methane for syngas production. The kinetic study of this material is crucial to realistically determine the feasibility of a potential process and to provide better understanding of the influence of reaction conditions over the material and to help postulate a possible future reaction mechanism that fits the kinetic results of the process. The initial reaction rate was obtained from the slope of the linear region of the weight change signal as a function of time. Results indicate a first order global reaction rate for all materials. Activation energies for samples FeCZ, 0.05NiFeCZ and 2NiFeCZ were 52.2, 39.5 and 28.3 respectively, reflecting the catalytic effect of Ni over the FeCZ global reaction rate.

  10. Structural changes of noble metal catalysts during ignition and extinction of the partial oxidation of methane studied by advanced QEXAFS techniques

    DEFF Research Database (Denmark)

    Grunwaldt, Jan-Dierk; Beier, M.; Kimmerle, B.;

    2009-01-01

    Pt/Al2O3, the structural changes during ignition were significantly faster in the latter case. The rate of reduction of the catalyst during ignition was also dependent on the axial position in the fixed-bed. The spectroscopic results provide important insight into the ignition and extinction behavior......The dynamics of the ignition and extinction of the catalytic partial oxidation (CPO) of methane to hydrogen and carbon monoxide over Pt-Rh/Al2O3 and Pt/Al2O3 were studied in the subsecond timescale using quick-EXAFS with a novel cam-driven X-ray monochromator employing Si(111) and Si(311) crystals......-significantly faster than during the extinction of the reaction. The dynamic behavior of the catalysts was dependent on the flow conditions and the respective noble metal component(s). Higher reaction gas flow led to a faster ignition process. While the ignition over Pt-Rh/Al2O3 occurred at lower temperature than over...

  11. Effect of varying alveolar oxygen partial pressure on diffusing capacity for nitric oxide and carbon monoxide, membrane diffusing capacity and lung capillary blood volume.

    Science.gov (United States)

    Borland, C D; Cox, Y

    1991-12-01

    1. To examine the effect of varying oxygen partial pressure (PAO2) on nitric oxide (DLNO) and carbon monoxide (DLCO) diffusing capacity (transfer factor), 10 subjects performed combined DLCO/DLNO measurements with the inspired mixture made up with three different oxygen concentrations (25%, 18% and 15%) to give PAO2 values of 12-20 kPa. 2. A novel method is described for calculating membrane diffusing capacity (DM) and pulmonary capillary volume (Qc) from DLNO and DLCO. 3. The mean DMCO was 52.89 mmol min-1 kPa-1 and Qc was 0.056 litre. Reducing PAO2 from 20 to 12 kPa resulted in an increase in DLCO = -0.124 (O2%) + 11.67 (P less than 0.001) and a fall in DLNO = 0.538 (O2%) + 32.01 (P less than 0.001) and a fall in DLNO/DLCO = 0.107 (O2%) + 2.52 (P less than 0.001). DM (P = 0.59) and Qc (P = 0.64) also tended to fall with falling PAO2. 4. It appears more likely that the minor reduction in DLNO that we have observed with falling PAO2 is due to diffusion rather than reaction limitation.

  12. Adenoviral gene transfer of endothelial nitric-oxide synthase (eNOS) partially restores normal pulmonary arterial pressure in eNOS-deficient mice

    Science.gov (United States)

    Champion, Hunter C.; Bivalacqua, Trinity J.; Greenberg, Stanley S.; Giles, Thomas D.; Hyman, Albert L.; Kadowitz, Philip J.

    2002-01-01

    It has been shown that mice deficient in the gene coding for endothelial nitric-oxide synthase (eNOS) have increased pulmonary arterial pressure and pulmonary vascular resistance. In the present study, the effect of transfer to the lung of an adenoviral vector encoding the eNOS gene (AdCMVeNOS) on pulmonary arterial pressure and pulmonary vascular resistance was investigated in eNOS-deficient mice. One day after intratracheal administration of AdCMVeNOS to eNOS−/− mice, there was an increase in eNOS protein, cGMP levels, and calcium-dependent conversion of l-arginine to l-citrulline in the lung. The increase in eNOS protein and activity in eNOS−/− mice was associated with a reduction in mean pulmonary arterial pressure and pulmonary vascular resistance when compared with values in eNOS-deficient mice treated with vehicle or a control adenoviral vector coding for β-galactosidase, AdCMVβgal. These data suggest that in vivo gene transfer of eNOS to the lung in eNOS−/− mice can increase eNOS staining, eNOS protein, calcium-dependent NOS activity, and cGMP levels and partially restore pulmonary arterial pressure and pulmonary vascular resistance to near levels measured in eNOS+/+ mice. Thus, the major finding in this study is that in vivo gene transfer of eNOS to the lung in large part corrects a genetic deficiency resulting from eNOS deletion and may be a useful therapeutic intervention for the treatment of pulmonary hypertensive disorders in which eNOS activity is reduced. PMID:12237402

  13. Horseradish peroxidase-catalysed in situ-forming hydrogels for tissue-engineering applications.

    Science.gov (United States)

    Bae, Jin Woo; Choi, Jong Hoon; Lee, Yunki; Park, Ki Dong

    2015-11-01

    In situ-forming hydrogels are an attractive class of implantable biomaterials that are used for biomedical applications. These injectable hydrogels are versatile and provide a convenient platform for delivering cells and drugs via minimally invasive surgery. Although several crosslinking methods for preparing in situ forming hydrogels have been developed over the past two decades, most hydrogels are not sufficiently versatile for use in a wide variety of tissue-engineering applications. In recent years, enzyme-catalysed crosslinking approaches have been emerged as a new approach for developing in situ-forming hydrogels. In particular, the horseradish peroxidase (HRP)-catalysed crosslinking approach has received increasing interest, due to its highly improved and tunable capacity to obtain hydrogels with desirable properties. The HRP-catalysed crosslinking reaction immediately occurs upon mixing phenol-rich polymers with HRP and hydrogen peroxide (H2O2) in aqueous media. Based on this unique gel-forming feature, recent studies have shown that various properties of formed hydrogels, such as gelation time, stiffness and degradation rate, can be easily manipulated by varying the concentrations of HRP and H2O2. In this review, we outline the versatile properties of HRP-catalysed in situ-forming hydrogels, with a brief introduction to the crosslinking mechanisms involved. In addition, the recent biomedical applications of HRP-catalysed in situ-forming hydrogels for tissue regeneration are described.

  14. Metallaphotoredox-catalysed sp3-sp3 cross-coupling of carboxylic acids with alkyl halides

    Science.gov (United States)

    Johnston, Craig P.; Smith, Russell T.; Allmendinger, Simon; MacMillan, David W. C.

    2016-08-01

    In the past 50 years, cross-coupling reactions mediated by transition metals have changed the way in which complex organic molecules are synthesized. The predictable and chemoselective nature of these transformations has led to their widespread adoption across many areas of chemical research. However, the construction of a bond between two sp3-hybridized carbon atoms, a fundamental unit of organic chemistry, remains an important yet elusive objective for engineering cross-coupling reactions. In comparison to related procedures with sp2-hybridized species, the development of methods for sp3-sp3 bond formation via transition metal catalysis has been hampered historically by deleterious side-reactions, such as β-hydride elimination with palladium catalysis or the reluctance of alkyl halides to undergo oxidative addition. To address this issue, nickel-catalysed cross-coupling processes can be used to form sp3-sp3 bonds that utilize organometallic nucleophiles and alkyl electrophiles. In particular, the coupling of alkyl halides with pre-generated organozinc, Grignard and organoborane species has been used to furnish diverse molecular structures. However, the manipulations required to produce these activated structures is inefficient, leading to poor step- and atom-economies. Moreover, the operational difficulties associated with making and using these reactive coupling partners, and preserving them through a synthetic sequence, has hindered their widespread adoption. A generically useful sp3-sp3 coupling technology that uses bench-stable, native organic functional groups, without the need for pre-functionalization or substrate derivatization, would therefore be valuable. Here we demonstrate that the synergistic merger of photoredox and nickel catalysis enables the direct formation of sp3-sp3 bonds using only simple carboxylic acids and alkyl halides as the nucleophilic and electrophilic coupling partners, respectively. This metallaphotoredox protocol is suitable for

  15. Metallaphotoredox-catalysed sp(3)-sp(3) cross-coupling of carboxylic acids with alkyl halides.

    Science.gov (United States)

    Johnston, Craig P; Smith, Russell T; Allmendinger, Simon; MacMillan, David W C

    2016-08-18

    In the past 50 years, cross-coupling reactions mediated by transition metals have changed the way in which complex organic molecules are synthesized. The predictable and chemoselective nature of these transformations has led to their widespread adoption across many areas of chemical research. However, the construction of a bond between two sp(3)-hybridized carbon atoms, a fundamental unit of organic chemistry, remains an important yet elusive objective for engineering cross-coupling reactions. In comparison to related procedures with sp(2)-hybridized species, the development of methods for sp(3)-sp(3) bond formation via transition metal catalysis has been hampered historically by deleterious side-reactions, such as β-hydride elimination with palladium catalysis or the reluctance of alkyl halides to undergo oxidative addition. To address this issue, nickel-catalysed cross-coupling processes can be used to form sp(3)-sp(3) bonds that utilize organometallic nucleophiles and alkyl electrophiles. In particular, the coupling of alkyl halides with pre-generated organozinc, Grignard and organoborane species has been used to furnish diverse molecular structures. However, the manipulations required to produce these activated structures is inefficient, leading to poor step- and atom-economies. Moreover, the operational difficulties associated with making and using these reactive coupling partners, and preserving them through a synthetic sequence, has hindered their widespread adoption. A generically useful sp(3)-sp(3) coupling technology that uses bench-stable, native organic functional groups, without the need for pre-functionalization or substrate derivatization, would therefore be valuable. Here we demonstrate that the synergistic merger of photoredox and nickel catalysis enables the direct formation of sp(3)-sp(3) bonds using only simple carboxylic acids and alkyl halides as the nucleophilic and electrophilic coupling partners, respectively. This metallaphotoredox

  16. Hydrogen Production by Catalytic Partial Oxidation of Coke Oven Gas in BaCo0.7Fe0.3-xZrxO3-δ Ceramic Membrane Reactors

    Directory of Open Access Journals (Sweden)

    Yao Weilin

    2016-01-01

    Full Text Available The BaCo0.7Fe0.3-xZrxO3-δ (BCFZ, x = 0.04–0.12 mixed ionic–electronic conducting (MIEC membranes were synthesized with a sol–gel method and evaluated as potential membrane reactor materials for the partial oxidation of coke oven gas (COG. The effect of zirconium content on the phase structure, microstructure and performance of the BCFZ membrane under He or COG atmosphere were systemically investigated. The BaCo0.7Fe0.24Zr0.06O3-δ membrane exhibited the best oxygen permeability and good operation stability, which could be a potential candidate of the membrane materials for hydrogen production through the partial oxidation of COG.

  17. Thermodynamic Study on the Catalytic Partial Oxidation of Methane to Syngas%催化部分氧化甲烷制合成气的平衡热力学研究

    Institute of Scientific and Technical Information of China (English)

    徐健; 魏伟胜; 鲍晓军

    2002-01-01

    The catalytic partial oxidation of methane to syngas (CO+H2) has been simulated thermodynamically with the advanced process simulator PRO/Ⅱ. The influences of temperature, pressure, CH4/O2 ratio and steam addition in feed gas on the conversion of CH4 selectively to syngas and heat duty required were investigated, and their effects on carbon formation were also discussed. The simulation results were in good agreement with the literature data taken from a spouted bed reactor.

  18. Partial oxidation and CO{sub 2} reforming of methane on Pt/Al{sub 2}O{sub 3}, Pt/ZrO{sub 2}, and Pt/Ce-ZrO{sub 2} catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Mattos, L.V.; Noronha, F.B. [Instituto Nacional de Tecnologia-INT, Av. Venezuela 82, Rio de Janeiro CEP 20081-310 (Brazil); Rodino, E.; Passos, F.B. [Departamento de Engenharia Quimica e Programa de Pos-Graduacao em Quimica Organica, Universidade Federal Fluminense, Rua Passos da Patria, 156, Niteroi CEP 24210-230 (Brazil); Resasco, D.E. [School of Chemical Engineering and Materials Science, University of Oklahoma, 100 East Boyd Street, Norman, OK 73019 (United States)

    2003-09-15

    The partial oxidation and CO{sub 2} reforming of methane were studied on Pt/Al{sub 2}O{sub 3}, Pt/ZrO{sub 2}, and Pt/Ce-ZrO{sub 2} catalysts. The reducibility and the oxygen transfer capacity were evaluated by oxygen storage capacity (OSC). The effect of the support on the cleaning mechanism of the catalyst surface was investigated by the sequence of CH{sub 4}/O{sub 2} and CH{sub 4}/CO{sub 2} pulses. The Pt/Ce-ZrO{sub 2} catalyst showed the highest stability on both partial oxidation and CO{sub 2} reforming of methane. The results were explained by the higher reducibility and oxygen storage/release capacity of Pt/Ce-ZrO{sub 2} catalysts, which allowed a continuous removal of carbonaceous deposits from the active sites, favoring the stability of the catalysts, as revealed by the CH{sub 4}/O{sub 2} and CH{sub 4}/CO{sub 2} pulses. For Pt/Al{sub 2}O{sub 3} and Pt/ZrO{sub 2} catalysts, the increase of carbon deposits around or near the metal particle inhibits the CO{sub 2} dissociation on CO{sub 2} reforming of methane. This effect on the CO{sub 2} reforming of methane affects the partial oxidation of methane, which comprehends two steps: combustion of methane and CO{sub 2} and steam reforming of unreacted methane.

  19. Partial baroreceptor dysfunction and low plasma nitric oxide bioavailability as determinants of salt-sensitive hypertension: a reverse translational rat study

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez-Pérez, A.S.; López-Rodríguez, J.F.; Calvo-Turrubiartes, M.Z. [Integrative Physiology Laboratory, Department of Physiology and Biophysics, San Luis Potosí (Mexico); Saavedra-Alanís, V.M. [Molecular Biology Laboratory, Department of Biochemistry, San Luis Potosí (Mexico); Llamazares-Azuara, L. [Autonomous University of San Luis Potosí, Renal Laboratory, Faculty of Medicine, San Luis Potosí (Mexico); Rodríguez-Martínez, M. [Integrative Physiology Laboratory, Department of Physiology and Biophysics, San Luis Potosí (Mexico)

    2013-10-02

    This study determined whether clinical salt-sensitive hypertension (cSSHT) results from the interaction between partial arterial baroreceptor impairment and a high-sodium (HNa) diet. In three series (S-I, S-II, S-III), mean arterial pressure (MAP) of conscious male Wistar ChR003 rats was measured once before (pdMAP) and twice after either sham (SHM) or bilateral aortic denervation (AD), following 7 days on a low-sodium (LNa) diet (LNaMAP) and then 21 days on a HNa diet (HNaMAP). The roles of plasma nitric oxide bioavailability (pNOB), renal medullary superoxide anion production (RMSAP), and mRNA expression of NAD(P)H oxidase and superoxide dismutase were also assessed. In SHM (n=11) and AD (n=15) groups of S-I, LNaMAP-pdMAP was 10.5±2.1 vs 23±2.1 mmHg (P<0.001), and the salt-sensitivity index (SSi; HNaMAP−LNaMAP) was 6.0±1.9 vs 12.7±1.9 mmHg (P=0.03), respectively. In the SHM group, all rats were normotensive, and 36% were salt sensitive (SSi≥10 mmHg), whereas in the AD group ∼50% showed cSSHT. A 45% reduction in pNOB (P≤0.004) was observed in both groups in dietary transit. RMSAP increased in the AD group on both diets but more so on the HNa diet (S-II, P<0.03) than on the LNa diet (S-III, P<0.04). MAP modeling in rats without a renal hypertensive genotype indicated that the AD*HNa diet interaction (P=0.008) increases the likelihood of developing cSSHT. Translationally, these findings help to explain why subjects with clinical salt-sensitive normotension may transition to cSSHT.

  20. Influence of oxygen partial pressure on electrical properties of sintered oxide with spinel-type structure composed of Mn, Co, and Ni

    International Nuclear Information System (INIS)

    The effect of pO2 atmosphere during annealing on electrical properties of spinel-type oxide composed of Mn, Co, and Ni used as a thermistor material was investigated. Sintered body of monophase spinel-type oxide with composition of Mn1.5CoNi0.5O4 was prepared by oxidation and fired at 1400 deg C. Oxidation was conducted at 1100 deg C at which the spinel structure is stable. The spinel-type oxide was annealed in atmospheres of various pO2 in the temperature range 100 to 300 deg C. The oxide was p-type semiconductor regardless of annealing conditions. The electrical conductivity and the mobility increased with increasing pO2. Electrical conduction of the oxide was considered to be controlled by a small polaron hopping. Copyright (1998) Australasian Ceramic Society

  1. Unusual origins of isotope effects in enzyme-catalysed reactions

    OpenAIRE

    Northrop, Dexter B

    2006-01-01

    High hydrostatic pressure is a neglected tool for probing the origins of isotope effects. In chemical reactions, normal primary deuterium isotope effects (DIEs) arising solely from differences in zero point energies are unaffected by pressure; but some anomalous isotope effects in which hydrogen tunnelling is suspected are partially suppressed. In some enzymatic reactions, high pressure completely suppresses the DIE. We have now measured the effects of high pressure on the parallel 13C heavy ...

  2. Methane partial oxidation using FeO(x)@La(0.8)Sr(0.2)FeO(3-δ) core-shell catalyst--transient pulse studies.

    Science.gov (United States)

    Shafiefarhood, Arya; Hamill, Joseph Clay; Neal, Luke Michael; Li, Fanxing

    2015-12-14

    The chemical looping reforming (CLR) process, which utilizes a transition metal oxide based redox catalyst to partially oxidize methane to syngas, represents a potentially efficient approach for methane valorization. The CLR process inherently avoids costly cryogenic air separation by replacing gaseous oxygen with regenerable ionic oxygen (O(2-)) from the catalyst lattice. Our recent studies show that an Fe2O3@La0.8Sr0.2FeO3-δ core-shell redox catalyst is effective for CLR, as it combines the selectivity of an LSF shell with the oxygen capacity of an iron oxide core. The reaction between methane and the catalyst is also found to be highly dynamic, resulting from changes in lattice oxygen availability and surface properties. In this study, a transient pulse injection approach is used to investigate the mechanisms of methane partial oxidation over the Fe2O3@LSF redox catalyst. As confirmed by isotope exchange, the catalyst undergoes transitions between reaction "regions" with markedly different mechanisms. While oxygen evolution maintains a modified Mars-van Krevelen mechanism throughout the reaction with O(2-) conduction being the rate limiting step, the mechanism of methane conversion changes from an Eley-Rideal type in the first reaction region to a Langmuir-Hinshelwood-like mechanism in the third region. Availability of surface oxygen controls the reduction scheme of the catalyst and the underlying reaction mechanism.

  3. Methane partial oxidation using FeO(x)@La(0.8)Sr(0.2)FeO(3-δ) core-shell catalyst--transient pulse studies.

    Science.gov (United States)

    Shafiefarhood, Arya; Hamill, Joseph Clay; Neal, Luke Michael; Li, Fanxing

    2015-12-14

    The chemical looping reforming (CLR) process, which utilizes a transition metal oxide based redox catalyst to partially oxidize methane to syngas, represents a potentially efficient approach for methane valorization. The CLR process inherently avoids costly cryogenic air separation by replacing gaseous oxygen with regenerable ionic oxygen (O(2-)) from the catalyst lattice. Our recent studies show that an Fe2O3@La0.8Sr0.2FeO3-δ core-shell redox catalyst is effective for CLR, as it combines the selectivity of an LSF shell with the oxygen capacity of an iron oxide core. The reaction between methane and the catalyst is also found to be highly dynamic, resulting from changes in lattice oxygen availability and surface properties. In this study, a transient pulse injection approach is used to investigate the mechanisms of methane partial oxidation over the Fe2O3@LSF redox catalyst. As confirmed by isotope exchange, the catalyst undergoes transitions between reaction "regions" with markedly different mechanisms. While oxygen evolution maintains a modified Mars-van Krevelen mechanism throughout the reaction with O(2-) conduction being the rate limiting step, the mechanism of methane conversion changes from an Eley-Rideal type in the first reaction region to a Langmuir-Hinshelwood-like mechanism in the third region. Availability of surface oxygen controls the reduction scheme of the catalyst and the underlying reaction mechanism. PMID:26549423

  4. Catalytic oxidations by vanadium complexes

    OpenAIRE

    Ligtenbarg, A.G J; Hage, R.; Feringa, B. L.

    2003-01-01

    Vanadium haloperoxidases catalyse the oxidation of halides leading to halogenation of substrates or, in the absence of suitable substrates, to oxidation of hydrogen peroxide into singlet oxygen and water. Furthermore, V-haloperoxidases are capable to give enantioselective sulfoxidation under the appropriate conditions. The most interesting model compounds that have been synthesised and studied as bromination catalysts, and catalysts for, i.e. epoxidation, hydroxylation, sulfoxidation and alco...

  5. Biomimetic flavin-catalysed reactions for organic synthesis.

    Science.gov (United States)

    Iida, H; Imada, Y; Murahashi, S-I

    2015-07-28

    Using simple riboflavin related compounds as biomimetic catalysts, catalytic oxidation of various substrates with hydrogen peroxide or molecular oxygen can be performed selectively under mild conditions. The principle of these reactions is fundamental and will provide a wide scope for environmentally benign future practical methods.

  6. Selective synthesis of thiodiglycol dicarboxylic acid esters via -TsOH/C-catalysed direct esterification

    Indian Academy of Sciences (India)

    Dahong Jiang; Min Huang

    2012-09-01

    The esterification of thiodiglycol and long alkyl-chain carboxylic acids is reported. Reaction of thiodiglycol with carboxylic acid via -TsOH/C-catalysed direct esterification afforded thiodiglycol dicarboxylic acid esters in good yields and chemoselectivity. The use of immobilized -TsOH on activated carbon as catalyst is crucial for the transformation.

  7. NHC-catalysed diastereoselective synthesis of multifunctionalised piperidines via cascade reaction of enals with azalactones.

    Science.gov (United States)

    Singh, Atul K; Chawla, Ruchi; Rai, Ankita; Yadav, Lal Dhar S

    2012-04-18

    NHC-catalysed azalactone ring-opening and piperidine ring-closing cascade with α,β-unsaturated aldehydes (enals) in a one-pot operation is reported. The present reaction cascade offers a convenient method for a highly diastereoselective synthesis of multifunctionalised piperidines in excellent yields under mild conditions. PMID:22399056

  8. Lewis acidic metal catalysed organic transformations by designed multi-component structures and assemblies

    Indian Academy of Sciences (India)

    Afsar Ali; Amit P Singh; Rajeev Gupta

    2010-05-01

    This paper presents the recent developments in designing multi-component structures including metal-organic frameworks containing Lewis acidic metal ions. The emphasis has been given to understand the design elements adopted to synthesize such structures bearing Lewis acidic metal ion. Further, few important Lewis acidic metal catalysed organic transformation reactions have been discussed demonstrating the importance of such materials for practical purposes.

  9. Ancillary ligand-free copper catalysed hydrohydrazination of terminal alkynes with NH2NH2.

    Science.gov (United States)

    Peltier, Jesse L; Jazzar, Rodolphe; Melaimi, Mohand; Bertrand, Guy

    2016-02-14

    An efficient and selective Cu-catalysed hydrohydrazination of terminal alkynes with parent hydrazine is reported. The methodology tolerates a broad range of functional groups, allows for the synthesis of symmetrical and unsymmetrical azines, and can be extended to hydrazine derivatives and amines. PMID:26757745

  10. Francis Farley presenting his novel "Catalysed Fusion" in the CERN Library

    CERN Multimedia

    Farley, Irina

    2013-01-01

    "Catalysed Fusion" is described by its author Francis Farley, 92, as a "true-to-life fantasy woven around particle physics" set in 1980s Geneva – "the city where nations meet and particles collide". Farley presented the book in the program "Literature in Focus" on Tuesday 16th April 2013.

