WorldWideScience

Sample records for catalytic efficient form

  1. Catalytic efficiency of designed catalytic proteins.

    Science.gov (United States)

    Korendovych, Ivan V; DeGrado, William F

    2014-08-01

    The de novo design of catalysts that mimic the affinity and specificity of natural enzymes remains one of the Holy Grails of chemistry. Despite decades of concerted effort we are still unable to design catalysts as efficient as enzymes. Here we critically evaluate approaches to (re)design of novel catalytic function in proteins using two test cases: Kemp elimination and ester hydrolysis. We show that the degree of success thus far has been modest when the rate enhancements seen for the designed proteins are compared with the rate enhancements by small molecule catalysts in solvents with properties similar to the active site. Nevertheless, there are reasons for optimism: the design methods are ever improving and the resulting catalyst can be efficiently improved using directed evolution.

  2. Reversible tetramerization of human TK1 to the high catalytic efficient form is induced by pyrophosphate, in addition to tripolyphosphates, or high enzyme concentration

    DEFF Research Database (Denmark)

    Munch-Petersen, Birgitte

    2009-01-01

    of ATP is necessary for tetramerisation and how the reaction velocity is influenced by the enzyme concentration. The results show that only two or three of the phosphate groups of ATP are necessary for tetramerisation, and that kinetics and tetramerisation are closely related. Furthermore, enzyme...... concentration was found to have a pivotal effect on catalytic efficiency.......Thymidine kinase (TK1) is a key enzyme in the salvage pathway of deoxyribonucleotide metabolism catalyzing the first step in the synthesis of dTTP by the transfer of a gamma-phosphate group from a nucleoside triphosphate to the 5´-hydroxyl group of thymidine forming dTMP. Human TK1 is cytosolic...

  3. Low efficiency deasphalting and catalytic cracking

    International Nuclear Information System (INIS)

    This patent describes a process for converting an asphaltene and metals containing heavy hydrocarbon feed to lighter, more valuable products the metals comprising Ni and V. It comprises: demetallizing the feed by deasphalting the feed in a solvent deasphalting means operating at solvent deasphalting conditions including a solvent: feed volume ratio of about 1:1 to 4:1, using a solvent selected from the group of C4 to 400 degrees F. hydrocarbons and mixtures thereof; recovering from the solvent rich fraction a demetallized oil intermediate product, having a boiling range and containing at least 10 wt.% of the asphaltenes, and 5 to 30% of the Ni and V, and at least 10 wt.% of the solvent present in the solvent rich phase produced in the deasphalting means; catalytically cracking the demetallized oil intermediate product in a catalytic cracking means operating at catalytic cracking conditions to produce a catalytically cracked product vapor fraction having a lower boiling range than the boiling range of the demetallized oil intermediate product; and fractionating the catalytically cracked product in a fractionation means to produce catalytically cracked product fractions

  4. An efficient catalytic method for fulvene synthesis

    OpenAIRE

    Coşkun, Necdet; Erden, Ihsan

    2011-01-01

    The effects of the nature and amount of base, substrate structure, amount of added water and solvent on the condensation of carbonyl compounds with cyclopentadiene in the presence of secondary amines were investigated. Based on these studies, a new efficient and green synthesis of fulvenes was developed.

  5. Immunological and catalytic quantitation of splenic glucocerebrosidase from the three clinical forms of Gaucher disease.

    Science.gov (United States)

    Pentchev, P G; Neumeyer, B; Svennerholm, L; Groth, C G; Brady, R O

    1983-07-01

    The enzymatic activity of glucocerebrosidase in splenic extracts of the adult nonneurological form of Gaucher disease (type I) was 15% +/- 7% of normal, and the titer of enzyme cross-reacting material (ECRM) in these spleens was 54% +/- 9% of normal. The titer of ECRM in splenic extracts of tissues obtained from patients with the neurological forms of Gaucher disease (types II and III) was essentially the same as in type I Gaucher spleens (59% +/- 10% of normal), but the measurable catalytic activity of glucocerebrosidase in these spleens was substantially lower than that found in type I Gaucher spleens (2.3% +/- 0.6% of normal). Thus, the attentuated glucocerebrosidase activity in spleens from all three forms of Gaucher disease appears to stem from a structurally mutated enzyme that is altered in its catalytic efficiency and possibly in its antigenic expression. PMID:6881138

  6. Solar efficiency of a photo catalytic nonwoven: dye removal applications

    Energy Technology Data Exchange (ETDEWEB)

    Guillard, C.; Disdier, J.; Herrmann, J. M.; Monnet, C.; Dussaud, J.; Malato, S.; Blanco, J.

    2003-07-01

    A specially designed titania photo catalyst was prepared by coating Ahlstrom non-woven paper, used as a flexible photo catalytic support, with Millennium anatase PC50 and PC500 at different mass coatings. Several types of reactants were treated: formetanate (pesticide), Remazole (azo-dye), Amaranth (azo-dye) and Methylene Blue (model dye). Supported catalysts installed in a new solar photo reactor (STEP) were compared to the well-known CPCs working with slurries (0.5 g/L) of the same catalysts. Efficiency of both photo catalytic system was very similar for formetanate removal but not for dye degradation, for which the CPC was more efficient. Solar UV light adsorption by dyes is proposed as the reason for these results. (Author) 12 refs.

  7. Multiscale-tailored bioelectrode surfaces for optimized catalytic conversion efficiency.

    Science.gov (United States)

    Bon Saint Côme, Yémima; Lalo, Hélène; Wang, Zhijie; Etienne, Mathieu; Gajdzik, Janine; Kohring, Gert-Wieland; Walcarius, Alain; Hempelmann, Rolf; Kuhn, Alexander

    2011-10-18

    We describe the elaboration of a multiscale-tailored bioelectrocatalytic system. The combination of two enzymes, D-sorbitol dehydrogenase and diaphorase, is studied with respect to the oxidation of D-sorbitol as a model system. The biomolecules are immobilized in an electrodeposited paint (EDP) layer. Reproducible and efficient catalysis of D-sorbitol oxidation is recorded when this system is immobilized on a gold electrode modified by a self-assembled monolayer of 4-carboxy-(2,5,7-trinitro-9-fluorenylidene)malonitrile used as a mediator. The insertion of mediator-modified gold nanoparticles into the EDP film increases significantly the active surface area for the catalytic reaction, which can be further enhanced when the whole system is immobilized in macroporous gold electrodes. This multiscale architecture finally leads to a catalytic device with optimized efficiency for potential use in biosensors, bioelectrosynthesis, and biofuel cells.

  8. Thrombomodulin Binding Selects the Catalytically Active Form of Thrombin.

    Science.gov (United States)

    Handley, Lindsey D; Treuheit, Nicholas A; Venkatesh, Varun J; Komives, Elizabeth A

    2015-11-01

    Human α-thrombin is a serine protease with dual functions. Thrombin acts as a procoagulant, cleaving fibrinogen to make the fibrin clot, but when bound to thrombomodulin (TM), it acts as an anticoagulant, cleaving protein C. A minimal TM fragment consisting of the fourth, fifth, and most of the sixth EGF-like domain (TM456m) that has been prepared has much improved solubility, thrombin binding capacity, and anticoagulant activity versus those of previous TM456 constructs. In this work, we compare backbone amide exchange of human α-thrombin in three states: apo, D-Phe-Pro-Arg-chloromethylketone (PPACK)-bound, and TM456m-bound. Beyond causing a decreased level of amide exchange at their binding sites, TM and PPACK both cause a decreased level of amide exchange in other regions including the γ-loop and the adjacent N-terminus of the heavy chain. The decreased level of amide exchange in the N-terminus of the heavy chain is consistent with the historic model of activation of serine proteases, which involves insertion of this region into the β-barrel promoting the correct conformation of the catalytic residues. Contrary to crystal structures of thrombin, hydrogen-deuterium exchange mass spectrometry results suggest that the conformation of apo-thrombin does not yet have the N-terminus of the heavy chain properly inserted for optimal catalytic activity, and that binding of TM allosterically promotes the catalytically active conformation. PMID:26468766

  9. Process of forming catalytic surfaces for wet oxidation reactions

    Science.gov (United States)

    Jagow, R. B. (Inventor)

    1977-01-01

    A wet oxidation process was developed for oxidizing waste materials, comprising dissolved ruthenium salt in a reactant feed stream containing the waste materials. The feed stream is introduced into a reactor, and the reactor contents are then raised to an elevated temperature to effect deposition of a catalytic surface of ruthenium black on the interior walls of the reactor. The feed stream is then maintained in the reactor for a period of time sufficient to effect at least partial oxidation of the waste materials.

  10. An Efficient Catalytic DNA that Cleaves L-RNA.

    Directory of Open Access Journals (Sweden)

    Kha Tram

    Full Text Available Many DNAzymes have been isolated from synthetic DNA pools to cleave natural RNA (D-RNA substrates and some have been utilized for the design of aptazyme biosensors for bioanalytical applications. Even though these biosensors perform well in simple sample matrices, they do not function effectively in complex biological samples due to ubiquitous RNases that can efficiently cleave D-RNA substrates. To overcome this issue, we set out to develop DNAzymes that cleave L-RNA, the enantiomer of D-RNA, which is known to be completely resistant to RNases. Through in vitro selection we isolated three L-RNA-cleaving DNAzymes from a random-sequence DNA pool. The most active DNAzyme exhibits a catalytic rate constant ~3 min-1 and has a structure that contains a kissing loop, a structural motif that has never been observed with D-RNA-cleaving DNAzymes. Furthermore we have used this DNAzyme and a well-known ATP-binding DNA aptamer to construct an aptazyme sensor and demonstrated that this biosensor can achieve ATP detection in biological samples that contain RNases. The current work lays the foundation for exploring RNA-cleaving DNAzymes for engineering biosensors that are compatible with complex biological samples.

  11. Investigation of the By-products Formed during the Catalytic Synthesis of 4,4'-Methylenedimethyldiphenylcarbamate

    Institute of Scientific and Technical Information of China (English)

    QIU, Ze-Gang; WANG, Jun-Wei; KANG, Mao-Qing; LI, Qi-Feng; DU, Hui; WANG, Xin-Kui

    2007-01-01

    The structures of the by-products formed during the catalytic synthesis of 4,4'-methylenedimethyldiphenylcarbamate (MDC) by the reaction of 4,4'-methylenedianiline (MDA) with dimethyl carbonate (DMC) were identified and then the mechanisms of their formation were proposed.

  12. Catalytic ozonation of oxalate with a cerium supported palladium oxide: An efficient degradation not relying on hydroxyl radical oxidation

    KAUST Repository

    Zhang, Tao

    2011-11-01

    The cerium supported palladium oxide (PdO/CeO 2) at a low palladium loading was found very effective in catalytic ozonation of oxalate, a probe compound that is difficult to be efficiently degraded in water with hydroxyl radical oxidation and one of the major byproducts in ozonation of organic matter. The oxalate was degraded into CO 2 during the catalytic ozonation. The molar ratio of oxalate degraded to ozone consumption increased with increasing catalyst dose and decreasing ozone dosage and pH under the conditions of this study. The maximum molar ratio reached around 1, meaning that the catalyst was highly active and selective for oxalate degradation in water. The catalytic ozonation, which showed relatively stable activity, does not promote hydroxyl radical generation from ozone. Analysis with ATR-FTIR and in situ Raman spectroscopy revealed that 1) oxalate was adsorbed on CeO 2 of the catalyst forming surface complexes, and 2) O 3 was adsorbed on PdO of the catalyst and further decomposed to surface atomic oxygen (*O), surface peroxide (*O 2), and O 2 gas in sequence. The results indicate that the high activity of the catalyst is related to the synergetic function of PdO and CeO 2 in that the surface atomic oxygen readily reacts with the surface cerium-oxalate complex. This kind of catalytic ozonation would be potentially effective for the degradation of polar refractory organic pollutants and hydrophilic natural organic matter. © 2011 American Chemical Society.

  13. Surface Catalytic Efficiency of Advanced Carbon Carbon Candidate Thermal Protection Materials for SSTO Vehicles

    Science.gov (United States)

    Stewart, David A.

    1996-01-01

    The catalytic efficiency (atom recombination coefficients) for advanced ceramic thermal protection systems was calculated using arc-jet data. Coefficients for both oxygen and nitrogen atom recombination on the surfaces of these systems were obtained to temperatures of 1650 K. Optical and chemical stability of the candidate systems to the high energy hypersonic flow was also demonstrated during these tests.

  14. Improving the Enzyme Catalytic Efficiency Using Ionic Liquids with Kosmotropic Anions

    Institute of Scientific and Technical Information of China (English)

    ZHAO, Hua; CAMPBELL, Sophia; SOLOMON, Jonathan; SONG, Zhi-Yan; OLUBAJO, Olarongbe

    2006-01-01

    The kosmotropicity of cations and anions in ionic liquids has a strong influence on the enzyme catalytic efficiency in aqueous environments. The kosmotropic anion CF3COO- seemed to activate the protease, and the chaotropic anions tended to destabilize the enzyme.

  15. Towards engineering nanoporous platinum thin films for highly efficient catalytic applications

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Hyun Young; Chun, Hyun Kyung; Jung, Yung Joon [Department of Mechanical and Industrial Engineering, Northeastern University, Boston, Massachusetts (United States); Kim, Do Hyung; Kim, Sang Hoon; Lim, Chae Sun; Byun, Ji Young [Functional Materials Center, Korea Institute of Science and Technology, Haweolgok-dong, Sungbuk-gu, Seoul (Korea, Republic of)

    2011-11-15

    Porous metals attract significant interest for use in diverse electrochemical catalytic applications. However the fabrication of scalable and controlled porous metal structures on the nanoscale, particularly with highly catalytic pure Pt, still remains a significant challenge. We demonstrate highly engineered nanoporous Pt thin films by the dealloying of a Pt-Si binary alloy system with a predetermined alloy composition. Controlled pore dimensions and nanostructures are obtained by tailoring the Pt-Si alloy composition followed by selective Si etching. As a result, isotropic open nanopores are formed in continuous Pt ligaments and the porosity becomes larger on increasing the Si/Pt atomic ratio, which leads to the formation of a higher surface area and active catalytic sites. The formed nanoporous Pt film shows a 32-times-higher catalytic activity than Pt/C catalysts, with a high current density and low charge-transfer resistance during methanol electro-oxidation. The results reported here open up possibilities to develop high-performance and reliable catalytic electrodes in energy and environmental applications. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Penternary chalcogenides nanocrystals as catalytic materials for efficient counter electrodes in dye-synthesized solar cells

    Science.gov (United States)

    Özel, Faruk; Sarılmaz, Adem; İstanbullu, Bilal; Aljabour, Abdalaziz; Kuş, Mahmut; Sönmezoğlu, Savaş

    2016-01-01

    The penternary chalcogenides Cu2CoSn(SeS)4 and Cu2ZnSn(SeS)4 were successfully synthesized by hot-injection method, and employed as a catalytic materials for efficient counter electrodes in dye-synthesized solar cells (DSSCs). The structural, compositional, morphological and optical properties of these pentenary semiconductors were characterized by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), energy-dispersive spectrometer (EDS) and ultraviolet-visible (UV–Vis) spectroscopy. The Cu2CoSn(SeS)4 and Cu2ZnSn(SeS)4 nanocrystals had a single crystalline, kesterite phase, adequate stoichiometric ratio, 18–25 nm particle sizes which are forming nanospheres, and band gap energy of 1.18 and 1.45 eV, respectively. Furthermore, the electrochemical impedance spectroscopy and cyclic voltammograms indicated that Cu2CoSn(SeS)4 nanocrystals as counter electrodes exhibited better electrocatalytic activity for the reduction of iodine/iodide electrolyte than that of Cu2ZnSn(SeS)4 nanocrystals and conventional platinum (Pt). The photovoltaic results demonstrated that DSSC with a Cu2CoSn(SeS)4 nanocrystals-based counter electrode achieved the best efficiency of 6.47%, which is higher than the same photoanode employing a Cu2ZnSn(SeS)4 nanocrystals (3.18%) and Pt (5.41%) counter electrodes. These promising results highlight the potential application of penternary chalcogen Cu2CoSn(SeS)4 nanocrystals in low-cost, high-efficiency, Pt-free DSSCs. PMID:27380957

  17. Penternary chalcogenides nanocrystals as catalytic materials for efficient counter electrodes in dye-synthesized solar cells.

    Science.gov (United States)

    Özel, Faruk; Sarılmaz, Adem; İstanbullu, Bilal; Aljabour, Abdalaziz; Kuş, Mahmut; Sönmezoğlu, Savaş

    2016-01-01

    The penternary chalcogenides Cu2CoSn(SeS)4 and Cu2ZnSn(SeS)4 were successfully synthesized by hot-injection method, and employed as a catalytic materials for efficient counter electrodes in dye-synthesized solar cells (DSSCs). The structural, compositional, morphological and optical properties of these pentenary semiconductors were characterized by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), energy-dispersive spectrometer (EDS) and ultraviolet-visible (UV-Vis) spectroscopy. The Cu2CoSn(SeS)4 and Cu2ZnSn(SeS)4 nanocrystals had a single crystalline, kesterite phase, adequate stoichiometric ratio, 18-25 nm particle sizes which are forming nanospheres, and band gap energy of 1.18 and 1.45 eV, respectively. Furthermore, the electrochemical impedance spectroscopy and cyclic voltammograms indicated that Cu2CoSn(SeS)4 nanocrystals as counter electrodes exhibited better electrocatalytic activity for the reduction of iodine/iodide electrolyte than that of Cu2ZnSn(SeS)4 nanocrystals and conventional platinum (Pt). The photovoltaic results demonstrated that DSSC with a Cu2CoSn(SeS)4 nanocrystals-based counter electrode achieved the best efficiency of 6.47%, which is higher than the same photoanode employing a Cu2ZnSn(SeS)4 nanocrystals (3.18%) and Pt (5.41%) counter electrodes. These promising results highlight the potential application of penternary chalcogen Cu2CoSn(SeS)4 nanocrystals in low-cost, high-efficiency, Pt-free DSSCs. PMID:27380957

  18. Penternary chalcogenides nanocrystals as catalytic materials for efficient counter electrodes in dye-synthesized solar cells

    Science.gov (United States)

    Özel, Faruk; Sarılmaz, Adem; Istanbullu, Bilal; Aljabour, Abdalaziz; Kuş, Mahmut; Sönmezoğlu, Savaş

    2016-07-01

    The penternary chalcogenides Cu2CoSn(SeS)4 and Cu2ZnSn(SeS)4 were successfully synthesized by hot-injection method, and employed as a catalytic materials for efficient counter electrodes in dye-synthesized solar cells (DSSCs). The structural, compositional, morphological and optical properties of these pentenary semiconductors were characterized by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), energy-dispersive spectrometer (EDS) and ultraviolet-visible (UV–Vis) spectroscopy. The Cu2CoSn(SeS)4 and Cu2ZnSn(SeS)4 nanocrystals had a single crystalline, kesterite phase, adequate stoichiometric ratio, 18–25 nm particle sizes which are forming nanospheres, and band gap energy of 1.18 and 1.45 eV, respectively. Furthermore, the electrochemical impedance spectroscopy and cyclic voltammograms indicated that Cu2CoSn(SeS)4 nanocrystals as counter electrodes exhibited better electrocatalytic activity for the reduction of iodine/iodide electrolyte than that of Cu2ZnSn(SeS)4 nanocrystals and conventional platinum (Pt). The photovoltaic results demonstrated that DSSC with a Cu2CoSn(SeS)4 nanocrystals-based counter electrode achieved the best efficiency of 6.47%, which is higher than the same photoanode employing a Cu2ZnSn(SeS)4 nanocrystals (3.18%) and Pt (5.41%) counter electrodes. These promising results highlight the potential application of penternary chalcogen Cu2CoSn(SeS)4 nanocrystals in low-cost, high-efficiency, Pt-free DSSCs.

  19. 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

  20. Toward efficient urban form in China

    OpenAIRE

    Webster, Douglas; Bertaud, Alain; Jianming, Cai; Zhenshan, Yang

    2010-01-01

    Land efficiency in urban China is examined, using Tianjin as a case study, from the perspective of agricultural land conservation; reduction in energy use, conventional pollution, and greenhouse gas emissions; and human time savings. Issues addressed include increased scatter on the periphery, over-consumption of industrial land, over fiscal dependence on land sales, and loss of valuable agricultural and environmental services land. Policy implications discussed include the need for greater v...

  1. Ionic liquids increase the catalytic efficiency of a lipase (Lip1) from an antarctic thermophilic bacterium.

    Science.gov (United States)

    Muñoz, Patricio A; Correa-Llantén, Daniela N; Blamey, Jenny M

    2015-01-01

    Lipases catalyze the hydrolysis and synthesis of triglycerides and their reactions are widely used in industry. The use of ionic liquids has been explored in order to improve their catalytic properties. However, the effect of these compounds on kinetic parameters of lipases has been poorly understood. A study of the kinetic parameters of Lip1, the most thermostable lipase from the supernatant of the strain ID17, a thermophilic bacterium isolated from Deception Island, Antarctica, and a member of the genus Geobacillus is presented. Kinetic parameters of Lip1 were modulated by the use of ionic liquids BmimPF6 and BmimBF4. The maximum reaction rate of Lip1 was improved in the presence of both salts. The highest effect was observed when BmimPF6 was added in the reaction mix, resulting in a higher hydrolytic activity and in a modulation of the catalytic efficiency of the enzyme. However, the catalytic efficiency did not change in the presence of BmimBF4. The increase of the reaction rates of Lip1 promoted by these ionic liquids could be related to possible changes in the Lip1 structure. This effect was measured by quenching of tryptophan fluorescence of the enzyme, when it was incubated with each liquid salt. In conclusion, the hydrolytic activity of Lip1 is modulated by the ionic liquids BmimBF4 and BmimPF6, improving the reaction rate and the catalytic efficiency of this enzyme when BmimPF6 was used. This effect is probably due to changes in the structure of Lip1 induced by the presence of these ionic liquids, stimulating its catalytic activity.

  2. Ionic liquids increase the catalytic efficiency of a lipase (Lip1) from an antarctic thermophilic bacterium.

    Science.gov (United States)

    Muñoz, Patricio A; Correa-Llantén, Daniela N; Blamey, Jenny M

    2015-01-01

    Lipases catalyze the hydrolysis and synthesis of triglycerides and their reactions are widely used in industry. The use of ionic liquids has been explored in order to improve their catalytic properties. However, the effect of these compounds on kinetic parameters of lipases has been poorly understood. A study of the kinetic parameters of Lip1, the most thermostable lipase from the supernatant of the strain ID17, a thermophilic bacterium isolated from Deception Island, Antarctica, and a member of the genus Geobacillus is presented. Kinetic parameters of Lip1 were modulated by the use of ionic liquids BmimPF6 and BmimBF4. The maximum reaction rate of Lip1 was improved in the presence of both salts. The highest effect was observed when BmimPF6 was added in the reaction mix, resulting in a higher hydrolytic activity and in a modulation of the catalytic efficiency of the enzyme. However, the catalytic efficiency did not change in the presence of BmimBF4. The increase of the reaction rates of Lip1 promoted by these ionic liquids could be related to possible changes in the Lip1 structure. This effect was measured by quenching of tryptophan fluorescence of the enzyme, when it was incubated with each liquid salt. In conclusion, the hydrolytic activity of Lip1 is modulated by the ionic liquids BmimBF4 and BmimPF6, improving the reaction rate and the catalytic efficiency of this enzyme when BmimPF6 was used. This effect is probably due to changes in the structure of Lip1 induced by the presence of these ionic liquids, stimulating its catalytic activity. PMID:25425150

  3. Eco efficiency of urban form and transportation

    International Nuclear Information System (INIS)

    Urban planning and transportation system solutions and decisions have a large-scale significance for eco efficiency, the consumption of energy and other natural resources, the production of greenhouse gas and other emissions, and the costs caused by communities.Planning solutions may impact on greenhouse gas emissions by 10 % at regional level, by 20 % at local community level and even by 200 % at local dwelling area level. Impact on emissions caused by transportation is even bigger: at least double compared to the impact on total emissions. Similarly large impacts can be seen concerning consumption of energy and other natural resources as well as costs.The most important factors in sustainable urban and transportation planning are at dwelling area level: location, structure, building density, house types, space heating systems, at community and regional level: area density, energy consumption and production systems, location of and distances between dwellings, working places and services, transportation systems, possibilities of walking and cycling, availability of public transport, and necessity for use of private cars. The presentation is based on the author's research and case studies from 1992 to 2006. The assessment method EcoBalance was developed to assess sustainability of communities and it has been applied at different planning levels: regional plans, local master plans and detailed plans. The EcoBalance model estimates the total consumption of energy and other natural resources, the production of emissions and wastes and the costs caused directly and indirectly by communities on a life-cycle basis

  4. [Isolation and catalytic properties of the soluble monomeric form of inorganic pyrophosphatase from baker's yeast].

    Science.gov (United States)

    Kasho, V N; Bakuleva, N P; Baĭkov, A A; Avaeva, S M

    1982-06-01

    Data from sedimentation analysis suggest that modification of about 40% of free amino groups of inorganic pyrophosphatase by maleic anhydride, pH 10.5, results in a loss of the enzyme ability to form dimers at neutral values of pH. The specific activity of monomeric pyrophosphatase is 50-80% of that of the dimeric form. The monomer has a pH optimum of about 7, requires metal ions for activation of both enzyme and substrate and is capable of exergonic synthesis of PPi in the active center. The enzyme binding to PPi is strongly stabilized by fluoride. The experimental data indicate that the individual subunit of inorganic pyrophosphatase possesses all the main catalytic properties of native dimeric molecule. PMID:6126223

  5. Efficiency enhancement of wood stove integrated with catalytic combustor and modified chimney

    Directory of Open Access Journals (Sweden)

    G. Murali

    2014-12-01

    Full Text Available Domestic wood combustion produces smoke that is harmful to human health and increases fine particle level in the atmosphere. Some necessary changes in the design are essential in the domestic wood stove in order to improve the performance and scale down the emission. In this work, an improved wood stove integrated with the catalytic combustor and modified chimney that uses wood as fuel has been experimentally evaluated. Water boiling test, cooking test and emission test have been conducted to evaluate the performance of the stove. It was observed that emission has been considerably controlled because of the incorporation of catalytic combustor. The heat losses through the walls of stove decresed by providing ceramic insulation. The thermal efficiency value of an improved wood stove obtained was 41.18% and this is 31.52% higher than traditional stove. The improved wood stove results better performance than a traditional wood stove.

  6. Evaluating Agricultural Banking Efficiency Using the Fourier Flexible Functional Form

    OpenAIRE

    Yu, Yingzhuo; Escalante, Cesar L.; Deng, Xiaohui

    2007-01-01

    This study applied more flexible cost functional form, Fourier Flexible Functional Form, and tested the validity of the Translog cost functional form as to estimate the cost function incorporating risk and loan's quality for banking industry. Meanwhile, the study extended four different cost efficiency measures for banking industry not only among different sized banks but also between commercial banks and agricultural banks. And thereafter, by evaluating these efficiency measures, banks will ...

  7. A Sustainable and Efficient Synthesis of Benzyl Phosphonates Using PEG/KI Catalytic System.

    Science.gov (United States)

    Disale, Shamrao; Kale, Sandip; Abraham, George; Kahandal, Sandeep; Sawarkar, Ashish N; Gawande, Manoj B

    2016-01-01

    An efficient and expedient protocol for the synthesis of benzyl phosphonates using KI/K2CO3 as a catalytic system and PEG-400 as benign solvent has been developed. The reaction proceeds smoothly at room temperature achieving excellent selectivity and yield of the corresponding products. The combination of PEG-400, KI, and K2CO3 in this reaction avoids the need of volatile/toxic organic solvents and reactive alkali metals or metal nanoparticles/hydrides. We believe that this benign combination (PEG-400 and KI) could be used for other related organic transformations. PMID:27579301

  8. A sustainable and efficient synthesis of benzyl phosphonates using PEG/KI catalytic system

    Science.gov (United States)

    Gawande, Manoj; Disale, Shamrao; Kale, Sandip; Abraham, George; Kahandal, Sandeep; Sawarkar, Ashish

    2016-08-01

    An efficient and expedient protocol for the synthesis of benzyl phosphonates using KI/K2CO3 as a catalytic system and PEG-400 as benign solvent has been developed. The reaction proceeds smoothly at room temperature achieving excellent selectivity and yield of the corresponding products. The combination of PEG-400, KI and K2CO3 in this reaction avoids the need of volatile/toxic organic solvents and reactive alkali metals or metal nanoparticles/hydrides. We believe that this benign combination (PEG-400 and KI) could be used for other related organic transformations.

  9. Efficiency of Different Nitrogen Forms in Buckwheat (Fagopyrum esculentum Moench

    Directory of Open Access Journals (Sweden)

    Burhan Kara

    2016-07-01

    Full Text Available The research was carried out with aim to determination the efficient of nitrogen forms (ammonium sulfate, ammonium nitrate and urea on nitrogen use efficient for buckwheat in Isparta during 2014 and 2015 years. All the examined characteristics were determined higher values in applied nitrogen forms according to non-nitrogen parcel. In compared to nitrogen forms, the highest grain yield (1456 and 1325 kg ha-1, biological yield (4873 and 4512 kg ha-1, 1000 grain weight (24.9 and 24.8 g, agronomic efficient (24.96% and 24.25%, recycling efficient (0.24% and 0.22% and utilization efficient (0.25% and 0.18% were obtained from ammonium sulfate, the highest protein content (11.37% and 12.44% and agro-physiological efficient (0.27% and 0.24% from ammonium nitrate in both years. Among the nitrogen forms weren’t significant differently in physiological efficient in both years, recycling and utilization efficient in the first year. The mineral nutrient content varied according to nitrogen forms. Generally, ammonium sulfate was positive effect to yield and some quality parameters.

  10. Testing the Weak Form Efficiency of Karachi Stock Exchange

    Directory of Open Access Journals (Sweden)

    Muhammad Arshad Haroon

    2012-12-01

    Full Text Available In an efficient market, share prices reflect all available information. The study of efficient market hypothesis helps to take right decisions related to investments. In this research,weak form efficiency has been tested of Karachi Stock Exchange—KSE covering the period of 2nd November 1991 to 2nd November 2011. Descriptive statistics indicated the absence of weak form efficiency while results of non-parametric tests, showed consistency as well. We employed non-parametric tests were KS Goodness-of-Fit test,run test and autocorrelation test to find out serial independency of the data. Results prove that KSE is not weak-form-efficient. This happens because KSE is an emerging market and there, it has been observed that information take time to be processed. Thus it can besaid that technical analysis may be applied to gain abnormal returns.

  11. SET OF CRITERIA FOR EFFICIENCY OF THE PROCESS FORMING SET OF CRITERIA FOR EFFICIENCY OF THE PROCESS FORMING

    Directory of Open Access Journals (Sweden)

    Alexander Aleksandrovich RYBANOV,

    Full Text Available Is offered the set of criteria for assessing efficiency of the process forming the answers to multiple-choice test items. To increase accuracy of computer-assisted testing results, it is suggested to assess dynamics of the process of forming the final answer using the following factors: loss of time factor and correct choice factor. The model application results show the high efficiency of suggested set of criterias

  12. Upward Trend in Catalytic Efficiency of Rare-Earth Triflate Catalysts in Friedel-Crafts Aromatic Sulfonylation Reactions

    DEFF Research Database (Denmark)

    Duus, Fritz; Le, Thach Ngoc; Nguyen, Vo Thu An

    2014-01-01

    90 % were achieved for short irradiation periods. This was the case especially for Tm(OTf)3, Yb(OTf)3, and Lu(OTf)3, of which Yb(OTf)3 was the most efficient. The upward trend in catalytic efficiency therefore correlates with the lanthanide sequence in the periodic table. The results can be explained...

  13. Rational design of organophosphorus hydrolase with high catalytic efficiency for detoxifying a V-type nerve agent.

    Science.gov (United States)

    Jeong, Young-Su; Choi, Jung Min; Kyeong, Hyun-Ho; Choi, Jae-Youl; Kim, Eui-Joong; Kim, Hak-Sung

    2014-07-01

    V-type nerve agents, known as VX, are organophosphate (OP) compounds, and show extremely toxic effects on human and animals by causing cholinergic overstimulation of synapses. The bacterial organophosphorus hydrolase (OPH) has attracted much attention for detoxifying V-type agents through hydrolysis of the P-S bond. However, low catalytic efficiency of OPH has limited the practical use of the enzyme. Here we present rational design of OPH with high catalytic efficiency for a V-type nerve agent. Based on the model structure of the enzyme and substrate docking simulation, we predicted the key residues that appear to enhance the access of the substrate to the active site of the enzyme, and constructed numerous OPH mutants. Of them, double mutant, L271/Y309A, was shown to exhibit a 150-fold higher catalytic efficiency for VX than the wild-type.

  14. Green Fabrication of Ag Coated Polyacrylonitrile Nanofibrous Composite Membrane with High Catalytic Efficiency.

    Science.gov (United States)

    Shen, Lingdi; Yu, Lina; Wang, Min; Wang, Xuefen; Zhu, Meifang; Hsiao, Benjamin S

    2015-07-01

    Ag-coated polyacrylonitrile (PAN) nanofibers have been prepared by a novel, facile and green way that combined electrospinning technique and poly(dopamine)-assisted electroless plating method. Poly(dopamine) (PDOP) was formed by oxidation polymerization of dopamine on the surface of PAN nanofibers to promote the electroless plating of silver. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectroscopy and energy dispersive X-ray spectroscopy (EDS) were used to characterize the morphology and structure of Ag/PDOP/PAN nanofibrous composite mem- brane and Ultraviolet-visible (UV-vis) Spectroscopy was used to investigate its catalytic performance. The results indicated that silver clusters composed of face-centred cubic crystal Ag with average crystallite size of about 18 nm were well distributed on the surface of dopamine-modified electrospun PAN nanofibers (PDOP/PAN). The prepared silver coated PDOP/PAN (Ag/PDOP/PAN) nanofibrous composite membrane exhibited an outstanding catalytic performance, and showed good reusabil- ity for completely degradating methylene blue (MB) dyes and reducing o-nitroaniline very quickly, respectively. PMID:26373068

  15. Studies on relative catalytic efficiencies of zinc and aluminium on nucleation of dispersed bismuth droplets

    Indian Academy of Sciences (India)

    Sanjay Chaubey

    2007-04-01

    In Zn–Bi and Al–Bi systems, both of which belong to monotectic class, dispersion of second phase particles within the matrix have been produced through rapid solidification processing (RSP) route. In order to understand relative catalytic efficiencies of Zn and Al matrices in catalyzing nucleation of Bi particles entrapped in the respective metal matrices, thermal analysis in constant program mode was performed. Thermal analyses revealed that Bi undercools by 132° in Zn matrix and by 157° in Al matrix. Thermodynamic barrier to nucleation (*) for Bi has also been calculated, which is 39.8 kcal/mole and 47.085 kcal/mole, in Zn and Al matrices, respectively at the maximum recorded undercoolings.

  16. Substrate contributions to automotive catalytic converter performance. The role of channel shape on catalyst efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Day, J.P. [Science and Technology Division, Corning Incorporated, Corning, New York (United States)

    1998-12-31

    The catalyst support plays an integral part in the performance of the automotive catalytic converter system. Although the precious metal catalyst is the primary contributor to the conversion efficiency, the substrate role is to properly distribute and support the washcoat and precious metal catalyst in order to utilize the properties of these components most fully. By optimizing the substrate properties as well as the precious metal and washcoat systems, optimum benefit from the catalyst system can be obtained. The automotive catalyst support is composed of the material and the structure. Previous papers have dealt with the materials. This paper will describe the structure of the catalyst support, specifically the channel shape, and present the structure-related heat transfer, mass transfer, and pressure drop properties for the laminar flow condition for various channel shapes. After these relationships have been established, a comparison will be made between the catalyst system performance of two of the channel shapes available commercially. 14 refs.

  17. Calculating the rate of exothermic energy release for catalytic converter efficiency monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Hepburn, J.S.; Meitzler, A.H. [Ford Motor Co., Dearborn, MI (United States)

    1995-12-31

    This paper reports on the development of a new methodology for OBD-II catalyst efficiency monitoring. Temperature measurements taken from the center of the catalyst substrate or near the exterior surface of the catalyst brick were used in conjunction with macroscopic energy balances to calculate the instantaneous rate of exothermic energy generation within the catalyst. The total calculated rate of exothermic energy release over the FTP test cycle was within 10% of the actual or theoretical value and provided a good indicator of catalyst light-off for a variety of aged catalytic converters. Normalization of the rate of exothermic energy release in the front section of the converter by the mass flow rate of air inducted through the engine was found to provide a simple yet practical means of monitoring the converter under both FTP and varying types of road driving.

  18. Malbranchea cinnamomea: A thermophilic fungal source of catalytically efficient lignocellulolytic glycosyl hydrolases and metal dependent enzymes.

    Science.gov (United States)

    Mahajan, Chhavi; Basotra, Neha; Singh, Surender; Di Falco, Marcos; Tsang, Adrian; Chadha, B S

    2016-01-01

    This study reports thermophilic fungus Malbranchea cinnamomea as an important source of lignocellulolytic enzymes. The secretome analysis using LC-MS/MS orbitrap showed that fungus produced a spectrum of glycosyl hydrolases (cellulase/hemicellulase), polysaccharide lyases (PL) and carbohydrate esterases (CE) in addition to cellobiose dehydrogenase (CDH) indicating the presence of functional classical and oxidative cellulolytic mechanisms. The protein fractions in the secretome resolved by ion exchange chromatography were analyzed for ability to hydrolyze alkali treated carrot grass (ATCG) in the presence of Mn(2+)/Cu(2+). This strategy in tandem with peptide mass fingerprinting led to identification of metal dependent protein hydrolases with no apparent hydrolytic activity, however, showed 5.7 folds higher saccharification in presence of Mn(2+). Furthermore, adding different protein fractions to commercial cellulase (Novozymes: Cellic CTec2) resulted in enhanced hydrolysis of ATCG ranging between 1.57 and 3.43 folds indicating the enzymes from M. cinnamomea as catalytically efficient. PMID:26476165

  19. Some Aspects of the Catalytic Organic Synthesis

    Institute of Scientific and Technical Information of China (English)

    Anil; K.Saikia

    2007-01-01

    1 Results Catalytic reactions are gaining importance due to its low cost, operational simplicity, high efficiency and selectivity. It is also getting much attention in green synthesis. Many useful organic reactions, including the acylation of alcohols and aldehydes, carbon-carbon, carbon-nitrogen, carbon-sulfur bond forming and oxidation reactions are carried out by catalyst. We are exploring the catalytic acylation of alcohols and aldehydes in a simple and efficient manner. Catalytic activation of unr...

  20. Testing weak-form efficiency of exchange traded funds market

    OpenAIRE

    Gerasimos G. Rompotis

    2011-01-01

    In this paper we assess the weak-form efficiency of Exchange Traded Funds market applying various parametric and non-parametric tests. The parametric tests performed concern serial correlation tests and Augmented Dickey-Fuller (ADF) unit root test while the nonparametric tests used is the Phillips-Peron (PP) unit root test. To assess ETF market efficiency, we employ full daily return historical data of a sample of 66 equity-linked ETFs traded in the U.S. stock over the period 2001-2010. The p...

  1. Improved catalytic efficiency, thermophilicity, anti-salt and detergent tolerance of keratinase KerSMD by partially truncation of PPC domain

    OpenAIRE

    Zhen Fang; Juan Zhang; Guocheng Du; Jian Chen

    2016-01-01

    The keratinase from Stenotrophomonas maltophilia (KerSMD) is known for its high activity and pH stability in keratin degradation. However, catalytic efficiency and detergent tolerability need to be improved in order to be used for industrial application. In this work, we obtained several keratinase variants with enhanced catalytic efficiency, thermophilicity, and anti-salt and detergent tolerability by partially truncating the PPC domain of KerSMD. The variants all showed improved catalytic e...

  2. Efficient control of transient wave forms to prevent spreading depolarizations

    OpenAIRE

    Dahlem, Markus A.; Schneider, Felix M.; Schoell, Eckehard

    2007-01-01

    In various neurological disorders spatio-temporal excitation patterns constitute examples of excitable behavior emerging from pathological pathways. During migraine, seizure, and stroke an initially localized pathological state can temporarily spread indicating a transition from non-excitable to excitable behavior. We investigate these transient wave forms in the generic FitzHugh-Nagumo (FHN) system of excitable media. Our goal is to define an efficient control minimizing the volume of invade...

  3. ABOUT FORMS, EFFICIENCY AND ASSESSMENT OF ENVIRONMENTAL MANAGEMENT

    Directory of Open Access Journals (Sweden)

    H. Bachev

    2015-03-01

    Full Text Available We suggest a holistic framework for analyzing, assessment and improvement of environmental management using “agrariansector” as an example. It incorporates an interdisciplinary approach (Economics, Organization, Law, Sociology, Ecology, Technology, Behavioral and Political Sciences and includes: specification of managerial actors, needs and spectrum of governing modes (institutional environment; private, collective, market, public modes at different level of decision-making (individual, farm, eco-system, local, regional, national, transnational, global; specification of critical socio-economic, natural, technological, behavioral etc. factors of managerial choice, and feasible spectrum of managerial forms; defining and assessing comparative and absolute efficiency of eco-management forms and system; improvement of forms of public intervention in eco-management.

  4. Characterization of catalytic efficiency parameters of brain cholinesterases in tropical fish.

    Science.gov (United States)

    de Assis, Caio Rodrigo Dias; Linhares, Amanda Guedes; Oliveira, Vagne Melo; França, Renata Cristina Penha; Santos, Juliana Ferreira; Marcuschi, Marina; Carvalho, Elba Verônica Matoso Maciel; Bezerra, Ranilson Souza; Carvalho, Luiz Bezerra

    2014-12-01

    Brain cholinesterases from four fish (Arapaima gigas, Colossoma macropomum, Rachycentron canadum and Oreochromis niloticus) were characterized using specific substrates and selective inhibitors. Parameters of catalytic efficiency such as activation energy (AE), k(cat) and k(cat)/k(m) as well as rate enhancements produced by these enzymes were estimated by a method using crude extracts described here. Despite the BChE-like activity, specific substrate kinetic analysis pointed to the existence of only acetylcholinesterase (AChE) in brain of the species studied. Selective inhibition suggests that C. macropomum brain AChE presents atypical activity regarding its behavior in the presence of selective inhibitors. AE data showed that the enzymes increased the rate of reactions up to 10(12) in relation to the uncatalyzed reactions. Zymograms showed the presence of AChE isoforms with molecular weights ranging from 202 to 299 kDa. Values of k(cat) and k(cat)/k(m) were similar to those found in the literature.

  5. Classical Keggin Intercalated into Layered Double Hydroxides: Facile Preparation and Catalytic Efficiency in Knoevenagel Condensation Reactions.

    Science.gov (United States)

    Jia, Yueqing; Fang, Yanjun; Zhang, Yingkui; Miras, Haralampos N; Song, Yu-Fei

    2015-10-12

    The family of polyoxometalate (POM) intercalated layered double hydroxide (LDH) composite materials has shown great promise for the design of functional materials with numerous applications. It is known that intercalation of the classical Keggin polyoxometalate (POM) of [PW12 O40 ](3-) (PW12 ) into layered double hydroxides (LDHs) is very unlikely to take place by conventional ion exchange methods due to spatial and geometrical restrictions. In this paper, such an intercalated compound of Mg0.73 Al0.22 (OH)2 [PW12 O40 ]0.04 ⋅0.98 H2 O (Mg3 Al-PW12 ) has been successfully obtained by applying a spontaneous flocculation method. The Mg3 Al-PW12 has been fully characterized by using a wide range of methods (XRD, SEM, TEM, XPS, EDX, XPS, FT-IR, NMR, BET). XRD patterns of Mg3 Al-PW12 exhibit no impurity phase usually observed next to the (003) diffraction peak. Subsequent application of the Mg3 Al-PW12 as catalyst in Knoevenagel condensation reactions of various aldehydes and ketones with Z-CH2 -Z' type substrates (ethyl cyanoacetate and malononitrile) at 60 °C in mixed solvents (V2-propanol :Vwater =2:1) demonstrated highly efficient catalytic activity. The synergistic effect between the acidic and basic sites of the Mg3 Al-PW12 composite proved to be crucial for the efficiency of the condensation reactions. Additionally, the Mg3 Al-PW12 -catalyzed Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate demonstrated the highest turnover number (TON) of 47 980 reported so far for this reaction. PMID:26337902

  6. Aroylhydrazone Cu(II Complexes in keto Form: Structural Characterization and Catalytic Activity towards Cyclohexane Oxidation

    Directory of Open Access Journals (Sweden)

    Manas Sutradhar

    2016-03-01

    Full Text Available The reaction of the Schiff base (3,5-di-tert-butyl-2-hydroxybenzylidene-2-hydroxybenzohydrazide (H3L with a copper(II salt of a base of a strong acid, i.e., nitrate, chloride or sulphate, yielded the mononuclear complexes [Cu(H2L(NO3(H2O] (1, [Cu(H2LCl]·2MeOH (2 and the binuclear complex [{Cu(H2L}2(µ-SO4]·2MeOH (3, respectively, with H2L− in the keto form. Compounds 1–3 were characterized by elemental analysis, Infrared (IR spectroscopy, Electrospray Ionisation Mass Spectrometry (ESI-MS and single crystal X-ray crystallography. All compounds act as efficient catalysts towards the peroxidative oxidation of cyclohexane to cyclohexyl hydroperoxide, cyclohexanol and cyclohexanone, under mild conditions. In the presence of an acid promoter, overall yields (based on the alkane up to 25% and a turnover number (TON of 250 (TOF of 42 h−1 after 6 h, were achieved.

  7. Aroylhydrazone Cu(II) Complexes in keto Form: Structural Characterization and Catalytic Activity towards Cyclohexane Oxidation.

    Science.gov (United States)

    Sutradhar, Manas; Alegria, Elisabete C B A; Guedes da Silva, M Fátima C; Martins, Luísa M D R S; Pombeiro, Armando J L

    2016-01-01

    The reaction of the Schiff base (3,5-di-tert-butyl-2-hydroxybenzylidene)-2-hydroxybenzohydrazide (H3L) with a copper(II) salt of a base of a strong acid, i.e., nitrate, chloride or sulphate, yielded the mononuclear complexes [Cu(H2L)(NO3)(H2O)] (1), [Cu(H2L)Cl]·2MeOH (2) and the binuclear complex [{Cu(H2L)}2(µ-SO4)]·2MeOH (3), respectively, with H2L(-) in the keto form. Compounds 1-3 were characterized by elemental analysis, Infrared (IR) spectroscopy, Electrospray Ionisation Mass Spectrometry (ESI-MS) and single crystal X-ray crystallography. All compounds act as efficient catalysts towards the peroxidative oxidation of cyclohexane to cyclohexyl hydroperoxide, cyclohexanol and cyclohexanone, under mild conditions. In the presence of an acid promoter, overall yields (based on the alkane) up to 25% and a turnover number (TON) of 250 (TOF of 42 h(-1)) after 6 h, were achieved. PMID:27043506

  8. Characterization of a soluble, catalytically active form of Escherichia coli leader peptidase: requirement of detergent or phospholipid for optimal activity.

    Science.gov (United States)

    Tschantz, W R; Paetzel, M; Cao, G; Suciu, D; Inouye, M; Dalbey, R E

    1995-03-28

    Leader peptidase is a novel serine protease in Escherichia coli, which functions to cleave leader sequences from exported proteins. Its catalytic domain extends into the periplasmic space and is anchored to the membrane by two transmembrane segments located at the N-terminal end of the protein. At present, there is no information on the structure of the catalytic domain. Here, we report on the properties of a soluble form of leader peptidase (delta 2-75), and we compare its properties to those of the wild-type enzyme. We find that the truncated leader peptidase has a kcat of 3.0 S-1 and a Km of 32 microM with a pro-OmpA nuclease A substrate. In contrast to the wild-type enzyme (pI of 6.8), delta 2-75 is water-soluble and has an acidic isoelectric point of 5.6. We also show with delta 2-75 that the replacement of serine 90 and lysine 145 with alanine residues results in a 500-fold reduction in activity, providing further evidence that leader peptidase employs a catalytic serine/lysine dyad. Finally, we find that the catalysis of delta 2-75 is accelerated by the presence of the detergent Triton X-100, regardless if the substrate is pro-OmpA nuclease A or a peptide substrate. Triton X-100 is required for optimal activity of delta 2-75 at a level far below the critical micelle concentration. Moreover, we find that E. coli phospholipids stimulate the activity of delta 2-75, suggesting that phospholipids may play an important physiological role in the catalytic mechanism of leader peptidase. PMID:7696258

  9. Effect of the Sequence of the Thermoelectric Generator and the Three-Way Catalytic Converter on Exhaust Gas Conversion Efficiency

    Science.gov (United States)

    Su, Chuqi; Tong, Naiqiang; Xu, Yuman; Chen, Shan; Liu, Xun

    2013-07-01

    The potential for thermoelectric exhaust heat recovery in vehicles has increased with recent improvements in the efficiency of thermoelectric generators (TEGs). The problem with using thermoelectric generators for vehicle applications is whether the device is compatible with the original vehicle exhaust system, which determines the quality of the exhaust gas treatment and the realization of energy conservation and emission reduction. Based on ANSYS CFX simulation analysis of the impact of two positional relationships between the TEG and three-way catalytic converter in the exhaust system on the working efficiency of both elements, it is concluded that the layout with the front three-way catalytic converter has an advantage over the other layout mode under current conditions. New ideas for an improvement program are proposed to provide the basis for further research.

  10. Syncephalastrum racemosum amine oxidase with high catalytic efficiency toward ethanolamine and its application in ethanolamine determination.

    Science.gov (United States)

    Hirano, Yoshitaka; Chonan, Keisuke; Murayama, Kazutaka; Sakasegawa, Shin-Ich; Matsumoto, Hideyuki; Sugimori, Daisuke

    2016-05-01

    Our screening study yielded a copper amine oxidase (SrAOX) from Syncephalastrum racemosum, which showed much higher affinity and catalytic efficiency toward ethanolamine (EA) than any other amine oxidase (AOX). Following purification of the enzyme to electrophoretic homogeneity from a cell-free extract, the maximum activity toward EA was detected at pH 7.2-7.5 and 45 °C. The SrAOX complementary DNA (cDNA) was composed of a 2052-bp open reading frame encoding a 683-amino acid protein with a molecular mass of 77,162 Da. The enzyme functions as a homodimer. The deduced amino acid sequence of SrAOX showed 55.3 % identity to Rhizopus delemar AOX and contains two consensus sequences of Cu-AOX, NYDY, and HHQH, suggesting SrAOX is a type 1 Cu-AOX (i.e., a topaquinone enzyme). Structural homology modeling showed that residues (112)ML(113), (141)FADTWG(146) M158, and N318 are unique, and T144 possibly characterizes the substrate specificity of SrAOX. The recombinant enzyme (rSrAOX) was produced using Escherichia coli. Steady-state kinetic analysis of rSrAOX activity toward EA (pH 7.5 and 45 °C) gave K m and k cat values of 0.848 ± 0.009 mM and 9.11 ± 0.13 s(-1), respectively. The standard curves were linear between 0.1 and 2 mM EA, and 10 μg mL(-1)-2.5 mg mL(-1) (15 μM-3.6 mM) phosphatidylethanolamine using Streptomyces chromofuscus phospholipase D, respectively, was sufficiently sensitive for clinical use. PMID:26691518

  11. Syncephalastrum racemosum amine oxidase with high catalytic efficiency toward ethanolamine and its application in ethanolamine determination.

    Science.gov (United States)

    Hirano, Yoshitaka; Chonan, Keisuke; Murayama, Kazutaka; Sakasegawa, Shin-Ich; Matsumoto, Hideyuki; Sugimori, Daisuke

    2016-05-01

    Our screening study yielded a copper amine oxidase (SrAOX) from Syncephalastrum racemosum, which showed much higher affinity and catalytic efficiency toward ethanolamine (EA) than any other amine oxidase (AOX). Following purification of the enzyme to electrophoretic homogeneity from a cell-free extract, the maximum activity toward EA was detected at pH 7.2-7.5 and 45 °C. The SrAOX complementary DNA (cDNA) was composed of a 2052-bp open reading frame encoding a 683-amino acid protein with a molecular mass of 77,162 Da. The enzyme functions as a homodimer. The deduced amino acid sequence of SrAOX showed 55.3 % identity to Rhizopus delemar AOX and contains two consensus sequences of Cu-AOX, NYDY, and HHQH, suggesting SrAOX is a type 1 Cu-AOX (i.e., a topaquinone enzyme). Structural homology modeling showed that residues (112)ML(113), (141)FADTWG(146) M158, and N318 are unique, and T144 possibly characterizes the substrate specificity of SrAOX. The recombinant enzyme (rSrAOX) was produced using Escherichia coli. Steady-state kinetic analysis of rSrAOX activity toward EA (pH 7.5 and 45 °C) gave K m and k cat values of 0.848 ± 0.009 mM and 9.11 ± 0.13 s(-1), respectively. The standard curves were linear between 0.1 and 2 mM EA, and 10 μg mL(-1)-2.5 mg mL(-1) (15 μM-3.6 mM) phosphatidylethanolamine using Streptomyces chromofuscus phospholipase D, respectively, was sufficiently sensitive for clinical use.

  12. Energy Efficient Catalytic Activation of Hydrogen peroxide for Green Chemical Processes: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Terrence J.; Horwitz, Colin

    2004-11-12

    A new, highly energy efficient approach for using catalytic oxidation chemistry in multiple fields of technology has been pursued. The new catalysts, called TAML® activators, catalyze the reactions of hydrogen peroxide and other oxidants for the exceptionally rapid decontamination of noninfectious simulants (B. atrophaeus) of anthrax spores, for the energy efficient decontamination of thiophosphate pesticides, for the facile, low temperature removal of color and organochlorines from pulp and paper mill effluent, for the bleaching of dyes from textile mill effluents, and for the removal of recalcitrant dibenzothiophene compounds from diesel and gasoline fuels. Highlights include the following: 1) A 7-log kill of Bacillus atrophaeus spores has been achieved unambiguously in water under ambient conditions within 15 minutes. 2) The rapid total degradation under ambient conditions of four thiophosphate pesticides and phosphonate degradation intermediates has been achieved on treatment with TAML/peroxide, opening up potential applications of the decontamination system for phosphonate structured chemical warfare agents, for inexpensive, easy to perform degradation of stored and aged pesticide stocks (especially in Africa and Asia), for remediation of polluted sites and water bodies, and for the destruction of chemical warfare agent stockpiles. 3) A mill trial conducted in a Pennsylvanian bleached kraft pulp mill has established that TAML catalyst injected into an alkaline peroxide bleach tower can significantly lower color from the effluent stream promising a new, more cost effective, energy-saving approach for color remediation adding further evidence of the value and diverse engineering capacity of the approach to other field trials conducted on effluent streams as they exit the bleach plant. 4) Dibenzothiophenes (DBTs), including 4,6-dimethyldibenzothiophene, the most recalcitrant sulfur compounds in diesel and gasoline, can be completely removed from model gasoline

  13. Efficient Catalytic Ozonation over Reduced Graphene Oxide for p-Hydroxylbenzoic Acid (PHBA) Destruction: Active Site and Mechanism.

    Science.gov (United States)

    Wang, Yuxian; Xie, Yongbing; Sun, Hongqi; Xiao, Jiadong; Cao, Hongbin; Wang, Shaobin

    2016-04-20

    Nanocarbons have been demonstrated as promising environmentally benign catalysts for advanced oxidation processes (AOPs) upgrading metal-based materials. In this study, reduced graphene oxide (rGO) with a low level of structural defects was synthesized via a scalable method for catalytic ozonation of p-hydroxylbenzoic acid (PHBA). Metal-free rGO materials were found to exhibit a superior activity in activating ozone for catalytic oxidation of organic phenolics. The electron-rich carbonyl groups were identified as the active sites for the catalytic reaction. Electron spin resonance (ESR) and radical competition tests revealed that superoxide radical ((•)O2(-)) and singlet oxygen ((1)O2) were the reactive oxygen species (ROS) for PHBA degradation. The intermediates and the degradation pathways were illustrated from mass spectroscopy. It was interesting to observe that addition of NaCl could enhance both ozonation and catalytic ozonation efficiencies and make ·O2(-) as the dominant ROS. Stability of the catalysts was also evaluated by the successive tests. Loss of specific surface area and changes in the surface chemistry were suggested to be responsible for catalyst deactivation. PMID:27007603

  14. Cerium doped red mud catalytic ozonation for bezafibrate degradation in wastewater: Efficiency, intermediates, and toxicity.

    Science.gov (United States)

    Xu, Bingbing; Qi, Fei; Sun, Dezhi; Chen, Zhonglin; Robert, Didier

    2016-03-01

    In this study, the performance of bezafibrate (BZF) degradation and detoxification in the aqueous phase using cerium-modified red mud (RM) catalysts prepared using different cerium sources and synthesis methods were evaluated. Experimental results showed that the surface cerium modification was responsible for the development of the catalytic activity of RM and this was influenced by the cerium source and the synthesis method. Catalyst prepared from cerium (IV) by precipitation was found to show the best catalytic activity in BZF degradation and detoxification. Reactive oxygen species including peroxides, hydroxyl radicals, and super oxide ions were identified in all reactions and we proposed the corresponding catalytic reaction mechanism for each catalyst that prepared from different cerium source and method. This was supported by the intermediates profiles that were generated upon BZF degradation. The surface and the structural properties of cerium-modified RM were characterized in detail by several analytical methods. Two interesting findings were made: (1) the surface texture (specific surface area and mesoporous volume) influenced the catalytic reaction pathway; and (2) Ce(III) species and oxygen vacancies were generated on the surface of the catalyst after cerium modification. This plays an important role in the development of the catalytic activity. PMID:26706928

  15. Efficient Normal-Form Parsing for Combinatory Categorial Grammar

    CERN Document Server

    Eisner, J

    1996-01-01

    Under categorial grammars that have powerful rules like composition, a simple n-word sentence can have exponentially many parses. Generating all parses is inefficient and obscures whatever true semantic ambiguities are in the input. This paper addresses the problem for a fairly general form of Combinatory Categorial Grammar, by means of an efficient, correct, and easy to implement normal-form parsing technique. The parser is proved to find exactly one parse in each semantic equivalence class of allowable parses; that is, spurious ambiguity (as carefully defined) is shown to be both safely and completely eliminated. From no-reply@xxx.lanl.gov Mon Nov 1 11:08 MET 1999 Received: from newmint.cern.ch (newmint.cern.ch [137.138.26.94]) by sundh98.cern.ch (8.8.5/8.8.5) with ESMTP id LAA23068 for ; Mon, 1 Nov 1999 11:08:23 +0100 (MET) Received: from uuu.lanl.gov (root@uuu.lanl.gov [204.121.6.59]) by newmint.cern.ch (8.9.3/8.9.3) with ESMTP id LAA02515 for ; Mon, 1 Nov 1999 11:08:21 +0100 (MET) Received: from xxx.lanl...

  16. Engineering of isoamylase: improvement of protein stability and catalytic efficiency through semi-rational design.

    Science.gov (United States)

    Li, Youran; Zhang, Liang; Ding, Zhongyang; Gu, Zhenghua; Shi, Guiyang

    2016-01-01

    Isoamylase catalyzes the hydrolysis of α-1,6-glycosidic linkages in glycogen, amylopectin and α/β-limit dextrins. A semi-rational design strategy was performed to improve catalytic properties of isoamylase from Bacillus lentus. Three residues in vicinity of the essential residues, Arg505, Asn513, and Gly608, were chosen as the mutation sites and were substituted by Ala, Pro, Glu, and Lys, respectively. Thermal stability of the mutant R505P and acidic stability of the mutant R505E were enhanced. The k cat /K m values of the mutant G608V have been promoted by 49%, and the specific activity increased by 33%. This work provides an effective strategy for improving the catalytic activity and stability of isoamylase, and the results obtained here may be useful for the improvement of catalytic properties of other α/β barrel enzymes.

  17. Efficient free-form surface representation with application in orthodontics

    Science.gov (United States)

    Yamany, Sameh M.; El-Bialy, Ahmed M.

    1999-03-01

    Orthodontics is the branch of dentistry concerned with the study of growth of the craniofacial complex. The detection and correction of malocclusion and other dental abnormalities is one of the most important and critical phases of orthodontic diagnosis. This paper introduces a system that can assist in automatic orthodontics diagnosis. The system can be used to classify skeletal and dental malocclusion from a limited number of measurements. This system is not intended to deal with several cases but is aimed at cases more likely to be encountered in epidemiological studies. Prior to the measurement of the orthodontics parameters, the position of the teeth in the jaw model must be detected. A new free-form surface representation is adopted for the efficient and accurate segmentation and separation of teeth from a scanned jaw model. THe new representation encodes the curvature and surface normal information into a 2D image. Image segmentation tools are then sued to extract structures of high/low curvature. By iteratively removing these structures, individual teeth surfaces are obtained.

  18. On the functional form of an efficiency index

    DEFF Research Database (Denmark)

    Hougaard, Jens Leth; Keiding, Hans

    1998-01-01

    An input efficiency index gives a numeric assessment of the degree to which a given input combination falls short of being efficient in producing a fixed amount of output. This paper presents a system of axioms which characterise a certain family of efficiency indices containing the well-known Fa......An input efficiency index gives a numeric assessment of the degree to which a given input combination falls short of being efficient in producing a fixed amount of output. This paper presents a system of axioms which characterise a certain family of efficiency indices containing the well...

  19. β-Alanine-DBU" A Highly Efficient Catalytic System forKnoevenageI-Doebner Reaction under Mild Conditionsβ-Alanine-DBU" A Highly Efficient Catalytic System forKnoevenageI-Doebner Reaction under Mild Conditions

    Institute of Scientific and Technical Information of China (English)

    祝令建; 雷宁; 缪震元; 盛春泉; 庄春林; 姚建忠; 张万年

    2012-01-01

    A mild and efficient Knoevenagel-Doebner reaction from malonic acid and a wide range of aldehydes was catalyzed by a catalytic system consisting offlalanine and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), affording the corresponding (E)-a,fl-unsaturated carboxylic acids in good to excellent yields and with high stereoselectivity. The advantage of the method is that the reaction could proceed smoothly at ambient temperature so that it can tolerate a variety of functional groups and avoid unnecessary side reactions.

  20. Design and Synthesis of Chiral Zn2+ Complexes Mimicking Natural Aldolases for Catalytic C–C Bond Forming Reactions in Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Susumu Itoh

    2014-01-01

    Full Text Available Extending carbon frameworks via a series of C–C bond forming reactions is essential for the synthesis of natural products, pharmaceutically active compounds, active agrochemical ingredients, and a variety of functional materials. The application of stereoselective C–C bond forming reactions to the one-pot synthesis of biorelevant compounds is now emerging as a challenging and powerful strategy for improving the efficiency of a chemical reaction, in which some of the reactants are subjected to successive chemical reactions in just one reactor. However, organic reactions are generally conducted in organic solvents, as many organic molecules, reagents, and intermediates are not stable or soluble in water. In contrast, enzymatic reactions in living systems proceed in aqueous solvents, as most of enzymes generally function only within a narrow range of temperature and pH and are not so stable in less polar organic environments, which makes it difficult to conduct chemoenzymatic reactions in organic solvents. In this review, we describe the design and synthesis of chiral metal complexes with Zn2+ ions as a catalytic factor that mimic aldolases in stereoselective C–C bond forming reactions, especially for enantioselective aldol reactions. Their application to chemoenzymatic reactions in aqueous solution is also presented.

  1. Upgrading of bio-oil to boiler fuel by catalytic hydrotreatment and esterification in an efficient process

    International Nuclear Information System (INIS)

    Bio-oil can't be directly used as fuel due to its deteriorate properties. Here, an efficient catalytic upgrading process for the bio-oil, including esterification, hydrogenation, hydrodeoxygenation and depolymerization, is proposed with multifunctional catalyst Ni/SiO2–ZrO2 and biomass-derived solvent ethanol. Results showed that esters, alcohols, phenolics, and cyclo-ketones were the main components in the upgraded bio-oil while aldehydes were removed completely via catalytic hydrogenation and acids were removed by catalytic esterification with supercritical ethanol. The pH value of upgraded bio-oil rose drastically from 2.38 to 5.24, and the high heating value increased to 24.4 MJ kg−1. Comparison characterization on the upgraded and crude bio-oil using FT-IR, GPC (Gel permeation chromatography) and 13C NMR (Nuclear Magnetic Resonance) demonstrated that lignin-derived oligomers contained in crude bio-oil were further depolymerized over Ni/SiO2–ZrO2 catalyst. The improved properties suggest that the upgraded bio-oil is more suitable to be used as boiler fuel. Furthermore, the loss of carbon is negligible because formation of coke is suppressed during the upgrading process. - Highlights: • Acid can be converted via catalytic esterification in supercritical ethanol. • Aldehydes can be removed completely during the upgrading process. • Lignin-derived oligomers were further depolymerized during the upgrading process. • Formation of coke is effectively inhibited during the upgrading process

  2. An efficient heterogeneous procedure for the catalytic acetalization and ketalization at room temperature under solvent-free condition

    Institute of Scientific and Technical Information of China (English)

    GAO Shan; LIANG XueZheng; CHENG WenPing; WANG Wen Juan; YANG JianGuo

    2008-01-01

    A novel carbon-based strong acid catalyst, methylnaphthalenesulfonic acid-formaldehyde condensate, has been synthesized successfully. The catalytic activity for acetalization and ketalization at room tem-perature under solvent-free condition was investigated. The results showed that the novel catalyst was very efficient for the reaction. Also the novel heterogeneous catalyst owned the advantages of high activity, wide applicability, strikingly simple work-up procedure, non-pollution, stability and reusability, which made the catalyst hold great potential for the "green process".

  3. Is the Mongolian Equity Market Efficient? Empirical Evidence from Tests of Weak-Form Efficiency

    OpenAIRE

    Lim Kai Jie, Shawn; Chadha, Pavneet; Lau, Joshua; Potdar, Nishad

    2012-01-01

    This paper investigates the empirical validity of the weak-form of the Efficient Market Hypothesis in the Mongolian equity market over Jan 1999 to Jul 2012. We examine the characteristics of the market by testing the fit of returns to a normal distribution using the Jarque-Bera Test, and find strong evidence against normality. The data also exhibits positive skewness and a high level of excess kurtosis. Next, we test for the presence of autocorrelation using the Ljung-Box Q Test and the non-p...

  4. Aroylhydrazone Cu(II) complexes in keto form: structural characterization and catalytic cctivity towards cyclohexane oxidation

    OpenAIRE

    Manas Sutradhar; Elisabete C. B. A. Alegria; Guedes da Silva, M. Fátima C.; Martins, Luísa M. D. R. S.; Pombeiro, Armando J. L.

    2016-01-01

    The reaction of the Schiff base (3,5-di-tert-butyl-2-hydroxybenzylidene)-2-hydroxybenzohydrazide (H3L) with a copper(II) salt of a base of a strong acid, i.e., nitrate, chloride or sulphate, yielded the mononuclear complexes [Cu(H2L)(NO3)(H2O)] (1), [Cu(H2L)Cl]center dot 2MeOH (2) and the binuclear complex [{Cu(H2L)}(2)(mu-SO4)]center dot 2MeOH (3), respectively, with H2L- in the keto form. Compounds 1-3 were characterized by elemental analysis, Infrared (IR) spectroscopy, Electrospray Ionisa...

  5. Lysosome-controlled efficient ROS overproduction against cancer cells with a high pH-responsive catalytic nanosystem

    Science.gov (United States)

    Fu, Jingke; Shao, Yiran; Wang, Liyao; Zhu, Yingchun

    2015-04-01

    Excess reactive oxygen species (ROS) have been proved to damage cancer cells efficiently. ROS overproduction is thus greatly desirable for cancer therapy. To date, ROS production is generally uncontrollable and outside cells, which always bring severe side-effects in the vasculature. Since most ROS share a very short half-life and primarily react close to their site of formation, it would be more efficient if excess ROS are controllably produced inside cancer cells. Herein, we report an efficient lysosome-controlled ROS overproduction via a pH-responsive catalytic nanosystem (FeOx-MSNs), which catalyze the decomposition of H2O2 to produce considerable ROS selectively inside the acidic lysosomes (pH 5.0) of cancer cells. After a further incorporation of ROS-sensitive TMB into the nanosystem (FeOx-MSNs-TMB), both a distinct cell labeling and an efficient death of breast carcinoma cells are obtained. This lysosome-controlled efficient ROS overproduction suggests promising applications in cancer treatments.Excess reactive oxygen species (ROS) have been proved to damage cancer cells efficiently. ROS overproduction is thus greatly desirable for cancer therapy. To date, ROS production is generally uncontrollable and outside cells, which always bring severe side-effects in the vasculature. Since most ROS share a very short half-life and primarily react close to their site of formation, it would be more efficient if excess ROS are controllably produced inside cancer cells. Herein, we report an efficient lysosome-controlled ROS overproduction via a pH-responsive catalytic nanosystem (FeOx-MSNs), which catalyze the decomposition of H2O2 to produce considerable ROS selectively inside the acidic lysosomes (pH 5.0) of cancer cells. After a further incorporation of ROS-sensitive TMB into the nanosystem (FeOx-MSNs-TMB), both a distinct cell labeling and an efficient death of breast carcinoma cells are obtained. This lysosome-controlled efficient ROS overproduction suggests

  6. Kemp elimination in membrane mimetic reaction media : Probing catalytic properties of catanionic vesicles formed from double-tailed amphiphiles

    NARCIS (Netherlands)

    Klijn, JE; Engberts, JBFN

    2003-01-01

    The rate-determining deprotonation of 5-nitrobenzisoxazole (Kemp elimination) by hydroxide is efficiently catalyzed by vesicles formed from dimethyldioctadecylammonium chloride (C18C18+). Gradual addition of sodium didecyl phosphate (C10C10-) leads to the formation of catanionic vesicles, which were

  7. Modeling and simulation of hydrodemetallation and hydrodesulfurization processes with transient catalytic efficiency

    Directory of Open Access Journals (Sweden)

    E.M. Matos

    2000-06-01

    Full Text Available A model is presented for the description of the concentration behavior of organometallic and sulfurated compounds in hydrodemetallation and hydrodesulfurization catalytic processes, where catalyst effectiveness decreases with time. Due to the complexity of the mixture, an approach based on pseudocomponents was adopted. The system is modeled as an isothermal tubular reactor with axial dispersion, where the gas phase (hydrogen in excess flows upward concurrently with the liquid phase (heavy oil while the solid phase (catalyst stays inside the reactor in an expanded (confined bed regime. The catalyst particles are very small and are assumed to be uniformly distributed in the reactor. The heavy oil fractions contain organometallics and sulfurated compounds, from which the metals and sulfur are to be removed, the metals as deposits in the catalyst pores and the sulfur as gas products. Simulations were carried out where the concentration profile inside the reactor was calculated for several residence times.

