Добірка наукової літератури з теми "Selective internal oxidation"
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Статті в журналах з теми "Selective internal oxidation"
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Hou, P. Y., Z. R. Shui, and J. Stringer. "Oxidation Behavior of Co-15wt% Cr Alloy Containing Dispersed Oxides Formed by Internal Oxidation." Corrosion 48, no. 12 (December 1, 1992): 990–1000. http://dx.doi.org/10.5006/1.3315911.
Повний текст джерелаАнотація:
Abstract Internal oxidation pretreatments of Co-15wt%Cr and Co-15wt%Cr-1 wt% Ti were carried out using a Rhines pack in quartz, in mullite, and in alumina. A dispersion of titanium oxide particles formed in the Ti-containing alloy as a result of the internal oxidation. However, silicon also diffused into all treated specimens when the pretreatments were carried out in quartz or in mullite. The effect of various pretreatments on the subsequent oxidation of these alloys was studied at 1,000°C and compared with that of a Co-15wt%Cr-1wt%Si alloy. The main purpose of this study was to determine the relative effectiveness of the dispersed oxide particles and the contaminated silicon on the selective oxidation of chromium. It was found that the oxidation behaviors of both treated alloys were strongly affected by the degree of silicon contamination. Selective oxidation of chromium to form a nearly continuous protective Cr2O3 scale was achieved with greater than 0.4 wt% silicon. The presence of dispersed particles reduced initial oxidation rate but was ineffective in promoting Cr2O3 scale formation.
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Zimbitas, Georgina, and Willem G. Sloof. "Modeling Internal Oxidation of Binary Ni Alloys." Materials Science Forum 696 (September 2011): 82–87. http://dx.doi.org/10.4028/www.scientific.net/msf.696.82.
Повний текст джерелаАнотація:
A numerical model is presented to simulate the diffusional transport of oxygen and that of an alloying element, within a 1-D binary Ni alloy, leading to the selective oxidation of the alloying element and the formation of an internal oxide precipitate. This specific model is written in MATLAB and, with the aid of the Matlab Toolbox, is coupled to the ThermoCalc extensive database. A reaction time is introduced to overcome problems related to the difficulty of formation of the internal oxide. Two cases are considered: Al as the alloying element for which the solubility product of the oxide forming elements is small, and Mn for which it is large.
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Kogo, Yasuo, Yoshie Iijima, and Naohiro Igata. "Enhancement of internal friction of carbon–carbon composites by selective oxidation." Journal of Alloys and Compounds 355, no. 1-2 (June 2003): 154–60. http://dx.doi.org/10.1016/s0925-8388(03)00255-x.
Повний текст джерела
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Wen, Jiangwei, Longfei Zhang, Xiaoting Yang, Cong Niu, Shuangfeng Wang, Wei Wei, Xuejun Sun, Jianjing Yang, and Hua Wang. "H2O-controlled selective thiocyanation and alkenylation of ketene dithioacetals under electrochemical oxidation." Green Chemistry 21, no. 13 (2019): 3597–601. http://dx.doi.org/10.1039/c9gc01351b.
Повний текст джерелаАнотація:
Efficient and H2O-controlled selective thiocyanation and alkenylation of internal olefins, to afford tetrasubstituted olefins under electrochemical oxidation, has been successfully developed.
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Cho, Lawrence, Geun Su Jung, and Bruno C. De Cooman. "On the Transition of Internal to External Selective Oxidation on CMnSi TRIP Steel." Metallurgical and Materials Transactions A 45, no. 11 (July 18, 2014): 5158–72. http://dx.doi.org/10.1007/s11661-014-2442-7.
Повний текст джерела
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Glickstein, James J., Paul A. Salvador, and Gregory S. Rohrer. "Multidomain simulations of coated ferroelectrics exhibiting spatially selective photocatalytic activity with high internal quantum efficiencies." Journal of Materials Chemistry A 4, no. 41 (2016): 16085–93. http://dx.doi.org/10.1039/c6ta07083c.
Повний текст джерела
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Wang, Zi Jun, Saman Ghasimi, Katharina Landfester, and Kai A. I. Zhang. "Highly porous conjugated polymers for selective oxidation of organic sulfides under visible light." Chem. Commun. 50, no. 60 (2014): 8177–80. http://dx.doi.org/10.1039/c4cc02861a.
Повний текст джерелаАнотація:
High surface area porous conjugated polymers were synthesized via the high internal phase emulsion polymerization technique and micropore engineering as efficient heterogeneous photocatalysts for highly selective oxidation of organic sulfides to sulfoxides under visible light.
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Teng, Hua Xiang, Hai Quan Wang, Guang Hui Liu, Guang Rui Jiang, Li Bin Liu, and Yong Lin Kang. "Analysis on Alloying Elements of Selective Oxidation of TRIP Steel." Advanced Materials Research 941-944 (June 2014): 206–11. http://dx.doi.org/10.4028/www.scientific.net/amr.941-944.206.
Повний текст джерелаАнотація:
Two kinds of TRIP steel with different Al and Si content were researched in this article. Different annealing atmosphere in the trial was achieved by the Hot Dip Galvanized Simulator by Iwatani. The segregation of alloying elements after annealing under different atmosphere were investigated and the compounds on the surface were shown. Furhermore, the distribution of oxides was abserved on the surface and the reactive wetting was assessed and the results after galvanizing was provided. We found out the increasing wettability was abserved under more reducing atmosphere with less Si because of a decrease oxide amount and an increase internal oxidation.
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Moghe, Keerti, A. K. Sutar, I. K. Kang, and K. C. Gupta. "Poly(vinylbenzyl chloride-co-divinyl benzene) polyHIPE monolith-supported o-hydroxynaphthaldehyde propylenediamine Schiff base ligand complex of copper(ii) ions as a catalyst for the epoxidation of cyclohexene." RSC Advances 9, no. 53 (2019): 30823–34. http://dx.doi.org/10.1039/c9ra05811g.