  11. Inactivation of barley limit dextrinase inhibitor by thioredoxin-catalysed disulfide reduction

    DEFF Research Database (Denmark)

    Jensen, Johanne Mørch; Hägglund, Per; Christensen, Hans Erik Mølager;

    2012-01-01

    Barley limit dextrinase (LD) that catalyses hydrolysis of α-1,6 glucosidic linkages in starch-derived dextrins is inhibited by limit dextrinase inhibitor (LDI) found in mature seeds. LDI belongs to the chloroform/methanol soluble protein family (CM-protein family) and has four disulfide bridges a...

  12. Radical C-H arylations of (hetero)arenes catalysed by gallic acid.

    Science.gov (United States)

    Perretti, Marcelle D; Monzón, Diego M; Crisóstomo, Fernando P; Martín, Víctor S; Carrillo, Romen

    2016-07-12

    Gallic acid efficiently catalyses radical arylations in water-acetone at room temperature. This methodology proved to be versatile and scalable. Therefore, it constitutes a greener alternative to arylation. Moreover, considering that gallic acid is an abundant vegetable tannin, this work also unleashes an alternative method for the reutilisation of bio-wastes. PMID:26804947

  13. Palladium-catalysed direct cross-coupling of secondary alkyllithium reagents

    NARCIS (Netherlands)

    Vila, Carlos; Giannerini, Massimo; Hornillos, Valentin; Fananas-Mastral, Martin; Feringa, Ben L.

    2014-01-01

    Palladium-catalysed cross-coupling of secondary C(sp(3)) organometallic reagents has been a long-standing challenge in organic synthesis, due to the problems associated with undesired isomerisation or the formation of reduction products. Based on our recently developed catalytic C-C bond formation w

  14. Monodentate phosphoramidites : A breakthrough in rhodium-catalysed asymmetric hydrogenation of olefins

    NARCIS (Netherlands)

    Berg, Michel van den; Minnaard, Adriaan J.; Haak, Robert M.; Leeman, Michel; Schudde, Ebe P.; Meetsma, Auke; de Vries, Andre H.M.; Maljaars, C. Elizabeth P.; Willans, Charlotte E.; Hyett, David; Boogers, Jeroen A.F.; Henderickx, Hubertus; Feringa, Ben L.

    2003-01-01

    Monodentate phosphoramidites based on BINOL or substituted BINOL are excellent ligands for the rhodium-catalysed asymmetric hydrogenation of olefins. Very high enantioselectivities were obtained with MonoPhos (7a) the simplest member of this class, a ligand that is prepared in a single step from BIN

  15. Mechanism and Stereoselectivity of Zeolite-catalysed Sugar Isomerisation in Alcohols

    DEFF Research Database (Denmark)

    Shunmugavel, Saravanamurugan; Riisager, Anders; Taarning, Esben;

    2016-01-01

    Glucose isomerisation to fructose can occur by different pathways and the mechanism of zeolite-catalysed glucose isomerisation in methanol has remained incompletely understood. Herein, the mechanism is studied using an 1H-13C HSQC NMR assay resolving different fructose isotopomers. We find that z...

  16. Ru-catalysed C-H silylation of unprotected gramines, tryptamines and their congeners.

    Science.gov (United States)

    Devaraj, K; Sollert, C; Juds, C; Gates, P J; Pilarski, L T

    2016-04-30

    Selective Ru-catalysed C2-H silylation of heteroarenes is presented. The transformation works with or without directing group assistance and requires no protecting groups. Gramines and tryptamines may be converted efficiently whilst avoiding deleterious elimination side-reactions. Mechanistic studies reveal an unusual activation of the indole C4-H bond by an electron-rich metal. PMID:27050747

  17. Amino acid-catalysed retroaldol condensation: The production of natural benzaldehyde and other flavour compounds

    NARCIS (Netherlands)

    Wolken, W.A.M.; Tramper, J.; Werf, M.J. van der

    2004-01-01

    The amino acid-catalysed retroaldol condensation previously described for citral has been extended to other α,β -unsaturated aldehydes. In the presence of glycine and an elevated pH, six other α,β-unsaturated aldehydes also underwent retroaldol condensation. Crotonaldehyde, as well as its proposed i

  18. Amino acid-catalysed retroaldol condensation: the production of natural benzaldehyde and other flavour compounds

    NARCIS (Netherlands)

    Wolken, W.A.M.; Tramper, J.; Werf, van der M.J.

    2004-01-01

    The amino acid-catalysed retroaldol condensation previously described for citral has been extended to other alpha,beta-unsaturated aldehydes. In the presence of glycine and an elevated pH, six other alpha,beta-unsaturated aldehydes also underwent retroaldol condensation. Crotonaldehyde, as well as i

  19. Amino acid-catalysed retroaldol condensation : the production of natural benzaldehyde and other flavour compounds

    NARCIS (Netherlands)

    Wolken, WAM; Tramper, J; van der Werf, MJ

    2004-01-01

    The amino acid-catalysed retroaldol condensation previously described for citral has been extended to other alpha,beta-unsaturated aldehydes. In the presence of glycine and an elevated pH, six other alpha,beta-unsaturated aldehydes also underwent retroaldol condensation. Crotonaldehyde, as well as i

  20. Comparison of LaFeO3, La0.8Sr0.2FeO3, and La0.8Sr0.2Fe0.9Co0.1O3 perovskite oxides as oxygen carrier for partial oxidation of methane

    Institute of Scientific and Technical Information of China (English)

    Xiaoping Dai; Changchun Yu; Qiong Wu

    2008-01-01

    Comparison of LaFeO3, La0.8Sr0.2FeO3, and La0.8Sr0.2Fe0.9Co0.1O3 perovskite oxides as oxygen cartier for partial oxidation of methane in the absence of gaseous oxygen was investigated by continuous flow reaction and sequential redox reaction. Methane was oxidized to syngas with high selectivity by oxygen species of perovskite oxides in the absence of gaseous oxygen. The sequential redox reaction revealed that the structural stability and continuous oxygen supply in redox re-action decreased over La0.8Sr0.2Fe0.9Co0.1O3 oxide, while LaFeO3 and Lao.sSro.2FeO3 exhibited excellent structural stability and continuous oxygen supply.

  1. Comparison of two different synthesis methods of perovskites, SrCo0.5FeO3 type, aiming at evaluating their use as membranes for partial oxidation of methane

    Directory of Open Access Journals (Sweden)

    Noronha F.B.

    2004-01-01

    Full Text Available In this work two different synthesis methods of perovskites, SrCo0.5FeO3, were compared: combustion synthesis and oxides mixture aiming at evaluating their use as membranes for partial oxidation of methane. The combustion synthesis method explores an exothermic, generally very fast and self-sustaining chemical reaction between the desired metal salts and a suitable organic fuel, which is ignited at a temperature much lower than the actual phase formation temperature. The oxides mixture are based on a physical mixture of the powder oxides followed by calcination to obtain the desired phase. In order to obtain the membranes, we studied the conformation of bodies and the temperatures of sintering in the two powders synthesized. The powders were analyzed by density and grain size distribution and characterized by X-ray diffraction (XRD and scanning electron microscopy (SEM. After conformation, in cylindrical form, the green bodies were analyzed by density. After sintering at 1150 °C, the membranes were analyzed by density and they were characterized by XRD and SEM. The powder obtained by combustion synthesis shows lower density and fine grains than the other obtained by oxides mixture. The membranes obtained present very different morphology depending on the precursor powder synthesis. The sintered membranes obtained by combustion method also present a very uniform morphology without segregation.

  2. Fenton Redox Chemistry: Arsenite Oxidation by Metallic Surfaces

    NARCIS (Netherlands)

    Borges Freitas, S.C.; Van Halem, D.; Badruzzaman, A.B.M.; Van der Meer, W.G.J.

    2014-01-01

    Pre-oxidation of As(III) is necessary in arsenic removal processes in order to increase its efficiency. Therefore, the Fenton Redox Chemistry is defined by catalytic activation of H2O2 and currently common used for its redox oxidative properties. In this study the effect of H2O2 production catalysed

  3. 温度对亚硝化及氧化亚氮释放的影响%Effect of temperature on ammoxidation and nitrous oxide emission in partial nitrification

    Institute of Scientific and Technical Information of China (English)

    郭宁; 张建; 孔强; 苗明升; 田琳

    2013-01-01

    To investigate the effect of temperature on partial nitrification and nitrous oxide emission in the process, batch experiments at different temperatures( 15℃ ,25℃ ,35℃) were conducted. The results indicated that temperature has important effect on partial nitrification and nitrous oxide emission in the process. In the range of 15 to 35℃ , ammoxidation percentage, nitrite accumulation rate and the emission of nitrous oxide rose with the temperature going up. 35℃ is the appropriate temperature for partial nitrification, the reason is that the average ammoxidation percentage is 50.9% , the nitrite accumulation rate is 55.6% and the ratio of NO2- -N to NH4+-N is 1. 1 at this temperature. The ammoxidation percentage and the ratio of NO2--N to NH4+-N at 35℃ were appropriate, so the partial nitrification can supply proper inflow to anaerobic ammonium oxidation. The average emission of N2O is higher which is 1.494 μg/g MLSS.%采用批次实验的方法探讨了3种不同温度(15℃,25℃,35℃)对亚硝化及其过程中温室气体氧化亚氮释放情况.结果表明,温度对亚硝化过程及氧化亚氮的释放有显著影响.在15~ 35℃范围内,随着温度的升高,氨氧化率和亚硝化积累率逐渐升高,N2O释放量也逐渐增大,35℃可以作为适宜的亚硝化温度,平均氨氧化率为50.9%,亚硝化积累率为55.6%,N,2--N与NH4+-N出水浓度比为1.1,氨氧化率,亚硝化积累率和出水中亚硝氮与氨氮浓度比较合适,从而可以为厌氧氨氧化工艺提供合适的进水,但在此温度下平均N2O释放量相对较高,为1.494 μg/g MLSS.

  4. Efficacy of nitric oxide, with or without continuing antihypertensive treatment, for management of high blood pressure in acute stroke (ENOS):a partial-factorial randomised controlled trial

    OpenAIRE

    Bath, Philip M. W.; Woodhouse, Lisa; Scutt, Polly; Krishnan, Kailash; Wardlaw, Joanna M; Bereczki, Daniel; Sprigg, Nikola; Berge, Eivind; Beridze, Maia; Caso, Valeria; Chen, Christopher; Christensen, Hanne; Collins, Ronan; El Etribi, Anwar; Laska, Ann Charlotte

    2015-01-01

    BACKGROUND: High blood pressure is associated with poor outcome after stroke. Whether blood pressure should be lowered early after stroke, and whether to continue or temporarily withdraw existing antihypertensive drugs, is not known. We assessed outcomes after stroke in patients given drugs to lower their blood pressure.METHODS: In our multicentre, partial-factorial trial, we randomly assigned patients admitted to hospital with an acute ischaemic or haemorrhagic stroke and raised systolic blo...

  5. A steric tethering approach enables palladium-catalysed C-H activation of primary amino alcohols

    Science.gov (United States)

    Calleja, Jonas; Pla, Daniel; Gorman, Timothy W.; Domingo, Victoriano; Haffemayer, Benjamin; Gaunt, Matthew J.

    2015-12-01

    Aliphatic primary amines are a class of chemical feedstock essential to the synthesis of higher-order nitrogen-containing molecules, commonly found in biologically active compounds and pharmaceutical agents. New methods for the construction of complex amines remain a continuous challenge to synthetic chemists. Here, we outline a general palladium-catalysed strategy for the functionalization of aliphatic C-H bonds within amino alcohols, an important class of small molecule. Central to this strategy is the temporary conversion of catalytically incompatible primary amino alcohols into hindered secondary amines that are capable of undergoing a sterically promoted palladium-catalysed C-H activation. Furthermore, a hydrogen bond between amine and catalyst intensifies interactions around the palladium and orients the aliphatic amine substituents in an ideal geometry for C-H activation. This catalytic method directly transforms simple, easily accessible amines into highly substituted, functionally concentrated and structurally diverse products, and can streamline the synthesis of biologically important amine-containing molecules.

  6. Total syntheses of mitragynine, paynantheine and speciogynine via an enantioselective thiourea-catalysed Pictet-Spengler reaction

    NARCIS (Netherlands)

    I. P. Kerschgens; E. Claveau; M.J. Wanner; S. Ingemann; J.H. van Maarseveen; H. Hiemstra

    2012-01-01

    The pharmacologically interesting indole alkaloids (-)-mitragynine, (+)-paynantheine and (+)-speciogynine were synthesised in nine steps from 4-methoxytryptamine by a route featuring (i) an enantioselective thiourea-catalysed Pictet-Spengler reaction, providing the tetrahydro-β-carboline ring and (i

  7. Iron(III) porphyrin-catalysed oxidation reactions by -chloroperbenzoic acid: Nature of reactive intermediates

    Indian Academy of Sciences (India)

    A Agarwala; V Bagchi; D Bandyopadhyay

    2005-03-01

    The reaction of -chloroperbenzoic (-CPBA) acid with meso-tetrakis (pentafluorophenyl) porphynatoiron(III) chloride (F20TPPFe(III)Cl) has been studied in dichloromethane and acetonitrile medium at 25 ± 1° C. The reactive intermediates formed in this reaction have been quantitatively trapped by 2,4,6-tri -butylphenol (TTBP) in both the solvents. It has been observed that the kinetic plots of the formation of TTBP$^{\\bullet}$ radical in dichloromethane are all multiexponential, supporting the formation of more than one reactive intermediate in this solvent. In acetonitrile solvent the formation of TTBP$^{\\bullet}$ radical was however observed to be distinctly single exponential. Different kinds of reactive intermediates are proposed in these two solvents.

  8. Gold film-catalysed benzannulation by Microwave-Assisted, Continuous Flow Organic Synthesis (MACOS

    Directory of Open Access Journals (Sweden)

    Gjergji Shore

    2009-07-01

    Full Text Available Methodology has been developed for laying down a thin gold-on-silver film on the inner surface of glass capillaries for the purpose of catalysing benzannulation reactions. The cycloaddition precursors are flowed through these capillaries while the metal film is being heated to high temperatures using microwave irradiation. The transformation can be optimized rapidly, tolerates a wide number of functional groups, is highly regioselective, and proceeds in good to excellent conversion.

  9. Copper-catalysed intramolecular O-arylation: a simple and efficient method for benzoxazole synthesis.

    Science.gov (United States)

    Wu, Fengtian; Zhang, Jie; Wei, Qianbing; Liu, Ping; Xie, Jianwei; Jiang, Haojie; Dai, Bin

    2014-12-21

    A wide range of 2-substituted benzoxazoles can be efficiently synthesized from N-(2-iodo-/bromo-phenyl)benzamides, and even the less reactive N-(2-chlorophenyl)benzamides, via Cu-catalysed intramolecular coupling cyclization reactions using methyl 2-methoxybenzoate as the ligand under mild reaction conditions. In addition, the benzoxazoles can be easily prepared from the primary amides coupling with o-dihalobenzenes in a single step.

  10. The role of pellet thermal stability in reactor design for heterogeneously catalysed chemical reactions

    OpenAIRE

    Wijngaarden, R.J.; Westerterp, K.R.

    1992-01-01

    For exothermic fluid-phase reactions, a reactor which is cooled at the wall can exhibit multiplicity or parametric sensitivity. Moreover, for heterogeneously catalysed exothermic fluid-phase reactions, each of the catalytically active pellets in the reactor can exhibit multiplicity. Both forms of multiplicity can lead to thermal instability and as such have to be taken into account in reactor design. Here the effect of both instabilities is quantified. To this end, simple first-order kinetics...

  11. Metal-catalysed organic transformations in water: From bromination to polymerisation

    Indian Academy of Sciences (India)

    Manish Bhattacharjee; Braja N Patra

    2006-11-01

    Reaction of ,-unsaturated aromatic carboxylic acids with KBr and H2O2 in the presence of Na2MoO4$\\cdot$H2O in aqueous medium affords -bromo alkenes in high yields. Metallocene dichlorides, Cp2MCl2 (M = Ti, Zr, or V) catalyse polymerisation of olefins in aqueous medium to afford high molecular weight polymers with low molecular weight distribution.

  12. Total Synthesis of (±)-Paroxetine by Diastereoconvergent Cobalt-Catalysed Arylation

    OpenAIRE

    Despiau, Carole F; Dominey, Andrew P; Harrowven, David C.; Linclau, Bruno

    2014-01-01

    A total synthesis of paroxetine is reported, with a diastereoselective and diastereoconvergent cobalt-catalysed sp3–sp2 coupling reaction involving a 3-substituted 4-bromo-N-Boc-piperidine (Boc = tert-butoxycarbonyl) substrate as a key step. A 9:1 diastereoselectivity was obtained, while a control experiment involving a conformationally locked 3-substituted 4-bromo-tert-butyl cyclohexane ring proceeded with essentially complete stereoselectivity.

  13. [2+2+2] cycloaddition reactions involving allenes catalysed by rhodium

    OpenAIRE

    Haraburda, Ewelina

    2015-01-01

    The development of new chemical processes for the formation of carbon-carbon bonds is an important topic in organic chemistry. In particular, the transition metal catalysed [2+2+2] cycloaddition reaction is a highly efficient synthetic tool that allows six-membered polysubstituted carbo- and heterocyclic derivatives to be obtained in an atom economy process. Allenes are versatile substrates for cycloaddition reactions that provide a good reactivity profile together with the ability to increas...

  14. 钙钛矿型透氧膜及其在甲烷部分氧化中的应用%Progress in perovskite-type oxygen permeable membrane and its application in partial oxidation of methane

    Institute of Scientific and Technical Information of China (English)

    鲁辉; 张岩; 尹春玲

    2011-01-01

    钙钛矿型透氧陶瓷膜是同时具有氧离子和电子导电性的功能无机膜,在纯氧分离和甲烷部分氧化膜反应器中具有重要的潜在应用.介绍了钙钛矿型透氧陶瓷膜的氧渗透原理、膜材料的结构性能及其在甲烷部分氧化制合成气中的应用研究进展,并对透氧膜所面临的挑战进行了论述.%Perovskite-type oxygen permeable ceramic membrane is a functional inorganic membrane with oxygen ionic and electronic conductivity, and had potential application in oxygen separation and partial oxidation of methane to syngas. The oxygen permeation mechanism, structure and properties of perovskitetype ceramic membranes, as well as its application in partial oxidation of methane to syngas were reviewed. The opportunities and challenge to the perovskite-type oxygen permeable membranes were also outlined.

  15. Activity and Activity Coefficient of Iron Oxides in the Liquid FeO-Fe2O3-CaO-SiO2 Slag Systems at Intermediate Oxygen Partial Pressures

    Science.gov (United States)

    Henao, Hector M.; Itagaki, Kimio

    2007-10-01

    At present, there is a scarcity of data on the activities of iron oxides in the FeO-Fe2O3-CaO-SiO2 slag system at intermediate oxygen partial pressures and temperatures relevant to sulfide smelting and nonferrous metallurgy. The present study provides relevant data at temperatures between 1573 and 1673 K and partial pressures of oxygen between 10-9 and 10-4 atm. The experiments were carried out by equilibrating the slag in a CO-CO2 gas mixture in a platinum crucible, after which the phases of all the experimental samples, including the platinum foil, were analyzed by electron probe microanalysis (EPMA). Where only liquid phase or liquid phase and tridymite (SiO2) were observed, wet chemical analysis was used to determine the ratio of (mass pct Fe2+)/(mass pct Fe3+). Activity and activity coefficients for FeO (liquid) and FeO1.33 (solid) were calculated. Tendencies of the effect of the (CaO/SiO2) ratio, temperature, and oxygen partial pressure on these thermochemical quantities are discussed in this article.

  16. 复合绝缘材料热氧老化中局部放电特性的实验研究%Partial Discharge Characteristics Study of Composite Insulating Materials in Thermo Oxidative Ageing

    Institute of Scientific and Technical Information of China (English)

    高山; 贾勇勇; 杨景刚; 陶风波; 董金龙; 张国钢

    2016-01-01

    The partial discharge (PD) characteristics of SMC, BMC, GPO-3, and epoxy resin composite material before and after thermal oxidative ageing were studied. The dielectrical properties and partial discharge characteristics of four composite insulating materials before and after thermal oxidative ageing under different frequency voltages were compared and analyzed. The results show that with the increase of applied voltage, when the voltage attains or exceeds the partial discharge inception voltage, the four composite insulation materials show different PD characteristics and PRPD spectra evolution patterns. After ageing, the partial discharge inception voltage of four materials increases, and the discharge amplitude of PD varies with the increase of applied voltage, but the PD phase and discharge density change little. The common and difference of partial discharge of different materials under different operating conditions should be considered in the evaluation of insulating properties of materials.%对SMC、BMC、GPO-3、环氧树脂复合材料在热氧老化前后的局部放电特性进行研究,对比分析未老化和经过热氧老化的4种复合绝缘材料在不同工频电压下的介电特性和局部放电特性.结果表明:随着外施电压的升高,当达到或超过材料的局部放电起始电压后,4种复合绝缘材料呈现不同的局部放电特性和PRPD谱图演变规律;经过老化后4种材料的起始局部放电电压均有所提高,局部放电量随外施电压升高而呈现不同的变化规律,放电相位和放电密度变化较小.对于材料的绝缘性能评估应综合考虑不同材料在不同运行条件下局部放电的共性和差异.

  17. Improved selectivity for partial oxidation of methane to methanol in the presence of nitrite ions and BiVO4 photocatalyst.

    Science.gov (United States)

    Murcia-López, S; Villa, K; Andreu, T; Morante, J R

    2015-04-28

    Nitrite ions are shown to have significant influence on the selectivity of the photocatalytic oxidation of methane to methanol. An almost complete inhibition of undesired CO2 has been achieved with BiVO4 in the presence of a low concentration of nitrite, which might act both as a UV filter and as a hydroxyl radical scavenger. PMID:25815428

  18. Reversible, partial inactivation of plant betaine aldehyde dehydrogenase by betaine aldehyde: mechanism and possible physiological implications.

    Science.gov (United States)

    Zárate-Romero, Andrés; Murillo-Melo, Darío S; Mújica-Jiménez, Carlos; Montiel, Carmina; Muñoz-Clares, Rosario A

    2016-04-01

    In plants, the last step in the biosynthesis of the osmoprotectant glycine betaine (GB) is the NAD(+)-dependent oxidation of betaine aldehyde (BAL) catalysed by some aldehyde dehydrogenase (ALDH) 10 enzymes that exhibit betaine aldehyde dehydrogenase (BADH) activity. Given the irreversibility of the reaction, the short-term regulation of these enzymes is of great physiological relevance to avoid adverse decreases in the NAD(+):NADH ratio. In the present study, we report that the Spinacia oleracea BADH (SoBADH) is reversibly and partially inactivated by BAL in the absence of NAD(+)in a time- and concentration-dependent mode. Crystallographic evidence indicates that the non-essential Cys(450)(SoBADH numbering) forms a thiohemiacetal with BAL, totally blocking the productive binding of the aldehyde. It is of interest that, in contrast to Cys(450), the catalytic cysteine (Cys(291)) did not react with BAL in the absence of NAD(+) The trimethylammonium group of BAL binds in the same position in the inactivating or productive modes. Accordingly, BAL does not inactivate the C(450)SSoBADH mutant and the degree of inactivation of the A(441)I and A(441)C mutants corresponds to their very different abilities to bind the trimethylammonium group. Cys(450)and the neighbouring residues that participate in stabilizing the thiohemiacetal are strictly conserved in plant ALDH10 enzymes with proven or predicted BADH activity, suggesting that inactivation by BAL is their common feature. Under osmotic stress conditions, this novel partial and reversible covalent regulatory mechanism may contribute to preventing NAD(+)exhaustion, while still permitting the synthesis of high amounts of GB and avoiding the accumulation of the toxic BAL.