  8. Invoking Direct Exciton-Plasmon Interactions by Catalytic Ag Deposition on Au Nanoparticles: Photoelectrochemical Bioanalysis with High Efficiency.

    Science.gov (United States)

    Ma, Zheng-Yuan; Xu, Fei; Qin, Yu; Zhao, Wei-Wei; Xu, Jing-Juan; Chen, Hong-Yuan

    2016-04-19

    In this work, direct exciton-plasmon interactions (EPI) between CdS quantum dots (QDs) and Ag nanoparticles (NPs) were invoked ingeniously by catalytic Ag deposition on Au NPs for the stimulation of high efficient damping effect toward the excitonic responses in CdS QDs, on the basis of which a novel photoelectrochemical (PEC) bioanalytical format was achieved for sensitive microRNA detection. Specifically, upon the configurational change from the hairpin probe DNA to the "Y"-shaped ternary conjugate consisting of the original probe DNA, assistant DNA, and the target microRNA, the alkaline phosphatase (ALP) catalytic chemistry would then trigger the transition of the interparticle interplay from the CdS QDs-Au NPs to the CdS QDs-Ag NPs systems for the microRNA detection due to the dependence of the photocurrent quenching on the target concentration. This work not only provided a unique method for EPI generation among the PEC nanosystems but also offered a versatile and general protocol for future PEC bioanalysis development. PMID:27023112

  9. Effect of process parameters and injector position on the efficiency of NOx reduction by selective non catalytic reduction technique

    International Nuclear Information System (INIS)

    An experimental investigation has been performed to study the effect of atomizer pressure dilution of the reducing reagent and the injector position on the efficiency or the NOx reduction by a selective non-catalytic reduction technique using urea as a reducing agent. Experiments were performed with a flow reactor in which flue gas was generated by the combustion of methane in air at stoichiometric amount of oxygen and the desired levels of initial NOx (400-450 ppm) were achieved by doping the flame with ammonia. The work was directed to investigate the effect of atomizer pressure, dilution of urea reagent and the injector position. The atomizer pressure was varied from 1 to 3bar and 20-25% increase in efficiency was observed by decreasing the pressure. Effect of dilution of urea solution was investigated by varying the strength of the solution from the 8 to 32% and 40-45% increase in the efficiency was observed. Effects of injector position was investigated by injecting the urea solution both in co current and counter current direction of the flue gases and 20-25% increase in the efficiency was observed in counter current direction. (author)

  10. Precipitation and calcination synthesis methods forming nano-sized platinum catalytic particles for methanol and hydrogen oxidation

    Science.gov (United States)

    Naidoo, S.; Naidoo, Q.; Musil, E.; Linkov, V.; Vaivars, G.

    2013-03-01

    Under varying experimental conditions of calcination and precipitation reactions, different particle sizes and levels of platinum on carbon supported (Pt/C) catalysts were obtained. Rapid precipitation following a chemical reaction ensured formation of nano-sized catalytic particles using super-saturated concentrations under controlled conditions was a significant contribution in understanding the synthesis process and how it relates to an increased number of catalytic reaction sites ultimately providing superior electrochemical (EC) activity. These conditions influenced nucleation and growth rates of the catalytic particles. The super-saturation concentrations of the reactants in the reaction vessel played a direct role in producing the desired morphology of the crystallites.

  11. Highly Efficient Small Form Factor LED Retrofit Lamp

    Energy Technology Data Exchange (ETDEWEB)

    Steven Allen; Fred Palmer; Ming Li

    2011-09-11

    This report summarizes work to develop a high efficiency LED-based MR16 lamp downlight at OSRAM SYLVANIA under US Department of Energy contract DE-EE0000611. A new multichip LED package, electronic driver, and reflector optic were developed for these lamps. At steady-state, the lamp luminous flux was 409 lumens (lm), luminous efficacy of 87 lumens per watt (LPW), CRI (Ra) of 87, and R9 of 85 at a correlated color temperature (CCT) of 3285K. The LED alone achieved 120 lumens per watt efficacy and 600 lumen flux output at 25 C. The driver had 90% electrical conversion efficiency while maintaining excellent power quality with power factor >0.90 at a power of only 5 watts. Compared to similar existing MR16 lamps using LED sources, these lamps had much higher efficacy and color quality. The objective of this work was to demonstrate a LED-based MR16 retrofit lamp for replacement of 35W halogen MR16 lamps having (1) luminous flux of 500 lumens, (2) luminous efficacy of 100 lumens per watt, (3) beam angle less than 40{sup o} and center beam candlepower of at least 1000 candelas, and (4) excellent color quality.

  12. ORGANIZATIONAL FORM AND EFFICIENCY: THE COEXISTENCE OF FAMILY TAKAFUL AND LIFE INSURANCE IN MALAYSIA

    OpenAIRE

    Norashikin Ismail Author_Email:; Prof. Dr. Datuk Syed Othman Alhabshi; Prof Obiyathulla Bacha

    2011-01-01

    After 25 years in operation, it is time that takaful industry is evaluated in terms of its performance. One of the issues that has impact on efficiency is organization form. There have been two conflicting opinions on this issue. Eling & Luhnen (2010) opined that mutual form is efficient than stock form but Brockett (2005) concluded the opposite. This paper provides an empirical study on the relationship between efficiency and organizational structure for takaful operators in Malaysian dual f...

  13. In situ formed catalytically active ruthenium nanocatalyst in room temperature dehydrogenation/dehydrocoupling of ammonia-borane from Ru(cod)(cot) precatalyst.

    Science.gov (United States)

    Zahmakiran, Mehmet; Ayvalı, Tuğçe; Philippot, Karine

    2012-03-20

    The development of simply prepared and effective catalytic materials for dehydrocoupling/dehydrogenation of ammonia-borane (AB; NH(3)BH(3)) under mild conditions remains a challenge in the field of hydrogen economy and material science. Reported herein is the discovery of in situ generated ruthenium nanocatalyst as a new catalytic system for this important reaction. They are formed in situ during the dehydrogenation of AB in THF at 25 °C in the absence of any stabilizing agent starting with homogeneous Ru(cod)(cot) precatalyst (cod = 1,5-η(2)-cyclooctadiene; cot = 1,3,5-η(3)-cyclooctatriene). The preliminary characterization of the reaction solutions and the products was done by using ICP-OES, ATR-IR, TEM, XPS, ZC-TEM, GC, EA, and (11)B, (15)N, and (1)H NMR, which reveal that ruthenium nanocatalyst is generated in situ during the dehydrogenation of AB from homogeneous Ru(cod)(cot) precatalyst and B-N polymers formed at the initial stage of the catalytic reaction take part in the stabilization of this ruthenium nanocatalyst. Moreover, following the recently updated approach (Bayram, E.; et al. J. Am. Chem. Soc.2011, 133, 18889) by performing Hg(0), CS(2) poisoning experiments, nanofiltration, time-dependent TEM analyses, and kinetic investigation of active catalyst formation to distinguish single metal or in the present case subnanometer Ru(n) cluster-based catalysis from polymetallic Ru(0)(n) nanoparticle catalysis reveals that in situ formed Ru(n) clusters (not Ru(0)(n) nanoparticles) are kinetically dominant catalytically active species in our catalytic system. The resulting ruthenium catalyst provides 120 total turnovers over 5 h with an initial turnover frequency (TOF) value of 35 h(-1) at room temperature with the generation of more than 1.0 equiv H(2) at the complete conversion of AB to polyaminoborane (PAB; [NH(2)BH(2)](n)) and polyborazylene (PB; [NHBH](n)) units. PMID:22356554

  14. A Novel and Efficient Catalytic System for Aerobic Oxidative Coupling of 2-Naphthol Derivatives

    Institute of Scientific and Technical Information of China (English)

    Li CHEN; Jing Bo LAN; Zhi Hua MAO; Xiao Qi YU; Ru Gang XIE

    2004-01-01

    The paper reported a novel and efficient aerobic oxidative coupling reaction of 2-naphthol derivatives catalyzed by CuCu (I or II)N-alkylimidazole complexes in excellent yields.The crystal structure of CuCu (II)N-methylimidazole complex to be determined by X-Ray.

  15. High Efficiency Solar-based Catalytic Structure for CO{sub 2} Reforming

    Energy Technology Data Exchange (ETDEWEB)

    Menkara, Hisham

    2013-09-30

    Throughout this project, we developed and optimized various photocatalyst structures for CO{sub 2} reforming into hydrocarbon fuels and various commodity chemical products. We also built several closed-loop and continuous fixed-bed photocatalytic reactor system prototypes for a larger-scale demonstration of CO{sub 2} reforming into hydrocarbons, mainly methane and formic acid. The results achieved have indicated that with each type of reactor and structure, high reforming yields can be obtained by refining the structural and operational conditions of the reactor, as well as by using various sacrificial agents (hole scavengers). We have also demonstrated, for the first time, that an aqueous solution containing acid whey (a common bio waste) is a highly effective hole scavenger for a solar-based photocatalytic reactor system and can help reform CO{sub 2} into several products at once. The optimization tasks performed throughout the project have resulted in efficiency increase in our conventional reactors from an initial 0.02% to about 0.25%, which is 10X higher than our original project goal. When acid whey was used as a sacrificial agent, the achieved energy efficiency for formic acid alone was ~0.4%, which is 16X that of our original project goal and higher than anything ever reported for a solar-based photocatalytic reactor. Therefore, by carefully selecting sacrificial agents, it should be possible to reach energy efficiency in the range of the photosynthetic efficiency of typical crop and biofuel plants (1-3%).

  16. Is the Swedish stock market efficient? : Testing the weak form of efficient market hypothesis

    OpenAIRE

    Lindvall, Joacim; Rangert, Fredrik

    2012-01-01

    This paper examines the efficiency of the Swedish stock market, by testing if it is possible to create an excess return by the use of technical trading rules. According to the efficient market hypothesis and the random walk theory, in an efficient market it is not possible to predict the future stock prices by analyzing historical stock prices. The profitability of tech-nical analysis and technical trading rules has been researched and debated extensively, but economists have yet to reach a c...

  17. Molybdatophosphoric acid as an efficient catalyst for the catalytic and chemoselective oxidation of sulfides to sulfoxides using urea hydrogen peroxide as a commercially available oxidant

    Directory of Open Access Journals (Sweden)

    ALIREZA HASANINEJAD

    2010-03-01

    Full Text Available An efficient procedure for the chemoselective oxidation of alkyl (aryl sulfides to the corresponding sulfoxides using urea hydrogen peroxide (UHP in the presence of a catalytic amount of molybdatophosphoric acid at room temperature is described. The advantages of described method are: generality, high yield and chemoselectivity, short reaction time, low cost and compliment with green chemistry protocols.

  18. Experimental demonstration of the reverse flow catalytic membrane reactor concept for energy efficient syngas production. Part 1: Influence of operating conditions

    NARCIS (Netherlands)

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

    2007-01-01

    In this contribution the technical feasibility of the reverse flow catalytic membrane reactor (RFCMR) concept with porous membranes for energy efficient syngas production is investigated. In earlier work an experimental proof of principle was already provided [Smit, J., Bekink, G.J., van Sint Annala

  19. Relative Catalytic Efficiency of ldhL- and ldhD-Encoded Products Is Crucial for Optical Purity of Lactic Acid Produced by Lactobacillus Strains

    OpenAIRE

    Zheng, Zhaojuan; Sheng, Binbin; Ma, Cuiqing; Zhang, Haiwei; Gao, Chao; Su, Fei; Xu, Ping

    2012-01-01

    NAD-dependent l- and d-lactate dehydrogenases coexist in Lactobacillus genomes and may convert pyruvic acid into l-lactic acid and d-lactic acid, respectively. Our findings suggest that the relative catalytic efficiencies of ldhL- and ldhD-encoded products are crucial for the optical purity of lactic acid produced by Lactobacillus strains.

  20. Modeling and Re-Engineering of Azotobacter vinelandii Alginate Lyase to Enhance Its Catalytic Efficiency for Accelerating Biofilm Degradation.

    Directory of Open Access Journals (Sweden)

    Chul Ho Jang

    Full Text Available Alginate is known to prevent elimination of Pseudomonas aeruginosa biofilms. Alginate lyase (AlgL might therefore facilitate treatment of Pseudomonas aeruginosa-infected cystic fibrosis patients. However, the catalytic activity of wild-type AlgL is not sufficiently high. Therefore, molecular modeling and site-directed mutagenesis of AlgL might assist in enzyme engineering for therapeutic development. AlgL, isolated from Azotobacter vinelandii, catalyzes depolymerization of alginate via a β-elimination reaction. AlgL was modeled based on the crystal structure template of Sphingomonas AlgL species A1-III. Based on this computational analysis, AlgL was subjected to site-directed mutagenesis to improve its catalytic activity. The kcat/Km of the K194E mutant showed a nearly 5-fold increase against the acetylated alginate substrate, as compared to the wild-type. Double and triple mutants (K194E/K245D, K245D/K319A, K194E/K245D/E312D, and K194E/K245D/K319A were also prepared. The most potent mutant was observed to be K194E/K245D/K319A, which has a 10-fold improved kcat value (against acetylated alginate compared to the wild-type enzyme. The antibiofilm effect of both AlgL forms was identified in combination with piperacillin/tazobactam (PT and the disruption effect was significantly higher in mutant AlgL combined with PT than wild-type AlgL. However, for both the wild-type and K194E/K245D/K319A mutant, the use of the AlgL enzyme alone did not show significant antibiofilm effect.

  1. Modeling and Re-Engineering of Azotobacter vinelandii Alginate Lyase to Enhance Its Catalytic Efficiency for Accelerating Biofilm Degradation

    Science.gov (United States)

    Jang, Chul Ho; Piao, Yu Lan; Huang, Xiaoqin; Yoon, Eun Jeong; Park, So Hee; Lee, Kyoung; Zhan, Chang-Guo; Cho, Hoon

    2016-01-01

    Alginate is known to prevent elimination of Pseudomonas aeruginosa biofilms. Alginate lyase (AlgL) might therefore facilitate treatment of Pseudomonas aeruginosa-infected cystic fibrosis patients. However, the catalytic activity of wild-type AlgL is not sufficiently high. Therefore, molecular modeling and site-directed mutagenesis of AlgL might assist in enzyme engineering for therapeutic development. AlgL, isolated from Azotobacter vinelandii, catalyzes depolymerization of alginate via a β-elimination reaction. AlgL was modeled based on the crystal structure template of Sphingomonas AlgL species A1-III. Based on this computational analysis, AlgL was subjected to site-directed mutagenesis to improve its catalytic activity. The kcat/Km of the K194E mutant showed a nearly 5-fold increase against the acetylated alginate substrate, as compared to the wild-type. Double and triple mutants (K194E/K245D, K245D/K319A, K194E/K245D/E312D, and K194E/K245D/K319A) were also prepared. The most potent mutant was observed to be K194E/K245D/K319A, which has a 10-fold improved kcat value (against acetylated alginate) compared to the wild-type enzyme. The antibiofilm effect of both AlgL forms was identified in combination with piperacillin/tazobactam (PT) and the disruption effect was significantly higher in mutant AlgL combined with PT than wild-type AlgL. However, for both the wild-type and K194E/K245D/K319A mutant, the use of the AlgL enzyme alone did not show significant antibiofilm effect. PMID:27253324

  2. Focus-on-Forms, Focus-on-Form, and Their Efficiency in Vocabulary Teaching and Learning

    Institute of Scientific and Technical Information of China (English)

    阿娜

    2014-01-01

    Vocabulary is generally recognized as most critical in foreign language learning. Students who get up early in the morning to read out loud word lists have been a popular and encouraging spot on campus. Although there is abundant research about vocabulary.This paper will review the development of FonF and FonFS in the field of ESL, and their relationship with vocabulary learning, exploring the possibilities of comparing FonF and FonFS in terms of their efficiency in vocabulary teaching and learning.

  3. Accuracy-rate tradeoffs: how do enzymes meet demands of selectivity and catalytic efficiency?

    Science.gov (United States)

    Tawfik, Dan S

    2014-08-01

    I discuss some physico-chemical and evolutionary aspects of enzyme accuracy (selectivity, specificity) and speed (turnover rate, processivity). Accuracy can be a beneficial side-product of active-sites being refined to proficiently convert a given substrate into one product. However, exclusion of undesirable, non-cognate substrates is also an explicitly evolved trait that may come with a cost. I define two schematic mechanisms. Ground-state discrimination applies to enzymes where selectivity is achieved primarily at the level of substrate binding. Exemplified by DNA methyltransferases and the ribosome, ground-state discrimination imposes strong accuracy-rate tradeoffs. Alternatively, transition-state discrimination, applies to relatively small substrates where substrate binding and chemistry are efficiently coupled, and evokes weaker tradeoffs. Overall, the mechanistic, structural and evolutionary basis of enzymatic accuracy-rate tradeoffs merits deeper understanding.

  4. Efficient catalytic system for the conversion of fructose into 5-ethoxymethylfurfural.

    Science.gov (United States)

    Wang, Hongliang; Deng, Tiansheng; Wang, Yingxiong; Qi, Yongqin; Hou, Xianglin; Zhu, Yulei

    2013-05-01

    DMSO can improve the selectivity of 5-hydroxymethylfurfural (HMF) in the conversion of carbohydrates. However, one of the bottlenecks in its application is product separation. Thus a one-pot synthesis of 5-ethoxymethylfurfural (EMF) rather than HMF from fructose in ethanol-DMSO was investigated. Phosphotungstic acid was used as an effective catalyst. The yield of EMF can be reached as high as 64% in the mixed solvent system of DMSO and ethanol within 130 min at 140 °C. Ethyl levulinate (LAE) was detected as the main by-product, the yield of which increased with the reaction time, temperature and the amount of catalyst. In addition, the existence of water could significantly reduce the yield of EMF and increased the yield of LAE. Most importantly, it was discovered that EMF could be much more efficiently extracted from the reaction solvent system by some organic solvents than HMF. PMID:23567707

  5. In-situ generated H2O2 induced efficient visible light photo-electrochemical catalytic oxidation of PCP-Na with TiO2

    International Nuclear Information System (INIS)

    Graphical abstract: We demonstrate a novel PEC system where the cathodic in-situ generated H2O2 interacts with TiO2 particles to form interfacial TiIV−OOH species which endow TiO2 with visible light photocatalytic activity for efficient PCP-Na degradation for the first time. - Highlights: • We demonstrate a novel visible light driven PEC system for efficient PCP-Na degradation. • The in-situ generated H2O2 reacts with TiO2 suspensions to form interfacial TiIV−OOH species. • TiIV−OOH species endow TiO2 with visible light photocatalytic activity. • ·O2− and ·OH are responsible for the dechlorination and mineralization of PCP-Na, respectively. - Abstract: In this study, we developed a novel photo-electrochemical catalytic oxidation wastewater treatment system by interacting the cathodic in-situ generated H2O2 with TiO2 suspension to form interfacial ≡TiIV−OOH species, which endowed the PEC system with superior efficiency for degrading sodium pentachlorophenate (PCP-Na) under visible light irradiation at neutral pH. The apparent PCP-Na degradation rate constant of the PEC system was more than 10 times that of the electrochemical oxidation counterpart. In the PEC system, the interfacial ≡TiIV−OOH species injected electrons to the conduction band of TiO2 to initiate the activation of O2 and the in-situ generated H2O2 adsorbed on the surface of TiO2, lead to producing reactive oxygen species of superoxide anions and hydroxyl radicals, which were responsible for the dechlorination and mineralization of PCP-Na during the PEC process, respectively. The dosage of TiO2 catalyst and the current intensity applied on PCP-Na degradation were optimized. This study develops a high efficient PEC oxidation system for wastewater treatment and provides new insight into the role of cathodic in-situ generated H2O2 on PEC oxidation of PCP-Na with TiO2 under visible light irradiation

  6. Indium triflate in 1-isobutyl-3-methylimidazolium dihydrogenphosphate: an efficient and green catalytic system for Friedel-Crafts acylation

    DEFF Research Database (Denmark)

    Tran, Phuong Hoang; Hoang, Huy Manh; Chau, Duy-Khiem Nguyen;

    2015-01-01

    Indium triflate in the ionic liquid, 1-isobutyl-3-methylimidazolium dihydrogen phosphate ([i-BMIM]H2PO4), was found to show enhanced catalytic activity in the Friedel–Crafts acylation of various aromatic compounds with acid anhydrides. The catalytic system was easily recovered and reused without ...

  7. Enhanced Electrochemical Catalytic Efficiencies of Electrochemically Deposited Platinum Nanocubes as a Counter Electrode for Dye-Sensitized Solar Cells

    Science.gov (United States)

    Wei, Yu-Hsuan; Tsai, Ming-Chi; Ma, Chen-Chi M.; Wu, Hsuan-Chung; Tseng, Fan-Gang; Tsai, Chuen-Horng; Hsieh, Chien-Kuo

    2015-12-01

    Platinum nanocubes (PtNCs) were deposited onto a fluorine-doped tin oxide glass by electrochemical deposition (ECD) method and utilized as a counter electrode (CE) for dye-sensitized solar cells (DSSCs). In this study, we controlled the growth of the crystalline plane to synthesize the single-crystal PtNCs at room temperature. The morphologies and crystalline nanostructure of the ECD PtNCs were examined by field emission scanning electron microscopy and high-resolution transmission electron microscopy. The surface roughness of the ECD PtNCs was examined by atomic force microscopy. The electrochemical properties of the ECD PtNCs were analyzed by cyclic voltammetry, Tafel polarization, and electrochemical impedance spectra. The Pt loading was examined by inductively coupled plasma mass spectrometry. The DSSCs were assembled via an N719 dye-sensitized titanium dioxide working electrode, an iodine-based electrolyte, and a CE. The photoelectric conversion efficiency (PCE) of the DSSCs with the ECD PtNC CE was examined under the illumination of AM 1.5 (100 mWcm-2). The PtNCs in this study presented a single-crystal nanostructure that can raise the electron mobility to let up the charge-transfer impedance and promote the charge-transfer rate. In this work, the electrocatalytic mass activity (MA) of the Pt film and PtNCs was 1.508 and 4.088 mAmg-1, respectively, and the MA of PtNCs was 2.71 times than that of the Pt film. The DSSCs with the pulse-ECD PtNC CE showed a PCE of 6.48 %, which is higher than the cell using the conventional Pt film CE (a PCE of 6.18 %). In contrast to the conventional Pt film CE which is fabricated by electron beam evaporation method, our pulse-ECD PtNCs maximized the Pt catalytic properties as a CE in DSSCs. The results demonstrated that the PtNCs played a good catalyst for iodide/triiodide redox couple reactions in the DSSCs and provided a potential strategy for electrochemical catalytic applications.

  8. Highly efficient degradation of 4-nitrophenol over the catalyst of Mn2O3/AC by microwave catalytic oxidation degradation method.

    Science.gov (United States)

    Yin, Cheng; Cai, Jinjun; Gao, Lingfei; Yin, Jingya; Zhou, Jicheng

    2016-03-15

    A new microwave catalytic oxidation process based on two kinds of catalysts, the commercially available activated carbon (AC) and Mn2O3 nanoparticle modified AC (Mn2O3/AC), was reported for the degradation of 4-nitrophenol (4-NP) without adding any oxidant. Effects of microwave power, catalyst dosage, irradiation time, and initial concentration for the degradation efficiency were studied. Results indicated that catalyst of Mn2O3/AC showed much higher catalytic activity than pure AC and Mn2O3 particles. Significantly, 4-NP degradation efficiency reached 99.6%, corresponding to 93.5% TOC removal under optimal conditions with microwave power of 400W, Mn2O3/AC dosage of 2g, reaction time of 5min, and initial concentration of 100mg/L. Hydroxyl radicals (OH) generated during catalytic reaction is the main oxidant, and O2 can not effectively improve removal rate. We proposed the microwave 'photoelectric effect' to interpret the generation of OH in view that microwave irradiation can directly excite the catalyst to produce electron-hole pairs and then transform H2O into OH on the surface of catalyst in solution. The obtained kinetic equation for microwave catalytic oxidation degradation of 4-NP was in line with pseudo-first-order kinetic model, that is, apparent rate constant increased as microwave power density increase.

  9. Investigation on the catalytic effects of AAEM during steam gasification and the resultant char reactivity in oxygen using Shengli lignite at different forms

    Institute of Scientific and Technical Information of China (English)

    Jianxin Mi; Ningbo Wang; Mingfeng Wang; Pengju Huo; Dan Liu

    2015-01-01

    The purpose of this study is to investigate the catalytic effects of alkali and alkaline earth metallic species (AAEM) on char conversion during the gasification in steam and the changes in ex-situ char reactivity in oxygen after the gasification in steam using different forms (i.e. H-form, Na-form) of Shengli brown coal. The surface area, AAEM concentration and carbon crystallite of chars were obtained to understand the change in char reactivity. It was found that not only Na concentration and carbon structure were the main factors governing the char reactivity in the atmosphere of steam and oxygen, but also they interacted each other. The presence of Na could facilitate the formation of disordering carbon structure in char, and the amorphous carbon structure would in turn affect the distribution of Na and thus its catalytic performance. The surface area and pore volume had very little relationship with the char’s reactivity. Addi-tionally, the morphology of chars from different forms of coals were observed using scanning electron microscope (SEM).

  10. Condition in ci engine’s exhaust pipe in light of application nox sensor to determine of catalytic converter efficiency

    OpenAIRE

    Rychter, M.

    2010-01-01

    The development of a catalytic converter required an analysis of selected physical parameters of the supports. This resulted from the necessity to assume given parameters of the supports applied in the tests in exhaust gas environment in the CI engines. An analysis of ionic conductors which constitute the basic solution in voltage sensors providing signals through NOx electrocatalysis. The aim of this paper is to determine the basis for the monitoring of catalytic converters in compression ig...

  11. Improvement of the thermostability and catalytic efficiency of a highly active β-glucanase from Talaromyces leycettanus JCM12802 by optimizing residual charge–charge interactions

    OpenAIRE

    You, Shuai; Tu, Tao; Zhang, Lujia; Wang, Yuan; Huang, Huoqing; Ma, Rui; Shi, Pengjun; Bai, Yingguo; Su, Xiaoyun; Lin, Zhemin; Luo, Huiying; Yao, Bin

    2016-01-01

    Background β-Glucanase is one of the most extensively used biocatalysts in biofuel, food and animal feed industries. However, the poor thermostability and low catalytic efficiency of most reported β-glucanases limit their applications. Currently, two strategies are used to overcome these bottlenecks, i.e., mining for novel enzymes from extremophiles and engineering existing enzymes. Results A novel endo-β-1,3-1,4-glucanase of GH16 (Tlglu16A) from the thermophilic fungus Talaromyces leycettanu...

  12. THE FORM OF THE COOKING VESSEL AND THE ENERGETIC EFFICIENCY OF COOKING

    Directory of Open Access Journals (Sweden)

    PAUL KRÄMER

    2009-09-01

    Full Text Available The present paper examines the contribution of the form of the cooking vessel to the heat transfer efficiency of the stove/pot system. A rounded (convex pot bottom increases the surface available for heat transfer and, hence, heat transfer efficiency. We suggest that combustion-efficient stoves combined with rounded-bottom vessels compare favourably to the same stoves in combination with flat-bottom stoves. Clay pots with a rounded bottom correspond to African traditions. Nowadays metal pots with rounded bottoms are locally produced in some areas. Implications of pot forms for the outcome of Water Boiling Tests are also discussed.

  13. Catalytic combustor for hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Mercea, J.; Grecu, E.; Fodor, T.; Kreibik, S.

    1982-01-01

    The performance of catalytic combustors for hydrogen using platinum-supported catalysts is described. Catalytic plates of different sizes were constructed using fibrous and ceramic supports. The temperature distribution as well as the reaction efficiency as a function of the fuel input rate was determined, and a comparison between the performances of different plates is discussed.

  14. A new class of photo-catalytic materials and a novel principle for efficient water splitting under infrared and visible light - MgB2 as unexpected example

    CERN Document Server

    Kravets, V G

    2015-01-01

    Water splitting is unanimously recognized as environment friendly, potentially low cost and renewable energy solution based on the future hydrogen economy. Especially appealing is photo-catalytic water splitting whereby a suitably chosen catalyst dramatically improves efficiency of the hydrogen production driven by direct sunlight and allows it to happen even at zero driving potential. Here, we suggest a new class of stable photo-catalysts and the corresponding principle for catalytic water splitting in which infrared and visible light play the main role in producing the photocurrent and hydrogen. The new class of catalysts based on ionic binary metals with layered graphite-like structures which effectively absorb visible and infrared light facilitating the reaction of water splitting, suppress the inverse reaction of ion recombination by separating ions due to internal electric fields existing near alternating layers, provide the sites for ion trapping of both polarities, and finally deliver the electrons an...

  15. ONO-pincer ruthenium complex-bound norvaline for efficient catalytic oxidation of methoxybenzenes with hydrogen peroxide.

    Science.gov (United States)

    Yoshida, Ryota; Isozaki, Katsuhiro; Yokoi, Tomoya; Yasuda, Nobuhiro; Sadakane, Koichiro; Iwamoto, Takahiro; Takaya, Hikaru; Nakamura, Masaharu

    2016-08-21

    The enhanced catalytic activity of ruthenium complex-bound norvaline Boc-l-[Ru]Nva-OMe 1, in which the ONO-pincer ruthenium complex Ru(pydc)(terpy) 2 is tethered to the α-side chain of norvaline, has been demonstrated for the oxidation of methoxybenzenes to p-benzoquinones with a wide scope of substrates and unique chemoselectivity. PMID:27314504

  16. Study of the technology of the plasma nanostructuring of silicon to form highly efficient emission structures

    Energy Technology Data Exchange (ETDEWEB)

    Galperin, V. A.; Kitsyuk, E. P. [“Technological Center” Research-and-Production Company (Russian Federation); Pavlov, A. A. [Russian Academy of Sciences, Institute of Nanotechnologies in Microelectronics (Russian Federation); Shamanaev, A. A., E-mail: artemiy.shamanaev@tcen.ru [“Technological Center” Research-and-Production Company (Russian Federation)

    2015-12-15

    New methods for silicon nanostructuring and the possibility of raising the aspect ratios of the structures being formed are considered. It is shown that the technology developed relates to self-formation methods and is an efficient tool for improving the quality of field-emission cathodes based on carbon nanotubes (CNTs) by increasing the Si–CNT contact area and raising the efficiency of the heat sink.

  17. Market Returns and Weak-Form Efficiency: the case of the Ghana Stock Exchange

    OpenAIRE

    Frimpong, Joseph Magnus; Oteng-Abayie, Eric Fosu

    2007-01-01

    This paper examines the weak-form efficient market hypothesis (EMH) in the case of the Ghana Stock Exchange (GSE) an emerging market. Daily returns from the Databank Stock Index (DSI) over a 5-year period 1999-2004 were used for the exercise. Random walk (RW) and GARCH(1,1) models are used as the basis for our analysis. The GSE DSI returns series exhibit volatility clustering, an indication of inefficiency on the GSE. The weak-form efficient market (random walk) hypothesis was rejected for t...

  18. Testing the Weak-Form Market Efficiency of the Euronext Wheat

    Directory of Open Access Journals (Sweden)

    Mihai Cristian Dinică

    2015-03-01

    Full Text Available Using a trading system based on various simple moving average crossings, the paper examines the weak-form market efficiency of the wheat traded at the Euronext exchange. After optimizing over the sample period, the best strategy is selected and then applied over the out-of-sample period. The profitability of this strategy is then compared with the simple buy and hold strategy. The methodology is then repeated for different sub-samples in order to check the results’ robustness. The results show that the weak-form market efficiency hypothesis cannot be rejected for the wheat case.

  19. A non-acid-assisted and non-hydroxyl-radical-related catalytic ozonation with ceria supported copper oxide in efficient oxalate degradation in water

    KAUST Repository

    Zhang, Tao

    2012-06-01

    Oxalate is usually used as a refractory model compound that cannot be effectively removed by ozone and hydroxyl radical oxidation in water. In this study, we found that ceria supported CuO significantly improved oxalate degradation in reaction with ozone. The optimum CuO loading amount was 12%. The molar ratio of oxalate removed/ozone consumption reached 0.84. The catalytic ozonation was most effective in a neutral pH range (6.7-7.9) and became ineffective when the water solution was acidic or alkaline. Moreover, bicarbonate, a ubiquitous hydroxyl radical scavenger in natural waters, significantly improved the catalytic degradation of oxalate. Therefore, the degradation relies on neither hydroxyl radical oxidation nor acid assistance, two pathways usually proposed for catalytic ozonation. These special characters of the catalyst make it suitable to be potentially used for practical degradation of refractory hydrophilic organic matter and compounds in water and wastewater. With in situ characterization, the new surface Cu(II) formed from ozone oxidation of the trace Cu(I) of the catalyst was found to be an active site in coordination with oxalate forming multi-dentate surface complex. It is proposed that the complex can be further oxidized by molecular ozone and then decomposes through intra-molecular electron transfer. The ceria support enhanced the activity of the surface Cu(I)/Cu(II) in this process. © 2012 Elsevier B.V.

  20. Optimizing front metallization patterns: Efficiency with aesthetics in free-form solar cells

    NARCIS (Netherlands)

    Gupta, D.K.; Langelaar, M.; Barink, M.; Keulen, F. van

    2016-01-01

    Free-form solar cells are cells of unconventional shapes (e.g. hexagonal, leaf-shaped etc). Their flexible shape adds to the aesthetics of the surroundings as well as allows to place them over objects where conventional solar cells might not fit. Evidently, these cells need to be efficient as well,

  1. FORMING OF THE SUSTAINABLE SUPPLY CHAINS BASED ON INCREASING OF THEIR INTEGRATED ENERGY EFFICIENCY

    Directory of Open Access Journals (Sweden)

    SHVETS V. J.

    2016-03-01

    Full Text Available Purpose. Key challenges and barriers of mining machinery enterprises in the context of forming sustainable supply chains in the mining industry are specified. Methodology. The algorithm of forming the industrial relations, which are carried out by the enterprises of mining machinery in order to increase the sustainable development of a mining industry, is offered. Conclusions.. Modern supply chains are confronted with dynamic trends and developments that are hard to predict. In order to respond to these changes and remain competitive advantage, companies should be able to identify and understand new sustainability issues in their branches. It is established that in the conditions of globalization of the market and the general orientation of Ukraine’s economy to the European principles of development, for mining machinery enterprises a proof of the commitment and observance of requirements of energy efficiency, i.e. energy saving, energy safety and social energy responsibility are very important. Supply channels should increase not only energy efficiency, economic and production stability of the company, but also strengthen the stability of all participants in the production chain, as well as other stakeholders (business partners, customers, investors, local communities, etc.. Originality. The interrelation of an indicator of energy efficiency in forming sustainable supply chain in a mining industry is established. Practical value. Using the principles of sustainable development in the forming of value chains will improve energy efficiency of industry in general; provide a competitive advantage to entry into the global production chains in terms of European integration of Ukraine.

  2. Synthesis, characterization and study of catalytic activity of Silver doped ZnO nanocomposite as an efficient catalyst for selective oxidation of benzyl alcohol

    Indian Academy of Sciences (India)

    A Fallah Shojaei; K Tabatabaeian; M A Zanjanchi; H Fallah Moafi; N Modirpanah

    2015-03-01

    Powder samples of Ag/ZnO nanocomposite containing different amounts of Ag were synthesized by co-precipitation method. The synthesized samples were characterized by XRD, SEM, EDX and TEM techniques. The XRD results revealed that all the samples show wurtzite hexagonal phase of ZnO. The TEM micrographs of the samples showed that size of Ag-ZnO nanoparticles was in the range of 30–50 nm. Catalytic activity was tested using liquid-phase selective oxidation of benzylic alcohols to aldehydes. The influence of some parameters such as optimum weight of Ag, catalyst dosage, oxidant and various solvents were studied. The superior catalytic performance of the Ag/ZnO nanocomposite was observed in microwave condition compared to that performed in reflux condition. The catalysts were recycled three times in the oxidation of alcohols and little change in the conversion efficiency was observed. The highly dispersed Ag metal particles on ZnO surface was considered to be responsible for the catalytic activity.

  3. Cellular graphene aerogel combines ultralow weight and high mechanical strength: A highly efficient reactor for catalytic hydrogenation.

    Science.gov (United States)

    Zhang, Bingxing; Zhang, Jianling; Sang, Xinxin; Liu, Chengcheng; Luo, Tian; Peng, Li; Han, Buxing; Tan, Xiuniang; Ma, Xue; Wang, Dong; Zhao, Ning

    2016-05-12

    The construction of three-dimensional graphene aerogels (GAs) is of great importance owing to their outstanding properties for various applications. Up to now, the combination of ultralow weight and super mechanical strength for GA remains a great challenge. Here we demonstrate the fabrication of cellular GAs by a facile, easily controlled and versatile route, i.e. the chemical reduction of graphene oxide assemblies at oil-water interface under a mild condition (70 °C). The GA is ultralight (with density <3 mg cm(-3)) yet mechanically resilient because the walls of the cell closely pack in a highly ordered manner to maximize mechanical strength. The GA has been utilized as an appealing reactor for catalytic hydrogenation, which exhibited great advantages such as large oil absorption capability, exceptional catalytic activity, ease of product separation and high stability.

  4. 3D hierarchical walnut-like CuO nanostructures: Preparation, characterization and their efficient catalytic activity for CO oxidation

    Science.gov (United States)

    Yao, Weitang; Zhang, Yujuan; Duan, Tao; Zhu, Wenkun; Yi, Zao; Cui, Xudong

    2016-07-01

    In this work, 3D hierarchical walnut-shaped, 2D nanosheet and 3D microspheres single phase CuO nanostructures are functioning as catalysts and supporting materials, differing from the conventional ways. The novel nanostructures were synthesized via hydrothermal method under a stainless steel autoclave. The as-prepared materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and H2 temperature-programmed reduction (H2-TPR). The walnut-shaped structures with high O/Cu atomic ratio (1.22) exhibit high oxygen adsorption capacity and greatly enhanced catalytic activity. These results will be enrich the techniques for tuning the morphologies of metal oxide micro/nanostructures and open a new field in catalytic applications.

  5. Cellular graphene aerogel combines ultralow weight and high mechanical strength: A highly efficient reactor for catalytic hydrogenation

    Science.gov (United States)

    Zhang, Bingxing; Zhang, Jianling; Sang, Xinxin; Liu, Chengcheng; Luo, Tian; Peng, Li; Han, Buxing; Tan, Xiuniang; Ma, Xue; Wang, Dong; Zhao, Ning

    2016-05-01

    The construction of three-dimensional graphene aerogels (GAs) is of great importance owing to their outstanding properties for various applications. Up to now, the combination of ultralow weight and super mechanical strength for GA remains a great challenge. Here we demonstrate the fabrication of cellular GAs by a facile, easily controlled and versatile route, i.e. the chemical reduction of graphene oxide assemblies at oil-water interface under a mild condition (70 °C). The GA is ultralight (with density resilient because the walls of the cell closely pack in a highly ordered manner to maximize mechanical strength. The GA has been utilized as an appealing reactor for catalytic hydrogenation, which exhibited great advantages such as large oil absorption capability, exceptional catalytic activity, ease of product separation and high stability.

  6. Cellular graphene aerogel combines ultralow weight and high mechanical strength: A highly efficient reactor for catalytic hydrogenation.

    Science.gov (United States)

    Zhang, Bingxing; Zhang, Jianling; Sang, Xinxin; Liu, Chengcheng; Luo, Tian; Peng, Li; Han, Buxing; Tan, Xiuniang; Ma, Xue; Wang, Dong; Zhao, Ning

    2016-01-01

    The construction of three-dimensional graphene aerogels (GAs) is of great importance owing to their outstanding properties for various applications. Up to now, the combination of ultralow weight and super mechanical strength for GA remains a great challenge. Here we demonstrate the fabrication of cellular GAs by a facile, easily controlled and versatile route, i.e. the chemical reduction of graphene oxide assemblies at oil-water interface under a mild condition (70 °C). The GA is ultralight (with density <3 mg cm(-3)) yet mechanically resilient because the walls of the cell closely pack in a highly ordered manner to maximize mechanical strength. The GA has been utilized as an appealing reactor for catalytic hydrogenation, which exhibited great advantages such as large oil absorption capability, exceptional catalytic activity, ease of product separation and high stability. PMID:27174450

  7. Computational Efficient Upscaling Methodology for Predicting Thermal Conductivity of Nuclear Waste forms

    Energy Technology Data Exchange (ETDEWEB)

    Li, Dongsheng; Sun, Xin; Khaleel, Mohammad A.

    2011-09-28

    This study evaluated different upscaling methods to predict thermal conductivity in loaded nuclear waste form, a heterogeneous material system. The efficiency and accuracy of these methods were compared. Thermal conductivity in loaded nuclear waste form is an important property specific to scientific researchers, in waste form Integrated performance and safety code (IPSC). The effective thermal conductivity obtained from microstructure information and local thermal conductivity of different components is critical in predicting the life and performance of waste form during storage. How the heat generated during storage is directly related to thermal conductivity, which in turn determining the mechanical deformation behavior, corrosion resistance and aging performance. Several methods, including the Taylor model, Sachs model, self-consistent model, and statistical upscaling models were developed and implemented. Due to the absence of experimental data, prediction results from finite element method (FEM) were used as reference to determine the accuracy of different upscaling models. Micrographs from different loading of nuclear waste were used in the prediction of thermal conductivity. Prediction results demonstrated that in term of efficiency, boundary models (Taylor and Sachs model) are better than self consistent model, statistical upscaling method and FEM. Balancing the computation resource and accuracy, statistical upscaling is a computational efficient method in predicting effective thermal conductivity for nuclear waste form.

  8. High efficiency chemical energy conversion system based on a methane catalytic decomposition reaction and two fuel cells. Part II. Exergy analysis

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Qinghua; Tian, Ye; Li, Hongjiao; Jia, Lijun; Xia, Chun; Li, Yongdan [Tianjin Key Laboratory of Catalysis Science and Technology and State Key Laboratory for Chemical Engineering (Tianjin University), School of Chemical Engineering, Tianjin University, Tianjin 300072 (China); Thompson, Levi T. [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109-2136 (United States)

    2010-10-01

    A methane catalytic decomposition reactor-direct carbon fuel cell-internal reforming solid oxide fuel cell (MCDR-DCFC-IRSOFC) energy system is highly efficient for converting the chemical energy of methane into electrical energy. A gas turbine cycle is also used to output more power from the thermal energy generated in the IRSOFC. In part I of this work, models of the fuel cells and the system are proposed and validated. In this part, exergy conservation analysis is carried out based on the developed electrochemical and thermodynamic models. The ratio of the exergy destruction of each unit is examined. The results show that the electrical exergy efficiency of 68.24% is achieved with the system. The possibility of further recovery of the waste heat is discussed and the combined power-heat exergy efficiency is over 80%. (author)

  9. Optimizing carbon efficiency of jet fuel range alkanes from cellulose co-fed with polyethylene via catalytically combined processes.

    Science.gov (United States)

    Zhang, Xuesong; Lei, Hanwu; Zhu, Lei; Zhu, Xiaolu; Qian, Moriko; Yadavalli, Gayatri; Yan, Di; Wu, Joan; Chen, Shulin

    2016-08-01

    Enhanced carbon yields of renewable alkanes for jet fuels were obtained through the catalytic microwave-induced co-pyrolysis and hydrogenation process. The well-promoted ZSM-5 catalyst had high selectivity toward C8-C16 aromatic hydrocarbons. The raw organics with improved carbon yield (∼44%) were more principally lumped in the jet fuel range at the catalytic temperature of 375°C with the LDPE to cellulose (representing waste plastics to lignocellulose) mass ratio of 0.75. It was also observed that the four species of raw organics from the catalytic microwave co-pyrolysis were almost completely converted into saturated hydrocarbons; the hydrogenation process was conducted in the n-heptane medium by using home-made Raney Ni catalyst under a low-severity condition. The overall carbon yield (with regards to co-reactants of cellulose and LDPE) of hydrogenated organics that mostly match jet fuels was sustainably enhanced to above 39%. Meanwhile, ∼90% selectivity toward jet fuel range alkanes was attained. PMID:27126079

  10. Malaysian finance sector weak-form efficiency: Heterogeneity, structural breaks, and cross-sectional dependence

    Directory of Open Access Journals (Sweden)

    Sook Ching Kok

    2015-12-01

    Full Text Available This study examines the weak-form efficient market hypothesis (EMH for the Finance Sector in Malaysian Stock Exchange, by exploring and scrutinizing the firm-level efficiency over for the period from 1st January 1997 to 31st December 2014. For this purpose, we apply panel nonlinear unit root test that accounts for heterogeneity, and panel stationarity test to allow for the presence of structural breaks and cross-sectional dependence (CSD. The main findings of this study suggest the following: first, there is a strong CSD among the price series of finance stocks; second, unlike the traditional panel unit root tests that provide mixed-results, the panel stationarity test which incorporates structural breaks and CSD suggests that these series are characterized as random walk processes implying the Finance Sector is weak-form efficient. The finding of weak-form efficiency has salient implications in terms of capital allocation, stock price predictability, forecasting technique, and the impact of shocks to stock prices.

  11. Energy Efficiency in Architecture – a Technical Obstacle or a Chance to Find new Forms?

    Directory of Open Access Journals (Sweden)

    Shchepetkov Nikolai

    2016-01-01

    Full Text Available The article exposes innovative materials and structures for improving the energy efficiency of lightning in architecture. The problem of architectural energy efficiency and its part – energy saving illumination of rooms and urban environment is very actual in developing countries. This problem can be successfully solved only by a complex of architectural, constructional, electrical and technological measures which will lead to new forms in architecture and lightning design. This article briefly reviews the benefits of light pipes technologies to enhance natural illumination of deep plan buildings.

  12. An efficient closed-form solution for acoustic emission source location in three-dimensional structures

    Directory of Open Access Journals (Sweden)

    Xibing Li

    2014-02-01

    Full Text Available This paper presents an efficient closed-form solution (ECS for acoustic emission(AE source location in three-dimensional structures using time difference of arrival (TDOA measurements from N receivers, N ≥ 6. The nonlinear location equations of TDOA are simplified to linear equations. The unique analytical solution of AE sources for unknown velocity system is obtained by solving the linear equations. The proposed ECS method successfully solved the problems of location errors resulting from measured deviations of velocity as well as the existence and multiplicity of solutions induced by calculations of square roots in existed close-form methods.

  13. An efficient closed-form solution for acoustic emission source location in three-dimensional structures

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xibing [School of Resources and Safety Engineering, Central South University, Changsha, 410083 (China); Dong, Longjun, E-mail: csudlj@163.com [School of Resources and Safety Engineering, Central South University, Changsha, 410083 (China); Australian Centre for Geomechanics, The University of Western Australia, Crawley, 6009 (Australia)

    2014-02-15

    This paper presents an efficient closed-form solution (ECS) for acoustic emission(AE) source location in three-dimensional structures using time difference of arrival (TDOA) measurements from N receivers, N ≥ 6. The nonlinear location equations of TDOA are simplified to linear equations. The unique analytical solution of AE sources for unknown velocity system is obtained by solving the linear equations. The proposed ECS method successfully solved the problems of location errors resulting from measured deviations of velocity as well as the existence and multiplicity of solutions induced by calculations of square roots in existed close-form methods.

  14. Testing the Week Form Efficiency of Pakistani Stock Market (2000-2010

    Directory of Open Access Journals (Sweden)

    Abdul Haque

    2011-01-01

    Full Text Available This empirical paper tests out the weak form efficiency of Pakistani stock market by examining the weekly index over the period . Return series has a leptokurtic and negatively skewed distribution, which is away from normal distribution as reflected by significant Jarque-Bera statistic. Estimated results of ADF (1979, PP (1988 and KPSS (1992 tests, Ljung-Box Q-Statistic of autocorrelations and runs test of randomness reject the Random Walk Hypothesis (RWH for the returns series. Moreover the results of variance ratio test (Lo and MacKinlay (1988 also reject the RWH and prove the robustness of other estimated results. The rejection of RWH reveals that the Pakistani stock prices are not Weak Form Efficient.

  15. Weak Form Efficiency of the Nigerian Stock Market: An Empirical Analysis (1984 – 2009

    Directory of Open Access Journals (Sweden)

    Pyemo Afego

    2012-01-01

    Full Text Available This paper examines the weak-form of the efficient markets hypothesis for the Nigerian Stock Exchange (NSE by testing for random walks in the monthly index returns over the period 1984-2009. The results of the non-parametric runs test show that index returns on the NSE display a predictable component, thus suggesting that traders can earn superior returns by employing trading rules. Statistically significant deviations from randomness are also suggestive of sub-optimal allocation of investment capital within the economy. The findings, in general, contradict the weak-form of the efficient markets hypothesis, and a range of policy strategies for improving the allocative capacity and quality of the information environment of the NSE are discussed.

  16. Triplex-forming oligonucleotide–orthophenanthroline conjugates for efficient targeted genome modification

    OpenAIRE

    Cannata, Fabio; Brunet, Erika; Perrouault, Loïc; Roig, Victoria; Ait-Si-Ali, Slimane; Asseline, Ulysse; Concordet, Jean-Paul; Giovannangeli, Carine

    2008-01-01

    The inefficiency of gene modification by homologous recombination can be overcome by the introduction of a double-strand break (DSB) in the target. Engineering the endonucleases needed, however, remains a challenging task that limits widespread application of nuclease-driven gene modification. We report here that conjugates of orthophenanthroline (OP), a DNA cleaving molecule, and triplex-forming oligonucleotides (TFOs), known to bind specific DNA sequences, are synthetic nucleases efficient ...

  17. Weak-form Efficiency of Carbon Trading Markets: Evidence from Bluenext Spot Market

    OpenAIRE

    Shams, Mariam

    2013-01-01

    ABSTRACT: Reducing the greenhouse gases is urgent need in this century, to see this target several cap and trade markets are working around the world trading emission allowances. Bluenext market is the largest and most liquide one. The aim of this study is to investigate the weak-form efficiency of this market. The EUAs ( European Union Allowances) have been traded in two phases since 2005 in Bluenext market. Related to several structural breaks in the time series 4 parametric tests employed ...

  18. Testing the weak-form efficiency of the WTI crude oil futures market

    Science.gov (United States)

    Jiang, Zhi-Qiang; Xie, Wen-Jie; Zhou, Wei-Xing

    2014-07-01

    The weak-form efficiency of energy futures markets has long been studied and empirical evidence suggests controversial conclusions. In this work, nonparametric methods are adopted to estimate the Hurst indexes of the WTI crude oil futures prices (1983-2012) and a strict statistical test in the spirit of bootstrapping is put forward to verify the weak-form market efficiency hypothesis. The results show that the crude oil futures market is efficient when the whole period is considered. When the whole series is divided into three sub-series separated by the outbreaks of the Gulf War and the Iraq War, it is found that the Gulf War reduced the efficiency of the market. If the sample is split into two sub-series based on the signing date of the North American Free Trade Agreement, the market is found to be inefficient in the sub-periods during which the Gulf War broke out. The same analysis on short-time series in moving windows shows that the market is inefficient only when some turbulent events occur, such as the oil price crash in 1985, the Gulf war, and the oil price crash in 2008.

  19. Robust Approach to Verifying the Weak Form of the Efficient Market Hypothesis

    Science.gov (United States)

    Střelec, Luboš

    2011-09-01

    The weak form of the efficient markets hypothesis states that prices incorporate only past information about the asset. An implication of this form of the efficient markets hypothesis is that one cannot detect mispriced assets and consistently outperform the market through technical analysis of past prices. One of possible formulations of the efficient market hypothesis used for weak form tests is that share prices follow a random walk. It means that returns are realizations of IID sequence of random variables. Consequently, for verifying the weak form of the efficient market hypothesis, we can use distribution tests, among others, i.e. some tests of normality and/or some graphical methods. Many procedures for testing the normality of univariate samples have been proposed in the literature [7]. Today the most popular omnibus test of normality for a general use is the Shapiro-Wilk test. The Jarque-Bera test is the most widely adopted omnibus test of normality in econometrics and related fields. In particular, the Jarque-Bera test (i.e. test based on the classical measures of skewness and kurtosis) is frequently used when one is more concerned about heavy-tailed alternatives. As these measures are based on moments of the data, this test has a zero breakdown value [2]. In other words, a single outlier can make the test worthless. The reason so many classical procedures are nonrobust to outliers is that the parameters of the model are expressed in terms of moments, and their classical estimators are expressed in terms of sample moments, which are very sensitive to outliers. Another approach to robustness is to concentrate on the parameters of interest suggested by the problem under this study. Consequently, novel robust testing procedures of testing normality are presented in this paper to overcome shortcomings of classical normality tests in the field of financial data, which are typical with occurrence of remote data points and additional types of deviations from

  20. Carbon nanotube growth from catalytic nano-clusters formed by hot-ion-implantation into the SiO{sub 2}/Si interface

    Energy Technology Data Exchange (ETDEWEB)

    Hoshino, Yasushi, E-mail: yhoshino@kanagawa-u.ac.jp [Department of Information Sciences, Kanagawa University, 2946 Tsuchiya, Hiratsuka, Kanagawa 259-1293 (Japan); Arima, Hiroki; Yokoyama, Ai; Saito, Yasunao; Nakata, Jyoji [Department of Information Sciences, Kanagawa University, 2946 Tsuchiya, Hiratsuka, Kanagawa 259-1293 (Japan)

    2012-07-01

    We have studied growth of chirality-controlled carbon nanotubes (CNTs) from hot-implantation-formed catalytic nano-clusters in a thermally grown SiO{sub 2}/Si substrate. This procedure has the advantage of high controllability of the diameter and the number of clusters by optimizing the conditions of the ion implantation. In the present study, Co{sup +} ions with ion dose of 8 Multiplication-Sign 10{sup 16} cm{sup -2} are implanted in the vicinity of the SiO{sub 2}/Si interface at 300 Degree-Sign C temperature. The implanted Co atoms located in the SiO{sub 2} layer has an amorphous-like structure with a cluster diameter of several nm. In contrast, implanted Co atoms in the Si substrate are found to take a cobalt silicide structure, confirmed by the high-resolution image of transmission electron microscope. CNTs are grown by microwave-plasma-enhanced chemical vapor deposition. We have confirmed a large amount of vertically-aligned multi-walled CNTs from the Co nano-clusters formed by the hot-ion-implantation near the SiO{sub 2}/Si interface.

  1. Highly Dense Isolated Metal Atom Catalytic Sites

    DEFF Research Database (Denmark)

    Chen, Yaxin; Kasama, Takeshi; Huang, Zhiwei;

    2015-01-01

    -ray diffraction. A combination of electron microscopy images with X-ray absorption spectra demonstrated that the silver atoms were anchored on five-fold oxygen-terminated cavities on the surface of the support to form highly dense isolated metal active sites, leading to excellent reactivity in catalytic oxidation......Atomically dispersed noble-metal catalysts with highly dense active sites are promising materials with which to maximise metal efficiency and to enhance catalytic performance; however, their fabrication remains challenging because metal atoms are prone to sintering, especially at a high metal...... loading. A dynamic process of formation of isolated metal atom catalytic sites on the surface of the support, which was achieved starting from silver nanoparticles by using a thermal surface-mediated diffusion method, was observed directly by using in situ electron microscopy and in situ synchrotron X...

  2. Solubilization and Iterative Saturation Mutagenesis of α1,3-fucosyltransferase from Helicobacter pylori to enhance its catalytic efficiency.

    Science.gov (United States)

    Choi, Yun Hee; Kim, Jong Hoon; Park, Bum Seok; Kim, Byung-Gee

    2016-08-01

    α1,3-Fucosyltransferase (α1,3-FucT) is essential for the biosynthesis of biologically active α1,3-fucosyloligosacchairdes (3-FOs) from human milk oligosaccharides (HMO), particularly 3-fucosyllactose (3-FL) trisaccharide. α1,3-FucT from Helicobacter pylori 26695 (FutA) accepts lactose and LacNAc as glycan acceptors and has a very low level of expression in Escherichia coli, and it shows a low catalytic activity for lactose in the large-scale synthesis of 3-FL. To overcome the poor solubility of FutA, codon optimization, and systematic truncation of the protein at the C-terminus with only one heptad repeat remaining (Δ52 FutA) were conducted to yield 150-200 mg/L of soluble protein of FutA and resulting in more than an 18-fold increase in the 3-FL yield. To improve the low level of enzyme catalytic activity for lactose, focused directed evolution was attempted using a semi-rational approach that combines structure-guided computational analysis and subsequent iterative saturation mutagenesis (ISM). In order to select the functional residues in active site/substrate binding site, docking simulation was used together with HotSpot Wizard to target evolutionarily variable amino acid positions. A128 site was selected from the key residue located in the active site, and A128N mutant displayed a 3.4-fold higher catalytic activity than wild-type Δ52 FutA. Considering that the A128N mutation is located in the deep cleft of the lactose binding site, the residues within the substrate binding sites, especially on the two α-helices for lactose and one α-helix for GDP-fucose, were subjected to structure-guided ISM. The selected residues from each helix were clustered, and ISM was performed for each cluster in parallel. In particular, the mutant with triple mutations (A128N/H129E/Y132I) located on the α5 helix exhibited a 9.6-fold improvement in specific activity when compared to wild-type Δ52 FutA. When such clustered mutations on two α-helices (α5 and α2/loop) were

  3. Testing Weak-Form Efficiency of The Chinese Stock Market and Hong Kong Stock Market

    OpenAIRE

    Lei, Zhuolin

    2012-01-01

    This study examines the random walk hypothesis to determine the validity of weak-form efficiency for Shanghai, Shenzhen and Hong Kong Stock Exchanges. Daily returns from 2001-2010 for Shanghai A and B shares, Shenzhen A and B shares and Hong Kong Hang Seng Index are used in this study. The random walk hypothesis is examined by using four statistical methods, namely a serial correlation test, an Augmented Dickey-Fuller Unit Root test, a runs test and a variance ratio test. The empirical re...

  4. Toward efficient nanoporous catalysts: controlling site-isolation and concentration of grafted catalytic sites on nanoporous materials with solvents and colorimetric elucidation of their site-isolation.

    Science.gov (United States)

    Sharma, Krishna K; Anan, Abhishek; Buckley, Robert P; Ouellette, Wayne; Asefa, Tewodros

    2008-01-01

    We report that the polarity and dielectric constants of solvents used for grafting organosilanes on mesoporous materials strongly affect the concentration of grafted organic groups, the degree of their site-isolation, and the catalytic properties of the resulting materials. Polar and nonpolar organosilanes as well as polar-protic, dipolar-aprotic, and nonpolar solvents were investigated. Polar-protic solvents, which have high dielectric constants, resulted in smaller concentrations ( approximately 1-2 mmol/g) of polar organic groups such as 3-aminopropyl groups, higher surface area materials, site-isolated organic groups, and more efficient catalytic properties toward the Henry reaction of p-hydroxybenzaldehyde with nitromethane. On the other hand, dipolar-aprotic and nonpolar solvents resulted in larger concentrations ( approximately 2-3 mmol/g) of grafted polar functional groups, lower-to-higher surface area materials, more densely populated catalytic groups, and poor-to-efficient catalytic properties toward the Henry reaction. Both the polar-protic and dipolar-aprotic solvents resulted in significantly lower concentration of grafted groups for nonpolar organosilanes such as (3-mercaptopropyl)trimethoxysilane compared to corresponding grafting of the polar amino-organosilanes. The relationship between the solvent properties and the percentage and degree of site-isolation of the grafted functional groups was attributed to differences in solvation of the organosilanes and silanols in various solvents and possible hydrogen-bonding between the organsilanes and the solvents. The degree of site-isolation of the amine groups, which affect the material's catalytic properties, was elucidated by a new colorimetric method involving probing of the absorption maxima (lambdamax) on the d-d electronic spectrum of Cu2+ complexes with the amine-functionalized materials and the colors of the samples. The absorption lambdamax and the colors of the materials were found to be

  5. Physico-Chemical Condition Optimization during Biosynthesis lead to development of Improved and Catalytically Efficient Gold Nano Particles.

    Science.gov (United States)

    Kumari, Madhuree; Mishra, Aradhana; Pandey, Shipra; Singh, Satyendra Pratap; Chaudhry, Vasvi; Mudiam, Mohana Krishna Reddy; Shukla, Shatrunajay; Kakkar, Poonam; Nautiyal, Chandra Shekhar

    2016-01-01

    Biosynthesis of nanoparticles has gained great attention in making the process cost-effective and eco-friendly, but there are limited reports which describe the interdependency of physical parameters for tailoring the dimension and geometry of nanoparticles during biological synthesis. In the present study, gold nanoparticles (GNPs) of various shapes and sizes were obtained by modulating different physical parameters using Trichoderma viride filtrate. The particles were characterized on the basis of visual observation, dynamic light scattering, UV-visible spectroscopy, transmission electron microscopy, fourier transform infrared spectroscopy, and X ray diffraction. While the size varied from 2-500 nm, the shapes obtained were nanospheres, nanotriangles, nanopentagons, nanohexagons, and nanosheets. Changing the parameters such as pH, temperature, time, substrate, and culture filtrate concentration influenced the size and geometry of nanoparticles. Catalytic activity of the biosynthesized GNP was evaluated by UV-visible spectroscopy and confirmed by gas chromatography-mass spectrometric analysis for the conversion of 4-nitrophenol into 4-aminophenol which was strongly influenced by their structure and dimension. Common practices for biodegradation are traditional, expensive, require large amount of raw material, and time taking. Controlling shapes and sizes of nanoparticles could revolutionize the process of biodegradation that can remove all the hurdles in current scenario. PMID:27273371

  6. Physico-Chemical Condition Optimization during Biosynthesis lead to development of Improved and Catalytically Efficient Gold Nano Particles

    Science.gov (United States)

    Kumari, Madhuree; Mishra, Aradhana; Pandey, Shipra; Singh, Satyendra Pratap; Chaudhry, Vasvi; Mudiam, Mohana Krishna Reddy; Shukla, Shatrunajay; Kakkar, Poonam; Nautiyal, Chandra Shekhar

    2016-01-01

    Biosynthesis of nanoparticles has gained great attention in making the process cost-effective and eco-friendly, but there are limited reports which describe the interdependency of physical parameters for tailoring the dimension and geometry of nanoparticles during biological synthesis. In the present study, gold nanoparticles (GNPs) of various shapes and sizes were obtained by modulating different physical parameters using Trichoderma viride filtrate. The particles were characterized on the basis of visual observation, dynamic light scattering, UV-visible spectroscopy, transmission electron microscopy, fourier transform infrared spectroscopy, and X ray diffraction. While the size varied from 2–500 nm, the shapes obtained were nanospheres, nanotriangles, nanopentagons, nanohexagons, and nanosheets. Changing the parameters such as pH, temperature, time, substrate, and culture filtrate concentration influenced the size and geometry of nanoparticles. Catalytic activity of the biosynthesized GNP was evaluated by UV-visible spectroscopy and confirmed by gas chromatography-mass spectrometric analysis for the conversion of 4-nitrophenol into 4-aminophenol which was strongly influenced by their structure and dimension. Common practices for biodegradation are traditional, expensive, require large amount of raw material, and time taking. Controlling shapes and sizes of nanoparticles could revolutionize the process of biodegradation that can remove all the hurdles in current scenario. PMID:27273371

  7. Utilizing metal tolerance potential of soil fungus for efficient synthesis of gold nanoparticles with superior catalytic activity for degradation of rhodamine B.

    Science.gov (United States)

    Bhargava, Arpit; Jain, Navin; Khan, Mohd Azeem; Pareek, Vikram; Dilip, R Venkataramana; Panwar, Jitendra

    2016-12-01

    In recent years, the surging demand of nanomaterials has boosted unprecedented expansion of research for the development of high yielding and sustainable synthesis methods which can deliver nanomaterials with desired characteristics. Unlike the well-established physico-chemical methods which have various limitations, biological methods inspired by mimicking natural biomineralization processes have great potential for nanoparticle synthesis. An eco-friendly and sustainable biological method that deliver particles with well-defined shape, size and compositions can be developed by selecting a proficient organism followed by fine tuning of various process parameter. The present study revealed high metal tolerance ability of a soil fungus Cladosporium oxysporum AJP03 and its potential for extracellular synthesis of gold nanoparticles. The morphology, composition and crystallinity of nanoparticles were confirmed using standard techniques. The synthesized particles were quasi-spherical in shape with fcc packing and an average particle size of 72.32 ± 21.80 nm. A series of experiments were conducted to study the effect of different process parameters on particle size and yield. Biomass: water ratio of 1:5 and 1 mM precursor salt concentration at physiological pH (7.0) favoured the synthesis of well-defined gold nanoparticles with maximum yield. The as-synthesized nanoparticles showed excellent catalytic efficiency towards sodium borohydride mediated reduction of rhodamine B (2.5 × 10(-5) M) within 7 min of reaction time under experimental conditions. Presence of proteins as capping material on the nanoparticle surface was found to be responsible for this remarkable catalytic efficiency. The present approach can be extrapolated to develop controlled and up-scalable process for mycosynthesis of nanoparticles for diverse applications. PMID:27567934

  8. Triplex-forming oligonucleotide-orthophenanthroline conjugates for efficient targeted genome modification.

    Science.gov (United States)

    Cannata, Fabio; Brunet, Erika; Perrouault, Loïc; Roig, Victoria; Ait-Si-Ali, Slimane; Asseline, Ulysse; Concordet, Jean-Paul; Giovannangeli, Carine

    2008-07-15

    The inefficiency of gene modification by homologous recombination can be overcome by the introduction of a double-strand break (DSB) in the target. Engineering the endonucleases needed, however, remains a challenging task that limits widespread application of nuclease-driven gene modification. We report here that conjugates of orthophenanthroline (OP), a DNA cleaving molecule, and triplex-forming oligonucleotides (TFOs), known to bind specific DNA sequences, are synthetic nucleases efficient at stimulating targeted genome modification. We show that in cultured cells, OP-TFO conjugates induce targeted DSBs. An OP-TFO with a unique target was highly efficient, and mutations at the target site were found in approximately 10% of treated cells, including small deletions most likely introduced during DSB repair by nonhomologous end joining. Importantly, we found that when homologous donor DNA was cotransfected, targeted gene modification took place in >1.5% of treated cells. Because triplex-forming sequences are frequent in human and mouse genes, OP-TFO conjugates therefore constitute an important class of site-specific nucleases for targeted gene modification. Harnessing DNA-damaging molecules to predetermined genomic sites, as achieved here, should also provide inroads into mechanisms of DNA repair and cancer. PMID:18599454

  9. Directed evolution of Tau class glutathione transferases reveals a site that regulates catalytic efficiency and masks co-operativity.

    Science.gov (United States)

    Axarli, Irine; Muleta, Abdi W; Vlachakis, Dimitrios; Kossida, Sophia; Kotzia, Georgia; Maltezos, Anastasios; Dhavala, Prathusha; Papageorgiou, Anastassios C; Labrou, Nikolaos E

    2016-03-01

    A library of Tau class GSTs (glutathione transferases) was constructed by DNA shuffling using the DNA encoding the Glycine max GSTs GmGSTU2-2, GmGSTU4-4 and GmGSTU10-10. The parental GSTs are >88% identical at the sequence level; however, their specificity varies towards different substrates. The DNA library contained chimaeric structures of alternated segments of the parental sequences and point mutations. Chimaeric GST sequences were expressed in Escherichia coli and their enzymatic activities towards CDNB (1-chloro-2,4-dinitrobenzene) and the herbicide fluorodifen (4-nitrophenyl α,α,α-trifluoro-2-nitro-p-tolyl ether) were determined. A chimaeric clone (Sh14) with enhanced CDNB- and fluorodifen-detoxifying activities, and unusual co-operative kinetics towards CDNB and fluorodifen, but not towards GSH, was identified. The structure of Sh14 was determined at 1.75 Å (1 Å=0.1 nm) resolution in complex with S-(p-nitrobenzyl)-glutathione. Analysis of the Sh14 structure showed that a W114C point mutation is responsible for the altered kinetic properties. This was confirmed by the kinetic properties of the Sh14 C114W mutant. It is suggested that the replacement of the bulky tryptophan residue by a smaller amino acid (cysteine) results in conformational changes of the active-site cavity, leading to enhanced catalytic activity of Sh14. Moreover, the structural changes allow the strengthening of the two salt bridges between Glu(66) and Lys(104) at the dimer interface that triggers an allosteric effect and the communication between the hydrophobic sites.

  10. Natural Variants of the KPC-2 Carbapenemase have Evolved Increased Catalytic Efficiency for Ceftazidime Hydrolysis at the Cost of Enzyme Stability.