  19. Partial oxidation of Raffinate II and other mixtures of n-Butane and n-Butenes to maleic anhydride in a fixed-bed reactor

    OpenAIRE

    Brandstädter, Willi Michael

    2008-01-01

    The utilisation of the C4 streams of steamcrackers by converting raffinate II to maleic anhydride was studied. The oxidation reactions were investigated in a laboratory-scale fixed-bed reactor to determine reaction kinetics. The effects of pore diffusional resistance were investigated and explained. A two-dimensional pseudo-homogeneous reactor model was used for the simulation of a production-scale fixed-bed reactor. A flow scheme of the reactor section including a recycle was proposed.

  20. Pineapple by-product and canola oil as partial fat replacers in low-fat beef burger: Effects on oxidative stability, cholesterol content and fatty acid profile.

    Science.gov (United States)

    Selani, Miriam M; Shirado, Giovanna A N; Margiotta, Gregório B; Rasera, Mariana L; Marabesi, Amanda C; Piedade, Sonia M S; Contreras-Castillo, Carmen J; Canniatti-Brazaca, Solange G

    2016-05-01

    The effect of freeze-dried pineapple by-product and canola oil as fat replacers on the oxidative stability, cholesterol content and fatty acid profile of low-fat beef burgers was evaluated. Five treatments were performed: conventional (CN, 20% fat) and four low-fat formulations (10% fat): control (CT), pineapple by-product (PA), canola oil (CO), and pineapple by-product and canola oil (PC). Low-fat cooked burgers showed a mean cholesterol content reduction of 9.15% compared to the CN. Canola oil addition improved the fatty acid profile of the burgers, with increase in the polyunsaturated/saturated fatty acids ratio and decrease in the n-6/n-3 ratio, in the atherogenic and thrombogenic indexes. The oxidative stability of the burgers was affected by the vegetable oil addition. However, at the end of the storage time (120 days), malonaldehyde values of CO and PC were lower than the threshold for the consumer's acceptance. Canola oil, in combination with pineapple by-product, can be considered promising fat replacers in the development of healthier burgers.

  1. Identification of oxidation products of 5-aminosalicylic acid in faeces and the study of their formation in vitro

    DEFF Research Database (Denmark)

    Jensen, J.; Cornett, Claus; Olsen, C. E.;

    1993-01-01

    products of 5-ASA using H-1-NMR spectroscopy and mass spectrometry. Reactions carried out in vitro between 5-ASA and oxidants suggested to be present in the inflamed bowel verified that the hypochlorite-mediated oxidation of 5-ASA as well as the haemoglobin-catalysed H2O2-dependent oxidation of 5-ASA...

  2. Ni-doped (CeO2−δ)–YSZ mesoarchitectured with nanocrystalline framework: the effect of thermal treatment on structure, surface chemistry and catalytic properties in the partial oxidation of methane (CPOM)

    International Nuclear Information System (INIS)

    Ni-doped (CeO2−δ)–YSZ (5 mol% Ni oxide, 10 mol% ceria) mesoarchitectures (MA) with nanocrystalline framework have been synthesized by an original, facile and cheap approach based on Triton X100 nonionic surfactant as template and water as solvent at a strong basic pH value. Following the hydrothermal treatment under autogenous pressure (∼18 bars), Ni, Ce, Y, and Zr were well ordered as MA with nanocrystalline framework, assuring thermal stability. A comprehensive investigation of structure, texture, morphology, and surface chemistry was performed by means of a variety of complementary techniques (X-Ray Diffraction, XRD; Raman Spectroscopy, RS; Brunauer—Emmett—Teller, BET; Temperature—Programmed Reduction, TPR; Transmission Electron Microscopy, TEM and DF-STEM; X-ray Photoelectron Spectroscopy, XPS; Catalytic activity and selectivity). N2 sorption measurements highlighted that the mesoporous structure is formed at 600 °C and remains stable at 800 °C. At 900 °C, the MA collapses, favoring the formation of macropores. The XRD and Raman Spectroscopy of all samples showed the presence of a pure, single phase with fluorite-type structure. At 900 °C, an increased tetragonal distortion of the cubic lattice was observed. The surface chemistry probed by XPS exhibits a mixture of oxidation states (Ce3+ + Ce4+) with high percentage of Ce3+ valence state ∼35 % and (Ni3+ and Ni2+) oxidation states induced by the thermal treatment. These nanoparticles assembled into MA show high stability and selectivity over time in catalytic partial oxidation of methane (CPOM). These promising performances suggest an interesting prospect for introduction as anode within IT-SOFC assemblies.Graphical Abstract

  3. Ni-doped (CeO{sub 2−δ})–YSZ mesoarchitectured with nanocrystalline framework: the effect of thermal treatment on structure, surface chemistry and catalytic properties in the partial oxidation of methane (CPOM)

    Energy Technology Data Exchange (ETDEWEB)

    Somacescu, Simona, E-mail: ssimona@icf.ro [Romanian Academy, “Ilie Murgulescu” Institute of Physical Chemistry (Romania); Florea, Mihaela [University of Bucharest, Department of Organic Chemistry, Biochemistry and Catalysis, Faculty of Chemistry (Romania); Osiceanu, Petre; Calderon-Moreno, Jose Maria [Romanian Academy, “Ilie Murgulescu” Institute of Physical Chemistry (Romania); Ghica, Corneliu [National Institute of Materials Physics (Romania); Serra, Jose Manuel [Universidad Politécnica de Valencia - Consejo Superior de Investigaciones Científicas, Instituto de Tecnología Química (Spain)

    2015-11-15

    Ni-doped (CeO{sub 2−δ})–YSZ (5 mol% Ni oxide, 10 mol% ceria) mesoarchitectures (MA) with nanocrystalline framework have been synthesized by an original, facile and cheap approach based on Triton X100 nonionic surfactant as template and water as solvent at a strong basic pH value. Following the hydrothermal treatment under autogenous pressure (∼18 bars), Ni, Ce, Y, and Zr were well ordered as MA with nanocrystalline framework, assuring thermal stability. A comprehensive investigation of structure, texture, morphology, and surface chemistry was performed by means of a variety of complementary techniques (X-Ray Diffraction, XRD; Raman Spectroscopy, RS; Brunauer—Emmett—Teller, BET; Temperature—Programmed Reduction, TPR; Transmission Electron Microscopy, TEM and DF-STEM; X-ray Photoelectron Spectroscopy, XPS; Catalytic activity and selectivity). N{sub 2} sorption measurements highlighted that the mesoporous structure is formed at 600 °C and remains stable at 800 °C. At 900 °C, the MA collapses, favoring the formation of macropores. The XRD and Raman Spectroscopy of all samples showed the presence of a pure, single phase with fluorite-type structure. At 900 °C, an increased tetragonal distortion of the cubic lattice was observed. The surface chemistry probed by XPS exhibits a mixture of oxidation states (Ce{sup 3+} + Ce{sup 4+}) with high percentage of Ce{sup 3+} valence state ∼35 % and (Ni{sup 3+} and Ni{sup 2+}) oxidation states induced by the thermal treatment. These nanoparticles assembled into MA show high stability and selectivity over time in catalytic partial oxidation of methane (CPOM). These promising performances suggest an interesting prospect for introduction as anode within IT-SOFC assemblies.Graphical Abstract.

  4. Synthesis of asymmetric supramolecular compounds using a Ni(0) catalysed homo-coupling approach

    OpenAIRE

    Cassidy, Lynda; Horn, Sabine; Cleary, Laura; Halpin, Yvonne; Browne, Wesley R.; Vos, Johannes G.

    2009-01-01

    The synthesis and characterisation of a series of dinuclear ruthenium and osmium polypyridyl metal complexes based on the bridging ligands [5-(5'-bipyridin-2',2 ''-yl)-3-(pyridin-2-yl)]-1,2,4-triazole (Hpytr-bipy), 2,2 ''-bis(pyridin-2 '' yl)-5,5 ''-bis(pyridin-3 ''-yl) (bipy-bipy) and 5,5'-bis(pyridin-2 ''-yl)-3,3'-bis(1,2,4-triazole) (Hpytr-Hpytr) are reported. The dinuclear complexes have been synthesised via a Ni(0) catalysed cross-coupling reaction from brominated precursors. With this a...

  5. Lipase-catalysed transesterification of soya bean oil for biodiesel production during continuous batch operation.

    Science.gov (United States)

    Du, Wei; Xu, Yuanyuan; Liu, Dehua

    2003-10-01

    The effects of temperature, oil/alcohol molar ratio and by-product glycerol were studied during Lipozyme TL IM-catalysed continuous batch operation when short-chain alcohols were used as the acyl acceptor. In non-continuous batch operation, the optimal oil/alcohol ratio and temperature were 1:4 and 40-50 degrees C; however, during the continuous batch operation, the optimal oil/alcohol ratio and temperature were 1:1 and 30 degrees C; 95% of enzymic activity remained after 10 batches when isopropanol was adopted to remove by-product glycerol during repeated use of the lipase.

  6. Hypochlorite-induced oxidation of thiols

    DEFF Research Database (Denmark)

    Davies, Michael Jonathan; Hawkins, C L

    2000-01-01

    -molecular-weight thiols such as reduced glutathione (GSH), and sulfur-containing amino acids in proteins, are major targets for HOCl. Radicals have not generally been implicated as intermediates in thiol oxidation by HOCl, though there is considerable literature evidence for the involvement of radicals in the metal ion......-, thermal- or UV light-catalysed decomposition of sulfenyl or sulfonyl chlorides which are postulated intermediates in thiol oxidation. In this study we show that thiyl radicals are generated on reaction of a number of low-molecular-weight thiols with HOCl. With sub-stoichiometric amounts of HOCl, relative...... for the involvement of sulfenyl chlorides (RSCl) in the formation of these radicals, and studies with an authentic sulfenyl chloride have demonstrated that this compound readily decomposes in thermal-, metal-ion- or light-catalysed reactions to give thiyl radicals. The formation of thiyl radicals on oxidation...

  7. Catalysed fusion

    CERN Document Server

    Farley, Francis

    2012-01-01

    A sizzling romance and a romp with subatomic particles at CERN. Love, discovery and adventure in the city where nations meet and beams collide. Life in a large laboratory. As always, the challenges are the same. Who leads? Who follows? Who succeeds? Who gets the credit? Who gets the women or the men? Young Jeremy arrives in CERN and joins the quest for green energy. Coping with baffling jargon and manifold dangers, he is distracted by radioactive rats, lovely ladies and an unscrupulous rival. Full of doubts and hesitations, he falls for a dazzling Danish girl, who leads him astray. His brilliant idea leads to a discovery and a new route to cold fusion. But his personal life is scrambled. Does it bring fame or failure? Tragedy or triumph?

  8. Protein oxidation and ageing

    DEFF Research Database (Denmark)

    Linton, S; Davies, Michael Jonathan; Dean, R T

    2001-01-01

    of redox-active metal ions that could catalyse oxidant formation. As a result of this decrease in antioxidant defences, and increased rate of ROS formation, it is possible that the impact of ROS increases with age. ROS are known to oxidise biological macromolecules, with proteins an important target....... If the argument that the impact of ROS increases with age is true, then proteins would be expected to accumulate oxidised materials with age, and the rate of such accumulation should increase with time, reflecting impaired inefficiency of homeostasis. Here we review the evidence for the accumulation of oxidised......, or modified, extra- and intra-cellular proteins in vivo....

  9. Methanol Partial Oxidation on MoO3/SiO2 Catalysts: Application of Vibrational Spectroscopic Imaging Techniques in a High Throughput Operando Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Li, Guosheng; Hu, Dehong; Xia, Guanguang; Zhang, Z Conrad

    2009-06-09

    A novel prototype high throughput operando (OHT) reactor designed and built for catalyst screening and characterization is presented in this article. For the first time, this OHT reactor integrates Fourier Transformation infrared (FT-IR) imaging technique and Raman spectroscopy in operando conditions. Using a focal plane array (HgCdTe FPA, 128x128 pixels, and 1,675 Hz frame rate) detector for the FT-IR imaging system, we are able to simultaneously follow the catalyst activity and selectivity of all parallel reaction channels. Each set of image data has 16, 384 IR spectra with a spectral range of 900-4000 cm-1 in an 8 cm-1 resolution. It only takes 2-20 second, depending on signal to noise ratio, to collect a full image of all reaction channels. Results on reactant conversion and product selectivity are obtained from FT-IR spectral analysis. Six home-designed Raman probes, one for each reaction channel, are used for simultaneous collection of Raman spectra of all catalysts and possible reaction intermediates on the catalyst surface under real reaction environment. As a model system, methanol partial oxidation reaction on silica supported molybdenum oxide (MoO3/SiO2) catalysts under different reaction conditions has been studied to show the performance of the OHT reactor.

  10. Use of ESR and HPLC to follow the anaerobic reaction catalysed by lipoxygenases.

    Science.gov (United States)

    Brandicourt, Stéphanie; Nicolas, Jacques; Boussard, Aline; Riquet, Anne-Marie

    2015-02-01

    The measurement of the 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL) consumption by using ESR allows to follow the anaerobic reaction between linoleic acid (LH) and its 13-hydroperoxide (LOOH) catalysed by lipoxygenase. During this reaction, two types of radicals are initially obtained, alkyl (L) and alkoxyl (LO) radicals which formed two types of adducts (LT and OLT) with TEMPOL as characterised by HPLC. The stoichiometry of the adduct formation is two mole of TEMPOL consumed for one mole of LH and one mole of LOOH. Using ESR, the kinetic parameters and the mechanism of the anaerobic reaction have been determined at pH 6.5 for three different lipoxygenases, soybean, horse bean and wheat and compared to the values obtained at pH 9 for soybean lipoxygenase. Wheat lipoxygenase is very weakly active compared to the other enzymes. An uncompetitive inhibition of the anaerobic reaction catalysed by soybean and horse bean lipoxygenases was observed with 2,6-di-tert-butyl-4-methylphenol (BHT). PMID:25172715

  11. EDITORIAL: Catalysing progress Catalysing progress

    Science.gov (United States)

    Demming, Anna

    2010-01-01

    Examples of the merits of blue-sky research in the history of science are legion. The invention of the laser, celebrating its 50th anniversary this year, is an excellent example. When it was invented it was considered to be 'a solution waiting for a problem', and yet the level to which it has now infiltrated our day-to-day technological landscape speaks volumes. At the same time it is also true to say that the direction of research is also at times rightly influenced by the needs and concerns of the general public. Over recent years, growing concerns about the environment have had a noticeable effect on research in nanotechnology, motivating work on a range of topics from green nanomaterial synthesis [1] to high-efficiency solar cells [2] and hydrogen storage [3]. The impact of the world's energy consumption on the welfare of the planet is now an enduring and well founded concern. In the face of an instinctive reluctance to curtail habits of comfort and convenience and the appendages of culture and consumerism, research into renewable and more efficient energy sources seem an encouraging approach to alleviating an impending energy crisis. Fuel cells present one alternative to traditional combustion cells that have huge benefits in terms of the efficiency of energy conversion and the limited harmful emissions. In last week's issue of Nanotechnology, Chuan-Jian Zhong and colleagues at the State University of New York at Binghamton in the USA presented an overview of research on nanostructured catalysts in fuel cells [4]. The topical review includes insights into the interactions between nanoparticles and between nanoparticles and their substrate as well as control over the composition and nanostructure of catalysts. The review also serves to highlight how the flourishing of nanotechnology research has heralded great progress in the exploitation of catalysts with nanostructures ingeniously controlled to maximize surface area and optimize energetics for synthesis procedures. One man who was well aware of the role of nanostructured catalysts in the progress of material science research was the late Ulrich Gösele, director at the Max-Planck-Institut für Mikrostrukturphysik Halle, who passed away at the age of 60 on 8 November, 2009. Ulrich Gösele published over 750 papers of premium calibre research that have collectively been cited over 20,000 times. His research output includes a cornucopia of excellent work published in Nanotechnology, amongst which are a number of papers detailing the deft manipulation of nanocatalysts to control the quality and structure of nanomaterials [5-8]. Ulrich Gösele was a pioneer in nanoscience. In 1991, when the nanotechnology revolution was little more than a portentous rumble, he published a seminal report examining the effect of quantum confinement on the optical properties of silicon nanowires [9]. While we lament the loss to the community, we have much to celebrate in the insights his legacy has provided for the progress of materials science. It would be unwise to assume that science will or can ultimately advance in such a way as to allow ample means to indulge an unrestrained appetite for consumerism and energy consumption. As with most things, a balanced approach, considering solutions to the problem from many angles, seems sensible. Nonetheless, a browse through the latest literature leaves much cause for optimism for the positive role science can play in improving and sustaining our lifestyle. References [1] Mukherjee P, Roy M, Mandal B P, Dey G K, Mukherjee P K, Ghatak J, Tyagi A K and Kale S P 2008 Nanotechnology 19 075103 [2] Greenham N C and Grätzel M 2008 Nanotechnology 19 420201 [3] Vajo J, Pinkerton F and Stetson N 2009 Nanotechnology 20 200201 [4] Zhong C-J, Luo J, Fang B, Wanjala B N, Njoki P N, Loukrakpam R and Yin J 2010 Nanotechnology 21 062001 [5] Sivakov V A, Scholz A, Syrowatka F, Falk F, Gösele U and Christiansen S H 2009 Nanotechnology 20 405607 [6] Liu L, Lee W, Huang Z, Scholz R and Gösele U 2008 Nanotechnology 19 335604 [7] Fan H J et al 2006 Nanotechnology 17 S231-9 [8] Stelzner Th et al 2006 Nanotechnology 17 2895-8 [9] Lehmann V and Gösele U 1991 Appl. Phys. Lett. 58 856-8

  12. EDITORIAL: Catalysing progress Catalysing progress

    Science.gov (United States)

    Demming, Anna

    2010-01-01

    Examples of the merits of blue-sky research in the history of science are legion. The invention of the laser, celebrating its 50th anniversary this year, is an excellent example. When it was invented it was considered to be 'a solution waiting for a problem', and yet the level to which it has now infiltrated our day-to-day technological landscape speaks volumes. At the same time it is also true to say that the direction of research is also at times rightly influenced by the needs and concerns of the general public. Over recent years, growing concerns about the environment have had a noticeable effect on research in nanotechnology, motivating work on a range of topics from green nanomaterial synthesis [1] to high-efficiency solar cells [2] and hydrogen storage [3]. The impact of the world's energy consumption on the welfare of the planet is now an enduring and well founded concern. In the face of an instinctive reluctance to curtail habits of comfort and convenience and the appendages of culture and consumerism, research into renewable and more efficient energy sources seem an encouraging approach to alleviating an impending energy crisis. Fuel cells present one alternative to traditional combustion cells that have huge benefits in terms of the efficiency of energy conversion and the limited harmful emissions. In last week's issue of Nanotechnology, Chuan-Jian Zhong and colleagues at the State University of New York at Binghamton in the USA presented an overview of research on nanostructured catalysts in fuel cells [4]. The topical review includes insights into the interactions between nanoparticles and between nanoparticles and their substrate as well as control over the composition and nanostructure of catalysts. The review also serves to highlight how the flourishing of nanotechnology research has heralded great progress in the exploitation of catalysts with nanostructures ingeniously controlled to maximize surface area and optimize energetics for synthesis procedures. One man who was well aware of the role of nanostructured catalysts in the progress of material science research was the late Ulrich Gösele, director at the Max-Planck-Institut für Mikrostrukturphysik Halle, who passed away at the age of 60 on 8 November, 2009. Ulrich Gösele published over 750 papers of premium calibre research that have collectively been cited over 20,000 times. His research output includes a cornucopia of excellent work published in Nanotechnology, amongst which are a number of papers detailing the deft manipulation of nanocatalysts to control the quality and structure of nanomaterials [5-8]. Ulrich Gösele was a pioneer in nanoscience. In 1991, when the nanotechnology revolution was little more than a portentous rumble, he published a seminal report examining the effect of quantum confinement on the optical properties of silicon nanowires [9]. While we lament the loss to the community, we have much to celebrate in the insights his legacy has provided for the progress of materials science. It would be unwise to assume that science will or can ultimately advance in such a way as to allow ample means to indulge an unrestrained appetite for consumerism and energy consumption. As with most things, a balanced approach, considering solutions to the problem from many angles, seems sensible. Nonetheless, a browse through the latest literature leaves much cause for optimism for the positive role science can play in improving and sustaining our lifestyle. References [1] Mukherjee P, Roy M, Mandal B P, Dey G K, Mukherjee P K, Ghatak J, Tyagi A K and Kale S P 2008 Nanotechnology 19 075103 [2] Greenham N C and Grätzel M 2008 Nanotechnology 19 420201 [3] Vajo J, Pinkerton F and Stetson N 2009 Nanotechnology 20 200201 [4] Zhong C-J, Luo J, Fang B, Wanjala B N, Njoki P N, Loukrakpam R and Yin J 2010 Nanotechnology 21 062001 [5] Sivakov V A, Scholz A, Syrowatka F, Falk F, Gösele U and Christiansen S H 2009 Nanotechnology 20 405607 [6] Liu L, Lee W, Huang Z, Scholz R and Gösele U 2008 Nanotechnology 19 335604 [7] Fan H J et al 2006 Nanotechnology 1

  13. Gold-catalysed facile access to indene scaffolds via sequential C-H functionalization and 5-endo-dig carbocyclization.

    Science.gov (United States)

    Ma, Ben; Wu, Ziang; Huang, Ben; Liu, Lu; Zhang, Junliang

    2016-08-01

    A concise synthesis of functionalized indene derivatives via the gold(i)-catalysed cascade C-H functionalization/conia-ene type reaction of electron-rich aromatics with o-alkynylaryl α-diazoesters has been developed. In this transformation, the gold catalyst not only catalysed the formation of the zwitterionic intermediate via intermolecular C-H functionalization but promoted the subsequent intramolecular 5-endo-dig cyclization via activation of alkynes. The reaction is characterized by high chemo- and site-selectivity, readily available starting materials, nice functional-group tolerance and mild reaction conditions. PMID:27373228

  14. Exploring the atmospheric chemistry of O2SO3- and assessing the maximum turnover number of ion catalysed H2SO4 formation

    Directory of Open Access Journals (Sweden)

    H. Vehkamäki

    2012-11-01

    Full Text Available It has recently been demonstrated that the O2SO3− ion forms in the atmosphere as a natural consequence of ionizing radiation. Here, we present a density functional theory-based study of the reactions of O2SO3− with O3. The most important reactions are (a oxidation of O2SO3− to O3SO3− and (b cluster decomposition into SO3, O2 and O3−. The former reaction is highly exothermic and the nascent O3SO3− will rapidly decompose into SO4− and O2. If the origin of O2SO3− is SO2 oxidation by O3−, the latter reaction closes a catalytic cycle wherein SO2 is oxidized to SO3. The relative rates between the two major sinks for O2SO3− is assessed, thereby providing a measure of the maximum turnover number of ion catalysed SO2 oxidation, i.e. how many SO2 can be oxidized per free electron. The rate ratio between reactions (a and (b is significantly altered by the presence or absence of a single water molecule, but reaction (b is in general much more probable. Although we are unable to assess the overall importance of this cycle in the real atmosphere due to the unknown influence of CO2 and NOx, we roughly estimate that ion induced catalysis may contribute with several percent of H2SO4 levels in typical CO2 free and low NOx reaction chambers, e.g. the CLOUD chamber at CERN.

  15. Exploring the atmospheric chemistry of O2SO3− and assessing the maximum turnover number of ion-catalysed H2SO4 formation

    Directory of Open Access Journals (Sweden)

    N. Bork

    2013-04-01

    Full Text Available It has recently been demonstrated that the O2SO3− ion forms in the atmosphere as a natural consequence of ionizing radiation. Here, we present a density functional theory-based study of the reactions of O2SO3− with O3. The most important reactions are (a oxidation to O2SO3− and (b cluster decomposition into SO3, O2 and O3−. The former reaction is highly exothermic, and the nascent O2SO3− will rapidly decompose into SO4− and O2. If the origin of O2SO3− is SO2 oxidation by O3−, the latter reaction closes a catalytic cycle wherein SO2 is oxidized to SO3. The relative rate between the two major sinks for O2SO3− is assessed, thereby providing a measure of the maximum turnover number of ion-catalysed SO2 oxidation, i.e. how many SO2 can be oxidized per free electron. The rate ratio between reactions (a and (b is significantly altered by the presence or absence of a single water molecule, but reaction (b is in general much more probable. Although we are unable to assess the overall importance of this cycle in the real atmosphere due to the unknown influence of CO2 and NOx, we roughly estimate that ion-induced catalysis may contribute with several percent of H2SO4 levels in typical CO2-free and low NOx reaction chambers, e.g. the CLOUD chamber at CERN.

  16. Ni的化学态对甲烷部分氧化反应机理的影响:能学分析%Influence of Ni Chemical States on the Partial Oxidation Mechanism of Methane: An Energetics Analysis

    Institute of Scientific and Technical Information of China (English)

    夏文生; 常刚; 侯玉慧; 翁维正; 万惠霖

    2011-01-01

    采用键指数归一-平方势(UBI-QEP)法对不同化学态Ni上甲烷部分氧化反应中各可能基元步骤进行了能学计算研究.结果表明,反应的速度控制步骤与金属Ni的化学态有关.还原态Ni上CO形成的反应速度控制步骤为表面上CH3与O物种间的缔合,而带部分正电荷的Ni上CO形成的反应速度控制步骤则为甲烷氧助解离形成表面CHxO物种.还原态和带部分正电荷的Ni中心在表面上共存时,反应的速度控制步骤将取决于表面CH3形成与表面CH3、O物种缔合两反应间的竞争,其竞争的强弱涉及Ni的化学态.此外,反应活性中心向正电荷的Ni转化时,会导致表面C和O及H和H物种缔合的活化能显著降低,有利于CO、H2的形成,而表面CHx物种解离则变得不容易,表面积炭受到明显的抑制.%An energetics analysis of the possible elementary steps involved in the partial oxidation of methane (POM) over different chemical states of Ni was carried out using the unity bond index-quadratic exponential potential (UBI-QEP) method. The results show that the rate determining step for the partial oxidation mechanism of methane is related to the chemical state of the Ni. Over reduced Ni the rate determining step for CO formation is the association of surface CH3 species with surface O species. Over apartial positive charged Ni surface the rate determining step is that methane dissociates into the CHxO species with the assistance of oxygen. Over the reduced and partial positive charged Ni sites in coexistence, however, the rate determining step depends on the competition between the formation of surface CH3 species and the recombination of surface CH3 species with surface O species. This competition is related to the chemical states of the Ni sites. If the partial positive charged Ni sites are predominant on the surface, the recombination of surface C species with surface O species and the recombination of surface H atom species favor CO and H

  17. 氧分压对铟镓锌氧薄膜晶体管性能影响%Effect of oxygen partial pressure on the performance of indium gallium zinc oxide thin film transistor

    Institute of Scientific and Technical Information of China (English)

    孙建明; 周婷婷; 任庆荣; 胡合合; 陈宁; 宁策; 王路; 刘文渠; 李东升

    2016-01-01

    采用标准的液晶显示屏基板制备工艺制备出铟镓锌氧薄膜晶体管(IGZO-TFT),通过调节 IGZO 薄膜工艺中氧分压,研究不同氧分压对TFT器件电学性能的影响.实验结果表明,所有器件都展现出良好的电学特性,随着氧分压从10%增加到50%,TFT的阈值电压由0.5 V增加到2.2 V,而亚阈值摆幅没有发生变化.在栅极施加30 V偏压3600 s后,随着氧分压的增加,阈值电压向正向的漂移量由1 V增加到9 V.经过分析得出高氧分压的 IGZO-TFT器件中载流子浓度低,建立相同导电能力的沟道时所需要栅极电压会更大,阈值电压会增加.而在金属-绝缘层-半导体(MIS)结构中低载流子浓度会导致有源层能带弯曲的部分包含更多与电子陷阱相同的能态,栅介质层(GI)会俘获更多的电子,造成阈值电压漂移量较大的现象.%Indium gallium zinc oxide thin film transistors (IGZO-TFT)were fabricated with the stand-ard process of TFT-LCD arrays substrate.The effects of different oxygen partial pressure on IGZO-TFT performance were investigated by adj usting the oxygen partial pressure in IGZO film process.All devices showed good electrical properties.The threshold voltage of TFT was increased from 0.5 V to 2.2 V as the oxygen partial pressure was increased from 10% to 50%,whereas the sub-threshold swing had not changed.Applying a positive gate bias of 30 V for 3 600 s,with the increase of the oxy-gen partial pressure,the positive shift of threshold voltage of IGZO-TFT was increased from 1 V to 9 V.The carrier concentration in TFT with higher oxygen partial pressure is lower.So it requires high-er gate voltage for building the channel with the same conductive capability,and therefore the thresh-old voltage will be higher.In the Metal-Insulator-Semiconductor (MIS)structure,the lower carrier concentration leads electron accumulation layer to be thicker.There will be more energy states in band bending part of active layer which

  18. Enzymatic Synthesis of Enantiopure α- and β-Amino Acids by Phenylalanine Aminomutase-Catalysed Amination of Cinnamic Acid Derivatives

    NARCIS (Netherlands)

    Wu, Bian; Szymanski, Wiktor; Wietzes, Pieter; Wildeman, Stefaan de; Poelarends, Gerrit J.; Feringa, Ben L.; Janssen, Dick B.

    2009-01-01

    The phenylalanine aminomutase (PAM) from Taxus chinensis catalyses the conversion of alpha-phenylalanine to beta-phenylalanine, an important step in the biosynthesis of the N-benzoyl phenylisoserinoyl side-chain of the anticancer drug taxol. Mechanistic studies on PAM have suggested that (E)-cinnami

  19. Potash alum [KAl(SO4)2.12H2O] catalysed esterification of formylphenoxyaliphatic acids

    Indian Academy of Sciences (India)

    Ganesan Shunmugadhas Suresh Kumar; Sudalaiandi Kumaresan

    2012-07-01

    A convenient and clean procedure for esterification is reported. Direct condensation of formylphenoxyaliphatic acids with low to high boiling alcohols catalysed by potash alum gave moderate to good yields. This catalyst could be recovered and reused without substantial loss in its catalytic activity and the methodology could be used for a range of closely related substrates.

  20. Mg(ClO4)2 catalysed preparation of 1-amidoalkyl-2-naphthols under solvent-free conditions

    Indian Academy of Sciences (India)

    Mohammad Ali Amrollahi; Bi Bi Fatemeh Mirjalili; Hamideh Emtiazi

    2013-05-01

    A simple, efficient, and practical procedure for the synthesis of amidoalkyl naphthols via multicomponent one-pot reaction of 2-naphthol, aldehydes and amides catalysed by Mg(ClO4)2 is described in high yields. The present work offers several advantages such as high

  1. Selective preparation of terminal alkenes from aliphatic carboxylic acids by a palladium-catalysed decarbonylation-eliminiation reaction

    NARCIS (Netherlands)

    Notre, le J.E.L.; Scott, E.L.; Franssen, M.C.R.; Sanders, J.P.M.

    2010-01-01

    Trialkylamines were used as additives in the decarbonylation–elimination reaction catalysed by the combination of palladium(II) chloride and DPE-Phos. Aliphatic carboxylic acids were transformed at relatively low temperature into terminal alkenes in high yield and high selectivity, without the need

  2. Multicomponent click synthesis of potentially biologically active triazoles catalysed by copper nanoparticles on activated carbon in water

    OpenAIRE

    Alonso Valdés, Francisco; Moglie, Yanina; Radivoy, Gabriel; Yus Astiz, Miguel

    2011-01-01

    A variety of potentially biologically active 1,2,3-triazoles, derived from (–)-menthol, lactic acid, D-glucose, oestrone, cholesterol, and phenacetin, have been synthesised through the multicomponent alkyne-azide 1,3-dipolar cycloaddition catalysed by copper nanoparticles on activated carbon in neat water.

  3. Scope and limitations of chiral bis(oxazoline) ligands in the copper-catalysed asymmetric cyclopropanation of trisubstituted alkenes

    DEFF Research Database (Denmark)

    Østergaard, N.; Jensen, Jakob Feldthusen; Tanner, David Ackland

    2001-01-01

    A series of derivatives of 3-methyl-2-buten-1-ol has been used to test the scope and limitations of the copper-catalysed asymmetric cyclopropanation of trisubstituted alkenes by ethyl diazoacetate in the presence of C-2-symmetric bis(oxazoline) ligands. In the best case, a trans/cis ratio of 91...

  4. Enantioselective lipase-catalysed kinetic resolution of acyloxymethyl and ethoxycarbonylmethyl esters of 1,4-dihydroisonicotinic acid derivatives

    NARCIS (Netherlands)

    Sobolev, A.; Franssen, M.C.R.; Poikans, J.; Duburs, G.; Groot, de Æ.

    2002-01-01

    The lipase-catalysed kinetic resolution of four derivatives of 4-[(acyloxy)methyl] and 4-ethoxycarbonylmethyl 3-methyl 5-propyl 2,6-dimethyl-1,4-dihydro-3,4,5-pyridinetricarboxylates has been investigated. Whereas the enantioselectivity of lipases towards the acyloxymethyl derivatives was rather low

  5. Thin film devices used as oxygen partial pressure sensors

    Science.gov (United States)

    Canady, K. S.; Wortman, J. J.

    1970-01-01

    Electrical conductivity of zinc oxide films to be used in an oxygen partial pressure sensor is measured as a function of temperature, oxygen partial pressure, and other atmospheric constituents. Time response following partial pressure changes is studied as a function of temperature and environmental changes.

  6. Enantioselective construction of quaternary N-heterocycles by palladium-catalysed decarboxylative allylic alkylation of lactams

    KAUST Repository

    Behenna, Douglas C.

    2011-12-18

    The enantioselective synthesis of nitrogen-containing heterocycles (N-heterocycles) represents a substantial chemical research effort and resonates across numerous disciplines, including the total synthesis of natural products and medicinal chemistry. In this Article, we describe the highly enantioselective palladium-catalysed decarboxylative allylic alkylation of readily available lactams to form 3,3-disubstituted pyrrolidinones, piperidinones, caprolactams and structurally related lactams. Given the prevalence of quaternary N-heterocycles in biologically active alkaloids and pharmaceutical agents, we envisage that our method will provide a synthetic entry into the de novo asymmetric synthesis of such structures. As an entry for these investigations we demonstrate how the described catalysis affords enantiopure quaternary lactams that intercept synthetic intermediates previously used in the synthesis of the Aspidosperma alkaloids quebrachamine and rhazinilam, but that were previously only available by chiral auxiliary approaches or as racemic mixtures. © 2012 Macmillan Publishers Limited. All rights reserved.

  7. Vanillin formation from ferulic acid in Vanilla planifolia is catalysed by a single enzyme

    DEFF Research Database (Denmark)

    Gallage, Nethaji Janeshawari; Hansen, Esben Halkjær; Kannangara, Rubini Maya;

    2014-01-01

    Vanillin is a popular and valuable flavour compound. It is the key constituent of the natural vanilla flavour obtained from cured vanilla pods. Here we show that a single hydratase/lyase type enzyme designated vanillin synthase (VpVAN) catalyses direct conversion of ferulic acid and its glucoside...... into vanillin and its glucoside, respectively. The enzyme shows high sequence similarity to cysteine proteinases and is specific to the substitution pattern at the aromatic ring and does not metabolize caffeic acid and p-coumaric acid as demonstrated by coupled transcription/translation assays. VpVAN localizes......-glucosyltransferases result in vanillyl alcohol glucoside formation from endogenous ferulic acid. A gene encoding an enzyme showing 71% sequence identity to VpVAN was identified in another vanillin-producing plant species Glechoma hederacea and was also shown to be a vanillin synthase as demonstrated by transient expression...

  8. Synthesis of asymmetric supramolecular compounds using a Ni(0) catalysed homo-coupling approach.

    Science.gov (United States)

    Cassidy, Lynda; Horn, Sabine; Cleary, Laura; Halpin, Yvonne; Browne, Wesley R; Vos, Johannes G

    2009-05-28

    The synthesis and characterisation of a series of dinuclear ruthenium and osmium polypyridyl metal complexes based on the bridging ligands [5-(5'-bipyridin-2',2''-yl)-3-(pyridin-2-yl)]-1,2,4-triazole (Hpytr-bipy), 2,2'-bis(pyridin-2''yl)-5,5'-bis(pyridin-3''-yl) (bipy-bipy) and 5,5'-bis(pyridin-2''-yl)-3,3'-bis(1,2,4-triazole) (Hpytr-Hpytr) are reported. The dinuclear complexes have been synthesised via a Ni(0) catalysed cross-coupling reaction from brominated precursors. With this approach a mixture of three products is obtained, which are separated by chromatographic methods. The compounds obtained are characterised by elemental analysis, (1)H NMR, absorption and emission spectroscopy. The synthetic approach developed offers a new route to asymmetric multinuclear supramolecular structures that is complimentary to the complexes as ligands/complexes as metal approaches. PMID:19440590

  9. Enzyme catalysed production of sialylated human milk oligosaccharides and galactooligosaccharides by Trypanosoma cruzi trans-sialidase

    DEFF Research Database (Denmark)

    Holck, Jesper; Larsen, Dorte Møller; Michalak, Malwina;

    2014-01-01

    A Trypanosoma cruzi trans-sialidase (E.C. 3.2.1.18) was cloned into Pichia pastoris and expressed. The pH and temperature optimum of the enzyme was determined as pH 5.7 and 30°C. Using casein glycomacropeptide (CGMP) and lactose as sialyl-donor and acceptor respectively, the optimal donor....../acceptor ratio for the trans-sialidase catalysed 3′-sialyllactose production was found to be 1:4. Quantitative amounts of 3′-sialyllactose were produced from CGMP and lactose at a yield of 40mg/g CGMP. The 3′-sialyllactose obtained exerted a stimulatory effect on selected probiotic strains, including different...

  10. Production de biohydrogène par électro-catalyse microbienne

    OpenAIRE

    Rousseau, Raphaël

    2013-01-01

    La cellule d’électrolyse microbienne (CEM) permet la conversion de la biomasse en dihydrogène via un apport théorique en énergie électrique 10 fois moindre que celui de l’électrolyse de l’eau. Un tel procédé fonctionne via la technologie des bioanodes, qui permet la catalyse de l’oxydation de la biomasse en CO2 par l’intermédiaire d’un biofilm électro-actif. Les travaux exposés dans ce manuscrit de thèse ont pour but l’optimisation des performances de la bioanode, la compréhension des mécanis...

  11. On the Mechanism of the Digold(I)-Hydroxide-Catalysed Hydrophenoxylation of Alkynes

    KAUST Repository

    Gómez-Suárez, Adrián

    2015-12-13

    Herein, we present a detailed investigation of the mechanistic aspects of the dual gold-catalysed hydrophenoxylation of alkynes by both experimental and computational methods. The dissociation of [{Au(NHC)}2(μ-OH)][BF4] is essential to enter the catalytic cycle, and this step is favoured by the presence of bulky, non-coordinating counter ions. Moreover, in silico studies confirmed that phenol does not only act as a reactant, but also as a co-catalyst, lowering the energy barriers of several transition states. A gem-diaurated species might form during the reaction, but this lies deep within a potential energy well, and is likely to be an "off-cycle" rather than an "in-cycle" intermediate. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Catalytic Partial Oxidation of Methane with Air to Syngas in a Pilot-Plant-Scale Spouted Bed Reactor%甲烷空气部分氧化制合成气喷动床反应器的研究

    Institute of Scientific and Technical Information of China (English)

    魏伟胜; 徐建; 方大伟; 鲍晓军

    2003-01-01

    On the basis of hydrodynamic and scaling-up studies, a pilot-plant-scale thermal spouted bed reactor (50 mm in ID and 1500 mm in height) was designed and fabricated by scaling-down cold simulators. It was tested for making syngas via catalytic partial oxidation (CPO) of methane by air. The effects of various operating conditions such as operating pressure and temperature, feed composition, and gas fiowrate etc. on the CPO process were investigated. CH4 conversion of 92.2% and selectivity of 92.3% and 83.3% to CO and H2, respectively, were achieved at the pressure of 2.1 MPa. It was found that when the spouted bed reactor was operated within the stable spouting flow regime, the temperature profiles along the bed axis were much more uniform than those operated within the fixed-bed regime. The CH4 conversion and syngas selectivity were found to be close to thermodynamic equilibrium limits. The results of the present investigation showed that spouted bed could be considered as a potential type of chemical reactor for the CPO process of methane.

  13. Partial tooth gear bearings

    Science.gov (United States)

    Vranish, John M. (Inventor)

    2010-01-01

    A partial gear bearing including an upper half, comprising peak partial teeth, and a lower, or bottom, half, comprising valley partial teeth. The upper half also has an integrated roller section between each of the peak partial teeth with a radius equal to the gear pitch radius of the radially outwardly extending peak partial teeth. Conversely, the lower half has an integrated roller section between each of the valley half teeth with a radius also equal to the gear pitch radius of the peak partial teeth. The valley partial teeth extend radially inwardly from its roller section. The peak and valley partial teeth are exactly out of phase with each other, as are the roller sections of the upper and lower halves. Essentially, the end roller bearing of the typical gear bearing has been integrated into the normal gear tooth pattern.

  14. Essays on partial retirement

    OpenAIRE

    Kantarci, T.

    2012-01-01

    Abstract: The five essays in this dissertation address a range of topics in the micro-economic literature on partial retirement. The focus is on the labor market behavior of older age groups. The essays examine the economic and non-economic determinants of partial retirement behavior, the effect of partial retirement on retirement income and health, and the factors that could limit workers to participate in partial retirement. The analysis is mainly empirical and makes use of survey data on a...

  15. Thin film oxygen partial pressure sensor

    Science.gov (United States)

    Wortman, J. J.; Harrison, J. W.; Honbarrier, H. L.; Yen, J.

    1972-01-01

    The development is described of a laboratory model oxygen partial pressure sensor using a sputtered zinc oxide thin film. The film is operated at about 400 C through the use of a miniature silicon bar. Because of the unique resistance versus temperature relation of the silicon bar, control of the operational temperature is achieved by controlling the resistance. A circuit for accomplishing this is described. The response of sputtered zinc oxide films of various thicknesses to oxygen, nitrogen, argon, carbon dioxide, and water vapor caused a change in the film resistance. Over a large range, film conductance varied approximately as the square root of the oxygen partial pressure. The presence of water vapor in the gas stream caused a shift in the film conductance at a given oxygen partial pressure. A theoretical model is presented to explain the characteristic features of the zinc oxide response to oxygen.

  16. Evaluation of Partial Oxidation Reformer Emissions

    Energy Technology Data Exchange (ETDEWEB)

    Unnasch, Stefan; Fable, Scott; Waterland, Larry

    2006-01-06

    In this study, a gasoline fuel processor and an ethanol fuel processor were operated under conditions simulating both startup and normal operation. Emissions were measured before and after the AGB in order to quantify the effectiveness of the burner catalyst in controlling emissions. The emissions sampling system includes CEM for O2, CO2, CO, NOx, and THC. Also, integrated gas samples are collected in evacuated canisters for hydrocarbon speciation analysis via GC. This analysis yields the concentrations of the hydrocarbon species required for the California NMOG calculation. The PM concentration in the anode burner exhaust was measured through the placement of a filter in the exhaust stream. The emissions from vehicles with fully developed on board reformer systems were estimated.

  17. Electrically assisted partial oxidation of methane

    Energy Technology Data Exchange (ETDEWEB)

    Lesueur, H.; Czernichowski, A.; Chapelle, J. (Orleans Univ., 45 (France))

    1994-01-01

    CO + H[sub 2] synthesis gas is easily obtained from CH[sub 4] + CO[sub 2] mixtures in a new plasma reactor based on gliding discharges (GlidArc) at atmospheric pressure with a high efficiency. Preliminary trials performed in a laboratory reactor at 1.8-4.7 m[sup 3]h[sup -1] gas flow, CO[sub 2]/CH[sub 4] molar ratio of 0.55, 1.13 and 2.17, and up to 3 kW electric power are described. Results are compared with previous results obtained in a controlled arc. (author)

  18. Structural basis for cellobiose dehydrogenase action during oxidative cellulose degradation

    OpenAIRE

    Tan, Tien-Chye; Kracher, Daniel; Gandini, Rosaria; Sygmund, Christoph; Kittl, Roman; Haltrich, Dietmar; Hallberg, B Martin; Ludwig, Roland; Divne, Christina

    2015-01-01

    A new paradigm for cellulose depolymerization by fungi focuses on an oxidative mechanism involving cellobiose dehydrogenases (CDH) and copper-dependent lytic polysaccharide monooxygenases (LPMO); however, mechanistic studies have been hampered by the lack of structural information regarding CDH. CDH contains a haem-binding cytochrome (CYT) connected via a flexible linker to a flavin-dependent dehydrogenase (DH). Electrons are generated from cellobiose oxidation catalysed by DH and shuttled vi...

  19. Solid State Multinuclear NMR Studies of Nanostructured Thin Oxide Films%纳米结构氧化薄膜的固态多核核磁共振研究

    Institute of Scientific and Technical Information of China (English)

    O.Lapina

    2005-01-01

    @@ Knowledge of the structure of thin oxide films is very important for electrochemistry, microelectronics and catalyses. Supported oxide catalysts (supported thin oxide films) are used extensively in the petroleum, chemical and pollution control industries as catalysts for a wide range of chemically important transformations.

  20. In situ spectroscopic investigation of oxidative dehydrogenation and disproportionation of benzyl alcohol

    OpenAIRE

    Nowicka, E.; HOFMANN, J.P.; Parker, S. F.; Sankar, M.; Lari, G.M.; Kondrat, S.A.; Knight, D. W.; Bethell, D; Weckhuysen, B.M.; G. J. Hutchings

    2013-01-01

    In the solvent free oxidation of benzyl alcohol, using supported gold–palladium nanoalloys, toluene is often one of major by-products and it is formed by the disproportionation of benzyl alcohol. Gold–palladium catalysts on acidic supports promote both the disproportionation of benzyl alcohol and oxidative dehydrogenation to form benzaldehyde. Basic supports completely switch off disproportionation and the gold–palladium nanoparticles catalyse the oxidative dehydrogenation reaction exclusivel...

  1. Silver-catalysed azide-alkyne cycloaddition (AgAAC): assessing the mechanism by density functional theory calculations

    Science.gov (United States)

    Banerji, Biswadip; Chandrasekhar, K.; Killi, Sunil Kumar; Pramanik, Sumit Kumar; Uttam, Pal; Sen, Sudeshna; Maiti, Nakul Chandra

    2016-09-01

    `Click reactions' are the copper catalysed dipolar cycloaddition reaction of azides and alkynes to incorporate nitrogens into a cyclic hydrocarbon scaffold forming a triazole ring. Owing to its efficiency and versatility, this reaction and the products, triazole-containing heterocycles, have immense importance in medicinal chemistry. Copper is the only known catalyst to carry out this reaction, the mechanism of which remains unclear. We report here that the `click reactions' can also be catalysed by silver halides in non-aqueous medium. It constitutes an alternative to the well-known CuAAC click reaction. The yield of the reaction varies on the type of counter ion present in the silver salt. This reaction exhibits significant features, such as high regioselectivity, mild reaction conditions, easy availability of substrates and reasonably good yields. In this communication, the findings of a new catalyst along with the effect of solvent and counter ions will help to decipher the still obscure mechanism of this important reaction.

  2. Vanillin formation from ferulic acid in Vanilla planifolia is catalysed by a single enzyme

    OpenAIRE

    Gallage, Nethaji Janeshawari; Hansen, Esben Halkjær; Kannangara, Rubini Maya; Olsen, Carl Erik; Motawie, Mohammed Saddik; Jørgensen, Kirsten; Holme, Inger; Hebelstrup, Kim; Grisoni, Michel; Møller, Birger Lindberg

    2014-01-01

    Vanillin is a popular and valuable flavour compound. It is the key constituent of the natural vanilla flavour obtained from cured vanilla pods. Here we show that a single hydratase/lyase type enzyme designated vanillin synthase (VpVAN) catalyses direct conversion of ferulic acid and its glucoside into vanillin and its glucoside, respectively. The enzyme shows high sequence similarity to cysteine proteinases and is specific to the substitution pattern at the aromatic ring and does not metaboli...