    Directory of Open Access Journals (Sweden)

    Shrenik C Mehta

    2015-06-01

    Full Text Available The spread of β-lactamases that hydrolyze penicillins, cephalosporins and carbapenems among Gram-negative bacteria has limited options for treating bacterial infections. Initially, Klebsiella pneumoniae carbapenemase-2 (KPC-2 emerged as a widespread carbapenem hydrolyzing β-lactamase that also hydrolyzes penicillins and cephalosporins but not cephamycins and ceftazidime. In recent years, single and double amino acid substitution variants of KPC-2 have emerged among clinical isolates that show increased resistance to ceftazidime. Because it confers multi-drug resistance, KPC β-lactamase is a threat to public health. In this study, the evolution of KPC-2 function was determined in nine clinically isolated variants by examining the effects of the substitutions on enzyme kinetic parameters, protein stability and antibiotic resistance profile. The results indicate that the amino acid substitutions associated with KPC-2 natural variants lead to increased catalytic efficiency for ceftazidime hydrolysis and a consequent increase in ceftazidime resistance. Single substitutions lead to modest increases in catalytic activity while the double mutants exhibit significantly increased ceftazidime hydrolysis and resistance levels. The P104R, V240G and H274Y substitutions in single and double mutant combinations lead to the largest increases in ceftazidime hydrolysis and resistance. Molecular modeling suggests that the P104R and H274Y mutations could facilitate ceftazidime hydrolysis through increased hydrogen bonding interactions with the substrate while the V240G substitution may enhance backbone flexibility so that larger substrates might be accommodated in the active site. Additionally, we observed a strong correlation between gain of catalytic function for ceftazidime hydrolysis and loss of enzyme stability, which is in agreement with the 'stability-function tradeoff' phenomenon. The high Tm of KPC-2 (66.5°C provides an evolutionary advantage as

  11. Ultrathin Co(Ni)-doped MoS2 nanosheets as catalytic promoters enabling efficient solar hydrogen production

    Institute of Scientific and Technical Information of China (English)

    Xiaoyan Ma; Jinquan Li; Changhua An; Juan Feng; Yuhua Chi; Junxue Liu; Jun Zhang

    2016-01-01

    The design of efficient artificial photosynthetic systems that harvest solar energy to drive the hydrogen evolution reaction via water reduction is of great importance from both the theoretical and practical viewpoints.Integrating appropriate co-catalyst promoters with strong light absorbing materials represents an ideal strategy to enhance the conversion efficiency of solar energy in hydrogen production.Herein,we report,for the first time,the synthesis of a class of unique hybrid structures consisting of ultrathin Co(Ni)-doped MoS2 nanosheets (co-catalyst promoter) intimately grown on semiconductor CdS nanorods (light absorber).The as-synthesized one-dimensional CdS@doped-MoS2 heterostructures exhibited very high photocatalytic activity (with a quantum yield of 17.3%) and stability towards H2 evolution from the photoreduction of water.Theoretical calculations revealed that Ni doping can increase the number of uncoordinated atoms at the edge sites of MoS2 nanosheets to promote electron transfer across the CdS/MoS2 interfaces as well as hydrogen reduction,leading to an efficient H2 evolution reaction.

  12. Pt-Doped NiFe₂O₄ Spinel as a Highly Efficient Catalyst for H₂ Selective Catalytic Reduction of NO at Room Temperature.

    Science.gov (United States)

    Sun, Wei; Qiao, Kai; Liu, Ji-Yuan; Cao, Li-Mei; Gong, Xue-Qing; Yang, Ji

    2016-04-11

    H2 selective catalytic reduction (H2-SCR) has been proposed as a promising technology for controlling NOx emission because hydrogen is clean and does not emit greenhouse gases. We demonstrate that Pt doped into a nickel ferrite spinel structure can afford a high catalytic activity of H2-SCR. A superior NO conversion of 96% can be achieved by employing a novel NiFe1.95Pt0.05O4 spinel-type catalyst at 60 °C. This novel catalyst is different from traditional H2-SCR catalysts, which focus on the role of metallic Pt species and neglect the effect of oxidized Pt states in the reduction of NO. The obtained Raman and XPS spectra indicate that Pt in the spinel lattice has different valence states with Pt(2+) occupying the tetrahedral sites and Pt(4+) residing in the octahedral ones. These oxidation states of Pt enhance the back-donation process, and the lack of filling electrons of the 5d band causes Pt to more readily hybridize with the 5σ orbital of the NO molecule, especially for octahedral Pt(4+), which enhances the NO chemisorption on the Pt sites. We also performed DFT calculations to confirm the enhancement of adsorption of NO onto Pt sites when doped into the Ni-Fe spinel structure. The prepared Pt/Ni-Fe catalysts indicate that increasing the dispersity of Pt on the surfaces of the individual Ni-Fe spinel-type catalysts can efficiently promote the H2-SCR activity. Our demonstration provides new insight into designing advanced catalysts for H2-SCR. PMID:26982816

  13. High efficiency chemical energy conversion system based on a methane catalytic decomposition reaction and two fuel cells: Part I. Process modeling and validation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Qinghua; Tian, Ye; Li, Hongjiao; Jia, Lijun; Xia, Chun; Li, Yongdan [Tianjin Key Laboratory of Catalysis Science and Technology and State Key Laboratory for Chemical Engineering (Tianjin University), School of Chemical Engineering, Tianjin University, Tianjin 300072 (China); Thompson, Levi T. [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109-2136 (United States)

    2010-10-01

    A highly efficient integrated energy conversion system is built based on a methane catalytic decomposition reactor (MCDR) together with a direct carbon fuel cell (DCFC) and an internal reforming solid oxide fuel cell (IRSOFC). In the MCDR, methane is decomposed to pure carbon and hydrogen. Carbon is used as the fuel of DCFC to generate power and produce pure carbon dioxide. The hydrogen and unconverted methane are used as the fuel in the IRSOFC. A gas turbine cycle is also used to produce more power output from the thermal energy generated in the IRSOFC. The output performance and efficiency of both the DCFC and IRSOFC are investigated and compared by development of exact models of them. It is found that this system has a unique loading flexibility due to the good high-loading property of DCFC and the good low loading property of IRSOFC. The effects of temperature, pressure, current densities, and methane conversion on the performance of the fuel cells and the system are discussed. The CO{sub 2} emission reduction is effective, up to 80%, can be reduced with the proposed system. (author)

  14. Designed copper-amine complex as an efficient template for one-pot synthesis of Cu-SSZ-13 zeolite with excellent activity for selective catalytic reduction of NOx by NH3.

    Science.gov (United States)

    Ren, Limin; Zhu, Longfeng; Yang, Chengguang; Chen, Yanmei; Sun, Qi; Zhang, Haiyan; Li, Caijin; Nawaz, Faisal; Meng, Xiangju; Xiao, Feng-Shou

    2011-09-21

    Low-cost copper-amine complex was rationally designed to be a novel template for one-pot synthesis of Cu-SSZ-13 zeolites. Proper confirmation and appropriate size make this complex fit well with CHA cages as an efficient template. The products exhibit superior catalytic performance on NH(3)-SCR reaction. PMID:21625721

  15. Direct synthesis of strong grating couplers for efficient integrated optical beam forming

    CERN Document Server

    Urošević, Stevan

    2014-01-01

    We describe a computational method for the direct synthesis of non-uniform optical grating coupler geometries on a photonic chip to form beams of arbitrary field distribution. The method is applied to grating couplers using high index contrast, typically encountered in silicon photonics for fiber-to-chip coupling and chip-based optical beam forming. We use a numerical synthesis approach to synthesize a non-uniform structure that emits a particular desired beam pattern, and explicitly take into account chirp generated by non-uniform gratings. Even for strong, short gratings, and for designs within the constraints of existing standard 45nm SOI-CMOS foundry process, mode overlaps exceeding 90% can be obtained. We discuss strengths and shortcomings of the approach and particular implementation. We demonstrate the method by synthesizing non-uniform grating coupler designs for efficient mode matching to optical fiber modes or single free-space beam modes with Gaussian magnitude and flat phase front and show that go...

  16. Iron plaque formed under aerobic conditions efficiently immobilizes arsenic in Lupinus albus L roots.

    Science.gov (United States)

    Fresno, Teresa; Peñalosa, Jesús M; Santner, Jakob; Puschenreiter, Markus; Prohaska, Thomas; Moreno-Jiménez, Eduardo

    2016-09-01

    Arsenic is a non-threshold carcinogenic metalloid. Thus, human exposure should be minimised, e.g. by chemically stabilizing As in soil. Since iron is a potential As immobiliser, it was investigated whether root iron plaque, formed under aerobic conditions, affects As uptake, metabolism and distribution in Lupinus albus plants. White lupin plants were cultivated in a continuously aerated hydroponic culture containing Fe/EDDHA or FeSO4 and exposed to arsenate (5 or 20 μM). Only FeSO4 induced surficial iron plaque in roots. LA-ICP-MS analysis accomplished on root sections corroborated the association of As to this surficial Fe. Additionally, As(V) was the predominant species in FeSO4-treated roots, suggesting less efficient As uptake in the presence of iron plaque. Fe/EDDHA-exposed roots neither showed such surficial FeAs co-localisation nor As(V) accumulation; in contrast As(III) was the predominant species in root tissue. Furthermore, FeSO4-treated plants showed reduced shoot-to-root As ratios, which were >10-fold lower compared to Fe/EDDHA treatment. Our results highlight the role of an iron plaque formed in roots of white lupin under aerobic conditions on As immobilisation. These findings, to our knowledge, have not been addressed before for this plant and have potential implications on soil remediation (phytostabilisation) and food security (minimising As in crops).

  17. Efficient Synthesis of Chiral Trisubstituted 1,2-Allenyl Ketones by Catalytic Asymmetric Conjugate Addition of Malonic Esters to Enynes.

    Science.gov (United States)

    Yao, Qian; Liao, Yuting; Lin, Lili; Lin, Xiaobin; Ji, Jie; Liu, Xiaohua; Feng, Xiaoming

    2016-01-26

    An N,N'-dioxide/scandium(III) complex catalyzed, highly efficient conjugate addition of malonic esters to enynes is described. A range of trisubstituted 1,2-allenyl ketones were obtained in high yields (up to 99 %) with good d.r. (up to 95/5) and excellent ee values (97 %-99 %). Moreover, the products could be easily transformed into chiral furan and 5-hydroxypyrazoline derivatives, both of which are important skeletons of many biologically active compounds and pharmacologicals. PMID:26694204

  18. Improvement of Catalytic Efficiency, Thermo-stability and Dye Decolorization Capability of Pleurotus ostreatus IBL-02 laccase by Hydrophobic Sol Gel Entrapment

    Directory of Open Access Journals (Sweden)

    Asgher Muhammad

    2012-09-01

    Full Text Available Abstract Background In serious consideration of the worldwide environmental issues associated with the extensive use of the textile dyes and effluents generated thereof, the scientists across the world are in search for potential treatment technologies for their treatment. In such scenario the ligninolytic enzymes provide a potential alternative because they are cost effective, eco-friendly and can be applied to wide range of dye containing industrial effluents. Results Laccase produced from Pleurotus ostreatus IBL-02 during decolorization of the reactive textile dye Drimarene brilliant red K-4BL (DBR K-4BL was purified and immobilized by hydrophobic gel entrapment. The crude laccase was 4.2-fold purified with specific activity of 573.52 U/mg after passing through the DEAE-Sepharose ion exchange and Sephadex-G-100 chromatography columns. P. ostreatus IBL-02 laccase was found to be a homogenous monomeric protein as evident by single band corresponding to 67 kDa on native and sodium dodesylsulfate polyacrylamide gel electrophoresis (PAGE. The laccase was immobilized by entrapment in Sol–gel matrix of trimethoxysilane (T and proplytetramethoxysilane (P prepared using different T:P molar ratios. The free and immobilized laccases were compared to investigate the effect of immobilization on catalytic efficiency and thermo-stability features. Laccase immobilized in the Sol–gel of 1:5 T:P ratio was optimally active and thermo-stable fraction at pH 5, 60°C with half-life of 3 h and 50 min. Laccases immobilized in 1:2 and 1:5 T:P ratio gels had significantly higher Km (83 and100mM and Vmax (1000 and 1111 mM/mg values as compared to free laccase. After 5 h reaction time varying decolorization percentages with a maximum of 100% were achieved for different dyes and effluents. Conclusions In summary, P. ostreatus IBL-02 laccase was immobilized by entrapping in a Sol–gel matrix with an objective to enhance its catalytic and stability properties. Sol

  19. Efficiency of different sanitation methods on Listeria monocytogenes biofilms formed under various environmental conditions.

    Science.gov (United States)

    Belessi, Charalambia-Eirini A; Gounadaki, Antonia S; Psomas, Antonios N; Skandamis, Panagiotis N

    2011-03-01

    The resistance of Listeria monocytogenes biofilms formed under food processing conditions, against various sanitizing agents and disinfection procedures was evaluated in the present study. The first sanitation procedure included biofilm formation on stainless steel coupons (SS) placed in tryptic soy broth supplemented with 0.6% yeast extract (TSBYE) of various concentrations of NaCl (0.5, 7.5 and 9.5%) at different temperatures (5 and 20 °C). The biofilms formed were exposed to warm (60 °C) water for 20 min, or to peroxyacetic acid (2% PAA) for 1, 2, 3 and 6 min. Treatment with warm water caused no significant (P ≥ 0.05) reductions in the attached populations. Conversely, surviving bacteria on SS coupons decreased as the exposure time to 2% PAA increased and could not be detected by culture after 6 min of exposure. Biofilms formed at 20°C were more resistant to PAA than biofilms formed at 5 °C. Salt concentration in the growth medium had no marked impact on the resistance to PAA. The second sanitation procedure included biofilm formation of nonadapted (NA) and acid-adapted (AA) cells in TSBYE of pH 5.0 and 7.0 (i.e., NA-5.0, NA-7.0 and AA-5.0, AA-7.0) at 4 °C. Coupons bearing attached cells of L. monocytogenes were periodically exposed to chlorine (0.465% Cl(-)), quaternary ammonium compound (1% QAC) and 2% PAA. The resistance of attached cells to QAC, PAA and Cl(-) followed the order: AA-5.0>NA-7.0 ≥ AA-7.0>NA-5.0. The most effective sanitizer was QAC followed by PAA and Cl(-). The results can lead to the development of efficient sanitation strategies in order to eliminate L. monocytogenes from the processing environment. Furthermore, such results may explain the presence of L. monocytogenes after sanitation as a result of cell attachment history. PMID:21093085

  20. [Effect of natural organic matter on coagulation efficiency and characterization of the flocs formed].

    Science.gov (United States)

    Xu, Lei; Yu, Wen-Zheng; Liang, Liang; Wang, Tong

    2013-11-01

    Coagulation is an efficient way to remove the natural organic matter in water. Our works primarily focused on the effect of natural organic matter on coagulation and the properties of the flocs formed. PACl25 was used as the coagulant in this research to simulate the process of coagulation, and typical substance of NOM, humic acid and citric acid were used to prepare the model water. The impact of NOM on the size, fractal dimension, Zeta potential of the flocs and residual aluminum in solution was explored. The experiment results showed that as the concentration of humic acid and citric acid increased in the experimental range, the size and growth velocity of flocs, Zeta potential and fractal dimension showed a tendency of decrease (when the concentration of humic acid increased from 0 mg x L(-1) to 10 mg x L(-1), citric acid increased from 0 micromol x L(-1) to 7 micromol x L(-1), the size of flocs before breakage was decreased by 34.2% and 53.1%, respectively, the Zeta potential decreased from about 10 mV to approximately -10 mV and -2.5 mV, the growth velocity of the flocs was decreased by 42.6% and 77.5%, and the fractal dimension declined by 0.08 and 0.094), which showed the occupying of the floc surface by NOM resulted in the decrease of its activity and compactivity. However, the residual aluminum was not affected by the decrease of coagulation efficiency.

  1. Mutant form C115H of Clostridium sporogenes methionine γ-lyase efficiently cleaves S-Alk(en)yl-l-cysteine sulfoxides to antibacterial thiosulfinates.

    Science.gov (United States)

    Kulikova, Vitalia V; Anufrieva, Natalya V; Revtovich, Svetlana V; Chernov, Alexander S; Telegin, Georgii B; Morozova, Elena A; Demidkina, Tatyana V

    2016-10-01

    Pyridoxal 5'-phosphate-dependent methionine γ-lyase (MGL) catalyzes the β-elimination reaction of S-alk(en)yl-l-cysteine sulfoxides to thiosulfinates, which possess antimicrobial activity. Partial inactivation of the enzyme in the course of the reaction occurs due to oxidation of active site cysteine 115 conserved in bacterial MGLs. In this work, the C115H mutant form of Clostridium sporogenes MGL was prepared and the steady-state kinetic parameters of the enzyme were determined. The substitution results in an increase in the catalytic efficiency of the mutant form towards S-substituted l-cysteine sulfoxides compared to the wild type enzyme. We used a sulfoxide/enzyme system to generate antibacterial activity in situ. Two-component systems composed of the mutant enzyme and three S-substituted l-cysteine sulfoxides were demonstrated to be effective against Gram-positive and Gram-negative bacteria and three clinical isolates from mice. © 2016 IUBMB Life, 68(10):830-835, 2016.

  2. Facile synthesis of unique NiO nanostructures for efficiently catalytic conversion of CH4 at low temperature

    Science.gov (United States)

    Ye, Yucheng; Zhao, Yanting; Ni, Liuliu; Jiang, Kedan; Tong, Guoxiu; Zhao, Yuling; Teng, Botao

    2016-01-01

    A simple one-pot thermal decomposition approach to the selective synthesis of NiO nanomaterials was developed. The morphologies of the NiO nanomaterials were nanoparticle-based sheets, octahedra, nanosheet-built agglomerates, and nanoparticle-based microspheres. The samples were characterized by field-emission scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and N2 adsorption analyses. The morphology, crystal size, and texture properties of the products can be easily modulated by selecting various decomposition temperatures and precursors. Samples with high specific surface area and small crystal size were found to easily form at low sintering temperatures and when basic nickel carbonate and nickel oxalate dihydrate were used as precursors. Reduction property and CH4 conversion, as functions of decomposition temperature and precursor type, were systematically investigated. When NiCO3·2Ni(OH)2·4H2O and NiC2O4·2H2O were used as precursors, the as-obtained nanosheet-built agglomerates and nanoparticle-based sheets presented a high CH4 conversion rate because of the small crystal size and large specific surface area.

  3. Efficient Robust Optimization of Metal Forming Processes using a Sequential Metamodel Based Strategy

    Science.gov (United States)

    Wiebenga, J. H.; Klaseboer, G.; van den Boogaard, A. H.

    2011-08-01

    The coupling of Finite Element (FE) simulations to mathematical optimization techniques has contributed significantly to product improvements and cost reductions in the metal forming industries. The next challenge is to bridge the gap between deterministic optimization techniques and the industrial need for robustness. This paper introduces a new and generally applicable structured methodology for modeling and solving robust optimization problems. Stochastic design variables or noise variables are taken into account explicitly in the optimization procedure. The metamodel-based strategy is combined with a sequential improvement algorithm to efficiently increase the accuracy of the objective function prediction. This is only done at regions of interest containing the optimal robust design. Application of the methodology to an industrial V-bending process resulted in valuable process insights and an improved robust process design. Moreover, a significant improvement of the robustness (>2σ) was obtained by minimizing the deteriorating effects of several noise variables. The robust optimization results demonstrate the general applicability of the robust optimization strategy and underline the importance of including uncertainty and robustness explicitly in the numerical optimization procedure.

  4. The Star Formation Efficiency in Nearby Galaxies: Measuring Where Gas Forms Stars Effectively

    CERN Document Server

    Leroy, Adam K; Brinks, Elias; Bigiel, Frank; De Blok, W J G; Madore, Barry; Thornley, M D

    2008-01-01

    We measure the star formation efficiency (SFE), the star formation rate per unit gas, in 23 nearby galaxies and compare it to expectations from proposed star formation laws and thresholds. We use HI maps from THINGS and derive H2 maps from HERACLES and BIMA SONG CO. We estimate the star formation rate by combining GALEX FUV maps and SINGS 24 micron maps, infer stellar surface density profiles from SINGS 3.6 micron data, and use kinematics from THINGS. We measure the SFE as a function of: the free-fall and orbital timescales; midplane gas pressure; stability of the gas disk to collapse (including the effects of stars); the ability of perturbations to grow despite shear; and the ability of a cold phase to form. In spirals, the SFE of H2 alone is nearly constant at 5.25 +/- 2.5 x 10^(-10) yr^(-1) (equivalent to an H2 depletion time of 1.9x10^9 yr) as a function of all of these variables at our 800 pc resolution. Where the ISM is mostly HI, on the other hand, the SFE decreases with increasing radius in both spira...

  5. Raspberry Pi- A Small, Powerful, Cost Effective and Efficient Form Factor Computer: A Review

    Directory of Open Access Journals (Sweden)

    Anand Nayyar

    2015-12-01

    Full Text Available Raspberry Pi, an efficient and cost effective credit card sized computer comes under light of sun by United Kingdom-Raspberry Pi foundation with the aim to enlighten and empower computer science teaching in schools and other developing countries. Since its inception, various open source communities have contributed tons towards open source apps, operating systems and various other small form factor computers similar to Raspberry Pi. Till date, researchers, hobbyists and other embedded systems enthusiast across the planet are making amazing projects using Pi which looks unbelievable and have out-of-the-box implementation. Raspberry Pi since its launch is regularly under constant development cum improvement both in terms of hardware and software which in-turn making Pi a “Full Fledged Computer” with possibility to be considered for almost all computing intensive tasks. The aim of this research paper is to enlighten regarding what is Raspberry Pi, Why Raspberry Pi is Required, Generations of Raspberry Pi, operating systems available till date in Pi and other hardware available for project development. This paper will lay foundation for various open source communities across planet to become aware and use this credit card sized computer for making projects ranging from day to day activities to scientific and complex applications development.

  6. EVALUATION OF THE EFFICIENCY OF PHYTOTHERAPY WITH MASTODINONE AND GELARIUM IN PATIENTS WITH DIFFUSE FORMS OF MASTOPATHIES

    OpenAIRE

    N. I. Rozhkova; Ye. V. Meskikh

    2014-01-01

    The authors define mastopathies and consider the major forms of this disease. They also present the results of the clinical trials eval- uating the efficiency of the herbal drugs mastodinone and gelarium in different forms of diffuse mastopathies, accompanied by the pain syndrome of varying degree, and depression.

  7. Radiolytic Synthesis of Pt-Ru Catalysts Based on Functional Polymer-Grafted MWNT and Their Catalytic Efficiency for CO and MeOH

    Directory of Open Access Journals (Sweden)

    Dae-Soo Yang

    2011-01-01

    Full Text Available Pt-Ru catalysts based on functional polymer-grafted MWNT (Pt-Ru@FP-MWNT were prepared by radiolytic deposition of Pt-Ru nanoparticles on functional polymer-grafted multiwalled carbon nanotube (FP-MWNT. Three different types of functional polymers, poly(acrylic acid (PAAc, poly(methacrylic acid (PMAc, and poly(vinylphenyl boronic acid (PVPBAc, were grafted on the MWNT surface by radiation-induced graft polymerization (RIGP. Then, Pt-Ru nanoparticles were deposited onto the FP-MWNT supports by the reduction of metal ions using γ-irradiation to obtain Pt-Ru@FP-MWNT catalysts. The Pt-Ru@FP-MWNT catalysts were then characterized by XRD, XPS, TEM ,and elemental analysis. The catalytic efficiency of Pt-Ru@FP-MWNT catalyst was examined for CO stripping and MeOH oxidation for use in a direct methanol fuel cell (DMFC. The Pt-Ru@PVPBAc-MWNT catalyst shows enhanced activity for electro-oxidation of CO and MeOH oxidation over that of the commercial E-TEK catalyst.

  8. Catalytic Conversion of Biofuels

    DEFF Research Database (Denmark)

    Jørgensen, Betina

    This thesis describes the catalytic conversion of bioethanol into higher value chemicals. The motivation has been the unavoidable coming depletion of the fossil resources. The thesis is focused on two ways of utilising ethanol; the steam reforming of ethanol to form hydrogen and the partial oxida...

  9. Oxidation of phosphine by sulfur or selenium involving a catalytic cycle in the interconversion of monomer and tetramer forms of copper-maleonitriledithiolate complexes

    Indian Academy of Sciences (India)

    Biplab K Maiti; Sabyasachi Sarkar

    2009-01-01

    The addition of triphenylphosphine (PPh3), into [Et4N]4[Cu4(mnt)4] shifted its characteristic electronic spectral band at 377 nm to 372 nm which is identical to that of the monomeric species, [Et4N][Cu(mnt)(PPh3)]. This reaction was followed by electrochemical study and also by 31P NMR spectroscopy. Such interconversion with the participation of breaking of bridging copper-3-sulfur bond with the formation of new copper-phosphorous bond led to the development of a catalytic cycle using excess PPh3 and S or Se as the reacting substrates. The turnover number for the oxidation of PPh3 by S was found to be 0.8 × 10-2 s-1 and that with Se was $0.6 × 10-2 s-1 using this catalytic system.

  10. The progress of catalytic technologies in water purification:a review

    Institute of Scientific and Technical Information of China (English)

    LI Dapeng; QU Jiuhui

    2009-01-01

    Catalytic technologies have been paid increasing attention in refractory pollutants abatement due to its practical and potential values in water purification.As effective and efficient approaches for water purification,Fenton's reagent,ozonation,electrochemical and photocatalytic methods have been widely studied and applied in different aspects and have been reviewed by several papers.In recent years,some novel catalytic processes based on above processes have been developed for enhancing the efficiency of removing the organics form water.This reviews emphasize on the recent development of heterogeneous catalytic ozonation,electrocatalysis in respect of novel electrodes and electro-Fenton method (EF),photoelectrocatalysis process (PEC) and photoelectron-Fenton (PEF) in water purification.It is also an attempt to propose general ideas about mechanism and principle enhancing the catalytic efficiency for degradation and mineralization of organics in water.

  11. Managerial form, ownership and efficiency: a case-study of Argentine agriculture

    OpenAIRE

    Gallacher, Marcos; Goetz, Stephan J.; Debertin, David L.

    1994-01-01

    In agriculture, studies dealing with the separation of ownership from control have focused on sharecropping, paying little attention to the impact of management and ownership on efficiency. Using Argentine data, this study tests the hypothesis that efficiency is a function of type of management, concentration of ownership, and mechanisms for monitoring managers. Results show that management, ownership and monitoring have a greater impact on marketing efficiency than either on technical or cos...

  12. The Effect of Governance Forms on North American Airport Efficiency: A Comparative Analysis of Airport Authority vs. Government Branch

    OpenAIRE

    Zhao, Qi; Choo, Yap Y.; Oum, Tae H.

    2014-01-01

    This paper applies a stochastic cost frontier model to a panel of 54 major airports over 2002-2008 to examine how the two dominant governance forms of publicly owned airports in the United States and Canada, namely, operation and governance by a government (city, county, or state) branch, or by an airport authority, affect airport efficiency performance. Our key findings are (a) airports operated by an airport authority achieve higher cost efficiency (on average, 14% higher technical efficien...

  13. Unsteady catalytic processes and sorption-catalytic technologies

    International Nuclear Information System (INIS)

    Catalytic processes that occur under conditions of the targeted unsteady state of the catalyst are considered. The highest efficiency of catalytic processes was found to be ensured by a controlled combination of thermal non-stationarity and unsteady composition of the catalyst surface. The processes based on this principle are analysed, in particular, catalytic selective reduction of nitrogen oxides, deep oxidation of volatile organic impurities, production of sulfur by the Claus process and by hydrogen sulfide decomposition, oxidation of sulfur dioxide, methane steam reforming and anaerobic combustion, selective oxidation of hydrocarbons, etc.

  14. Unsteady catalytic processes and sorption-catalytic technologies

    Energy Technology Data Exchange (ETDEWEB)

    Zagoruiko, A N [G.K. Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2007-07-31

    Catalytic processes that occur under conditions of the targeted unsteady state of the catalyst are considered. The highest efficiency of catalytic processes was found to be ensured by a controlled combination of thermal non-stationarity and unsteady composition of the catalyst surface. The processes based on this principle are analysed, in particular, catalytic selective reduction of nitrogen oxides, deep oxidation of volatile organic impurities, production of sulfur by the Claus process and by hydrogen sulfide decomposition, oxidation of sulfur dioxide, methane steam reforming and anaerobic combustion, selective oxidation of hydrocarbons, etc.

  15. Efficient linear algebra routines for symmetric matrices stored in packed form.

    Science.gov (United States)

    Ahlrichs, Reinhart; Tsereteli, Kakha

    2002-01-30

    Quantum chemistry methods require various linear algebra routines for symmetric matrices, for example, diagonalization or Cholesky decomposition for positive matrices. We present a small set of these basic routines that are efficient and minimize memory requirements.

  16. Efficiency of procedures for induction and cultivation of Pseudomonas syringae pv. pisi L-form

    NARCIS (Netherlands)

    Elvira-Recuenco, M.; Vuurde, van J.W.L.

    2003-01-01

    The L-form of Pseudomonas syringae pv. phaseolicola has been proved to induce resistance to bean halo blight.Various procedures were tested to induce the L-form of Pseudomonas syringae pv. pisi for its potential use as biocontrol agent of pea bacterial blight. Cell-wall deficient cells were induced

  17. A simple two step procedure for purification of the catalytic domain of chicken tryptophan hydroxylase 1 in a form suitable for crystallization

    DEFF Research Database (Denmark)

    Windahl, Michael Skovbo; Petersen, Charlotte R.; Munch, Astrid;

    2008-01-01

    Tryptophan hydroxylase (TPH) [EC 1.14.16.4] catalyzes the conversion of tryptophan to 5-hydroxytryptophan, which is the first and rate-determining step in the biosynthesis of the neurotransmitter serotonin. We have expressed the catalytic domain of chicken (Gallus gallus) TPH isoform 1 in Escheri......Tryptophan hydroxylase (TPH) [EC 1.14.16.4] catalyzes the conversion of tryptophan to 5-hydroxytryptophan, which is the first and rate-determining step in the biosynthesis of the neurotransmitter serotonin. We have expressed the catalytic domain of chicken (Gallus gallus) TPH isoform 1...... in Escherichia coli in high yield. The enzyme was highly purified using only one anion exchange and one gel filtration, with a yield of 11 mg/L culture and a specific activity of 0.60 μmol/min/mg. The Km values were determined to Km,tryptophan = 7.7 ± 0.7 μM, Km,BH4=324±10 μM and Km,O2=39±2 μM. Substrate...... inhibition by tryptophan was observed at concentrations above 15 μM. Furthermore, the purified enzyme has been crystallized without 7,8-dihydro-l-biopterin and a data set to 3 Å resolution has been collected....

  18. Hurst exponent and prediction based on weak-form efficient market hypothesis of stock markets

    Science.gov (United States)

    Eom, Cheoljun; Choi, Sunghoon; Oh, Gabjin; Jung, Woo-Sung

    2008-07-01

    We empirically investigated the relationships between the degree of efficiency and the predictability in financial time-series data. The Hurst exponent was used as the measurement of the degree of efficiency, and the hit rate calculated from the nearest-neighbor prediction method was used for the prediction of the directions of future price changes. We used 60 market indexes of various countries. We empirically discovered that the relationship between the degree of efficiency (the Hurst exponent) and the predictability (the hit rate) is strongly positive. That is, a market index with a higher Hurst exponent tends to have a higher hit rate. These results suggested that the Hurst exponent is useful for predicting future price changes. Furthermore, we also discovered that the Hurst exponent and the hit rate are useful as standards that can distinguish emerging capital markets from mature capital markets.

  19. Efficient Robust Optimization of Metal Forming Processes using a Sequential Metamodel Based Strategy

    NARCIS (Netherlands)

    Wiebenga, J.H.; Klaseboer, G.; Boogaard, van den A.H.; Chung, J.

    2011-01-01

    The coupling of Finite Element (FE) simulations to mathematical optimization techniques has contributed significantly to product improvements and cost reductions in the metal forming industries. The next challenge is to bridge the gap between deterministic optimization techniques and the industrial

  20. Joint Ventures – An Alternative and Efficient Form of Economic Organisation

    OpenAIRE

    Manea Ioana Livia; Popa Ioana-Anda

    2010-01-01

    The joint ventures are now a quite often used form of organization for some economic activities, which make them mutually beneficial. They are based on the joint venture contract. This form of organization does not require registration and association formalities, detemines no new legal person, being a flexible contract, negotiated and agreed by the parts of the contract. These parts (individuals / entities) may estabish any kind of rules to determine their mutual rights and obligations. The ...

  1. Test of Weak Form Efficiency: An Empirical Study of the Malaysian Foreign Exchange Market

    OpenAIRE

    Lim, Pei Mun

    2011-01-01

    This paper empirically tests the Efficient Market Hypothesis (EMH) in the weak sense for the Malaysian foreign exchange market. The hypothesis is tested using two ways. First is by testing the random walk hypothesis based on individual unit root test and second is by testing the profitability of simple technical trading rules. The study covers the high frequency daily data from January 1997 to December 2010 and the spot exchange rates are quoted as Malaysian Ringgit per unit of US Dollar. Due...

  2. Ionization Efficiency of Doubly Charged Ions Formed from Polyprotic Acids in Electrospray Negative Mode

    Science.gov (United States)

    Liigand, Piia; Kaupmees, Karl; Kruve, Anneli

    2016-07-01

    The ability of polyprotic acids to give doubly charged ions in negative mode electrospray was studied and related to physicochemical properties of the acids via linear discriminant analysis (LDA). It was discovered that the compound has to be strongly acidic (low p K a1 and p K a2) and to have high hydrophobicity (log P ow) to become multiply charged. Ability to give multiply charged ions in ESI/MS cannot be directly predicted from the solution phase acidities. Therefore, for the first time, a quantitative model to predict the charge state of the analyte in ESI/MS is proposed and validated for small anions. Also, a model to predict ionization efficiencies of these analytes was developed. Results indicate that acidity of the analyte, its octanol-water partition coefficient, and charge delocalization are important factors that influence ionization efficiencies as well as charge states of the analytes. The pH of the solvent was also found to be an important factor influencing the ionization efficiency of doubly charged ions.

  3. Synthesis of manganese incorporated hierarchical mesoporous silica nanosphere with fibrous morphology by facile one-pot approach for efficient catalytic ozonation.

    Science.gov (United States)

    Afzal, Shahzad; Quan, Xie; Chen, Shuo; Wang, Jing; Muhammad, Dost

    2016-11-15

    Manganese incorporated fibrous silica nanosphere (MnOx-0.013/KCC-1) was synthesized by one step hydrothermal method for the first time and its catalytic activity for ozonation of oxalic acid was studied. For comparison, manganese loaded MCM-41 (MnOx-0.013/MCM-41) was prepared by impregnation method. Various characterizations showed that the morphological, structural and textural properties of MnOx-0.013/KCC-1 were well preserved. Ozonation and catalytic ozonation by MnOx-0.013/KCC-1 and MnOx-0.013/MCM-41 led to 4, 85 and 60% reduction in TOC respectively. Furthermore, 0.05 and 1.2mgL(-1) leaching of Mn was detected from MnOx-0.013/KCC-1 and MnOx-0.013/MCM-41, which are approximately 2.0 and 42.0% of the total Mn present in MnOx-0.013/KCC-1 and MnOx-0.013/MCM-41 respectively. The high catalytic activity was attributed to the generation of hydroxyl radical. Surface hydroxyl groups investigated by using phosphates and ATR-FTIR were believed to be the active sites. Our proposed method of synthesis can be generalized for the synthesis of other metal oxides incorporated fibrous silica for environmental catalysis and other catalytic reactions. PMID:27434734

  4. Catalytic Combustion of Gasified Waste

    Energy Technology Data Exchange (ETDEWEB)

    Kusar, Henrik

    2003-09-01

    This thesis concerns catalytic combustion for gas turbine application using a low heating-value (LHV) gas, derived from gasified waste. The main research in catalytic combustion focuses on methane as fuel, but an increasing interest is directed towards catalytic combustion of LHV fuels. This thesis shows that it is possible to catalytically combust a LHV gas and to oxidize fuel-bound nitrogen (NH{sub 3}) directly into N{sub 2} without forming NO{sub x} The first part of the thesis gives a background to the system. It defines waste, shortly describes gasification and more thoroughly catalytic combustion. The second part of the present thesis, paper I, concerns the development and testing of potential catalysts for catalytic combustion of LHV gases. The objective of this work was to investigate the possibility to use a stable metal oxide instead of noble metals as ignition catalyst and at the same time reduce the formation of NO{sub x} In paper II pilot-scale tests were carried out to prove the potential of catalytic combustion using real gasified waste and to compare with the results obtained in laboratory scale using a synthetic gas simulating gasified waste. In paper III, selective catalytic oxidation for decreasing the NO{sub x} formation from fuel-bound nitrogen was examined using two different approaches: fuel-lean and fuel-rich conditions. Finally, the last part of the thesis deals with deactivation of catalysts. The various deactivation processes which may affect high-temperature catalytic combustion are reviewed in paper IV. In paper V the poisoning effect of low amounts of sulfur was studied; various metal oxides as well as supported palladium and platinum catalysts were used as catalysts for combustion of a synthetic gas. In conclusion, with the results obtained in this thesis it would be possible to compose a working catalytic system for gas turbine application using a LHV gas.

  5. Improvement of quantum efficiency using surface texture of solar cell in the form of pyramid

    International Nuclear Information System (INIS)

    The work presented in this paper concerns a detailed study about the light transmission through textured surfaces in a surface made up of pyramids [1, 2]. We investigate to what extent and under what conditions we want to take advantage of ray incidence five times and more [3, 4]. It is found that these analyses can be used to determine the optimal surface texture, which provides the best light trapping for solar cells in terms of the total internal reflection occurring in the high-index medium at incidence angles larger than the nominal critical angle [5-11]. One of the main contributions of this paper is the analysis and quantification of the influence of the opening between the heads of the two closest pyramids in textured surface for solar cells and its application to the photovoltaic parameters, such as the quantum efficiency. In this model, we show that the material can have five and more successive incident ray absorptions instead of three currently, where we changed the direction of the reflected ray, by varying the angle between the two neighbouring pyramids, the incidence angle, the opening between the heads of the two closest pyramids and their height. Thus, an angle between the two neighbouring pyramids varies between 20 and 12° and an angle of incidence varies between 80 and 84°. For these values of the angle between the two neighbouring pyramids and incidence angle, the opening between the heads of the two closest pyramids varied respectively from 3.53 to 2.10 μm for a pyramid height of 10 μm. This leads to a substantial increase of the quantum efficiency, thus the photovoltaic efficiency

  6. Forming high efficiency silicon solar cells using density-graded anti-reflection surfaces

    Science.gov (United States)

    Yuan, Hao-Chih; Branz, Howard M.; Page, Matthew R.

    2014-09-09

    A method (50) is provided for processing a graded-density AR silicon surface (14) to provide effective surface passivation. The method (50) includes positioning a substrate or wafer (12) with a silicon surface (14) in a reaction or processing chamber (42). The silicon surface (14) has been processed (52) to be an AR surface with a density gradient or region of black silicon. The method (50) continues with heating (54) the chamber (42) to a high temperature for both doping and surface passivation. The method (50) includes forming (58), with a dopant-containing precursor in contact with the silicon surface (14) of the substrate (12), an emitter junction (16) proximate to the silicon surface (14) by doping the substrate (12). The method (50) further includes, while the chamber is maintained at the high or raised temperature, forming (62) a passivation layer (19) on the graded-density silicon anti-reflection surface (14).

  7. The Precise and Efficient Identification of Medical Order Forms Using Shape Trees

    Science.gov (United States)

    Henker, Uwe; Petersohn, Uwe; Ultsch, Alfred

    A powerful and flexible technique to identify, classify and process documents using images from a scanning process is presented. The types of documents can be described to the system as a set of differentiating features in a case base using shape trees. The features are filtered and abstracted from an extremely reduced scanner image of the document. Classification rules are stored with the cases to enable precise recognition and further mark reading and Optical Character Recognition (OCR) process. The method is implemented in a system which actually processes the majority of requests for medical lab procedures in Germany. A large practical experiment with data from practitioners was performed. An average of 97% of the forms were correctly identified; none were identified incorrectly. This meets the quality requirements for most medical applications. The modular description of the recognition process allows for a flexible adaptation of future changes to the form and content of the document’s structures.

  8. After the interaction: an efficiently star-forming molecular disk in NGC5195

    CERN Document Server

    Alatalo, Katherine; Nyland, Kristina; Aalto, Susanne; Bitsakis, Theodoros; Gallagher, John S; Lanz, Lauranne

    2016-01-01

    We present new molecular gas maps of NGC5195 (alternatively known as M51b) from the Combined Array for Research in Millimeter Astronomy (CARMA), including 12CO(1-0), 13CO(1-0), CN(1-0), and CS(2-1). NGC5195 has also been detected in 3mm continuum. NGC5195 has a 12CO/13CO ratio consistent with normal star-forming galaxies. The CN(1-0) intensity is higher than is seen in an average star-forming galaxy, possibly enhanced in the diffuse photo-dissociation regions. Stellar template fitting of the nuclear spectrum of NGC5195 shows two stellar populations: an 80% mass fraction of old (>10Gyr) and a 20% mass fraction of intermediate-aged (~1Gyr) stellar populations, providing a constraint on the timescale over which NGC5195 experienced enhanced star formation during its interaction with M51a. The average molecular gas depletion timescale in NGC5195 is: tdep=3.08Gyr, a factor of ~2 larger than the depletion timescales in nearby star-forming galaxies, but consistent with the depletion seen in CO-detected early-type gal...

  9. EFFICIENCY OF FORMING NUCLEUS COLONIES IN ORDER TO DECREASE POPULATION OF Varroa destructor (ANDRESON AND TRUEMAN, 2000 IN BEEHIVES

    Directory of Open Access Journals (Sweden)

    Zlatko Puškadija

    2003-12-01

    Full Text Available Forming of nucleus colonies is efficient method in growth control of Varroa destructor population. Its goal is to decrease parasite’s pressure on bee colony. The advantage of this bio-technical measurement lays in its implement during vegetation season which delays use of the chemical resources for Varroa destructor control population in beehives for the post major honey harvest period. Nucleus colonies were formed from approx. half of sealed brood (35.5 ± 5.8 dm² and average of 5915 ± 912 bees. Results showed that there were 37.2 ± 5.6% mites removed from parental colonies. Minimum was 30.8%, and maximum was 45.5%. Due to such relatively small efficiency, this method cannot be recommended as unique, but it can be effective if it is applied in the post spring's honey harvest period as a part of growth reduction strategy of Varroa destructor population in beehive.

  10. Test of The Weak Form Efficient Market Hypothesis for The Istanbul Stock Exchange By Markov Chains Methodology

    OpenAIRE

    KILIÇ, Öğr. Gör. Dr. Süleyman Bilgin

    2013-01-01

    In this study Markov chain methodology is used to test whether or not the daily returns of the Istanbul Stock Exchange ISE 100 index follows a martingale random walk process If the Weak Form Efficient Market Hypothesis EMH holds in any stock market stocks prices or returns follow a random walk process The random walk theory asserts that price movements will not follow any patterns or trends and that past price movements cannot be used to predict future price movements hence technic...

  11. Enhanced Internal Quantum Efficiency and Light Extraction Efficiency of Light-emitting Diodes with Air-gap Photonic Crystal Structure Formed by Tungsten Nano-mask

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Chuyoung; Hong, Sanghyun; Jung, Gunyoung; Park, Seongju [Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of); Kim, Ki Seok [Samsung Electronics Co. Ltd., Suwon (Korea, Republic of)

    2014-03-15

    We demonstrate the blue InGaN/GaN multiple quantum wells light-emitting diodes (LEDs) with an embedded air-gap photonic crystal (PC) which was fabricated by the lateral epitaxial overgrowth of GaN layer on the tungsten (W) nano-masks. The periodic air-gap PC was formed by the chemical reaction of hydrogen with GaN on the W nano-mask. The optical output power of LEDs with an air-gap PC was increased by 26% compared to LEDs without an air-gap PC. The enhanced optical output power was attributed to the improvement in internal quantum efficiency and light extraction efficiency by the air-gap PC embedded in GaN layer.

  12. Catalytic thermal barrier coatings

    Science.gov (United States)

    Kulkarni, Anand A.; Campbell, Christian X.; Subramanian, Ramesh

    2009-06-02

    A catalyst element (30) for high temperature applications such as a gas turbine engine. The catalyst element includes a metal substrate such as a tube (32) having a layer of ceramic thermal barrier coating material (34) disposed on the substrate for thermally insulating the metal substrate from a high temperature fuel/air mixture. The ceramic thermal barrier coating material is formed of a crystal structure populated with base elements but with selected sites of the crystal structure being populated by substitute ions selected to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a higher rate than would the base compound without the ionic substitutions. Precious metal crystallites may be disposed within the crystal structure to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a lower light-off temperature than would the ceramic thermal barrier coating material without the precious metal crystallites.

  13. Estimating the temperature of a catalytic converter

    Energy Technology Data Exchange (ETDEWEB)

    Ma, T.T.-H.

    1994-11-02

    A method is described for estimating the temperature in a catalytic converter used in the exhaust system of an internal combustion engine. Pressure sensors monitor the flow resistance across the catalytic converter to provide an indication of the temperature inside. This feedback system allows heating devices to be switched off and thus avoid overheating, while maintaining the catalytic converter's efficiency by assuring that it does not operate below its light off temperature. (UK)

  14. Characterization of the efficiency of the gas-solid contact in circulating bed at by the use of a test reaction: the cumene catalytic cracking

    Energy Technology Data Exchange (ETDEWEB)

    Bayle, J.; Gauthier, T.; Pontier, R. [Institut Francais du Petrole (IFP), 92 - Rueil-Malmaison (France); Briens, C.L.; Bergougnou, M. [University of Western Ontario, London, ON (Canada). Dept. of Physics

    1995-12-31

    The gas-solid down with the stream reactor, the ``downer``, presents a main interest for the high-speed reactions because it is well adapted to hard conditions uses: very short residence times, high temperatures and feeds of catalyst. This reactor type already presents a certain advantage to estimate the charges or new catalysts potential. But, it particularly constitutes an interesting option for some processes as petroleum cuts catalytic cracking. In order to intensify the contact between the catalyst and the reagents, the temperature increase of the reagents has to be almost instantaneous and the initial contact between the gas and the solid particles particularly effective. So as to validate these two hypothesis, the test reaction of the cumene catalytic cracking is carried out in the pilot unit ``downer`` of the Western Ontario University. (O.M.). 11 refs., 3 figs.

  15. Efficient Diethylzinc/Gallic Acid and Diethylzinc/Gallic Acid Ester Catalytic Systems for the Ring-Opening Polymerization of rac-Lactide

    Directory of Open Access Journals (Sweden)

    Karolina Żółtowska

    2015-12-01

    Full Text Available Polylactide (PLA represents one of the most promising biomedical polymers due to its biodegradability, bioresorbability and good biocompatibility. This work highlights the synthesis and characterization of PLAs using novel diethylzinc/gallic acid (ZnEt2/GAc and diethylzinc/propyl gallate (ZnEt2/PGAc catalytic systems that are safe for human body. The results of the ring-opening polymerization (ROP of rac-lactide (rac-LA in the presence of zinc-based catalytic systems have shown that, depending on the reaction conditions, “predominantly isotactic”, disyndiotactic or atactic PLA can be obtained. Therefore, the controlled and stereoselective ROP of rac-LA is discussed in detail in this paper.

  16. The Fabrication of Ga2O3/ZSM-5 Hollow Fibers for Efficient Catalytic Conversion of n-Butane into Light Olefins and Aromatics

    Directory of Open Access Journals (Sweden)

    Jing Han

    2016-01-01

    Full Text Available In this study, the dehydrogenation component of Ga2O3 was introduced into ZSM-5 nanocrystals to prepare Ga2O3/ZSM-5 hollow fiber-based bifunctional catalysts. The physicochemical features of as-prepared catalysts were characterized by means of XRD, BET, SEM, STEM, NH3-TPD, etc., and their performances for the catalytic conversion of n-butane to produce light olefins and aromatics were investigated. The results indicated that a very small amount of gallium can cause a marked enhancement in the catalytic activity of ZSM-5 because of the synergistic effect of the dehydrogenation and aromatization properties of Ga2O3 and the cracking function of ZSM-5. Compared with Ga2O3/ZSM-5 nanoparticles, the unique hierarchical macro-meso-microporosity of the as-prepared hollow fibers can effectively enlarge the bifunctionality by enhancing the accessibility of active sites and the diffusion. Consequently, Ga2O3/ZSM-5 hollow fibers show excellent catalytic conversion of n-butane, with the highest yield of light olefins plus aromatics at 600 °C by 87.6%, which is 56.3%, 24.6%, and 13.3% higher than that of ZSM-5, ZSM-5 zeolite fibers, and Ga2O3/ZSM-5, respectively.

  17. Optical activity of catalytic elements of hetero-metallic nanostructures

    Science.gov (United States)

    Antosiewicz, Tomasz J.; Apell, S. Peter; Wadell, Carl; Langhammer, Christoph

    2015-05-01

    Interaction of light with metals in the form of surface plasmons is used in a wide range of applications in which the scattering decay channel is important. The absorption channel is usually thought of as unwanted and detrimental to the efficiency of the device. This is true in many applications, however, recent studies have shown that maximization of the decay channel of surface plasmons has potentially significant uses. One of these is the creation of electron-hole pairs or hot electrons which can be used for e.g. catalysis. Here, we study the optical properties of hetero-metallic nanostructures that enhance light interaction with the catalytic elements of the nanostructures. A hybridized LSPR that matches the spectral characteristic of the light source is excited. This LSPR through coupling between the plasmonic elements maximizes light absorption in the catalytic part of the nanostructure. Numerically calculated visible light absorption in the catalytic nanoparticles is enhanced 12-fold for large catalytic disks and by more 30 for small nanoparticles on the order of 5 nm. In experiments we measure a sizable increase in the absorption cross section when small palladium nanoparticles are coupled to a large silver resonator. These observations suggest that heterometallic nanostructures can enhance catalytic reaction rates.

  18. Human IgE is efficiently produced in glycosylated and biologically active form in lepidopteran cells.

    Science.gov (United States)

    Bantleon, Frank; Wolf, Sara; Seismann, Henning; Dam, Svend; Lorentzen, Andrea; Miehe, Michaela; Jabs, Frederic; Jakob, Thilo; Plum, Melanie; Spillner, Edzard

    2016-04-01

    TH2-biased immunity to parasites and allergens is often associated with increased levels of antigen-specific and high affinity IgE. The role in reacting against minute amounts of target structures and to provoke severe anaphylactic reactions renders IgE a mechanistically outstanding isotype. IgE represents the least abundant serum antibody isotype and exhibits a variety of peculiarities including structure, extensive glycosylation and effector functions. Despite large progress in antibody technologies, however, the recombinant access to isotypes beyond IgG such as IgE still is scarce. The capacity of expression systems has to meet the complex structural conformations and the extensive posttranslational modifications that are indispensable for biological activity. In order to provide alternatives to mammalian expression systems with often low yield and a more complex glycosylation pattern we established the recombinant production of the highly complex IgE isotype in insect cells. Recombinant IgE (rIgE) was efficiently assembled and secreted into the supernatant in yields of >30 mg/L. Purification from serum free medium using different downstream processing methods provided large amounts of rIgE. This exhibited a highly specific interaction with its antigen, therapeutic anti-IgE and its high affinity receptor, the FcεRI. Lectins and glyco-proteomic analyses proved the presence of prototypic insect type N-glycans on the epsilon heavy chain. Mediator release assays demonstrated a biological activity of the rIgE comparable to IgE derived from mammalian cells. In summary the expression in insect cells provides rIgE with variant glycosylation pattern, but retained characteristics and biological activity. Therefore our data contribute to the understanding of functional and structural aspects and potential use of the IgE isotype. PMID:26943931

  19. Efficient measurement of point-to-set correlations and overlap fluctuations in glass-forming liquids

    International Nuclear Information System (INIS)

    Cavity point-to-set correlations are real-space tools to detect the roughening of the free-energy landscape that accompanies the dynamical slowdown of glass-forming liquids. Measuring these correlations in model glass formers remains, however, a major computational challenge. Here, we develop a general parallel-tempering method that provides orders-of-magnitude improvement for sampling and equilibrating configurations within cavities. We apply this improved scheme to the canonical Kob-Andersen binary Lennard-Jones model for temperatures down to the mode-coupling theory crossover. Most significant improvements are noted for small cavities, which have thus far been the most difficult to study. This methodological advance also enables us to study a broader range of physical observables associated with thermodynamic fluctuations. We measure the probability distribution of overlap fluctuations in cavities, which displays a non-trivial temperature evolution. The corresponding overlap susceptibility is found to provide a robust quantitative estimate of the point-to-set length scale requiring no fitting. By resolving spatial fluctuations of the overlap in the cavity, we also obtain quantitative information about the geometry of overlap fluctuations. We can thus examine in detail how the penetration length as well as its fluctuations evolve with temperature and cavity size

  20. Efficient measurement of point-to-set correlations and overlap fluctuations in glass-forming liquids

    Energy Technology Data Exchange (ETDEWEB)

    Berthier, Ludovic [Laboratoire Charles Coulomb, UMR 5221 CNRS and Université de Montpellier, Montpellier (France); Charbonneau, Patrick [Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States); Department of Physics, Duke University, Durham, North Carolina 27708 (United States); Yaida, Sho, E-mail: sho.yaida@duke.edu [Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States)

    2016-01-14

    Cavity point-to-set correlations are real-space tools to detect the roughening of the free-energy landscape that accompanies the dynamical slowdown of glass-forming liquids. Measuring these correlations in model glass formers remains, however, a major computational challenge. Here, we develop a general parallel-tempering method that provides orders-of-magnitude improvement for sampling and equilibrating configurations within cavities. We apply this improved scheme to the canonical Kob-Andersen binary Lennard-Jones model for temperatures down to the mode-coupling theory crossover. Most significant improvements are noted for small cavities, which have thus far been the most difficult to study. This methodological advance also enables us to study a broader range of physical observables associated with thermodynamic fluctuations. We measure the probability distribution of overlap fluctuations in cavities, which displays a non-trivial temperature evolution. The corresponding overlap susceptibility is found to provide a robust quantitative estimate of the point-to-set length scale requiring no fitting. By resolving spatial fluctuations of the overlap in the cavity, we also obtain quantitative information about the geometry of overlap fluctuations. We can thus examine in detail how the penetration length as well as its fluctuations evolve with temperature and cavity size.

  1. Black Nitrogen or Plant-Derived Organic Nitrogen - which Form is More Efficiently Sequestered in Soils?

    Science.gov (United States)

    López-Martín, María; Velasco-Molina, Marta; Knicker, Heike

    2014-05-01

    Input of charcoal after forest fires can lead to considerable changes of the quality and quantity of organic matter in soils (SOM). This affects not only its organic C pool but also shifts its organic N composition from peptideous to N-heterocyclic structures (Knicker et al., 1996). In the present study we sought to understand how this alteration is affecting the N availability in fire affected soils. Therefore, we performed a medium-term pot experiment in which grass material (Lolium perenne) was grown on soil material (Cambisols) of a fire-affected and a fire-unaffected forest. The soils were topped with mixtures of ground fresh grass residues and KNO3 or charred grass material (pyrogenic organic matter; PyOM) with KNO3. Here, either the organic N or the inorganic N was isotopically enriched with 15N. Following the 15N concentration in the soil matrix and the growing plants as a function of incubation time (up to 16 months) by isotopic ratio mass spectrometry allowed us to indentify which N-source is most efficiently stabilized and how PyOM is affecting this process. Preliminary data indicated that only after the germination of the seeds, the concentration of the added inorganic 15N in the soil decreased considerably most likely due to its uptake by the growing plants but also due to N-losses by leaching and volatilization. Additional addition of plant residues or PyOM had no major effect on this behavior. Covering the soil with 15N-grass residues which simulates a litter layer led to a slow increase of the 15N concentration in the mineral soil during the first month. This is best explained by the ongoing incorporation of the litter into the soil matrix. After that a small decrease was observed, showing that the organic N was only slowly mobilized. Addition of 15N-PyOM showed a comparable behavior but with 15N concentration in the soil corresponding to twice of those of the pots amended with 15N-grass residues. After that the 15N concentrations decrease quickly

  2. Catalytic fast pyrolysis of lignocellulosic biomass

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Changjun; Wang, Huamin; Karim, Ayman M.; Sun, Junming; Wang, Yong

    2014-11-21

    Increasing energy demand, especially in the transportation sector, and soaring CO2 emissions necessitate the exploitation of renewable sources of energy. Despite the large variety of new energy Q3 carriers, liquid hydrocarbon still appears to be the most attractive and feasible form of transportation fuel taking into account the energy density, stability and existing infrastructure. Biomass is an abundant, renewable source of energy; however, utilizing it in a cost-effective way is still a substantial challenge. Lignocellulose is composed of three major biopolymers, namely cellulose, hemicellulose and lignin. Fast pyrolysis of biomass is recognized as an efficient and feasible process to selectively convert lignocellulose into a liquid fuel—bio-oil. However bio-oil from fast pyrolysis contains a large amount of oxygen, distributed in hundreds of oxygenates. These oxygenates are the cause of many negative properties, such as low heating values, high corrosiveness, high viscosity, and instability; they also greatly Q4 limit the application of bio-oil particularly as transportation fuel. Hydrocarbons derived from biomass are most attractive because of their high energy density and compatibility with the existing infrastructure. Thus, converting lignocellulose into transportation fuels via catalytic fast pyrolysis has attracted much attention. Many studies related to catalytic fast pyrolysis of biomass have been published. The main challenge of this process is the development of active and stable catalysts that can deal with a large variety of decomposition intermediates from lignocellulose. This review starts with the current understanding of the chemistry in fast pyrolysis of lignocellulose and focuses on the development of catalysts in catalytic fast pyrolysis. Recent progress in the experimental studies on catalytic fast pyrolysis of biomass is also summarized with the emphasis on bio-oil yields and quality.

  3. Theoretical Foundations of Efficiently Organizing Production Processes: Using the Example of Combining Organizational Forms of Component Manufacture and Internal Transport

    Directory of Open Access Journals (Sweden)

    Anne-Katrin Schroeder

    2014-01-01

    Full Text Available This paper examines the problem of efficient production processes organization down to subprocesses levels. Subtasks of production within subprocesses necessitate a specific set of requirements for production organization. Through particular features and their respective characteristics, these requirements are further systemized and described as process types. The main manufacturing process “component manufacture” and its connected production support service “internal transport” have been chosen as examples to show relevant organizational principles and forms. From this baseline and together with a decision algorithm, selected organizational options and a combination thereof shall lead to theoretically optimized solutions which meet all predefined requirements. A multilevel organizational alignment model lays out interdependencies of combined process type-oriented organizational forms. Methods of comparative organizational profile analysis in support of reengineering approaches are systemized and further developed towards resulting organizational adaptations.

  4. Optimization of Process Parameters for High Efficiency Laser Forming of Advanced High Strength Steels within Metallurgical Constraints

    Science.gov (United States)

    Sheikholeslami, Ghazal; Griffiths, Jonathan; Dearden, Geoff; Edwardson, Stuart P.

    Laser forming (LF) has been shown to be a viable alternative to form automotive grade advanced high strength steels (AHSS). Due to their high strength, heat sensitivity and low conventional formability show early fractures, larger springback, batch-to-batch inconsistency and high tool wear. In this paper, optimisation of the LF process parameters has been conducted to further understand the impact of a surface heat treatment on DP1000. A FE numerical simulation has been developed to analyse the dynamic thermo-mechanical effects. This has been verified against empirical data. The goal of the optimisation has been to develop a usable process window for the LF of AHSS within strict metallurgical constraints. Results indicate it is possible to LF this material, however a complex relationship has been found between the generation and maintenance of hardness values in the heated zone. A laser surface hardening effect has been observed that could be beneficial to the efficiency of the process.

  5. Molecular Recognition of the Catalytic Zinc(II Ion in MMP-13: Structure-Based Evolution of an Allosteric Inhibitor to Dual Binding Mode Inhibitors with Improved Lipophilic Ligand Efficiencies

    Directory of Open Access Journals (Sweden)

    Thomas Fischer

    2016-03-01

    Full Text Available Matrix metalloproteinases (MMPs are a class of zinc dependent endopeptidases which play a crucial role in a multitude of severe diseases such as cancer and osteoarthritis. We employed MMP-13 as the target enzyme for the structure-based design and synthesis of inhibitors able to recognize the catalytic zinc ion in addition to an allosteric binding site in order to increase the affinity of the ligand. Guided by molecular modeling, we optimized an initial allosteric inhibitor by addition of linker fragments and weak zinc binders for recognition of the catalytic center. Furthermore we improved the lipophilic ligand efficiency (LLE of the initial inhibitor by adding appropriate zinc binding fragments to lower the clogP values of the inhibitors, while maintaining their potency. All synthesized inhibitors showed elevated affinity compared to the initial hit, also most of the novel inhibitors displayed better LLE. Derivatives with carboxylic acids as the zinc binding fragments turned out to be the most potent inhibitors (compound 3 (ZHAWOC5077: IC50 = 134 nM whereas acyl sulfonamides showed the best lipophilic ligand efficiencies (compound 18 (ZHAWOC5135: LLE = 2.91.

  6. Molecular Recognition of the Catalytic Zinc(II) Ion in MMP-13: Structure-Based Evolution of an Allosteric Inhibitor to Dual Binding Mode Inhibitors with Improved Lipophilic Ligand Efficiencies.

    Science.gov (United States)

    Fischer, Thomas; Riedl, Rainer

    2016-01-01

    Matrix metalloproteinases (MMPs) are a class of zinc dependent endopeptidases which play a crucial role in a multitude of severe diseases such as cancer and osteoarthritis. We employed MMP-13 as the target enzyme for the structure-based design and synthesis of inhibitors able to recognize the catalytic zinc ion in addition to an allosteric binding site in order to increase the affinity of the ligand. Guided by molecular modeling, we optimized an initial allosteric inhibitor by addition of linker fragments and weak zinc binders for recognition of the catalytic center. Furthermore we improved the lipophilic ligand efficiency (LLE) of the initial inhibitor by adding appropriate zinc binding fragments to lower the clogP values of the inhibitors, while maintaining their potency. All synthesized inhibitors showed elevated affinity compared to the initial hit, also most of the novel inhibitors displayed better LLE. Derivatives with carboxylic acids as the zinc binding fragments turned out to be the most potent inhibitors (compound 3 (ZHAWOC5077): IC50 = 134 nM) whereas acyl sulfonamides showed the best lipophilic ligand efficiencies (compound 18 (ZHAWOC5135): LLE = 2.91). PMID:26938528

  7. BcsA and BcsB form the catalytically active core of bacterial cellulose synthase sufficient for in vitro cellulose synthesis

    OpenAIRE

    Omadjela, Okako; Narahari, Adishesh; Strumillo, Joanna; Mélida, Hugo; Mazur, Olga; Bulone, Vincent; Zimmer, Jochen

    2013-01-01

    Cellulose is the most abundant biopolymer on Earth, primarily formed by vascular plants, but also by some bacteria. Bacterial extracellular polysaccharides, such as cellulose and alginate, are an important component of biofilms, which are multicellular, usually sessile, aggregates of bacteria. Biofilms exhibit a greater resistance to antimicrobial treatments compared with isolated bacteria and thus are a particular concern to human health. Cellulose synthases synthesize cellulose by polymeriz...

  8. Plasmonic enhancement of the optical absorption and catalytic efficiency of BiVO₄ photoanodes decorated with Ag@SiO₂ core-shell nanoparticles.

    Science.gov (United States)

    Abdi, Fatwa F; Dabirian, Ali; Dam, Bernard; van de Krol, Roel

    2014-08-01

    Recent progress in the development of bismuth vanadate (BiVO4) photoanodes has firmly established it as a promising material for solar water splitting applications. Performance limitations due to intrinsically poor catalytic activity and slow electron transport have been successfully addressed through the application of water oxidation co-catalysts and novel doping strategies. The next bottleneck to tackle is the modest optical absorption in BiVO4, particularly close to its absorption edge of 2.4 eV. Here, we explore the modification of the BiVO4 surface with Ag@SiO2 core-shell plasmonic nanoparticles. A photocurrent enhancement by a factor of ~2.5 is found under 1 sun illumination (AM1.5). We show that this enhancement consists of two contributions: optical absorption and catalysis. The optical absorption enhancement is induced by the excitation of localized surface plasmon resonances in the Ag nanoparticles, and agrees well with our full-field electromagnetic simulations. Far-field effects (scattering) are found to be dominant, with a smaller contribution from near-field plasmonic enhancement. In addition, a significant catalytic enhancement is observed, which is tentatively attributed to the electrocatalytic activity of the Ag@SiO2 nanoparticles. PMID:24942363

  9. Connection between the packing efficiency of binary hard spheres and the glass-forming ability of bulk metallic glasses.

    Science.gov (United States)

    Zhang, Kai; Smith, W Wendell; Wang, Minglei; Liu, Yanhui; Schroers, Jan; Shattuck, Mark D; O'Hern, Corey S

    2014-09-01

    We perform molecular dynamics simulations to compress binary hard spheres into jammed packings as a function of the compression rate R, size ratio α, and number fraction x(S) of small particles to determine the connection between the glass-forming ability (GFA) and packing efficiency in bulk metallic glasses (BMGs). We define the GFA by measuring the critical compression rate R(c), below which jammed hard-sphere packings begin to form "random crystal" structures with defects. We find that for systems with α≳0.8 that do not demix, R(c) decreases strongly with Δϕ(J), as R(c)∼exp(-1/Δϕ(J)(2)), where Δϕ(J) is the difference between the average packing fraction of the amorphous packings and random crystal structures at R(c). Systems with α≲0.8 partially demix, which promotes crystallization, but we still find a strong correlation between R(c) and Δϕ(J). We show that known metal-metal BMGs occur in the regions of the α and x(S) parameter space with the lowest values of R(c) for binary hard spheres. Our results emphasize that maximizing GFA in binary systems involves two competing effects: minimizing α to increase packing efficiency, while maximizing α to prevent demixing.

  10. Association efficiency of three ionic forms of oxytetracycline to cationic and anionic oil-in-water nanoemulsions analyzed by diafiltration.

    Science.gov (United States)

    Orellana, Sandra L; Torres-Gallegos, Cesar; Araya-Hermosilla, Rodrigo; Oyarzun-Ampuero, Felipe; Moreno-Villoslada, Ignacio

    2015-03-01

    The association efficiency of oxytetracycline (OTC) to pharmaceutical available, ionic oil-in-water nanoemulsions is studied. Theoretical mathematical developments allowed us to differentiate by diafiltration (DF) between thermodynamically and kinetically controlled binding of the drug to the nanoemulsions, and relate these important magnitudes to the association efficiency. The nanoemulsions have been prepared by the solvent displacement technique in the presence of cationic and anionic surfactants. The resulting nanoemulsions were stable at 4°C and 25°C for 60 days, have a size of ∼ 200 nm, showing polydispersity indexes ranging between 0.11 and 0.23, and present zeta potentials ranging between -90 and +60 mV, depending on the charge of the surfactants used. The zeta potential of the nanoemulsions influenced the interaction with OTC, having three ionic forms at different pH, namely, cationic, zwitterionic, and anionic. DF proved to be a powerful tool for the quantification of the drug association efficiency, achieving values up to 84%. Furthermore, this technique allowed obtaining different values of the drug fractions reversibly bound (11%-57%) and irreversibly bound (10%-40%) to the nanoemulsions depending on the surfactants used and pH. These findings may be useful for the development of new drug delivery systems, and as routine assays in academia and pharmaceutical industries. PMID:25557590

  11. Stoichiometric and Catalytic Synthesis of Alkynylphosphines

    Directory of Open Access Journals (Sweden)

    Annie-Claude Gaumont

    2012-12-01

    Full Text Available Alkynylphosphines or their borane complexes are available either through C–P bond forming reactions or through modification of the phosphorus or the alkynyl function of various alkynyl phosphorus derivatives. The latter strategy, and in particular the one involving phosphoryl reduction by alanes or silanes, is the method of choice for preparing primary and secondary alkynylphosphines, while the former strategy is usually employed for the synthesis of tertiary alkynylphosphines or their borane complexes. The classical C–P bond forming methods rely on the reaction between halophosphines or their borane complexes with terminal acetylenes in the presence of a stoichiometric amount of organometallic bases, which precludes the access to alkynylphosphines bearing sensitive functional groups. In less than a decade, efficient catalytic procedures, mostly involving copper complexes and either an electrophilic or a nucleophilic phosphorus reagent, have emerged. By proceeding under mild conditions, these new methods have allowed a significant broadening of the substituent scope and structure complexity.

  12. Sent packing: protein engineering generates a new crystal form of Pseudomonas aeruginosa DsbA1 with increased catalytic surface accessibility

    Energy Technology Data Exchange (ETDEWEB)

    McMahon, Roisin M., E-mail: r.mcmahon1@uq.edu.au; Coinçon, Mathieu; Tay, Stephanie; Heras, Begoña [University of Queensland, 306 Carmody Road, Brisbane, Queensland 4072 (Australia); Morton, Craig J. [Biota Holdings Limited, Unit 10, 585 Blackburn Road, Notting Hill, Victoria 3168 (Australia); Scanlon, Martin J. [Monash University, 381 Royal Parade, Parkville, Victoria 3052 (Australia); Martin, Jennifer L. [University of Queensland, 306 Carmody Road, Brisbane, Queensland 4072 (Australia)

    2015-11-26

    The crystal structure of a P. aeruginosa DsbA1 variant is more suitable for fragment-based lead discovery efforts to identify inhibitors of this antimicrobial drug target. In the reported structures the active site of the protein can simultaneously bind multiple ligands introduced in the crystallization solution or via soaking. Pseudomonas aeruginosa is an opportunistic human pathogen for which new antimicrobial drug options are urgently sought. P. aeruginosa disulfide-bond protein A1 (PaDsbA1) plays a pivotal role in catalyzing the oxidative folding of multiple virulence proteins and as such holds great promise as a drug target. As part of a fragment-based lead discovery approach to PaDsbA1 inhibitor development, the identification of a crystal form of PaDsbA1 that was more suitable for fragment-soaking experiments was sought. A previously identified crystallization condition for this protein was unsuitable, as in this crystal form of PaDsbA1 the active-site surface loops are engaged in the crystal packing, occluding access to the target site. A single residue involved in crystal-packing interactions was substituted with an amino acid commonly found at this position in closely related enzymes, and this variant was successfully used to generate a new crystal form of PaDsbA1 in which the active-site surface is more accessible for soaking experiments. The PaDsbA1 variant displays identical redox character and in vitro activity to wild-type PaDsbA1 and is structurally highly similar. Two crystal structures of the PaDsbA1 variant were determined in complex with small molecules bound to the protein active site. These small molecules (MES, glycerol and ethylene glycol) were derived from the crystallization or cryoprotectant solutions and provide a proof of principle that the reported crystal form will be amenable to co-crystallization and soaking with small molecules designed to target the protein active-site surface.

  13. Efficiency

    NARCIS (Netherlands)

    I.P. van Staveren (Irene)

    2009-01-01

    textabstractThe dominant economic theory, neoclassical economics, employs a single economic evaluative criterion: efficiency. Moreover, it assigns this criterion a very specific meaning. Other – heterodox – schools of thought in economics tend to use more open concepts of efficiency, related to comm

  14. Silver nanocluster catalytic microreactors for water purification

    Science.gov (United States)

    Da Silva, B.; Habibi, M.; Ognier, S.; Schelcher, G.; Mostafavi-Amjad, J.; Khalesifard, H. R. M.; Tatoulian, M.; Bonn, D.