  3. Synthesis of 11C labelled methyl esters: transesterification of enol esters versus BF3 catalysed esterification-a comparative study

    International Nuclear Information System (INIS)

    C-11 labelled methyl esters have been synthesized via the transesterification of enol esters in the presence of C-11 methanol and 1,3 dichlorodibutylstannoxane as catalyst. This method leaves functional groups intact and allows access to a wider variety of C-11 labelled methyl esters compared to the BF3 catalysed ester formation, which uses carboxylic acids and C-11 methanol as starting materials

  4. Rhodium-catalysed asymmetric allylic arylation of racemic halides with arylboronic acids

    Science.gov (United States)

    Sidera, Mireia; Fletcher, Stephen P.

    2015-11-01

    Csp2-Csp2 cross-coupling reactions between arylboronic acid and aryl halides are widely used in both academia and industry and are strategically important in the development of new agrochemicals and pharmaceuticals. Csp2-Csp3 cross-coupling reactions have been developed, but enantioselective variations are rare and simply retaining the stereochemistry is a problem. Here we report a highly enantioselective Csp2-Csp3 bond-forming method that couples arylboronic acids to racemic allyl chlorides. Both enantiomers of a cyclic chloride are converted into a single enantiomer of product via a dynamic kinetic asymmetric transformation. This Rh-catalysed method uses readily available and inexpensive building blocks and is mild and broadly applicable. For electron-deficient, electron-rich or ortho-substituted boronic acids better results are obtained with racemic allyl bromides. Oxygen substitution in the allyl halide is tolerated and the products can be functionalized to provide diverse building blocks. The approach fills a significant gap in the methods for catalytic asymmetric synthesis.

  5. Vanillin formation from ferulic acid in Vanilla planifolia is catalysed by a single enzyme.

    Science.gov (United States)

    Gallage, Nethaji J; Hansen, Esben H; Kannangara, Rubini; Olsen, Carl Erik; Motawia, Mohammed Saddik; Jørgensen, Kirsten; Holme, Inger; Hebelstrup, Kim; Grisoni, Michel; Møller, Birger Lindberg

    2014-01-01

    Vanillin is a popular and valuable flavour compound. It is the key constituent of the natural vanilla flavour obtained from cured vanilla pods. Here we show that a single hydratase/lyase type enzyme designated vanillin synthase (VpVAN) catalyses direct conversion of ferulic acid and its glucoside into vanillin and its glucoside, respectively. The enzyme shows high sequence similarity to cysteine proteinases and is specific to the substitution pattern at the aromatic ring and does not metabolize caffeic acid and p-coumaric acid as demonstrated by coupled transcription/translation assays. VpVAN localizes to the inner part of the vanilla pod and high transcript levels are found in single cells located a few cell layers from the inner epidermis. Transient expression of VpVAN in tobacco and stable expression in barley in combination with the action of endogenous alcohol dehydrogenases and UDP-glucosyltransferases result in vanillyl alcohol glucoside formation from endogenous ferulic acid. A gene encoding an enzyme showing 71% sequence identity to VpVAN was identified in another vanillin-producing plant species Glechoma hederacea and was also shown to be a vanillin synthase as demonstrated by transient expression in tobacco. PMID:24941968

  6. Vanillin formation from ferulic acid in Vanilla planifolia is catalysed by a single enzyme.

    Science.gov (United States)

    Gallage, Nethaji J; Hansen, Esben H; Kannangara, Rubini; Olsen, Carl Erik; Motawia, Mohammed Saddik; Jørgensen, Kirsten; Holme, Inger; Hebelstrup, Kim; Grisoni, Michel; Møller, Birger Lindberg

    2014-06-19

    Vanillin is a popular and valuable flavour compound. It is the key constituent of the natural vanilla flavour obtained from cured vanilla pods. Here we show that a single hydratase/lyase type enzyme designated vanillin synthase (VpVAN) catalyses direct conversion of ferulic acid and its glucoside into vanillin and its glucoside, respectively. The enzyme shows high sequence similarity to cysteine proteinases and is specific to the substitution pattern at the aromatic ring and does not metabolize caffeic acid and p-coumaric acid as demonstrated by coupled transcription/translation assays. VpVAN localizes to the inner part of the vanilla pod and high transcript levels are found in single cells located a few cell layers from the inner epidermis. Transient expression of VpVAN in tobacco and stable expression in barley in combination with the action of endogenous alcohol dehydrogenases and UDP-glucosyltransferases result in vanillyl alcohol glucoside formation from endogenous ferulic acid. A gene encoding an enzyme showing 71% sequence identity to VpVAN was identified in another vanillin-producing plant species Glechoma hederacea and was also shown to be a vanillin synthase as demonstrated by transient expression in tobacco.

  7. Characterisation of hydrocarbonaceous overlayers important in metal-catalysed selective hydrogenation reactions

    Energy Technology Data Exchange (ETDEWEB)

    Lennon, David; Warringham, Robbie [School of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Guidi, Tatiana [ISIS Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom); Parker, Stewart F., E-mail: stewart.parker@stfc.ac.uk [ISIS Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom)

    2013-12-12

    Highlights: • Inelastic neutron scattering spectroscopy of a commercial dehydrogenation catalyst. • The overlayer present on the catalyst is predominantly aliphatic. • A population of strongly hydrogen bonded hydroxyls is also present. - Abstract: The hydrogenation of alkynes to alkenes over supported metal catalysts is an important industrial process and it has been shown that hydrocarbonaceous overlayers are important in controlling selectivity profiles of metal-catalysed hydrogenation reactions. As a model system, we have selected propyne hydrogenation over a commercial Pd(5%)/Al{sub 2}O{sub 3} catalyst. Inelastic neutron scattering studies show that the C–H stretching mode ranges from 2850 to 3063 cm{sup −1}, indicating the mostly aliphatic nature of the overlayer and this is supported by the quantification of the carbon and hydrogen on the surface. There is also a population of strongly hydrogen-bonded hydroxyls, their presence would indicate that the overlayer probably contains some oxygen functionality. There is little evidence for any olefinic or aromatic species. This is distinctly different from the hydrogen-poor overlayers that are deposited on Ni/Al{sub 2}O{sub 3} catalysts during methane reforming.

  8. Synthesis of deuterium-labelled halogen derivatives of L-tryptophan catalysed by tryptophanase.

    Science.gov (United States)

    Winnicka, Elżbieta; Szymańska, Jolanta; Kańska, Marianna

    2016-06-01

    The isotopomers of halogen derivatives of l-tryptophan (l-Trp) (4'-F-, 7'-F-, 5'-Cl- and 7'-Br-l-Trp), specifically labelled with deuterium in α-position of the side chain, were obtained by enzymatic coupling of the corresponding halogenated derivatives of indole with S-methyl-l-cysteine in (2)H2O, catalysed by enzyme tryptophanase (EC 4.1.99.1). The positional deuterium enrichment of the resulting tryptophan derivatives was controlled using (1)H NMR. In accordance with the mechanism of the lyase reaction, a 100% deuterium labelling was observed in the α-position; the chemical yields were between 23 and 51%. Furthermore, β-F-l-alanine, synthesized from β-F-pyruvic acid by the l-alanine dehydrogenase reaction, has been tested as a coupling agent to obtain the halogenated deuterium-labelled derivatives of l-Trp. The chemical yield (∼30%) corresponded to that as observed with S-methyl-l-cysteine but the deuterium label was only 63%, probably due to the use of a not completely deuterated incubation medium.

  9. Sequence-defined bioactive macrocycles via an acid-catalysed cascade reaction

    Science.gov (United States)

    Porel, Mintu; Thornlow, Dana N.; Phan, Ngoc N.; Alabi, Christopher A.

    2016-06-01

    Synthetic macrocycles derived from sequence-defined oligomers are a unique structural class whose ring size, sequence and structure can be tuned via precise organization of the primary sequence. Similar to peptides and other peptidomimetics, these well-defined synthetic macromolecules become pharmacologically relevant when bioactive side chains are incorporated into their primary sequence. In this article, we report the synthesis of oligothioetheramide (oligoTEA) macrocycles via a one-pot acid-catalysed cascade reaction. The versatility of the cyclization chemistry and modularity of the assembly process was demonstrated via the synthesis of >20 diverse oligoTEA macrocycles. Structural characterization via NMR spectroscopy revealed the presence of conformational isomers, which enabled the determination of local chain dynamics within the macromolecular structure. Finally, we demonstrate the biological activity of oligoTEA macrocycles designed to mimic facially amphiphilic antimicrobial peptides. The preliminary results indicate that macrocyclic oligoTEAs with just two-to-three cationic charge centres can elicit potent antibacterial activity against Gram-positive and Gram-negative bacteria.

  10. Glycolysis of carbon fiber-epoxy unidirectional mat catalysed by sodium hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Zaini, Mariana Binti Mohd [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Badri, Khairiah Haji [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia and Polymer Research Center, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43 (Malaysia)

    2014-09-03

    This study was conducted to recycle carbon fibre-epoxy (CFRP) composite in woven sheet/ mat form. The CFRP was recycled through glycolysis with polyethlyene glycol (PEG 200) as the solvent. The CFRP was loaded into the solvent at a ratio of 4:1 (w/w). PEG200 was diluted with water to a ratio of 80:20 (v/v). This reaction was catalysed by sodium hydroxide (NaOH) solution with varying concentrations at 1.5, 1.7 and 1.9% (w/v). The glycolysis was conducted at 180-190 °C. The recovered CF (rCF) was analysed using Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDX) while the degraded solution was analysed using FTIR and the epoxy content was determined. The FTIR spectrum of the rCF exhibited the disappearance of the COC peak belonged to epoxy and supported by the SEM micrographs that showed clear rCF. On the other hand, the analysed filtrate detected the disappearance of oxygen peak element in the EDX spectrum for all rCF samples. This gave an indication that the epoxy resin has been removed from the surface of the carbon fiber.

  11. Glycolysis of carbon fiber-epoxy unidirectional mat catalysed by sodium hydroxide

    Science.gov (United States)

    Zaini, Mariana Binti Mohd; Badri, Khairiah Haji

    2014-09-01

    This study was conducted to recycle carbon fibre-epoxy (CFRP) composite in woven sheet/ mat form. The CFRP was recycled through glycolysis with polyethlyene glycol (PEG 200) as the solvent. The CFRP was loaded into the solvent at a ratio of 4:1 (w/w). PEG200 was diluted with water to a ratio of 80:20 (v/v). This reaction was catalysed by sodium hydroxide (NaOH) solution with varying concentrations at 1.5, 1.7 and 1.9% (w/v). The glycolysis was conducted at 180-190 °C. The recovered CF (rCF) was analysed using Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDX) while the degraded solution was analysed using FTIR and the epoxy content was determined. The FTIR spectrum of the rCF exhibited the disappearance of the COC peak belonged to epoxy and supported by the SEM micrographs that showed clear rCF. On the other hand, the analysed filtrate detected the disappearance of oxygen peak element in the EDX spectrum for all rCF samples. This gave an indication that the epoxy resin has been removed from the surface of the carbon fiber.

  12. Estimation of Kinetic Parameters for Enzyme Catalysed Batch Bioreactor for the Production of Ethanol from Corn

    Directory of Open Access Journals (Sweden)

    Z. R. Yelebe

    2014-03-01

    Full Text Available This paper addresses the challenge of estimating various kinetic parameters for the design of an optimized enzyme catalysed batch bioreactor of high efficiency and yield. Mathematical models were developed to describe the batch reaction time in relation to the substrate, enzyme and product concentration. The results obtained from the plots generated were: 35.50gmol/l.hr for the velocity of reaction of the enzymes (Vmax, 0.10049hr-1 for the maximum specific growth rate (µmax 826.45gmol/l for the Michaelis-Menten constant (Km, 0.005402577 for maintenance coefficient (Ms, 10.104kgCx/kgCs for yield of cell weight per unit weight of substrate (Ycx/CS, 0.05436kgCp/kgCs for yield of product weight per unit weight of substrate utilized (Ycp/CS and 0.01416 for endogenous decay coefficient (Kd for the design of the batch biochemical reactor. Hence, they are useful parameters for predicting the most appropriate batch reaction conditions and the efficiency of the bioreactor. The mathematical model predictions showed that it can be considered as a good complimentary tool to real system since the simulation results of the mathematical model agrees with experimental data reported in literature.

  13. Palladium-catalysed transannular C-H functionalization of alicyclic amines

    Science.gov (United States)

    Topczewski, Joseph J.; Cabrera, Pablo J.; Saper, Noam I.; Sanford, Melanie S.

    2016-03-01

    Discovering pharmaceutical candidates is a resource-intensive enterprise that frequently requires the parallel synthesis of hundreds or even thousands of molecules. C-H bonds are present in almost all pharmaceutical agents. Consequently, the development of selective, rapid and efficient methods for converting these bonds into new chemical entities has the potential to streamline pharmaceutical development. Saturated nitrogen-containing heterocycles (alicyclic amines) feature prominently in pharmaceuticals, such as treatments for depression (paroxetine, amitifadine), diabetes (gliclazide), leukaemia (alvocidib), schizophrenia (risperidone, belaperidone), malaria (mefloquine) and nicotine addiction (cytisine, varenicline). However, existing methods for the C-H functionalization of saturated nitrogen heterocycles, particularly at sites remote to nitrogen, remain extremely limited. Here we report a transannular approach to selectively manipulate the C-H bonds of alicyclic amines at sites remote to nitrogen. Our reaction uses the boat conformation of the substrates to achieve palladium-catalysed amine-directed conversion of C-H bonds to C-C bonds on various alicyclic amine scaffolds. We demonstrate this approach by synthesizing new derivatives of several bioactive molecules, including varenicline.

  14. Acid-catalysed xylose dehydration into furfural in the presence of kraft lignin.

    Science.gov (United States)

    Lamminpää, Kaisa; Ahola, Juha; Tanskanen, Juha

    2015-02-01

    In this study, the effects of kraft lignin (Indulin AT) on acid-catalysed xylose dehydration into furfural were studied in formic and sulphuric acids. The study was done using D-optimal design. Three variables in both acids were included in the design: time (20-80 min), temperature (160-180°C) and initial lignin concentration (0-20 g/l). The dependent variables were xylose conversion, furfural yield, furfural selectivity and pH change. The results showed that the xylose conversion and furfural yield decreased in sulphuric acid, while in formic acid the changes were minor. Additionally, it was showed that lignin has an acid-neutralising capacity, and the added lignin increased the pH of reactant solutions in both acids. The pH rise was considerably lower in formic acid than in sulphuric acid. However, the higher pH did not explain all the changes in conversion and yield, and thus lignin evidently inhibits the formation of furfural.

  15. Meiotic recombination in Arabidopsis is catalysed by DMC1, with RAD51 playing a supporting role.

    Directory of Open Access Journals (Sweden)

    Olivier Da Ines

    Full Text Available Recombination establishes the chiasmata that physically link pairs of homologous chromosomes in meiosis, ensuring their balanced segregation at the first meiotic division and generating genetic variation. The visible manifestation of genetic crossing-overs, chiasmata are the result of an intricate and tightly regulated process involving induction of DNA double-strand breaks and their repair through invasion of a homologous template DNA duplex, catalysed by RAD51 and DMC1 in most eukaryotes. We describe here a RAD51-GFP fusion protein that retains the ability to assemble at DNA breaks but has lost its DNA break repair capacity. This protein fully complements the meiotic chromosomal fragmentation and sterility of Arabidopsis rad51, but not rad51 dmc1 mutants. Even though DMC1 is the only active meiotic strand transfer protein in the absence of RAD51 catalytic activity, no effect on genetic map distance was observed in complemented rad51 plants. The presence of inactive RAD51 nucleofilaments is thus able to fully support meiotic DSB repair and normal levels of crossing-over by DMC1. Our data demonstrate that RAD51 plays a supporting role for DMC1 in meiotic recombination in the flowering plant, Arabidopsis.

  16. Enzymatic synthesis of enantiopure alpha- and beta-amino acids by phenylalanine aminomutase-catalysed amination of cinnamic acid derivatives.

    Science.gov (United States)

    Wu, Bian; Szymanski, Wiktor; Wietzes, Piet; de Wildeman, Stefaan; Poelarends, Gerrit J; Feringa, Ben L; Janssen, Dick B

    2009-01-26

    The phenylalanine aminomutase (PAM) from Taxus chinensis catalyses the conversion of alpha-phenylalanine to beta-phenylalanine, an important step in the biosynthesis of the N-benzoyl phenylisoserinoyl side-chain of the anticancer drug taxol. Mechanistic studies on PAM have suggested that (E)-cinnamic acid is an intermediate in the mutase reaction and that it can be released from the enzyme's active site. Here we describe a novel synthetic strategy that is based on the finding that ring-substituted (E)-cinnamic acids can serve as a substrate in PAM-catalysed ammonia addition reactions for the biocatalytic production of several important beta-amino acids. The enzyme has a broad substrate range and a high enantioselectivity with cinnamic acid derivatives; this allows the synthesis of several non-natural aromatic alpha- and beta-amino acids in excellent enantiomeric excess (ee >99 %). The internal 5-methylene-3,5-dihydroimidazol-4-one (MIO) cofactor is essential for the PAM-catalysed amination reactions. The regioselectivity of amination reactions was influenced by the nature of the ring substituent.

  17. Fluorescent labelling of in situ hybridisation probes through the copper-catalysed azide-alkyne cycloaddition reaction.

    Science.gov (United States)

    Hesse, Susann; Manetto, Antonio; Cassinelli, Valentina; Fuchs, Jörg; Ma, Lu; Raddaoui, Nada; Houben, Andreas

    2016-09-01

    In situ hybridisation is a powerful tool to investigate the genome and chromosome architecture. Nick translation (NT) is widely used to label DNA probes for fluorescence in situ hybridisation (FISH). However, NT is limited to the use of long double-stranded DNA and does not allow the labelling of single-stranded and short DNA, e.g. oligonucleotides. An alternative technique is the copper(I)-catalysed azide-alkyne cycloaddition (CuAAC), at which azide and alkyne functional groups react in a multistep process catalysed by copper(I) ions to give 1,4-distributed 1,2,3-triazoles at a high yield (also called 'click reaction'). We successfully applied this technique to label short single-stranded DNA probes as well as long PCR-derived double-stranded probes and tested them by FISH on plant chromosomes and nuclei. The hybridisation efficiency of differently labelled probes was compared to those obtained by conventional labelling techniques. We show that copper(I)-catalysed azide-alkyne cycloaddition-labelled probes are reliable tools to detect different types of repetitive sequences on chromosomes opening new promising routes for the detection of single copy gene. Moreover, a combination of FISH using such probes with other techniques, e.g. immunohistochemistry (IHC) and cell proliferation assays using 5-ethynyl-deoxyuridine, is herein shown to be easily feasible. PMID:27095480

  18. Calculated ionisation potentials to determine the oxidation of vanillin precursors by lignin peroxidase.

    NARCIS (Netherlands)

    ten Have, R.; Rietjens, I.M.C.M.; Hartmans, S.; Swarts, H.J.; Field, J.A.

    1998-01-01

    In view of the biocatalytic production of vanillin, this research focused on the lignin peroxidase (LiP) catalysed oxidation of naturally occurring phenolic derivatives: O-methyl ethers, O-acetyl esters, and O-glucosyl ethers. The ionisation potential (IP) of a series of model compounds was calculat

  19. Physics of Partially Ionized Plasmas

    Science.gov (United States)

    Krishan, Vinod

    2016-05-01

    Figures; Preface; 1. Partially ionized plasmas here and everywhere; 2. Multifluid description of partially ionized plasmas; 3. Equilibrium of partially ionized plasmas; 4. Waves in partially ionized plasmas; 5. Advanced topics in partially ionized plasmas; 6. Research problems in partially ionized plasmas; Supplementary matter; Index.

  20. Influence of Oxidation Pretreatment at Low Oxygen Partial Pressure on Corrosion Resistance of Nickel Base Alloy 028%低氧分压预处理对镍基合金028耐蚀性的影响

    Institute of Scientific and Technical Information of China (English)

    陈立强; 韩昱琼; 郑树启; 陈长风

    2013-01-01

    对镍基合金Alloy028在900 C进行低氧分压预处理10 h,金相观察和硬度测试结果表明,预处理后析出物减少,组织得到细化,硬度明显提高.SEM、EDS及XRD分析比较试样表面微观形貌与结构特征表明,预处理后钝化膜形成元素Cr在表面发生富集,且部分形成由Cr2O3和NiCr2O4组成的氧化膜.极化曲线测试表明,预处理后合金的自腐蚀电位从-0.37 V正移至-0.25 V(SCE),腐蚀电流密度比空白试样显著降低.电化学阻抗测试表明,预处理试样的电荷转移电阻比空白试样提高一个数量级,膜电阻提高2倍多.%The pretreatment of nickel base alloy 028 at low oxygen partial pressure was carried out at 900 C for lOh. After the pretreatment, the microstructure of the nickel alloy 028 sample was refined, precipitation along with its boundaries decreased and its hardness increased. The Cr2O3 and NiC2O4 oxide films with continuously compact structural feature were formed primarily on the sample surface. They were examined by SEM, EDS and XRD. The polarization curve of the sample after the pretreatment indicated that its corrosion potential moved from -0. 25V to 0. 37 V(SCE), and corrosion current density obviously reduced compared with those of the control sample. The measurements of EIS showed that the charge transfer resistance after pretreatment rose by an order of magnitude and the film resistance reached 2 times or more compared with those of the control sample.

  1. Beginning partial differential equations

    CERN Document Server

    O'Neil, Peter V

    2011-01-01

    A rigorous, yet accessible, introduction to partial differential equations-updated in a valuable new edition Beginning Partial Differential Equations, Second Edition provides a comprehensive introduction to partial differential equations (PDEs) with a special focus on the significance of characteristics, solutions by Fourier series, integrals and transforms, properties and physical interpretations of solutions, and a transition to the modern function space approach to PDEs. With its breadth of coverage, this new edition continues to present a broad introduction to the field, while also addres

  2. Hyperbolic partial differential equations

    CERN Document Server

    Witten, Matthew

    1986-01-01

    Hyperbolic Partial Differential Equations III is a refereed journal issue that explores the applications, theory, and/or applied methods related to hyperbolic partial differential equations, or problems arising out of hyperbolic partial differential equations, in any area of research. This journal issue is interested in all types of articles in terms of review, mini-monograph, standard study, or short communication. Some studies presented in this journal include discretization of ideal fluid dynamics in the Eulerian representation; a Riemann problem in gas dynamics with bifurcation; periodic M

  3. Alkaline-Earth-Catalysed Cross-Dehydrocoupling of Amines and Hydrosilanes: Reactivity Trends, Scope and Mechanism.

    Science.gov (United States)

    Bellini, Clément; Dorcet, Vincent; Carpentier, Jean-François; Tobisch, Sven; Sarazin, Yann

    2016-03-18

    Alkaline-earth (Ae=Ca, Sr, Ba) complexes are shown to catalyse the chemoselective cross-dehydrocoupling (CDC) of amines and hydrosilanes. Key trends were delineated in the benchmark couplings of Ph3 SiH with pyrrolidine or tBuNH2 . Ae{E(SiMe3)2}2 ⋅(THF)x (E=N, CH; x=2-3) are more efficient than {N^N}Ae{E(SiMe3)2}⋅(THF)n (E=N, CH; n=1-2) complexes (where {N^N}(-) ={ArN(o-C6H4)C(H)=NAr}(-) with Ar=2,6-iPr2 -C6H3) bearing an iminoanilide ligand, and alkyl precatalysts are better than amido analogues. Turnover frequencies (TOFs) increase in the order Ca30 products) includes diamines and di(hydrosilane)s. Kinetic analysis of the Ba-promoted CDC of pyrrolidine and Ph3SiH shows that 1) the kinetic law is rate=k[Ba](1) [amine](0) [hydrosilane](1), 2) electron-withdrawing p-substituents on the arylhydrosilane improve the reaction rate and 3) a maximal kinetic isotopic effect (kSiH/kSiD =4.7) is seen for Ph3SiX (X=H, D). DFT calculations identified the prevailing mechanism; instead of an inaccessible σ-bond-breaking metathesis pathway, the CDC appears to follow a stepwise reaction path with N-Si bond-forming nucleophilic attack of the catalytically competent Ba pyrrolide onto the incoming silane, followed by rate limiting hydrogen-atom transfer to barium. The participation of a Ba silyl species is prevented energetically. The reactivity trend Cametal centre and decreasing Ae-Namide bond strength upon descending Group 2. PMID:26864122

  4. Catalyse homogène supportée Supported Homogeneous Catalysis

    Directory of Open Access Journals (Sweden)

    Commereuc D.