    2016-07-01

    A new method for the elaboration of a novel type of catalytic microsystem with a high specific area catalyst is developed. A silver nanocluster catalytic microreactor was elaborated by doping a soda-lime glass with a silver salt. By applying a high power laser beam to the glass, silver nanoclusters are obtained at one of the surfaces which were characterized by BET measurements and AFM. A microfluidic chip was obtained by sealing the silver coated glass with a NOA 81 microchannel. The catalytic activity of the silver nanoclusters was then tested for the efficiency of water purification by using catalytic ozonation to oxidize an organic pollutant. The silver nanoclusters were found to be very stable in the microreactor and efficiently oxidized the pollutant, in spite of the very short residence times in the microchannel. This opens the way to study catalytic reactions in microchannels without the need of introducing the catalyst as a powder or manufacturing complex packed bed microreactors.

  15. A General Method for Constructing Two-Dimensional Layered Mesoporous Mono- and Binary-Transition-Metal Nitride/Graphene as an Ultra-Efficient Support to Enhance Its Catalytic Activity and Durability for Electrocatalytic Application.

    Science.gov (United States)

    Liu, Baocang; Huo, Lili; Si, Rui; Liu, Jian; Zhang, Jun

    2016-07-27

    We constructed a series of two-dimensional (2D) layered mesoporous mono- and binary-transition-metal nitride/graphene nanocomposites (TMN/G, TM = Ti, Cr, W, Mo, TiCr, TiW, and TiMo) via an efficient and versatile nanocasting strategy for the first time. The 2D layered mesoporous TMN/G is constituted of small TMN nanoparticles composited with graphene nanosheets and has a large surface area with high porosity. Through decoration with well-dispersed Pt nanoparticles, 2D layered mesoporous Pt/TMN/G catalysts can be obtained that display excellent catalytic activity and stability for methanol electro-oxidation reactions (MOR) and oxygen reduction reactions (ORR) in both acidic and alkaline media. The 2D layered mesoporous binary-Pt/TMN/G catalysts possess catalytic activity superior to that of mono-Pt/TMN/G, graphene free Pt/TMN, Pt/G, and Pt/C catalysts. Encouragingly, the 2D layered mesoporous Pt/Ti0.5Cr0.5N/G catalyst exhibits the best electrocatalytic performance for both MOR and ORR. The outstanding electrocatalytic performance of the Pt/Ti0.5Cr0.5N/G catalyst is rooted in its large surface area, high porosity, strong interaction among Pt, Ti0.5Cr0.5N, and graphene, an excellent electron transfer property facilitated by N-doped graphene, and the small size of Pt and Ti0.5Cr0.5N nanocrystals. The outstanding catalytic performance provides the 2D layered mesoporous Pt/Ti0.5Cr0.5N/G catalyst with a wide range of application prospects in direct methanol fuel cells in both acidic and alkaline media. The synthetic method may be available for constructing other 2D layered mesoporous metal nitrides, carbides, and phosphides. PMID:27356463

  16. Different crystal-forms of one-dimensional MnO2 nanomaterials for the catalytic oxidation and adsorption of elemental mercury.

    Science.gov (United States)

    Xu, Haomiao; Qu, Zan; Zhao, Songjian; Mei, Jian; Quan, Fuquan; Yan, Naiqiang

    2015-12-15

    MnO2 has been found to be a promising material to capture elemental mercury (Hg(0)) from waste gases. To investigate the structure effect on Hg(0) uptake, three types of one-dimensional (1D) MnO2 nano-particles, α-, β- and γ-MnO2, were successfully prepared and tested. The structures of α-, β- and γ-MnO2 were characterized by XRD, BET, TEM and SEM. The results indicate that α-, β- and γ-MnO2 were present in the morphologies of belt-, rod- and spindle-like 1D materials, respectively. These findings demonstrated noticeably different activities in capturing Hg(0), depending on the surface area and crystalline structure. The performance enhancement is in the order of: β-MnO2removal using MnO2 was discussed with the help of results from H2-TPR, XPS and Hg(0) removal experiments in the absence of O2. It was determined that the oxidizability of three forms of MnO2 increased as follows: β-MnO2mercury and manganese oxide sites are demonstrated to increase in the following order: β-MnO2<γ-MnO2<α-MnO2 based on the desorption tests. PMID:26093358

  17. Removal performance and mechanism of ibuprofen from water by catalytic ozonation using sludge-corncob activated carbon as catalyst.

    Science.gov (United States)

    Wang, Hongjuan; Zhang, Liqiu; Qi, Fei; Wang, Xue; Li, Lu; Feng, Li

    2014-09-01

    To discover the catalytic activity of sludge-corncob activated carbon in catalytic ozonation of Ibuprofen, the performance of sludge-corncob activated carbon and three selected commercial activated carbons as catalysts in catalytic ozonation was investigated. The observation indicates the degradation rate of Ibuprofen increases significantly in the presence of sludge-corncob activated carbon and the catalytic activity of sludge-corncob activated carbon is much higher than that of the other three commercial activated carbons. Ibuprofen's removal rate follows pseudo-first order kinetics model well. It is also found that the adsorption removal of Ibuprofen by sludge-corncob activated carbon is less than 30% after 40 min. And the removal efficiency of Ibuprofen in the hybrid ozone/sludge-corncob activated carbon system is higher than the sum of sludge-corncob activated carbon adsorption and ozonation alone, which is a supportive evidence for catalytic reaction. In addition, the results of radical scavenger experiments demonstrate that catalytic ozonation of Ibuprofen by sludge-corncob activated carbon follows a hydroxyl radical reaction pathway. During ozonation of Ibuprofen in the presence of activated carbon, ozone could be catalytically decomposed to form hydrogen peroxide, which can promote the formation of hydroxyl radical. The maximum amount of hydrogen peroxide occurs in the presence of sludge-corncob activated carbon, which can explain why sludge-corncob activated carbon has the best catalytic activity among four different activated carbons.

  18. Efficiently Delivering Data Packets Using Distributed Protocol for Runtime Groups Formed In Peer-to-Peer Network

    Directory of Open Access Journals (Sweden)

    Yasa Ramya

    2011-09-01

    Full Text Available Peer-to-Peer streaming has been widely used over the internet, where a streaming system usually has multiple channels and peers may form multiple groups for content distribution. In this paper, we propose a distributed overlay framework called SMesh (subset-mesh for dynamic groups where users may frequently hop from one group to another. SMesh first builds a relatively stable mesh consisting of all hosts for control messaging. The mesh supports dynamic host joining and leaving, and construction of delivery trees. Using the Delaunay Triangulation protocol as an example, we show how to construct an efficient mesh with low maintenance cost. We also study about various tree constructions based on the mesh, including embedded, bypass, and intermediate trees.

  19. [Estimation of clinical-pathogenetic efficiency of reamberin and cycloferon application in patients with the severe form of acute tonsillitis].

    Science.gov (United States)

    Frolov, V M; Tereshkin, V A; Sotskaia, Ia A; Peresadin, N A; Kruglova, O V

    2013-03-01

    Efficiency of reamberin and cycloferon application combination at the patients with the heavy form of acute tonsillitis was investigated. It is set that cycloferon and reamberin application in the complex of treatment of the patients with this pathology is instrumental in normalization of the general state and feel of patients, liquidation of both commontoxic syndrome and local inflammatory displays in pharynx, and also normalization of the studied biochemical and immunological indexes. Application of cycloferon and reamberin provides the decline of "average molecules" and malon dialdehyde level to norm, that testifies about liquidation endogenous "metabolic" intoxication syndrome, and also instrumental in normalization of phagocytes activity of monocytes indexes, that describe normalize operating of the indicated preparation on the macrophage phagocytes system. PMID:24605622

  20. Enhanced quantum efficiency from a mosaic of two dimensional MoS2 formed onto aminosilane functionalised substrates

    Science.gov (United States)

    Wang, Yichao; Della Gaspera, Enrico; Carey, Benjamin J.; Atkin, Paul; Berean, Kyle J.; Clark, Rhiannon M.; Cole, Ivan S.; Xu, Zai-Quan; Zhang, Yupeng; Bao, Qiaoliang; Ou, Jian Zhen; Daeneke, Torben; Kalantar-Zadeh, Kourosh

    2016-06-01

    Developing scalable methods of growing two dimensional molybdenum disulphide (2D MoS2) with strong optical properties, on any desired substrates, is a necessary step towards industrial uptake of this material for optical applications. In this study, Si/SiO2 substrates were functionalised using self-assembled monolayers of three different aminosilanes with various numbers of amine groups and molecular lengths as underlayers for enhancing the adherence of the molybdenum precursor. The tetrahedral [MoS4]2- anion groups from the molybdenum precursor were bonded on these silanised Si/SiO2 substrates afterwards. The substrates were then treated with a combined thermolysis and sulphurisation step. The results showed that silanisation of the substrates using the longest chains and the largest number of amine groups provided a good foundation to grow quasi 2D MoS2 made from adjacent flakes in a mosaic formation. Microscopy and spectroscopy investigations revealed that these quasi 2D MoS2 formed using this long chain aminosilane resulted in flakes with lateral dimensions in micron and submicron ranges composed of adjoining MoS2 pieces of 20 to 60 nm in lateral dimensions, dominantly made of 3 to 5 MoS2 fundamental layers. The obtained quasi 2D MoS2 shows a high internal quantum efficiency of 2.6% associated with the quantum confinement effect and high stoichiometry of the adjoining nanoflakes that form the structure of the sheets. The synthesis technique in this study is reliable and facile and offers a procedure to form large, scalable and patternable quasi 2D MoS2 sheets on various substrates with enhanced optical properties for practical applications.Developing scalable methods of growing two dimensional molybdenum disulphide (2D MoS2) with strong optical properties, on any desired substrates, is a necessary step towards industrial uptake of this material for optical applications. In this study, Si/SiO2 substrates were functionalised using self-assembled monolayers of

  1. Plasma coating formed TIO2 catalysts usage in cleaning the air from nitrogen oxides and carbon monoxide

    OpenAIRE

    Vitalij Kolodynskij; Pranas Baltrėnas

    2015-01-01

    The present catalytic air purification device–air cleaning device is capable to reduce nitrogen oxide sand carbon monoxide concentrations in polluted air stream and to achieve high cleaning efficiency. The principle of operation of catalytic air cleaning device is based on plasma coating formed catalysts usage. At high temperatures and oxygen concentrations in the experimental device channel, catalysts become active and reactions of conversion of pollutants start. In this research, the effici...

  2. Enhanced quantum efficiency from a mosaic of two dimensional MoS2 formed onto aminosilane functionalised substrates.

    Science.gov (United States)

    Wang, Yichao; Della Gaspera, Enrico; Carey, Benjamin J; Atkin, Paul; Berean, Kyle J; Clark, Rhiannon M; Cole, Ivan S; Xu, Zai-Quan; Zhang, Yupeng; Bao, Qiaoliang; Ou, Jian Zhen; Daeneke, Torben; Kalantar-Zadeh, Kourosh

    2016-06-16

    Developing scalable methods of growing two dimensional molybdenum disulphide (2D MoS2) with strong optical properties, on any desired substrates, is a necessary step towards industrial uptake of this material for optical applications. In this study, Si/SiO2 substrates were functionalised using self-assembled monolayers of three different aminosilanes with various numbers of amine groups and molecular lengths as underlayers for enhancing the adherence of the molybdenum precursor. The tetrahedral [MoS4](2-) anion groups from the molybdenum precursor were bonded on these silanised Si/SiO2 substrates afterwards. The substrates were then treated with a combined thermolysis and sulphurisation step. The results showed that silanisation of the substrates using the longest chains and the largest number of amine groups provided a good foundation to grow quasi 2D MoS2 made from adjacent flakes in a mosaic formation. Microscopy and spectroscopy investigations revealed that these quasi 2D MoS2 formed using this long chain aminosilane resulted in flakes with lateral dimensions in micron and submicron ranges composed of adjoining MoS2 pieces of 20 to 60 nm in lateral dimensions, dominantly made of 3 to 5 MoS2 fundamental layers. The obtained quasi 2D MoS2 shows a high internal quantum efficiency of 2.6% associated with the quantum confinement effect and high stoichiometry of the adjoining nanoflakes that form the structure of the sheets. The synthesis technique in this study is reliable and facile and offers a procedure to form large, scalable and patternable quasi 2D MoS2 sheets on various substrates with enhanced optical properties for practical applications.

  3. Enhanced quantum efficiency from a mosaic of two dimensional MoS2 formed onto aminosilane functionalised substrates.

    Science.gov (United States)

    Wang, Yichao; Della Gaspera, Enrico; Carey, Benjamin J; Atkin, Paul; Berean, Kyle J; Clark, Rhiannon M; Cole, Ivan S; Xu, Zai-Quan; Zhang, Yupeng; Bao, Qiaoliang; Ou, Jian Zhen; Daeneke, Torben; Kalantar-Zadeh, Kourosh

    2016-06-16

    Developing scalable methods of growing two dimensional molybdenum disulphide (2D MoS2) with strong optical properties, on any desired substrates, is a necessary step towards industrial uptake of this material for optical applications. In this study, Si/SiO2 substrates were functionalised using self-assembled monolayers of three different aminosilanes with various numbers of amine groups and molecular lengths as underlayers for enhancing the adherence of the molybdenum precursor. The tetrahedral [MoS4](2-) anion groups from the molybdenum precursor were bonded on these silanised Si/SiO2 substrates afterwards. The substrates were then treated with a combined thermolysis and sulphurisation step. The results showed that silanisation of the substrates using the longest chains and the largest number of amine groups provided a good foundation to grow quasi 2D MoS2 made from adjacent flakes in a mosaic formation. Microscopy and spectroscopy investigations revealed that these quasi 2D MoS2 formed using this long chain aminosilane resulted in flakes with lateral dimensions in micron and submicron ranges composed of adjoining MoS2 pieces of 20 to 60 nm in lateral dimensions, dominantly made of 3 to 5 MoS2 fundamental layers. The obtained quasi 2D MoS2 shows a high internal quantum efficiency of 2.6% associated with the quantum confinement effect and high stoichiometry of the adjoining nanoflakes that form the structure of the sheets. The synthesis technique in this study is reliable and facile and offers a procedure to form large, scalable and patternable quasi 2D MoS2 sheets on various substrates with enhanced optical properties for practical applications. PMID:27263805

  4. A novel approach for enhancing the catalytic efficiency of a protease at low temperature: reduction in substrate inhibition by chemical modification.

    Science.gov (United States)

    Siddiqui, Khawar Sohail; Parkin, Don M; Curmi, Paul M G; De Francisci, Davide; Poljak, Anne; Barrow, Kevin; Noble, Malcolm H; Trewhella, Jill; Cavicchioli, Ricardo

    2009-07-01

    The alkaline protease, savinase was chemically modified to enhance the productivity of the enzyme at low temperatures on a complex polymeric protein (azocasein) substrate. At 5 and 15 degrees C, savinase modified with ficol or dextran hydrolyzed fivefold more azocasein than the unmodified savinase. Kinetic studies showed that the catalytic improvements are associated with changes in uncompetitive substrate inhibition with K(i) values of modified savinases sixfold higher than the unmodified savinase. Modeling of small-angle scattering data indicates that two substrate molecules bind on opposing sides of the enzyme. The combined kinetic and structural data indicate that the polysaccharide modifier sterically blocks the allosteric site and reduces substrate inhibition. In contrast to the properties of cold-active enzymes that generally manifest as low activation enthalpy and high flexibility, this study shows that increased activity and productivity at low temperature can be achieved by reducing uncompetitive substrate inhibition, and that this can be achieved using chemical modification with an enzyme in a commercial enzyme-formulation. PMID:19288442

  5. An efficient route for catalytic activity promotion via hybrid electro-depositional modification on commercial nickel foam for hydrogen evolution reaction in alkaline water electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Guanshui; He, Yongwei; Wang, Mei; Zhu, Fuchun; Tang, Bin [Research Institute of Surface Engineering, Taiyuan University of Technology, Yingze West Road 79, Taiyuan 030024 (China); Wang, Xiaoguang, E-mail: wangxiaog1982@163.com [Research Institute of Surface Engineering, Taiyuan University of Technology, Yingze West Road 79, Taiyuan 030024 (China); International Iberian Nanotechnology Laboratory (INL), 4715-330 Braga (Portugal)

    2014-09-15

    Highlights: • Mono-Cu surface modification depress the HER activity of Ni-foam. • Hybrid Ni-foam/Cu0.01/Co0.05 exhibits superior HER performance. • Layer-by-layer structure may contribute to a synergistic promoting effect. - Abstract: In this paper, the single- and hybrid-layered Cu, Ni and Co thin films were electrochemically deposited onto the three-dimensional nickel foam as composite cathode catalyst for hydrogen evolution reaction in alkaline water electrolysis. The morphology, structure and chemical composition of the electrodeposited composite catalysts were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Electrochemical measurement depicted that, for the case of the monometallic layered samples, the general activity for hydrogen evolution reaction followed the sequence: Ni-foam/Ni > Ni-foam/Co > bare Ni-foam > Ni-foam/Cu. It is noteworthy that, the hybrid-layered Ni-foam/Cu0.01/Co0.05 exhibited the highest catalytic activity towards hydrogen evolution reaction with the current density as high as 2.82 times that of the bare Ni-foam. Moreover, both excellent electrochemical and physical stabilities can also be acquired on the Ni-foam/Cu0.01/Co0.05, making this hybrid-layered composite structure as a promising HER electro-catalyst.

  6. Preparation and Catalytic Oxidation Activity on 2-mercaptoethanol of a Novel Catalytic Cellulose Fibres

    Institute of Scientific and Technical Information of China (English)

    YAO Yu-yuan; LI Ying-jie; CHEN Wen-xing; Lü Wang-yang; Lü Su-fang; XU Min-hong; LIU Fan

    2007-01-01

    Cobalt tetra(N-carbonylacylic) aminophthalocyanine was supported on cellulose fibres by graft reaction to obtain a novel polymer catalyst, catalytic cellulose fibres (CCF),and the optimal supporting conditions were pH = 6, 80℃,t = 120 min. The catalytic oxidation activity of CCF towards oxidation of 2-mereaptoethanol (MEA) in aqueous solution was investigated. The experimental results demonstrated that CCF had good catalytic oxidation activity on MEA at room temperature, causing no secondary pollution and remaining efficient for the repetitive tests with no obvious decrease of catalytic activity.

  7. Mechanism of Ribonuclease III Catalytic Regulation by Serine Phosphorylation

    Science.gov (United States)

    Gone, Swapna; Alfonso-Prieto, Mercedes; Paudyal, Samridhdi; Nicholson, Allen W.

    2016-05-01

    Ribonuclease III (RNase III) is a conserved, gene-regulatory bacterial endonuclease that cleaves double-helical structures in diverse coding and noncoding RNAs. RNase III is subject to multiple levels of control, reflective of its global regulatory functions. Escherichia coli (Ec) RNase III catalytic activity is known to increase during bacteriophage T7 infection, reflecting the expression of the phage-encoded protein kinase, T7PK. However, the mechanism of catalytic enhancement is unknown. This study shows that Ec-RNase III is phosphorylated on serine in vitro by purified T7PK, and identifies the targets as Ser33 and Ser34 in the N-terminal catalytic domain. Kinetic experiments reveal a 5-fold increase in kcat and a 1.4-fold decrease in Km following phosphorylation, providing a 7.4–fold increase in catalytic efficiency. Phosphorylation does not change the rate of substrate cleavage under single-turnover conditions, indicating that phosphorylation enhances product release, which also is the rate-limiting step in the steady-state. Molecular dynamics simulations provide a mechanism for facilitated product release, in which the Ser33 phosphomonoester forms a salt bridge with the Arg95 guanidinium group, thereby weakening RNase III engagement of product. The simulations also show why glutamic acid substitution at either serine does not confer enhancement, thus underscoring the specific requirement for a phosphomonoester.

  8. Catalytic quantum error correction

    CERN Document Server

    Brun, T; Hsieh, M H; Brun, Todd; Devetak, Igor; Hsieh, Min-Hsiu

    2006-01-01

    We develop the theory of entanglement-assisted quantum error correcting (EAQEC) codes, a generalization of the stabilizer formalism to the setting in which the sender and receiver have access to pre-shared entanglement. Conventional stabilizer codes are equivalent to dual-containing symplectic codes. In contrast, EAQEC codes do not require the dual-containing condition, which greatly simplifies their construction. We show how any quaternary classical code can be made into a EAQEC code. In particular, efficient modern codes, like LDPC codes, which attain the Shannon capacity, can be made into EAQEC codes attaining the hashing bound. In a quantum computation setting, EAQEC codes give rise to catalytic quantum codes which maintain a region of inherited noiseless qubits. We also give an alternative construction of EAQEC codes by making classical entanglement assisted codes coherent.

  9. Catalytic mechanism of Zn2+-dependent polyol dehydrogenases: kinetic comparison of sheep liver sorbitol dehydrogenase with wild-type and Glu154→Cys forms of yeast xylitol dehydrogenase

    Science.gov (United States)

    Klimacek, Mario; Hellmer, Heidemarie; Nidetzky, Bernd

    2007-01-01

    Co-ordination of catalytic Zn2+ in sorbitol/xylitol dehydrogenases of the medium-chain dehydrogenase/reductase superfamily involves direct or water-mediated interactions from a glutamic acid residue, which substitutes a homologous cysteine ligand in alcohol dehydrogenases of the yeast and liver type. Glu154 of xylitol dehydrogenase from the yeast Galactocandida mastotermitis (termed GmXDH) was mutated to a cysteine residue (E154C) to revert this replacement. In spite of their variable Zn2+ content (0.10–0.40 atom/subunit), purified preparations of E154C exhibited a constant catalytic Zn2+ centre activity (kcat) of 1.19±0.03 s−1 and did not require exogenous Zn2+ for activity or stability. E154C retained 0.019±0.003% and 0.74±0.03% of wild-type catalytic efficiency (kcat/Ksorbitol=7800±700 M−1· s−1) and kcat (=161±4 s−1) for NAD+-dependent oxidation of sorbitol at 25 °C respectively. The pH profile of kcat/Ksorbitol for E154C decreased below an apparent pK of 9.1±0.3, reflecting a shift in pK by about +1.7–1.9 pH units compared with the corresponding pH profiles for GmXDH and sheep liver sorbitol dehydrogenase (termed slSDH). The difference in pK for profiles determined in 1H2O and 2H2O solvent was similar and unusually small for all three enzymes (≈+0.2 log units), suggesting that the observed pK in the binary enzyme–NAD+ complexes could be due to Zn2+-bound water. Under conditions eliminating their different pH-dependences, wild-type and mutant GmXDH displayed similar primary and solvent deuterium kinetic isotope effects of 1.7±0.2 (E154C, 1.7±0.1) and 1.9±0.3 (E154C, 2.4±0.2) on kcat/Ksorbitol respectively. Transient kinetic studies of NAD+ reduction and proton release during sorbitol oxidation by slSDH at pH 8.2 show that two protons are lost with a rate constant of 687±12 s−1 in the pre-steady state, which features a turnover of 0.9±0.1 enzyme equivalents as NADH was produced with a rate constant of 409±3 s−1. The

  10. Syntheses and molecular structures of novel Ru(II) complexes with bidentate benzimidazole based ligands and their catalytic efficiency for oxidation of benzyl alcohol

    Science.gov (United States)

    Dayan, Osman; Tercan, Melek; Özdemir, Namık

    2016-11-01

    Five bidentate ligands derived from quinoline-2-carboxylic acid, i.e. 2-(1H-benzimidazol-2-yl)quinoline (L1), 2-(1-benzyl-1H-benzimidazol-2-yl)quinoline (L2), 2-[1-(2,3,5,6-tetramethylbenzyl)-1H-benzimidazol-2-yl]quinoline (L3), 2-[1-(4-chlorobenzyl)-1H-benzimidazol-2-yl]quinoline (L4), and 2-[1-(4-methylbenzyl)-1H-benzimidazol-2-yl]quinoline (L5) were synthesized. Treatment of L1-5 with [RuCl2(p-cymene)]2 and KPF6 afforded six-coordinate piano-stool Ru(II) complexes, namely, [RuCl(L1)(p-cymene)]PF6 (C1), [RuCl(L2)(p-cymene)]PF6 (C2), [RuCl(L3)(p-cymene)]PF6 (C3), [RuCl(L4)(p-cymene)]PF6 (C4), and [RuCl(L5)(p-cymene)]PF6 (C5). Synthesized compounds were characterized with different techniques such as 1H and 13C NMR, FT-IR, and UV-vis spectroscopy. The solid state structure of L1 and C3 was confirmed by single-crystal X-ray diffraction analysis. The single crystal structure of C3 verified coordination of L3 to the Ru(II) center. The Ru(II) center has a pseudo-octahedral three legged piano stool geometry. The complexes C1-5 were tested as catalysts for the catalytic oxidation of benzyl alcohol to benzaldehyde in the presence of periodic acid (H5IO6) (Substrate/Catalyst/Oxidant = 1/0.01/0.5). The best result was obtained with C2 (3 h→90%).

  11. Highly efficient catalytic enantioselective Mannich reaction of malonates with N-tert-butoxycarbonyl imines by using Yb(OTf)3/pybox catalysts at room temperature.

    Science.gov (United States)

    Karimi, Babak; Jafari, Ehsan; Enders, Dieter

    2013-07-29

    Go Mannich! A highly efficient and enantioselective method for the direct asymmetric reaction of dibenzyl malonate with N-tert-butoxycarbonyl aldimines in the presence of Yb(OTf)3 and iPr-pybox complexes is described (see scheme; pybox = pyridine bisoxazoline).

  12. 催化膜和催化膜反应器:整合的高效和环保催化过程%Catalytic Membranes and Catalytic Membrane Reactors: An Integrated Approach to Catalytic Process with a High Efficiency and a Low Environmental Impact

    Institute of Scientific and Technical Information of China (English)

    Enrico DRIOLI; Enrica FONTANANOVA; Marcella BONCHIO; Mauro CARRARO; Martino GARDAN; Gianfranco SCORRANO

    2008-01-01

    The design of new heterogeneous photooxygenation systems able to employ visible light, oxygen, mild temperatures, and solvent with a low environmental impact has been investigated. In particular, the heterogenization of decatungstate (W10O4-32), a polyoxometalate with photocatalytic activity in oxidation reactions, has been carried out in polymeric membranes of polyvinylidenefluoride. The polymeric catalytic membranes prepared by phase inversion technique have been successfully applied in the aerobic mineralization of phenol in water, which was used as an example of organic pollutant. In order to evaluate the effect of the polymeric environment on the overall catalyst behavior, we have also heterogenized the decatungstate (opportunely functionalized) in perfluorinated membrane made of Hyflon. The photocatalytic composite membranes are characterized by different and tuneable properties depending on the nature of the polymeric micro-environment, in which the catalyst is confined. Moreover, the selective separation function of the membrane results in enhanced performance in comparison with homogeneous reactions.

  13. Variations in the Star Formation Efficiency of the Dense Molecular Gas across the Disks of Star-Forming Galaxies

    CERN Document Server

    Usero, Antonio; Walter, Fabian; Schruba, Andreas; García-Burillo, Santiago; Sandstrom, Karin; Bigiel, Frank; Brinks, Elias; Kramer, Carsten; Rosolowsky, Erik; Schuster, Karl-Friedrich; de Blok, W J G

    2015-01-01

    We present a new survey of HCN(1-0) emission, a tracer of dense molecular gas, focused on the little-explored regime of normal star-forming galaxy disks. Combining HCN, CO, and infrared (IR) emission, we investigate the role of dense gas in Star Formation (SF), finding systematic variations in both the apparent dense gas fraction and the apparent SF efficiency (SFE) of dense gas. The latter may be unexpected, given the popularity of gas density threshold models to explain SF scaling relations. We used the IRAM 30-m telescope to observe HCN(1-0) across 29 nearby disk galaxies whose CO(2-1) emission has previously been mapped by the HERACLES survey. Because our observations span a range of galactocentric radii, we are able to investigate the properties of the dense gas as a function of local conditions. We focus on how the IR/CO, HCN/CO, and IR/HCN ratios (observational cognates of the SFE, dense gas fraction, and dense gas SFE) depend on the stellar surface density and the molecular/atomic ratio. The HCN/CO ra...

  14. Requirements for Forming Efficient 3-D Charge Transport Pathway in Diketopyrrolopyrrole-Based Copolymers: Film Morphology vs Molecular Packing.

    Science.gov (United States)

    Lee, Gang-Young; Han, A-Reum; Kim, Taewan; Lee, Hae Rang; Oh, Joon Hak; Park, Taiho

    2016-05-18

    To achieve extremely high planarity and processability simultaneously, we have newly designed and synthesized copolymers composed of donor units of 2,2'-(2,5-dialkoxy-1,4-phenylene)dithieno[3,2-b]thiophene (TT-P-TT) and acceptor units of diketopyrrolopyrrole (DPP). These copolymers consist of a highly planar backbone due to intramolecular interactions. We have systematically investigated the effects of intermolecular interactions by controlling the side chain bulkiness on the polymer thin-film morphologies, packing structures, and charge transport. The thin-film microstructures of the copolymers are found to be critically dependent upon subtle changes in the intermolecular interactions, and charge transport dynamics of the copolymer based field-effect transistors (FETs) has been investigated by in-depth structure-property relationship study. Although the size of the fibrillar structures increases as the bulkiness of the side chains in the copolymer increases, the copolymer with the smallest side chain shows remarkably high charge carrier mobility. Our findings reveal the requirement for forming efficient 3-D charge transport pathway and highlight the importance of the molecular packing and interdomain connectivity, rather than the crystalline domain size. The results obtained herein demonstrate the importance of tailoring the side chain bulkiness and provide new insights into the molecular design for high-performance polymer semiconductors. PMID:27117671

  15. Efficient C-O and C-N bond forming cross-coupling reactions catalyzed by core-shell structured Cu/Cu2O nanowires

    KAUST Repository

    Elshewy, Ahmed M.

    2013-12-01

    Oxygen and Nitrogen containing compounds are of utmost importance due to their interesting and diverse biological activities. The construction of the C-O and C–N bonds is of significance as it opens avenues for the introduction of ether and amine linkages in organic molecules. Despite significant advancements in this field, the construction of C-O and C–N bonds is still a major challenge for organic chemists, due to the involvement of harsh reaction conditions or the use of expensive catalysts or ligands in many cases. Thus, it is a challenge to develop alternative, milder, cheaper and more reproducible methodologies for the construction of these types of bonds. Herein, we introduce a new efficient ligand free catalytic system for C-O and C-N bond formation reactions.

  16. Variations in the Star Formation Efficiency of the Dense Molecular Gas across the Disks of Star-forming Galaxies

    Science.gov (United States)

    Usero, Antonio; Leroy, Adam K.; Walter, Fabian; Schruba, Andreas; García-Burillo, Santiago; Sandstrom, Karin; Bigiel, Frank; Brinks, Elias; Kramer, Carsten; Rosolowsky, Erik; Schuster, Karl-Friedrich; de Blok, W. J. G.

    2015-10-01

    We present a new survey of HCN(1–0) emission, a tracer of dense molecular gas, focused on the little-explored regime of normal star-forming galaxy disks. Combining HCN, CO, and infrared (IR) emission, we investigate the role of dense gas in star formation, finding systematic variations in both the apparent dense gas fraction (traced by the HCN-to-CO ratio) and the apparent star formation efficiency of dense gas (traced by the IR-to-HCN ratio). The latter may be unexpected, given the recent popularity of gas density threshold models to explain star formation scaling relations. Our survey used the IRAM 30 m telescope to observe HCN(1–0), CO(1–0), and several other emission lines across 29 nearby disk galaxies whose CO(2–1) emission has previously been mapped by the HERACLES survey. We detected HCN in 48 out of 62 observed positions. Because our observations achieve a typical resolution of ∼1.5 kpc and span a range of galaxies and galactocentric radii (56% lie at {r}{gal}\\gt 1 kpc), we are able to investigate the properties of the dense gas as a function of local conditions in a galaxy disk. We focus on how the ratios IR-to-CO, HCN-to-CO, and IR-to-HCN (observational cognates of the star formation efficiency, dense gas fraction, and dense gas star formation efficiency) depend on the stellar surface density, {{{Σ }}}{star}, and the molecular-to-atomic gas ratio, {{{Σ }}}{mol}/{{{Σ }}}{atom}. The HCN-to-CO ratio is low, often ∼1/30, and correlates tightly with both the molecular-to-atomic ratio and the stellar mass surface density across a range of 2.1 dex (factor of ≈125) in both parameters. Thus for the assumption of fixed CO-to-H2 and HCN-to-dense gas conversion factors, the dense gas fraction depends strongly on location in the disk, being higher in the high surface density, highly molecular parts of galaxies. At the same time, the IR-to-HCN ratio (closely related to the star formation efficiency of dense molecular gas) decreases systematically

  17. Identification of catalytic sites for oxygen reduction and oxygen evolution in N-doped graphene materials: Development of highly efficient metal-free bifunctional electrocatalyst

    OpenAIRE

    Yang, Hong Bin; Miao, Jianwei; Hung, Sung-Fu; Chen, Jiazang; Tao, Hua Bing; Wang, Xizu; Zhang, Liping; Chen, Rong; Gao, Jiajian; Chen, Hao Ming; Dai, Liming; Liu, Bin

    2016-01-01

    Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are critical to renewable energy conversion and storage technologies. Heteroatom-doped carbon nanomaterials have been reported to be efficient metal-free electrocatalysts for ORR in fuel cells for energy conversion, as well as ORR and OER in metal-air batteries for energy storage. We reported that metal-free three-dimensional (3D) graphene nanoribbon networks (N-GRW) doped with nitrogen exhibited superb bifunctional electroca...

  18. Catalytic Ozonation of Phenolic Wastewater: Identification and Toxicity of Intermediates

    Directory of Open Access Journals (Sweden)

    Mahdi Farzadkia

    2014-01-01

    Full Text Available A new strategy in catalytic ozonation removal method for degradation and detoxification of phenol from industrial wastewater was investigated. Magnetic carbon nanocomposite, as a novel catalyst, was synthesized and then used in the catalytic ozonation process (COP and the effects of operational conditions such as initial pH, reaction time, and initial concentration of phenol on the degradation efficiency and the toxicity assay have been investigated. The results showed that the highest catalytic potential was achieved at optimal neutral pH and the removal efficiency of phenol and COD is 98.5% and 69.8%, respectively. First-order modeling demonstrated that the reactions were dependent on the initial concentration of phenol, with kinetic constants varying from 0.038 min−1  ([phenol]o = 1500 mg/L to 1.273 min−1 ([phenol]o = 50 mg/L. Bioassay analysis showed that phenol was highly toxic to Daphnia magna (LC50 96 h=5.6 mg/L. Comparison of toxicity units (TU of row wastewater (36.01 and the treated effluent showed that TU value, after slightly increasing in the first steps of ozonation for construction of more toxic intermediates, severely reduced at the end of reaction (2.23. Thus, COP was able to effectively remove the toxicity of intermediates which were formed during the chemical oxidation of phenolic wastewaters.

  19. A parallel offline CFD and closed-form approximation strategy for computationally efficient analysis of complex fluid flows

    Science.gov (United States)

    Allphin, Devin

    Computational fluid dynamics (CFD) solution approximations for complex fluid flow problems have become a common and powerful engineering analysis technique. These tools, though qualitatively useful, remain limited in practice by their underlying inverse relationship between simulation accuracy and overall computational expense. While a great volume of research has focused on remedying these issues inherent to CFD, one traditionally overlooked area of resource reduction for engineering analysis concerns the basic definition and determination of functional relationships for the studied fluid flow variables. This artificial relationship-building technique, called meta-modeling or surrogate/offline approximation, uses design of experiments (DOE) theory to efficiently approximate non-physical coupling between the variables of interest in a fluid flow analysis problem. By mathematically approximating these variables, DOE methods can effectively reduce the required quantity of CFD simulations, freeing computational resources for other analytical focuses. An idealized interpretation of a fluid flow problem can also be employed to create suitably accurate approximations of fluid flow variables for the purposes of engineering analysis. When used in parallel with a meta-modeling approximation, a closed-form approximation can provide useful feedback concerning proper construction, suitability, or even necessity of an offline approximation tool. It also provides a short-circuit pathway for further reducing the overall computational demands of a fluid flow analysis, again freeing resources for otherwise unsuitable resource expenditures. To validate these inferences, a design optimization problem was presented requiring the inexpensive estimation of aerodynamic forces applied to a valve operating on a simulated piston-cylinder heat engine. The determination of these forces was to be found using parallel surrogate and exact approximation methods, thus evidencing the comparative

  20. Update: An efficient synthesis of poly(ethylene glycol)-supported iron(II) porphyrin using a click reaction and its application for the catalytic olefination of aldehydes

    KAUST Repository

    Chinnusamy, Tamilselvi R.

    2012-05-09

    The facile synthesis of polyethylene glycol (PEG)-immobilized iron(II) porphyrin using a copper-catalyzed azide-alkyne [3+2] cycloaddition "click" reaction is reported. The prepared complex 5 (PEG-C 51H 39FeN 7O) was found to be an efficient catalyst for the selective olefination of aldehydes with ethyl diazoacetate in the presence of triphenylphosphine, and afforded excellent olefin yields with high (E) selectivities. The PEG-supported catalyst 5 was readily recovered by precipitation and filtration, and was recycled through ten runs without significant activity loss. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Catalytic functionalization of indoles in a new dimension.

    Science.gov (United States)

    Bandini, Marco; Eichholzer, Astrid

    2009-01-01

    140 years ago Adolf von Baeyer proposed the structure of a heteroaromatic compound which revolutionized organic and medical chemistry: indole. After more than a century, indole itself and the complexity of naturally occurring indole derivatives continue to inspire and influence developments in synthetic chemistry. In particular, the ubiquitous presence of indole rings in pharmaceuticals, agrochemicals, and functional materials are testament to the ever increasing interest in the design of mild and efficient synthetic routes to functionalized indole derivatives. This Review emphasizes the achievements in the selective catalytic functionalization of indoles (C-C bond-forming processes) over the last four years.

  2. Identification of catalytic sites for oxygen reduction and oxygen evolution in N-doped graphene materials: Development of highly efficient metal-free bifunctional electrocatalyst.

    Science.gov (United States)

    Yang, Hong Bin; Miao, Jianwei; Hung, Sung-Fu; Chen, Jiazang; Tao, Hua Bing; Wang, Xizu; Zhang, Liping; Chen, Rong; Gao, Jiajian; Chen, Hao Ming; Dai, Liming; Liu, Bin

    2016-04-01

    Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are critical to renewable energy conversion and storage technologies. Heteroatom-doped carbon nanomaterials have been reported to be efficient metal-free electrocatalysts for ORR in fuel cells for energy conversion, as well as ORR and OER in metal-air batteries for energy storage. We reported that metal-free three-dimensional (3D) graphene nanoribbon networks (N-GRW) doped with nitrogen exhibited superb bifunctional electrocatalytic activities for both ORR and OER, with an excellent stability in alkaline electrolytes (for example, KOH). For the first time, it was experimentally demonstrated that the electron-donating quaternary N sites were responsible for ORR, whereas the electron-withdrawing pyridinic N moieties in N-GRW served as active sites for OER. The unique 3D nanoarchitecture provided a high density of the ORR and OER active sites and facilitated the electrolyte and electron transports. As a result, the as-prepared N-GRW holds great potential as a low-cost, highly efficient air cathode in rechargeable metal-air batteries. Rechargeable zinc-air batteries with the N-GRW air electrode in a two-electrode configuration exhibited an open-circuit voltage of 1.46 V, a specific capacity of 873 mAh g(-1), and a peak power density of 65 mW cm(-2), which could be continuously charged and discharged with an excellent cycling stability. Our work should open up new avenues for the development of various carbon-based metal-free bifunctional electrocatalysts of practical significance. PMID:27152333

  3. The influence of anionic ligands on stereoisomerism of Ru carbenes and their importance to efficiency and selectivity of catalytic olefin metathesis reactions.

    Science.gov (United States)

    Torker, Sebastian; Khan, R Kashif M; Hoveyda, Amir H

    2014-03-01

    Investigations detailed herein provide insight regarding the mechanism of stereochemical inversion of stereogenic-at-Ru carbene complexes through a nonolefin metathesis-based polytopal rearrangement pathway. Computational analyses (DFT) reveal that there are two key factors that generate sufficient energy barriers that are responsible for the possibility of isolation and characterization of high-energy, but kinetically stable, intermediates: (1) donor-donor interactions that involve the anionic ligands and the strongly electron donating carbene groups and (2) dipolar effects arising from the syn relationship between the anionic groups (iodide and phenoxide). We demonstrate that a Brønsted acid lowers barriers to facilitate isomerization, and that the positive influence of a proton source is the result of its ability to diminish the repulsive electronic interactions originating from the anionic ligands. The implications of the present studies regarding a more sophisticated knowledge of the role of anionic units on the efficiency of Ru-catalyzed olefin metathesis reactions are discussed. The electronic basis for the increased facility with which allylic alcohols participate in olefin metathesis processes will be presented as well. Finally, we illustrate how a better understanding of the role of anionic ligands has served as the basis for successful design of Ru-based Z-selective catalysts for alkene metathesis.

  4. The influence of anionic ligands on stereoisomerism of Ru carbenes and their importance to efficiency and selectivity of catalytic olefin metathesis reactions.

    Science.gov (United States)

    Torker, Sebastian; Khan, R Kashif M; Hoveyda, Amir H

    2014-03-01

    Investigations detailed herein provide insight regarding the mechanism of stereochemical inversion of stereogenic-at-Ru carbene complexes through a nonolefin metathesis-based polytopal rearrangement pathway. Computational analyses (DFT) reveal that there are two key factors that generate sufficient energy barriers that are responsible for the possibility of isolation and characterization of high-energy, but kinetically stable, intermediates: (1) donor-donor interactions that involve the anionic ligands and the strongly electron donating carbene groups and (2) dipolar effects arising from the syn relationship between the anionic groups (iodide and phenoxide). We demonstrate that a Brønsted acid lowers barriers to facilitate isomerization, and that the positive influence of a proton source is the result of its ability to diminish the repulsive electronic interactions originating from the anionic ligands. The implications of the present studies regarding a more sophisticated knowledge of the role of anionic units on the efficiency of Ru-catalyzed olefin metathesis reactions are discussed. The electronic basis for the increased facility with which allylic alcohols participate in olefin metathesis processes will be presented as well. Finally, we illustrate how a better understanding of the role of anionic ligands has served as the basis for successful design of Ru-based Z-selective catalysts for alkene metathesis. PMID:24533571

  5. Catalytic cracking of lignites

    Energy Technology Data Exchange (ETDEWEB)

    Seitz, M.; Nowak, S.; Naegler, T.; Zimmermann, J. [Hochschule Merseburg (Germany); Welscher, J.; Schwieger, W. [Erlangen-Nuernberg Univ. (Germany); Hahn, T. [Halle-Wittenberg Univ., Halle (Germany)

    2013-11-01

    A most important factor for the chemical industry is the availability of cheap raw materials. As the oil price of crude oil is rising alternative feedstocks like coal are coming into focus. This work, the catalytic cracking of lignite is part of the alliance ibi (innovative Braunkohlenintegration) to use lignite as a raw material to produce chemicals. With this new one step process without an input of external hydrogen, mostly propylene, butenes and aromatics and char are formed. The product yield depends on manifold process parameters. The use of acid catalysts (zeolites like MFI) shows the highest amount of the desired products. Hydrogen rich lignites with a molar H/C ratio of > 1 are to be favoured. Due to primary cracking and secondary reactions the ratio between catalyst and lignite, temperature and residence time are the most important parameter to control the product distribution. Experiments at 500 C in a discontinuous rotary kiln reactor show yields up to 32 wt-% of hydrocarbons per lignite (maf - moisture and ash free) and 43 wt-% char, which can be gasified. Particularly, the yields of propylene and butenes as main products can be enhanced four times to about 8 wt-% by the use of catalysts while the tar yield decreases. In order to develop this innovative process catalyst systems fixed on beads were developed for an easy separation and regeneration of the used catalyst from the formed char. (orig.)

  6. Double catalytic effect of (PhNH32CuCl4 in a novel, highly efficient synthesis of 2-oxo and thioxo-1,2,3,4-tetra-hydopyrimidines

    Directory of Open Access Journals (Sweden)

    Janković Nenad

    2015-01-01

    Full Text Available An innovative route for the construction of 2-oxo and thioxo-1,2,3,4-tetrahydropyrimidines was delineated through a multicomponent reaction under Biginelli conditions, starting from different aromatic aldehydes, β-ketoesters and urea or thiourea. Proper choice of copper complex (PhNH32CuCl4, as a novel homogeneous catalyst, enables facile, efficient, and inexpensive reaction under mild experimental conditions. Moreover, we present the first application of this complex salts in organic synthesis ever. The obtained products are of high purity, and can be easily isolated from the reaction mixture in good to excellent yields. Also, compared to the classical Biginelli reaction conditions, the present method has the advantages in higher yields and experimental and work-up simplicity. To illustrate the joint catalytic action of the Cu2+ and phenylammonium ions, two key steps of Biginelli reaction were examined using the M06 functional. [Projekat Ministarstva nauke Republike Srbije, br. 172011 i br. 172016

  7. Method and apparatus for a catalytic firebox reactor

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Lance L. (North Haven, CT); Etemad, Shahrokh (Trumbull, CT); Ulkarim, Hasan (Hamden, CT); Castaldi, Marco J. (Bridgeport, CT); Pfefferle, William C. (Madison, CT)

    2001-01-01

    A catalytic firebox reactor employing an exothermic catalytic reaction channel and multiple cooling conduits for creating a partially reacted fuel/oxidant mixture. An oxidation catalyst is deposited on the walls forming the boundary between the multiple cooling conduits and the exothermic catalytic reaction channel, on the side of the walls facing the exothermic catalytic reaction channel. This configuration allows the oxidation catalyst to be backside cooled by any fluid passing through the cooling conduits. The heat of reaction is added to both the fluid in the exothermic catalytic reaction channel and the fluid passing through the cooling conduits. After discharge of the fluids from the exothermic catalytic reaction channel, the fluids mix to create a single combined flow. A further innovation in the reactor incorporates geometric changes in the exothermic catalytic reaction channel to provide streamwise variation of the velocity of the fluids in the reactor.

  8. Catalytic distillation structure

    Science.gov (United States)

    Smith, Jr., Lawrence A.

    1984-01-01

    Catalytic distillation structure for use in reaction distillation columns, a providing reaction sites and distillation structure and consisting of a catalyst component and a resilient component intimately associated therewith. The resilient component has at least about 70 volume % open space and being present with the catalyst component in an amount such that the catalytic distillation structure consist of at least 10 volume % open space.

  9. An iron–oxygen intermediate formed during the catalytic cycle of cysteine dioxygenase† †Electronic supplementary information (ESI) available: Experimental and computational details. See DOI: 10.1039/c6cc03904a Click here for additional data file.

    Science.gov (United States)

    Tchesnokov, E. P.; Faponle, A. S.; Davies, C. G.; Quesne, M. G.; Turner, R.; Fellner, M.; Souness, R. J.; Wilbanks, S. M.

    2016-01-01

    Cysteine dioxygenase is a key enzyme in the breakdown of cysteine, but its mechanism remains controversial. A combination of spectroscopic and computational studies provides the first evidence of a short-lived intermediate in the catalytic cycle. The intermediate decays within 20 ms and has absorption maxima at 500 and 640 nm. PMID:27297454

  10. Catalytic gasification of biomass

    Science.gov (United States)

    Robertus, R. J.; Mudge, L. K.; Sealock, L. J., Jr.; Mitchell, D. H.; Weber, S. L.

    1981-12-01

    Methane and methanol synthesis gas can be produced by steam gasification of biomass in the presence of appropriate catalysts. This concept is to use catalysts in a fluidized bed reactor which is heated indirectly. The objective is to determine the technical and economic feasibility of the concept. Technically the concept has been demonstrated on a 50 lb per hr scale. Potential advantages over conventional processes include: no oxygen plant is needed, little tar is produced so gas and water treatment are simplified, and yields and efficiencies are greater than obtained by conventional gasification. Economic studies for a plant processing 2000 T/per day dry wood show that the cost of methanol from wood by catalytic gasification is competitive with the current price of methanol. Similar studies show the cost of methane from wood is competitive with projected future costs of synthetic natural gas. When the plant capacity is decreased to 200 T per day dry wood, neither product is very attractive in today's market.

  11. Catalytic production of biodiesel

    Energy Technology Data Exchange (ETDEWEB)

    Theilgaard Madsen, A.

    2011-07-01

    The focus of this thesis is the catalytic production of diesel from biomass, especially emphasising catalytic conversion of waste vegetable oils and fats. In chapter 1 an introduction to biofuels and a review on different catalytic methods for diesel production from biomass is given. Two of these methods have been used industrially for a number of years already, namely the transesterification (and esterification) of oils and fats with methanol to form fatty acid methyl esters (FAME), and the hydrodeoxygenation (HDO) of fats and oils to form straight-chain alkanes. Other possible routes to diesel include upgrading and deoxygenation of pyrolysis oils or aqueous sludge wastes, condensations and reductions of sugars in aqueous phase (aqueous-phase reforming, APR) for monofunctional hydrocarbons, and gasification of any type of biomass followed by Fischer-Tropsch-synthesis for alkane biofuels. These methods have not yet been industrialised, but may be more promising due to the larger abundance of their potential feedstocks, especially waste feedstocks. Chapter 2 deals with formation of FAME from waste fats and oils. A range of acidic catalysts were tested in a model fat mixture of methanol, lauric acid and trioctanoin. Sulphonic acid-functionalised ionic liquids showed extremely fast convertion of lauric acid to methyl laurate, and trioctanoate was converted to methyl octanoate within 24 h. A catalyst based on a sulphonated carbon-matrix made by pyrolysing (or carbonising) carbohydrates, so-called sulphonated pyrolysed sucrose (SPS), was optimised further. No systematic dependency on pyrolysis and sulphonation conditions could be obtained, however, with respect to esterification activity, but high activity was obtained in the model fat mixture. SPS impregnated on opel-cell Al{sub 2}O{sub 3} and microporous SiO{sub 2} (ISPS) was much less active in the esterification than the original SPS powder due to low loading and thereby low number of strongly acidic sites on the

  12. Thermodynamics of catalytic nanoparticle morphology

    Science.gov (United States)

    Zwolak, Michael; Sharma, Renu; Lin, Pin Ann

    Metallic nanoparticles are an important class of industrial catalysts. The variability of their properties and the environment in which they act, from their chemical nature & surface modification to their dispersion and support, allows their performance to be optimized for many chemical processes useful in, e.g., energy applications and other areas. Their large surface area to volume ratio, as well as varying sizes and faceting, in particular, makes them an efficient source for catalytically active sites. These characteristics of nanoparticles - i.e., their morphology - can often display intriguing behavior as a catalytic process progresses. We develop a thermodynamic model of nanoparticle morphology, one that captures the competition of surface energy with other interactions, to predict structural changes during catalytic processes. Comparing the model to environmental transmission electron microscope images of nickel nanoparticles during carbon nanotube (and other product) growth demonstrates that nickel deformation in response to the nanotube growth is due to a favorable interaction with carbon. Moreover, this deformation is halted due to insufficient volume of the particles. We will discuss the factors that influence morphology and also how the model can be used to extract interaction strengths from experimental observations.

  13. Catalytic hydrolysis for the degradation of organophosphorus pesticides in water

    International Nuclear Information System (INIS)

    The kinetic studies of catalytic hydrolysis revealed that the concentration of two kinds of organophosphorus pesticides (omethoate and methidathion) in solution apparently decays according to the second order reaction. It was found that the rate constant value was highest at strong acidic conditions and it continued to decrease as the pH of the solution was increased. At basic conditions the rate constant value decreased to minimum. Manganese dioxide under acidic conditions converted into Mn/sup 2+/ ions and then these ions in water form hexaaquomanganese (II) ion. This hexaaquomanganese (II ion then adsorbed itself on the S or O atom of the organophosphorus compound and thus weakens the bond between P-S. This reaction facilitated the attack of H/sub 2/O or OH/sup -/ ion and thus enhanced the efficiency of hydrolysis. It was studied that methidathion hydrolyzed more efficiently than omethoate The rate constants of catalytic hydrolysis were increased with increasing the amount of MnO/sub 2/. It was found that the pesticides had undergone adsorption on catalyst in the first few minutes and there was the rapid drop of total phosphorus concentration. The decrease of total phosphorus adsorption with increasing pH was also observed. After the addition of alkaline earth metal cations (Ca/sup 2+/ and Mg/sup 2+/) along with magnesium, the enhancement in the efficiency of hydrolysis at near neutral conditions occurred. (author)

  14. Visualization of murine intranasal dosing efficiency using luminescent Francisella tularensis: effect of instillation volume and form of anesthesia.

    Directory of Open Access Journals (Sweden)

    Mark A Miller

    Full Text Available Intranasal instillation is a widely used procedure for pneumonic delivery of drugs, vaccine candidates, or infectious agents into the respiratory tract of research mice. However, there is a paucity of published literature describing the efficiency of this delivery technique. In this report we have used the murine model of tularemia, with Francisella tularensis live vaccine strain (FTLVS infection, to evaluate the efficiency of pneumonic delivery via intranasal dosing performed either with differing instillation volumes or different types of anesthesia. FTLVS was rendered luminescent via transformation with a reporter plasmid that constitutively expressed the Photorhabdus luminescens lux operon from a Francisella promoter. We then used an IVIS Spectrum whole animal imaging system to visualize FT dissemination at various time points following intranasal instillation. We found that instillation of FT in a dose volume of 10 µl routinely resulted in infection of the upper airways but failed to initiate infection of the pulmonary compartment. Efficient delivery of FT into the lungs via intranasal instillation required a dose volume of 50 µl or more. These studies also demonstrated that intranasal instillation was significantly more efficient for pneumonic delivery of FTLVS in mice that had been anesthetized with inhaled (isoflurane vs. parenteral (ketamine/xylazine anesthesia. The collective results underscore the need for researchers to consider both the dose volume and the anesthesia type when either performing pneumonic delivery via intranasal instillation, or when comparing studies that employed this technique.

  15. Efficient Estimation of Extreme Non-linear Roll Motions using the First-order Reliability Method (FORM)

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher

    2007-01-01

    In on-board decision support systems efficient procedures are needed for real-time estimation of the maximum ship responses to be expected within the next few hours, given on-line information on the sea state and user defined ranges of possible headings and speeds. For linear responses standard...

  16. Including lateral interactions into microkinetic models of catalytic reactions

    DEFF Research Database (Denmark)

    Hellman, Anders; Honkala, Johanna Karoliina

    2007-01-01

    In many catalytic reactions lateral interactions between adsorbates are believed to have a strong influence on the reaction rates. We apply a microkinetic model to explore the effect of lateral interactions and how to efficiently take them into account in a simple catalytic reaction. Three...

  17. Improving the personnel policy of organization and increasing its efficiency by forming skills and competencies of staff

    Directory of Open Access Journals (Sweden)

    Yankovskaya Veronika

    2016-03-01

    Full Text Available The article presents the results of the diagnostic of problems in the personnel policy of the local organization. The analysis of the skills and competencies, procedures and methods of implementation of human resources policy is done; methods of evaluating the effectiveness of human resource management are developed and tested. Measures to improve the efficiency of human resources policy of the organization are deliberated and recommended.

  18. Improving the personnel policy of organization and increasing its efficiency by forming skills and competencies of staff

    OpenAIRE

    Янковская, Вероника Владимировна

    2016-01-01

    The article presents the results of the diagnostic of problems in the personnel policy of the local organization. The analysis of the skills and competencies, procedures and methods of implementation of human resources policy is done; methods of evaluating the effectiveness of human resource management are developed and tested. Measures to improve the efficiency of human resources policy of the organization are deliberated and recommended.

  19. Forming heterojunction: an effective strategy to enhance the photocatalytic efficiency of a new metal-free organic photocatalyst for water splitting

    Science.gov (United States)

    Li, Hengshuai; Hu, Haiquan; Bao, Chunjiang; Guo, Feng; Zhang, Xiaoming; Liu, Xiaobiao; Hua, Juan; Tan, Jie; Wang, Aizhu; Zhou, Hongcai; Yang, Bo; Qu, Yuanyuan; Liu, Xiangdong

    2016-07-01

    Photocatalytic water splitting is a new technology for the conversion and utilization of solar energy and has a potential prospect. One important aspect of enhancing the photocatalytic efficiency is how to improve the electron-hole separation. Up to now, there is still no ideal strategy to improve the electron-hole separation. In this article, for metal-free organic photocatalysts, we propose a good strategy- forming heterojunction, which can effectively improve the electron-hole separation. We provide a metal-free organic photocatalyst g-C12N7H3 for water splitting. The stability of g-C12N7H3 has been investigated, the X-ray diffraction spectra has been simulated. Using first-principles calculations, we have systematically studied the electronic structure, band edge alignment, and optical properties for the g-C12N7H3. The results demonstrated that g-C12N7H3 is a new organocatalyst material for water splitting. In order to enhance the photocatalytic efficiency, we provided four strategies, i.e., multilayer stacking, raising N atoms, forming g-C9N10/g-C12N7H3 heterojunction, and forming graphene/g-C12N7H3 heterojunction. Our research is expected to stimulate experimentalists to further study novel 2D metal-free organic materials as visible light photocatalysts. Our strategies, especially forming heterojunction, will substantially help to enhance the photocatalytic efficiency of metal-free organic photocatalyst.

  20. Platinum Iron Intermetallic Nanoparticles Supported on Carbon Formed In Situ by High-Pressure Pyrolysis for Efficient Oxygen Reduction

    DEFF Research Database (Denmark)

    Hu, Yang; Jensen, Jens Oluf; Zhang, Wei;

    2016-01-01

    treatment of the catalyst. During these preliminary syntheses, we found that a portion of the PtFe nanoparticles is buried in the in situ formed carbon phase, which limits Pt utilization in the catalyst and results in a mass-specific activity equivalent to the commercial Pt/C catalyst. Moreover...

  1. Catalytic asymmetric synthesis of mycocerosic acid

    NARCIS (Netherlands)

    ter Horst, B.; Feringa, B.L.; J. Minnaard, A.

    2007-01-01

    The first catalytic asymmetric total synthesis of mycocerosic acid was achieved via the application of iterative enantioselective 1,4-addition reactions and allows for the efficient construction of 1,3-polymethyl arrays with full stereocontrol; further exemplified by the synthesis of tetramethyl-dec

  2. Catalytic distillation process

    Science.gov (United States)

    Smith, Jr., Lawrence A.

    1982-01-01

    A method for conducting chemical reactions and fractionation of the reaction mixture comprising feeding reactants to a distillation column reactor into a feed zone and concurrently contacting the reactants with a fixed bed catalytic packing to concurrently carry out the reaction and fractionate the reaction mixture. For example, a method for preparing methyl tertiary butyl ether in high purity from a mixed feed stream of isobutene and normal butene comprising feeding the mixed feed stream to a distillation column reactor into a feed zone at the lower end of a distillation reaction zone, and methanol into the upper end of said distillation reaction zone, which is packed with a properly supported cationic ion exchange resin, contacting the C.sub.4 feed and methanol with the catalytic distillation packing to react methanol and isobutene, and concurrently fractionating the ether from the column below the catalytic zone and removing normal butene overhead above the catalytic zone.

  3. Catalytic Functions of Standards

    NARCIS (Netherlands)

    K. Blind (Knut)

    2009-01-01

    textabstractThe three different areas and the examples have illustrated several catalytic functions of standards for innovation. First, the standardisation process reduces the time to market of inventions, research results and innovative technologies. Second, standards themselves promote the diffusi

  4. Temperature effects on nitrogen cycling and nitrate removal-production efficiency in bed form-induced hyporheic zones

    Science.gov (United States)

    Zheng, Lizhi; Cardenas, M. Bayani; Wang, Lichun

    2016-04-01

    Hyporheic flow in aquatic sediment controls solute and heat transport thereby mediating the fate of nutrients and contaminants, dissolved oxygen, and temperature in the hyporheic zone (HZ). We conducted a series of numerical simulations of hyporheic processes within a dune with different uniform temperatures, coupling turbulent open channel fluid flow, porous fluid flow, and reactive solute transport to study the temperature dependence of nitrogen source/sink functionality and its efficiency. Two cases were considered: a polluted stream and a pristine stream. Sensitivity analysis was performed to investigate the influence of stream water [NO3-]/[NH4+]. The simulations showed that in both cases warmer temperatures resulted in shallower denitrification zones and oxic-anoxic zone boundaries, but the trend of net denitrification rate and nitrate removal or production efficiency of the HZ for these two cases differed. For both cases, at high [NO3-]/[NH4+], the HZ functioned as a NO3- sink with the nitrate removal efficiency increasing with temperature. But at low [NO3-]/[NH4+] for the polluted stream, the HZ is a NO3- sink at low temperature but then switches to a NO3- source at warmer temperatures. For the pristine stream case, the HZ was always a NO3- source, with the NO3- production efficiency increasing monotonically with temperature. In addition, although the interfacial fluid flux expectedly increased with increasing temperature due to decreasing fluid viscosity, the total nitrate flux into the HZ did not follow this trend. This is because when HZ nitrification is high, uniformly elevated [NO3-] lowers dispersive fluxes into the HZ. We found that there are numerous confounding and interacting factors that combined to lead to the final temperature dependence of N transformation reaction rates. Although the temperature effect on the rate constant can be considered as the dominant factor, simply using the Arrhenius equation to predict the reaction rate would lead to

  5. The Star Formation Rate Efficiency of Neutral Atomic-dominated Hydrogen Gas in the Outskirts of Star Forming Galaxies from z~1 to z~3

    CERN Document Server

    Rafelski, Marc; Fumagalli, Michele; Neeleman, Marcel; Teplitz, Harry I; Grogin, Norman; Koekemoer, Anton M; Scarlata, Claudia

    2016-01-01

    Current observational evidence suggests that the star formation rate (SFR) efficiency of neutral atomic hydrogen gas measured in Damped Ly-alpha Systems (DLAs) at z~3 is more than 10 times lower than predicted by the Kennicutt-Schmidt (KS) relation. To understand the origin of this deficit, and to investigate possible evolution with redshift and galaxy properties, we measure the SFR efficiency of atomic gas at z~1, z~2, and z~3 around star-forming galaxies. We use new robust photometric redshifts in the Hubble Ultra Deep Field to create galaxy stacks in these three redshift bins, and measure the SFR efficiency by combining DLA absorber statistics with the observed rest-frame UV emission in the galaxies' outskirts. We find that the SFR efficiency of HI gas at z>1 is ~1-3% of that predicted by the KS relation. Contrary to simulations and models that predict a reduced SFR efficiency with decreasing metallicity and thus with increasing redshift, we find no significant evolution in the SFR efficiency with redshift...

  6. Hybrid Arrangements as a Form of Ecological Modernization: The Case of the US Energy Efficiency Conservation Block Grants

    Directory of Open Access Journals (Sweden)

    Anya M. Galli

    2016-01-01

    Full Text Available How are environmental policy goals implemented and sustained in the context of political stagnation surrounding national climate policies in the United States? In this paper, we discuss Ecological Modernization Theory as a tool for understanding the complexity of climate governance at the sub-national level. In particular, we explore the emergence of hybrid governance arrangements during the local implementation of federal energy efficiency programs in US cities. We analyze the formation and advancement of programs associated with one effort to establish a sub-national low carbon energy policy: the Energy Efficiency and Conservation Block Grant (EECBG program administered by the US Department of Energy. Our findings highlight the diverse range of partnerships between state, private, and civil society actors that emerged through this program and point to some of the challenges associated with collaborative climate governance initiatives at the city level. Although some programs reflected ecologically modern outcomes, other cities were constrained in their ability to move beyond the status quo due to the demands of state bureaucracies and the challenges associated with inconsistent funding. We find that these programs cultivated hybrid arrangements in an effort to sustain the projects following the termination of federal grant funding. Overall, hybrid governance plays an important role in the implementation and long-term sustainability of climate-related policies.

  7. Spectroscopic properties and the catalytic activity of new organo-lead supramolecular coordination polymer containing quinoxaline

    Science.gov (United States)

    Etaiw, Safaa El-din H.; Abdou, Safaa N.

    2015-01-01

    The 3D-supramolecular coordination polymer (SCP) 3∞[ Cu2(CN)3(Me3Pb)(qox)], 1, as the first example of the CuCN SCP containing the (Me3Pb) fragment, was explored to investigate its catalytic and photo-catalytic activities. The structure of 1 contains two chemically identical but crystallographically different [Cu2(CN)3ṡMe3Pbṡqox]2 units with four Cu(I) sites assuming distorted TP-3 geometry. Two non-linear chains of equal abundance are formed producing corrugated parallel chains which are connected laterally by quinoxaline creating 2D-layers which are arranged parallel in an (AB⋯AB⋯AB)n fashion forming 3D-network. IR, mass, electronic absorption and fluorescence spectra are also investigated. The SCP 1 is diamagnetic and exhibits good catalytic and photo-catalytic activities for the degradation of methylene blue (MB). The reaction is first order with respect to MB dye. The irradiation of the reaction with UV-light enhanced the rate of MB mineralization. The efficiency of recycled the 1 and the mechanism of degradation of MB dye were investigated.

  8. Testing the Semi-Strong Form efficiency to differentiate stock returns between Islamic and Non-Islamic firms: Empirical evidence using dividend announcement from Malaysia.

    OpenAIRE

    Saya, Muhammad Mujtuba

    2015-01-01

    This dissertation conducts an event study in the specific area of Efficient Market Hypothesis (EMH). It concentrates on the semi-strong form and focuses on exploring the impact of dividend announcements on share prices’ of Malaysian stock market (Bursa Malaysia). Further, it commences a comparison of Islamic (Shariah) compliant stocks and non-Islamic compliant stocks. A sample of 60 companies (30 Shariah and 30 Non-Shraiah compliant) were selected from the main board of Bursa Malaysia. An eve...

  9. A HIGHER EFFICIENCY OF CONVERTING GAS TO STARS PUSHES GALAXIES AT z ∼ 1.6 WELL ABOVE THE STAR-FORMING MAIN SEQUENCE

    Energy Technology Data Exchange (ETDEWEB)

    Silverman, J. D.; Rujopakarn, W. [Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Daddi, E.; Liu, D. [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, Irfu/Service d’Astrophysique, CEA Saclay (France); Rodighiero, G. [Dipartimento di Fisica e Astronomia, Universita di Padova, vicolo Osservatorio, 3, I-35122 Padova (Italy); Sargent, M. [Astronomy Centre, Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom); Renzini, A. [Instituto Nazionale de Astrofisica, Osservatorio Astronomico di Padova, v.co dell’Osservatorio 5, I-35122 Padova (Italy); Feruglio, C. [IRAM—Institut de RadioAstronomie Millimétrique, 300 rue de la Piscine, F-38406 Saint Martin d’Hères (France); Kashino, D. [Division of Particle and Astrophysical Science, Graduate School of Science, Nagoya University, Nagoya 464-8602 (Japan); Sanders, D. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Kartaltepe, J. [National Optical Astronomy Observatory, 950 N. Cherry Avenue, Tucson, AZ 85719 (United States); Nagao, T. [Graduate School of Science and Engineering, Ehime University, 2-5 Bunkyo-cho, Matsuyama 790-8577 (Japan); Arimoto, N. [Subaru Telescope, 650 North A’ohoku Place, Hilo, HI-96720 (United States); Berta, S.; Lutz, D. [Max-Planck-Institut für extraterrestrische Physik, D-84571 Garching (Germany); Béthermin, M. [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching (Germany); Koekemoer, A., E-mail: john.silverman@ipmu.jp [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD, 21218 (United States); and others

    2015-10-20

    Local starbursts have a higher efficiency of converting gas into stars, as compared to typical star-forming galaxies at a given stellar mass, possibly indicative of different modes of star formation. With the peak epoch of galaxy formation occurring at z > 1, it remains to be established whether such an efficient mode of star formation is occurring at high redshift. To address this issue, we measure the molecular gas content of seven high-redshift (z ∼ 1.6) starburst galaxies with the Atacama Large Millimeter/submillimeter Array and IRAM/Plateau de Bure Interferometer. Our targets are selected from the sample of Herschel far-infrared-detected galaxies having star formation rates (∼300–800 M{sub ⊙} yr{sup −1}) elevated (≳4×) above the star-forming main sequence (MS) and included in the FMOS-COSMOS near-infrared spectroscopic survey of star-forming galaxies at z ∼ 1.6 with Subaru. We detect CO emission in all cases at high levels of significance, indicative of high gas fractions (∼30%–50%). Even more compelling, we firmly establish with a clean and systematic selection that starbursts, identified as MS outliers, at high redshift generally have a lower ratio of CO to total infrared luminosity as compared to typical MS star-forming galaxies, although with a smaller offset than expected based on past studies of local starbursts. We put forward a hypothesis that there exists a continuous increase in star formation efficiency with elevation from the MS with galaxy mergers as a possible physical driver. Along with a heightened star formation efficiency, our high-redshift sample is similar in other respects to local starbursts, such as being metal rich and having a higher ionization state of the interstellar medium.

  10. Catalytic ignition of light hydrocarbons

    Institute of Scientific and Technical Information of China (English)

    K. L. Hohn; C.-C. Huang; C. Cao

    2009-01-01

    Catalytic ignition refers to phenomenon where sufficient energy is released from a catalytic reaction to maintain further reaction without additional extemai heating. This phenomenon is important in the development of catalytic combustion and catalytic partial oxidation processes, both of which have received extensive attention in recent years. In addition, catalytic ignition studies provide experimental data which can be used to test theoretical hydrocarbon oxidation models. For these reasons, catalytic ignition has been frequently studied. This review summarizes the experimental methods used to study catalytic ignition of light hydrocarbons and describes the experimental and theoretical results obtained related to catalytic ignition. The role of catalyst metal, fuel and fuel concentration, and catalyst state in catalytic ignition are examined, and some conclusions are drawn on the mechanism of catalytic ignition.

  11. Catalytic aerobic oxidation of bio-renewable chemicals

    DEFF Research Database (Denmark)

    Gorbanev, Yury

    -free conditions. Moreover, a detailed study on the performance and stability of the ruthenium hydroxide catalysts on magnesium-containing supports under reaction conditions was conducted. The aerobic oxidation of HMF to form another value-added chemical, 2,5-diformylfuran (DFF), was also investigated......, EDS, XRF and other methods. Supported gold and ruthenium hydroxide catalyst systems were explored for the aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDA), a potential polymer building block for the plastic industry, or its dimethyl ester (FDMC). High product......Ox deposited on various metal oxides. Furthermore, this thesis presents the results of the catalytic aerobic oxidative degradation of higher alcohols over supported ruthenium hydroxide catalysts. A very efficient oxidative cleavage of vic-diols to form respective acids was also shown under examined conditions...

  12. Mutational analysis of a ras catalytic domain

    DEFF Research Database (Denmark)

    Willumsen, B M; Papageorge, A G; Kung, H F;

    1986-01-01

    We used linker insertion-deletion mutagenesis to study the catalytic domain of the Harvey murine sarcoma virus v-rasH transforming protein, which is closely related to the cellular rasH protein. The mutants displayed a wide range of in vitro biological activity, from those that induced focal...... transformation of NIH 3T3 cells with approximately the same efficiency as the wild-type v-rasH gene to those that failed to induce any detectable morphologic changes. Correlation of transforming activity with the location of the mutations enabled us to identify three nonoverlapping segments within the catalytic...

  13. Heterogeneous Catalytic Ozonization of Sulfosalicylic Acid

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper describes the potential of heterogeneous catalytic ozonization of sulfo-salicylic acid (SSal). It was found that catalytic ozonization in the presence of Mn-Zr-O (a modified manganese dioxide supported on silica gel) had significantly enhanced the removal rate (72%) of total organic carbon (TOC) compared with that of ozonization alone (19%). The efficient removal rate of TOC was probably due to increasing the adsorption ability of catalyst and accelerating decomposition of ozone to produce more powerful oxidants than ozone.

  14. 上海股票市场半强式有效性实证分析%Positive analysis on semistrong-form efficiency of Shanghai stock market

    Institute of Scientific and Technical Information of China (English)

    刘琨; 李凯; 张永平

    2001-01-01

    Efficiency of stock Market refers to one that the price of stocks in market responses to the new information. It indicates the mature degree of stock market. Effective market can be divided into weak-form market,semistrong-form market and strong-form market. By positively researching on 30 companies on Shanghai stock market,the authors concludes that Shanghai stock market is not semistrong-form efficiency at present.%股票市场的效率性指的是股票市场中股票价格对新信息的反应效率,它是股票市场成熟程度的表现。有效率的市场分为弱式有效市场、半强式有效市场和强式有效市场。通过对上海股市的30家上市公司进行实证研究,得出的结论是:目前上海股票市场非半强式有效。

  15. Loss of allosteric control but retention of the bifunctional catalytic competence of a fusion protein formed by excision of 260 base pairs from the 3' terminus of pheA from Erwinia herbicola.

    OpenAIRE

    Xia, T.; Zhao, G.; Jensen, R A

    1992-01-01

    A bifunctional protein denoted as the P protein and encoded by pheA is widely present in purple gram-negative bacteria. This P protein carries catalytic domains that specify chorismate mutase (CM-P) and prephenate dehydratase. The instability of a recombinant plasmid carrying a pheA insert cloned from Erwinia herbicola resulted in a loss of 260 bp plus the TAA stop codon from the 3' terminus of pheA. The plasmid carrying the truncated pheA gene (denoted pheA*) was able to complement an Escher...

  16. Performance characterization of a hydrogen catalytic heater.

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Terry Alan; Kanouff, Michael P.

    2010-04-01

    This report describes the performance of a high efficiency, compact heater that uses the catalytic oxidation of hydrogen to provide heat to the GM Hydrogen Storage Demonstration System. The heater was designed to transfer up to 30 kW of heat from the catalytic reaction to a circulating heat transfer fluid. The fluid then transfers the heat to one or more of the four hydrogen storage modules that make up the Demonstration System to drive off the chemically bound hydrogen. The heater consists of three main parts: (1) the reactor, (2) the gas heat recuperator, and (3) oil and gas flow distribution manifolds. The reactor and recuperator are integrated, compact, finned-plate heat exchangers to maximize heat transfer efficiency and minimize mass and volume. Detailed, three-dimensional, multi-physics computational models were used to design and optimize the system. At full power the heater was able to catalytically combust a 10% hydrogen/air mixture flowing at over 80 cubic feet per minute and transfer 30 kW of heat to a 30 gallon per minute flow of oil over a temperature range from 100 C to 220 C. The total efficiency of the catalytic heater, defined as the heat transferred to the oil divided by the inlet hydrogen chemical energy, was characterized and methods for improvement were investigated.

  17. Antibodies That Efficiently Form Hexamers upon Antigen Binding Can Induce Complement-Dependent Cytotoxicity under Complement-Limiting Conditions

    Science.gov (United States)

    Cook, Erika M.; Lindorfer, Margaret A.; van der Horst, Hilma; Oostindie, Simone; Beurskens, Frank J.; Schuurman, Janine; Zent, Clive S.; Burack, Richard; Parren, Paul W. H. I.

    2016-01-01

    Recently, we demonstrated that IgG Abs can organize into ordered hexamers after binding their cognate Ags expressed on cell surfaces. This process is dependent on Fc:Fc interactions, which promote C1q binding, the first step in classical pathway complement activation. We went on to engineer point mutations that stimulated IgG hexamer formation and complement-dependent cytotoxicity (CDC). The hexamer formation–enhanced (HexaBody) CD20 and CD38 mAbs support faster, more robust CDC than their wild-type counterparts. To further investigate the CDC potential of these mAbs, we used flow cytometry, high-resolution digital imaging, and four-color confocal microscopy to examine their activity against B cell lines and primary chronic lymphocytic leukemia cells in sera depleted of single complement components. We also examined the CDC activity of alemtuzumab (anti-CD52) and mAb W6/32 (anti-HLA), which bind at high density to cells and promote substantial complement activation. Although we observed little CDC for mAb-opsonized cells reacted with sera depleted of early complement components, we were surprised to discover that the Hexabody mAbs, as well as ALM and W6/32, were all quite effective at promoting CDC in sera depleted of individual complement components C6 to C9. However, neutralization studies conducted with an anti-C9 mAb verified that C9 is required for CDC activity against cell lines. These highly effective complement-activating mAbs efficiently focus activated complement components on the cell, including C3b and C9, and promote CDC with a very low threshold of MAC binding, thus providing additional insight into their enhanced efficacy in promoting CDC. PMID:27474078

  18. Catalytic nanoarchitectonics for environmentally compatible energy generation

    Directory of Open Access Journals (Sweden)

    Hideki Abe

    2016-01-01

    Full Text Available Environmentally compatible energy management is one of the biggest challenges of the 21st century. Low-temperature conversion of chemical to electrical energy is of particular importance to minimize the impact to the environment while sustaining the consumptive economy. In this review, we shed light on one of the most versatile energy-conversion technologies: heterogeneous catalysts. We establish the integrity of structural tailoring in heterogeneous catalysts at different scales in the context of an emerging paradigm in materials science: catalytic nanoarchitectonics. Fundamental backgrounds of energy-conversion catalysis are first provided together with a perspective through state-of-the-art energy-conversion catalysis including catalytic exhaust remediation, fuel-cell electrocatalysis and photosynthesis of solar fuels. Finally, the future evolution of catalytic nanoarchitectonics is overviewed: possible combinations of heterogeneous catalysts, organic molecules and even enzymes to realize reaction-selective, highly efficient and long-life energy conversion technologies which will meet the challenge we face.

  19. High-pressure catalytic and thermal cracking of polyethylene

    Energy Technology Data Exchange (ETDEWEB)

    Mosio-Mosiewski, Jan; Warzala, Marek; Morawski, Ireneusz; Dobrzanski, Tadeusz [Institute of Heavy Organic Synthesis, ul. Energetykow 9, 47-225 Kedzierzyn-Kozle (Poland)

    2007-04-15

    The thermal cracking and catalytic cracking processes of low-density polyethylene were studied in a closed autoclave. The compositions of gaseous and liquid products were analysed by means of GC/FID and GS/MS chromatographic methods. The fractional composition of liquid products was found by distillation. Increased temperature of PE depolymerisation process increases the production of gaseous products and low-boiling liquid compounds; more aromatic hydrocarbons are formed instead of alkenes. When a lower temperature and longer time are adopted for the process to reach the assumed conversion, more straight chained hydrocarbons are produced. The acidic aluminosilicate catalyst yields more low-boiling liquid fractions, more isoalkanes and more aromatics. The neutral alumina is favourable for the production of alkenes and vacuum gas oil fraction in comparison to a non-catalytic process. The Ni-Mo/Al{sub 2}O{sub 3} catalyst is efficient in hydrogenation of depolymerisation products. The reaction products contain only saturated compounds then and no aromatics are formed. (author)

  20. Catalytic conversion of light alkanes

    Energy Technology Data Exchange (ETDEWEB)

    Lyons, J.E.

    1992-06-30

    The second Quarterly Report of 1992 on the Catalytic Conversion of Light Alkanes reviews the work done between April 1, 1992 and June 31, 1992 on the Cooperative Agreement. The mission of this work is to devise a new catalyst which can be used in a simple economic process to convert the light alkanes in natural gas to oxygenate products that can either be used as clean-burning, high octane liquid fuels, as fuel components or as precursors to liquid hydrocarbon uwspomdon fuel. During the past quarter we have continued to design, prepare, characterize and test novel catalysts for the mild selective reaction of light hydrocarbons with air or oxygen to produce alcohols directly. These catalysts are designed to form active metal oxo (MO) species and to be uniquely active for the homolytic cleavage of the carbon-hydrogen bonds in light alkanes producing intermediates which can form alcohols. We continue to investigate three molecular environments for the active catalytic species that we are trying to generate: electron-deficient macrocycles (PHASE I), polyoxometallates (PHASE II), and regular oxidic lattices including zeolites and related structures as well as other molecular surface structures having metal oxo groups (PHASE I).

  1. Catalytic coherence transformations

    Science.gov (United States)

    Bu, Kaifeng; Singh, Uttam; Wu, Junde

    2016-04-01

    Catalytic coherence transformations allow the otherwise impossible state transformations using only incoherent operations with the aid of an auxiliary system with finite coherence that is not being consumed in any way. Here we find the necessary and sufficient conditions for the deterministic and stochastic catalytic coherence transformations between a pair of pure quantum states. In particular, we show that the simultaneous decrease of a family of Rényi entropies of the diagonal parts of the states under consideration is a necessary and sufficient condition for the deterministic catalytic coherence transformations. Similarly, for stochastic catalytic coherence transformations we find the necessary and sufficient conditions for achieving a higher optimal probability of conversion. We thus completely characterize the coherence transformations among pure quantum states under incoherent operations. We give numerous examples to elaborate our results. We also explore the possibility of the same system acting as a catalyst for itself and find that indeed self-catalysis is possible. Further, for the cases where no catalytic coherence transformation is possible we provide entanglement-assisted coherence transformations and find the necessary and sufficient conditions for such transformations.

  2. A higher efficiency of converting gas to stars push galaxies at z ~ 1.6 well above the star-forming main sequence

    CERN Document Server

    Silverman, J D; Rodighiero, G; Rujopakarn, W; Sargent, M; Renzini, A; Liu, D; Feruglio, C; Kashino, D; Sanders, D; Kartaltepe, J; Nagao, T; Arimoto, N; Berta, S; Bethermin, M; Lutz, D; Magdis, G; Mancini, C; Onodera, M; Zamorani, G

    2015-01-01

    Local starbursts have a higher efficiency of converting gas into stars, as compared to typical star-forming galaxies at a given stellar mass, possibly indicative of different modes of star formation. With the peak epoch of galaxy formation occurring at z > 1, it remains to be established whether such an efficient mode of star formation is occurring at high-redshift. To address this issue, we measure the CO molecular gas content of seven high-redshift starburst galaxies with ALMA and IRAM/PdBI. Our sample is selected from the FMOS-COSMOS near-infrared spectroscopic survey of star-forming galaxies at z ~ 1.6 with Subaru. All galaxies have star formation rates (~300-800 Msolar/yr) elevated, by at least four times, above the star-forming main sequence. We detect CO emission in all cases at high significance, indicative of plentiful gas supplies (f_gas ~ 30-50%). Even more compelling, we firmly establish for the first time that starbursts at high redshift systematically have a lower ratio of CO to total infrared l...

  3. Selective catalytic oxidation of ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Leppaelahti, J.; Koljonen, T. [VTT Energy, Espoo (Finland)

    1996-12-31

    In the combustion of fossil fuels, the principal source of nitrogen oxides is nitrogen bound in the fuel structure. In gasification, a large part of fuel nitrogen forms NH{sub 3}, which may form nitrogen oxides during gas combustion. If NH{sub 3} and other nitrogen species could be removed from hot gas, the NO emission could be considerably reduced. However, relatively little attention has been paid to finding new means of removing nitrogen compounds from the hot gasification gas. The possibility of selectively oxidizing NH{sub 3} to N{sub 2} in the hot gasification has been studied at VTT Energy. The largest NH{sub 3} reductions have been achieved by catalytic oxidation on aluminium oxides. (author) (4 refs.)

  4. Construction of a novel cationic polymeric liposomes formed from PEGlated octadecyl-quaternized lysine modified chitosan/cholesterol for enhancing storage stability and cellular uptake efficiency.

    Science.gov (United States)

    Wang, Hanjie; Zhao, Peiqi; Liang, Xiaofei; Song, Tao; Gong, Xiaoqun; Niu, Ruifang; Chang, Jin

    2010-08-15

    The design and construction of delivery vectors with high stability and effective cellular uptake efficiency is very important. In this study, a novel polymeric liposomes (PLs) formed from PEGlated octadecyl-quaternized lysine modified chitosan (OQLCS) and cholesterol with higher size stability and cellular uptake efficiency has been synthesized successfully. Compared to conventional liposomes (CLs; phosphatidyl choline/cholesterol), the calcein-loaded PLs exhibited a multi-lamellar structure with homogenous size diameter (200 nm) and high calcein encapsulation efficiency (about 92%). PLs could be stored at different temperature (25, 4, and -20 degrees C) and different medium (deionized water, phosphate-buffered saline, and human plasma solution) for up to 4 weeks without significant size change. The spectrophotometer fluorometry analysis and the flow cytometry analysis indicated that in comparison with CL, PLs with positive zeta potential facilitates the uptake of calcein by MCF-7 tumor cells. The data suggests that PLs may provide a new method to overcome the stability and enhance the uptake efficiency of CLs. PMID:20506161

  5. Targeting chromosomal sites with locked nucleic acid-modified triplex-forming oligonucleotides: study of efficiency dependence on DNA nuclear environment

    OpenAIRE

    Brunet, Erika; Corgnali, Maddalena; Cannata, Fabio; Perrouault, Loïc; Giovannangeli, Carine

    2006-01-01

    Triplex-forming oligonucleotides (TFOs) are synthetic DNA code-reading molecules that have been demonstrated to function to some extent in chromatin within cell nuclei. Here we have investigated the impact of DNA nuclear environment on the efficiency of TFO binding. For this study we have used locked nucleic acid-containing TFOs (TFO/LNAs) and we report the development of a rapid PCR-based method to quantify triplex formation. We have first compared triplex formation on genes located at diffe...

  6. Selective catalytic oxidation of H2S over iron oxide supported on alumina-intercalated Laponite clay catalysts

    International Nuclear Information System (INIS)

    Graphical abstract: The catalytic reaction and deactivation mechanisms for H2S selective oxidation over Fe/Al-Lap catalysts are shown in the illustration. The catalytic reaction follows Mars–van Krevelen mechanism. Moreover, the interaction between iron oxide and alumina, the strong acidity of the catalysts and the well dispersion of iron oxide improve the catalytic performance efficiently. Meanwhile, the catalyst deactivation is mainly due to the formation of Fe2(SO4)3 and elemental sulfur deposits on the surface. -- Highlights: • Fe/Al-Lap catalysts with mesoporous structure were synthesized. • Iron oxide mainly exists in form of isolate Fe3+ in an oxidic environment. •Fe/Al-Lap catalysts show high catalytic activities at low temperature. •The high catalytic activities are ascribed to the interaction between iron oxide and alumina. •The formed Fe2(SO4)3 and elemental sulfur deposits on surface cause catalyst deactivation. -- Abstract: A series of iron oxide supported on alumina-intercalated clay catalysts (named Fe/Al-Lap catalysts) with mesoporous structure and high specific surface area were prepared. The structural and chemical properties were studied by nitrogen sorption isotherms, X-ray diffraction (XRD), UV–vis diffuse reflectance spectra (UV–vis DRS), X-ray photoelectron spectra (XPS), Fourier transform infrared spectroscopy (FTIR), H2 temperature-programmed reduction (H2-TPR) and NH3 temperature-programmed desorption (NH3-TPD) techniques. It was realized that iron oxide mainly existed in the form of isolated Fe3+ in an oxidic environment. Fe/Al-Lap catalysts showed high catalytic activities in the temperature range of 120–200 °C without the presence of excessive O2. This can be attributed to the interaction between iron oxide and alumina, which improve the redox property of Fe3+ efficiently. In addition, the strong acidity of catalysts and good dispersion of iron oxide were also beneficial to oxidation reaction. Among them, 7% Fe

  7. Catalytic Phosphination and Arsination

    Institute of Scientific and Technical Information of China (English)

    Kwong Fuk Yee; Chan Kin Shing

    2004-01-01

    The catalytic, user-friendly phosphination and arsination of aryl halides and triflates by triphenylphosphine and triphenylarsine using palladium catalysts have provided a facile synthesis of functionalized aryl phosphines and arsines in neutral media. Modification of the cynaoarisne yielded optically active N, As ligands which will be screened in various asymmetric catalysis.

  8. Vapour Treatment Method Against Other Pyro- and Hydrometallurgical Processes Applied to Recover Platinum From Used Auto Catalytic Converters

    Institute of Scientific and Technical Information of China (English)

    Agnieszka FORNALCZYK; Mariola SATERNUS

    2013-01-01

    Today more and more cars are produced every year.All of them have to be equipped with catalytic converters,the main role of which is to obtain substances harmless to the environment instead of exhausted gases.Catalytic converters contain platinum group metals (PGM) especially platinum,palladium and rhodium.The price of these metals and their increasing demand are the reasons why today it is necessary to recycle used auto catalytic converters.There are many available methods of recovering PGM metals from them,especially platinum.These methods used mainly hydrometallurgical processes; however pyrometallurgical ones become more and more popular.The article presents results of the research mainly concerning pyrometallurgical processes.Two groups of research were carried out.In the first one different metals such as lead,magnesium and copper were used as a metal collector.During the tests,platinum went to those metals forming an alloy.In other research metal vapours were blown through catalytic converter carrier (grinded or whole).In the tests metals such as calcium,magnesium,cadmium and zinc were applied.As a result white or grey powder (metal plus platinum) was obtained.The tables present results of the research.Processing parameters and conclusions are also shown.To compare efficiency of pyrometallurgical and hydrometallurgical methods catalytic converter carrier and samples of copper with platinum obtained from pyrometallurgical method were solved in aqua regia,mixture of aqua regia and fluoric acid.

  9. Removal of formaldehyde over MnxCe1-xO2 catalysts: Thermal catalytic oxidation versus ozone catalytic oxidation

    Institute of Scientific and Technical Information of China (English)

    Jia Wei Li; Kuan Lun Pan; Sheng Jen Yu; Shaw Yi Yan; Moo Been Chang

    2014-01-01

    MnxCe1-xO2 (x:0.3-0.9) prepared by Pechini method was used as a catalyst for the thermal catalytic oxidation of formaldehyde (HCHO).At x =0.3 and 0.5,most of the manganese was incorporated in the fluorite structure of CeO2 to form a solid solution.The catalytic activity was best at x =0.5,at which the temperature of 100% removal rate is the lowest (270℃).The temperature for 100% removal of HCHO oxidation is reduced by approximately 40℃ by loading 5 wt.% CuOx into Mn0.5Ce0.5O2.With ozone catalytic oxidation,HCHO (61 ppm) in gas stream was completely oxidized by adding 506 ppm O3 over Mn0.5Ce0.5O2 catalyst with a GHSV (gas hourly space velocity) of 10,000 hr-1 at 25℃.The effect of the molar ratio of O3 to HCHO was also investigated.As O3/HCHO ratio was increased from 3 to 8,the removal efficiency of HCHO was increased from 83.3% to 100%.With O3/HCHO ratio of 8,the mineralization efficiency of HCHO to CO2 was 86.1%.At 25℃,the p-type oxide semiconductor (Mn0.5Ce0.5O2) exhibited an excellent ozone decomposition efficiency of 99.2%,which significantly exceeded that of n-type oxide semiconductors such as TiO2,which had a low ozone decomposition efficiency (9.81%).At a GHSV of 10,000 hr-1,[O3]/[HCHO] =3 and temperature of 25℃,a high HCHO removal efficiency (≥81.2%) was maintained throughout the durability test of 80 hr,indicating the long-term stability of the catalyst for HCHO removal.

  10. Self-formed grain boundary healing layer for highly efficient CH3 NH3 PbI3 perovskite solar cells

    Science.gov (United States)

    Son, Dae-Yong; Lee, Jin-Wook; Choi, Yung Ji; Jang, In-Hyuk; Lee, Seonhee; Yoo, Pil J.; Shin, Hyunjung; Ahn, Namyoung; Choi, Mansoo; Kim, Dongho; Park, Nam-Gyu

    2016-07-01

    Perovskite solar cells have attracted significant research efforts due to their remarkable performance, with certified power conversion efficiency now reaching 22%. Solution-processed perovskite thin films are polycrystalline, and grain boundaries are thought to be responsible for causing recombination and trapping of charge carriers. Here we report an effective and reproducible way of treating grain boundaries in CH3NH3PbI3 films deposited by means of a Lewis acid–base adduct approach. We show by high-resolution transmission electron microscopy lattice images that adding 6 mol% excess CH3NH3I to the precursor solution resulted in a CH3NH3I layer forming at the grain boundaries. This layer is responsible for suppressing non-radiative recombination and improving hole and electron extraction at the grain boundaries by forming highly ionic-conducting pathways. We report an average power conversion efficiency of 20.1% over 50 cells (best cell at 20.4%) together with significantly reduced current–voltage hysteresis achieved by this grain boundary healing process.

  11. First-principles investigation on the electronic efficiency and binding energy of the contacts formed by graphene and poly-aromatic hydrocarbon anchoring groups

    International Nuclear Information System (INIS)

    The electronic efficiency and binding energy of contacts formed between graphene electrodes and poly-aromatic hydrocarbon (PAH) anchoring groups have been investigated by the non-equilibrium Green’s function formalism combined with density functional theory. Our calculations show that PAH molecules always bind in the interior and at the edge of graphene in the AB stacking manner, and that the binding energy increases following the increase of the number of carbon and hydrogen atoms constituting the PAH molecule. When we move to analyzing the electronic transport properties of molecular junctions with a six-carbon alkyne chain as the central molecule, the electronic efficiency of the graphene-PAH contacts is found to depend on the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the corresponding PAH anchoring group, rather than its size. To be specific, the smaller is the HOMO-LUMO gap of the PAH anchoring group, the higher is the electronic efficiency of the graphene-PAH contact. Although the HOMO-LUMO gap of a PAH molecule depends on its specific configuration, PAH molecules with similar atomic structures show a decreasing trend for their HOMO-LUMO gap as the number of fused benzene rings increases. Therefore, graphene-conjugated molecule-graphene junctions with high-binding and high-conducting graphene-PAH contacts can be realized by choosing appropriate PAH anchor groups with a large area and a small HOMO-LUMO gap

  12. SCR-catalytic converter technology using urea for industrial and thermal power plants. SCR-Katalysatortechnik mit Harnstoff fuer Industrie- und Heizkraftwerke

    Energy Technology Data Exchange (ETDEWEB)

    Hartenstein, A. (H und H Innotech GmbH (Switzerland)); Mayer, A. (H und H Innotech GmbH (Switzerland))

    1994-01-01

    The subjects are dealt with in 6 chapters: 1. Fuels, pollutants, prices 2. fields of application of catalytic converter systems 3. system description of the SCR catalytic converter plant using area 4. catalytic converter reactor and applications 5. efficiencies of catalytic converter plants 6. examples and profitability. (HW)

  13. Kinetically controlled E-selective catalytic olefin metathesis.

    Science.gov (United States)

    Nguyen, Thach T; Koh, Ming Joo; Shen, Xiao; Romiti, Filippo; Schrock, Richard R; Hoveyda, Amir H

    2016-04-29

    A major shortcoming in olefin metathesis, a chemical process that is central to research in several branches of chemistry, is the lack of efficient methods that kinetically favor E isomers in the product distribution. Here we show that kinetically E-selective cross-metathesis reactions may be designed to generate thermodynamically disfavored alkenyl chlorides and fluorides in high yield and with exceptional stereoselectivity. With 1.0 to 5.0 mole % of a molybdenum-based catalyst, which may be delivered in the form of air- and moisture-stable paraffin pellets, reactions typically proceed to completion within 4 hours at ambient temperature. Many isomerically pure E-alkenyl chlorides, applicable to catalytic cross-coupling transformations and found in biologically active entities, thus become easily and directly accessible. Similarly, E-alkenyl fluorides can be synthesized from simpler compounds or more complex molecules. PMID:27126041

  14. Kinetically controlled E-selective catalytic olefin metathesis.

    Science.gov (United States)

    Nguyen, Thach T; Koh, Ming Joo; Shen, Xiao; Romiti, Filippo; Schrock, Richard R; Hoveyda, Amir H

    2016-04-29

    A major shortcoming in olefin metathesis, a chemical process that is central to research in several branches of chemistry, is the lack of efficient methods that kinetically favor E isomers in the product distribution. Here we show that kinetically E-selective cross-metathesis reactions may be designed to generate thermodynamically disfavored alkenyl chlorides and fluorides in high yield and with exceptional stereoselectivity. With 1.0 to 5.0 mole % of a molybdenum-based catalyst, which may be delivered in the form of air- and moisture-stable paraffin pellets, reactions typically proceed to completion within 4 hours at ambient temperature. Many isomerically pure E-alkenyl chlorides, applicable to catalytic cross-coupling transformations and found in biologically active entities, thus become easily and directly accessible. Similarly, E-alkenyl fluorides can be synthesized from simpler compounds or more complex molecules.

  15. Preparation and electro-catalytic oxidation efficiency of different bipolar particle electrodes%不同复极性粒子电极的制备及电催化氧化效能

    Institute of Scientific and Technical Information of China (English)

    魏金枝; 胡琴; 张少平

    2015-01-01

    分别以高阻抗的瓷环粒子、陶瓷粒子、陶土粒子及黏土粒子为载体,负载 Sb 掺杂 SnO2活性催化组分制备粒子电极,并通过SEM、EDS、XRD等表征手段对其形貌及结构进行研究,筛选出瓷环粒子、陶土粒子.并以农药氧化乐果为目标物,对所筛选的粒子电极进行电催化氧化效能的对比研究.结果表明,负载Sb掺杂SnO2的瓷环粒子电极表面积相对较大,具有丰富的孔结构,且具有一定的导电性.在所构建的三维电极体系中处理COD为900mg/L左右的氧化乐果废水,当支持电解质无水Na2SO4浓度为0.1mol/L、激发槽电压为13V时,处理 120min 后,在瓷环粒子三维电极体系中废水 COD 去除率比陶土粒子三维电极体系高 9.58%,比二维电极体系高25.7%;相应的能耗分别低2.9kW?h/kg(COD)和7.9kW?h/kg(COD).%In this work,different high-impedance carriers of ceramic ring particle,ceramic particle, pottery particle and clay particle loaded with activated component of Sb doped SnO2were applied to prepare various particle electrodes. The micrograph and crystal structure of the particle electrodes were characterized by the scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDS) and X-ray diffraction(XRD) to screen out the ceramic ring particle and the pottery particle. Furthermore,the comparison of the electro-catalytic oxidation efficiency among the selected particle electrodes was made with omethoate pesticide as target pollutant. The ceramic ring particle electrodes exhibited a larger specific surface area,more abundant pore structure and certain electrical conductivity. Omethoate waste water with COD concentration of 900mg/L was treated for 120min under the conditions of supporting electrolyte concentration of 0.1mol/L,excitation cell voltage of 13V,the treatment time of 120min. Compared to the three-dimensional electrode system with pottery particle and the two-dimensional electrode system,the system with

  16. Heterogeneous catalytic materials solid state chemistry, surface chemistry and catalytic behaviour

    CERN Document Server

    Busca, Guido

    2014-01-01

    Heterogeneous Catalytic Materials discusses experimental methods and the latest developments in three areas of research: heterogeneous catalysis; surface chemistry; and the chemistry of catalysts. Catalytic materials are those solids that allow the chemical reaction to occur efficiently and cost-effectively. This book provides you with all necessary information to synthesize, characterize, and relate the properties of a catalyst to its behavior, enabling you to select the appropriate catalyst for the process and reactor system. Oxides (used both as catalysts and as supports for cata

  17. Catalytic Decomposition of Methylene Chloride by Sulfated Titania Catalysts

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Catalytic decomposition of methylene chloride in air below 300℃ was studied.Sulfated titania was very effective in converting 959ppm methylene chloride selectively to CO,CO2 and HCl.Complete decomposition of methylene chloride was achieved at low temperature(275℃).It was found that the acidic property of catalyst was a determinant factor for the catalytic activity.The presence of water vapor in the feed stream remarkably reduced the catalytic activity,which could be due to the blockage of acidic sites on the surface of catalyst by water molecules.A bifunctional catalyst comprising copper oxide was developed to improve the selectivity of catalytic oxidation,which indicated that copper oxide can promote the deep oxidation of methylene chloride.The crystal form of TiO2 imposes an important influence upon the catalytic oxidation.

  18. Structural and functional characterization of mature forms of metalloprotease E495 from Arctic sea-ice bacterium Pseudoalteromonas sp. SM495.

    Directory of Open Access Journals (Sweden)

    Hai-Lun He

    Full Text Available E495 is the most abundant protease secreted by the Arctic sea-ice bacterium Pseudoalteromonas sp. SM495. As a thermolysin family metalloprotease, E495 was found to have multiple active forms in the culture of strain SM495. E495-M (containing only the catalytic domain and E495-M-C1 (containing the catalytic domain and one PPC domain were two stable mature forms, and E495-M-C1-C2 (containing the catalytic domain and two PPC domains might be an intermediate. Compared to E495-M, E495-M-C1 had similar affinity and catalytic efficiency to oligopeptides, but higher affinity and catalytic efficiency to proteins. The PPC domains from E495 were expressed as GST-fused proteins. Both of the recombinant PPC domains were shown to have binding ability to proteins C-phycocyanin and casein, and domain PPC1 had higher affinity to C-phycocyanin than domain PPC2. These results indicated that the domain PPC1 in E495-M-C1 could be helpful in binding protein substrate, and therefore, improving the catalytic efficiency. Site-directed mutagenesis on the PPC domains showed that the conserved polar and aromatic residues, D26, D28, Y30, Y/W65, in the PPC domains played key roles in protein binding. Our study may shed light on the mechanism of organic nitrogen degradation in the Arctic sea ice.

  19. Enhanced propylene production in FCC by novel catalytic materials

    Energy Technology Data Exchange (ETDEWEB)

    Kelkar, C.P.; Harris, D.; Xu, M.; Fu, J. [BASF Catalyst LLC, Iselin, NJ (United States)

    2007-07-01

    Fluid catalytic cracking is expected to increasingly supply the additional incremental requirements for propylene. The most efficient route to increase propylene yield from an FCC unit is through the use of medium pore zeolites such as ZSM-5. ZSM-5 zeolite cracks near linear olefins in the gasoline range to LPG olefins such as propylene and butylenes. This paper will describe catalytic approaches to increase gasoline range olefins and the chemistry of ZSM-5 to crack those olefins. The paper will also describe novel catalytic materials designed to increase propylene. (orig.)

  20. Methods of using structures including catalytic materials disposed within porous zeolite materials to synthesize hydrocarbons

    Science.gov (United States)

    Rollins, Harry W.; Petkovic, Lucia M.; Ginosar, Daniel M.

    2011-02-01

    Catalytic structures include a catalytic material disposed within a zeolite material. The catalytic material may be capable of catalyzing a formation of methanol from carbon monoxide and/or carbon dioxide, and the zeolite material may be capable of catalyzing a formation of hydrocarbon molecules from methanol. The catalytic material may include copper and zinc oxide. The zeolite material may include a first plurality of pores substantially defined by a crystal structure of the zeolite material and a second plurality of pores dispersed throughout the zeolite material. Systems for synthesizing hydrocarbon molecules also include catalytic structures. Methods for synthesizing hydrocarbon molecules include contacting hydrogen and at least one of carbon monoxide and carbon dioxide with such catalytic structures. Catalytic structures are fabricated by forming a zeolite material at least partially around a template structure, removing the template structure, and introducing a catalytic material into the zeolite material.

  1. A catalytic cracking process

    Energy Technology Data Exchange (ETDEWEB)

    Degnan, T.F.; Helton, T.E.

    1995-07-20

    Heavy oils are subjected to catalytic cracking in the absence of added hydrogen using a catalyst containing a zeolite having the structure of ZSM-12 and a large-pore crystalline zeolite having a Constraint Index less than about 1. The process is able to effect a bulk conversion of the oil at the same time yielding a higher octane gasoline and increased light olefin content. (author)

  2. Supercritical CO{sub 2} mediated synthesis and catalytic activity of graphene/Pd nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Lulu [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeoungbuk 712-749 (Korea, Republic of); Nguyen, Van Hoa [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeoungbuk 712-749 (Korea, Republic of); Department of Chemistry, Nha Trang University, 2 Nguyen Dinh Chieu, Nha Trang (Viet Nam); Shim, Jae-Jin, E-mail: jjshim@yu.ac.kr [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeoungbuk 712-749 (Korea, Republic of)

    2015-11-15

    Highlights: • RGO/Pd composite was efficiently prepared via a facile method in supercritical CO{sub 2}. • Graphene sheets were coated uniformly with Pd nanoparticles with a size of ∼8 nm. • Composites exhibited excellent catalytic activity in the Suzuki reaction even after 10 cycles. - Abstract: Graphene sheets were decorated with palladium nanoparticles using a facile and efficient method in supercritical CO{sub 2}. The nanoparticles were formed on the graphene sheets by the simple hydrogen reduction of palladium(II) hexafluoroacetylacetonate precursor in supercritical CO{sub 2}. The product was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. Highly dispersed nanoparticles with various sizes and shapes adhered well to the graphene sheets. The composites showed high catalytic activities for the Suzuki reaction under aqueous and aerobic conditions within 5 min. The effects of the different Pd precursor loadings on the catalytic activities of the composites were also examined.

  3. Zeta potential of transfection complexes formed in serum-free medium can predict in vitro gene transfer efficiency of transfection reagent.

    Science.gov (United States)

    Son, K K; Tkach, D; Patel, D H

    2000-09-29

    We have tested the zeta potential (zeta, the surface charge density) of transfection complexes formed in serum-free medium as a rapid and reliable technique for screening transfection efficiency of a new reagent or formulation. The complexes of CAT plasmid DNA (1 microgram) and DC-chol/DOPE liposomes (3-20 nmol) were largely negatively charged (zeta=-15 to -21 mV), which became neutral or positive as 0.5 microgram or a higher amount of poly-L-lysine (PLL, MW 29300 or MW 204000) was added (-3.16+/-3.47 to +6.04+/-2.23 mV). However, the complexes of CAT plasmid DNA (1 microgram) and PLL MW 29300 (0.5 microgram or higher) were neutral or positively charged (-3.22+/-2.3 to +6.55+/-0.64 mV), which remained the same as 6.6 nmol of the liposomes was added. The complexes formed between two positively charged compounds, PLL MW 29300 (0.5 microgram) and the liposomes (3-20 nmol), were as closely positively charged as DNA/PLL or DNA/liposomes/PLL complexes (+3.31+/-0.41 to 7.16+/-1.0 mV). These results indicate that PLL determined the overall charge of the DNA/liposome/PLL ternary complexes. The complexes formed with histone (0.75 microgram or higher) were also positively charged, whose transfection activity was as high as PLL MW 29300. However, the complexes formed with protamine or PLL MW 2400 remained negatively charged. These observations are in good agreement with the transfection activity of the formulation containing each polycationic polymer. The presence of PLL MW 29300 did not change the hydrodynamic diameter of DNA/liposome/PLL complexes (d(H)=275-312 nm). The complexes made of different sizes of PLL (MW 2400 and 204000) also did not significantly change their size. This suggests that DNA condensation may not be critical. Therefore, zeta of the transfection complex can predict the transfection efficiency of a new formulation or reagent. PMID:11018646

  4. Catalytic Ozonation of Phenolic Wastewater: Identification and Toxicity of Intermediates

    OpenAIRE

    Mahdi Farzadkia; Yousef Dadban Shahamat; Simin Nasseri; Amir Hossein Mahvi; Mitra Gholami; Ali Shahryari

    2014-01-01

    A new strategy in catalytic ozonation removal method for degradation and detoxification of phenol from industrial wastewater was investigated. Magnetic carbon nanocomposite, as a novel catalyst, was synthesized and then used in the catalytic ozonation process (COP) and the effects of operational conditions such as initial pH, reaction time, and initial concentration of phenol on the degradation efficiency and the toxicity assay have been investigated. The results showed that the highest catal...

  5. First-principles investigation on the electronic efficiency and binding energy of the contacts formed by graphene and poly-aromatic hydrocarbon anchoring groups

    KAUST Repository

    Li, Yang

    2015-04-28

    © 2015 AIP Publishing LLC. The electronic efficiency and binding energy of contacts formed between graphene electrodes and poly-aromatic hydrocarbon (PAH) anchoring groups have been investigated by the non-equilibrium Green\\'s function formalism combined with density functional theory. Our calculations show that PAH molecules always bind in the interior and at the edge of graphene in the AB stacking manner, and that the binding energy increases following the increase of the number of carbon and hydrogen atoms constituting the PAH molecule. When we move to analyzing the electronic transport properties of molecular junctions with a six-carbon alkyne chain as the central molecule, the electronic efficiency of the graphene-PAH contacts is found to depend on the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the corresponding PAH anchoring group, rather than its size. To be specific, the smaller is the HOMO-LUMO gap of the PAH anchoring group, the higher is the electronic efficiency of the graphene-PAH contact. Although the HOMO-LUMO gap of a PAH molecule depends on its specific configuration, PAH molecules with similar atomic structures show a decreasing trend for their HOMO-LUMO gap as the number of fused benzene rings increases. Therefore, graphene-conjugated molecule-graphene junctions with high-binding and high-conducting graphene-PAH contacts can be realized by choosing appropriate PAH anchor groups with a large area and a small HOMO-LUMO gap.

  6. In situ synthesized gold nanoparticles in hydrogels for catalytic reduction of nitroaromatic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Xiao-Qiong; Wu, Xing-Wen; Huang, Qing [Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Shen, Jiang-Shan, E-mail: jsshen@iue.ac.cn [Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Ningbo Urban Environment Observation and Research Station, Chinese Academy of Sciences, Ningbo 315800 (China); Zhang, Hong-Wu, E-mail: hwzhang@iue.ac.cn [Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China)

    2015-03-15

    Graphical abstract: - Highlights: • In situ preparing Au nanoparticles by photoreduction in chitosan hydrogels was firstly achieved. • In situ photoreduction for creating Au nanoparticles is environmentally friendly and the operation procedure is very simple. • The as-prepared Au nanoparticles have good catalytic performance. • Affording an effective strategy for converting some high explosive compounds such as 2,4,6-tNT to nonexplosive. - Abstract: Developing hydrogel systems featured by catalytic active is of importance to construct highly effective platforms for removing environmental pollutants/hazardous substances or for bio-/chemosensing. Reported herein are our recent finding that Au nanoparticles could be in situ prepared in chitosan-Au{sup III} hydrogel system via photoreduction, and the as-prepared Au nanoparticles could be employed for the catalytic reduction of a series of nitroaromatic compounds by sodium borohydride (NaBH{sub 4}). Experimental conditions of synthesizing Au nanoparticles, including pH, concentration of Au{sup III}, and light irradiation time were systematically investigated. The as-prepared Au nanoparticles were characterized by UV–vis absorption spectroscopy, X-ray diffraction (XRD), transmission and field emission scanning electron microscopy (TEM and FESEM). This is the first example for in situ formed metal nanoparticles in chitosan hydrogel systems via photoreduction. The effectiveness of the as-prepared Au nanoparticles as nanocatalysts was evaluated by employing the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by NaBH{sub 4} as a model reaction. The catalytic reduction reaction was found to be very efficient and to follow a pseudo-first-order kinetics. The as-prepared Au nanoparticles demonstrated good reusability and stability. The reduction of a series of other nitroaromatic compounds including highly explosives 2,4,6-trinitrophenol (2,4,6-tNP) and 2,4,6-trinitrotoluene (2,4,6-tNT) was achieved by means

  7. Numerical Study of Passive Catalytic Recombiner for Hydrogen Mitigation

    Directory of Open Access Journals (Sweden)

    Pavan K Sharma

    2010-10-01

    Full Text Available A significant amount of hydrogen is expected to be released within the containment of a water cooled power reactor after a severe accident. To reduce the risk of deflagration/detonation various means for hydrogen control have been adopted all over the world. Passive catalytic recombiner with vertical flat catalytic plate is one of such hydrogen mitigating device. Passive catalytic recombiners are designed for the removal of hydrogen generated in order to limit the impact of possible hydrogen combustion. Inside a passive catalytic recombiner, numerous thin steel sheets coated with catalyst material are vertically arranged at the bottom opening of a sheet metal housing forming parallel flow channels for the surrounding gas atmosphere. Already below conventional flammability limits, hydrogen and oxygen react exothermally on the catalytic surfaces forming harmless steam. Detailed numerical simulations and experiments are required for an in-depth knowledge of such plate type catalytic recombiners. Specific finite volume based in-house CFD code has been developed to model and analyse the working of these recombiner. The code has been used to simulate the recombiner device used in the Gx-test series of Battelle-Model Containment (B-MC experiments. The present paper briefly describes the working principle of such passive catalytic recombiner and salient feature of the CFD model developed at Bhabha Atomic Research Centre (BARC. Finally results of the calculations and comparison with existing data are discussed.

  8. Revolutionary systems for catalytic combustion and diesel catalytic particulate traps.

    Energy Technology Data Exchange (ETDEWEB)

    Stuecker, John Nicholas; Witze, Peter O.; Ferrizz, Robert Matthew; Cesarano, Joseph, III; Miller, James Edward

    2004-12-01

    This report is a summary of an LDRD project completed for the development of materials and structures conducive to advancing the state of the art for catalyst supports and diesel particulate traps. An ancillary development for bio-medical bone scaffolding was also realized. Traditionally, a low-pressure drop catalyst support, such as a ceramic honeycomb monolith, is used for catalytic reactions that require high flow rates of gases at high-temperatures. A drawback to the traditional honeycomb monoliths under these operating conditions is poor mass transfer to the catalyst surface in the straight-through channels. ''Robocasting'' is a unique process developed at Sandia National Laboratories that can be used to manufacture ceramic monoliths with alternative 3-dimensional geometries, providing tortuous pathways to increase mass transfer while maintaining low-pressure drops. These alternative 3-dimensional geometries may also provide a foundation for the development of self-regenerating supports capable of trapping and combusting soot particles from a diesel engine exhaust stream. This report describes the structures developed and characterizes the improved catalytic performance that can result. The results show that, relative to honeycomb monolith supports, considerable improvement in mass transfer efficiency is observed for robocast samples synthesized using an FCC-like geometry of alternating rods. Also, there is clearly a trade-off between enhanced mass transfer and increased pressure drop, which can be optimized depending on the particular demands of a given application. Practical applications include the combustion of natural gas for power generation, production of syngas, and hydrogen reforming reactions. The robocast lattice structures also show practicality for diesel particulate trapping. Preliminary results for trapping efficiency are reported as well as the development of electrically resistive lattices that can regenerate the structure

  9. Development of Catalytic Cooking Plates

    Energy Technology Data Exchange (ETDEWEB)

    Hjelm, Anna-Karin; Silversand, Fredrik [CATATOR AB, Lund (Sweden); Tena, Emmanuel; Berger, Marc [Gaz de France (France)

    2004-04-01

    Gas catalytic combustion for gas stoves or cooking plates (closed catalytic burner system with ceramic plates) is a very promising technique in terms of ease of cleaning, power modulation and emissions. Previous investigations show that wire mesh catalysts, prepared and supplied by Catator AB (CAT), seem to be very well suited for such applications. Beside significantly reducing the NOx-emissions, these catalysts offer important advantages such as good design flexibility, low pressure drop and high heat transfer capacity, where the latter leads to a quick thermal response. Prior to this project, Gaz de France (GdF) made a series of measurements with CAT's wire mesh catalysts in their gas cooking plates and compared the measured performance with similar results obtained with theirs cordierite monolith catalysts. Compared to the monolith catalyst, the wire mesh catalyst was found to enable very promising results with respect to both emission levels (<10 mg NO{sub x} /kWh, <5 mg CO/kWh) and life-time (>8000 h vs. 700 h at 200 kW/m{sup 2}). It was however established that the radiation and hence, the thermal efficiency of the cooking plate, was significantly less than is usually measured in combination with the monolith (15 % vs. 32 %). It was believed that the latter could be improved by developing new burner designs based on CAT's wire mesh concept. As a consequence, a collaboration project between GdF, CAT and the Swedish Gas Technology AB was created. This study reports on the design, the construction and the evaluation of new catalytic burners, based on CAT's wire mesh catalysts, used for the combustion of natural gas in gas cooking stoves. The evaluation of the burners was performed with respect to key factors such as thermal efficiency, emission quality and pressure drop, etc, by the use of theoretical simulations and experimental tests. Impacts of parameters such as the the wire mesh number, the wire mesh structure (planar or folded), the

  10. Orion EFT-1 Catalytic Tile Experiment Overview and Flight Measurements

    Science.gov (United States)

    Salazar, Giovanni; Amar, Adam; Hyatt, Andrew; Rezin, Marc D.

    2016-01-01

    This paper describes the design and results of a surface catalysis flight experiment flown on the Orion Multipurpose Crew Vehicle during Exploration Flight Test 1 (EFT1). Similar to previous Space Shuttle catalytic tile experiments, the present test consisted of a highly catalytic coating applied to an instrumented TPS tile. However, the present catalytic tile experiment contained significantly more instrumentation in order to better resolve the heating overshoot caused by the change in surface catalytic efficiency at the interface between two distinct materials. In addition to collecting data with unprecedented spatial resolution of the "overshoot" phenomenon, the experiment was also designed to prove if such a catalytic overshoot would be seen in turbulent flow in high enthalpy regimes. A detailed discussion of the results obtained during EFT1 is presented, as well as the challenges associated with data interpretation of this experiment. Results of material testing carried out in support of this flight experiment are also shown. Finally, an inverse heat conduction technique is employed to reconstruct the flight environments at locations upstream and along the catalytic coating. The data and analysis presented in this work will greatly contribute to our understanding of the catalytic "overshoot" phenomenon, and have a significant impact on the design of future spacecraft.

  11. Novel Catalytic Membrane Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Stuart Nemser, PhD

    2010-10-01

    There are many industrial catalytic organic reversible reactions with amines or alcohols that have water as one of the products. Many of these reactions are homogeneously catalyzed. In all cases removal of water facilitates the reaction and produces more of the desired chemical product. By shifting the reaction to right we produce more chemical product with little or no additional capital investment. Many of these reactions can also relate to bioprocesses. Given the large number of water-organic compound separations achievable and the ability of the Compact Membrane Systems, Inc. (CMS) perfluoro membranes to withstand these harsh operating conditions, this is an ideal demonstration system for the water-of-reaction removal using a membrane reactor. Enhanced reaction synthesis is consistent with the DOE objective to lower the energy intensity of U.S. industry 25% by 2017 in accord with the Energy Policy Act of 2005 and to improve the United States manufacturing competitiveness. The objective of this program is to develop the platform technology for enhancing homogeneous catalytic chemical syntheses.

  12. Catalytic pleat filter bags for combined particulate separation and nitrogen oxides removal from flue gas streams

    International Nuclear Information System (INIS)

    The development of a high temperature catalytically active pleated filter bag with hybrid filter equipment for the combined removal of particles and nitrogen oxides from flue gas streams is presented. A special catalyst load in stainless steel mesh cartridge with a high temperature pleated filter bag followed by optimized catalytic activation was developed to reach the required nitrogen oxides levels and to maintain the higher collection efficiencies. The catalytic properties of the developed high temperature filter bags with hybrid filter equipment were studied and demonstrated in a pilot scale test rig and a demonstration plant using commercial scale of high temperature catalytic pleated filter bags. The performance of the catalytic pleated filter bags were tested under different operating conditions, such as filtration velocity and operating temperature. Moreover, the cleaning efficiency and residual pressure drop of the catalyst loaded cartridges in pleated filter bags were tested. As result of theses studies, the optimum operating conditions for the catalytic pleated filter bags are determined. (author)

  13. Reaction Current Phenomenon in Bifunctional Catalytic Metal-Semiconductor Nanostructures

    Science.gov (United States)

    Hashemian, Mohammad Amin

    Energy transfer processes accompany every elementary step of catalytic chemical processes on material surface including molecular adsorption and dissociation on atoms, interactions between intermediates, and desorption of reaction products from the catalyst surface. Therefore, detailed understanding of these processes on the molecular level is of great fundamental and practical interest in energy-related applications of nanomaterials. Two main mechanisms of energy transfer from adsorbed particles to a surface are known: (i) adiabatic via excitation of quantized lattice vibrations (phonons) and (ii) non-adiabatic via electronic excitations (electron/hole pairs). Electronic excitations play a key role in nanocatalysis, and it was recently shown that they can be efficiently detected and studied using Schottky-type catalytic nanostructures in the form of measureable electrical currents (chemicurrents) in an external electrical circuit. These nanostructures typically contain an electrically continuous nanocathode layers made of a catalytic metal deposited on a semiconductor substrate. The goal of this research is to study the direct observations of hot electron currents (chemicurrents) in catalytic Schottky structures, using a continuous mesh-like Pt nanofilm grown onto a mesoporous TiO2 substrate. Such devices showed qualitatively different and more diverse signal properties, compared to the earlier devices using smooth substrates, which could only be explained on the basis of bifunctionality. In particular, it was necessary to suggest that different stages of the reaction are occurring on both phases of the catalytic structure. Analysis of the signal behavior also led to discovery of a formerly unknown (very slow) mode of the oxyhydrogen reaction on the Pt/TiO2(por) system occurring at room temperature. This slow mode was producing surprisingly large stationary chemicurrents in the range 10--50 microA/cm2. Results of the chemicurrent measurements for the bifunctional

  14. Efficient expression of the anti-AahI' scorpion toxin nanobody under a new functional form in a Pichia pastoris system.

    Science.gov (United States)

    Ezzine, Aymen; M'hirsi El Adab, Sonia; Bouhaouala-Zahar, Balkiss; Hmila, Issam; Baciou, Laura; Marzouki, Mohamed Najib

    2012-01-01

    Most large-scale microbial production of recombinant proteins are based on Escherichia coli, yeasts, or filamentous fungi systems. Using eukaryotic hosts, antibody fragments are generally expressed by targeting to the secretory pathway. This enables not only efficient disulfide bond formation but also secretion of soluble and correctly folded product. For this goal, a recombinant vector was constructed to produce a single-domain antibody (NbAahI'22) directed against AahI' scorpion toxin using the methylotrophic yeast Pichia pastoris. The corresponding complementary DNA was cloned under control of the alcohol oxidase promoter in frame with the Saccharomyces α-factor secretion signal and then transferred to P. pastoris cell strain X-33. Using Western blot, we detected the expression of the recombinant NbAahI'22 exclusively in the culture medium. Targeting to the histidine label, the secreted nanobody was easily purified on nickel-nitrilotriacetic acid resin and then tested in enzyme-linked immunosorbent assay. Interestingly, the production level of the NbAahI'22 in its new glycosylated form reached more than sixfold that obtained in E. coli. These findings give more evidence for the utilization of P. pastoris as a heterologous expression system. PMID:22332740

  15. The effect of Na2S2O8 oxidant on improving the efficiency of photo-catalytic process of nano-TiO2 immobilized on concrete in DB71 removal

    Directory of Open Access Journals (Sweden)

    Masoumeh Panbehkar Bishe

    2014-07-01

    Conclusion: Oxidant addition increased the dye removal efficiency and decreased total time for complete decolorization indicating the positive effect of oxidant on photocatalytic process in dye removal.

  16. HYDROGEN TRANSFER IN CATALYTIC CRACKING

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Hydrogen transfer is an important secondary reaction of catalytic cracking reactions, which affects product yield distribution and product quality. It is an exothermic reaction with low activation energy around 43.3 kJ/mol. Catalyst properties and operation parameters in catalytic cracking greatly influence the hydrogen transfer reaction. Satisfactory results are expected through careful selection of proper catalysts and operation conditions.

  17. Chemistry - Toward efficient hydrogen production at surfaces

    DEFF Research Database (Denmark)

    Nørskov, Jens Kehlet; Christensen, Claus H.

    2006-01-01

    Calculations are providing a molecular picture of hydrogen production on catalytic surfaces and within enzymes, knowledge that may guide the design of new, more efficient catalysts for the hydrogen economy.......Calculations are providing a molecular picture of hydrogen production on catalytic surfaces and within enzymes, knowledge that may guide the design of new, more efficient catalysts for the hydrogen economy....

  18. Halogen Chemistry on Catalytic Surfaces.

    Science.gov (United States)

    Moser, Maximilian; Pérez-Ramírez, Javier

    2016-01-01

    Halogens are key building blocks for the manufacture of high-value products such as chemicals, plastics, and pharmaceuticals. The catalytic oxidation of HCl and HBr is an attractive route to recover chlorine and bromine in order to ensure the sustainability of the production processes. Very few materials withstand the high corrosiveness and the strong exothermicity of the reactions and among them RuO2 and CeO2-based catalysts have been successfully applied in HCl oxidation. The search for efficient systems for HBr oxidation was initiated by extrapolating the results of HCl oxidation based on the chemical similarity of these reactions. Interestingly, despite its inactivity in HCl oxidation, TiO2 was found to be an outstanding HBr oxidation catalyst, which highlighted that the latter reaction is more complex than previously assumed. Herein, we discuss the results of recent comparative studies of HCl and HBr oxidation on both rutile-type (RuO2, IrO2, and TiO2) and ceria-based catalysts using a combination of advanced experimental and theoretical methods to provide deeper molecular-level understanding of the reactions. This knowledge aids the design of the next-generation catalysts for halogen recycling. PMID:27131113

  19. Bifunctional catalytic electrode

    Science.gov (United States)

    Cisar, Alan (Inventor); Murphy, Oliver J. (Inventor); Clarke, Eric (Inventor)

    2005-01-01

    The present invention relates to an oxygen electrode for a unitized regenerative hydrogen-oxygen fuel cell and the unitized regenerative fuel cell having the oxygen electrode. The oxygen electrode contains components electrocatalytically active for the evolution of oxygen from water and the reduction of oxygen to water, and has a structure that supports the flow of both water and gases between the catalytically active surface and a flow field or electrode chamber for bulk flow of the fluids. The electrode has an electrocatalyst layer and a diffusion backing layer interspersed with hydrophilic and hydrophobic regions. The diffusion backing layer consists of a metal core having gas diffusion structures bonded to the metal core.

  20. Chaperones are necessary for the expression of catalytically active potato apyrases in prokaryotic cells.

    Science.gov (United States)

    Porowińska, Dorota; Czarnecka, Joanna; Komoszyński, Michał

    2014-07-01

    NTPDases (nucleoside triphosphate diphosphohydrolases) (also called in plants apyrases) hydrolyze nucleoside 5'-tri- and/or diphosphate bonds producing nucleosides di or monophosphate and inorganic phosphate. For years, studies have been carried out to use both plant and animal enzymes for medicine. Therefore, there is a need to develop an efficient method for the quick production of large amounts of homogeneous proteins with high catalytic activity. Expression of proteins in prokaryotic cells is the most common way for the protein production. The aim of our study was to develop a method of expression of potato apyrase (StAPY4, 5, and 6) genes in bacterial cells under conditions that allowed the production of catalytically active form of these enzymes. Apyrase 4 and 6 were overexpressed in BL21-CodonPlus (DE3) bacteria strain but they were accumulated in inclusion bodies, regardless of the culture conditions and induction method. Co-expression of potato apyrases with molecular chaperones allowed the expression of catalytically active apyrase 5. However, its high nucleotidase activity could be toxic for bacteria and is therefore synthesized in small amounts in cells. Our studies show that each protein requires other conditions for maturation and even small differences in amino acid sequence can essentially affect protein folding regardless of presence of chaperones.

  1. Preparation and photo-catalytic activities of FeOOH/ZnO/MMT composite

    Science.gov (United States)

    Zhou, Yao; Liu, Fusheng; Yu, Shitao

    2015-11-01

    Montmorillonite (MMT) was used as the carrier for synthesis of FeOOH and FeOOH/ZnO nano-material. FeOOH and FeOOH/ZnO were synthesized by the aqueous solutions of Fe(NO3)3-HNO3 and Zn(NO3)2-NaOH/Fe(NO3)3-HNO3 with the carrier of montmorillonite respectively. Transmission electron-microscopy (TEM) and X-ray diffraction (XRD) were used to study the morphology form and structure of the nano-materials. TEM was also used to demonstrate that FeOOH/ZnO can be formed with the appropriate interface. According to UV-vis absorption spectra, FeOOH/ZnO has a better response to visible light than FeOOH and ZnO, which indicates there is some coupling effect between FeOOH and ZnO. Pentachlorophenol (PCP) was used as a representative organic pollutant to evaluate the photo-catalytic efficiency of the FeOOH/ZnO and FeOOH catalysts in visible light (λ > 400 nm). The photo-catalytic efficiency of FeOOH/ZnO/MMT is better than FeOOH/MMT. According to FTIR, changes of pH and TOC, the degradation mechanism was also discussed. PCP was degraded to aromatic ketone and chloro-hydrocarbon compounds and then to H2O, CO2 and HCl.

  2. Probing catalytic rate enhancement during intramembrane proteolysis.

    Science.gov (United States)

    Arutyunova, Elena; Smithers, Cameron C; Corradi, Valentina; Espiritu, Adam C; Young, Howard S; Tieleman, D Peter; Lemieux, M Joanne

    2016-09-01

    Rhomboids are ubiquitous intramembrane serine proteases involved in various signaling pathways. While the high-resolution structures of the Escherichia coli rhomboid GlpG with various inhibitors revealed an active site comprised of a serine-histidine dyad and an extensive oxyanion hole, the molecular details of rhomboid catalysis were unclear because substrates are unknown for most of the family members. Here we used the only known physiological pair of AarA rhomboid with its psTatA substrate to decipher the contribution of catalytically important residues to the reaction rate enhancement. An MD-refined homology model of AarA was used to identify residues important for catalysis. We demonstrated that the AarA active site geometry is strict and intolerant to alterations. We probed the roles of H83 and N87 oxyanion hole residues and determined that substitution of H83 either abolished AarA activity or reduced the transition state stabilization energy (ΔΔG‡) by 3.1 kcal/mol; substitution of N87 decreased ΔΔG‡ by 1.6-3.9 kcal/mol. Substitution M154, a residue conserved in most rhomboids that stabilizes the catalytic general base, to tyrosine, provided insight into the mechanism of nucleophile generation for the catalytic dyad. This study provides a quantitative evaluation of the role of several residues important for hydrolytic efficiency and oxyanion stabilization during intramembrane proteolysis. PMID:27071148

  3. Catalytic applications of bio-inspired nanomaterials

    Science.gov (United States)

    Pacardo, Dennis Kien Balaong

    The biomimetic synthesis of Pd nanoparticles was presented using the Pd4 peptide, TSNAVHPTLRHL, isolated from combinatorial phage display library. Using this approach, nearly monodisperse and spherical Pd nanoparticles were generated with an average diameter of 1.9 +/- 0.4 nm. The peptide-based nanocatalyst were employed in the Stille coupling reaction under energy-efficient and environmentally friendly reaction conditions of aqueous solvent, room temperature and very low catalyst loading. To this end, the Pd nanocatalyst generated high turnover frequency (TOF) value and quantitative yields using ≥ 0.005 mol% Pd as well as catalytic activities with different aryl halides containing electron-withdrawing and electron-donating groups. The Pd4-capped Pd nanoparticles followed the atom-leaching mechanism and were found to be selective with respect to substrate identity. On the other hand, the naturally-occurring R5 peptide (SSKKSGSYSGSKGSKRRIL) was employed in the synthesis of biotemplated Pd nanomaterials which showed morphological changes as a function of Pd:peptide ratio. TOF analysis for hydrogenation of olefinic alcohols showed similar catalytic activity regardless of nanomorphology. Determination of catalytic properties of these bio-inspired nanomaterials are important as they serve as model system for alternative green catalyst with applications in industrially important transformations.

  4. 3-Nitropropionic Acid is a Suicide Inhibitor of MitochondrialRespiration that, Upon Oxidation by Complex II, Forms a Covalent AdductWith a Catalytic Base Arginine in the Active Site of the Enzyme

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Li-shar; Sun, Gang; Cobessi, David; Wang, Andy C.; Shen,John T.; Tung, Eric Y.; Anderson, Vernon E.; Berry, Edward A.

    2005-12-01

    We report three new structures of mitochondrial respiratory Complex II (succinate ubiquinone oxidoreductase, E.C. 1.3.5.1) at up to 2.1 {angstrom} resolution, with various inhibitors. The structures define the conformation of the bound inhibitors and suggest the residues involved in substrate binding and catalysis at the dicarboxylate site. In particular they support the role of Arg297 as a general base catalyst accepting a proton in the dehydrogenation of succinate. The dicarboxylate ligand in oxaloacetate-containing crystals appears to be the same as that reported for Shewanella flavocytochrome c treated with fumarate. The plant and fungal toxin 3-nitropropionic acid, an irreversible inactivator of succinate dehydrogenase, forms a covalent adduct with the side chain of Arg297. The modification eliminates a trypsin cleavage site in the flavoprotein, and tandem mass spectroscopic analysis of the new fragment shows the mass of Arg 297 to be increased by 83 Da and to have potential of losing 44 Da, consistent with decarboxylation, during fragmentation.

  5. 3-Nitropropionic Acid is a Suicide Inhibitor of Mitochondrial Respiration that, Upon Oxidation by Complex II, Forms a Covalent Adduct With a Catalytic Base Arginine in the Active Site of the Enzyme

    International Nuclear Information System (INIS)

    We report three new structures of mitochondrial respiratory Complex II (succinate ubiquinone oxidoreductase, E.C. 1.3.5.1) at up to 2.1 (angstrom) resolution, with various inhibitors. The structures define the conformation of the bound inhibitors and suggest the residues involved in substrate binding and catalysis at the dicarboxylate site. In particular they support the role of Arg297 as a general base catalyst accepting a proton in the dehydrogenation of succinate. The dicarboxylate ligand in oxaloacetate-containing crystals appears to be the same as that reported for Shewanella flavocytochrome c treated with fumarate. The plant and fungal toxin 3-nitropropionic acid, an irreversible inactivator of succinate dehydrogenase, forms a covalent adduct with the side chain of Arg297. The modification eliminates a trypsin cleavage site in the flavoprotein, and tandem mass spectroscopic analysis of the new fragment shows the mass of Arg 297 to be increased by 83 Da and to have potential of losing 44 Da, consistent with decarboxylation, during fragmentation

  6. Catalytic Chemistry on Oxide Nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Asthagiri, Aravind; Dixon, David A.; Dohnalek, Zdenek; Kay, Bruce D.; Rodriquez, Jose A.; Rousseau, Roger J.; Stacchiola, Dario; Weaver, Jason F.

    2016-05-29

    Metal oxides represent one of the most important and widely employed materials in catalysis. Extreme variability of their chemistry provides a unique opportunity to tune their properties and to utilize them for the design of highly active and selective catalysts. For bulk oxides, this can be achieved by varying their stoichiometry, phase, exposed surface facets, defect, dopant densities and numerous other ways. Further, distinct properties from those of bulk oxides can be attained by restricting the oxide dimensionality and preparing them in the form of ultrathin films and nanoclusters as discussed throughout this book. In this chapter we focus on demonstrating such unique catalytic properties brought by the oxide nanoscaling. In the highlighted studies planar models are carefully designed to achieve minimal dispersion of structural motifs and to attain detailed mechanistic understanding of targeted chemical transformations. Detailed level of morphological and structural characterization necessary to achieve this goal is accomplished by employing both high-resolution imaging via scanning probe methods and ensemble-averaged surface sensitive spectroscopic methods. Three prototypical examples illustrating different properties of nanoscaled oxides in different classes of reactions are selected.

  7. Chemically-Modified Cellulose Paper as a Microstructured Catalytic Reactor

    Directory of Open Access Journals (Sweden)

    Hirotaka Koga

    2015-01-01

    Full Text Available We discuss the successful use of chemically-modified cellulose paper as a microstructured catalytic reactor for the production of useful chemicals. The chemical modification of cellulose paper was achieved using a silane-coupling technique. Amine-modified paper was directly used as a base catalyst for the Knoevenagel condensation reaction. Methacrylate-modified paper was used for the immobilization of lipase and then in nonaqueous transesterification processes. These catalytic paper materials offer high reaction efficiencies and have excellent practical properties. We suggest that the paper-specific interconnected microstructure with pulp fiber networks provides fast mixing of the reactants and efficient transport of the reactants to the catalytically-active sites. This concept is expected to be a promising route to green and sustainable chemistry.

  8. Studies on Nitrogen Oxides Removal Using Plasma Assisted Catalytic Reactor

    Institute of Scientific and Technical Information of China (English)

    V. Ravi; Young Sun Mok; B. S. Rajanikanth; Ho-Chul Kang

    2003-01-01

    An electric discharge plasma reactor combined with a catalytic reactor was studied for removing nitrogen oxides. To understand the combined process thoroughly, discharge plasma and catalytic process were separately studied first, and then the two processes were combined for the study. The plasma reactor was able to oxidize NO to NO2 well although the oxidation rate decreased with temperature. The plasma reactor alone did not reduce the NOx (NO+NO2)level effectively, but the increase in the ratio of NO2 to NO as a result of plasma discharge led to the enhancement of NOx removal efficiency even at lower temperatures over the catalyst surface (V2O5-WOa/TiO2). At a gas temperature of 100℃, the NOx removal efficiency obtained using the combined plasma catalytic process was 88% for an energy input of 36 eV/molecule or 30 J/1.

  9. Transport in a Microfluidic Catalytic Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Park, H G; Chung, J; Grigoropoulos, C P; Greif, R; Havstad, M; Morse, J D

    2003-04-30

    A study of the heat and mass transfer, flow, and thermodynamics of the reacting flow in a catalytic microreactor is presented. Methanol reforming is utilized in the fuel processing system driving a micro-scale proton exchange membrane fuel cell. Understanding the flow and thermal transport phenomena as well as the reaction mechanisms is essential for improving the efficiency of the reforming process as well as the quality of the processed fuel. Numerical studies have been carried out to characterize the transport in a silicon microfabricated reactor system. On the basis of these results, optimized conditions for fuel processing are determined.

  10. Heterogeneous Photooxidation of Phenol by Catalytic Membranes

    Institute of Scientific and Technical Information of China (English)

    Enrica Fontananova; Enrico Drioli; Laura Donato; Marcella Bonchio; Mauro Carraro; Gianfranco Scorrano

    2006-01-01

    In this work the heterogenization in polymeric membranes of decatungstate, a photocatalyst for oxidation reactions,was reported. Solid state characterization techniques confirmed that the catalyst structure was preserved within the polymeric membranes. The catalytic membranes were successfully applied in the aerobic photo-oxidation of phenol, one of the main organic pollutants in wastewater, providing stable and recyclable photocatalytic systems. The dependence of the phenol degradation rate by the catalyst loading and transmembrane pressure was shown. By comparison with homogeneous reaction,the catalyst heterogenized in membrane appears to be more efficient concerning the rate of phenol photodegradation and mineralization.