    2006-11-01

    Full Text Available Les catalyseurs complexes de coordination en phase homogène offrent des performances d'activité et de sélectivité en général meilleures que celles des catalyseurs hétérogènes obtenus par les méthodes plus classiques de dépôt par voie thermique. Ils posent cependant, en raison de leur valeur plus élevée, des problèmes de récupération ou de recyclage. Le coût de la voie homogène entraîne alors bien souvent le choix de la méthode hétérogène classique, au détriment de performances plus séduisantes. On envisage ici les solutions offertes par la catalyse homogène supportée, ainsi que les difficultés rencontrées lors de la synthèse et de l'utilisation de ce type nouveau de catalyseur. Complex homogeneous-phase coordination catalysts generally have better activity and selectivity performances than those of heterogeneous catalysts produced by more conventional methods of thermal depositing. However, because of their higher value they raise problems of recovery or recycling. The cost of homogeneous catalysis thus often leads to the choice of the conventional heterogeneous method, to the detriment of more attractive performances. This article takes up the solutions offered by supported homogeneous catalysis as well as the difficulties encountered during the synthesis and use of this new type of catalyst.

  5. Defective Cytochrome P450-Catalysed Drug Metabolism in Niemann-Pick Type C Disease.

    Science.gov (United States)

    Nicoli, Elena-Raluca; Al Eisa, Nada; Cluzeau, Celine V M; Wassif, Christopher A; Gray, James; Burkert, Kathryn R; Smith, David A; Morris, Lauren; Cologna, Stephanie M; Peer, Cody J; Sissung, Tristan M; Uscatu, Constantin-Daniel; Figg, William D; Pavan, William J; Vite, Charles H; Porter, Forbes D; Platt, Frances M

    2016-01-01

    Niemann-Pick type C (NPC) disease is a neurodegenerative lysosomal storage disease caused by mutations in either the NPC1 or NPC2 gene. NPC is characterised by storage of multiple lipids in the late endosomal/lysosomal compartment, resulting in cellular and organ system dysfunction. The underlying molecular mechanisms that lead to the range of clinical presentations in NPC are not fully understood. While evaluating potential small molecule therapies in Npc1-/- mice, we observed a consistent pattern of toxicity associated with drugs metabolised by the cytochrome P450 system, suggesting a potential drug metabolism defect in NPC1 disease. Investigation of the P450 system in the context of NPC1 dysfunction revealed significant changes in the gene expression of many P450 associated genes across the full lifespan of Npc1-/- mice, decreased activity of cytochrome P450 reductase, and a global decrease of multiple cytochrome P450 catalysed dealkylation reactions. In vivo drug metabolism studies using a prototypic P450 metabolised drug, midazolam, confirmed dysfunction in drug clearance in the Npc1-/- mouse. Expression of the Phase II enzyme uridinediphosphate-glucuronosyltransferase (UGT) was also significantly reduced in Npc1-/- mice. Interestingly, reduced activity within the P450 system was also observed in heterozygous Npc1+/- mice. The reduced activity of P450 enzymes may be the result of bile acid deficiency/imbalance in Npc1-/- mice, as bile acid treatment significantly rescued P450 enzyme activity in Npc1-/- mice and has the potential to be an adjunctive therapy for NPC disease patients. The dysfunction in the cytochrome P450 system were recapitulated in the NPC1 feline model. Additionally, we present the first evidence that there are alterations in the P450 system in NPC1 patients. PMID:27019000

  6. Defective Cytochrome P450-Catalysed Drug Metabolism in Niemann-Pick Type C Disease.

    Directory of Open Access Journals (Sweden)

    Elena-Raluca Nicoli

    Full Text Available Niemann-Pick type C (NPC disease is a neurodegenerative lysosomal storage disease caused by mutations in either the NPC1 or NPC2 gene. NPC is characterised by storage of multiple lipids in the late endosomal/lysosomal compartment, resulting in cellular and organ system dysfunction. The underlying molecular mechanisms that lead to the range of clinical presentations in NPC are not fully understood. While evaluating potential small molecule therapies in Npc1-/- mice, we observed a consistent pattern of toxicity associated with drugs metabolised by the cytochrome P450 system, suggesting a potential drug metabolism defect in NPC1 disease. Investigation of the P450 system in the context of NPC1 dysfunction revealed significant changes in the gene expression of many P450 associated genes across the full lifespan of Npc1-/- mice, decreased activity of cytochrome P450 reductase, and a global decrease of multiple cytochrome P450 catalysed dealkylation reactions. In vivo drug metabolism studies using a prototypic P450 metabolised drug, midazolam, confirmed dysfunction in drug clearance in the Npc1-/- mouse. Expression of the Phase II enzyme uridinediphosphate-glucuronosyltransferase (UGT was also significantly reduced in Npc1-/- mice. Interestingly, reduced activity within the P450 system was also observed in heterozygous Npc1+/- mice. The reduced activity of P450 enzymes may be the result of bile acid deficiency/imbalance in Npc1-/- mice, as bile acid treatment significantly rescued P450 enzyme activity in Npc1-/- mice and has the potential to be an adjunctive therapy for NPC disease patients. The dysfunction in the cytochrome P450 system were recapitulated in the NPC1 feline model. Additionally, we present the first evidence that there are alterations in the P450 system in NPC1 patients.

  7. Defective Cytochrome P450-Catalysed Drug Metabolism in Niemann-Pick Type C Disease

    Science.gov (United States)

    Wassif, Christopher A.; Gray, James; Burkert, Kathryn R.; Smith, David A.; Morris, Lauren; Cologna, Stephanie M.; Peer, Cody J.; Sissung, Tristan M.; Uscatu, Constantin-Daniel; Figg, William D.; Pavan, William J.; Vite, Charles H.; Porter, Forbes D.; Platt, Frances M.

    2016-01-01

    Niemann-Pick type C (NPC) disease is a neurodegenerative lysosomal storage disease caused by mutations in either the NPC1 or NPC2 gene. NPC is characterised by storage of multiple lipids in the late endosomal/lysosomal compartment, resulting in cellular and organ system dysfunction. The underlying molecular mechanisms that lead to the range of clinical presentations in NPC are not fully understood. While evaluating potential small molecule therapies in Npc1-/- mice, we observed a consistent pattern of toxicity associated with drugs metabolised by the cytochrome P450 system, suggesting a potential drug metabolism defect in NPC1 disease. Investigation of the P450 system in the context of NPC1 dysfunction revealed significant changes in the gene expression of many P450 associated genes across the full lifespan of Npc1-/- mice, decreased activity of cytochrome P450 reductase, and a global decrease of multiple cytochrome P450 catalysed dealkylation reactions. In vivo drug metabolism studies using a prototypic P450 metabolised drug, midazolam, confirmed dysfunction in drug clearance in the Npc1-/- mouse. Expression of the Phase II enzyme uridinediphosphate-glucuronosyltransferase (UGT) was also significantly reduced in Npc1-/- mice. Interestingly, reduced activity within the P450 system was also observed in heterozygous Npc1+/- mice. The reduced activity of P450 enzymes may be the result of bile acid deficiency/imbalance in Npc1-/- mice, as bile acid treatment significantly rescued P450 enzyme activity in Npc1-/- mice and has the potential to be an adjunctive therapy for NPC disease patients. The dysfunction in the cytochrome P450 system were recapitulated in the NPC1 feline model. Additionally, we present the first evidence that there are alterations in the P450 system in NPC1 patients. PMID:27019000

  8. Alkaline-Earth-Catalysed Cross-Dehydrocoupling of Amines and Hydrosilanes: Reactivity Trends, Scope and Mechanism.

    Science.gov (United States)

    Bellini, Clément; Dorcet, Vincent; Carpentier, Jean-François; Tobisch, Sven; Sarazin, Yann

    2016-03-18

    Alkaline-earth (Ae=Ca, Sr, Ba) complexes are shown to catalyse the chemoselective cross-dehydrocoupling (CDC) of amines and hydrosilanes. Key trends were delineated in the benchmark couplings of Ph3 SiH with pyrrolidine or tBuNH2 . Ae{E(SiMe3)2}2 ⋅(THF)x (E=N, CH; x=2-3) are more efficient than {N^N}Ae{E(SiMe3)2}⋅(THF)n (E=N, CH; n=1-2) complexes (where {N^N}(-) ={ArN(o-C6H4)C(H)=NAr}(-) with Ar=2,6-iPr2 -C6H3) bearing an iminoanilide ligand, and alkyl precatalysts are better than amido analogues. Turnover frequencies (TOFs) increase in the order Ca30 products) includes diamines and di(hydrosilane)s. Kinetic analysis of the Ba-promoted CDC of pyrrolidine and Ph3SiH shows that 1) the kinetic law is rate=k[Ba](1) [amine](0) [hydrosilane](1), 2) electron-withdrawing p-substituents on the arylhydrosilane improve the reaction rate and 3) a maximal kinetic isotopic effect (kSiH/kSiD =4.7) is seen for Ph3SiX (X=H, D). DFT calculations identified the prevailing mechanism; instead of an inaccessible σ-bond-breaking metathesis pathway, the CDC appears to follow a stepwise reaction path with N-Si bond-forming nucleophilic attack of the catalytically competent Ba pyrrolide onto the incoming silane, followed by rate limiting hydrogen-atom transfer to barium. The participation of a Ba silyl species is prevented energetically. The reactivity trend Cametal centre and decreasing Ae-Namide bond strength upon descending Group 2.

  9. C-13 isotopic studies of the surface catalysed reactions of methane

    Energy Technology Data Exchange (ETDEWEB)

    Long, M.A.; He, S.J.X.; Adebajo, M. [University of New South Wales, Sydney, NSW (Australia). School of Chemistry

    1997-10-01

    The ability of methane to methylate aromatic compounds, which are considered to be models for coal, is being studied. Related to this reaction, but at higher temperatures, is the direct formation of benzene from methane in the presence of these catalysts. Controversy exists in the literature on the former reaction, and {sup 13}C isotope studies are being used to resolve the question. The interest in this reaction arises because the utilisation of methane, in the form of natural gas, in place of hydrogen for direct coal liquefaction would have major economic advantage. For this reason Isotope studies in this area have contributed significantly to an understanding of the methylation reactions. The paper describes experiments utilising methane{sup 13}C, which show that methylation of aromatics such as naphthalene by the methane{sup 13}C is catalysed by microporous, Cu-exchanged SAPO-5, at elevated pressures (6.8 MPa) and temperatures around 400 degree C. The mass spectrometric analysis and n.m.r. study of the isotopic composition of the products of the methylation reaction demonstrate unequivocally that methane provides the additional carbon atom for the methylated products. Thermodynamic calculations predict that the reaction is favourable at high methane pressures under these experimental conditions. The mechanism as suggested by the isotope study is discussed. The catalysts which show activity for the activation of methane for direct methylation of organic compounds, such as naphthalene, toluene, phenol and pyrene, are substituted aluminophosphate molecular sieves, EIAPO-5 (where El=Pb, Cu, Ni and Si) and a number of metal substituted zeolites. Our earlier tritium studies had shown that these catalysts will activate alkanes, at least as far as isotope hydrogen exchange reactions are concerned

  10. C-13 isotopic studies of the surface catalysed reactions of methane

    International Nuclear Information System (INIS)

    The ability of methane to methylate aromatic compounds, which are considered to be models for coal, is being studied. Related to this reaction, but at higher temperatures, is the direct formation of benzene from methane in the presence of these catalysts. Controversy exists in the literature on the former reaction, and 13C isotope studies are being used to resolve the question. The interest in this reaction arises because the utilisation of methane, in the form of natural gas, in place of hydrogen for direct coal liquefaction would have major economic advantage. For this reason Isotope studies in this area have contributed significantly to an understanding of the methylation reactions. The paper describes experiments utilising methane13C, which show that methylation of aromatics such as naphthalene by the methane13C is catalysed by microporous, Cu-exchanged SAPO-5, at elevated pressures (6.8 MPa) and temperatures around 400 degree C. The mass spectrometric analysis and n.m.r. study of the isotopic composition of the products of the methylation reaction demonstrate unequivocally that methane provides the additional carbon atom for the methylated products. Thermodynamic calculations predict that the reaction is favourable at high methane pressures under these experimental conditions. The mechanism as suggested by the isotope study is discussed. The catalysts which show activity for the activation of methane for direct methylation of organic compounds, such as naphthalene, toluene, phenol and pyrene, are substituted aluminophosphate molecular sieves, EIAPO-5 (where El=Pb, Cu, Ni and Si) and a number of metal substituted zeolites. Our earlier tritium studies had shown that these catalysts will activate alkanes, at least as far as isotope hydrogen exchange reactions are concerned

  11. Kinetics of acyl transfer reactions in organic media catalysed by Candida antarctica lipase B.

    Science.gov (United States)

    Martinelle, M; Hult, K

    1995-09-01

    The acyl transfer reactions catalysed by Candida antartica lipase B in organic media followed a bi-bi ping-pong mechanism, with competitive substrate inhibition by the alcohols used as acyl acceptors. The effect of organic solvents on Vm and Km was investigated. The Vm values in acetonitrile was 40-50% of those in heptane. High Km values in acetonitrile compared to those in heptane could partly be explained by an increased solvation of the substrates in acetonitrile. Substrate solvation caused a 10-fold change in substrate specificity, defined as (Vm/Km)ethyl octanoate/(Vm/Km)octanoic acid, going from heptane to acetonitrile. Deacylation was the rate determining step for the acyl transfer in heptane with vinyl- and ethyl octanoate as acyl donors and (R)-2-octanol as acyl acceptor. With 1-octanol, a rate determining deacylation step in heptane was indicated using the same acyl donors. Using 1-octanol as acceptor in heptane, S-ethyl thiooctanoate had a 25- to 30-fold lower Vm/Km value and vinyl octanoate a 4-fold higher Vm/Km value than that for ethyl octanoate. The difference showed to be a Km effect for vinyl octanoate and mainly a Km effect for S-ethyl thiooctanoate. The Vm values of the esterification of octanoic acid with different alcohols was 10-30-times lower than those for the corresponding transesterification of ethyl octanoate. The low activity could be explained by a low pH around the enzyme caused by the acid or a withdrawing of active enzyme by nonproductive binding by the acid.

  12. Solvent-free lipase catalysed synthesis of diacylgycerols as low-calorie food ingredients

    Directory of Open Access Journals (Sweden)

    Luis eVazquez

    2016-02-01

    Full Text Available Problems derived from obesity and overweight have recently promoted the development of fat substitutes and other low-calorie foods. On the one hand, fats with short and medium chain fatty acids are a source of quick energy, easily hydrolyzable and hardly stored as fat. Furthermore, 1,3-diacylglycerols are not hydrolyzed to 2-monoacylglycerols in the gastrointestinal tract, reducing the formation of chylomicron and lowers the serum level of triacylglycerols by decreasing its re-synthesis in the enterocyte and its metabolism and absorption by the enterocyte are limited in comparison with the TAG, reducing chylomicron formation. In this work these two effects were combined to synthesize short and medium chain 1,3 diacylglycerols, leading to a product with great potential as for their low-calorie properties. Lipase catalysed transesterification reactions were performed between short and medium chain fatty acid ethyl esters and glycerol. Different variables were investigated such as the type of biocatalyst, the molar ratio FAEE:glycerol, the adsorption of glycerol on silica gel or the addition of lecithin. Best reaction conditions were evaluated considering the conversion intopercentage of 1,3-DAG produced and the reaction rate. Except Novozym 435 (Candida antarctica, other lipases required the adsorption of glycerol on silica gel to form acylglycerols. Lipases that gave the best results with adsorption were Novozym 435 and Lipozyme RM IM (Rhizomucor miehei with 52% and 60.7% of DAG at 32 h, respectively. Because of its specificity for sn-1 and sn-3 positions, lipases leading to a higher proportion of 1,3-DAG vs 1,2-DAG were Lipozyme RM IM (39.8% and 20.9%, respectively and Lipase PLG (Alcaligenes sp. (35.9% and 19.3%, respectively. By adding 1% (w/w of lecithin to the reaction with Novozym 435 and raw glycerol the reaction rate was considerably increased from 41.7% to 52.8% DAG at 24 h.

  13. Partial knee replacement - slideshow

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/presentations/100225.htm Partial knee replacement - series To use the sharing features on ... A.M. Editorial team. Related MedlinePlus Health Topics Knee Replacement A.D.A.M., Inc. is accredited ...

  14. Partial motor status epilepticus

    OpenAIRE

    Gilberto Rebello de Mattos; José C. Rollemberg Filho

    1992-01-01

    We report the case of a young female patient with photosensitive primary epilepsy who presented partial motor status epilepticus provoked by the act of shutting the eyes. Clinical, EEG and neuroimage data are presented and discussed.

  15. Beginning partial differential equations

    CERN Document Server

    O'Neil, Peter V

    2014-01-01

    A broad introduction to PDEs with an emphasis on specialized topics and applications occurring in a variety of fields Featuring a thoroughly revised presentation of topics, Beginning Partial Differential Equations, Third Edition provides a challenging, yet accessible,combination of techniques, applications, and introductory theory on the subjectof partial differential equations. The new edition offers nonstandard coverageon material including Burger's equation, the telegraph equation, damped wavemotion, and the use of characteristics to solve nonhomogeneous problems. The Third Edition is or

  16. Generalized Partial Volume

    DEFF Research Database (Denmark)

    Darkner, Sune; Sporring, Jon

    2011-01-01

    Mutual Information (MI) and normalized mutual information (NMI) are popular choices as similarity measure for multimodal image registration. Presently, one of two approaches is often used for estimating these measures: The Parzen Window (PW) and the Generalized Partial Volume (GPV). Their theoret......Mutual Information (MI) and normalized mutual information (NMI) are popular choices as similarity measure for multimodal image registration. Presently, one of two approaches is often used for estimating these measures: The Parzen Window (PW) and the Generalized Partial Volume (GPV...

  17. Peroxide-dependent amino acid oxidation and chemiluminescence catalysed by magnesium-pyridoxal phosphate-glutamate complex.

    Science.gov (United States)

    Meyer, B U; Schneider, W; Elstner, E F

    1992-08-01

    Magnesium-pyridoxal-5'-phosphate-glutamate (MPPG) has been shown to ameliorate atherosclerotic symptoms in rabbits. In vitro, MPPG in the presence of peroxides such as cholesterolhydroperoxide or cumene hydroperoxide and Mn2+ ions produces "excited states" measurable as chemiluminescence or ethylene release from 1-aminocyclopropane-1-carboxylic acid (ACC). The reactions are stimulated synergistically by unsaturated fatty acids. Pyridoxal phosphate exhibits similar properties, but can be differentiated from the activities of MPPG or the sum of the components present in MPPG. PMID:1510700

  18. Exogenous ferrous iron is required for the nitric oxide-catalysed destruction of the iron-sulphur centre in adrenodoxin.

    Science.gov (United States)

    Voevodskaya, Nina V; Serezhenkov, Vladimir A; Cooper, Chris E; Kubrina, Lioudmila N; Vanin, Anatoly F

    2002-01-01

    No effects of gaseous NO added at a pressure of 19.95 kPa on the stability of the binuclear iron-sulphur centre (ISC) of reduced iron-sulphur protein adrenodoxin (0.2 mM) have been observed using the EPR method. However, the incubation of the protein with NO in the presence of ferrous iron (1.8 mM) led to complete ISC degradation, accompanied by the formation of protein-bound dinitrosyl iron complexes (DNICs; 0.3+/-0.1 mM). Similar results were obtained when low-molecular-mass DNIC with phosphate or cysteine (1.8 mM) were added to solutions of pre-reduced adrenodoxin. The degradation of the ISC was suggested to be due to the attack of the Fe(+)(NO(+))(2) group from low-molecular-mass DNICs added or formed during the interaction between NO and ferrous ions on the thiol groups in active centres of adrenodoxin. This attack leads to a release of endogenous iron from the centres, which is capable of forming both low-molecular-mass and protein-bound DNIC, thereby ensuring further ISC degradation. PMID:12169095

  19. A four-helix bundle stores copper for methane oxidation

    OpenAIRE

    Vita, Nicholas; Platsaki, Semeli; Baslé, Arnaud; Allen, Stephen J; Paterson, Neil G.; Crombie, Andrew T.; Murrell, J Colin; Waldron, Kevin J.; Dennison, Christopher

    2015-01-01

    Methane-oxidising bacteria (methanotrophs) require large quantities of copper for the membrane-bound (particulate) methane monooxygenase (pMMO) 1,2 . Certain methanotrophs are also able to switch to using the iron-containing soluble MMO (sMMO) to catalyse methane oxidation, with this switchover regulated by copper 3,4 . MMOs are Nature’s primary biological mechanism for suppressing atmospheric levels of methane, a potent greenhouse gas. Furthermore, methanotrophs and MMOs have enormous potent...

  20. Hydrogen Production from Partial Oxidation of Methane by Dielectric Barrier Discharge Plasma Reforming%介质阻挡放电等离子体甲烷部分氧化重整制氢

    Institute of Scientific and Technical Information of China (English)

    王皓; 宋凌珺; 李兴虎; 岳丽蒙

    2015-01-01

    在自制的介质阻挡放电等离子体重整制氢装置上进行了甲烷部分氧化重整制氢的实验研究.本文研究了氧碳(O/C)摩尔比,进气流量,放电间隙,放电区间长度,填充物的直径、形状和材料,放电电压和放电频率对甲烷转化率、氢产率和产物的选择性(H2、CO和CO2)的影响.实验结果表明:放电区域的参数对甲烷转化率有较大的影响.甲烷转化率随着放电区域长度的增大而增大,当放电区域长度从5 cm增大到20 cm时,甲烷转化率从6.87%增大到22.26%,增大率为224%.同时,放电区域的填充物对产氢效果有较大的影响.当反应器填充颗粒时,甲烷转化率比无填充物时高.选择适当介电常数的填充物具有巨大的实际工程意义.另外,氢产率和氢气的选择性随着放电频率的增大而增大,当放电频率从1.5 kHz增大到7.0 kHz时,氢产率从1.10%增大到9.49%,氢气的选择性从21.18%增大到30.06%.实验结果将对碳氢燃料等离子体重整制氢的车载应用提供实验依据.%This paper presents an in-house-designed dielectric barrier discharge (DBD) plasma reformer for hydrogen production via partial oxidation reforming of methane. We examined the effects of oxygen/carbon (O/C) molar ratio, feed flow rate, discharge gap, discharge zone length, fil er diameter, fil er shape, fil er materials, discharge voltage, and discharge frequency on the hydrogen production performance i.e., CH4 conversion rate, H2 yield, and selectivity of products (H2, CO, and CO2). The experimental results showed that the parameters of the discharge zone played an important role in the CH4 conversion rate. For instance, CH4 conversion rate increased with increasing discharge zone lengths. When the discharge zone length increased from 5 to 20 cm, CH4 conversion rate increased from 6.87%to 22.26%, which corresponds to an improvement of 224%. Also, the fil ers in the discharge zone strongly

  1. Homogeneously catalysed hydrogenation of unsaturated fatty acids to unsaturated fatty alcohols

    NARCIS (Netherlands)

    Stouthamer, B.; Vlugter, J.C.

    1965-01-01

    The use of copper and cadmium oxides or soaps as catalysts for the hydrogenation of unsaturated fatty acids to unsaturated fatty alcohols has been investigated. It is shown that copper soaps homogeneously activate hydrogen. When copper and cadmium oxides are used as catalysts, they react with the ac

  2. N-Heterocyclic Carbene-Catalysed Diastereoselective Vinylogous Michael Addition Reaction of gamma-Substituted deconjugated Butenolides

    KAUST Repository

    Guo, Hao

    2015-11-16

    An efficient N-heterocyclic carbene (NHC)-catalysed vinylogous Michael addition of deconjugated butenolides was developed. In the presence of 5 mol% of the NHC catalyst, both γ-alkyl and aryl-substituted deconjugated butenolides undergo vinylogous Michael addition with various α, β-unsaturated ketones, esters, or nitriles to afford γ,γ-disubstituted butenolides containing adjacent quaternary and tertiary carbon centers in good to excellent yields with excellent diastereoselectivities. In this process, the free carbene is assumed to act as a strong Brønsted base to promote the conjugate addition.