  11. Molecular Self-Assembly Strategy for Generating Catalytic Hybrid Polypeptides

    Science.gov (United States)

    Ikezoe, Yasuhiro; Pike, Douglas H.; Nanda, Vikas; Matsui, Hiroshi

    2016-01-01

    Recently, catalytic peptides were introduced that mimicked protease activities and showed promising selectivity of products even in organic solvents where protease cannot perform well. However, their catalytic efficiency was extremely low compared to natural enzyme counterparts presumably due to the lack of stable tertiary fold. We hypothesized that assembling these peptides along with simple hydrophobic pockets, mimicking enzyme active sites, could enhance the catalytic activity. Here we fused the sequence of catalytic peptide CP4, capable of protease and esterase-like activities, into a short amyloidogenic peptide fragment of Aβ. When the fused CP4-Aβ construct assembled into antiparallel β-sheets and amyloid fibrils, a 4.0-fold increase in the hydrolysis rate of p-nitrophenyl acetate (p-NPA) compared to neat CP4 peptide was observed. The enhanced catalytic activity of CP4-Aβ assembly could be explained both by pre-organization of a catalytically competent Ser-His-acid triad and hydrophobic stabilization of a bound substrate between the triad and p-NPA, indicating that a design strategy for self-assembled peptides is important to accomplish the desired functionality. PMID:27116246

  12. Catalytic Synthesis of Oxygenates: Mechanisms, Catalysts and Controlling Characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Klier, Kamil; Herman, Richard G

    2005-11-30

    This research focused on catalytic synthesis of unsymmetrical ethers as a part of a larger program involving oxygenated products in general, including alcohols, ethers, esters, carboxylic acids and their derivatives that link together environmentally compliant fuels, monomers, and high-value chemicals. The catalysts studied here were solid acids possessing strong Brnsted acid functionalities. The design of these catalysts involved anchoring the acid groups onto inorganic oxides, e.g. surface-grafted acid groups on zirconia, and a new class of mesoporous solid acids, i.e. propylsulfonic acid-derivatized SBA-15. The former catalysts consisted of a high surface concentration of sulfate groups on stable zirconia catalysts. The latter catalyst consists of high surface area, large pore propylsulfonic acid-derivatized silicas, specifically SBA-15. In both cases, the catalyst design and synthesis yielded high concentrations of acid sites in close proximity to one another. These materials have been well-characterization in terms of physical and chemical properties, as well as in regard to surface and bulk characteristics. Both types of catalysts were shown to exhibit high catalytic performance with respect to both activity and selectivity for the bifunctional coupling of alcohols to form ethers, which proceeds via an efficient SN2 reaction mechanism on the proximal acid sites. This commonality of the dual-site SN2 reaction mechanism over acid catalysts provides for maximum reaction rates and control of selectivity by reaction conditions, i.e. pressure, temperature, and reactant concentrations. This research provides the scientific groundwork for synthesis of ethers for energy applications. The synthesized environmentally acceptable ethers, in part derived from natural gas via alcohol intermediates, exhibit high cetane properties, e.g. methylisobutylether with cetane No. of 53 and dimethylether with cetane No. of 55-60, or high octane properties, e.g. diisopropylether with

  13. A QM/MM study of the catalytic mechanism of nicotinamidase.

    Science.gov (United States)

    Sheng, Xiang; Liu, Yongjun

    2014-02-28

    Nicotinamidase (Pnc1) is a member of Zn-dependent amidohydrolases that hydrolyzes nicotinamide (NAM) to nicotinic acid (NA), which is a key step in the salvage pathway of NAD(+) biosynthesis. In this paper, the catalytic mechanism of Pnc1 has been investigated by using a combined quantum-mechanical/molecular-mechanical (QM/MM) approach based on the recently obtained crystal structure of Pnc1. The reaction pathway, the detail of each elementary step, the energetics of the whole catalytic cycle, and the roles of key residues and Zn-binding site are illuminated. Our calculation results indicate that the catalytic water molecule comes from the bulk solvent, which is then deprotonated by residue D8. D8 functions as a proton transfer station between C167 and NAM, while the activated C167 serves as the nucleophile. The residue K122 only plays a role in stabilizing intermediates and transition states. The oxyanion hole formed by the amide backbone nitrogen atoms of A163 and C167 has the function to stabilize the hydroxyl anion of nicotinamide. The Zn-binding site rather than a single Zn(2+) ion acts as a Lewis acid to influence the reaction. Two elementary steps, the activation of C167 in the deamination process and the decomposition of catalytic water in the hydrolysis process, correspond to the large energy barriers of 25.7 and 28.1 kcal mol(-1), respectively, meaning that both of them contribute a lot to the overall reaction barrier. Our results may provide useful information for the design of novel and efficient Pnc1 inhibitors and related biocatalytic applications. PMID:24413890

  14. Teaching Form as Form

    DEFF Research Database (Denmark)

    Keiding, Tina Bering

    2012-01-01

    means that form serves both as the connective value and as the concept for reflection. In other words, form is observed as form, not anything else. The didactical challenge of teaching form as form is accentuated by students’ everyday-based pre-orientation towards function at the expense of form...... reveal highly-structured courses, which alternates systematically between steering and free experimental activities. Consistent with a strong focus on content and the student’s interaction with content, the contributions hardly address the role of the teacher or the interplay between teachers...... and students. This is not to say that teachers do not engage in teaching. They clearly do and obviously play a major role in the progression in course structure and reflection on the student’s learning. My point is that, by neglecting the role of the teacher and the interplay between the teacher and students...

  15. Catalytic Membrane Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Boyle, T.J.; Brinker, C.J.; Gardner, T.J.; Hughes, R.C.; Sault, A.G.

    1998-12-01

    The proposed "catalytic membrane sensor" (CMS) was developed to generate a device which would selectively identify a specific reagent in a complex mixture of gases. This was to be accomplished by modifying an existing Hz sensor with a series of thin films. Through selectively sieving the desired component from a complex mixture and identifying it by decomposing it into Hz (and other by-products), a Hz sensor could then be used to detect the presence of the select component. The proposed "sandwich-type" modifications involved the deposition of a catalyst layered between two size selective sol-gel layers on a Pd/Ni resistive Hz sensor. The role of the catalyst was to convert organic materials to Hz and organic by-products. The role of the membraneo was to impart both chemical specificity by molecukir sieving of the analyte and converted product streams, as well as controlling access to the underlying Pd/Ni sensor. Ultimately, an array of these CMS elements encompassing different catalysts and membranes were to be developed which would enable improved selectivity and specificity from a compiex mixture of organic gases via pattern recognition methodologies. We have successfully generated a CMS device by a series of spin-coat deposited methods; however, it was determined that the high temperature required to activate the catalyst, destroys the sensor.

  16. TESTING THE SEMI-STRONG FORM OF THE EFFICIENT MARKET HYPOTHESIS ON PUBLIC OFFERS FOR ACQUISITION/TAKEOVER IN THE PHARMACEUTICAL AND THE ALUMINIUM SECTORS OF THE ROMANIAN CAPITAL MARKET

    OpenAIRE

    Dragos Ioan Minjina; Oana Resceanu

    2008-01-01

    The efficiency of the capital market is one of the most studied hypotheses, having an important impact, both in financial modelling and real economy. The research paper is focused on the announcements for acquisitions and takeover public offers for companies acting in the pharmaceutical and the aluminium sectors listed on the Romanian capital market. After testing the semi-strong form of the efficient market hypothesis in Romania, using the event studies technique for these announcements, the...

  17. Biopolymer coated gold nanocrystals prepared using the green chemistry approach and their shape-dependent catalytic and surface-enhanced Raman scattering properties.

    Science.gov (United States)

    Chou, Chih-Wei; Hsieh, Hui-Hsuan; Hseu, You-Cheng; Chen, Ko-Shao; Wang, Gou-Jen; Chang, Hsien-Chang; Pan, Yong-Li; Wei, Yi-Syuan; Chang, Ko Hsin; Harn, Yeu-Wei

    2013-07-21

    This study deals with the preparation of multi-shaped nanoscale gold crystals under synthetically simple, green, and efficient conditions using a seed-mediated growth approach in the presence of hyaluronic acid (HA). These highly biocompatible multi-shaped gold nanocrystals were examined to evaluate their catalytic and surface enhanced Raman scattering (SERS) properties. The results show that the size and shape of the nanocrystals are mainly correlated to the amount of seed, seed size, HA concentration, and reaction temperature. Gold seeds accelerate the reduction of the gold precursor to form gold nanocrystals using HA. The HA serves as a reducing agent and a growth template for the reduction of Au(III) and nanocrystal stabilization. The multi-shaped gold nanocrystals showed superior catalytic properties and higher SERS performance. The simple, green approach efficiently controls the nanocrystals and creates many opportunities for future applications. PMID:23728083

  18. In situ formed Bi/BiOBrxI1-x heterojunction of hierarchical microspheres for efficient visible-light photocatalytic activity.

    Science.gov (United States)

    Zheng, Chunrui; Cao, Chuanbao; Ali, Zulfiqar

    2015-05-28

    Bi nanoparticles deposited in situ in BiOBrxI1-x hierarchical microspheres (Bi/BiOBrxI1-x heterojunction) were synthesized by a facile one-step solvothermal method. The as-prepared samples were characterized via XRD, SEM, TEM, XPS, UV-vis absorption spectroscopy and N2 adsorption-desorption. The hierarchical microspheres were composed of numerous nanosheets aggregated together compactly to form a spherical geometry. Results indicated that Bi nanoparticles were generated on the surface of BiOBrxI1-x microspheres via the in situ reduction of Bi(3+) by ethylene glycol. BiOBrxI1-x microspheres with deposited Bi nanoparticles were employed for the degradation of RhB under visible-light irradiation and the samples exhibited exceptionally enhanced photocatalytic activity. This immense enhancement in photocatalytic activity was attributed to the contribution of Bi nanoparticles to the efficient separation of electron-hole pairs and prolongation of the lifetime of charge carriers. The behavior of Bi nanoparticles as a cocatalyst for enhancing photocatalytic activity is similar to that of noble metals in photocatalysis. The as-prepared Bi/BiOBr0.266I0.734 sample exhibited highest photocatalytic activity, which exceeded those of other types of visible-light photocatalysts such as N-TiO2, Eu(3+)-BiOI, BiOBr, BiOBr0.2I0.8/graphene and even Ag/AgBr/BiOBr. The Bi/BiOBr0.266I0.734 sample displayed high photochemical stability under repeated visible-light irradiation, which is especially important for its practical application. The active species produced from Bi/BiOBrxI1-x under visible light were hydroxyl radicals. Bi/BiOBrxI1-x could generate more hydroxyl radicals due to the Bi nanoparticles, contributing to the enhance oxidation ability. This study demonstrated the high feasibility of utilizing low-cost Bi nanoparticles as a substitute for noble metals to enhance visible-light photocatalysis.

  19. Immigration process in catalytic medium

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The longtime behavior of the immigration process associated with a catalytic super-Brownian motion is studied. A large number law is proved in dimension d≤3 and a central limit theorem is proved for dimension d=3.

  20. Immigration process in catalytic medium

    Institute of Scientific and Technical Information of China (English)

    洪文明; 王梓坤

    2000-01-01

    The longtime behavior of the immigration process associated with a catalytic super-Brown-ian motion is studied. A large number law is proved in dimension d≤3 and a central limit theorem is proved for dimension d = 3.

  1. Development of a para-orthohydrogen catalytic converter for a solid hydrogen cooler

    Science.gov (United States)

    Nast, T. C.; Hsu, I. C.

    1984-01-01

    Design features of a tested catalytic converter for altering vented cryogenic parahydrogen used as a coolant on spacecraft into a para-ortho equilibrium for channeling to other cooling functions are described. The hydrogen is expected to be stored in either liquid or solid form. A high surface area Ni-on-Si catalyst was selected for tests at an operating pressure of 2 torr at a ratio of 1000 gr catalyst for a gr/sec hydrogen flow. Cylindrical and radial flow geometries were tried and measurements centered on the converter efficiencies at different operating temperatures when the converter was placed in the vent line of the H2 cooler. Efficiencies ranging from 10-100 percent were obtained for varying flow rates. Further testing is necessary to characterize the converter performance under a wider range of operating temperatures and environments.

  2. Catalytic enantioselective addition of organoboron reagents to fluoroketones controlled by electrostatic interactions

    Science.gov (United States)

    Lee, Kyunga; Silverio, Daniel L.; Torker, Sebastian; Robbins, Daniel W.; Haeffner, Fredrik; van der Mei, Farid W.; Hoveyda, Amir H.

    2016-08-01

    Organofluorine compounds are central to modern chemistry, and broadly applicable transformations that generate them efficiently and enantioselectively are in much demand. Here we introduce efficient catalytic methods for the addition of allyl and allenyl organoboron reagents to fluorine-substituted ketones. These reactions are facilitated by readily and inexpensively available catalysts and deliver versatile and otherwise difficult-to-access tertiary homoallylic alcohols in up to 98% yield and >99:1 enantiomeric ratio. Utility is highlighted by a concise enantioselective approach to the synthesis of the antiparasitic drug fluralaner (Bravecto, presently sold as the racemate). Different forms of ammonium-organofluorine interactions play a key role in the control of enantioselectivity. The greater understanding of various non-bonding interactions afforded by these studies should facilitate the future development of transformations that involve fluoroorganic entities.

  3. Bioapplicable, nanostructured and nanocomposite materials for catalytic and biosensor applications

    Science.gov (United States)

    Patel, Alpa C.

    Novel, nanostructured porous nanocomposites and bioapplicable materials have been successfully developed for catalytic, sensor and reinforcement applications. For the first time, porous silver nanoparticle/silica composites were synthesized using a simple method of silver nitrate reduction. The glucose template present inside the mesoporous silica material reduces silver nitrate to silver nanoparticles. The particles thus formed are lodged inside the porous silica matrix. Organic/inorganic hybrid nanofiber mats were fabricated for the first time using the electrospinning technology. The fiber mats have high surface area and good mechanical properties. These fibers mats are then used in reinforcement applications, by utilizing them as fillers in dental materials. The mechanical properties of dental materials thus produced are seen to improve dramatically with the addition of just a small amount of fiber sample. An in-situ method was used to produce silver and gold nanoparticles inside porous silica nanofibers via electrospinning. Metal salts used to produce the nanoparticles are mixed with silica and polymer precursors and spun into fibers. The fibers are then heat-treated to reduce the metal salt into metal nanoparticles. The factors affecting the size and distribution of the nanoparticles inside the porous fibers were studied. The fibers thus produced were then tested for catalytic activity. Horseradish peroxidase (HRP) enzyme was also encapsulated in porous silica nanofibers via electrospinning. The fibers showed significant enhancement in enzyme activity, which was three orders of magnitude greater than that of the non-templated, conventional microporous silica materials. The factors affecting the enzyme activity, like pH, temperature, etc., was also studied. The response time of the encapsulated enzymes to the external reagents was ˜ 2 to 3 seconds, showing high efficiency of the fibers to sensor applications. Finally, the encapsulation and alignment of

  4. Chemistry, phase formation, and catalytic activity of thin palladium-containing oxide films synthesized by plasma-assisted physical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Anders, Andre

    2010-11-26

    The chemistry, microstructure, and catalytic activity of thin films incorporating palladium were studied using scanning and transmission electron microscopies, X-ray diffraction, spectrophotometry, 4-point probe and catalytic tests. The films were synthesized using pulsed filtered cathodic arc and magnetron sputter deposition, i.e. techniques far from thermodynamic equilibrium. Catalytic particles were formed by thermally cycling thin films of the Pd-Pt-O system. The evolution and phase formation in such films as a function of temperature were discussed in terms of the stability of PdO and PtO2 in air. The catalytic efficiency was found to be strongly affected by the chemical composition, with oxidized palladium definitely playing a major role in the combustion of methane. Reactive sputter deposition of thin films in the Pd-Zr-Y-O system allowed us forming microstructures ranging from nanocrystalline zirconia to palladium nanoparticles embedded in a (Zr,Y)4Pd2O matrix. The sequence of phase formation is put in relation to simple thermodynamic considerations.

  5. OPERATING SPECIFICATIONS OF CATALYTIC CLEANING OF GAS FROM BIOMASS GASIFICATION

    Directory of Open Access Journals (Sweden)

    Martin Lisý

    2015-12-01

    Full Text Available The paper focuses on the theoretical description of the cleaning of syngas from biomass and waste gasification using catalytic methods, and on the verification of the theory through experiments. The main obstruction to using syngas from fluid gasification of organic matter is the presence of various high-boiling point hydrocarbons (i.e., tar in the gas. The elimination of tar from the gas is a key factor in subsequent use of the gas in other technologies for cogeneration of electrical energy and heat. The application of a natural or artificial catalyst for catalytic destruction of tar is one of the methods of secondary elimination of tar from syngas. In our experiments, we used a natural catalyst (dolomite or calcium magnesium carbonate from Horní Lánov with great mechanical and catalytic properties, suitable for our purposes. The advantages of natural catalysts in contrast to artificial catalysts include their availability, low purchase prices and higher resilience to the so-called catalyst poison. Natural calcium catalysts may also capture undesired compounds of sulphure and chlorine. Our paper presents a theoretical description and analysis of catalytic destruction of tar into combustible gas components, and of the impact of dolomite calcination on its efficiency. The efficiency of the technology is verified in laboratories. The facility used for verification was a 150 kW pilot gasification unit with a laboratory catalytic filter. The efficiency of tar elimination reached 99.5%, the tar concentration complied with limits for use of the gas in combustion engines, and the tar content reached approximately 35 mg/mn3. The results of the measurements conducted in laboratories helped us design a pilot technology for catalytic gas cleaning.

  6. Pineapple stem bromelain immobilized on different supports: catalytic properties in model wine.

    Science.gov (United States)

    Ilaria, Benucci; Marco, Esti; Katia, Liburdi; Maria Vittoria, Garzillo Anna

    2012-01-01

    Bromelain from pineapple stem has been covalently immobilized on different supports to select the more efficient biocatalyst that should be applied toward unstable proteins in real white wine. In this preliminary study, catalytic properties of different immobilized bromelain forms were compared under wine-like conditions, against a synthetic substrate (Bz-Phe-Val-Arg-pNA).Covalent immobilization affected protease kinetic properties, even if all immobilized forms presented both a better substrate affinity and higher half-life (with the exception of a few procedures) with respect to the free enzyme. Stem bromelain was successfully immobilized on chitosan beads without glutaraldehyde thus yielding a food-safe and promising biocatalyst for unstable real wine future application.

  7. Novel Catalytic Reactor for CO2 Reduction via Sabatier Process Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Precision Combustion, Inc. (PCI) proposes to develop a novel, efficient, and lightweight catalytic Sabatier CO2 methanation unit, capable of converting a mixture of...

  8. Catalytic hydrogenation of carbon monoxide

    Energy Technology Data Exchange (ETDEWEB)

    Wayland, B.B.

    1992-12-01

    This project is focused on developing strategies to accomplish the reduction and hydrogenation of carbon monoxide to produce organic oxygenates at mild conditions. Our approaches to this issue are based on the recognition that rhodium macrocycles have unusually favorable thermodynamic values for producing a series of intermediate implicated in the catalytic hydrogenation of CO. Observations of metalloformyl complexes produced by reactions of H{sub 2} and CO, and reductive coupling of CO to form metallo {alpha}-diketone species have suggested a multiplicity of routes to organic oxygenates that utilize these species as intermediates. Thermodynamic and kinetic-mechanistic studies are used in constructing energy profiles for a variety of potential pathways, and these schemes are used in guiding the design of new metallospecies to improve the thermodynamic and kinetic factors for individual steps in the overall process. Variation of the electronic and steric effects associated with the ligand arrays along with the influences of the reaction medium provide the chemical tools for tuning these factors. Emerging knowledge of the factors that contribute to M-H, M-C and M-O bond enthalpies is directing the search for ligand arrays that will expand the range of metal species that have favorable thermodynamic parameters to produce the primary intermediates for CO hydrogenation. Studies of rhodium complexes are being extended to non-macrocyclic ligand complexes that emulate the favorable thermodynamic features associated with rhodium macrocycles, but that also manifest improved reaction kinetics. Multifunctional catalyst systems designed to couple the ability of rhodium complexes to produce formyl and diketone intermediates with a second catalyst that hydrogenates these imtermediates are promising approaches to accomplish CO hydrogenation at mild conditions.

  9. Ultra Low NOx Catalytic Combustion for IGCC Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Shahrokh Etemad; Benjamin Baird; Sandeep Alavandi; William Pfefferle

    2008-03-31

    In order to meet DOE's goals of developing low-emissions coal-based power systems, PCI has further developed and adapted it's Rich-Catalytic Lean-burn (RCL{reg_sign}) catalytic reactor to a combustion system operating on syngas as a fuel. The technology offers ultra-low emissions without the cost of exhaust after-treatment, with high efficiency (avoidance of after-treatment losses and reduced diluent requirements), and with catalytically stabilized combustion which extends the lower Btu limit for syngas operation. Tests were performed in PCI's sub-scale high-pressure (10 atm) test rig, using a two-stage (catalytic then gas-phase) combustion process for syngas fuel. In this process, the first stage consists of a fuel-rich mixture reacting on a catalyst with final and excess combustion air used to cool the catalyst. The second stage is a gas-phase combustor, where the air used for cooling the catalyst mixes with the catalytic reactor effluent to provide for final gas-phase burnout and dilution to fuel-lean combustion products. During testing, operating with a simulated Tampa Electric's Polk Power Station syngas, the NOx emissions program goal of less than 0.03 lbs/MMBtu (6 ppm at 15% O{sub 2}) was met. NOx emissions were generally near 0.01 lbs/MMBtu (2 ppm at 15% O{sub 2}) (PCI's target) over a range on engine firing temperatures. In addition, low emissions were shown for alternative fuels including high hydrogen content refinery fuel gas and low BTU content Blast Furnace Gas (BFG). For the refinery fuel gas increased resistance to combustor flashback was achieved through preferential consumption of hydrogen in the catalytic bed. In the case of BFG, stable combustion for fuels as low as 88 BTU/ft{sup 3} was established and maintained without the need for using co-firing. This was achieved based on the upstream catalytic reaction delivering a hotter (and thus more reactive) product to the flame zone. The PCI catalytic reactor was also shown

  10. Catalytic Polymer Multilayer Shell Motors for Separation of Organics.

    Science.gov (United States)

    Lin, Zhihua; Wu, Zhiguang; Lin, Xiankun; He, Qiang

    2016-01-26

    A catalytic polymer multilayer shell motor has been developed, which effects fast motion-based separation of charged organics in water. The shell motors are fabricated by sputtering platinum onto the exposed surface of silica templates embedded in Parafilm, followed by layer-by-layer assembly of polyelectrolyte multilayers to the templates. The catalytic shell motors display high bubble propulsion with speeds of up to 260 μm s(-1) (13 body lengths per second). Moreover, the polyelectrolyte multilayers assembled at high pH (pH>9.0) adsorb approximately 89% of dye molecules from water, owing to the electrostatic interaction between the positively charged polymers and the anionic dye molecules, and subsequently release them at neutral pH in a microfluidic device. The efficient propulsion coupled with the effective adsorption behavior of the catalytic shell motors in a microfluidic device results in accelerated separation of organics in water and thus holds considerable promise for water analysis.

  11. A catalytic distillation process for light gas oil hydrodesulfurization

    Energy Technology Data Exchange (ETDEWEB)

    Vargas-Villamil, F.D.; Marroquin, J.O.; Paz, C. de la; Rodriguez, E. [Prog. de Matematicas Aplicadas y Computacion, Prog. de Tratamiento de Crudo Maya, Instituto Mexicano del Petroleo, Mexico City, DF (Mexico)

    2004-07-01

    A light gas oil hydrodesulfurization process via catalytic distillation is developed and compared to a conventional process. By integrating the separation and reaction into a single unit, the catalytic distillation may produce a diesel with low concentration of sulfur compounds at a lower cost than the traditional reaction/separation process. The process proposed in this work is compared to an optimised conventional hydrodesulfurization unit which represents fairly well a plant that belongs to the National System of Refineries. During the optimisation of the conventional process, a compromise is established among the production of diesel and naphtha and the operating costs. The results show that the light gas oil hydrodesulfurization via catalytic distillation is as or more efficient than the conventional process. However, the removal of the sulfur compounds is carried out under less rigorous conditions. This design reduces the fix and operational costs. (author)

  12. 三元催化转化器转化效率影响因素分析%Influencing Factors Analysis of Conversion Efficiency of Three-way Catalytic Converter

    Institute of Scientific and Technical Information of China (English)

    孔祥华; 张海东

    2011-01-01

    针对三元催化转化器的起燃特性,建立转化器的数学模型.给出数值求解方法,讨论了在起燃阶段,进气性质、氢气、孔密度和空速等因素对转化效率的影响.结果表明,增加进气温度,增大孔密度,可缩短起燃时间,提高转化率;适当增大空速有利于提高转化率.%According to the light-off behavior of three-way catalyst, the mathematical model has been developed. Mathematical model was solved by finite difference. It was discussed that inlet gas property, hydrogen, cell density and space velocity can affect the converter efficiency in the light-off period. The results show that light-off time can be reduced by increasing inlet gas temperature and cell density. Conversion efficiency also can be improved by increasing space velocity.

  13. Studies on catalytic reduction of nitrate in groundwater

    Institute of Scientific and Technical Information of China (English)

    GENG Bing; ZHU Yanfang; JIN Zhaohui; LI Tielong; KANG Haiyan; WANG Shuaima

    2007-01-01

    Catalytic reduction of nitrate in groundwater by sodium formate over the catalyst was investigated.Pd-Cu/γ-Al2O3 catalyst was prepared by impregnation and characterized by brunauer-emmett-teller (BET),inductive coupled plasma (ICP),X-ray diffraction (XRD),transmission electron microscopy (TEM) and energy dispersive X-ray (EDX).It was found that total nitrogen was effectively removed from the nitrate solution (100 mg/L) and the removal efficiency was 87%.The catalytic activity was affected by pH,catalyst amount used,concentration of sodium formate,and initial concentration of nitrate.As sodium formate was used as reductant,precise control in the initial pH was needed.Excessively high or low initial pH (7.0 or 3.0) reduced catalytic activity.At initial pH of 4.5,catalytic activity was enhanced by reducing the amount of catalyst,while concentrations of sodium formate increased with a considerable decrease in N2 selectivity.In which case,catalytic reduction followed the first order kinetics.

  14. Reduction of nitrate from groundwater: powder catalysts and catalytic membrane

    Institute of Scientific and Technical Information of China (English)

    CHEN Ying-xu; ZHANG Yan; LIU Hong-yuan

    2003-01-01

    The reduction of nitrate contaminant in groundwater has gained renewed and intensive attention due to the environmental problems and health risks. Catalytic denetrification presents one of the most promising approaches for the removal of nitrate from water. Catalytic nitrate reduction from water by powder catalysts and catalytic membrane in a batch reactor was studied. And the effects of the initial concentration, the amounts of catalyst, and the flux H2 on the nitrate reduction were also discussed. The results demonstrated that nitrate reduction activity and the selectivity to nitrogen gas were mainly controlled by diffusion limitations and the mass transfer of the reactants. The selectivity can improved while retaining a high catalytic activity under controlled diffusion condition or the intensification of the mass transfer, and a good reaction condition. The total nitrogen removal efficiency reached above 80%. Moreover, catalytic membrane can create a high effective gas/liquid/solid interface, and show a good selectivity to nitrogen in comparative with the powder catalyst, the selectivity to nitrogen was improved from 73.4% to 89.4%.

  15. Fluid catalytic cracking of biomass pyrolysis vapors

    Energy Technology Data Exchange (ETDEWEB)

    Mante, Ofei Daku [Virginia Polytechnic Institute and State University, Biological Systems Engineering, Blacksburg, VA (United States); Agblevor, Foster A. [Utah State University, Biological Engineering, Logan, UT (United States); McClung, Ron [BASF Inc, Florham, NJ (United States)

    2011-12-15

    Catalytic cracking of pyrolysis oils/vapors offers the opportunity of producing bio-oils which can potentially be coprocessed with petroleum feedstocks in today's oil refinery to produce transportation fuel and chemicals. Catalyst properties and process conditions are critical in producing and maximizing desired product. In our studies, catalyst matrix (kaolin) and two commercial fluid catalytic cracking (FCC) catalysts, FCC-H and FCC-L, with different Y-zeolite contents were investigated. The catalytic cracking of hybrid poplar wood was conducted in a 50-mm bench-scale bubbling fluidized-bed pyrolysis reactor at 465 C with a weight hourly space velocity of 1.5 h{sup -1}. The results showed that the yields and quality of the bio-oils was a function of the Y-zeolite content of the catalyst. The char/coke yield was highest for the higher Y-zeolite catalyst. The organic liquid yields decreased inversely with increase in zeolite content of the catalyst whereas the water and gas yields increased. Analysis of the oils by both Fourier-transform infrared and {sup 13}C-nuclear magnetic resonance indicated that the catalyst with higher zeolite content (FCC-H) was efficient in the removal of compounds like levoglucosan, carboxylic acids and the conversion of methoxylated phenols to substituted phenols and benzenediols. The cracking of pyrolysis products by kaolin suggests that the activity of the FCC catalyst on biomass pyrolysis vapors can be attributed to both Y-zeolite and matrix. The FCC-H catalyst produced much more improved oil. The oil was low in oxygen (22.67 wt.%), high in energy (29.79 MJ/kg) and relatively stable over a 12-month storage period. (orig.)

  16. PARAMETRIC EVALUATION OF VOC CONVERSION VIA CATALYTIC INCINERATION

    Directory of Open Access Journals (Sweden)

    Kaskantzis Neto G.

    1997-01-01

    Full Text Available Abstract - A pilot-scale catalytic incineration system was used to investigate the effectiveness of catalytic incineration as a means of reducing volatile organic compound (VOC air pollutants. The objectives of the study were: 1 to investigate the effects of operating and design variables on the reduction efficiency of VOCs; and 2 to evaluate reduction efficiencies for specific compounds in different chemical classes. The study results verified that the following factors affect the catalyst performance: inlet temperature, space velocity, compound type, and compound inlet concentration. Tests showed that reduction efficiencies exceeding 98% were possible, given sufficiently high inlet gas temperatures for the following classes of compounds: alcohols, acetates, ketones, hydrocarbons, and aromatics

  17. Catalytic distillation water recovery subsystem

    Science.gov (United States)

    Budininkas, P.; Rasouli, F.

    1985-01-01

    An integrated engineering breadboard subsystem for the recovery of potable water from untreated urine based on the vapor phase catalytic ammonia removal was designed, fabricated and tested. Unlike other evaporative methods, this process catalytically oxidizes ammonia and volatile hydrocarbons vaporizing with water to innocuous products; therefore, no pretreatment of urine is required. Since the subsystem is fabricated from commercially available components, its volume, weight and power requirements are not optimized; however, it is suitable for zero-g operation. The testing program consists of parametric tests, one month of daily tests and a continuous test of 168 hours duration. The recovered water is clear, odorless, low in ammonia and organic carbon, and requires only an adjustment of its pH to meet potable water standards. The obtained data indicate that the vapor phase catalytic ammonia removal process, if further developed, would also be competitive with other water recovery systems in weight, volume and power requirements.

  18. Engineering reactors for catalytic reactions

    Indian Academy of Sciences (India)

    Vivek V Ranade

    2014-03-01

    Catalytic reactions are ubiquitous in chemical and allied industries. A homogeneous or heterogeneous catalyst which provides an alternative route of reaction with lower activation energy and better control on selectivity can make substantial impact on process viability and economics. Extensive studies have been conducted to establish sound basis for design and engineering of reactors for practising such catalytic reactions and for realizing improvements in reactor performance. In this article, application of recent (and not so recent) developments in engineering reactors for catalytic reactions is discussed. Some examples where performance enhancement was realized by catalyst design, appropriate choice of reactor, better injection and dispersion strategies and recent advances in process intensification/ multifunctional reactors are discussed to illustrate the approach.

  19. Catalytic activity of Au nanoparticles

    DEFF Research Database (Denmark)

    Larsen, Britt Hvolbæk; Janssens, Ton V.W.; Clausen, Bjerne;

    2007-01-01

    Au is usually viewed as an inert metal, but surprisingly it has been found that Au nanoparticles less than 3–5 nm in diameter are catalytically active for several chemical reactions. We discuss the origin of this effect, focusing on the way in which the chemical activity of Au may change with par......Au is usually viewed as an inert metal, but surprisingly it has been found that Au nanoparticles less than 3–5 nm in diameter are catalytically active for several chemical reactions. We discuss the origin of this effect, focusing on the way in which the chemical activity of Au may change...... with particle size. We find that the fraction of low-coordinated Au atoms scales approximately with the catalytic activity, suggesting that atoms on the corners and edges of Au nanoparticles are the active sites. This effect is explained using density functional calculations....

  20. Catalytic combustion over high temperature stable metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Berg, M. [TPS Termiska Processer AB, Nykoeping (Sweden)

    1996-12-31

    This thesis presents a study of the catalytic effects of two interesting high temperature stable metal oxides - magnesium oxide and manganese substituted barium hexa-aluminate (BMA) - both of which can be used in the development of new monolithic catalysts for such applications. In the first part of the thesis, the development of catalytic combustion for gas turbine applications is reviewed, with special attention to alternative fuels such as low-BTU gas, e.g. produced in an air blown gasifier. When catalytic combustion is applied for such a fuel, the primary advantage is the possibility of decreasing the conversion of fuel nitrogen to NO{sub x}, and achieving flame stability. In the experimental work, MgO was shown to have a significant activity for the catalytic combustion of methane, lowering the temperature needed to achieve 10 percent conversion by 270 deg C compared with homogeneous combustion.The reaction kinetics for methane combustion over MgO was also studied. It was shown that the heterogeneous catalytic reactions were dominant but that the catalytically initiated homogeneous gas phase reactions were also important, specially at high temperatures. MgO and BMA were compared. The latter showed a higher catalytic activity, even when the differences in activity decreased with increasing calcination temperature. For BMA, CO{sub 2} was the only product detected, but for MgO significant amounts of CO and C{sub 2}-hydrocarbons were formed. BMA needed a much lower temperature to achieve total conversion of other fuels, e.g. CO and hydrogen, compared to the temperature for total conversion of methane. This shows that BMA-like catalysts are interesting for combustion of fuel mixtures with high CO and H{sub 2} content, e.g. gas produced from gasification of biomass. 74 refs

  1. Use of a standardized form for partial budget analyses to assess the feasibility and efficiency of interventions in family poultry operation in 11 African countries

    International Nuclear Information System (INIS)

    The economic evaluation of interventions in management and health of chicken in a backyard production system depends on strict rules for the data acquisition. Here we describe a form for sampling data for partial budget analysis. Eleven countries supplied sufficient data to calculate the economic benefit of certain interventions. For core interventions like Newcastle vaccination, feed supplementation and improved housing of chicks, the return of investment had a factor of 3 to 6, but reaching 18 when vaccine was administered by the farmer. The research contract holders successfully used the data acquisition form and all economic data in this publication are based on it. (author)

  2. Diesel Engine Emission Reduction Using Catalytic Nanoparticles: An Experimental Investigation

    Directory of Open Access Journals (Sweden)

    Ajin C. Sajeevan

    2013-01-01

    Full Text Available Cerium oxide being a rare earth metal with dual valance state existence has exceptional catalytic activity due to its oxygen buffering capability, especially in the nanosized form. Hence when used as an additive in the diesel fuel it leads to simultaneous reduction and oxidation of nitrogen dioxide and hydrocarbon emissions, respectively, from diesel engine. The present work investigates the effect of cerium oxide nanoparticles on performance and emissions of diesel engine. Cerium oxide nanoparticles were synthesized by chemical method and techniques such as TEM, EDS, and XRD have been used for the characterization. Cerium oxide was mixed in diesel by means of standard ultrasonic shaker to obtain stable suspension, in a two-step process. The influence of nanoparticles on various physicochemical properties of diesel fuel has also been investigated through extensive experimentation by means of ASTM standard testing methods. Load test was done in the diesel engine to investigate the effect of nanoparticles on the efficiency and the emissions from the engine. Comparisons of fuel properties with and without additives are also presented.

  3. Study of in vitro toxicity and ex vivo and in vivo efficiency of calixarene galenic forms developed for the treatment of cutaneous contamination due to uranium compounds

    International Nuclear Information System (INIS)

    In case of radiological skin contamination by uranium compounds, the only treatments currently available consist in rinsing the contaminated skin area with water and detergent, or with a calcium salt of diethylene triamine pentaacetic acid (Ca-DTPA) solution. However, these procedures are not specific and no efficient treatment for cutaneous contamination due to uranium exists. In the absence of such treatments, uranium diffusion through the skin is fast, inducing an internal exposure after its distribution inside the body through the bloodstream. One part of the bioavailable uranium is up-taken in target organs which are the kidneys and the skeleton, where its toxic effects occur. Therefore a topical formulation consisting of an oil-in-water nano-emulsion incorporating a tricarboxylic calixarene molecule, as a specific chelating agent for uranium, was previously developed. The work achieved in this thesis aimed at evaluating the ex vivo and in vivo decontamination efficiency of this new emergency treatment on intact and superficially wounded skin. For this purpose, skin excoriation model was used. Reproducible models of superficial wounds consisting of micro-cuts and micro-punctures were also developed in order to evaluate the efficiency of the nano-emulsion on physical wounds such as incisions. These studies showed that the calixarene nano-emulsion could be an efficient decontaminating treatment, less aggressive than using the current treatment: soaped water. Its potential cutaneous toxicity was evaluated on in vitro reconstructed human epidermis using three different toxicity tests (MTT, LDH and IL-1-α). These studies demonstrated that the calixarene nano-emulsion did not induce skin toxicity even after 24 h of exposure time. (author)

  4. Improvement of polycrystalline silicon wafer solar cell efficiency by forming nanoscale pyramids on wafer surface using a self-mask etching technique.

    Science.gov (United States)

    Lin, Hsin-Han; Chen, Wen-Hwa; Hong, Franklin C-N

    2013-05-01

    The creation of nanostructures on polycrystalline silicon wafer surface to reduce the solar reflection can enhance the solar absorption and thus increase the solar-electricity conversion efficiency of solar cells. The self-masking reactive ion etching (RIE) was studied to directly fabricate nanostructures on silicon surface without using a masking process for antireflection purpose. Reactive gases comprising chlorine (Cl2), sulfur hexafluoride (SF6), and oxygen (O2) were activated by radio-frequency plasma in an RIE system at a typical pressure of 120-130 mTorr to fabricate the nanoscale pyramids. Poly-Si wafers were etched directly without masking for 6-10 min to create surface nanostructures by varying the compositions of SF6, Cl2, and O2 gas mixtures in the etching process. The wafers were then treated with acid (KOH:H2O = 1:1) for 1 min to remove the damage layer (100 nm) induced by dry etching. The damage layer significantly reduced the solar cell efficiencies by affecting the electrical properties of the surface layer. The light reflectivity from the surface after acid treatment could be significantly reduced to <10% for the wavelengths between 500 and 900 nm. The effects of RIE and surface treatment conditions on the surface nanostructures and the optical performance as well as the efficiencies of solar cells will be presented and discussed. The authors have successfully fabricated large-area (156 × 156 mm(2)) subwavelength antireflection structure on poly-Si substrates, which could improve the solar cell efficiency reproducibly up to 16.27%, higher than 15.56% using wet etching. PMID:23847751

  5. Use of the latest induction technology for permanent enhancement of resources efficiency in heavy forming; Einsatz neuester Induktionstechnik zur nachhaltigen Steigerung der Ressourceneffizienz in der Massivumformung

    Energy Technology Data Exchange (ETDEWEB)

    Gies, Jochen; Schibisch, Dirk M. [SMS Elotherm GmbH, Remscheid (Germany)

    2011-06-15

    The ever increasing cost pressure in the forging industry forces the manufacturers of forging equipment to develop innovative concepts, which preserve existing resources. These new concepts must respect the OEM's demands for a reduction of CO{sub 2} emissions. The increase in energy efficiency of induction heating systems plays a decisive role in meeting these demands and the development of the intelligent zone control iZone trademark is an important step. (orig.)

  6. Catalytic converter for next generation turbine engines

    Energy Technology Data Exchange (ETDEWEB)

    Saruhan, B.; Schulz, U.; Leyens, C. [German Aerospace Center (DLR), Inst. of Materials Research, Cologne (Germany)

    2004-07-01

    EB-PVD thermal barrier coatings (TBCs) are used on advanced turbine blades to increase the engine efficiency and improve the blade performance. partially yttria stabilized zirconia (PYSZ) is the standard material for current TBC applications. Lower thermal stability of the PYSZ-based TBCs, however, seriously affects the performance at demanding service temperatures. For the new generation turbines where higher operating gas temperatures (> 1200 C) are to expect, the performance of turbine blades can be improved by replacing the state-art-of-material PYSZ with superior thermal barrier coatings which belong to different crystal structures such as magnetoplumbite. Magnetoplumbite structure through its interlocking grain morphology and unique crystal structure provides essentially a sintering resistant, low thermal conductive layer, but also imparts a catalytic layer to reduce the environmentally harmful substances produced during propulsion and increase the catalytic performance. The complex structures of these compounds make it difficult to realize by conventional methods and requires careful adjustment of process parameters. The morphology and crystallographic aspects of these coatings as well as the mechanisms controlling the improvement are highlighted. (orig.)

  7. Computational and Physical Analysis of Catalytic Compounds

    Science.gov (United States)

    Wu, Richard; Sohn, Jung Jae; Kyung, Richard

    2015-03-01

    Nanoparticles exhibit unique physical and chemical properties depending on their geometrical properties. For this reason, synthesis of nanoparticles with controlled shape and size is important to use their unique properties. Catalyst supports are usually made of high-surface-area porous oxides or carbon nanomaterials. These support materials stabilize metal catalysts against sintering at high reaction temperatures. Many studies have demonstrated large enhancements of catalytic behavior due to the role of the oxide-metal interface. In this paper, the catalyzing ability of supported nano metal oxides, such as silicon oxide and titanium oxide compounds as catalysts have been analyzed using computational chemistry method. Computational programs such as Gamess and Chemcraft has been used in an effort to compute the efficiencies of catalytic compounds, and bonding energy changes during the optimization convergence. The result illustrates how the metal oxides stabilize and the steps that it takes. The graph of the energy computation step(N) versus energy(kcal/mol) curve shows that the energy of the titania converges faster at the 7th iteration calculation, whereas the silica converges at the 9th iteration calculation.

  8. A Temperature Window for the Synthesis of Single-Walled Carbon Nanotubes by Catalytic Chemical Vapor Deposition of CH4over Mo2-Fe10/MgO Catalyst

    Directory of Open Access Journals (Sweden)

    Yu Ouyang

    2009-01-01

    Full Text Available Abstract A temperature window for the synthesis of single-walled carbon nanotubes by catalytic chemical vapor deposition of CH4over Mo2-Fe10/MgO catalyst has been studied by Raman spectroscopy. The results showed that when the temperature is lower than 750 °C, there were few SWCNTs formed, and when the temperature is higher than 950 °C, mass amorphous carbons were formed in the SWCNTs bundles due to the self-decomposition of CH4. The temperature window of SWCNTs efficient growth is between 800 and 950 °C, and the optimum growth temperature is about 900 °C. These results were supported by transmission electron microscope images of samples formed under different temperatures. The temperature window is important for large-scale production of SWCNTs by catalytic chemical vapor deposition method.

  9. Facile synthesis of polypyrrole functionalized nickel foam with catalytic activity comparable to Pt for the poly-generation of hydrogen and electricity

    Science.gov (United States)

    Tang, Tiantian; Li, Kan; Shen, Zhemin; Sun, Tonghua; Wang, Yalin; Jia, Jinping

    2016-01-01

    Polypyrrole functionalized nickel foam is facilely prepared through the potentiostatic electrodeposition. The PPy-functionalized Ni foam functions as a hydrogen-evolution cathode in a rotating disk photocatalytic fuel cell, in which hydrogen energy and electric power are generated by consuming organic wastes. The PPy-functionalized Ni foam cathode exhibits stable catalytic activities after thirteen continuous runs. Compared with net or plate structure, the Ni foam with a unique three-dimensional reticulate structure is conducive to the electrodeposition of PPy. Compared with Pt-group electrode, PPy-coated Ni foam shows a satisfactory catalytic performance for the H2 evolution. The combination of PPy and Ni forms a synergistic effect for the rapid trapping and removal of proton from solution and the catalytic reduction of proton to hydrogen. The PPy-functionalized Ni foam could be applied in photocatalytic and photoelectrochemical generation of H2. In all, we report a low cost, high efficient and earth abundant PPy-functionalized Ni foam with a satisfactory catalytic activities comparable to Pt for the practical application of poly-generation of hydrogen and electricity.

  10. Collaborative form(s)

    DEFF Research Database (Denmark)

    Gunn, Wendy

    the process of research rather than its object. In its temporal orientation, anthropology by means of design moves, ‘…forward with people in tandem with their desires and aspirations rather than going back over times passed’ (ibid 2013: 141). Doing design by means of anthropology takes as its most fundamental......Gunn asks us to consider beauty as collaborative forms of action generated by moving between design by means of anthropology and anthropology by means of design. Specifically, she gives focus to play-like reflexions on practices of designing energy products, systems and infrastructure. Design...

  11. Catalytic properties of niobium compounds

    International Nuclear Information System (INIS)

    The catalytic activity and selectivity of niobium compounds including oxides, salts, organometallic compounds and others are outlined. The application of these compounds as catalysts to diversified reactions is reported. The nature and action of niobium catalysts are characteristic and sometimes anomalous, suggesting the necessity of basic research and the potential use as catalysts for important processes in the chemical industry. (Author)

  12. Simple, chemoselective, catalytic olefin isomerization.

    Science.gov (United States)

    Crossley, Steven W M; Barabé, Francis; Shenvi, Ryan A

    2014-12-01

    Catalytic amounts of Co(Sal(tBu,tBu))Cl and organosilane irreversibly isomerize terminal alkenes by one position. The same catalysts effect cycloisomerization of dienes and retrocycloisomerization of strained rings. Strong Lewis bases like amines and imidazoles, and labile functionalities like epoxides, are tolerated.

  13. TESTING THE WEAK-FORM EFFICIENCY OF THE ROMANIAN CAPITAL MARKET BY ASSESSING THE RANDOM WALK-LIKE BEHAVIOUR OF STOCK PRICES

    Directory of Open Access Journals (Sweden)

    PAŞCA LUCIAN

    2015-04-01

    Full Text Available This paper attempts to test the efficiency of the Romanian Capital Market by assessing some basic statistical properties of prices for the ten most liquid stocks listed on the Bucharest Stock Exchange. More specifically, by testing if stock price series exhibit a random walk-like behaviour. For robustness of the results, two unit root tests—the Augmented Dickey-Fuller and the Kwiatkowski-Phillips-Schmidt-Shin—are used to measure stationarity for both prices and returns, and determine if price dynamics is determined by an order one integrated process (a proxy for the random walk. Further Lo and MacKinley‘s Variance Ratio Test is applied to study if the variance of returns is a linear time-dependent function (a well-known property of a random variable. The analysis is done for a period between 15 October 1997, or the listing date on the stock exchange, respectively, and 10 April 2013, for both daily and weekly observations. Furthermore, to take into account the distortive effects of the financial turmoil from 2007-2009 on market efficiency, a separate analysis has been conducted for two sub-periods, pre- and post-recession, respectively.

  14. Catalytic reactor for low-Btu fuels

    Science.gov (United States)

    Smith, Lance; Etemad, Shahrokh; Karim, Hasan; Pfefferle, William C.

    2009-04-21

    An improved catalytic reactor includes a housing having a plate positioned therein defining a first zone and a second zone, and a plurality of conduits fabricated from a heat conducting material and adapted for conducting a fluid therethrough. The conduits are positioned within the housing such that the conduit exterior surfaces and the housing interior surface within the second zone define a first flow path while the conduit interior surfaces define a second flow path through the second zone and not in fluid communication with the first flow path. The conduit exits define a second flow path exit, the conduit exits and the first flow path exit being proximately located and interspersed. The conduits define at least one expanded section that contacts adjacent conduits thereby spacing the conduits within the second zone and forming first flow path exit flow orifices having an aggregate exit area greater than a defined percent of the housing exit plane area. Lastly, at least a portion of the first flow path defines a catalytically active surface.

  15. Catalytic combustion in gas stoves - Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Hjelm, Anna-Karin [CATATOR AB, Lund (Sweden)

    2003-06-01

    Several independent studies show that gas stoves to some degree contribute to the indoor emissions of NO{sub x} especially in situations were the ventilation flow is poor. The peak-NO{sub x} concentrations can reach several hundred ppb but the integral concentration seldom exceeds about 20 - 50 ppb, which corresponds to an indoor-outdoor ratio of about 1 - 2.5. Epidemiological studies indicate increasing problems with respiratory symptoms in sensitive people at concentrations as low as 15 ppb of NO{sub 2}. Consequently, the NO{sub x}-concentration in homes where gas stoves are used is high enough to cause health effects. However, in situations where the ventilation flow is high (utilisation of ventilation hoods) the NO{sub x}-emissions are not likely to cause any health problems. This study has been aimed at investigating the possibilities to reduce the NO{sub x} emissions from gas stoves by replacing the conventional flame combustion with catalytic combustion. The investigation is requested by Swedish Gas Center, and is a following-up work of an earlier conducted feasibility study presented in April-2002. The present investigation reports on the possibility to use cheap and simple retro-fit catalytic design suggestions for traditional gas stoves. Experiments have been conducted with both natural and town gas, and parameters such as emissions of NO{sub x}, CO and unburned fuel gas and thermal efficiency, etc, have been examined and are discussed. The results show that it is possible to reduce the NO{sub x} emissions up to 80% by a simple retro-fit installation, without decreasing the thermal efficiency of the cooking plate. The measured source strengths correspond to indoor NO{sub x} concentrations that are below or equal to the average outdoor concentration, implying that no additional detrimental health effects are probable. The drawback of the suggested installations is that the concentration of CO and in some cases also CH{sub 4} are increased in the flue gases

  16. Fuel Flexible, Low Emission Catalytic Combustor for Opportunity Fuel Applications

    Energy Technology Data Exchange (ETDEWEB)

    Eteman, Shahrokh

    2013-06-30

    Limited fuel resources, increasing energy demand and stringent emission regulations are drivers to evaluate process off-gases or process waste streams as fuels for power generation. Often these process waste streams have low energy content and/or highly reactive components. Operability of low energy content fuels in gas turbines leads to issues such as unstable and incomplete combustion. On the other hand, fuels containing higher-order hydrocarbons lead to flashback and auto-ignition issues. Due to above reasons, these fuels cannot be used directly without modifications or efficiency penalties in gas turbine engines. To enable the use of these wide variety of fuels in gas turbine engines a rich catalytic lean burn (RCL®) combustion system was developed and tested in a subscale high pressure (10 atm.) rig. The RCL® injector provided stability and extended turndown to low Btu fuels due to catalytic pre-reaction. Previous work has shown promise with fuels such as blast furnace gas (BFG) with LHV of 85 Btu/ft3 successfully combusted. This program extends on this work by further modifying the combustor to achieve greater catalytic stability enhancement. Fuels containing low energy content such as weak natural gas with a Lower Heating Value (LHV) of 6.5 MJ/m3 (180 Btu/ft3 to natural gas fuels containing higher hydrocarbon (e.g ethane) with LHV of 37.6 MJ/m3 (1010 Btu/ft3) were demonstrated with improved combustion stability; an extended turndown (defined as the difference between catalytic and non-catalytic lean blow out) of greater than 250oF was achieved with CO and NOx emissions lower than 5 ppm corrected to 15% O2. In addition, for highly reactive fuels the catalytic region preferentially pre-reacted the higher order hydrocarbons with no events of flashback or auto-ignition allowing a stable and safe operation with low NOx and CO emissions.

  17. Development of an efficient E. coli expression and purification system for a catalytically active, human Cullin3-RINGBox1 protein complex and elucidation of its quaternary structure with Keap1

    International Nuclear Information System (INIS)

    Research highlights: → A novel expression strategy was used to purify Cul3-Rbx1 from E. coli. → The Cul3-Rbx1 complex is fully active and catalyzes ubiquitination of Nrf2 in vitro. → Cul3, Rbx1, and Keap1 form a complex with unique stoichiometry of 1:1:2. -- Abstract: The Cullin3-based E3 ubiquitin ligase complex is thought to play an important role in the cellular response to oxidative stress and xenobiotic assault. While limited biochemical studies of the ligase's role in these complex signaling pathways are beginning to emerge, structural studies are lagging far behind due to the inability to acquire sufficient quantities of full-length, highly pure and active Cullin3. Here we describe the design and construction of an optimized expression and purification system for the full-length, human Cullin3-RINGBox 1 (Rbx1) protein complex from Escherichia coli. The dual-expression system is comprised of codon-optimized Cullin3 and Rbx1 genes co-expressed from a single pET-Duet-1 plasmid. Rapid purification of the Cullin3-Rbx1 complex is achieved in two steps via an affinity column followed by size-exclusion chromatography. Approximately 15 mg of highly pure and active Cullin3-Rbx1 protein from 1 L of E. coli culture can be achieved. Analysis of the quaternary structure of the Cullin3-Rbx1 and Cullin3-Rbx1-Keap1 complexes by size-exclusion chromatography and analytical ultracentrifugation indicates a 1:1 stoichiometry for the Cullin3-Rbx1 complex (MW = 111 kDa), and a 1:1:2 stoichiometry for the Cullin3-Rbx1-Keap1 complex (MW = 280 kDa). This latter complex has a novel quaternary structural organization for cullin E3 ligases, and it is fully active based on an in vitro Cullin3-Rbx1-Keap1-Nrf2 ubiquitination activity assay that was developed and optimized in this study.

  18. Temperature-driven switching of the catalytic activity of artificial glutathione peroxidase by the shape transition between the nanotubes and vesicle-like structures.

    Science.gov (United States)

    Wang, Liang; Zou, Huixin; Dong, Zeyuan; Zhou, Lipeng; Li, Jiaxi; Luo, Quan; Zhu, Junyan; Xu, Jiayun; Liu, Junqiu

    2014-04-15

    Smart supramolecular nanoenzymes with temperature-driven switching property have been successfully constructed by the self-assembly of supra-amphiphiles formed by the cyclodextrin-based host-guest chemistry. The self-assembled nanostructures were catalyst-functionalized and thermosensitively-functionalized through conveniently linking the catalytic center of glutathione peroxidase and thermosensitive polymer to the host cyclodextrin molecules.The ON-OFF switches for the peroxidase activity by reversible transformation of nanostructures from tube to sphere have been achieved through changing the temperature. We anticipate that such intelligent enzyme mimics could be developed to use in an antioxidant medicine with controlled catalytic efficiency according to the needs of the human body in the future. PMID:24654792

  19. Catalytic Hydrothermal Gasification

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, Douglas C.

    2015-05-31

    The term “hydrothermal” used here refers to the processing of biomass in water slurries at elevated temperature and pressure to facilitate the chemical conversion of the organic structures in biomass into useful fuels. The process is meant to provide a means for treating wet biomass materials without drying and to access ionic reaction conditions by maintaining a liquid water processing medium. Typical hydrothermal processing conditions are 523-647K of temperature and operating pressures from 4-22 MPa of pressure. The temperature is sufficient to initiate pyrolytic mechanisms in the biopolymers while the pressure is sufficient to maintain a liquid water processing phase. Hydrothermal gasification is accomplished at the upper end of the process temperature range. It can be considered an extension of the hydrothermal liquefaction mechanisms that begin at the lowest hydrothermal conditions with subsequent decomposition of biopolymer fragments formed in liquefaction to smaller molecules and eventually to gas. Typically, hydrothermal gasification requires an active catalyst to accomplish reasonable rates of gas formation from biomass.

  20. Catalytic Conversion of Carbohydrates

    DEFF Research Database (Denmark)

    Osmundsen, Christian Mårup

    Modern civilization is dependent on oil to supply energy for power, heating and transportation and carbon for the production of the plethora of chemicals needed. Oil is however a limited resource and alternatives need to be identified before we freeze in the dark [1]. This thesis deals with the p......Modern civilization is dependent on oil to supply energy for power, heating and transportation and carbon for the production of the plethora of chemicals needed. Oil is however a limited resource and alternatives need to be identified before we freeze in the dark [1]. This thesis deals......-BEA was studied using DFT calculations, which indicate that the strongest, and most stable, acid site is formed through the introduction of a silicon vacancy adjacent to the tin site. Aromatics are an important class of compounds. In particular benzene, toluene and p-xylene finds use in a wide range of industries...... a renewable route to aromatics. The conversion of biomass by high temperature processes is a desirable prospect due to the high volumetric production rates which can be achieved, and the ability of these types of processes to convert a wide range of substrates. Current processes however typically have rather...

  1. Short hydrogen bonds in the catalytic mechanism of serine proteases

    Directory of Open Access Journals (Sweden)

    VLADIMIR LESKOVAC

    2008-04-01

    Full Text Available The survey of crystallographic data from the Protein Data Bank for 37 structures of trypsin and other serine proteases at a resolution of 0.78–1.28 Å revealed the presence of hydrogen bonds in the active site of the enzymes, which are formed between the catalytic histidine and aspartate residues and are on average 2.7 Å long. This is the typical bond length for normal hydrogen bonds. The geometric properties of the hydrogen bonds in the active site indicate that the H atom is not centered between the heteroatoms of the catalytic histidine and aspartate residues in the active site. Taken together, these findings exclude the possibility that short “low-barrier” hydrogen bonds are formed in the ground state structure of the active sites examined in this work. Some time ago, it was suggested by Cleland that the “low-barrier hydrogen bond” hypothesis is operative in the catalytic mechanism of serine proteases, and requires the presence of short hydrogen bonds around 2.4 Å long in the active site, with the H atom centered between the catalytic heteroatoms. The conclusions drawn from this work do not exclude the validity of the “low-barrier hydrogen bond” hypothesis at all, but they merely do not support it in this particular case, with this particular class of enzymes.

  2. Natural gas combustion in a catalytic turbulent fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Foka, M.; Chaouki, J.; Guy, C.; Klvana, D. [Ecole Polytechnique de Montreal, Quebec (Canada). Dept. of Chemical Engineering

    1994-12-01

    Catalytic fluidized bed combustion of natural gas is shown to be an emerging technology capable of meeting all environmental constraints as far as nitrogen oxides and carbon monoxide are concerned. This technology uses powder catalysts in the turbulent flow regime where the gas-solid contact is optimal so as to maintain a high combustion efficiency. In fact, the catalytic combustion carried out in both the bubbling and the turbulent regimes at 450-500{sup o}C shows that the turbulent regime is more favorable. A single phase plug flow model with axial dispersion is shown to fit satisfactorily the data obtained at 500{sup o}C where the combustion efficiency is very good. A self-sustained combustion was achieved with a mixture of 4% methane at around 500{sup o}C with a complete conversion of methane and a zero emission of NO{sub x} and CO. (author)

  3. Catalytic hydrocarbon reactions over supported metal oxides. Final report, August 1, 1986--July 31, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Ekerdt, J.G.

    1995-10-20

    Oxide catalysis plays a central role in hydrocarbon processing and improvements in catalytic activity or selectivity are of great technological importance because these improvements will translate directly into more efficient utilization of hydrocarbon supplies and lower energy consumption in separation processes. An understanding of the relationships between surface structure and catalytic properties is needed to describe and improve oxide catalysts. The approach has been to prepare supported oxides that have a specific structure and oxidation state and then employ these structures in reaction studies. The current research program is focused on studying the fundamental relationships between structure and reactivity for two important reactions that are present in many oxide-catalyzed processes, partial oxidation and carbon-carbon bond formation. During the course of these studies the author has: (1) developed methods to form and stabilize various Mo and W oxide structures on silica; (2) studied C-H abstraction reactions over the fully oxidized cations; (3) studied C-C bond coupling by metathesis and reductive coupling of aldehydes and ketones over reduced cation structures; and (4) initiated a study of hydrogenation and hydrogenolysis over reduced cation structures.

  4. In situ generation of electron acceptor for photoelectrochemical biosensing via hemin-mediated catalytic reaction.

    Science.gov (United States)

    Zang, Yang; Lei, Jianping; Zhang, Lei; Ju, Huangxian

    2014-12-16

    A novel photoelectrochemical sensing strategy is designed for DNA detection on the basis of in situ generation of an electron acceptor via the catalytic reaction of hemin toward H2O2. The photoelectrochemical platform was established by sequential assembly of near-infrared CdTe quantum dots, capture DNA, and a hemin-labeled DNA probe to form a triple-helix molecular beacon (THMB) structure on an indium tin oxide electrode. According to the highly catalytic capacity of hemin toward H2O2, a photoelectrochemical mechanism was then proposed, in which the electron acceptor of O2 was in situ-generated on the electrode surface, leading to the enhancement of the photocurrent response. The utilization of CdTe QDs can extend the absorption edge to the near-infrared band, resulting in an increase in the light-to-electricity efficiency. After introducing target DNA, the THMB structure is disassembled and releases hemin and, thus, quenches the photocurrent. Under optimized conditions, this biosensor shows high sensitivity with a linear range from 1 to 1000 pM and detection limit of 0.8 pM. Moreover, it exhibits good performance of excellent selectivity, high stability, and acceptable fabrication reproducibility. This present strategy opens an alternative avenue for photoelectrochemical signal transduction and expands the applications of hemin-based materials in photoelectrochemical biosensing and clinical diagnosis. PMID:25393151

  5. Commercial Test of Flexible Dual-Riser Catalytic Cracking Process

    Institute of Scientific and Technical Information of China (English)

    Tang Haitao; Wang Longyan; Wang Guoliang; Zhang Lixin; Wei Jialu; Chen Zhenghong; Teng Tiancan; Sun Zhonghang

    2003-01-01

    The technical features and commercial test results of flexible dual-riser fluidized catalytic cracking(FDFCC) process are presented for refiners to choose an efficient process to upgrade FCC naphtha and boostpropylene production in a RFCC unit. The commercial test results indicate that the olefin content of catalyti-25% and RON increased by 0.5-2 units in a RFCC unit. In addition, propylene yield and the production ratioof diesel to gasoline can also be remarkably enhanced in the RFCC unit.

  6. Highly Catalytic Nanodots with Renal Clearance for Radiation Protection

    OpenAIRE

    Zhang, Xiao-Dong; Zhang, Jinxuan; Wang, Junying; Yang, Jiang; Chen, Jie; Shen, Xiu; Deng, Jiao; Deng, Dehui; Long, Wei; Sun, Yuan-Ming; Liu, Changlong; Li, Meixian

    2016-01-01

    Ionizing radiation (gamma and x-ray) is widely used in industry and medicine, but it can also pose a significant hazardous effect on health and induce cancer, physical deformity and even death, due to DNA damages and invasion of free radicals. There is therefore an urgent unmet demand in designing highly efficient radioprotectants with synergetic integration of effective renal clearance and low toxicity. In this study, we designed ultrasmall (sub-5 nm) highly catalytically active and cysteine...

  7. Contact structure for use in catalytic distillation

    Science.gov (United States)

    Jones, Jr., Edward M.

    1984-01-01

    A method for conducting catalytic chemical reactions and fractionation of the reaction mixture comprising feeding reactants into a distillation column reactor contracting said reactant in liquid phase with a fixed bed catalyst in the form of a contact catalyst structure consisting of closed porous containers containing the catatlyst for the reaction and a clip means to hold and support said containers, which are disposed above, i.e., on the distillation trays in the tower. The trays have weir means to provide a liquid level on the trays to substantially cover the containers. In other words, the trays function in their ordinary manner with the addition thereto of the catalyst. The reaction mixture is concurrently fractionated in the column.

  8. Flame assisted synthesis of catalytic ceramic membranes

    DEFF Research Database (Denmark)

    Johansen, Johnny; Mosleh, Majid; Johannessen, Tue;

    2004-01-01

    will be spherical due to the fast coalescence at the high temperatures in the flame. The primary product from the flame pyrolysis is an aerosol of metal oxide nanoparticles. The aerosol gas from the flame can be utilized for several different purposes, depending on the precursors fed to the flame. With the present...... technology it is possible to make supported catalysts, composite metal oxides, catalytically active surfaces, and porous ceramic membranes. Membrane layers can be formed by using a porous substrate tube (or surface) as a nano-particle filter. The aerosol gas from the flame is led through a porous substrate...... tube, where a part of the gas is sucked through the wall of the substrate, thereby creating a thin filter cake on the inner surface of the substrate tube. The top-layer can be deposited directly on a coarse pore structure. Since the Brownian motion of the aerosol particles is fast compared to the fluid...

  9. β-FeOOH/蜂窝陶瓷催化臭氧化高效去除饮用水中有机污染物%Efficient removal of organic pollutants in drinkingwater by catalytic ozonation catalyst β-FeOOH/ceramic honeycomb

    Institute of Scientific and Technical Information of China (English)

    胡建朝; 聂玉伦; 胡春; 郑红

    2012-01-01

    β-FeOOH/ceramic honeycomb(β-FeOOH/CH) was prepared by the following procedure: ceramic honeycomb was washcoated by Al2O3 via sol-gel method with boehmite as precursor,which was further modified by loading β-FeOOH(as active species).In comparison with ozonation process,the catalyst exhibited a higher catalytic activity for the degradation of 2,4-dichlorophenoxyacetic acid(2,4-D) in a semi-continuous laboratory reactor.At a reaction time of 20 min,2,4-D was completely destroyed and about 80% of the TOC was removed under the optimum conditions.Moreover,the effects of water flow speed and the initial concentration of organic pollutants et al.on the catalytic ozonation efficiency were also studied in detail.The results indicated that ozone could be efficiently decomposed over β-FeOOH/CH,leading to the highly efficient removal of organic pollutants such as atrazine and epichlorohydrin.Furthermore,β-FeOOH/CH had an excellent long-term stability and no obviously deactivation in 30 successive cycles.Therefore,β-FeOOH/CH has a promising application in drinking water treatment.%市售蜂窝陶瓷经过氧化铝涂层后,进一步负载β-FeOOH活性组分,制得改性蜂窝陶瓷催化剂(β-FeOOH/Ce-ramic honeycomb,β-FeOOH/CH)。与单独臭氧氧化相比,基于该催化剂的固定床反应装置体现出更好的臭氧化活性,反应20 min后,水中的2,4-二氯苯氧乙酸(2,4-D)就可以完全去除,其矿化效率也可以达到80%以上。进一步考察了进水流速、有机物浓度等因素对多相催化臭氧化效率的影响,结果表明:β-FeOOH/CH可以显著提高臭氧的利用效率,能够有效去除水中包括2,4-D在内的多种有机污染物,而且催化剂可以重复使用,在长期的运行实验中其催化性能没有明显下降,该反应装置在饮用水深度处理领域具有很好的应用潜力。

  10. Effect of the efficiency of N by use of different forms of fertilizer application in ground, evaluated by means of the isotopic technique and the N absorbed by the cultivation

    International Nuclear Information System (INIS)

    The determination of the efficiency in the use of nitrogen fertilizers, constitutes one of the important aspects that should be considered in the process of the appropriated element doses recommendation. The form of fertilizer placement is a very important aspect that affects the efficiency, and its evaluation is the main objective of the present work, by means of the Direct Method with the use of N15, and the Indirect Method by means of the N-absorbed by fertilized plants and no fertilized ones. The study was carried out in a Fluventic Haplustoll soil, located in San Carlos, Cojedes State, where three forms of fertilizer placement were evaluated : 1) broadcasting application and incorporation with harrows pass (V/R); 2) broadcasting application and incorporation with disc harrows pass (V/B); 3) application band fertilizer (B); 4) without fertilization; parcels of 200 m2 were sown with corn (Zea mayz), and received an application equivalent to 120 Kg N/ha, in the form of urea. In each of the fertilized parcels, three microparcels of 2,56 m2 were settled down where the normal urea was substituted by enriched urea with N15 to 3% exc. During the crop cycle, the contents N-mineral extracted with KCl(2M) were evaluated and finally the production of dry matter, grain, and the contents of N-total and N15. It was found that the efficiency in the N-fertilizer recovery, by means of the Direct Method, fluctuated between 18.8 and 23,7%, although the grain production was high, fluctuating between 6541 and 6007 kg/ha, suggesting little use of N-fertilizer although a significant use or the soil N. On the other hand, one observes that the processes of mineralization/inmobilization are affected by the application of N, highlighting the importance of their knowledge to improve the efficiency of the use of N-fertilizer and the N coming from soils

  11. Catalytic pyrolysis of Pubescens to phenols over Ni/C catalyst

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The pyrolysis of Pubescens over Ni/C catalyst was studied at 350°C in H2 flow.The presence of Ni/C catalyst efficiently improved the degradation of raw materials,and produced bio-oil with high content of phenols but low contents of acetic acid,furfural and water.In the reaction,Ni/C catalyst plays the role of catalytic decomposition and catalytic hydrogenation.The existence of the carbon carrier favors the formation of active Ni in small sizes with more defects,which results in high catalytic activity of Ni in biomass decomposition and selective production of phenols.

  12. Catalytic combustion in small wood burning appliances

    Energy Technology Data Exchange (ETDEWEB)

    Oravainen, H. [VTT Energy, Jyvaeskylae (Finland)

    1996-12-31

    There is over a million hand fired small heating appliances in Finland where about 5,4 million cubic meters of wood fuel is used. Combustion in such heating appliances is a batch-type process. In early stages of combustion when volatiles are burned, the formation of carbon monoxide (CO) and other combustible gases are difficult to avoid when using fuels that have high volatile matter content. Harmful emissions are formed mostly after each fuel adding but also during char burnout period. When the CO-content in flue gases is, say over 0.5 %, also other harmful emissions will be formed. Methane (CH{sub 4}) and other hydrocarbons are released and the amount of polycyclic aromatic hydrocarbons (PAH)-compounds can be remarkable. Some PAH-compounds are very carcinogenic. It has been estimated that in Finland even more than 90 % of hydrocarbon and PAH emissions are due to small scale wood combustion. Emissions from transportation is excluded from these figures. That is why wood combustion has a net effect on greenhouse gas phenomena. For example carbon monoxide emissions from small scale wood combustion are two fold compared to that of energy production in power plants. Methane emission is of the same order as emission from transportation and seven fold compared with those of energy production. Emissions from small heating appliances can be reduced by developing the combustion techniques, but also by using other means, for example catalytic converters. In certain stages of the batch combustion, temperature is not high enough, gas mixing is not good enough and residence time is too short for complete combustion. When placed to a suitable place inside a heating appliance, a catalytic converter can oxidize unburned gases in the flue gas into compounds that are not harmful to the environment. (3 refs.)

  13. Catalytic Fast Pyrolysis: A Review

    Directory of Open Access Journals (Sweden)

    Theodore Dickerson

    2013-01-01

    Full Text Available Catalytic pyrolysis is a promising thermochemical conversion route for lignocellulosic biomass that produces chemicals and fuels compatible with current, petrochemical infrastructure. Catalytic modifications to pyrolysis bio-oils are geared towards the elimination and substitution of oxygen and oxygen-containing functionalities in addition to increasing the hydrogen to carbon ratio of the final products. Recent progress has focused on both hydrodeoxygenation and hydrogenation of bio-oil using a variety of metal catalysts and the production of aromatics from bio-oil using cracking zeolites. Research is currently focused on developing multi-functional catalysts used in situ that benefit from the advantages of both hydrodeoxygenation and zeolite cracking. Development of robust, highly selective catalysts will help achieve the goal of producing drop-in fuels and petrochemical commodities from wood and other lignocellulosic biomass streams. The current paper will examine these developments by means of a review of existing literature.

  14. Light extraction efficiency enhancement of GaN-based blue LEDs based on ITO/ InxO ohmic contacts with microstructure formed by annealing in oxygen.

    Science.gov (United States)

    Luo, Yi; Bai, Yiming; Han, Yanjun; Li, Hongtao; Wang, Lai; Wang, Jian; Sun, Changzheng; Hao, Zhibiao; Xiong, Bing

    2016-05-16

    Indium tin oxide (ITO)/ indium oxide (InxO) double layer structure was adopted as the transparent conduction and light scattering function layer to improve the light extraction efficiency of the GaN-based blue LEDs. The double layer structure was first deposited in one run by electron beam evaporation using ITO and Indium as the source respectively, and then annealed in an oxygen environment. This method can fabricate transparent electrode with microstructure and low specific contact resistivity one time free from lithography and etching, which makes the fabrication process simple and at a ower cost. For the 220 nm ITO/ 170 nm InxO double layer sample annealed at 600°C for 15 min in oxygen, measurement results show that its root mean square of roughness of the surface microstructure can be as high as 85.2 nm which introduces the strongest light scattering. Its light transmittance at 450 nm can maintain 92.4%. At the same time, it can realize lower specific contact resistivity with p-InGaN. Compared with the GaN-based blue LEDs with only 220 nm ITO electrode, the light output power of the LEDs with 220 nm ITO/ 170 nm InxO double layer structure can be increased about 58.8%, and working voltage at 20 mA injection current is decreased about 0.23 V due to the enhanced current spreading capability. The light output power improvement is also theoretically convinced by finite difference time domain simulations. PMID:27409953

  15. Combined catalytic converter and afterburner

    Energy Technology Data Exchange (ETDEWEB)

    Ma, T.T.-H.

    1994-11-30

    This patent describes the combined use of a catalytic converter and afterburner. An afterburner chamber and a catalyst matrix are disposed in series within a casing. A combustible premixed charge is ignited in the afterburner chamber before it enters the catalyst matrix. This invention overcomes the problem encountered in previous designs of some of the premixed charge passing unreacted through the device unless a very long afterburner chamber is used. (UK)

  16. Catalytic activities of a cocaine hydrolase engineered from human butyrylcholinesterase against (+)- and (−)-cocaine

    OpenAIRE

    Xue, Liu; Hou, Shurong; Wenchao YANG; Fang, Lei; Zheng, Fang; Zhan, Chang-Guo

    2012-01-01

    It can be argued that an ideal anti-cocaine medication would be one that accelerates cocaine metabolism producing biologically inactive metabolites via a route similar to the primary cocaine-metabolizing pathway, i.e. hydrolysis catalyzed by butyrylcholinesterase (BChE) in plasma. However, wild-type BChE has a low catalytic efficiency against naturally occurring (−)cocaine. Interestingly, wild-type BChE has a much higher catalytic activity against unnatural (+)cocaine. According to available ...

  17. Control of catalytic efficiency by a coevolving network of catalytic and noncatalytic residues

    OpenAIRE

    McMurrough, Thomas A; Dickson, Russell J.; Thibert, Stephanie M. F.; Gloor, Gregory B.; Edgell, David R.

    2014-01-01

    Maximizing structural and functional information from multiple sequence alignments is difficult for protein families that exhibit extreme sequence variation. We addressed this issue by identifying covarying positions within the sequence alignment to predict networks of coevolving amino acid residues in LAGLIDADG homing endonucleases, enzymes used for genome-engineering applications. Intriguingly, the predicted coevolving network with the highest score includes the active-site metal-binding re...

  18. Electro Catalytic Oxidation (ECO) Operation

    Energy Technology Data Exchange (ETDEWEB)

    Morgan Jones

    2011-03-31

    The power industry in the United States is faced with meeting many new regulations to reduce a number of air pollutants including sulfur dioxide, nitrogen oxides, fine particulate matter, and mercury. With over 1,000 power plants in the US, this is a daunting task. In some cases, traditional pollution control technologies such as wet scrubbers and SCRs are not feasible. Powerspan's Electro-Catalytic Oxidation, or ECO{reg_sign} process combines four pollution control devices into a single integrated system that can be installed after a power plant's particulate control device. Besides achieving major reductions in emissions of sulfur dioxide (SO{sub 2}), nitrogen oxides (NOx), fine particulate matter (PM2.5) and mercury (Hg), ECO produces a highly marketable fertilizer, which can help offset the operating costs of the process system. Powerspan has been operating a 50-MW ECO commercial demonstration unit (CDU) at FirstEnergy Corp.'s R.E. Burger Plant near Shadyside, Ohio, since February 2004. In addition to the CDU, a test loop has been constructed beside the CDU to demonstrate higher NOx removal rates and test various scrubber packing types and wet ESP configurations. Furthermore, Powerspan has developed the ECO{reg_sign}{sub 2} technology, a regenerative process that uses a proprietary solvent to capture CO{sub 2} from flue gas. The CO{sub 2} capture takes place after the capture of NOx, SO{sub 2}, mercury, and fine particulate matter. Once the CO{sub 2} is captured, the proprietary solution is regenerated to release CO{sub 2} in a form that is ready for geological storage or beneficial use. Pilot scale testing of ECO{sub 2} began in early 2009 at FirstEnergy's Burger Plant. The ECO{sub 2} pilot unit is designed to process a 1-MW flue gas stream and produce 20 tons of CO{sub 2} per day, achieving a 90% CO{sub 2} capture rate. The ECO{sub 2} pilot program provided the opportunity to confirm process design and cost estimates, and prepare for large

  19. 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...

  20. Ultrasensitive detection of nucleic acids by template enhanced hybridization followed by rolling circle amplification and catalytic hairpin assembly.

    Science.gov (United States)

    Song, Weiling; Zhang, Qiao; Sun, Wenbo

    2015-02-11

    An ultrasensitive protocol for fluorescent detection of DNA is designed by combining the template enhanced hybridization process (TEHP) with Rolling Circle Amplification (RCA) and Catalytic Hairpin Assembly (CHA), showing a remarkable amplification efficiency.

  1. Catalytic destruction of tar in biomass derived producer gas

    International Nuclear Information System (INIS)

    The purpose of this study is to investigate catalytic destruction of tar formed during gasification of biomass, with the goal of improving the quality of the producer gas. This work focuses on nickel based catalysts treated with alkali in an effort to promote steam gasification of the coke that deposits on catalyst surfaces. A tar conversion system consisting of a guard bed and catalytic reactor was designed to treat the producer gas from an air blown, fluidized bed biomass gasifier. The guard bed used dolomite to crack the heavy tars. The catalytic reactor was used to evaluate three commercial steam reforming catalysts. These were the ICI46-1 catalyst from Imperial Chemical Industry and Z409 and RZ409 catalysts from Qilu Petrochemical Corp. in China. A 0.5-3 l/min slipstream from a 5 tpd biomass gasifier was used to test the tar conversion system. Gas and tar were sampled before and after the tar conversion system to evaluate the effectiveness of the system. Changes in gas composition as functions of catalytic bed temperature, space velocity and steam/TOC (total organic carbon) ratio are presented. Structural changes in the catalysts during the tests are also described

  2. Catalytic Radical Reduction in Aqueous Solution by a Ruthenium Hydride Intermediate.

    Science.gov (United States)

    Htet, Yamin; Tennyson, Andrew G

    2016-07-18

    Some manganese complexes can catalyze both antioxidant and pro-oxidant reactions, whereby the disparate reactivity modes are determined by the catalyst environment and afford distinct therapeutic effects. We recently reported the reduction of radicals in buffered aqueous solution catalyzed by a ruthenium complex with biologically relevant non-tertiary alcohols as terminal reductants. Mechanistic evidence is presented, indicating that this catalytic radical reduction is achieved by a Ru-hydride intermediate formed by β-hydride elimination from a Ru-alkoxide species. A similar mechanism and Ru-hydride intermediate was previously reported to kill cancer cells with catalytic pro-oxidant effects. Therefore, our demonstration of catalytic antioxidant effects by the same type of intermediate reveals new potential therapeutic strategies and applications for catalytic systems that form Ru-hydride intermediates. PMID:27254303

  3. Selenium utilization in thioredoxin and catalytic advantage provided by selenocysteine

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Moon-Jung [Department of Biochemistry and Molecular Biology, Yeungnam University College of Medicine, Daegu 705-717 (Korea, Republic of); Lee, Byung Cheon [Division of Genetics, Department of Medicine, Brigham and Women' s Hospital, Harvard Medical School, Boston, MA 02115 (United States); Division of Biotechnology, College of Life Sciences & Biotechnology, Korea University, Seoul 136-701 (Korea, Republic of); Hwang, Kwang Yeon [Division of Biotechnology, College of Life Sciences & Biotechnology, Korea University, Seoul 136-701 (Korea, Republic of); Gladyshev, Vadim N. [Division of Genetics, Department of Medicine, Brigham and Women' s Hospital, Harvard Medical School, Boston, MA 02115 (United States); Kim, Hwa-Young, E-mail: hykim@ynu.ac.kr [Department of Biochemistry and Molecular Biology, Yeungnam University College of Medicine, Daegu 705-717 (Korea, Republic of)

    2015-06-12

    Thioredoxin (Trx) is a major thiol-disulfide reductase that plays a role in many biological processes, including DNA replication and redox signaling. Although selenocysteine (Sec)-containing Trxs have been identified in certain bacteria, their enzymatic properties have not been characterized. In this study, we expressed a selenoprotein Trx from Treponema denticola, an oral spirochete, in Escherichia coli and characterized this selenoenzyme and its natural cysteine (Cys) homologue using E. coli Trx1 as a positive control. {sup 75}Se metabolic labeling and mutation analyses showed that the SECIS (Sec insertion sequence) of T. denticola selenoprotein Trx is functional in the E. coli Sec insertion system with specific selenium incorporation into the Sec residue. The selenoprotein Trx exhibited approximately 10-fold higher catalytic activity than the Sec-to-Cys version and natural Cys homologue and E. coli Trx1, suggesting that Sec confers higher catalytic activity on this thiol-disulfide reductase. Kinetic analysis also showed that the selenoprotein Trx had a 30-fold higher K{sub m} than Cys-containing homologues, suggesting that this selenoenzyme is adapted to work efficiently with high concentrations of substrate. Collectively, the results of this study support the hypothesis that selenium utilization in oxidoreductase systems is primarily due to the catalytic advantage provided by the rare amino acid, Sec. - Highlights: • The first characterization of a selenoprotein Trx is presented. • The selenoenzyme Trx exhibits 10-fold higher catalytic activity than Cys homologues. • Se utilization in Trx is primarily due to the catalytic advantage provided by Sec residue.

  4. Increased biomass yield of Lactococcus lactis by reduced overconsumption of amino acids and increased catalytic activities of enzymes.

    Directory of Open Access Journals (Sweden)

    Kaarel Adamberg

    Full Text Available Steady state cultivation and multidimensional data analysis (metabolic fluxes, absolute proteome, and transcriptome are used to identify parameters that control the increase in biomass yield of Lactococcus lactis from 0.10 to 0.12 C-mol C-mol(-1 with an increase in specific growth rate by 5 times from 0.1 to 0.5 h(-1. Reorganization of amino acid consumption was expressed by the inactivation of the arginine deiminase pathway at a specific growth rate of 0.35 h(-1 followed by reduced over-consumption of pyruvate directed amino acids (asparagine, serine, threonine, alanine and cysteine until almost all consumed amino acids were used only for protein synthesis at maximal specific growth rate. This balanced growth was characterized by a high glycolytic flux carrying up to 87% of the carbon flow and only amino acids that relate to nucleotide synthesis (glutamine, serine and asparagine were consumed in higher amounts than required for cellular protein synthesis. Changes in the proteome were minor (mainly increase in the translation apparatus. Instead, the apparent catalytic activities of enzymes and ribosomes increased by 3.5 times (0.1 vs 0.5 h(-1. The apparent catalytic activities of glycolytic enzymes and ribosomal proteins were seen to follow this regulation pattern while those of enzymes involved in nucleotide metabolism increased more than the specific growth rate (over 5.5 times. Nucleotide synthesis formed the most abundant biomonomer synthetic pathway in the cells with an expenditure of 6% from the total ATP required for biosynthesis. Due to the increase in apparent catalytic activity, ribosome translation was more efficient at higher growth rates as evidenced by a decrease of protein to mRNA ratios. All these effects resulted in a 30% decrease of calculated ATP spilling (0.1 vs 0.5 h(-1. Our results show that bioprocesses can be made more efficient (using a balanced metabolism by varying the growth conditions.

  5. Atmospheric methanol measurement using selective catalytic methanol to formaldehyde conversion

    Directory of Open Access Journals (Sweden)

    S. J. Solomon

    2005-05-01

    Full Text Available A novel atmospheric methanol measurement technique, employing selective gas-phase catalytic conversion of methanol to formaldehyde followed by detection of the formaldehyde product, has been developed and tested. The effects of temperature, gas flow rate, gas composition, reactor-bed length, and reactor-bed composition on the methanol conversion efficiency of a molybdenum-rich, iron-molybdate catalyst [Mo-Fe-O] were studied. Best results were achieved using a 1:4 mixture (w/w of the catalyst in quartz sand. Optimal methanol to formaldehyde conversion (>95% efficiency occurred at a catalyst housing temperature of 345°C and an estimated sample-air/catalyst contact time of <0.2 s. Potential interferences arising from conversion of methane and a number of common volatile organic compounds (VOC to formaldehyde were found to be negligible under most atmospheric conditions and catalyst housing temperatures. Using the new technique, atmospheric measurements of methanol were made at the University of Bremen campus from 1 to 15 July 2004. Methanol mixing ratios ranged from 1 to 5 ppb with distinct maxima at night. Formaldehyde mixing ratios, obtained in conjunction with methanol by periodically bypassing the catalytic converter, ranged from 0.2 to 1.6 ppb with maxima during midday. These results suggest that selective, catalytic methanol to formaldehyde conversion, coupled with existing formaldehyde measurement instrumentation, is an inexpensive and effective means for monitoring atmospheric methanol.

  6. Atmospheric methanol measurement using selective catalytic methanol to formaldehyde conversion

    Directory of Open Access Journals (Sweden)

    S. J. Solomon

    2005-01-01

    Full Text Available A novel atmospheric methanol measurement technique, employing selective gas-phase catalytic conversion of methanol to formaldehyde followed by detection of the formaldehyde product, has been developed and tested. The effects of temperature, gas flow rate, gas composition, reactor-bed length, and reactor-bed composition on the methanol conversion efficiency of a molybdenum-rich, iron-molybdate catalyst [Mo-Fe-O] were studied. Best results were achieved using a 1:4 mixture (w/w of the catalyst in quartz sand. Optimal methanol to formaldehyde conversion (>95% efficiency occurred at a catalyst housing temperature of 345°C and an estimated sample-air/catalyst contact time of <0.2 seconds. Potential interferences arising from conversion of methane and a number of common volatile organic compounds (VOC to formaldehyde were found to be negligible under most atmospheric conditions and catalyst housing temperatures. Using the new technique, atmospheric measurements of methanol were made at the University of Bremen campus from 1 to 15 July 2004. Methanol mixing ratios ranged from 1 to 5 ppb with distinct maxima at night. Formaldehyde mixing ratios, obtained in conjunction with methanol by periodically bypassing the catalytic converter, ranged from 0.2 to 1.6 ppb with maxima during midday. These results suggest that selective, catalytic methanol to formaldehyde conversion, coupled with existing formaldehyde measurement instrumentation, is an inexpensive and effective means for monitoring atmospheric methanol.

  7. Kinetics of heterogeneous catalytic reactions

    CERN Document Server

    Boudart, Michel

    2014-01-01

    This book is a critical account of the principles of the kinetics of heterogeneous catalytic reactions in the light of recent developments in surface science and catalysis science. Originally published in 1984. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These paperback editions preserve the original texts of these important books while presenting them in durable paperback editions. The goal of the Princeton Legacy Library is to vastly increase acc

  8. Molecular catalytic coal liquid conversion

    Energy Technology Data Exchange (ETDEWEB)

    Stock, L.M.; Yang, Shiyong [Univ. of Chicago, IL (United States)

    1995-12-31

    This research, which is relevant to the development of new catalytic systems for the improvement of the quality of coal liquids by the addition of dihydrogen, is divided into two tasks. Task 1 centers on the activation of dihydrogen by molecular basic reagents such as hydroxide ion to convert it into a reactive adduct (OH{center_dot}H{sub 2}){sup {minus}} that can reduce organic molecules. Such species should be robust withstanding severe conditions and chemical poisons. Task 2 is focused on an entirely different approach that exploits molecular catalysts, derived from organometallic compounds that are capable of reducing monocyclic aromatic compounds under very mild conditions. Accomplishments and conclusions are discussed.

  9. Computational Introduction of Catalytic Activity into Proteins.

    Science.gov (United States)

    Bertolani, Steve J; Carlin, Dylan Alexander; Siegel, Justin B

    2016-01-01

    Recently, there have been several successful cases of introducing catalytic activity into proteins. One method that has been used successfully to achieve this is the theozyme placement and enzyme design algorithms implemented in Rosetta Molecular Modeling Suite. Here, we illustrate how to use this software to recapitulate the placement of catalytic residues and ligand into a protein using a theozyme, protein scaffold, and catalytic constraints as input. PMID:27094294

  10. Estimating the temperature of a catalytic converter

    Energy Technology Data Exchange (ETDEWEB)

    Ma, T.T.-H.

    1994-11-02

    A method of estimating the temperature of a catalytic converter used in the exhaust system of an internal combustion engine is described. Heated exhaust gas oxygen (HEGO) sensors are placed upstream and downstream of the catalytic converter. The temperature of the catalytic converter shortly after start-up is measured by monitoring the resistance of the HEGO sensor's heating element. The downstream sensor is used for mixture control and to double check results of the upstream sensor. (UK)

  11. CATALYTIC BEHAVIOR OF SILICA-SUPPORTED POLY-γ-AMINOPROPYL-SILOXANE-Co-Ru BIMETALLIC COMPLEX FOR THE HYDROFORMYLATION OF CYCLOHEXENE

    Institute of Scientific and Technical Information of China (English)

    GUAN Shiyou; HUANG Meiyu; JIANG Yingyan

    1993-01-01

    The cobalt and ruthenium bimetallic complex of poly-γ-amino-propylsiloxane(abbr.as Si-CH2-Co-Ru) was prepared,and it was found that it can catalyze the hydroformylation of cyclohexene effectively with the conversion amounting to over 90%.Cyclohexanecarboxaldehyde was first formed in the hydrofor mylation,and then further hydrogenated to form cylcohexanemethanol.The coversion was affected obviously by the Co/Ru ratio.When Co/Ru molar ratio was 100-150,i.e.in the very low content of noble metal Ru,the catalytic activity of Si-NH2-Co-Ru was also very high.The product composition was affected by CO/H2 ratio in the reaction gas.Aldehyde can be got high selectively by controlling CO/H2 ratio.Compared with other catalyst system,the Si-NH2-Co-Ru catalyst has higher catalytic activity and efficiency with very low Ru/Co ratio.The total turnover number was more than 28,800(based on the amount of ruthenium used).

  12. Perspective on Catalytic Hydrodeoxygenation of Biomass Pyrolysis Oils: Essential Roles of Fe-based Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Yongchun; Hensley, Alyssa; McEwen, Jean-Sabin; Wang, Yong

    2016-06-27

    Catalytic fast pyrolysis is the most promising approach for biofuel production, due to its simple process and versatility to handle lignocellulosic biomass feedstocks with varying and complex compositions. Compared with in situ catalytic fast pyrolysis, ex situ catalytic pyrolysis has the flexibility of optimizing the pyrolysis step and catalytic process individually to improve the quality of pyrolysis oil (stability, oxygen content, acid number, etc.) and to maximize the carbon efficiency in the conversion of biomass to pyrolysis oil. Hydrodeoxygenation is one of the key catalytic functions in ex situ catalytic fast pyrolysis. Recently, Fe-based catalysts have been reported to exhibit superior catalytic properties in hydrodeoxygenation of model compounds in pyrolysis oil, which potentially makes the ex situ pyrolysis of biomass commercially viable due to the abundance and low cost of Fe. Here, we briefly summarize the recent progress on Fe-based catalysts for hydrodeoxygenation of biomass, and provide perspectives on how to further improve Fe-based catalysts (activity and stability) for their potential applications in the emerging area of biomass conversion.

  13. Nanostructured Catalytic Reactors for Air Purification Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I project proposes the development of lightweight compact nanostructured catalytic reactors for air purification from toxic gaseous organic...

  14. Nanostructured Catalytic Reactors for Air Purification Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase II project proposes the development of lightweight compact nanostructured catalytic reactors for air purification from toxic gaseous organic...

  15. Atomic-scale investigations of the struct. and dynamics of complex catalytic materials

    Energy Technology Data Exchange (ETDEWEB)

    Karl Sohlberg, Drexel University

    2007-05-16

    By some accounts, catalysis impacts ≥ 30% of GDP in developed countries [Maxwell, I. E. Nature 394, 325-326 (1998)]. Catalysis is the enabling technology for petroleum production, for control of gaseous emissions from petroleum combustion, and for the production of industrial and consumer chemicals. Future applications of catalysis are potentially even more far reaching. There is an ever-growing need to move the economy from a fossil-fuel energy base to cleaner alternatives. Hydrogen-based combustion systems and fuel cells could play a dominant role, given a plentiful and inexpensive source of hydrogen. Photocatalysis is the most promising clean technology for hydrogen production, relying solely on water and sunlight, but performance enhancements in photocatalysis are needed to make this technology economically competitive. Given the enormously wide spread utilization of catalysts, even incremental performance enhancements would have far-reaching benefits for multiple end-use sectors. In the area of fuel and chemical production, such improvements would translate into vast reductions in energy consumption. At the consumption end, improvements in the catalysts involved would yield tremendous reductions in pollution. In the area of photocatalysis, such efficiency improvements could finally render hydrogen an economically viable fuel. Prerequisite to the non-empirical design and refinement of improved catalysts is the identification of the atomic-scale structure and properties of the catalytically active sites. This has become a major industrial research priority. The focus of this research program was to combine atomic-resolution Z-contrast electron microscopy with first-principles density functional theory calculations to deliver an atomic-scale description of heterogeneous catalytic systems that could form the basis for non-empirical design of improved catalysts with greater energy efficiency.

  16. Catalytic applications in the production of biodiesel from vegetable oils.

    Science.gov (United States)

    Sivasamy, Arumugam; Cheah, Kien Yoo; Fornasiero, Paolo; Kemausuor, Francis; Zinoviev, Sergey; Miertus, Stanislav

    2009-01-01

    The predicted shortage of fossil fuels and related environmental concerns have recently attracted significant attention to scientific and technological issues concerning the conversion of biomass into fuels. First-generation biodiesel, obtained from vegetable oils and animal fats by transesterification, relies on commercial technology and rich scientific background, though continuous progress in this field offers opportunities for improvement. This review focuses on new catalytic systems for the transesterification of oils to the corresponding ethyl/methyl esters of fatty acids. It also addresses some innovative/emerging technologies for the production of biodiesel, such as the catalytic hydrocracking of vegetable oils to hydrocarbons. The special role of the catalyst as a key to efficient technology is outlined, together with the other important factors that affect the yield and quality of the product, including feedstock-related properties and various system conditions. PMID:19360707

  17. Catalytic reforming feed characterisation technique

    Energy Technology Data Exchange (ETDEWEB)

    Larraz Mora, R.; Arvelo Alvarez, R. [Univ. of La Laguna, Chemical Engineering Dept., La Laguna (Spain)

    2002-09-01

    The catalytic reforming of naphtha is one of the major refinery processes, designed to increase the octane number of naphtha or to produce aromatics. The naphtha used as catalytic reformer feedstock usually contains a mixture of paraffins, naphthenes, and aromatics in the carbon number range C{sub 6} to C{sub 10}. The detailed chemical composition of the feed is necessary to predict the aromatics and hydrogen production as well as the operation severity. The analysis of feed naphtha is usually reported in terms of its ASTM distillation curve and API or specific gravity. Since reforming reactions are described in terms of lumped chemical species (paraffins, naphthenes and aromatics), a feed characterisation technique should be useful in order to predict reforming operating conditions and detect feed quality changes. Unfortunately online analyzer applications as cromatography or recently introduced naphtha NMR [1] are scarce in most of refineries. This work proposes an algorithmic characterisation method focusing on its main steps description. The method could help on the subjects previously described, finally a calculation example is shown. (orig.)

  18. MnO2/CeO2 for catalytic ultrasonic degradation of methyl orange.

    Science.gov (United States)

    Zhao, He; Zhang, Guangming; Zhang, Quanling

    2014-05-01

    Catalytic ultrasonic degradation of aqueous methyl orange was studied in this paper. Heterogeneous catalyst MnO2/CeO2 was prepared by impregnation of manganese oxide on cerium oxide. Morphology and specific surface area of MnO2/CeO2 catalyst were characterized and its composition was determined. Results showed big differences between fresh and used catalyst. The removal efficiency of methyl orange by MnO2/CeO2 catalytic ultrasonic process was investigated. Results showed that ultrasonic process could remove 3.5% of methyl orange while catalytic ultrasonic process could remove 85% of methyl orange in 10 min. The effects of free radical scavengers were studied to determine the role of hydroxyl free radical in catalytic ultrasonic process. Results showed that methyl orange degradation efficiency declined after adding free radical scavengers, illustrating that hydroxyl free radical played an important role in degrading methyl orange. Theoretic analysis showed that the resonance size of cavitation bubbles was comparable with the size of catalyst particles. Thus, catalyst particles might act as cavitation nucleus and enhance ultrasonic cavitation effects. Measurement of H2O2 concentration in catalytic ultrasonic process confirmed this hypothesis. Effects of pre-adsorption on catalytic ultrasonic process were examined. Pre-adsorption significantly improved methyl orange removal. The potential explanation was that methyl orange molecules adsorbed on catalysts could enter cavitation bubbles and undergo stronger cavitation. PMID:24369902

  19. Removal of Xylene fromWaste Air Stream Using Catalytic Ozonation Process

    Directory of Open Access Journals (Sweden)

    H Mokarami

    2010-10-01

    Full Text Available "n "n "nBackgrounds and Objectives: Volatile organic compounds (VOCs are one of the common groups of contaminants encountered in the industrial activities, emitted through air stream into the atmosphere. To prevent the human and environmental health from the adverse effects of VOCs, air streams containing VOCs need to be treated before discharging to environment. This study was aimed at investigating the catalytic ozonation process for removing xylene from a contaminated air stream."nMaterials and Methods: In the present work, a bench scale experimental setup was constructed and used for catalytic ozonation of xylene. The performance of catalytic ozonation process was compared with that of single adsorption and ozonation in removal of several concentration of xylene under the similar experimental conditions."nResults: The results indicated that the efficiency of catalytic ozonation was higher than that of single adsorption and ozonation in removal of xylene. The emerging time and elimination capacity of xylene for inlet concentration of 300 ppm was 1.4 and 5.8 times of those in adsorption system. The activated carbon acted as catalyst in the presence of ozone and thus attaining the synergistic effect for xylene degradation."nConclusion: catalytic ozonation process is an efficient technique the treatment of air streams containing high concentrations of xylene. The adsorption systems can also be simply retrofitted to catalytic ozonation process and thereby improving their performance for treating VOCs.

  20. Catalytic Combustion for Ultra-Low NOx Hydrogen Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Etemad, Shahrokh; Baird, Benjamin; Alavandi, Sandeep

    2011-06-30

    Precision Combustion, Inc., (PCI) in close collaboration with Solar Turbines, Incorporated, has developed and demonstrated a combustion system for hydrogen fueled turbines that reduces NOx to low single digit level while maintaining or improving current levels of efficiency and eliminating emissions of carbon dioxide. Full scale Rich Catalytic Hydrogen (RCH1) injector was developed and successfully tested at Solar Turbines, Incorporated high pressure test facility demonstrating low single digit NOx emissions for hydrogen fuel in the range of 2200F-2750F. This development work was based on initial subscale development for faster turnaround and reduced cost. Subscale testing provided promising results for 42% and 52% H2 with NOx emissions of less than 2 ppm with improved flame stability. In addition, catalytic reactor element testing for substrate oxidation, thermal cyclic injector testing to simulate start-stop operation in a gas turbine environment, and steady state 15 atm. operation testing were performed successfully. The testing demonstrated stable and robust catalytic element component life for gas turbine conditions. The benefit of the catalytic hydrogen combustor technology includes capability of delivering near-zero NOx without costly post-combustion controls and without requirement for added sulfur control. In addition, reduced acoustics increase gas turbine component life. These advantages advances Department of Energy (DOE’s) objectives for achievement of low single digit NOx emissions, improvement in efficiency vs. postcombustion controls, fuel flexibility, a significant net reduction in Integrated Gasification Combined Cycle (IGCC) system net capital and operating costs, and a route to commercialization across the power generation field from micro turbines to industrial and utility turbines.

  1. [Catalytic ozonation of nitrobenzene in water by acidification-activated red mud].

    Science.gov (United States)

    Kang, Ya-ning; Li, Hua-nan; Xu, Bing-bing; Qi, Fei; Zhao, Lun

    2013-05-01

    Red mud as one kind of aluminum industrial wastes was used as raw material for catalyst preparation. It was activated by acidification in order to enhance its catalytic activity in the system of catalytic ozonation. Furthermore, removal performance and reaction mechanism in degradation of organic pollutants were discussed. Results showed that acid modified red mud had more significant catalytic activity than the raw red mud. The removal efficiency of nitrobenzene by catalytic ozonation with acidified red mud (RM6.0) increased with the increasing ozone concentration. When the ozone concentration was increased from 0.4 mg x L(-1) to 1.7 mg x L(-1), the removal efficiency of nitrobenzene increased from 45% to 92%. There was a consistent effect of water pH on the removal efficiency and the ozone concentration variation. The variation of the removal efficiency depended on the initial water pH. This was because the concentration of OH(-) led to ozone decomposition to generate hydroxyl radicals. The higher water pH value led to the quenching of hydroxyl radicals, resulting in the reduction of catalytic activity of RM6.0. The experimental results of aqueous ozone concentration variation in the presence of RM6.0 and inhibition by hydroxyl radicals indicated that the main reaction mechanism was catalytic ozonation of NB. Firstly, aqueous ozone was absorbed onto the surface of RM6.0, and then the concentrated ozone oxidized NB in water which was with a combination of direct and indirect oxidation. In catalytic reaction, hydroxyl radicals were present, which were generated during the oxidation of NB on the surface of RM6.0.

  2. Activity prediction of substrates in NADH-dependent carbonyl reductase by docking requires catalytic constraints and charge parameterization of catalytic zinc environment.

    Science.gov (United States)

    Dhoke, Gaurao V; Loderer, Christoph; Davari, Mehdi D; Ansorge-Schumacher, Marion; Schwaneberg, Ulrich; Bocola, Marco

    2015-11-01

    Molecular docking of substrates is more challenging compared to inhibitors as the reaction mechanism has to be considered. This becomes more pronounced for zinc-dependent enzymes since the coordination state of the catalytic zinc ion is of greater importance. In order to develop a predictive substrate docking protocol, we have performed molecular docking studies of diketone substrates using the catalytic state of carbonyl reductase 2 from Candida parapsilosis (CPCR2). Different docking protocols using two docking methods (AutoDock Vina and AutoDock4.2) with two different sets of atomic charges (AM1-BCC and HF-RESP) for catalytic zinc environment and substrates as well as two sets of vdW parameters for zinc ion were examined. We have selected the catalytic binding pose of each substrate by applying mechanism based distance criteria. To compare the performance of the docking protocols, the correlation plots for the binding energies of these catalytic poses were obtained against experimental Vmax values of the 11 diketone substrates for CPCR2. The best correlation of 0.73 was achieved with AutoDock4.2 while treating catalytic zinc ion in optimized non-bonded (NBopt) state with +1.01 charge on the zinc ion, compared to 0.36 in non-bonded (+2.00 charge on the zinc ion) state. These results indicate the importance of catalytic constraints and charge parameterization of catalytic zinc environment for the prediction of substrate activity in zinc-dependent enzymes by molecular docking. The developed predictive docking protocol described here is in principle generally applicable for the efficient in silico substrate spectra characterization of zinc-dependent ADH.

  3. Catalytic hydrocarbon reactions over supported metal oxides. Progress report, April 1, 1994--January 31, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Ekerdt, J.G.

    1995-01-31

    Oxide catalysis plays a central role in hydrocarbon processing and improvements in catalytic activity or selectivity are of great technological importance because these improvements will translate directly into more efficient utilization of hydrocarbon supplies and lower energy consumption in separation processes. An understanding of the relationships between surface structure and catalytic properties is needed to describe and improve oxide catalysts. Our approach has been to prepare supported oxides that have a specific structure and oxidation state and then employ these structures in reaction studies. Our current research program is focused on studying the fundamental relationships between structure and reactivity for two important reactions that are present in many oxide-catalyzed processes, partial oxidation and carbon-carbon bond formation. Oxide catalysis can be a complex process with both metal cation and oxygen anions participating in the chemical reactions. From an energy perspective carbon-carbon bond formation is particularly relevant to CO hydrogenation in isosynthesis. Hydrogenolysis and hydrogenation form the basis for heteroatom removal in fuels processing. Understanding the catalysis of these processes (and others) requires isolating reaction steps in the overall cycle and determining how structure and composition influence the individual reaction steps. Specially designed oxides, such as we use, permit one to study some of the steps in oxidation, carbon-carbon coupling and heteroatom removal catalysis. During the course of our studies we have: (1) developed methods to form and stabilize various Mo and W oxide structures on silica; (2) studied C-H abstraction reactions over the fully oxidized cations; (3) studied C-C bond coupling by methathesis and reductive coupling of aldehydes and ketones over reduced cation structures; and (4) initiated a study of hydrogenation and hydrogenolysis over reduced cation structures.

  4. A Methionine Residue Promotes Hyperoxidation of the Catalytic Cysteine of Mouse Methionine Sulfoxide Reductase A.

    Science.gov (United States)

    Kim, Geumsoo; Levine, Rodney L

    2016-06-28

    Methionine sulfoxide reductase A (msrA) reduces methionine sulfoxide in proteins back to methionine. Its catalytic cysteine (Cys72-SH) has a low pKa that facilitates oxidation by methionine sulfoxide to cysteine sulfenic acid. If the catalytic cycle proceeds efficiently, the sulfenic acid is reduced back to cysteine at the expense of thioredoxin. However, the sulfenic acid is vulnerable to "irreversible" oxidation to cysteine sulfinic acid that inactivates msrA (hyperoxidation). We observed that human msrA is resistant to hyperoxidation while mouse msrA is readily hyperoxidized by micromolar concentrations of hydrogen peroxide. We investigated the basis of this difference in susceptibility to hyperoxidation and established that it is controlled by the presence or absence of a Met residue in the carboxyl-terminal domain of the enzyme, Met229. This residue is Val in human msrA, and when it was mutated to Met, human msrA became sensitive to hyperoxidation. Conversely, mouse msrA was rendered insensitive to hyperoxidation when Met229 was mutated to Val or one of five other residues. Positioning of the methionine at residue 229 is not critical, as hyperoxidation occurred as long as the methionine was located within the group of 14 carboxyl-terminal residues. The carboxyl domain of msrA is known to be flexible and to have access to the active site, and Met residues are known to form stable, noncovalent bonds with aromatic residues through interaction of the sulfur atom with the aromatic ring. We propose that Met229 forms such a bond with Trp74 at the active site, preventing formation of a protective sulfenylamide with Cys72 sulfenic acid. As a consequence, the sulfenic acid is available for facile, irreversible oxidation to cysteine sulfinic acid. PMID:27259041

  5. Catalytic hot gas cleaning of gasification gas

    Energy Technology Data Exchange (ETDEWEB)

    Simell, P. [VTT Energy, Espoo (Finland). Energy Production Technologies

    1997-12-31

    The aim of this work was to study the catalytic cleaning of gasification gas from tars and ammonia. In addition, factors influencing catalytic activity in industrial applications were studied, as well as the effects of different operation conditions and limits. Also the catalytic reactions of tar and ammonia with gasification gas components were studied. The activities of different catalyst materials were measured with laboratory-scale reactors fed by slip streams taken from updraft and fluid bed gasifiers. Carbonate rocks and nickel catalysts proved to be active tar decomposing catalysts. Ammonia decomposition was in turn facilitated by nickel catalysts and iron materials like iron sinter and iron dolomite. Temperatures over 850 deg C were required at 2000{sup -1} space velocity at ambient pressure to achieve almost complete conversions. During catalytic reactions H{sub 2} and CO were formed and H{sub 2}O was consumed in addition to decomposing hydrocarbons and ammonia. Equilibrium gas composition was almost achieved with nickel catalysts at 900 deg C. No deactivation by H{sub 2}S or carbon took place in these conditions. Catalyst blocking by particulates was avoided by using a monolith type of catalyst. The apparent first order kinetic parameters were determined for the most active materials. The activities of dolomite, nickel catalyst and reference materials were measured in different gas atmospheres using laboratory apparatus. This consisted of nitrogen carrier, toluene as tar model compound, ammonia and one of the components H{sub 2}, H{sub 2}O, CO, CO{sub 2}, CO{sub 2}+H{sub 2}O or CO+CO{sub 2}. Also synthetic gasification gas was used. With the dolomite and nickel catalyst the highest toluene decomposition rates were measured with CO{sub 2} and H{sub 2}O. In gasification gas, however, the rate was retarded due to inhibition by reaction products (CO, H{sub 2}, CO{sub 2}). Tar decomposition over dolomite was modelled by benzene reactions with CO{sub 2}, H

  6. (Gold core) at (ceria shell) nanostructures for plasmon-enhanced catalytic reactions under visible light

    KAUST Repository

    Wang, Jianfang

    2014-08-26

    Driving catalytic reactions with sunlight is an excellent example of sustainable chemistry. A prerequisite of solar-driven catalytic reactions is the development of photocatalysts with high solar-harvesting efficiencies and catalytic activities. Herein, we describe a general approach for uniformly coating ceria on monometallic and bimetallic nanocrystals through heterogeneous nucleation and growth. The method allows for control of the shape, size, and type of the metal core as well as the thickness of the ceria shell. The plasmon shifts of the Au@CeO2 nanostructures resulting from the switching between Ce(IV) and Ce(III) are observed. The selective oxidation of benzyl alcohol to benzaldehyde, one of the fundamental reactions for organic synthesis, performed under both broad-band and monochromatic light, demonstrates the visible-light-driven catalytic activity and reveals the synergistic effect on the enhanced catalysis of the Au@CeO2 nanostructures. © 2014 American Chemical Society.

  7. Industrial Gas Turbine Engine Catalytic Pilot Combustor-Prototype Testing

    Energy Technology Data Exchange (ETDEWEB)

    Etemad, Shahrokh [Precision Combustion, Inc., North Haven, CT (United States); Baird, Benjamin [Precision Combustion, Inc., North Haven, CT (United States); Alavandi, Sandeep [Precision Combustion, Inc., North Haven, CT (United States); Pfefferle, William [Precision Combustion, Inc., North Haven, CT (United States)

    2010-04-01

    PCI has developed and demonstrated its Rich Catalytic Lean-burn (RCL®) technology for industrial and utility gas turbines to meet DOE's goals of low single digit emissions. The technology offers stable combustion with extended turndown allowing ultra-low emissions without the cost of exhaust after-treatment and further increasing overall efficiency (avoidance of after-treatment losses). The objective of the work was to develop and demonstrate emission benefits of the catalytic technology to meet strict emissions regulations. Two different applications of the RCL® concept were demonstrated: RCL® catalytic pilot and Full RCL®. The RCL® catalytic pilot was designed to replace the existing pilot (a typical source of high NOx production) in the existing Dry Low NOx (DLN) injector, providing benefit of catalytic combustion while minimizing engine modification. This report discusses the development and single injector and engine testing of a set of T70 injectors equipped with RCL® pilots for natural gas applications. The overall (catalytic pilot plus main injector) program NOx target of less than 5 ppm (corrected to 15% oxygen) was achieved in the T70 engine for the complete set of conditions with engine CO emissions less than 10 ppm. Combustor acoustics were low (at or below 0.1 psi RMS) during testing. The RCL® catalytic pilot supported engine startup and shutdown process without major modification of existing engine controls. During high pressure testing, the catalytic pilot showed no incidence of flashback or autoignition while operating over a wide range of flame temperatures. In applications where lower NOx production is required (i.e. less than 3 ppm), in parallel, a Full RCL® combustor was developed that replaces the existing DLN injector providing potential for maximum emissions reduction. This concept was tested at industrial gas turbine conditions in a Solar Turbines, Incorporated high-pressure (17 atm.) combustion rig and in a modified Solar

  8. Innovative Catalysis in Organic Synthesis Oxidation, Hydrogenation, and C-X Bond Forming Reactions

    CERN Document Server

    Andersson, Pher G

    2012-01-01

    Authored by a European team of leaders in the field, this book compiles innovative approaches for C-X bond forming processes frequently applied in organic synthesis. It covers all key types of catalysis, including homogeneous, heterogeneous, and organocatalysis, as well as mechanistic and computational studies. Special attention is focused on the improvement of efficiency and sustainability of important catalytic processes, such as selective oxidations, hydrogenation and cross-coupling reactions.The result is a valuable resource for both advanced researchers in academia and industry, as well a

  9. Process design for wastewater treatment: catalytic ozonation of organic pollutants.

    Science.gov (United States)

    Derrouiche, S; Bourdin, D; Roche, P; Houssais, B; Machinal, C; Coste, M; Restivo, J; Orfão, J J M; Pereira, M F R; Marco, Y; Garcia-Bordeje, E

    2013-01-01

    Emerging micropollutants have been recently the target of interest for their potential harmful effects in the environment and their resistance to conventional water treatments. Catalytic ozonation is an advanced oxidation process consisting of the formation of highly reactive radicals from the decomposition of ozone promoted by a catalyst. Nanocarbon materials have been shown to be effective catalysts for this process, either in powder form or grown on the surface of a monolithic structure. In this work, carbon nanofibers grown on the surface of a cordierite honeycomb monolith are tested as catalyst for the ozonation of five selected micropollutants: atrazine (ATZ), bezafibrate, erythromycin, metolachlor, and nonylphenol. The process is tested both in laboratorial and real conditions. Later on, ATZ was selected as a target pollutant to further investigate the role of the catalytic material. It is shown that the inclusion of a catalyst improves the mineralization degree compared to single ozonation. PMID:24056437

  10. Catalytic conversion of alcohols to hydrocarbons with low benzene content

    Energy Technology Data Exchange (ETDEWEB)

    Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin

    2016-09-06

    A method for converting an alcohol to a hydrocarbon fraction having a lowered benzene content, the method comprising: converting said alcohol to a hydrocarbon fraction by contacting said alcohol, under conditions suitable for converting said alcohol to said hydrocarbon fraction, with a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon fraction, and contacting said hydrocarbon fraction with a benzene alkylation catalyst, under conditions suitable for alkylating benzene, to form alkylated benzene product in said hydrocarbon fraction. Also described is a catalyst composition useful in the method, comprising a mixture of (i) a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon, and (ii) a benzene alkylation catalyst, in which (i) and (ii) may be in a mixed or separated state. A reactor for housing the catalyst and conducting the reaction is also described.

  11. Crystallography captures catalytic steps in human methionine adenosyltransferase enzymes.

    Science.gov (United States)

    Murray, Ben; Antonyuk, Svetlana V; Marina, Alberto; Lu, Shelly C; Mato, Jose M; Hasnain, S Samar; Rojas, Adriana L

    2016-02-23

    The principal methyl donor of the cell, S-adenosylmethionine (SAMe), is produced by the highly conserved family of methionine adenosyltranferases (MATs) via an ATP-driven process. These enzymes play an important role in the preservation of life, and their dysregulation has been tightly linked to liver and colon cancers. We present crystal structures of human MATα2 containing various bound ligands, providing a "structural movie" of the catalytic steps. High- to atomic-resolution structures reveal the structural elements of the enzyme involved in utilization of the substrates methionine and adenosine and in formation of the product SAMe. MAT enzymes are also able to produce S-adenosylethionine (SAE) from substrate ethionine. Ethionine, an S-ethyl analog of the amino acid methionine, is known to induce steatosis and pancreatitis. We show that SAE occupies the active site in a manner similar to SAMe, confirming that ethionine also uses the same catalytic site to form the product SAE.

  12. Catalytic conversion of alcohols to hydrocarbons with low benzene content

    Energy Technology Data Exchange (ETDEWEB)

    Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin

    2016-03-08

    A method for converting an alcohol to a hydrocarbon fraction having a lowered benzene content, the method comprising: converting said alcohol to a hydrocarbon fraction by contacting said alcohol, under conditions suitable for converting said alcohol to said hydrocarbon fraction, with a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon fraction, and contacting said hydrocarbon fraction with a benzene alkylation catalyst, under conditions suitable for alkylating benzene, to form alkylated benzene product in said hydrocarbon fraction. Also described is a catalyst composition useful in the method, comprising a mixture of (i) a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon, and (ii) a benzene alkylation catalyst, in which (i) and (ii) may be in a mixed or separated state. A reactor for housing the catalyst and conducting the reaction is also described.

  13. Acoustics of automotive catalytic converter assemblies

    Science.gov (United States)

    Dickey, Nolan S.; Selamet, Ahmet; Parks, Steve J.; Tallio, Kevin V.; Miazgowicz, Keith D.; Radavich, Paul M.

    2003-10-01

    In an automotive exhaust system, the purpose of the catalytic converter is to reduce pollutant emissions. However, catalytic converters also affect the engine and exhaust system breathing characteristics; they increase backpressure, affect exhaust system acoustic characteristics, and contribute to exhaust manifold tuning. Thus, radiated sound models should include catalytic converters since they can affect both the source characteristics and the exhaust system acoustic behavior. A typical catalytic converter assembly employs a ceramic substrate to carry the catalytically active noble metals. The substrate has numerous parallel tubes and is mounted in a housing with swelling mat or wire mesh around its periphery. Seals at the ends of the substrate can be used to help force flow through the substrate and/or protect the mat material. Typically, catalytic converter studies only consider sound propagation in the small capillary tubes of the substrate. Investigations of the acoustic characteristics of entire catalytic converter assemblies (housing, substrate, seals, and mat) do not appear to be available. This work experimentally investigates the acoustic behavior of catalytic converter assemblies and the contributions of the separate components to sound attenuation. Experimental findings are interpreted with respect to available techniques for modeling sound propagation in ceramic substrates.

  14. Understanding catalytic biomass conversion through data mining

    NARCIS (Netherlands)

    E.J. Ras; B. McKay; G. Rothenberg

    2010-01-01

    Catalytic conversion of biomass is a key challenge that we chemists face in the twenty-first century. Worldwide, research is conducted into obtaining bulk chemicals, polymers and fuels. Our project centres on glucose valorisation via furfural derivatives using catalytic hydrogenation. We present her

  15. A temperature window for the synthesis of single-walled carbon nanotubes by catalytic chemical vapor deposition of CH4 over Mo-Fe/MgO catalyst

    Institute of Scientific and Technical Information of China (English)

    OUYANG Yu; CHEN LI; LIU Qi-xin; FANG Yan

    2008-01-01

    A temperature window of single-walled carbon nanotubes(SWCNTs)growth has been studied by Raman spectroscopy.The results presented when temperature lowcr than 750℃,there were few SWCNTs formed,and when temperature higher than 900℃,mass amorphous carbons were formed in the SWCNTs bundles due to the serf-decomposition of CH4.The temperature window of SWCNTs efficiently growth is between 800 and 900℃,and the optimum growth temperature is about 850℃.These results were supported by transmission electron microscope images of samples formed under different temperature.The temperature window is important for large-scale production of SWCNTs by catalytic chemical vapor deposition method.

  16. Catalytic glycerol steam reforming for hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Dan, Monica, E-mail: monica.dan@itim-cj.ro; Mihet, Maria, E-mail: maria.mihet@itim-cj.ro; Lazar, Mihaela D., E-mail: diana.lazar@itim-cj.ro [National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, 400293 Cluj Napoca (Romania)

    2015-12-23

    Hydrogen production from glycerol by steam reforming combine two major advantages: (i) using glycerol as raw material add value to this by product of bio-diesel production which is obtained in large quantities around the world and have a very limited utilization now, and (ii) by implication of water molecules in the reaction the efficiency of hydrogen generation is increased as each mol of glycerol produces 7 mol of H{sub 2}. In this work we present the results obtained in the process of steam reforming of glycerol on Ni/Al{sub 2}O{sub 3}. The catalyst was prepared by wet impregnation method and characterized through different methods: N{sub 2} adsorption-desorption, XRD, TPR. The catalytic study was performed in a stainless steel tubular reactor at atmospheric pressure by varying the reaction conditions: steam/carbon ratio (1-9), gas flow (35 ml/min -133 ml/min), temperature (450-650°C). The gaseous fraction of the reaction products contain: H{sub 2}, CH{sub 4}, CO, CO{sub 2}. The optimum reaction conditions as resulted from this study are: temperature 550°C, Gly:H{sub 2}O ratio 9:1 and Ar flow 133 ml/min. In these conditions the glycerol conversion to gaseous products was 43% and the hydrogen yield was 30%.

  17. Catalytic glycerol steam reforming for hydrogen production

    Science.gov (United States)

    Dan, Monica; Mihet, Maria; Lazar, Mihaela D.

    2015-12-01

    Hydrogen production from glycerol by steam reforming combine two major advantages: (i) using glycerol as raw material add value to this by product of bio-diesel production which is obtained in large quantities around the world and have a very limited utilization now, and (ii) by implication of water molecules in the reaction the efficiency of hydrogen generation is increased as each mol of glycerol produces 7 mol of H2. In this work we present the results obtained in the process of steam reforming of glycerol on Ni/Al2O3. The catalyst was prepared by wet impregnation method and characterized through different methods: N2 adsorption-desorption, XRD, TPR. The catalytic study was performed in a stainless steel tubular reactor at atmospheric pressure by varying the reaction conditions: steam/carbon ratio (1-9), gas flow (35 ml/min -133 ml/min), temperature (450-650°C). The gaseous fraction of the reaction products contain: H2, CH4, CO, CO2. The optimum reaction conditions as resulted from this study are: temperature 550°C, Gly:H2O ratio 9:1 and Ar flow 133 ml/min. In these conditions the glycerol conversion to gaseous products was 43% and the hydrogen yield was 30%.

  18. Microchannel Reactor System for Catalytic Hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Adeniyi Lawal; Woo Lee; Ron Besser; Donald Kientzler; Luke Achenie

    2010-12-22

    We successfully demonstrated a novel process intensification concept enabled by the development of microchannel reactors, for energy efficient catalytic hydrogenation reactions at moderate temperature, and pressure, and low solvent levels. We designed, fabricated, evaluated, and optimized a laboratory-scale microchannel reactor system for hydrogenation of onitroanisole and a proprietary BMS molecule. In the second phase of the program, as a prelude to full-scale commercialization, we designed and developed a fully-automated skid-mounted multichannel microreactor pilot plant system for multiphase reactions. The system is capable of processing 1 – 10 kg/h of liquid substrate, and an industrially relevant immiscible liquid-liquid was successfully demonstrated on the system. Our microreactor-based pilot plant is one-of-akind. We anticipate that this process intensification concept, if successfully demonstrated, will provide a paradigm-changing basis for replacing existing energy inefficient, cost ineffective, environmentally detrimental slurry semi-batch reactor-based manufacturing practiced in the pharmaceutical and fine chemicals industries.

  19. Reducing catalytic converter pressure loss

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-06-01

    This article examines why approximately 30--40% of total exhaust-system pressure loss occurs in the catalytic converter and what can be done to reduce pressure loss. High exhaust-system backpressure is of concern in the design of power trains for passenger cars and trucks because it penalizes fuel economy and limits peak power. Pressure losses occur due to fluid shear and turning during turbulent flow in the converter headers and in entry separation and developing laminar-flow boundary layers within the substrate flow passages. Some of the loss mechanisms are coupled. For example, losses in the inlet header are influenced by the presence of the flow resistance of a downstream substrate. Conversely, the flow maldistribution and pressure loss of the substrate(s) depend on the design of the inlet header.

  20. Non-catalytic recuperative reformer

    Energy Technology Data Exchange (ETDEWEB)

    Khinkis, Mark J.; Kozlov, Aleksandr P.; Kurek, Harry

    2015-12-22

    A non-catalytic recuperative reformer has a flue gas flow path for conducting hot flue gas from a thermal process and a reforming mixture flow path for conducting a reforming mixture. At least a portion of the reforming mixture flow path is embedded in the flue gas flow path to permit heat transfer from the hot flue gas to the reforming mixture. The reforming mixture flow path contains substantially no material commonly used as a catalyst for reforming hydrocarbon fuel (e.g., nickel oxide, platinum group elements or rhenium), but instead the reforming mixture is reformed into a higher calorific fuel via reactions due to the heat transfer and residence time. In a preferred embodiment, extended surfaces of metal material such as stainless steel or metal alloy that are high in nickel content are included within at least a portion of the reforming mixture flow path.

  1. Catalytic Graphitization of Phenolic Resin

    Institute of Scientific and Technical Information of China (English)

    Mu Zhao; Huaihe Song

    2011-01-01

    The catalytic graphitization of thermal plastic phenolic-formaldehyde resin with the aid of ferric nitrate (FN) was studied in detail. The morphologies and structural features of the products including onion-like carbon nanoparticles and bamboo-shaped carbon nanotubes were investigated by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction and Raman spectroscopy measurements. It was found that with the changes of loading content of FN and residence time at 1000℃, the products exhibited various morphologies. The TEM images showed that bamboo-shaped carbon nanotube consisted of tens of bamboo sticks and onion-like carbon nanoparticle was made up of quasi-spherically concentrically closed carbon nanocages.

  2. Efficient Synthesis of Optically Active Alcohols

    Institute of Scientific and Technical Information of China (English)

    J.S. Chen; Z.R. Dong; Y.Y. Li; B.Z. Li; Y. Xing; W.Y. Shen; G. Chen; X.Q. Zhang; J. X. Gao

    2005-01-01

    @@ 1Introduction Optically active secondary alcohols are versatile building blocks for synthesis of unnatural biological active compounds and functional materials. Therefore, study on efficient synthesis of optically active alcohols is becoming an important subject in synthetic organic chemistry. Catalytic asymmetric reduction of carbonyl compounds is a practical method to create chiral alcohols. For the past decades, a large number of catalytic methods have been developed to achieve this goal.

  3. Catalytic converter with thermoelectric generator

    Energy Technology Data Exchange (ETDEWEB)

    Parise, R.J.

    1998-07-01

    The unique design of an electrically heated catalyst (EHC) and the inclusion of an ECO valve in the exhaust of an internal combustion engine will meet the strict new emission requirements, especially at vehicle cold start, adopted by several states in this country as well as in Europe and Japan. The catalytic converter (CC) has been a most useful tool in pollution abatement for the automobile. But the emission requirements are becoming more stringent and, along with other improvements, the CC must be improved to meet these new standards. Coupled with the ECO valve, the EHC can meet these new emission limits. In an internal combustion engine vehicle (ICEV), approximately 80% of the energy consumed leaves the vehicle as waste heat: out the tail pipe, through the radiator, or convected/radiated off the engine. Included with the waste heat out the tail pipe are the products of combustion which must meet strict emission requirements. The design of a new CC is presented here. This is an automobile CC that has the capability of producing electrical power and reducing the quantity of emissions at vehicle cold start, the Thermoelectric Catalytic Power Generator. The CC utilizes the energy of the exothermic reactions that take place in the catalysis substrate to produce electrical energy with a thermoelectric generator. On vehicle cold start, the thermoelectric generator is used as a heat pump to heat the catalyst substrate to reduce the time to catalyst light-off. Thus an electrically heated catalyst (EHC) will be used to augment the abatement of tail pipe emissions. Included with the EHC in the exhaust stream of the automobile is the ECO valve. This valve restricts the flow of pollutants out the tail pipe of the vehicle for a specified amount of time until the EHC comes up to operating temperature. Then the ECO valve opens and allows the full exhaust, now treated by the EHC, to leave the vehicle.

  4. Selective Catalytic Synthesis Using the Combination of Carbon Dioxide and Hydrogen: Catalytic Chess at the Interface of Energy and Chemistry.

    Science.gov (United States)

    Klankermayer, Jürgen; Wesselbaum, Sebastian; Beydoun, Kassem; Leitner, Walter

    2016-06-20

    The present Review highlights the challenges and opportunities when using the combination CO2 /H2 as a C1 synthon in catalytic reactions and processes. The transformations are classified according to the reduction level and the bond-forming processes, covering the value chain from high volume basic chemicals to complex molecules, including biologically active substances. Whereas some of these concepts can facilitate the transition of the energy system by harvesting renewable energy into chemical products, others provide options to reduce the environmental impact of chemical production already in today's petrochemical-based industry. Interdisciplinary fundamental research from chemists and chemical engineers can make important contributions to sustainable development at the interface of the energetic and chemical value chain. The present Review invites the reader to enjoy this exciting area of "catalytic chess" and maybe even to start playing some games in her or his laboratory. PMID:27237963

  5. System Study of Rich Catalytic/Lean burn (RCL) Catalytic Combustion for Natural Gas and Coal-Derived Syngas Combustion Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Shahrokh Etemad; Lance Smith; Kevin Burns

    2004-12-01

    Rich Catalytic/Lean burn (RCL{reg_sign}) technology has been successfully developed to provide improvement in Dry Low Emission gas turbine technology for coal derived syngas and natural gas delivering near zero NOx emissions, improved efficiency, extending component lifetime and the ability to have fuel flexibility. The present report shows substantial net cost saving using RCL{reg_sign} technology as compared to other technologies both for new and retrofit applications, thus eliminating the need for Selective Catalytic Reduction (SCR) in combined or simple cycle for Integrated Gasification Combined Cycle (IGCC) and natural gas fired combustion turbines.

  6. Catalytic Polymer Multilayer Shell Motors for Separation of Organics.

    Science.gov (United States)

    Lin, Zhihua; Wu, Zhiguang; Lin, Xiankun; He, Qiang

    2016-01-26

    A catalytic polymer multilayer shell motor has been developed, which effects fast motion-based separation of charged organics in water. The shell motors are fabricated by sputtering platinum onto the exposed surface of silica templates embedded in Parafilm, followed by layer-by-layer assembly of polyelectrolyte multilayers to the templates. The catalytic shell motors display high bubble propulsion with speeds of up to 260 μm s(-1) (13 body lengths per second). Moreover, the polyelectrolyte multilayers assembled at high pH (pH>9.0) adsorb approximately 89% of dye molecules from water, owing to the electrostatic interaction between the positively charged polymers and the anionic dye molecules, and subsequently release them at neutral pH in a microfluidic device. The efficient propulsion coupled with the effective adsorption behavior of the catalytic shell motors in a microfluidic device results in accelerated separation of organics in water and thus holds considerable promise for water analysis. PMID:26632275

  7. Catalytic extraction processing of contaminated scrap metal

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, T.P.; Johnston, J.E.; Payea, B.M. [Molten Metal Technology, Inc., Waltham, MA (United States)] [and others

    1995-10-01

    The U.S. Department of Energy issued a Planned Research and Development Announcement (PRDA) in 1993, with the objective of identifying unique technologies which could be applied to the most hazardous waste streams at DOE sites. The combination of radioactive contamination with additional contamination by hazardous constituents such as those identified by the Resource Conservation and Recovery Act (RCRA) pose an especially challenging problem. Traditional remediation technologies are increasingly becoming less acceptable to stakeholders and regulators because of the risks they pose to public health and safety. Desirable recycling technologies were described by the DOE as: (1) easily installed, operated, and maintained; (2) exhibiting superior environmental performance; (3) protective of worker and public health and safety; (4) readily acceptable to a wide spectrum of evaluators; and (5) economically feasible. Molten Metal Technology, Inc. (MMT) was awarded a contract as a result of the PRDA initiative to demonstrate the applicability of Catalytic Extraction Processing (CEP), MMT`s proprietary elemental recycling technology, to DOE`s inventory of low level mixed waste. This includes DOE`s inventory of radioactively- and RCRA-contaminated scrap metal and other waste forms expected to be generated by the decontamination and decommissioning (D&D) of DOE sites.

  8. Diesel NO{sub x} catalytic converter development: A review

    Energy Technology Data Exchange (ETDEWEB)

    Heimrich, M.J. [Southwest Research Inst., San Antonio, TX (United States)

    1996-07-01

    This paper summarizes the findings of several technical articles on diesel NO{sub x} catalytic converter technology. Simplified theoretical reactions for NO{sub x} removal are discussed. Currently, development of catalytic NO{sub x} control technology for diesel engines is focused on systems that incorporate fuel hydrocarbons as the chemical reducing agent. Copper- and zeolite-based catalysts have been the predominant systems studied to date, but now catalysts containing precious metals are being investigated. Observed NO{sub x} reduction efficiencies typically ranged from 10 to 30 percent on actual engine exhaust systems when exhaust hydrocarbon enrichment strategies were used. Effects of carbon monoxide, sulfur dioxide, and water on NO{sub x} reduction efficiencies are reviewed. Recommendations for future research include attempts to broaden the temperature range of efficient NO{sub x} reduction, improving hydrocarbon selectivity toward the NO{sub x} reduction reaction, and the development of a supplementary reductant delivery system suitable for transient diesel engine operation.

  9. Catalytic partial oxidation of pyrolysis oils

    Science.gov (United States)

    Rennard, David Carl

    2009-12-01

    details the catalytic partial oxidation of glycerol without preheat: droplets of glycerol are sprayed directly onto the top of the catalyst bed, where they react autothermally with contact times on the order of tau ≈ 30 ms. The reactive flash volatilization of glycerol results in equilibrium syngas production over Rh-Ce catalysts. In addition, water can be added to the liquid glycerol, resulting in true autothermal reforming. This highly efficient process can increase H2 yields and alter the H2 to CO ratio, allowing for flexibility in syngas quality depending on the purpose. Chapter 5 details the results of a time on stream experiment, in which optimal syngas conditions are chosen. Although conversion is 100% for 450 hours, these experiments demonstrate the deactivation of the catalyst over time. Deactivation is exhibited by decreases in H2 and CO 2 production accompanied by a steady increase in CO and temperature. These results are explained as a loss of water-gas shift equilibration. SEM images suggest catalyst sintering may play a role; EDS indicates the presence of impurities on the catalyst. In addition, the instability of quartz in the reactor is demonstrated by etching, resulting in a hole in the reactor tube at the end of the experiment. These results suggest prevaporization may be desirable in this application, and that quartz is not a suitable material for the reactive flash volatilization of oxygenated fuels. In Chapter 6, pyrolysis oil samples from three sources - poplar, pine, and hardwoods - are explored in the context of catalytic partial oxidation. Lessons derived from the tests with model compounds are applied to reactor design, resulting in the reactive flash vaporization of bio oils. Syngas is successfully produced, though deactivation due to coke and ash deposition keeps H2 below equlibrium. Coke formation is observed on the reactor walls, but is avoided between the fuel injection site and catalyst by increasing the proximity of these in the reactor

  10. Electrochemistry of Layered Graphitic Carbon Nitride Synthesised from Various Precursors: Searching for Catalytic Effects.

    Science.gov (United States)

    Yew, Ying Teng; Lim, Chee Shan; Eng, Alex Yong Sheng; Oh, Junghoon; Park, Sungjin; Pumera, Martin

    2016-02-16

    Graphitic carbon nitride (g-C3 N4 ), synthesised by pyrolysis of different precursors (dicyandiamide, melamine and urea) under varying reaction conditions (air and nitrogen gas) is subjected to electrochemical studies for the elucidation of the inherent catalytic efficiency of the pristine material. Contrary to popular belief, pristine g-C3 N4 shows negligible, if any, enhancement in its electrochemical behaviour in this comprehensive study. Voltammetric analysis reveals g-C3 N4 to display similar catalytic efficiency to the unmodified glassy carbon electrode surface on which the bulk material was deposited. This highlights the non-catalytic nature of the pristine material and challenges the feasibility of using g-C3 N4 as a heterogeneous catalyst to deliver numerous promised applications.

  11. Catalytic strategy used by the myosin motor to hydrolyze ATP.

    Science.gov (United States)

    Kiani, Farooq Ahmad; Fischer, Stefan

    2014-07-22

    Myosin is a molecular motor responsible for biological motions such as muscle contraction and intracellular cargo transport, for which it hydrolyzes adenosine 5'-triphosphate (ATP). Early steps of the mechanism by which myosin catalyzes ATP hydrolysis have been investigated, but still missing are the structure of the final ADP·inorganic phosphate (Pi) product and the complete pathway leading to it. Here, a comprehensive description of the catalytic strategy of myosin is formulated, based on combined quantum-classical molecular mechanics calculations. A full exploration of catalytic pathways was performed and a final product structure was found that is consistent with all experiments. Molecular movies of the relevant pathways show the different reorganizations of the H-bond network that lead to the final product, whose γ-phosphate is not in the previously reported HPγO4(2-) state, but in the H2PγO4(-) state. The simulations reveal that the catalytic strategy of myosin employs a three-pronged tactic: (i) Stabilization of the γ-phosphate of ATP in a dissociated metaphosphate (PγO3(-)) state. (ii) Polarization of the attacking water molecule, to abstract a proton from that water. (iii) Formation of multiple proton wires in the active site, for efficient transfer of the abstracted proton to various product precursors. The specific role played in this strategy by each of the three loops enclosing ATP is identified unambiguously. It explains how the precise timing of the ATPase activation during the force generating cycle is achieved in myosin. The catalytic strategy described here for myosin is likely to be very similar in most nucleotide hydrolyzing enzymes.

  12. Low temperature catalytic combustion of natural gas - hydrogen - air mixtures

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-08-01

    The low temperature catalytic combustion of natural gas - air mixtures would allow the development of no-NO{sub x} burners for heating and power applications. Using commercially available catalysts, the room temperature ignition of methane-propane-air mixtures has been shown in laboratory reactors with combustion efficiencies over 95% and maximum temperatures less than 700{sup o}C. After a 500 hour stability test, severe deactivation of both methane and propane oxidation functions was observed. In cooperation with industrial partners, scaleup to 3 kW is being investigated together with startup dynamics and catalyst stability. (author) 3 figs., 3 refs.

  13. Catalytic arylation methods from the academic lab to industrial processes

    CERN Document Server

    Burke, Anthony J

    2014-01-01

    A current view of the challenging field of catalytic arylation reactions. Clearly structured, the chapters in this one-stop resource are arranged according to the reaction type, and focus on novel, efficient and sustainable processes, rather than the well-known and established cross-coupling methods.The entire contents are written by two authors with academic and industrial expertise to ensure consistent coverage of the latest developments in the field, as well as industrial applications, such as C-H activation, iron and gold-catalyzed coupling reactions, cycloadditions or novel methodologies

  14. Catalytic residues Lys197 and Arg199 of Bacillus subtilis phosphoribosyl diphosphate synthase. Alanine-scanning mutagenesis of the flexible catalytic loop

    DEFF Research Database (Denmark)

    Hove-Jensen, Bjarne; Bentsen, Ann-Kristin K; Harlow, Kenneth W

    2005-01-01

    Eleven of the codons specifying the amino acids of the flexible catalytic loop [KRRPRPNVAEVM(197-208)] of Bacillus subtilis phosphoribosyl diphosphate synthase have been changed individually to specify alanine. The resulting variant enzyme forms, as well as the wildtype enzyme, were produced in a...

  15. Effects of different forms of inorganic P on rhizosphere in different P-efficiency wheat%不同形态无机磷对两种磷效率小麦根际特征的影响

    Institute of Scientific and Technical Information of China (English)

    侯焱焱; 展晓莹; 刘璇; 张乃明; 张淑香

    2011-01-01

    以磷高效型小麦小偃54和磷低效型小麦京411为材料的砂培试验,通过测定植株生物量及吸磷量、根系形态特征、根际pH、磷酸酶活性,研究不同形态无机磷WP(KH2PO4),Al-P(AlPO4)和Fe-P(FePO4)对两种磷效率小麦根际特征的影响.结果表明,在WP处理下,两种磷效率小麦的地上部吸磷量、总吸磷量和磷吸收效率均显著高于其它处理,而其根冠比和磷利用效率却低于其他处理.除了根部吸磷量,小偃54的生物量和吸磷量有高于京411的趋势.除了WP处理,其他处理的小偃54的根冠比和地下吸磷量均高于京411.所有处理的小偃54的根长和根体积均显著高于京411,且不施磷条件(PO)下更为明显,小偃54根系长度是京411的1.6倍;此外,小偃54根系磷酸酶活性均比京411弱.除Al-P外,小偃54的根际酸化能力较京411强.由此可见,磷胁迫条件下,磷高效小麦根系形态特征改变是根际磷活化的主要机理之一,且受磷水平、磷形态及其溶解性的影响.%The experiment was conducted to investigate effects of different forms of inorganic P on characteristics of rhizosphere in different P-efficiency wheat under the gravel culture conditions. Two different P-efficient wheat genotypea ( the Peffcient wheat Xiaoyan54 and the P-inefficient wheat Jing411 ) were selected for the study. Crop biomass, P uptake amount, pH and phosphatase activity in the rhizosphere under different forms of inorsanic P were measured. Result showed that: with WP (KH2P04) application, the P adsorption efficency (PAE), the shoot and total of P uptake of the two wheat genotypes were higher than that of other treatments, while reversely root/shoot and P use efficiency (PUE). Besides the P uptake of root, the biomass and p uptake of Xiaoyan54 were higher than those of Jing411. The root/shoot and P uptake of root of Xiaoyan54 was higher than those of Jing411, except the WP treatment. Root length of Xiaoyan54 and root volume for

  16. Optimization of the catalytic converter internal flow by using 3D-CFD; Sanjigen nagare kaiseki ni yoru shokubai converter nai nagare no saitekika

    Energy Technology Data Exchange (ETDEWEB)

    Toi, M.; Sugiura, S. [Toyota Motor Corp., Tokyo (Japan)

    1997-10-01

    By using computational fluid dynamics and statistical quality control method, we investigated the contribution of front and rear catalytic converter cone shape for the pressure loss and the partial flow, also led the optimal terms and the predictional formulations efficiently. According to this, we can investigate the optimal position of the catalytic converter from the planning. 8 figs., 6 tabs.

  17. Study on the adsorptive catalytic voltammetry of aloe-emodin at a carbon paste electrode

    Institute of Scientific and Technical Information of China (English)

    LI; Ju'nan; GAO; Peng; LI; Xiangling; YAN; Zhihong; MAO; Xu

    2005-01-01

    A new catalytic voltammetric method for the determination of anthraqunone medicines at a carbon paste electrode (CPE) was described for the first time. The mechanism of the catalytic reaction was investigated by using linear sweep voltammetry, cyclic voltammetry, constant potential electrolysis and so on. The experiment results indicate that aloe-emodin was efficiently accumulated at a CPE by adsorption. In the following potential scan, aloe-emodin was reduced to homologous anthrahydroquinone compound, then the compound was immediately oxidized to aloe-emodin by the dissolved oxygen, and the aloe-emodin was again reduced at the CPE. As a result, a cyclic catalytic reaction was established. But a reversible redox reaction of aloe-emodin can only be observed at a mercury electrode, no catalytic reaction occurs there. A sensitive catalytic voltammetric peak of aloe-emodin was obtained at about -0.60 V (vs. SCE) in 0.56 mol/L NH3-NH4Cl buffer (pH 8.9). The proposed method was applied to the determination of aloe-emodin in the Radix Rhei with satisfactory results. The determination results were in good agreement with reference values obtained by the HPLC. The adsorptive catalytic voltammetry for the determination of organic compound at CPE, chemically modified electrode and other solid electrodes could be significant in the studies on pharmacology, pharmacodynamics, toxicity of medicine, clinical medicine and biochemistry.