  3. Highly Enantioselective Formation of α-Allyl-α-Arylcyclopentanones via Pd-Catalysed Decarboxylative Asymmetric Allylic Alkylation.

    Science.gov (United States)

    Akula, Ramulu; Doran, Robert; Guiry, Patrick J

    2016-07-11

    A highly enantioselective Pd-catalysed decarboxylative asymmetric allylic alkylation of cyclopentanone derived α-aryl-β-keto esters employing the (R,R)-ANDEN-phenyl Trost ligand has been developed. The product (S)-α-allyl-α-arylcyclopentanones were obtained in excellent yields and enantioselectivities (up to >99.9 % ee). This represents one of the most highly enantioselective formations of an all-carbon quaternary stereogenic center reported to date. This reaction was demonstrated on a 4.0 mmol scale without any deterioration of enantioselectivity and was exploited as the key enantioselective transformation in an asymmetric formal synthesis of the natural product (+)-tanikolide. PMID:27191198

  4. Rh-catalysed [5 + 1] cycloaddition of allenylcyclopropanes and CO: reaction development and application to the formal synthesis of (-)-galanthamine.

    Science.gov (United States)

    Liu, Cheng-Hang; Yu, Zhi-Xiang

    2016-07-01

    A Rh-catalysed [5 + 1] cycloaddition of allenylcyclopropanes and CO has been developed to synthesize functionalized 2-methylidene-3,4-cyclohexenones. The scope of this methodology has been investigated, showing that various functional groups can be tolerated. Both di- and tri-substituted allenylcyclopropanes can be applied to this cycloaddition and the [5 + 1] cycloadducts with the E configuration were obtained as the major products. In addition, the present [5 + 1] cycloaddition reaction has been utilized as a key step in the formal synthesis of the natural product (-)-galanthamine. PMID:27253492

  5. Pd-catalysed direct arylation polymerisation for synthesis of low-bandgap conjugated polymers and photovoltaic performance.

    Science.gov (United States)

    Chang, Shu-Wei; Waters, Huw; Kettle, Jeff; Kuo, Zi-Rui; Li, Chun-Han; Yu, Chin-Yang; Horie, Masaki

    2012-11-23

    Low-bandgap conjugated copolymers based on a donor-acceptor structure have been synthesised via palladium-complex catalysed direct arylation polymerisation. Initially, we report the optimisation of the synthesis of poly(cyclopentadithiophene-alt-benzothiadiazole) (PCPDTBT) formed between cyclopentadithiophene and dibromobenzothiadiazole units. The polymerisation condition has been optimised, which affords high-molecular-weight polymers of up to M(n) = 70 k using N-methylpyrrolidone as a solvent. The polymers are used to fabricate organic photovoltaic devices and the best performing PCPDTBT device exhibits a moderate improvement over devices fabricated using the related polymer via Suzuki coupling. Similar polymerisation conditions have also been applied for other monomer units.

  6. Triton-B Adsorbed on Flysh: An Efficient Support for the Base Catalysed Reactions under Microwave Irradiations

    Directory of Open Access Journals (Sweden)

    VIJENDER GOEL

    2012-12-01

    Full Text Available The application of Triton-B adsorbed on flyash (a waste material of thermal plants has been reported for the variety of base catalysed reactions such as synthesis of cinnamic acids by Deobner reaction, synthesis of 1-(2-hydroxyphenyl-5-phenylpent-4-ene-1, 3-diones by Baker-Venkataraman reaction and synthesis of 3-carboxycoumarins by knoevenagel reaction. This material also acts as a support for the reaction and avoids the use of any solvent in the reaction maintaining the norms of Green Chemistry.

  7. Low-ammonia niche of ammonia-oxidizing archaea in rotating biological contactors of a municipal wastewater treatment plant

    NARCIS (Netherlands)

    Sauder, L.A.; Peterse, F.; Schouten, S.; Neufeld, J.D.

    2012-01-01

    The first step of nitrification is catalysed by both ammonia-oxidizing bacteria (AOB) and archaea (AOA), but physicochemical controls on the relative abundance and function of these two groups are not yet fully understood, especially in freshwater environments. This study investigated ammonia-oxidiz

  8. Recent Achievements in the Radiation-Catalysed Chlorination of Chlorinated Pentane Derivatives

    International Nuclear Information System (INIS)

    The radiation-catalysed chlorination of the so-called tetrachloro-cyclopentane, the product obtained from cyclopentadiene by addition of chlorine, has already been studied earlier by the authors with success. On maintaining an adequate dosage rate, no ring cleavage occurs, and, mainly for stereochemical reasons, octachloro-cyclopentene forms as an end product - similarly to conventional chlorination carried out at high temperature (400-500oC), but at substantially lower temperature (170oC) and without any resin formation. It is known that besides other end products, octachloro-cyclopentene forms also from perchlorinated pentane, under simultaneous cyclization. In their recent experiments presented here, the authors investigated how and to what extent the yield of octachloro-cyclopentene is affected by additional chlorination of pentane, previously chlorinated under cooling (at 10 to 30oC). The experiments were carried out with a Co60 radiation source of 330 c at a dosage rate of 8 x 103 to 8 x 104r/hr, in a heated reaction mixture, mixed with a chlorine stream for periods not exceeding 30 hr. It was found that also this type of chlorination and cyclization takes place at a temperature substantially lower than the conventional 500-600oC. According to the experiments, in this case it is advisable to raise the initial temperature of 170oC of the reaction gradually to 220oC with the progress of the reaction, in order to promote the cyclization reaction. It was found, namely, that first the paraffin chain was further chlorinated and later the perchlorinated pentane derivatives cyclize partly to octachloro-cyclopentene, under formation of other chlorinated alkane and alkene derivatives. This reaction mechanism was also supported by thermodynamical calculations. The end product contains three main components; its content of octachloro-cyclopentene ranges between 25 and 35%. The data required for the evaluation of the economy of the method will be available only on the

  9. CaF2负载H3PMo12O40表面上激光促进甲烷部分氧化反应性能的研究%Studies on the Roles of Laser Stimulated Methane Partial Oxidation on the Surface of CaF2 Supported H3PMo12O40

    Institute of Scientific and Technical Information of China (English)

    高峰; 钟顺和

    2001-01-01

    Solid materials PMo12 and PMo12/CaF2 were prepared, and the surface structure, chemisorption to methane and the behavior of LSSR for the materials have been investigated by using IR, XRD, BET and laser stimulated surface reaction techniques. With different amounts of PMo12, the distribution of PMo12 can be controlled from less than one-layer to multi-layer on the surface of CaF2. There exist Lewis base sites O2- in MoO and Mo-O-Mo bonds as well as Lewis acid site -Mo6+- on the solid surfaces. Methane can be adsorbed on the surface MoO and Mo-O-Mo bonds with the molecular adsorption state, and the adsorption amount on MoO bond is greater. With 960 cm-1 laser to excite the surface MoO bond, the partial oxidation of methane occurred obviously at normal pressure and 200 ℃. Methanol is the direct product of methane oxidation, while HCHO, CH3OCH3 and hydrocarbons are the products of methanol reacted continuously on the solid surface. As CaF2 doesn't adsorb 960 cm-1 laser, PMo12/CaF2 can utilize the laser energy more efficiently than that of PMo12. According to the characterization and reaction results, a mechanism of LSSR for methane partial oxidation to methanol is given.

  10. Partially strong WW scattering

    International Nuclear Information System (INIS)

    What if only a light Higgs boson is discovered at the CERN LHC? Conventional wisdom tells us that the scattering of longitudinal weak gauge bosons would not grow strong at high energies. However, this is generally not true. In some composite models or general two-Higgs-doublet models, the presence of a light Higgs boson does not guarantee complete unitarization of the WW scattering. After partial unitarization by the light Higgs boson, the WW scattering becomes strongly interacting until it hits one or more heavier Higgs bosons or other strong dynamics. We analyze how LHC experiments can reveal this interesting possibility of partially strong WW scattering.

  11. Honesty in partial logic

    NARCIS (Netherlands)

    Hoek, W. van der; Jaspars, J.O.M.; Thijsse, E.

    1995-01-01

    We propose an epistemic logic in which knowledge is fully introspective and implies truth, although truth need not imply epistemic possibility. The logic is presented in sequential format and is interpreted in a natural class of partial models, called balloon models. We examine the notions of hones

  12. Partially ordered models

    NARCIS (Netherlands)

    Fernandez, R.; Deveaux, V.

    2010-01-01

    We provide a formal definition and study the basic properties of partially ordered chains (POC). These systems were proposed to model textures in image processing and to represent independence relations between random variables in statistics (in the later case they are known as Bayesian networks). O

  13. Partially Hidden Markov Models

    DEFF Research Database (Denmark)

    Forchhammer, Søren Otto; Rissanen, Jorma

    1996-01-01

    Partially Hidden Markov Models (PHMM) are introduced. They differ from the ordinary HMM's in that both the transition probabilities of the hidden states and the output probabilities are conditioned on past observations. As an illustration they are applied to black and white image compression where...

  14. Effects of oxygen partial pressure and annealing temperature on the residual stress of hafnium oxide thin-films on silicon using synchrotron-based grazing incidence X-ray diffraction

    Science.gov (United States)

    Biswas, Debaleen; Sinha, Anil Kumar; Chakraborty, Supratic

    2016-10-01

    Synchrotron radiation-based grazing incidence X-ray diffraction (GI-XRD) technique is employed here to estimate the residual stress of relaxation in the presence of excess Hf in hafnium oxide film during deposition.

  15. Theoretical studies on the mechanism of palladium(II)-catalysed ortho-carboxylation of acetanilide with CO

    Indian Academy of Sciences (India)

    Xing Hui Zhang; Zhi Yuan Geng; Ke Tai Wang

    2014-01-01

    The mechanism of palladium(II)-catalysed carboxylation of acetanilide with CO has been investigated using density functional theory calculation done at the B3LYP/6-31G(d, p)(SDD for Pd) level of theory. Solvent effects on these reactions have been explored by calculation that included a polarizable continuum model (PCM) for the solvent. Two plausible pathways which led to the formation of anhydride or benzoxazinone intermediate structure were proposed. Our calculated results suggested that the steps of forming the anhydride or benzoxazinone intermediate became the rate-determining one in the whole catalytic cycle. The process of forming benzoxazinone is more favoured kinetically with a barrier of 16.6 kcal/mol versus 22.9 kcal/mol for the pathway of forming anhydride structure. Subsequent hydrolysis process of these intermediates then provide the corresponding product ortho-acetaminobenzoic acid. The computational results are consistent with the experimental observations of Yu et al. for palladium(II)-catalysed synthesis of acetanilide based on carbon monoxide.

  16. The sulphoxidation of thioanisole catalysed by lactoperoxidase and Coprinus cinereus peroxidase: evidence for an oxygen-rebound mechanism.

    Science.gov (United States)

    Tuynman, A; Vink, M K; Dekker, H L; Schoemaker, H E; Wever, R

    1998-12-01

    Using both stopped-flow and conventional spectroscopy, the oxygenation of methyl phenyl sulphide by both lactoperoxidase (LPO) and Coprinus cinereus peroxidase (CiP) was monitored. Controlled continuous addition of H2O2 during turnover and monitoring the presence of native enzymes, compounds I, II and III, led to formation of the sulphoxide in high yield and enantioselectivity. Under those conditions, LPO catalysed the formation of (R) methyl phenyl sulphoxide with a yield of 85% and an enantiomeric excess (e.e.) of 80%. CiP catalysed the formation of (S) methyl phenyl sulphoxide with a yield of 84% and an e.e. of 73%. The enantioselective performance was markedly influenced by the purity of the enzymes used. Presence of compound III during turnover led to rapid inactivation of the peroxidases and, therefore, to both a lower yield of the sulphoxides and a lower enantioselectivity. Stopped-flow kinetic data show that, for both LPO and CiP, the transition of compound I to compound II depends on the concentration of the methyl phenyl sulphide, suggesting an oxygen-rebound mechanism. In line with this mechanism, a methyl phenyl sulphide radical cation was detected by EPR during turnover for LPO.

  17. Nitric oxide supersensitivity

    DEFF Research Database (Denmark)

    Olesen, J; Iversen, Helle Klingenberg; Thomsen, L L

    1993-01-01

    Nitroglycerin, which may be regarded as a prodrug for nitric oxide, induces a mild to moderate headache in healthy subjects. In order to study whether migraine patients are more sensitive to nitric oxide than non-migrainous subjects, four different doses of intravenous nitroglycerin were given...... previously shown a similar supersensitivity to histamine which in human cerebral arteries activates endothelial H1 receptors and causes endothelial production of nitric oxide. Migraine patients are thus supersensitive to exogenous nitric oxide from nitroglycerin as well as to endothelially produced nitric...... oxide. It is suggested that nitric oxide may be partially or completely responsible for migraine pain....

  18. A Decrease in NiO-MgO Phase Through Its Solid Solution Equilibrium with Tetragonal (La1−zSrz)2Ni1−yMgyO4−δ: Effect on Catalytic Partial Oxidation of Methane

    OpenAIRE

    Xiong Yin; Liang Hong; Zhengliang Gong

    2012-01-01

    Calcination of an oxide mixture consisting of 0.4 La2O3, 0.2 SrCO3, (1−x)NiO, and xMgO at 800∘C results in an equilibrium between tetragonal (La1−zSrz)2Ni1−yMgyO4−δ phase and NiO-MgO phase. Forming rock-salt NiO-MgO facilitates the NiO to join the tetragonal phase. The size of the NiO-MgO phase in the resulting composite is reduced with the increase in MgO (the x value). The composite thus obtained is used to catalyze partial oxidation of methane, and the maximum methane conversion of ca....

  19. Partially coherent ultrafast spectrography

    Science.gov (United States)

    Bourassin-Bouchet, C.; Couprie, M.-E.

    2015-01-01

    Modern ultrafast metrology relies on the postulate that the pulse to be measured is fully coherent, that is, that it can be completely described by its spectrum and spectral phase. However, synthesizing fully coherent pulses is not always possible in practice, especially in the domain of emerging ultrashort X-ray sources where temporal metrology is strongly needed. Here we demonstrate how frequency-resolved optical gating (FROG), the first and one of the most widespread techniques for pulse characterization, can be adapted to measure partially coherent pulses even down to the attosecond timescale. No modification of experimental apparatuses is required; only the processing of the measurement changes. To do so, we take our inspiration from other branches of physics where partial coherence is routinely dealt with, such as quantum optics and coherent diffractive imaging. This will have important and immediate applications, such as enabling the measurement of X-ray free-electron laser pulses despite timing jitter. PMID:25744080

  20. Partially predictable chaos

    CERN Document Server

    Wernecke, Hendrik; Gros, Claudius

    2016-01-01

    For a chaotic system pairs of initially close-by trajectories become eventually fully uncorrelated on the attracting set. This process of decorrelation is split into an initial decrease characterized by the maximal Lyapunov exponent and a subsequent diffusive process on the chaotic attractor causing the final loss of predictability. The time scales of both processes can be either of the same or of very different orders of magnitude. In the latter case the two trajectories linger within a finite but small distance (with respect to the overall size of the attractor) for exceedingly long times and therefore remain partially predictable. We introduce a 0-1 indicator for chaos capable of describing this scenario, arguing, in addition, that the chaotic closed braids found close to a period-doubling transition are generically partially predictable.

  1. Honesty in partial logic

    OpenAIRE

    Hoek, van, E.; Jaspars, J.O.M.; Thijsse, E.

    1995-01-01

    We propose an epistemic logic in which knowledge is fully introspective and implies truth, although truth need not imply epistemic possibility. The logic is presented in sequential format and is interpreted in a natural class of partial models, called balloon models. We examine the notions of honesty and circumscription in this logic: What is the state of an agent that `only knows $phi$' and which honest $phi$ enable such circumscription? Redefining {em stable sets enables us to provide suita...

  2. Fundamental partial compositeness

    OpenAIRE

    Sannino, Francesco; Strumia, Alessandro; Tesi, Andrea; Vigiani, Elena

    2016-01-01

    We construct renormalizable Standard Model extensions, valid up to the Planck scale, that give a composite Higgs from a new fundamental strong force acting on fermions and scalars. Yukawa interactions of these particles with Standard Model fermions realize the partial compositeness scenario. Successful models exist because gauge quantum numbers of Standard Model fermions admit a minimal enough 'square root'. Furthermore, right-handed SM fermions have an SU(2)$_R$-like structure, yielding a cu...

  3. Arthroscopic partial medial meniscectomy

    Directory of Open Access Journals (Sweden)

    Dašić Žarko

    2011-01-01

    Full Text Available Background/Aim. Meniscal injuries are common in professional or recreational sports as well as in daily activities. If meniscal lesions lead to physical impairment they usually require surgical treatment. Arthroscopic treatment of meniscal injuries is one of the most often performed orthopedic operative procedures. Methods. The study analyzed the results of arthroscopic partial medial meniscectomy in 213 patients in a 24-month period, from 2006, to 2008. Results. In our series of arthroscopically treated medial meniscus tears we noted 78 (36.62% vertical complete bucket handle lesions, 19 (8.92% vertical incomplete lesions, 18 (8.45% longitudinal tears, 35 (16.43% oblique tears, 18 (8.45% complex degenerative lesions, 17 (7.98% radial lesions and 28 (13.14% horisontal lesions. Mean preoperative International Knee Documentation Committee (IKDC score was 49.81%, 1 month after the arthroscopic partial medial meniscectomy the mean IKDC score was 84.08%, and 6 months after mean IKDC score was 90.36%. Six months after the procedure 197 (92.49% of patients had good or excellent subjective postoperative clinical outcomes, while 14 (6.57% patients subjectively did not notice a significant improvement after the intervention, and 2 (0.93% patients had no subjective improvement after the partial medial meniscectomy at all. Conclusion. Arthroscopic partial medial meniscetomy is minimally invasive diagnostic and therapeutic procedure and in well selected cases is a method of choice for treatment of medial meniscus injuries when repair techniques are not a viable option. It has small rate of complications, low morbidity and fast rehabilitation.

  4. Hierarchical partial order ranking

    International Nuclear Information System (INIS)

    Assessing the potential impact on environmental and human health from the production and use of chemicals or from polluted sites involves a multi-criteria evaluation scheme. A priori several parameters are to address, e.g., production tonnage, specific release scenarios, geographical and site-specific factors in addition to various substance dependent parameters. Further socio-economic factors may be taken into consideration. The number of parameters to be included may well appear to be prohibitive for developing a sensible model. The study introduces hierarchical partial order ranking (HPOR) that remedies this problem. By HPOR the original parameters are initially grouped based on their mutual connection and a set of meta-descriptors is derived representing the ranking corresponding to the single groups of descriptors, respectively. A second partial order ranking is carried out based on the meta-descriptors, the final ranking being disclosed though average ranks. An illustrative example on the prioritisation of polluted sites is given. - Hierarchical partial order ranking of polluted sites has been developed for prioritization based on a large number of parameters

  5. Rh promoted La0.75Sr0.25(Fe0.8Co0.2)1-xGaxO3-δ perovskite catalysts: Characterization and catalytic performance for methane partial oxidation to synthesis gas

    Science.gov (United States)

    Palcheva, R.; Olsbye, U.; Palcut, M.; Rauwel, P.; Tyuliev, G.; Velinov, N.; Fjellvåg, H. H.

    2015-12-01

    Synthesis gas production via selective oxidation of methane at 600 °C in a pulse reaction over La0.75Sr0.25(Fe0.8Co0.2)1-xGaxO3-δ (x = 0.1, 0.25, 0.4) perovskite-supported rhodium catalysts, was investigated. The perovskite oxides were prepared by sol-gel citrate method and characterized by X-ray Diffraction (XRD), Moessbauer Spectroscopy (MS), Temperature Programmed Reduction (TPR-H2), X-ray Photoelectron Spectroscopy (XPS) and High Resolution Transmission Electron Microscopy (HRTEM). According to XRD analysis, the synthesized samples were a single perovskite phase. The perovskite structure of Ga substituted samples remained stable after TPR-H2, as confirmed by XRD. Data of MS identified Fe3+ ions in two distinctive coordination environments, and Fe4+ ions. The Rh2O3 thin overlayer was detected by the HRTEM for the Rh impregnated perovskite oxides. During the interaction of methane with oxidized perovskite-supported Rh (0.5 wt.%) catalysts, besides CO, H2, and surface carbon, CO2 and H2O were formed. The Rh perovskite catalyst with x = 0.25 gallium exhibits the highest catalytic activity of 83% at 600 °C. The CO selectivity was affected by the reducibility of La0.75Sr0.25(Fe0.8Co0.2)1-xGaxO3-δ perovskite materials.

  6. Heme-coordinated histidine residues form non-specific functional "ferritin-heme" peroxidase system: Possible and partial mechanistic relevance to oxidative stress-mediated pathology in neurodegenerative diseases.

    Science.gov (United States)

    Esmaeili, Sajjad; Kooshk, Mohammad Reza Ashrafi; Asghari, Seyyed Mohsen; Khodarahmi, Reza

    2016-10-01

    Ferritin is a giant protein composed of 24 subunits which is able to sequester up to 4500 atoms of iron. We proposed two kinds of heme binding sites in mammalian ferritins and provided direct evidence for peroxidase activity of heme-ferritin, since there is the possibility that "ferritin-heme" systems display unexpected catalytic behavior like heme-containing enzymes. In the current study, peroxidase activity of heme-bound ferritin was studied using TMB(1), l-DOPA, serotonin, and dopamine, in the presence of H2O2, as oxidant substrate. The catalytic oxidation of TMB was consistent with first-order kinetics with respect to ferritin concentration. Perturbation of the binding affinity and catalytic behavior of heme-bound His-modified ferritin were also documented. We also discuss the importance of the peroxidase-/nitrative-mediated oxidation of vital molecules as well as ferritin-induced catalase inhibition using in vitro experimental system. Uncontrollable "heme-ferritin"-based enzyme activity as well as up-regulation of heme and ferritin may inspire that some oxidative stress-mediated cytotoxic effects in AD-affected cells could be correlated to ferritin-heme interaction and/or ferritin-induced catalase inhibition and describe its contribution as an important causative pathogenesis mechanism in some neurodegenerative disorders. PMID:27212214

  7. An alternative pathway for production of acetonitrile: ruthenium catalysed aerobic dehydrogenation of ethylamine

    DEFF Research Database (Denmark)

    Corker, Emily; Mentzel, Uffe Vie; Mielby, Jerrik Jørgen;

    2013-01-01

    The oxidative synthesis of acetonitrile from ethylamine was studied using a supported ruthenium catalyst. The reaction was conducted in both batch and flow processes and high conversions (over 85%) were achieved in both cases. Selectivity of both reactions was improved by optimisation of reaction...

  8. Urinary acetylated metabolites and N-acetyltransferase-2 genotype in human subjects treated with a para-phenylenediamine-containing oxidative hair dye

    NARCIS (Netherlands)

    Nohynek, G.J.; Skare, J.A.; Meuling, W.J.A.; Hein, D.W.; Bie, A.T.H.J. de; Toutain, H.