  18. Catalytic Conversion of Cellulose to Levulinic Acid by Metal Chlorides

    Directory of Open Access Journals (Sweden)

    Beixiao Zhang

    2010-08-01

    Full Text Available The catalytic performance of various metal chlorides in the conversion of cellulose to levulinic acid in liquid water at high temperatures was investigated. The effects of reaction parameters on the yield of levulinic acid were also explored. The results showed that alkali and alkaline earth metal chlorides were not effective in conversion of cellulose, while transition metal chlorides, especially CrCl3, FeCl3 and CuCl2 and a group IIIA metal chloride (AlCl3, exhibited high catalytic activity. The catalytic performance was correlated with the acidity of the reaction system due to the addition of the metal chlorides, but more dependent on the type of metal chloride. Among those metal chlorides, chromium chloride was found to be exceptionally effective for the conversion of cellulose to levulinic acid, affording an optimum yield of 67 mol % after a reaction time of 180 min, at 200 °C, with a catalyst dosage of 0.02 M and substrate concentration of 50 wt %. Chromium metal, most of which was present in its oxide form in the solid sample and only a small part in solution as Cr3+ ion, can be easily separated from the resulting product mixture and recycled. Finally, a plausible reaction scheme for the chromium chloride catalyzed conversion of cellulose in water was proposed.

  19. Coupling between catalytic loop motions and enzyme global dynamics.

    Directory of Open Access Journals (Sweden)

    Zeynep Kurkcuoglu

    Full Text Available Catalytic loop motions facilitate substrate recognition and binding in many enzymes. While these motions appear to be highly flexible, their functional significance suggests that structure-encoded preferences may play a role in selecting particular mechanisms of motions. We performed an extensive study on a set of enzymes to assess whether the collective/global dynamics, as predicted by elastic network models (ENMs, facilitates or even defines the local motions undergone by functional loops. Our dataset includes a total of 117 crystal structures for ten enzymes of different sizes and oligomerization states. Each enzyme contains a specific functional/catalytic loop (10-21 residues long that closes over the active site during catalysis. Principal component analysis (PCA of the available crystal structures (including apo and ligand-bound forms for each enzyme revealed the dominant conformational changes taking place in these loops upon substrate binding. These experimentally observed loop reconfigurations are shown to be predominantly driven by energetically favored modes of motion intrinsically accessible to the enzyme in the absence of its substrate. The analysis suggests that robust global modes cooperatively defined by the overall enzyme architecture also entail local components that assist in suitable opening/closure of the catalytic loop over the active site.

  20. Catalytic reaction in confined flow channel

    Energy Technology Data Exchange (ETDEWEB)

    Van Hassel, Bart A.

    2016-03-29

    A chemical reactor comprises a flow channel, a source, and a destination. The flow channel is configured to house at least one catalytic reaction converting at least a portion of a first nanofluid entering the channel into a second nanofluid exiting the channel. The flow channel includes at least one turbulating flow channel element disposed axially along at least a portion of the flow channel. A plurality of catalytic nanoparticles is dispersed in the first nanofluid and configured to catalytically react the at least one first chemical reactant into the at least one second chemical reaction product in the flow channel.

  1. Removal of ammonia from producer gas in biomass gasification: integration of gasification optimisation and hot catalytic gas cleaning

    Energy Technology Data Exchange (ETDEWEB)

    Hongrapipat, Janjira; Saw, Woei-Lean; Pang, Shusheng [University of Canterbury, Department of Chemical and Process Engineering, Christchurch (New Zealand)

    2012-12-15

    Ammonia (NH{sub 3}) is one of the main contaminants in the biomass gasification producer gas, which is undesirable in downstream applications, and thus must be removed. When the producer gas is used in integrated gasification combined cycle (IGCC) technology, NH{sub 3} is the main precursor of nitrogen oxides (NO{sub x}) formed in gas turbine, whereas in Fischer-Tropsch synthesis and in integrated gasification fuel cell (IGFC) technology, the NH{sub 3} gas poisons the catalysts employed. This paper presents a critical review on the recent development in the understanding of the NH{sub 3} formation in biomass gasification process and in the NH{sub 3} gas cleaning technologies. The NH{sub 3} gas concentration in the producer gas can firstly be reduced by the primary measures taken in the gasification process by operation optimisation and using in-bed catalytic materials. Further removal of the NH{sub 3} gas can be implemented by the secondary measures introduced in the post-gasification gas-cleaning process. Focus is given on the catalytic gas cleaning in the secondary measures and its advantages are analysed including energy efficiency, impacts on environment and recyclability of the catalyst. Based on the review, the most effective cleaning process is proposed with integration of both the primary and the secondary measures for application in a biomass gasification process. (orig.)

  2. Integrated Process for the Catalytic Conversion of Biomass-Derived Syngas into Transportation Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Lebarbier, Vanessa M.; Smith, Colin D.; Flake, Matthew D.; Albrecht, Karl O.; Gray, Michel J.; Ramasamy, Karthikeyan K.; Dagle, Robert A.

    2016-04-19

    Efficient synthesis of renewable fuels that will enable cost competitiveness with petroleum-derived fuels remains a grand challenge for U.S. scientists. In this paper, we report on an integrated catalytic approach for producing transportation fuels from biomass-derived syngas. The composition of the resulting hydrocarbon fuel can be modulated to meet specified requirements. Biomass-derived syngas is first converted over an Rh-based catalyst into a complex aqueous mixture of condensable C2+ oxygenated compounds (predominantly ethanol, acetic acid, acetaldehyde, ethyl acetate). This multi-component aqueous mixture then is fed to a second reactor loaded with a ZnxZryOz mixed oxide catalyst, which has tailored acid-base sites, to produce an olefin mixture rich in isobutene. The olefins then are oligomerized using a solid acid catalyst (e.g., Amberlyst-36) to form condensable olefins with molecular weights that can be targeted for gasoline, jet, and/or diesel fuel applications. The product rich in long-chain olefins (C7+) is finally sent to a fourth reactor that is needed for hydrogenation of the olefins into paraffin fuels. Simulated distillation of the hydrotreated oligomerized liquid product indicates that ~75% of the hydrocarbons present are in the jet-fuel range. Process optimization for the oligomerization step could further improve yield to the jet-fuel range. All of these catalytic steps have been demonstrated in sequence, thus providing proof-of-concept for a new integrated process for the production of drop-in biofuels. This unique and flexible process does not require external hydrogen and also could be applied to non-syngas derived feedstock, such as fermentation products (e.g., ethanol, acetic acid, etc.), other oxygenates, and mixtures thereof containing alcohols, acids, aldehydes and/or esters.

  3. Bottom-Up Catalytic Approach towards Nitrogen-Enriched Mesoporous Carbons/Sulfur Composites for Superior Li-S Cathodes

    OpenAIRE

    Fugen Sun; Jitong Wang; Huichao Chen; Wenming Qiao; Licheng Ling; Donghui Long

    2013-01-01

    We demonstrate a sustainable and efficient approach to produce high performance sulfur/carbon composite cathodes via a bottom-up catalytic approach. The selective oxidation of H2S by a nitrogen-enriched mesoporous carbon catalyst can produce elemental sulfur as a by-product which in-situ deposit onto the carbon framework. Due to the metal-free catalytic characteristic and high catalytic selectivity, the resulting sulfur/carbon composites have almost no impurities that thus can be used as cath...

  4. Vacuum-insulated catalytic converter

    Energy Technology Data Exchange (ETDEWEB)

    Benson, David K. (Golden, CO)

    2001-01-01

    A catalytic converter has an inner canister that contains catalyst-coated substrates and an outer canister that encloses an annular, variable vacuum insulation chamber surrounding the inner canister. An annular tank containing phase-change material for heat storage and release is positioned in the variable vacuum insulation chamber a distance spaced part from the inner canister. A reversible hydrogen getter in the variable vacuum insulation chamber, preferably on a surface of the heat storage tank, releases hydrogen into the variable vacuum insulation chamber to conduct heat when the phase-change material is hot and absorbs the hydrogen to limit heat transfer to radiation when the phase-change material is cool. A porous zeolite trap in the inner canister absorbs and retains hydrocarbons from the exhaust gases when the catalyst-coated substrates and zeolite trap are cold and releases the hydrocarbons for reaction on the catalyst-coated substrate when the zeolite trap and catalyst-coated substrate get hot.

  5. TiO2-sludge carbon enhanced catalytic oxidative reaction in environmental wastewaters applications.

    Science.gov (United States)

    Athalathil, Sunil; Erjavec, Boštjan; Kaplan, Renata; Stüber, Frank; Bengoa, Christophe; Font, Josep; Fortuny, Agusti; Pintar, Albin; Fabregat, Azael

    2015-12-30

    The enhanced oxidative potential of sludge carbon/TiO2 nano composites (SNCs), applied as heterogeneous catalysts in advanced oxidation processes (AOPs), was studied. Fabrification of efficient SNCs using different methods and successful evaluation of their catalytic oxidative activity is reported for the first time. Surface modification processes of hydrothermal deposition, chemical treatment and sol-gel solution resulted in improved catalytic activity and good surface chemistry of the SNCs. The solids obtained after chemical treatment and hydrothermal deposition processes exhibit excellent crystallinity and photocatalytic activity. The highest photocatalytic rate was obtained for the material prepared using hydrothermal deposition technique, compared to other nanocomposites. Further, improved removal of bisphenol A (BPA) from aqueous phase by means of catalytic ozonation and catalytic wet air oxidation processes is achieved over the solid synthesized using chemical treatment method. The present results demonstrate that the addition of TiO2 on the surface of sludge carbon (SC) increases catalytic oxidative activity of SNCs. The latter produced from harmful sludge materials can be therefore used as cost-effective and efficient sludge derived catalysts for the removal of hazardous pollutants. PMID:26223014

  6. Oxidative cracking of n-Hexane : a catalytic pathway to olefins

    NARCIS (Netherlands)

    Boyadjian, Cassia

    2010-01-01

    Steam cracking, the major, current existing route for light olefin production, is the most energy consuming process in the chemical industry. The need for an energy efficient processes, urged substantial research work for the development of new catalytic technologies for light olefin production. Ste

  7. One-Pot Catalytic Conversion of Cellulose and of Woody Biomass Solids to Liquid Fuels

    NARCIS (Netherlands)

    Matson, Theodore D.; Barta, Katalin; Iretskii, Alexei V.; Ford, Peter C.

    2011-01-01

    Efficient methodologies for converting biomass solids to liquid fuels have the potential to reduce dependence on imported petroleum while easing the atmospheric carbon dioxide burden. Here, we report quantitative catalytic conversions of wood and cellulosic solids to liquid and gaseous products in a

  8. Novel catalytic effects of Mn3O4 for all vanadium redox flow batteries.

    Science.gov (United States)

    Kim, Ki Jae; Park, Min-Sik; Kim, Jae-Hun; Hwang, Uk; Lee, Nam Jin; Jeong, Goojin; Kim, Young-Jun

    2012-06-01

    A new approach for enhancing the electrochemical performance of carbon felt electrodes by employing non-precious metal oxides is designed. The outstanding electro-catalytic activity and mechanical stability of Mn(3)O(4) are advantageous in facilitating the redox reaction of vanadium ions, leading to efficient operation of a vanadium redox flow battery. PMID:22540132

  9. The generation of electricity by gas turbines using the catalytic combustion of low-Btu gases

    DEFF Research Database (Denmark)

    Frederiksen, O.P.; Qvale, Einar Bjørn

    1989-01-01

    Various systems for the generation of electricity by gas turbines using catalytic combustion of low-Btu gases have been investigated. Parametric studies of three configurations that are deemed to be practically feasible have been completed. It is shown that thermodynamic efficiency of these systems...

  10. Novel catalytic effects of Mn3O4 for all vanadium redox flow batteries.

    Science.gov (United States)

    Kim, Ki Jae; Park, Min-Sik; Kim, Jae-Hun; Hwang, Uk; Lee, Nam Jin; Jeong, Goojin; Kim, Young-Jun

    2012-06-01

    A new approach for enhancing the electrochemical performance of carbon felt electrodes by employing non-precious metal oxides is designed. The outstanding electro-catalytic activity and mechanical stability of Mn(3)O(4) are advantageous in facilitating the redox reaction of vanadium ions, leading to efficient operation of a vanadium redox flow battery.

  11. Removal of Disinfection By-Products from Contaminated Water Using a Synthetic Goethite Catalyst via Catalytic Ozonation and a Biofiltration System

    Directory of Open Access Journals (Sweden)

    Yu-Hsiang Wang

    2014-09-01

    Full Text Available The effects of synthetic goethite (α-FeOOH used as the catalyst in catalytic ozonation for the degradation of disinfection by-product (DBP precursors are investigated. A biofiltration column applied following the catalytic ozonation process is used to evaluate the efficiency of removing DBP precursors via biotreatment. Ozone can rapidly react with aromatic compounds and oxidize organic compounds, resulting in a decrease in the fluorescence intensity of dissolved organic matter (DOM. In addition, catalytic ozonation can break down large organic molecules, which causes a blue shift in the emission-excitation matrix spectra. Water treated with catalytic ozonation is composed of low-molecular structures, including soluble microbial products (SMPs and other aromatic proteins (APs. The DOM in SMPs and APs is removed by subsequent biofiltration. Catalytic ozonation has a higher removal efficiency for dissolved organic carbon and higher ultraviolet absorbance at 254 nm compared to those of ozonation without a catalyst. The use of catalytic ozonation and subsequent biofiltration leads to a lower DBP formation potential during chlorination compared to that obtained using ozonation and catalytic ozonation alone. Regarding DBP species during chlorination, the bromine incorporation factor (BIF of trihalomethanes and haloacetic acids increases with increasing catalyst dosage in catalytic ozonation. Moreover, the highest BIF is obtained for catalytic ozonation and subsequent biofiltration.

  12. Catalytic models developed through social work

    DEFF Research Database (Denmark)

    Jensen, Mogens

    2015-01-01

    The article develops the concept of catalytic processes in relation to social work with adolescents in an attempt to both reach a more nuanced understanding of social work and at the same time to develop the concept of catalytic processes in psychology. The social work is pedagogical treatment...... of adolescents placed in out-of-home care and is characterised using three situated cases as empirical data. Afterwards the concept of catalytic processes is briefly presented and then applied in an analysis of pedagogical treatment in the three cases. The result is a different conceptualisation of the social...... work with new possibilities of development of the work, but also suggestions for development of the concept of catalytic processes....

  13. Catalytic oxidation of CS2 over atmospheric particles and oxide catalysts

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The catalytic oxidization of CS2 over atmospheric particles and some oxide catalysts was explored through FT-IR, MS and a fixed-bed stainless steel reactor. The results show that at mospheric particles and some oxide catalysts exhibited considerable oxidizing activities for CS2 at ambient temperature. The reaction products are mainly COS and elemental sulfur, even CO2 on some catalysts. Among the catalysts, CaO has the strongest catalytic activity for oxidizing CS2. Fe2O3 is weaker than CaO. The catalytic activity for AI2O3 reduces considerably compared with the former two catalysts, and SiO2 the weakest. Atmospheric particle samples' catalytic activity is be tween Fe2O3's and AI2O3's. The atmospheric particle sample collected mainly consists of Ca(AI2Si2O8)· 4H2O, which is also the main component of cement. COS, the main product, is formed by the catalytic oxidization of CS2 with adsorbed “molecular” oxygen over the catalysts' surfaces. The concentration of adsorbed oxygen over catalysts' surfaces may be the key factor contributed to the oxidizing activity. It is indicated that CS2 could be catalytically oxidized over at mospheric particles, which induced that this reaction may be another important source of atmos pheric COS from CS2.

  14. Dimerization interface of 3-hydroxyacyl-CoA dehydrogenase tunes the formation of its catalytic intermediate.

    Directory of Open Access Journals (Sweden)

    Yingzhi Xu

    Full Text Available 3-Hydroxyacyl-CoA dehydrogenase (HAD, EC 1.1.1.35 is a homodimeric enzyme localized in the mitochondrial matrix, which catalyzes the third step in fatty acid β-oxidation. The crystal structures of human HAD and subsequent complexes with cofactor/substrate enabled better understanding of HAD catalytic mechanism. However, numerous human diseases were found related to mutations at HAD dimerization interface that is away from the catalytic pocket. The role of HAD dimerization in its catalytic activity needs to be elucidated. Here, we solved the crystal structure of Caenorhabditis elegans HAD (cHAD that is highly conserved to human HAD. Even though the cHAD mutants (R204A, Y209A and R204A/Y209A with attenuated interactions on the dimerization interface still maintain a dimerization form, their enzymatic activities significantly decrease compared to that of the wild type. Such reduced activities are in consistency with the reduced ratios of the catalytic intermediate formation. Further molecular dynamics simulations results reveal that the alteration of the dimerization interface will increase the fluctuation of a distal region (a.a. 60-80 that plays an important role in the substrate binding. The increased fluctuation decreases the stability of the catalytic intermediate formation, and therefore the enzymatic activity is attenuated. Our study reveals the molecular mechanism about the essential role of the HAD dimerization interface in its catalytic activity via allosteric effects.

  15. Effects of Dealumination and Desilication of Beta Zeolite on Catalytic Performance in n-Hexane Cracking

    Directory of Open Access Journals (Sweden)

    Yong Wang

    2016-01-01

    Full Text Available Catalytic cracking of n-hexane to selectively produce propylene on Beta zeolite was carried out. The H-Beta (HB (Si/Al = 77 zeolite showed higher catalytic stability and propylene selectivity than the Al-rich HB (Si/Al = 12, due to its smaller number of acid sites, especially Lewis acid sites (LAS. However, catalytic stability and propylene selectivity in high n-hexane conversions were still not satisfactory. After dealumination with HNO3 treatment, catalytic stability was improved and propylene selectivity during high n-hexane conversions was increased. On the other hand, catalytic stability was not improved after desilication with NaOH treatment, although mesopores were formed. This may be related to the partially destroyed structure. However, propylene selectivity in high n-hexane conversions was increased after alkali treatment. We successfully found that the catalytic stability was improved and the propylene selectivity in high n-hexane conversions was further increased after the NaOH treatment followed by HNO3 treatment. This is due to the decrease in the number of acid sites and the increase in mesopores which are beneficial to the diffusion of coke precursor.

  16. Selective catalytic reduction of NOx by hydrocarbons over Fe/ZSM5 prepared by sublimation of FeCl3

    OpenAIRE

    Battiston, A.A.

    2003-01-01

    Selective Catalytic Reduction of NOx by Hydrocarbons over Fe/ZSM5 Prepared by Sublimation of FeCl3. Characterization and Catalysis Nitrogen oxides (NOx) are unwanted by-products of combustion. They are generated primarily from motor vehicles and stationary sources, like power stations and industrial heaters. New catalytic materials are constantly developed in order to improve the efficiency of the cleaning-up technologies for NOx. With this respect an important breakthrough has recently been ...

  17. Thermo-Catalytic Methane Decomposition for Hydrogen Production: Effect of Palladium Promoter on Ni-based Catalysts

    OpenAIRE

    Irene Lock Sow Mei; S.S.M. Lock; Dai-Viet N. Vo; Bawadi Abdullah

    2016-01-01

    Hydrogen production from the direct thermo-catalytic decomposition of methane is a promising alternative for clean fuel production. However, thermal decomposition of methane can hardly be of any practical and empirical interest in the industry unless highly efficient and effective catalysts, in terms of both catalytic activity and operational lifetime have been developed. In this study, the effect of palladium (Pd) as a promoter onto Ni supported on alumina catalyst has been investigated by u...

  18. Investigating the Synthesis, Structure, and Catalytic Properties of Versatile Gold-Based Nanocatalvsts

    Science.gov (United States)

    Pretzer, Lori A.

    Transition metal nanomaterials are used to catalyze many chemical reactions, including those key to environmental, medicinal, and petrochemical fields. Improving their catalytic properties and lifetime would have significant economic and environmental rewards. Potentially expedient options to make such advancements are to alter the shape, size, or composition of transition metal nanocatalysts. This work investigates the relationships between structure and catalytic properties of synthesized Au, Pd-on-Au, and Au-enzyme model transition metal nanocatalysts. Au and Pd-on-Au nanomaterials were studied due to their wide-spread application and structure-dependent electronic and geometric properties. The goal of this thesis is to contribute design procedures and synthesis methods that enable the preparation of more efficient transition metal nanocatalysts. The influence of the size and composition of Pd-on-Au nanoparticles (NPs) was systematically investigated and each was found to affect the catalyst's surface structure and catalytic properties. The catalytic hydrodechlorination of trichloroethene and reduction of 4-nitrophenol by Pd-on-Au nanoparticles were investigated as these reactions are useful for environmental and pharmaceutical synthesis applications, respectively. Structural characterization revealed that the dispersion and oxidation state of surface Pd atoms are controlled by the Au particle size and concentration of Pd. These structural changes are correlated with observed Pd-on-Au NP activities for both probe reactions, providing new insight into the structure-activity relationships of bimetallic nanocatalysts. Using the structure-dependent electronic properties of Au NPs, a new type of light-triggered biocatalyst was prepared and used to remotely control a model biochemical reaction. This biocatalyst consists of a model thermophilic glucokinase enzyme covalently attached to the surface of Au nanorods. The rod-like shape of the Au nanoparticles made the

  19. MOBILE COMPLEX FOR CATALYTIC THERMAL WASTE TREATMENT

    Directory of Open Access Journals (Sweden)

    Vedi V.E.

    2012-12-01

    Full Text Available The design and purpose of the basic units of the mobile waste processing complex “MPK” are described. Experimental data of catalytic purification of exhaust gases are presented. Experimental data on catalytic clearing of final gases of a designed mobile incinerator plant are shown. It is defined, that concentrating of parasitic bridging in waste gases of the complex are considerably smaller, rather than allowed by normative documents.

  20. MOBILE COMPLEX FOR CATALYTIC THERMAL WASTE TREATMENT

    OpenAIRE

    Vedi V.E.; Rovenskii A.I.

    2012-01-01

    The design and purpose of the basic units of the mobile waste processing complex “MPK” are described. Experimental data of catalytic purification of exhaust gases are presented. Experimental data on catalytic clearing of final gases of a designed mobile incinerator plant are shown. It is defined, that concentrating of parasitic bridging in waste gases of the complex are considerably smaller, rather than allowed by normative documents.

  1. Catalytic Radical Domino Reactions in Organic Synthesis

    Science.gov (United States)

    Sebren, Leanne J.; Devery, James J.; Stephenson, Corey R.J.

    2014-01-01

    Catalytic radical-based domino reactions represent important advances in synthetic organic chemistry. Their development benefits synthesis by providing atom- and step-economical methods to complex molecules. Intricate combinations of radical, cationic, anionic, oxidative/reductive, and transition metal mechanistic steps result in cyclizations, additions, fragmentations, ring-expansions, and rearrangements. This Perspective summarizes recent developments in the field of catalytic domino processes. PMID:24587964

  2. Catalytic ammonia oxidation to nitrogen (I) oxide

    OpenAIRE

    MASALITINA NATALIYA YUREVNA; SAVENKOV ANATOLIY SERGEEVICH

    2015-01-01

    The process of synthesis of nitrous oxide by low-temperature catalytical oxidation of NH has been investigated for organic synthesis. The investigation has been carried out by the stage separation approach with NH oxidation occurring in several reaction zones, which characterized by different catalytic conditions. The selectivity for N₂O was 92–92,5 % at the ammonia conversion of 98–99.5 % in the optimal temperature range.

  3. Temperature Modulation of a Catalytic Gas Sensor

    OpenAIRE

    Eike Brauns; Eva Morsbach; Sebastian Kunz; Marcus Baeumer; Walter Lang

    2014-01-01

    The use of catalytic gas sensors usually offers low selectivity, only based on their different sensitivities for various gases due to their different heats of reaction. Furthermore, the identification of the gas present is not possible, which leads to possible misinterpretation of the sensor signals. The use of micro-machined catalytic gas sensors offers great advantages regarding the response time, which allows advanced analysis of the sensor response. By using temperature modulation, additi...

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

    Science.gov (United States)

    Cortright, Randy D.; Dumesic, James A.

    2011-01-18

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

  5. Multiple steady states of fluid catalytic cracking unit with high-efficiency regenerator:effect of reaction temperature control strategy on heat feedback%高效再生催化裂化装置多稳态分析:反应温度开/闭环控制条件对热反馈机制的影响

    Institute of Scientific and Technical Information of China (English)

    王锐; 罗雄麟; 许锋

    2014-01-01

    针对催化裂化反应-再生系统在提升管反应温度开环和闭环控制条件下的输出与输入多稳态问题,分析了烧焦罐式高效再生催化裂化反应-再生系统在两种条件下随着CO助燃剂添加量变化时的多稳态分布。在反应温度开环条件下,因再生温度与反应温度的耦合程度较低,使系统移热曲线呈单调递增,导致了系统出现3个稳态操作点。在反应温度闭环控制条件下,提升管反应器和再生器间热反馈机制发生改变,由于再生剂循环量可以作为额外的自由度对再生温度和反应温度之差进行补偿,再生器和提升管反应器的耦合程度增强,使得系统只会在助燃剂添加量极低时才会出现多个稳态点,而在基准操作条件下只有一个稳态点,规避了系统在提升管反应温度开环时的多个稳态点的问题。%Analyses of multiple steady states of a fluid catalytic cracking unit (FCCU) with high-efficiency regenerator with the riser reaction temperature under open loop and closed loop control were performed based on the theory of output multiplicity and input multiplicity. The multiple steady states under these two conditions were determined with respect to the amount of the added CO combustion promoter. The heat removal curve was found monotonously increasing with riser reaction temperature under open loop control, which resulted in the existence of three multiple steady states because of weak coupling between regenerator temperature and riser reaction temperature. On the other hand, the heat feedback of regenerator and riser reactor changed under closed loop control because regenerated catalyst flow rate could be used as an extra measure to compensate the difference between regenerator temperature and riser reaction temperature to enhance coupling between regerator temperature and riser reactor temperature. Multiple steady states would exist only when CO promoter was extremely

  6. An Experimental Study of Flow and Thermal Transient Response in a Race-Track Monolith Catalytic Converter Etude expérimentale de l'écoulement et de la réponse thermique en régime transitoire dans un pot catalytique muni d'un monolithe de forme ovale

    Directory of Open Access Journals (Sweden)

    Leclerc J. P.

    2006-11-01

    Full Text Available A model for the pressure drop was proposed and compared to experimental results. Global flow characteristics and velocity distribution were studied from residence time distribution measurements in a race-trackmonolith. Significant dead volumes were detected and the velocity distribution was determined. The effect of flow-rate, inlet tube diameter and flow deflector was investigated. Study of the time evolution of outlet temperature and temperature distribution in a monolith coated or not with catalyst makes it possible to determine the thermal characteristics of heat-up. The influence of flow rate, velocity distribution and developing laminar flow regime in the channel were qualitatively estimated. Theses results allow one to determine the hydrodynamic and thermal behavior of the catalytic converter and to propose reliable and realistic assumptions for subsequent modeling. Chaque année, un véhicule de moyenne cylindrée rejette dans l'atmosphère 240 kg de monoxyde de carbone, 40 kg d'oxyde d'azote et 77 kg d'hydrocarbures [1]. Si le moteur propre semble être la meilleure solution pour l'avenir, le pot catalytique est aujourd'hui la seule solution envisageable. Le fonctionnement du pot catalytique est satisfaisant lorsque la voiture roule à une vitesse constante. Cependant, il n'en est pas de même lors du démarrage à froid pendant lequel de nombreux problèmes subsistent, comme le montre la figure 1. Plusieurs modèles ont été développés afin de comprendre et d'améliorer les performances du pot catalytique [2, 3, 11, 12 et 13]. Cependant, suivant les hypothèses faites, ces modèles fournissent des résultats plus ou moins contradictoires. Une étude expérimentale a donc été effectuée afin de mieux cerner les processus qui gouvernent le fonctionnement du pot catalytique et de proposer des hypothèses réalistes pour la modélisation. Un modèle d'estimation de la perte de charge a été proposé et comparé aux résultats exp

  7. Degradation of paracetamol by catalytic wet air oxidation and sequential adsorption - Catalytic wet air oxidation on activated carbons

    Energy Technology Data Exchange (ETDEWEB)

    Quesada-Penate, I. [Universite de Toulouse, INPT, UPS, Laboratoire de Genie Chimique, 4, Allee Emile Monso, F-31432 Toulouse (France); CNRS, Laboratoire de Genie Chimique, F-31432 Toulouse (France); Julcour-Lebigue, C., E-mail: carine.julcour@ensiacet.fr [Universite de Toulouse, INPT, UPS, Laboratoire de Genie Chimique, 4, Allee Emile Monso, F-31432 Toulouse (France); CNRS, Laboratoire de Genie Chimique, F-31432 Toulouse (France); Jauregui-Haza, U.J. [Instituto Superior de Tecnologias y Ciencias Aplicadas, Ave. Salvador Allende y Luaces, Habana (Cuba); Wilhelm, A.M.; Delmas, H. [Universite de Toulouse, INPT, UPS, Laboratoire de Genie Chimique, 4, Allee Emile Monso, F-31432 Toulouse (France); CNRS, Laboratoire de Genie Chimique, F-31432 Toulouse (France)

    2012-06-30

    Highlights: Black-Right-Pointing-Pointer Three activated carbons (AC) compared as adsorbents and oxidation catalysts. Black-Right-Pointing-Pointer Similar evolution for catalytic and adsorptive properties of AC over reuses. Black-Right-Pointing-Pointer Acidic and mesoporous AC to be preferred, despite lower initial efficiency. Black-Right-Pointing-Pointer Oxidative degradation of paracetamol improves biodegradability. Black-Right-Pointing-Pointer Convenient hybrid adsorption-regenerative oxidation process for continuous treatment. - Abstract: The concern about the fate of pharmaceutical products has raised owing to the increasing contamination of rivers, lakes and groundwater. The aim of this paper is to evaluate two different processes for paracetamol removal. The catalytic wet air oxidation (CWAO) of paracetamol on activated carbon was investigated both as a water treatment technique using an autoclave reactor and as a regenerative treatment of the carbon after adsorption in a sequential fixed bed process. Three activated carbons (ACs) from different source materials were used as catalysts: two microporous basic ACs (S23 and C1) and a meso- and micro-porous acidic one (L27). During the first CWAO experiment the adsorption capacity and catalytic performance of fresh S23 and C1 were higher than those of fresh L27 despite its higher surface area. This situation changed after AC reuse, as finally L27 gave the best results after five CWAO cycles. Respirometry tests with activated sludge revealed that in the studied conditions the use of CWAO enhanced the aerobic biodegradability of the effluent. In the ADOX process L27 also showed better oxidation performances and regeneration efficiency. This different ageing was examined through AC physico-chemical properties.

  8. Efficient stereoselective synthesis of 2-acetamido-1,2-dideoxyallonojirimycin (DAJNAc) and sp(2)-iminosugar conjugates: Novel hexosaminidase inhibitors with discrimination capabilities between the mature and precursor forms of the enzyme.

    Science.gov (United States)

    de la Fuente, Alex; Rísquez-Cuadro, Rocío; Verdaguer, Xavier; García Fernández, José M; Nanba, Eiji; Higaki, Katsumi; Ortiz Mellet, Carmen; Riera, Antoni

    2016-10-01

    Due to their capacity to inhibit hexosaminidases, 2-acetamido-1,2-dideoxy-iminosugars have been widely studied as potential therapeutic agents for various diseases. An efficient stereoselective synthesis of 2-acetamido-1,2-dideoxyallonojirimycin (DAJNAc), the most potent inhibitor of human placenta β-N-acetylglucosaminidase (β-hexosaminidase) among the epimeric series, is here described. This novel procedure can be easily scaled up, providing enough material for structural modifications and further biological tests. Thus, two series of sp(2)-iminosugar conjugates derived from DAJNAc have been prepared, namely monocyclic DAJNAc-thioureas and bicyclic 2-iminothiazolidines, and their glycosidase inhibitory activity evaluated. The data evidence the utmost importance of developing diversity-oriented synthetic strategies allowing optimization of electrostatic and hydrophobic interactions to achieve high inhibitory potencies and selectivities among isoenzymes. Notably, strong differences in the inhibition potency of the compounds towards β-hexosaminidase from human placenta (mature) or cultured fibroblasts (precursor form) were encountered. The ensemble of data suggests that the ratio between them, and not the inhibition potency towards the placenta enzyme, is a good indication of the chaperoning potential of TaySachs disease-associated mutant hexosaminidase.

  9. On the Structural Context and Identification of Enzyme Catalytic Residues

    OpenAIRE

    Yu-Tung Chien; Shao-Wei Huang

    2013-01-01

    Enzymes play important roles in most of the biological processes. Although only a small fraction of residues are directly involved in catalytic reactions, these catalytic residues are the most crucial parts in enzymes. The study of the fundamental and unique features of catalytic residues benefits the understanding of enzyme functions and catalytic mechanisms. In this work, we analyze the structural context of catalytic residues based on theoretical and experimental structure flexibility. The...

  10. Co-N Decorated Hierarchically Porous Graphene Aerogel for Efficient Oxygen Reduction Reaction in Acid.

    Science.gov (United States)

    Fu, Xiaogang; Choi, Ja-Yeon; Zamani, Pouyan; Jiang, Gaopeng; Hoque, Md Ariful; Hassan, Fathy Mohamed; Chen, Zhongwei

    2016-03-01

    Nitrogen-functionalized graphene materials have been demonstrated as promising electrocatalyst for the oxygen reduction reaction (ORR), owning to their respectable activity and excellent stability in alkaline electrolyte. However, they exhibit unacceptable catalytic activity in acid medium. Here, a hierarchically porous Co-N functionalized graphene aerogel is prepared as an efficient catalyst for the ORR in acid electrolyte. In the preparation process, polyaniline (PANI) is introduced as a pore-forming agent to aid in the self-assembly of graphene species into a porous aerogel networks, and a nitrogen precursor to induce in situ nitrogen doping. Therefore, a Co-N decorated graphene aerogel framework with a large surface area (485 m(2) g(-1)) and an abundance of meso/macropores is effectively formed after heat treatment. Such highly desired structures can not only expose sufficient active sites for the ORR but also guarantee the fast mass transfer in the catalytic process, which provides significant catalytic activity with positive onset and half wave potentials, low hydrogen peroxide yield, high resistance to methanol crossover, and remarkable stability that is comparable to commercial Pt/C in acid medium.

  11. Co-N Decorated Hierarchically Porous Graphene Aerogel for Efficient Oxygen Reduction Reaction in Acid.

    Science.gov (United States)

    Fu, Xiaogang; Choi, Ja-Yeon; Zamani, Pouyan; Jiang, Gaopeng; Hoque, Md Ariful; Hassan, Fathy Mohamed; Chen, Zhongwei

    2016-03-01

    Nitrogen-functionalized graphene materials have been demonstrated as promising electrocatalyst for the oxygen reduction reaction (ORR), owning to their respectable activity and excellent stability in alkaline electrolyte. However, they exhibit unacceptable catalytic activity in acid medium. Here, a hierarchically porous Co-N functionalized graphene aerogel is prepared as an efficient catalyst for the ORR in acid electrolyte. In the preparation process, polyaniline (PANI) is introduced as a pore-forming agent to aid in the self-assembly of graphene species into a porous aerogel networks, and a nitrogen precursor to induce in situ nitrogen doping. Therefore, a Co-N decorated graphene aerogel framework with a large surface area (485 m(2) g(-1)) and an abundance of meso/macropores is effectively formed after heat treatment. Such highly desired structures can not only expose sufficient active sites for the ORR but also guarantee the fast mass transfer in the catalytic process, which provides significant catalytic activity with positive onset and half wave potentials, low hydrogen peroxide yield, high resistance to methanol crossover, and remarkable stability that is comparable to commercial Pt/C in acid medium. PMID:26937737

  12. Progress in catalytic membrane reactors for removing sulfur from natural gas

    Institute of Scientific and Technical Information of China (English)

    TAO Chang-yuan; LIU Zuo-hua; DU Jun; LIU Ren-long

    2007-01-01

    Increasingly high requirement driven by environmental concern leads to more rigorous standards for sulfur dosage in fuel. Natural gas desulfurization is an important unit for industrial natural gas process. Catalytic membrane reactor for sulfur compounds removal is a newly emerged and integrated membrane technology. We reviewed the current progress for desulfurization of natural gas with membrane process, and predicted that the process combined with catalytic membrane reactor and microwave irradiation for desulfurization of natural gas might be an integrated and promising unit for large scale desulfurization with high efficiency.

  13. Effect of citrate on Aspergillus niger phytase adsorption and catalytic activity in soil

    Science.gov (United States)

    Mezeli, Malika; Menezes-Blackburn, Daniel; Zhang, Hao; Giles, Courtney; George, Timothy; Shand, Charlie; Lumsdon, David; Cooper, Patricia; Wendler, Renate; Brown, Lawrie; Stutter, Marc; Blackwell, Martin; Darch, Tegan; Wearing, Catherine; Haygarth, Philip

    2015-04-01

    Current developments in cropping systems that promote mobilisation of phytate in agricultural soils, by exploiting plant-root exudation of phytase and organic acids, offer potential for developments in sustainable phosphorus use. However, phytase adsorption to soil particles and phytate complexion has been shown to inhibit phytate dephosphorylation, thereby inhibiting plant P uptake, increasing the risk of this pool contributing to diffuse pollution and reducing the potential benefits of biotechnologies and management strategies aimed to utilise this abundant reserve of 'legacy' phosphorus. Citrate has been seen to increase phytase catalytic efficiency towards complexed forms of phytate, but the mechanisms by which citrate promotes phytase remains poorly understood. In this study, we evaluated phytase (from Aspergillus niger) inactivation, and change in catalytic properties upon addition to soil and the effect citrate had on adsorption of phytase and hydrolysis towards free, precipitated and adsorbed phytate. A Langmuir model was fitted to phytase adsorption isotherms showing a maximum adsorption of 0.23 nKat g-1 (19 mg protein g-1) and affinity constant of 435 nKat gˉ1 (8.5 mg protein g-1 ), demonstrating that phytase from A.niger showed a relatively low affinity for our test soil (Tayport). Phytases were partially inhibited upon adsorption and the specific activity was of 40.44 nKat mgˉ1 protein for the free enzyme and 25.35 nKat mgˉ1 protein when immobilised. The kinetics of adsorption detailed that most of the adsorption occurred within the first 20 min upon addition to soil. Citrate had no effect on the rate or total amount of phytase adsorption or loss of activity, within the studied citrate concentrations (0-4mM). Free phytases in soil solution and phytase immobilised on soil particles showed optimum activity (>80%) at pH 4.5-5.5. Immobilised phytase showed greater loss of activity at pH levels over 5.5 and lower activities at the secondary peak at pH 2

  14. Plasma catalytic reforming of methane

    Energy Technology Data Exchange (ETDEWEB)

    Bromberg, L.; Cohn, D.R.; Rabinovich, A. [Massachusetts Inst. of Technology, Cambridge, MA (United States). Plasma Science and Fusion Center; Alexeev, N. [Russian Academy of Sciences, Moscow (Russian Federation). Baikov Inst. of Metallurgy

    1998-08-01

    Thermal plasma technology can be efficiently used in the production of hydrogen and hydrogen-rich gases from methane and a variety of fuels. This paper describes progress in plasma reforming experiments and calculations of high temperature conversion of methane using heterogeneous processes. The thermal plasma is a highly energetic state of matter that is characterized by extremely high temperatures (several thousand degrees Celsius) and high degree of dissociation and substantial degree of ionization. The high temperatures accelerate the reactions involved in the reforming process. Hydrogen-rich gas (50% H{sub 2}, 17% CO and 33% N{sub 2}, for partial oxidation/water shifting) can be efficiently made in compact plasma reformers. Experiments have been carried out in a small device (2--3 kW) and without the use of efficient heat regeneration. For partial oxidation/water shifting, it was determined that the specific energy consumption in the plasma reforming processes is 16 MJ/kg H{sub 2} with high conversion efficiencies. Larger plasmatrons, better reactor thermal insulation, efficient heat regeneration and improved plasma catalysis could also play a major role in specific energy consumption reduction and increasing the methane conversion. A system has been demonstrated for hydrogen production with low CO content ({approximately} 1.5%) with power densities of {approximately} 30 kW (H{sub 2} HHV)/liter of reactor, or {approximately} 10 m{sup 3}/hr H{sub 2} per liter of reactor. Power density should further increase with increased power and improved design.

  15. Cosmic Forms

    CERN Document Server

    Kleman, Maurice

    2011-01-01

    The continuous 1D defects of an isotropic homogeneous material in an Euclidean 3D space are classified by a construction method, the Volterra process (VP). We employ the same method to classify the continuous 2D defects (which we call \\textit{cosmic forms}) of a vacuum in a 4D maximally symmetric spacetime. These defects fall into three different classes: i)- $m$-forms, akin to 3D space disclinations, related to ordinary rotations and analogous to Kibble's global cosmic strings (except that being continuous any deficit angle is allowed); ii)- $t$-forms, related to Lorentz boosts (hyperbolic rotations); iii)- $r$-forms, never been considered so far, related to null rotations. A detailed account of their metrics is presented. Their inner structure in many cases appears as a non-singular \\textit{core} separated from the outer part by a timelike hypersurface with distributional curvature and/or torsion, yielding new types of geometrical interactions with cosmic dislocations and other cosmic disclinations. Whereas...

  16. Catalytic coal liquefaction. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Weller, S W

    1981-01-01

    Monolith catalysts of MoO/sub 3/-CoO-Al/sub 2/O/sub 3/ were prepared and tested for coal liquefaction in a stirred autoclave. In general, the monolith catalysts were not as good as particulate catalysts prepared on Corning alumina supports. Measurement of O/sub 2/ chemisorption and BET surface area has been made on a series of Co/Mo/Al/sub 2/O/sub 3/ catalysts obtained from PETC. The catalysts were derived from Cyanamid 1442A and had been tested for coal liquefaction in batch autoclaves and continuous flow units. MoO/sub 3/-Al/sub 2/O/sub 3/ catalysts over the loading range 3.9 to 14.9 wt % MoO/sub 3/ have been studied with respect to BET surface (before and after reduction), O/sub 2/ chemisorption at -78/sup 0/C, redox behavior at 500/sup 0/C, and activity for cyclohexane dehydrogenation at 500/sup 0/C. In connection with the fate of tin catalysts during coal liquefaction, calculations have been made of the relative thermodynamic stability of SnCl/sub 2/, Sn, SnO/sub 2/, and SnS in the presence of H/sub 2/, HCl, H/sub 2/S and H/sub 2/O. Ferrous sulfate dispersed in methylnaphthalene has been shown to be reduced to ferrous sulfide under typical coal hydroliquefaction conditions (1 hour, 450/sup 0/C, 1000 psi initial p/sub H/sub 2//). This suggests that ferrous sulfide may be the common catalytic ingredient when either (a) ferrous sulfate impregnated on powdered coal, or (b) finely divided iron pyrite is used as the catalyst. Old research on impregnated ferrous sulfate, impregnated ferrous halides, and pyrite is consistent with this assumption. Eight Co/Mo/Al/sub 2/O/sub 3/ catalysts from commercial suppliers, along with SnCl/sub 2/, have been studied for the hydrotreating of 1-methylnaphthalene (1-MN) in a stirred autoclave at 450 and 500/sup 0/C.

  17. Challenging a Paradigm: Theoretical Calculations of the Protonation State of the Cys25-His159 Catalytic Diad in Free Papain

    OpenAIRE

    Shokhen, Michael; Khazanov, Netaly; Albeck, Amnon

    2009-01-01

    A central mechanistic paradigm of cysteine proteases is that the His – Cys catalytic diad forms an ion-pair NH(+)/S(−) already in the catalytically active free enzyme. Most molecular modeling studies of cysteine proteases refer to this paradigm as their starting point. Nevertheless, several recent kinetics and X-ray crystallography studies of viral and bacterial cysteine proteases depart from the ion-pair mechanism, suggesting general base catalysis. We challenge the postulate of the ion-pair...

  18. INVESTIGATION OF SELECTIVE CATALYTIC REDUCTION IMPACT ON MERCURY SPECIATION UNDER SIMULATED NOX EMISSION CONTROL CONDITIONS

    Science.gov (United States)

    Selective catalytic reduction (SCR) technology is being increasingly applied for controlling emissions of nitrogen oxides (NOx) from coal-fired boilers. Some recent field and pilot studies suggest that the operation of SCR could affect the chemical form of mercury in the coal com...

  19. Electro-catalytic properties of bi-(Fe and Co shungite composites

    Directory of Open Access Journals (Sweden)

    Bazarbay Serikbayev

    2012-03-01

    Full Text Available The paper presents the results of electrochemical studies obtained on carbon paste electrodes (СPE from Koksu shungite (Ш. The electrochemical and electro-catalytic properties of electrode are compared based on a natural shungite and its modified form with iron and cobalt.

  20. Electro-catalytic properties of bi-(Fe and Co) shungite composites

    OpenAIRE

    Bazarbay Serikbayev; Duisek Kamisbaev; Z. Tilepbergen; O. Ahmet; Zhalgas Uteuliyev

    2012-01-01

    The paper presents the results of electrochemical studies obtained on carbon paste electrodes (СPE) from Koksu shungite (Ш). The electrochemical and electro-catalytic properties of electrode are compared based on a natural shungite and its modified form with iron and cobalt.

  1. Spectral and catalytic properties of aryl-alcohol oxidase, a fungal flavoenzyme acting on polyunsaturated alcohols

    NARCIS (Netherlands)

    Ferreira, P.; Medina, M.; Guillén, F.; Martínez, M.J.; Berkel, van W.J.H.; Martínez, A.T.

    2005-01-01

    Spectral and catalytic properties of the flavoenzyme AAO (aryl-alcohol oxidase) from Pleurotus eryngii were investigated using recombinant enzyme. Unlike most flavoprotein oxidases, AAO does not thermodynamically stabilize a flavin semiquinone radical and forms no sulphite adduct. AAO catalyses the

  2. Direct observation of doping incorporation pathways in self-catalytic GaMnAs nanowires

    DEFF Research Database (Denmark)

    Kasama, Takeshi; Thuvander, M.; Siusys, A.;

    2015-01-01

    Doping mechanisms of Mn in GaAs nanowires (NWs) that have been grown self-catalytically at 600 degrees C by molecular beam epitaxy (MBE) are investigated using advanced electron microscopy techniques and atom probe tomography, Mn is found to be incorporated primarily in the form of non-magnetic t...

  3. Polydimethylsiloxane Coating for a Palladium/MOF Composite: Highly Improved Catalytic Performance by Surface Hydrophobization.

    Science.gov (United States)

    Huang, Gang; Yang, Qihao; Xu, Qiang; Yu, Shu-Hong; Jiang, Hai-Long

    2016-06-20

    Surface wettability of active sites plays a crucial role in the activity and selectivity of catalysts. This report describes modification of surface hydrophobicity of Pd/UiO-66, a composite comprising a metal-organic framework (MOF) and stabilized palladium nanoparticles (NPs), using a simple polydimethylsiloxane (PDMS) coating. The modified catalyst demonstrated significantly improved catalytic efficiency. The approach can be extended to various Pd nanoparticulate catalysts for enhanced activity in reactions involving hydrophobic reactants, as the hydrophobic surface facilitates the enrichment of hydrophobic substrates around the catalytic site. PDMS encapsulation of Pd NPs prevents aggregation of NPs and thus results in superior catalytic recyclability. Additionally, PDMS coating is applicable to a diverse range of catalysts, endowing them with additional selectivity in sieving reactants with different wettability. PMID:27144320

  4. Determination of the catalytic activity of binuclear metallohydrolases using isothermal titration calorimetry.

    Science.gov (United States)

    Pedroso, Marcelo M; Ely, Fernanda; Lonhienne, Thierry; Gahan, Lawrence R; Ollis, David L; Guddat, Luke W; Schenk, Gerhard

    2014-03-01

    Binuclear metallohydrolases are a large and diverse family of enzymes that are involved in numerous metabolic functions. An increasing number of members find applications as drug targets or in processes such as bioremediation. It is thus essential to have an assay available that allows the rapid and reliable determination of relevant catalytic parameters (k cat, K m, and k cat/K m). Continuous spectroscopic assays are frequently only possible by using synthetic (i.e., nonbiological) substrates that possess a suitable chromophoric marker (e.g., nitrophenol). Isothermal titration calorimetry, in contrast, affords a rapid assay independent of the chromophoric properties of the substrate-the heat associated with the hydrolytic reaction can be directly related to catalytic properties. Here, we demonstrate the efficiency of the method on several selected examples of this family of enzymes and show that, in general, the catalytic parameters obtained by isothermal titration calorimetry are in good agreement with those obtained from spectroscopic assays.

  5. A novel liquid system of catalytic hydrogenation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    On the basis that endothermic aqueous-phase reforming of oxygenated hydrocarbons for H2 production and exothermic liquid phase hydrogenation of organic compounds are carried out under extremely close conditions of temperature and pressure over the same type of catalyst, a novel liquid system of catalytic hydrogenation has been proposed, in which hydrogen produced from aqueous-phase reforming of oxygenated hydrocarbons is in situ used for liquid phase hydrogenation of organic compounds. The usage of active hydrogen generated from aqueous-phase reforming of oxygenated hydrocarbons for liquid catalytic hydrogenation of organic compounds could lead to increasing the selectivity to H2 in the aqueous-phase reforming due to the prompt removal of hydrogen on the active centers of the catalyst. Meanwhile, this novel liquid system of catalytic hydrogenation might be a potential method to improve the selectivity to the desired product in liquid phase catalytic hydrogenation of organic compounds. On the other hand, for this novel liquid system of catalytic hydrogenation, some special facilities for H2 generation, storage and transportation in traditional liquid phase hydrogenation industry process are yet not needed. Thus, it would simplify the working process of liquid phase hydrogenation and increase the energy usage and hydrogen productivity.

  6. Efficiency of Vanilla, Patchouli and Ylang Ylang Essential Oils Stabilized by Iron Oxide@C14 Nanostructures against Bacterial Adherence and Biofilms Formed by Staphylococcus aureus and Klebsiella pneumoniae Clinical Strains

    Directory of Open Access Journals (Sweden)

    Maxim Bilcu

    2014-11-01

    Full Text Available Biofilms formed by bacterial cells are associated with drastically enhanced resistance against most antimicrobial agents, contributing to the persistence and chronicization of the microbial infections and to therapy failure. The purpose of this study was to combine the unique properties of magnetic nanoparticles with the antimicrobial activity of three essential oils to obtain novel nanobiosystems that could be used as coatings for catheter pieces with an improved resistance to Staphylococcus aureus and Klebsiella pneumoniae clinical strains adherence and biofilm development. The essential oils of ylang ylang, patchouli and vanilla were stabilized by the interaction with iron oxide@C14 nanoparticles to be further used as coating agents for medical surfaces. Iron oxide@C14 was prepared by co-precipitation of Fe+2 and Fe+3 and myristic acid (C14 in basic medium. Vanilla essential oil loaded nanoparticles pelliculised on the catheter samples surface strongly inhibited both the initial adherence of S. aureus cells (quantified at 24 h and the development of the mature biofilm quantified at 48 h. Patchouli and ylang-ylang essential oils inhibited mostly the initial adherence phase of S. aureus biofilm development. In the case of K. pneumoniae, all tested nanosystems exhibited similar efficiency, being active mostly against the adherence K. pneumoniae cells to the tested catheter specimens. The new nanobiosystems based on vanilla, patchouli and ylang-ylang essential oils could be of a great interest for the biomedical field, opening new directions for the design of film-coated surfaces with anti-adherence and anti-biofilm properties.

  7. Efficiency of vanilla, patchouli and ylang ylang essential oils stabilized by iron oxide@C14 nanostructures against bacterial adherence and biofilms formed by Staphylococcus aureus and Klebsiella pneumoniae clinical strains.

    Science.gov (United States)

    Bilcu, Maxim; Grumezescu, Alexandru Mihai; Oprea, Alexandra Elena; Popescu, Roxana Cristina; Mogoșanu, George Dan; Hristu, Radu; Stanciu, George A; Mihailescu, Dan Florin; Lazar, Veronica; Bezirtzoglou, Eugenia; Chifiriuc, Mariana Carmen

    2014-01-01

    Biofilms formed by bacterial cells are associated with drastically enhanced resistance against most antimicrobial agents, contributing to the persistence and chronicization of the microbial infections and to therapy failure. The purpose of this study was to combine the unique properties of magnetic nanoparticles with the antimicrobial activity of three essential oils to obtain novel nanobiosystems that could be used as coatings for catheter pieces with an improved resistance to Staphylococcus aureus and Klebsiella pneumoniae clinical strains adherence and biofilm development. The essential oils of ylang ylang, patchouli and vanilla were stabilized by the interaction with iron oxide@C14 nanoparticles to be further used as coating agents for medical surfaces. Iron oxide@C14 was prepared by co-precipitation of Fe+2 and Fe+3 and myristic acid (C14) in basic medium. Vanilla essential oil loaded nanoparticles pelliculised on the catheter samples surface strongly inhibited both the initial adherence of S. aureus cells (quantified at 24 h) and the development of the mature biofilm quantified at 48 h. Patchouli and ylang-ylang essential oils inhibited mostly the initial adherence phase of S. aureus biofilm development. In the case of K. pneumoniae, all tested nanosystems exhibited similar efficiency, being active mostly against the adherence K. pneumoniae cells to the tested catheter specimens. The new nanobiosystems based on vanilla, patchouli and ylang-ylang essential oils could be of a great interest for the biomedical field, opening new directions for the design of film-coated surfaces with anti-adherence and anti-biofilm properties.

  8. Efficiency of vanilla, patchouli and ylang ylang essential oils stabilized by iron oxide@C14 nanostructures against bacterial adherence and biofilms formed by Staphylococcus aureus and Klebsiella pneumoniae clinical strains.

    Science.gov (United States)

    Bilcu, Maxim; Grumezescu, Alexandru Mihai; Oprea, Alexandra Elena; Popescu, Roxana Cristina; Mogoșanu, George Dan; Hristu, Radu; Stanciu, George A; Mihailescu, Dan Florin; Lazar, Veronica; Bezirtzoglou, Eugenia; Chifiriuc, Mariana Carmen

    2014-01-01

    Biofilms formed by bacterial cells are associated with drastically enhanced resistance against most antimicrobial agents, contributing to the persistence and chronicization of the microbial infections and to therapy failure. The purpose of this study was to combine the unique properties of magnetic nanoparticles with the antimicrobial activity of three essential oils to obtain novel nanobiosystems that could be used as coatings for catheter pieces with an improved resistance to Staphylococcus aureus and Klebsiella pneumoniae clinical strains adherence and biofilm development. The essential oils of ylang ylang, patchouli and vanilla were stabilized by the interaction with iron oxide@C14 nanoparticles to be further used as coating agents for medical surfaces. Iron oxide@C14 was prepared by co-precipitation of Fe+2 and Fe+3 and myristic acid (C14) in basic medium. Vanilla essential oil loaded nanoparticles pelliculised on the catheter samples surface strongly inhibited both the initial adherence of S. aureus cells (quantified at 24 h) and the development of the mature biofilm quantified at 48 h. Patchouli and ylang-ylang essential oils inhibited mostly the initial adherence phase of S. aureus biofilm development. In the case of K. pneumoniae, all tested nanosystems exhibited similar efficiency, being active mostly against the adherence K. pneumoniae cells to the tested catheter specimens. The new nanobiosystems based on vanilla, patchouli and ylang-ylang essential oils could be of a great interest for the biomedical field, opening new directions for the design of film-coated surfaces with anti-adherence and anti-biofilm properties. PMID:25375335

  9. Formation of Catalytic Metal-Molecule Contacts

    Science.gov (United States)

    Tulevski, George S.; Myers, Matt B.; Hybertsen, Mark S.; Steigerwald, Michael L.; Nuckolls, Colin

    2005-07-01

    We describe a new strategy for the in situ growth of molecular wires predicated on the synthesis of a trifunctional ``primed'' contact formed from metal-carbon multiple bonds. The ruthenium-carbon π bond provides structural stability to the molecular linkages under ambient conditions, and density functional calculations indicate the formation of an efficient conduit for charge carriers to pass between the metal and the molecule. Moreover, the metal-carbon π bond provides a chemically reactive site from which a conjugated molecular wire can be grown in situ through an olefin metathesis reaction.

  10. Effect of preparation parameters on catalytic properties of Pt/graphite

    Institute of Scientific and Technical Information of China (English)

    LIU Zhengqian; MA Jun; ZHAO Lei

    2007-01-01

    Catalytic ozonation of aqueous solutions of oxalic acid was examined in the presence of graphite-supported platinum catalysts.The catalytic activity of graphite was significantly enhanced by loading platinum.The removal efficiency of oxalic acid was 3.0%,47.6% and 99.3% for ozonation alone,graphite catalytic ozonation and Pt/graphite catalytic ozonation in 30 min under the experimental condition,respectively.The influence of support pretreatment,solvent,impregnation time,platinum loading amount and reduction temperature on the activity of Pt/graphite catalyst was investigated.The pretreatment of graphite support had no effect on activity improvement of Pt/graphite catalyst.Solvent and impregnation time also had no great effect on the activity.Platinum loading amount and reduction temperature influenced the catalyst activity significantly.The optimal catalytic performance of Pt/graphite was obtained when 1.0% platinum loading and 623 K of reduction temperature was adopted.The Pt/graphite catalyst was used for five times with no significant decrease in its activity and more than 90% oxalic acid removal was obtained.

  11. Improvement of catalytical properties of two invertases highly tolerant to sucrose after expression in Pichia pastoris. Effect of glycosylation on enzyme properties.

    Science.gov (United States)

    Pérez de los Santos, Ara Itzel; Cayetano-Cruz, Maribel; Gutiérrez-Antón, Marina; Santiago-Hernández, Alejandro; Plascencia-Espinosa, Miguel; Farrés, Amelia; Hidalgo-Lara, María Eugenia

    2016-02-01

    Zymomonas mobilis genes encoding INVA and INVB were expressed in Pichia pastoris, under the control of the strong AOX1 promoter, and the recombinant enzymes were named INVAAOX1 and INVBAOX1. The expression levels of INVAAOX1 (1660 U/mg) and INVBAOX1 (1993 U/mg) in P. pastoris were 9- and 7-fold higher than those observed for the native INVA and INVB proteins in Z. mobilis. INVAAOX1 and INVBAOX1 displayed a 2- to 3-fold higher substrate affinity, and a 2- to 200-fold higher catalytic efficiency (kcat/KM) than that observed for native INVA and INVB from Z. mobilis. Positive Schiff staining of INVAAOX1 and INVBAOX1 suggested a glycoprotein nature of both invertases. After deglycosylation of these enzymes, denoted D-INVAAOX1 and D-INVBAOX1, they exhibited a 1.3- and 3-fold lower catalytic efficiency (107 and 164 s(-1) mM(-1), respectively), and a 1.3- to 5-fold lower thermal stability than the glycosylated forms at temperatures of 35-45 °C. After deglycosylation no effect was observed in optimal pH, being of 5.5 for INVAAOX1, INVBAOX1, D-INVAAOX1 and D-INVBAOX1. The invertase activity of both enzymes increased in 80% (INVAAOX1) and 20% (INVBAOX1) in the presence of Mn(2+) at 1 mM and 5 mM, respectively. INVAAOX1 and INVBAOX1 were highly active at sucrose concentrations of up to 400 and 300 mM, respectively; however, the tolerance to sucrose decreased to 300 mM for D-INVAAOX1. Our findings suggest that glycosylation of INVAAOX1 and INVBAOX1 plays an important role in their thermal stability, catalytic efficiency, and tolerance to sucrose. In conclusion, the expression of INVA and INVB from Z. mobilis in P. pastoris yields new catalysts with improved catalytic properties, making them suitable candidates for a number of industrial applications or for the improvement of ethanol production from cane molasses.

  12. Improvement of catalytical properties of two invertases highly tolerant to sucrose after expression in Pichia pastoris. Effect of glycosylation on enzyme properties.

    Science.gov (United States)

    Pérez de los Santos, Ara Itzel; Cayetano-Cruz, Maribel; Gutiérrez-Antón, Marina; Santiago-Hernández, Alejandro; Plascencia-Espinosa, Miguel; Farrés, Amelia; Hidalgo-Lara, María Eugenia

    2016-02-01

    Zymomonas mobilis genes encoding INVA and INVB were expressed in Pichia pastoris, under the control of the strong AOX1 promoter, and the recombinant enzymes were named INVAAOX1 and INVBAOX1. The expression levels of INVAAOX1 (1660 U/mg) and INVBAOX1 (1993 U/mg) in P. pastoris were 9- and 7-fold higher than those observed for the native INVA and INVB proteins in Z. mobilis. INVAAOX1 and INVBAOX1 displayed a 2- to 3-fold higher substrate affinity, and a 2- to 200-fold higher catalytic efficiency (kcat/KM) than that observed for native INVA and INVB from Z. mobilis. Positive Schiff staining of INVAAOX1 and INVBAOX1 suggested a glycoprotein nature of both invertases. After deglycosylation of these enzymes, denoted D-INVAAOX1 and D-INVBAOX1, they exhibited a 1.3- and 3-fold lower catalytic efficiency (107 and 164 s(-1) mM(-1), respectively), and a 1.3- to 5-fold lower thermal stability than the glycosylated forms at temperatures of 35-45 °C. After deglycosylation no effect was observed in optimal pH, being of 5.5 for INVAAOX1, INVBAOX1, D-INVAAOX1 and D-INVBAOX1. The invertase activity of both enzymes increased in 80% (INVAAOX1) and 20% (INVBAOX1) in the presence of Mn(2+) at 1 mM and 5 mM, respectively. INVAAOX1 and INVBAOX1 were highly active at sucrose concentrations of up to 400 and 300 mM, respectively; however, the tolerance to sucrose decreased to 300 mM for D-INVAAOX1. Our findings suggest that glycosylation of INVAAOX1 and INVBAOX1 plays an important role in their thermal stability, catalytic efficiency, and tolerance to sucrose. In conclusion, the expression of INVA and INVB from Z. mobilis in P. pastoris yields new catalysts with improved catalytic properties, making them suitable candidates for a number of industrial applications or for the improvement of ethanol production from cane molasses. PMID:26777250

  13. Designing functional metalloproteins: from structural to catalytic metal sites.

    Science.gov (United States)

    Zastrow, Melissa L; Pecoraro, Vincent L

    2013-09-01

    Metalloenzymes efficiently catalyze some of the most important and difficult reactions in nature. For many years, coordination chemists have effectively used small molecule models to understand these systems. More recently, protein design has been shown to be an effective approach for mimicking metal coordination environments. Since the first designed proteins were reported, much success has been seen for incorporating metal sites into proteins and attaining the desired coordination environment but until recently, this has been with a lack of significant catalytic activity. Now there are examples of designed metalloproteins that, although not yet reaching the activity of native enzymes, are considerably closer. In this review, we highlight work leading up to the design of a small metalloprotein containing two metal sites, one for structural stability (HgS3) and the other a separate catalytic zinc site to mimic carbonic anhydrase activity (ZnN3O). The first section will describe previous studies that allowed for a high affinity thiolate site that binds heavy metals in a way that stabilizes three-stranded coiled coils. The second section will examine ways of preparing histidine rich environments that lead to metal based hydrolytic catalysts. We will also discuss other recent examples of the design of structural metal sites and functional metalloenzymes. Our work demonstrates that attaining the proper first coordination geometry of a metal site can lead to a significant fraction of catalytic activity, apparently independent of the type of secondary structure of the surrounding protein environment. We are now in a position to begin to meet the challenge of building a metalloenzyme systematically from the bottom-up by engineering and analyzing interactions directly around the metal site and beyond.

  14. Influence of Al content on textural properties and catalytic activity of hierarchical porous aluminosilicate materials

    Indian Academy of Sciences (India)

    Ling Xu; Limei Duan; Zongrui Liu; Jingqi Guan; Qiubin Kan

    2013-12-01

    A series of hierarchical porous aluminosilicate materials were prepared using hydrothermal treatment of the composite formed by polystyrene colloidal spheres and aluminosilicate gel. Influence of Al content on the textural properties, acidic properties and catalytic activity of the hierarchical porous aluminosilicate materials was studied. The results showed that textural and acidic properties of the hierarchical porous aluminosilicate materials were strongly related to Al content. As Al content is increased (Si/Al = 25), the hierarchical porous catalysts exhibited higher catalytic activity and major product selectivity for alkylation of phenol with tert-butanol than the catalysts with a lower Al content (Si/Al = 50).

  15. Radiation-catalytical properties of natural zeolite of mordenite type during radiolysis of water

    International Nuclear Information System (INIS)

    Radiation-catalytic properties of natural zeolite of mordenite type in cation Na+, K+, Ca2+, Ba2+ forms during radiolysis of water molecules were investigated with the use of 60Co γ-radiation (6 Gy/s). Kinetic parameters of radiolysis of water molecules in the presence of these zeolite samples were determined. It was revealed that zeolite of mordenite type catalyzes the radiolysis water molecules, its catalytic activity growing with decrease in ionic radius of the cation in the zeolite composition

  16. Catalytic Combustion of Methane over Ti-Pillared Clay Supported Copper Catalysts

    Institute of Scientific and Technical Information of China (English)

    Xiufeng Xu; Yanfei Pan; Xiaoyan Cui; Zhanghuai Suo

    2004-01-01

    A natural montmorillonite, produced from Laiyang of Shandong Province, was pillared by Tipolycations to form Ti-pillared clay (Ti-PILC), and characterized by BET surface area, infrared spectra and thermal analysis. The characterization results show that Ti-PILC has a larger surface area and more hydroxyl groups than that of the natural clay, thus was used as the catalytic carriers to prepare supported Cu catalysts (Cu/Ti-PILC). The 20%Cu/Ti-PILC with 10mmol/g of Ti/clay shows a high catalytic performance of methane combustion in the temperature range of 400-500 ℃.

  17. ADAR proteins: structure and catalytic mechanism.

    Science.gov (United States)

    Goodman, Rena A; Macbeth, Mark R; Beal, Peter A

    2012-01-01

    Since the discovery of the adenosine deaminase (ADA) acting on RNA (ADAR) family of proteins in 1988 (Bass and Weintraub, Cell 55:1089-1098, 1988) (Wagner et al. Proc Natl Acad Sci U S A 86:2647-2651, 1989), we have learned much about their structure and catalytic mechanism. However, much about these enzymes is still unknown, particularly regarding the selective recognition and processing of specific adenosines within substrate RNAs. While a crystal structure of the catalytic domain of human ADAR2 has been solved, we still lack structural data for an ADAR catalytic domain bound to RNA, and we lack any structural data for other ADARs. However, by analyzing the structural data that is available along with similarities to other deaminases, mutagenesis and other biochemical experiments, we have been able to advance the understanding of how these fascinating enzymes function. PMID:21769729

  18. Catalytic Organic Transformations Mediated by Actinide Complexes

    Directory of Open Access Journals (Sweden)

    Isabell S. R. Karmel

    2015-10-01

    Full Text Available This review article presents the development of organoactinides and actinide coordination complexes as catalysts for homogeneous organic transformations. This chapter introduces the basic principles of actinide catalysis and deals with the historic development of actinide complexes in catalytic processes. The application of organoactinides in homogeneous catalysis is exemplified in the hydroelementation reactions, such as the hydroamination, hydrosilylation, hydroalkoxylation and hydrothiolation of alkynes. Additionally, the use of actinide coordination complexes for the catalytic polymerization of α-olefins and the ring opening polymerization of cyclic esters is presented. The last part of this review article highlights novel catalytic transformations mediated by actinide compounds and gives an outlook to the further potential of this field.

  19. Reactivity of organic compounds in catalytic synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Minachev, Kh.M.; Bragin, O.V.

    1978-01-01

    A comprehensive review of 1976 Soviet research on catalysis delivered to the 1977 annual session of the USSR Academy of Science Council on Catalysis (Baku 6/16-20/77) covers hydrocarbon reactions, including hydrogenation and hydrogenolysis, dehydrogenation, olefin dimerization and disproportionation, and cyclization and dehydrocyclization (e.g., piperylene cyclization and ethylene cyclotrimerization); catalytic and physicochemical properties of zeolites, including cracking, dehydrogenation, and hydroisomerization catalytic syntheses and conversion of heterocyclic and functional hydrocarbon derivatives, including partial and total oxidation (e.g., of o-xylene to phthalic anhydride); syntheses of thiophenes from alkanes and hydrogen sulfide over certain dehydrogenation catalysts; catalytic syntheses involving carbon oxides ( e.g., the development of a new heterogeneous catalyst for hydroformylation of olefins), and of Co-MgO zeolitic catalysts for synthesis of aliphatic hydrocarbons from carbon dioxide and hydrogen, and fabrication of high-viscosity lubricating oils over bifunctional aluminosilicate catalysts.

  20. Catalytic microreactors for portable power generation

    Energy Technology Data Exchange (ETDEWEB)

    Karagiannidis, Symeon [Paul Scherer Institute, Villigen (Switzerland)

    2011-07-01

    ''Catalytic Microreactors for Portable Power Generation'' addresses a problem of high relevance and increased complexity in energy technology. This thesis outlines an investigation into catalytic and gas-phase combustion characteristics in channel-flow, platinum-coated microreactors. The emphasis of the study is on microreactor/microturbine concepts for portable power generation and the fuels of interest are methane and propane. The author carefully describes numerical and experimental techniques, providing a new insight into the complex interactions between chemical kinetics and molecular transport processes, as well as giving the first detailed report of hetero-/homogeneous chemical reaction mechanisms for catalytic propane combustion. The outcome of this work will be widely applied to the industrial design of micro- and mesoscale combustors. (orig.)