    2004-01-01

    In the organism of mammals, important detoxification pathways of arylamines are catalysed by N-acetyltransferase 2 (NAT2). A recent case-control epidemiology study suggested that human NAT2 slow acetylators exposed to oxidative hair dyes may be at greater risk to develop bladder cancer. We therefore

  9. New insight into the mechanism of the conjugate addition of benzenethiol to cyclic and acyclic enones and of the corresponding uranyl-salophen-catalysed version

    NARCIS (Netherlands)

    Axel Castelli, van Valeria; Dalla Cort, Antonella; Mandolini, Luigi; Reinhoudt, David N.; Schiaffino, Luca

    2003-01-01

    A thorough kinetic investigation of the triethylamine-catalysed addition of benzenethiol to 2-cyclopenten-1-one in chloroform shows that the highest energy transition state is a complex of thiol, enone, and base in a 1:1:1 ratio, but whether formation or disruption of the enolate-triethylammonium io

  10. Zn(OTf)2-catalysed indolylation and pyrrolylation of isatins: Efficient synthesis and biochemical assay of 3,3-di(heteroaryl)oxindoles

    Indian Academy of Sciences (India)

    C Praveen; S Narendiran; P Dheenkumar; P T Perumal

    2013-11-01

    An efficient and cheap synthetic approach to 3,3-di(indolyl)oxindoles and 3,3-di(pyrrolyl) oxindoles has been developed via Zn(OTf)2 catalysed indolylation and pyrrolylation of isatins. A preliminary biochemical assay of the synthesized molecules in rodent models were performed to estimate the serum glutamate oxaloacetate transaminase and malondialdehyde levels.

  11. Revisiting the Brønsted acid catalysed hydrolysis kinetics of polymeric carbohydrates in ionic liquids by in situ ATR-FTIR spectroscopy

    DEFF Research Database (Denmark)

    Kunov-Kruse, Andreas Jonas; Riisager, Anders; Shunmugavel, Saravanamurugan;

    2013-01-01

    A new versatile method to measure rates and determine activation energies for the Brønsted acid catalysed hydrolysis of cellulose and cellobiose (and other polymeric carbohydrates) in ionic liquids is demonstrated by following the C–O stretching band of the glycoside bond with in situ ATR-FTIR. A...

  12. Appearance and distribution of regioisomers in metallo- and serine-protease-catalysed acylation of sucrose in N,N-dimethylformamide

    DEFF Research Database (Denmark)

    Lie, Aleksander; Meyer, Anne S.; Pedersen, Lars Haastrup

    2014-01-01

    The appearance and distribution of monoester regioisomers were investigated in the virtually irreversible acylation of sucrose with the enol ester, vinyl laurate, as acyl donor catalysed by serine proteases and a metalloprotease in the hydrophilic, aprotic solvent N,N-dimethylformamide. Sucrose...

  13. Palladium-Catalysed Enantioselective Conjugate Addition of Aromatic Amines to α,β-Unsaturated N-Imides. Effect of the Chelating Moiety

    NARCIS (Netherlands)

    Phua, Pim Huat; Vries, Johannes G. de; Hii, King Kuok

    2005-01-01

    Palladium-catalysed enantioselective additions of aromatic amines to α,β-unsaturated N-imides are reported. The N-substituent of the Michael acceptor appears to have an unusual modulating effect on the amine activity. The effects of introducing different substituents are examined. Overall, the yield

  14. Partial Splenic Artery Embolization

    Directory of Open Access Journals (Sweden)

    Gh. Shadmani

    2010-05-01

    Full Text Available Background/Objective: Hypersplenism often accompanies chronic liver disease and splenomegaly is one of the four cardinal signs of hypersplenism, the other three being cytopenia, normal or hyperplastic bone marrow and response splenectomy. Surgical splenectomy is the traditional treatment."nIn the recent years, partial splenic embolization has been widely used in patients with hypersplenism and cirrhosis.This study was conducted to assess the safety and efficacy of partial splenic embolization using PVA (poly vinyl alcohol and steel coil in the management of hypersplenism."nPatients and Methods: Between Aban 1387 and Aban 1388, ten patients with hypersplenism related hematologic abnormalities (leukopenia, thrombocytopenia, variceal hemorrhage or other sequels underwent partial splenic embolization with PVA and coil. A comparison between pre-procedure and post-procedure lab data, endoscopy and splenic volumetery was done."nResults: All patients showed dramatic improvement in platelet and leukocyte counts. Platelet and leukocyte counts remained at an appropriate level during the follow up period. In one patient after one year progressive decline in the platelet count was noted, however the values remained significantly higher than before PSE (70000 vs 15000."nAlmost all patients had problems related to post embolization syndrome. In one patient severe pain was noted that lasted nearly ten days, in the other patients, pain was less severe. No significant complication (splenic abscess, pancreatitis, portal vein thrombosis developed in this study."nConclusion: The efficacy of PSE observed in our study confirms the results of previous studies in pa-tients with hypersplenism. This safe, fast method can be used bridging therapy for cirrhotic patients waiting for liver transplantation. Hematological response is related to the extension of embolization.

  15. Partially informed noise traders

    OpenAIRE

    Aase, Knut K.; Bjuland, Terje; Øksendal, Bernt

    2012-01-01

    The single auction equilibrium of Kyle’s (1985) is studied, in which noise traders may be partially informed, or alternatively they can be manipulated. Unlike Kyle’s assumption that the quantity traded by the noise traders is independent of the asset value, we assume that the noise traders are able to correlate their trade with the true price. This has several implications for the equilibrium, one being that the informed trader’s expected profits decrease as the noise traders’ ability to corr...

  16. Partial model checking

    DEFF Research Database (Denmark)

    Andersen, Henrik Reif

    1995-01-01

    A major obstacle in applying finite-state model checking to the verification of large systems is the combinatorial explosion of the state space arising when many loosely coupled parallel processes are considered. The problem also known as the state-explosion problem has been attacked from various...... sides. This paper presents a new approach based on partial model checking where parts of the concurrent system are gradually removed while transforming the specification accordingly. When the intermediate specifications constructed in this manner can be kept small, the state-explosion problem is avoided...

  17. Partial Dynamical Symmetries

    CERN Document Server

    Leviatan, A

    2010-01-01

    This overview focuses on the notion of partial dynamical symmetry (PDS), for which a prescribed symmetry is obeyed by a subset of solvable eigenstates, but is not shared by the Hamiltonian. General algorithms are presented to identify interactions, of a given order, with such intermediate-symmetry structure. Explicit bosonic and fermionic Hamiltonians with PDS are constructed in the framework of models based on spectrum generating algebras. PDSs of various types are shown to be relevant to nuclear spectroscopy, quantum phase transitions and systems with mixed chaotic and regular dynamics.

  18. Partially ordered algebraic systems

    CERN Document Server

    Fuchs, Laszlo

    2011-01-01

    Originally published in an important series of books on pure and applied mathematics, this monograph by a distinguished mathematician explores a high-level area in algebra. It constitutes the first systematic summary of research concerning partially ordered groups, semigroups, rings, and fields. The self-contained treatment features numerous problems, complete proofs, a detailed bibliography, and indexes. It presumes some knowledge of abstract algebra, providing necessary background and references where appropriate. This inexpensive edition of a hard-to-find systematic survey will fill a gap i

  19. Partial differential equations

    CERN Document Server

    Sloan, D; Süli, E

    2001-01-01

    /homepage/sac/cam/na2000/index.html7-Volume Set now available at special set price ! Over the second half of the 20th century the subject area loosely referred to as numerical analysis of partial differential equations (PDEs) has undergone unprecedented development. At its practical end, the vigorous growth and steady diversification of the field were stimulated by the demand for accurate and reliable tools for computational modelling in physical sciences and engineering, and by the rapid development of computer hardware and architecture. At the more theoretical end, the analytical insight in

  20. Electrocatalytic oxidations of pyridine derivatives using Ru(IV) poly pyridine complex

    International Nuclear Information System (INIS)

    The oxidation reactions electro catalysed by bi pyridine oxo tri pyridine ruthenium perchlorate metallic complex from selected organic substrates are studied. The obtained results are compared with forecasting results showing the coherence of suggested mechanism. The substrates 2-, 2- and 4- picolines with its respective 1-oxides and 1,2 -; 1,3 - and 1,4 - dimethyl pyridine chloride salts were analysed. The oxidation of toluene as reference substrate was also studied and the mass spectra of oxidation products were interpreted. (M.C.K.)

  1. A direct approach to amines with remote stereocentres by enantioselective CuH-catalysed reductive relay hydroamination

    Science.gov (United States)

    Zhu, Shaolin; Niljianskul, Nootaree; Buchwald, Stephen L.

    2016-02-01

    Amines with remote stereocentres (stereocentres that are three or more bonds away from the C-N bond) are important structural elements in many pharmaceutical agents and natural products. However, previously reported methods to prepare these compounds in an enantioselective manner are indirect and require multistep synthesis. Here, we report a copper-hydride-catalysed, enantioselective synthesis of γ- or δ-chiral amines from readily available allylic alcohols, esters and ethers using a reductive relay hydroamination strategy (a net reductive process in which an amino group is installed at a site remote from the original carbon-carbon double bond). The protocol was suitable for substrates containing a wide range of functional groups and provided remote chiral amine products with high levels of regio- and enantioselectivity. Sequential amination of substrates containing several carbon-carbon double bonds could be achieved, demonstrating the high chemoselectivity of this process.

  2. Low-ammonia niche of ammonia-oxidizing archaea in rotating biological contactors of a municipal wastewater treatment plant

    OpenAIRE

    Sauder, L.A.; Peterse, F.; Schouten, S; Neufeld, J. D.

    2012-01-01

    The first step of nitrification is catalysed by both ammonia-oxidizing bacteria (AOB) and archaea (AOA), but physicochemical controls on the relative abundance and function of these two groups are not yet fully understood, especially in freshwater environments. This study investigated ammonia-oxidizing populations in nitrifying rotating biological contactors (RBCs) from a municipal wastewater treatment plant. Individual RBC stages are arranged in series, with nitrification at each stage creat...

  3. Synthesis of Polyamide-6/Montmorillonite Nanocomposites by Direct In-situ Polymerization Catalysed by Exchanged Clay

    Directory of Open Access Journals (Sweden)

    Djamal Eddine Kherroub

    2014-01-01

    Full Text Available The purpose of this study was to obtain polyamide-6 nanocomposites with national organically modified clay (termed 12-montmorillonite. The formation of polyamide-6 was confirmed by infrared spectroscopy (IR, the prepared nanocomposites were characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM and thermogravimetric analysis (TGA. The evolution of mechanical properties was also studied. The obtained results confirm the intercalation of molecules of salt in the clay layers, and a good interaction with the polymer, showing the formation of intercalated and/or partially exfoliated structures. The nanocomposites showed higher thermal stability compared to pure polymer, and the mechanical properties presented interesting and promising results.

  4. Kinetics and Mechanism of Acetoxymercuration and Acid-Catalysed Hydration of α-Alkylstyrenes

    Directory of Open Access Journals (Sweden)

    Oldřich Pytela

    2005-01-01

    Full Text Available Abstract: Nine α-alkylstyrenes carrying the following substituents have been synthesised: methyl, ethyl, propyl, butyl, pentyl, isobutyl, isopropyl, sec-butyl and tert-butyl. Kinetics has been measured for the reaction of these compounds with mercuric acetate in anhydrous acetic acid at 25 °C. The rate constants are very sensitive to inductive effects (ρI = –49.5 in AISE theory and steric effects (ψ = –1.59 according to Charton. These results support the presumed existence of an intermediate with an asymmetrically bound acetylmercuric cation to carbon atoms of the vinyl group of styrene. The kinetics of an acid-catalysed hydration of the above-mentioned α-alkylstyrenes were also measured in aqueous sulphuric acid at 25 °C. The derivatives exhibited kinetically a consecutive isomerisation reaction giving the more stable substituted styrenes. The values of the slope m‡m* of the dependence upon the excess acidity function (X were evaluated, and exceptionally low values were found for the butyl and pentyl substituents (1.02 and 0.73, respectively, while on the other hand tert-butyl showed an exceptionally high value (3.28. On the basis of the facts, a mechanism has been suggested for the acid-catalysed hydration, involving the reaction of a relatively stable and sterically hindered carbocation with water as the rate-limiting step of the reaction.

  5. Is Titan Partially Differentiated?

    Science.gov (United States)

    Mitri, G.; Pappalardo, R. T.; Stevenson, D. J.

    2009-12-01

    The recent measurement of the gravity coefficients from the Radio Doppler data of the Cassini spacecraft has improved our knowledge of the interior structure of Titan (Rappaport et al. 2008 AGU, P21A-1343). The measured gravity field of Titan is dominated by near hydrostatic quadrupole components. We have used the measured gravitational coefficients, thermal models and the hydrostatic equilibrium theory to derive Titan's interior structure. The axial moment of inertia gives us an indication of the degree of the interior differentiation. The inferred axial moment of inertia, calculated using the quadrupole gravitational coefficients and the Radau-Darwin approximation, indicates that Titan is partially differentiated. If Titan is partially differentiated then the interior must avoid melting of the ice during its evolution. This suggests a relatively late formation of Titan to avoid the presence of short-lived radioisotopes (Al-26). This also suggests the onset of convection after accretion to efficiently remove the heat from the interior. The outer layer is likely composed mainly of water in solid phase. Thermal modeling indicates that water could be present also in liquid phase forming a subsurface ocean between an outer ice I shell and a high pressure ice layer. Acknowledgments: This work was conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  6. Partial equilibrium model Pork

    Directory of Open Access Journals (Sweden)

    Michal MAL

    2013-03-01

    Full Text Available The paper is focused on design, specification and quantification a model of partial equilibrium in the pork meat vertical in the Czech Republic. Characterized within the analyzed relations in the commodity vertical will be demand-offer relationships on partial levels of the commodity chain on the basis of which the functional relations of the simultaneous model of the above-mentioned market will subsequently be specified. The quantified model enables the definition and description of the main determinants of the pork offer and demand. The data used was acquired from the Situation and forecast reports (MA CR, from the Annual reports on the state of agriculture (IAEI and from the public statistics (CSO, for the period from 1995-2011. With regard to respecting the simultaneous relations, the model estimate was carried out by means of the two-level method of least squares with subsequent statistic- econometrical verification. The acquired model shows sufficient robustness for market analyses and possible simulation calculations.

  7. Tutorial on Online Partial Evaluation

    OpenAIRE

    Cook, William R.; Ralf Lämmel

    2011-01-01

    This paper is a short tutorial introduction to online partial evaluation. We show how to write a simple online partial evaluator for a simple, pure, first-order, functional programming language. In particular, we show that the partial evaluator can be derived as a variation on a compositionally defined interpreter. We demonstrate the use of the resulting partial evaluator for program optimization in the context of model-driven development.

  8. Tutorial on Online Partial Evaluation

    Directory of Open Access Journals (Sweden)

    William R. Cook

    2011-09-01

    Full Text Available This paper is a short tutorial introduction to online partial evaluation. We show how to write a simple online partial evaluator for a simple, pure, first-order, functional programming language. In particular, we show that the partial evaluator can be derived as a variation on a compositionally defined interpreter. We demonstrate the use of the resulting partial evaluator for program optimization in the context of model-driven development.

  9. Completeness in Partial Differential Fields

    CERN Document Server

    Freitag, James

    2011-01-01

    We study completeness in partial differential varieties. We generalize many results from ordinary differential fields to the partial differential setting. In particular, we establish a valuative criterion for differential completeness and use it to give a new class of examples of complete partial differential varieties. We use methods from both differential algebra and model theory.

  10. Type-Directed Partial Evaluation

    DEFF Research Database (Denmark)

    Danvy, Olivier

    1998-01-01

    Type-directed partial evaluation uses a normalization function to achieve partial evaluation. These lecture notes review its background, foundations, practice, and applications. Of specific interest is the modular technique of offline and online type-directed partial evaluation in Standard ML...

  11. Type-Directed Partial Evaluation

    DEFF Research Database (Denmark)

    Danvy, Olivier

    1998-01-01

    Type-directed partial evaluation uses a normalization function to achieve partial evaluation. These lecture notes review its background, foundations, practice, and applications. Of specific interest is the modular technique of offline and online type-directed partial evaluation in Standard ML of ...

  12. Inductance loop and partial

    CERN Document Server

    Paul, Clayton R

    2010-01-01

    "Inductance is an unprecedented text, thoroughly discussing "loop" inductance as well as the increasingly important "partial" inductance. These concepts and their proper calculation are crucial in designing modern high-speed digital systems. World-renowned leader in electromagnetics Clayton Paul provides the knowledge and tools necessary to understand and calculate inductance." "With the present and increasing emphasis on high-speed digital systems and high-frequency analog systems, it is imperative that system designers develop an intimate understanding of the concepts and methods in this book. Inductance is a much-needed textbook designed for senior and graduate-level engineering students, as well as a hands-on guide for working engineers and professionals engaged in the design of high-speed digital and high-frequency analog systems."--Jacket.

  13. Elliptic partial differential equations

    CERN Document Server

    Volpert, Vitaly

    If we had to formulate in one sentence what this book is about it might be "How partial differential equations can help to understand heat explosion, tumor growth or evolution of biological species". These and many other applications are described by reaction-diffusion equations. The theory of reaction-diffusion equations appeared in the first half of the last century. In the present time, it is widely used in population dynamics, chemical physics, biomedical modelling. The purpose of this book is to present the mathematical theory of reaction-diffusion equations in the context of their numerous applications. We will go from the general mathematical theory to specific equations and then to their applications. Mathematical anaylsis of reaction-diffusion equations will be based on the theory of Fredholm operators presented in the first volume. Existence, stability and bifurcations of solutions will be studied for bounded domains and in the case of travelling waves. The classical theory of reaction-diffusion equ...

  14. Partial pressure gauges

    CERN Document Server

    Peter, G J

    2007-01-01

    The determination of partial pressures in vacuum systems is usually performed by mass spectrometers. The most common type is the QMS. Quadrupole mass spectrometers were developed decades ago and have been used by vacuum specialists as a diagnostic tool since then. In the first part of the paper the principles of these mass spectrometers are briefly reviewed together with the key features of the instruments. This is necessary to operate these instruments. In the second part the boundary conditions which arise from the application as residual gas analyser in UHV/XHV plants are described. These lead to special versions of mass spectrometers. Results obtained with these instruments and typical artefacts in mass spectra obtained in the UHV are discussed.

  15. Partial Remission Definition

    DEFF Research Database (Denmark)

    Andersen, Marie Louise Max; Hougaard, Philip; Pörksen, Sven;

    2014-01-01

    OBJECTIVE: To validate the partial remission (PR) definition based on insulin dose-adjusted HbA1c (IDAA1c). SUBJECTS AND METHODS: The IDAA1c was developed using data in 251 children from the European Hvidoere cohort. For validation, 129 children from a Danish cohort were followed from the onset....... 0.90 ± 0.03 (age + IDAA1c) at 12 months (p power of the IDAA1c measure is kept but due to the higher Boost stimulation in the Danish cohort, the specificity of the formula is lower with the chosen limits for SCP (300 pmol/L) and IDAA1c ≤9...

  16. Applied partial differential equations

    CERN Document Server

    Logan, J David

    2004-01-01

    This primer on elementary partial differential equations presents the standard material usually covered in a one-semester, undergraduate course on boundary value problems and PDEs. What makes this book unique is that it is a brief treatment, yet it covers all the major ideas: the wave equation, the diffusion equation, the Laplace equation, and the advection equation on bounded and unbounded domains. Methods include eigenfunction expansions, integral transforms, and characteristics. Mathematical ideas are motivated from physical problems, and the exposition is presented in a concise style accessible to science and engineering students; emphasis is on motivation, concepts, methods, and interpretation, rather than formal theory. This second edition contains new and additional exercises, and it includes a new chapter on the applications of PDEs to biology: age structured models, pattern formation; epidemic wave fronts, and advection-diffusion processes. The student who reads through this book and solves many of t...

  17. Fundamental partial compositeness

    CERN Document Server

    Sannino, Francesco; Tesi, Andrea; Vigiani, Elena

    2016-01-01

    We construct renormalizable Standard Model extensions, valid up to the Planck scale, that give a composite Higgs from a new fundamental strong force acting on fermions and scalars. Yukawa interactions of these particles with Standard Model fermions realize the partial compositeness scenario. Successful models exist because gauge quantum numbers of Standard Model fermions admit a minimal enough 'square root'. Furthermore, right-handed SM fermions have an SU(2)$_R$-like structure, yielding a custodially-protected composite Higgs. Baryon and lepton numbers arise accidentally. Standard Model fermions acquire mass at tree level, while the Higgs potential and flavor violations are generated by quantum corrections. We further discuss accidental symmetries and other dynamical features stemming from the new strongly interacting scalars. If the same phenomenology can be obtained from models without our elementary scalars, they would reappear as composite states.

  18. Robot-assisted partial nephrectomy: Superiority over laparoscopic partial nephrectomy.

    Science.gov (United States)

    Shiroki, Ryoichi; Fukami, Naohiko; Fukaya, Kosuke; Kusaka, Mamoru; Natsume, Takahiro; Ichihara, Takashi; Toyama, Hiroshi

    2016-02-01

    Nephron-sparing surgery has been proven to positively impact the postoperative quality of life for the treatment of small renal tumors, possibly leading to functional improvements. Laparoscopic partial nephrectomy is still one of the most demanding procedures in urological surgery. Laparoscopic partial nephrectomy sometimes results in extended warm ischemic time and severe complications, such as open conversion, postoperative hemorrhage and urine leakage. Robot-assisted partial nephrectomy exploits the advantages offered by the da Vinci Surgical System to laparoscopic partial nephrectomy, equipped with 3-D vision and a better degree in the freedom of surgical instruments. The introduction of the da Vinci Surgical System made nephron-sparing surgery, specifically robot-assisted partial nephrectomy, safe with promising results, leading to the shortening of warm ischemic time and a reduction in perioperative complications. Even for complex and challenging tumors, robotic assistance is expected to provide the benefit of minimally-invasive surgery with safe and satisfactory renal function. Warm ischemic time is the modifiable factor during robot-assisted partial nephrectomy to affect postoperative kidney function. We analyzed the predictive factors for extended warm ischemic time from our robot-assisted partial nephrectomy series. The surface area of the tumor attached to the kidney parenchyma was shown to significantly affect the extended warm ischemic time during robot-assisted partial nephrectomy. In cases with tumor-attached surface area more than 15 cm(2) , we should consider switching robot-assisted partial nephrectomy to open partial nephrectomy under cold ischemia if it is imperative. In Japan, a nationwide prospective study has been carried out to show the superiority of robot-assisted partial nephrectomy to laparoscopic partial nephrectomy in improving warm ischemic time and complications. By facilitating robotic technology, robot-assisted partial nephrectomy

  19. DEACTIVATION STUDIES ON NiO/γ-Al2O3 CATALYST FOR PARTIAL OXIDATION OF METHANE TO SYNGAS Influence of Sol-Gel Method on Catalytic Performance%甲烷部分氧化制合成气NiO/γ-Al2O3催化剂的失活研究:溶胶-凝胶法对催化性能的影响

    Institute of Scientific and Technical Information of China (English)

    张玉红; 熊国兴; 刘盛林; 盛世善; 杨维慎

    1999-01-01

    @@ The nickel-based catalyst used in partial oxidation of methane(POM)to syngas emerged as the most practical one because of the high turnover rate and inexpensive cost.However,nickel-based catalyst supported on γ-Al2O3 is usually unstable at high temperature owing either to carbon deposition[1],the loss and sintering of nickel[2] or to phase transformation.

  20. Regio- and stereoselectivity of P450-catalysed hydroxylation of steroids controlled by laboratory evolution

    Science.gov (United States)

    Kille, Sabrina; Zilly, Felipe E.; Acevedo, Juan P.; Reetz, Manfred T.

    2011-09-01

    A current challenge in synthetic organic chemistry is the development of methods that allow the regio- and stereoselective oxidative C-H activation of natural or synthetic compounds with formation of the corresponding alcohols. Cytochrome P450 enzymes enable C-H activation at non-activated positions, but the simultaneous control of both regio- and stereoselectivity is problematic. Here, we demonstrate that directed evolution using iterative saturation mutagenesis provides a means to solve synthetic problems of this kind. Using P450 BM3(F87A) as the starting enzyme and testosterone as the substrate, which results in a 1:1 mixture of the 2β- and 15β-alcohols, mutants were obtained that are 96-97% selective for either of the two regioisomers, each with complete diastereoselectivity. The mutants can be used for selective oxidative hydroxylation of other steroids without performing additional mutagenesis experiments. Molecular dynamics simulations and docking experiments shed light on the origin of regio- and stereoselectivity.