Повний текст джерелаАнотація:
High internal phase emulsion of vinyl benzene and divinyl benzene in aqueous calcium chloride produced porous monoliths,which improved the activity of supported HNPn-Cu catalyst in selective oxidation of cyclohexene in presence hydrogen peroxide.
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Swaminathan, Srinivasan, and Michael Rohwerder. "Role of Forming Gas Annealing Characteristics on the Selective Surface Oxidation of Fe-Mn-Si-Cr Model Alloy." Defect and Diffusion Forum 312-315 (April 2011): 918–23. http://dx.doi.org/10.4028/www.scientific.net/ddf.312-315.918.
Повний текст джерелаАнотація:
To understand the role of annealing conditions on the segregation and selective oxidation phenomena, Fe 2Mn 2Si 0.8Cr (all in wt.%) model alloy was investigated. The samples were annealed at 820°C in N2-5%H2 forming gas atmospheres over a wide range of dew pints (-80 to 0°C) with dwelling time of 1 to 5 minutes. At all dew points, the strong chemical interaction between Mn and Si causes the formation of manganese silicates. External oxidation of Mn, Si and Cr were decreased at the higher dew points. Increasing the dwelling time shows an extended oxidation front i.e. pronounced external/internal oxidation of Mn, Si and Cr. Basically, the present work addresses the two stages of oxidation front.
Дисертації з теми "Selective internal oxidation"
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Kachur, Stephen J. "Selective Internal Oxidation and Severe Plastic Deformation of Multiphase Fe-Y Alloys." Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/1013.
Повний текст джерелаАнотація:
Oxide dispersion strengthened (ODS) alloys are known for their desirable mechanical properties and unique microstructures. These alloys are characterized by an even dispersion of oxide phase throughout a metallic matrix, and exhibit high strength and enhanced creep properties at elevated temperatures. This makes them ideal candidate materials for use in many structural applications, such as coal-fired power plants or in next generation nuclear reactors. Currently most often produced by mechanical alloying, a powder metallurgy based process that utilizes high energy ball milling, these alloys are difficult and costly to produce. One proposed method for forming ODS alloys without high-energy ball milling is to internally oxidize a bulk alloy before subjecting it to severe plastic deformation to induce an even oxide distribution. This work examines such a processing scheme with a focus on the internal oxidation behavior. Internal oxidation has been shown to occur orders of magnitude faster than expected in multi-phase alloys where a highly reactive oxidizable solute has negligible solubility and diffusivity in other, more-noble, phases. Commonly referred to as in situ oxidation, this accelerated oxidation process has potential for use in a processing scheme for ODS alloys. While in situ oxidation has been observed in many different alloy systems, a comprehensive study of alloy composition and microstructure has not been performed to describe the unusual oxidation rates. This work used Fe-Y binary alloys as model system to study effects of composition and microstructure. These alloys have been shown to exhibit in situ oxidation, and additionally, Y is typically introduced during mechanical alloying to form Y-rich oxides in Fe-based ODS alloys. Alloys with Y content between 1.5 and 15 wt% were prepared using a laboratory scale arc-melting furnace. These alloys were two phase mixtures of Fe and Fe17Y2. First, samples were oxidized between 600 and 800 °C for 2 to 72 hours, using a Rhines pack to maintain low oxygen partial pressures so that in situ oxidation could occur. Oxidation rates were accelerated when compared to traditional theory, and were not well described by a single parabolic rate constant throughout the duration of the experiment. While results agreed with Wagner theory that increased Y content should lead to decreased oxidation rates, this was attributed to a depletion of oxygen supply from the Rhines pack over time. Samples were also subjected to plastic deformation to observe how changes in microstructure influenced kinetics. Connectivity of the oxidizable phase was found to be critical to promoting the fastest rates of oxidation. Oxidation studies where then carried out using thermogravimetric analysis. A gaseous mixture of Ar-H2 was passed through a dew point control unit to vary oxidant partial pressure between 10-25 and 10-20 atm. Flow rate of the gas parallel to the sample surface was also altered. Canonical correlation analysis was then used to analyze and simplify the relationships between input and output variables. This analysis pointed to the importance of quantifying the relationship between the size of formed oxides and changes in oxidation kinetics over time. Where sustained parabolic kinetics were observed, oxides were small throughout the depth of internal oxidation. The effects of oxide size on penetration depth were then numerically modeled and incorporated into existing oxidation theory to show that the observed kinetics could be qualitatively described. After oxidation experiments, severe plastic deformation was applied to both oxidized and unoxidized microstructures using equal channel angular pressing. By manipulating pressing temperature and the number of passes, microstructures were altered to varying degrees of success. No oxide refinement was observed, but increasing temperatures and number of passes allowed for even dispersion of both oxides and Fe17Y2 intermetallic.
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Chen, Meng-Hsien. "A STUDY OF SELECTIVE SURFACE AND INTERNAL OXIDATION OF ADVANCED HIGH STRENGTH STEEL GRADES." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1401380512.
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Agrizzi, Ronqueti Larissa. "Study of grain boundary oxidation of high alloyed carbon steels at coiling temperature." Thesis, Compiègne, 2018. https://bibliotheque.utc.fr/Default/doc/SYRACUSE/2018COMP2405.
Повний текст джерелаАнотація:
Les aciers à haute résistance (AHSS) ont été largement utilisés dans le cadre d’applications automobiles visant à améliorer la sécurité et l’allègement des structures. Afin d'atteindre les objectifs en termes de propriétés mécaniques, ces nouveaux aciers sont composés de teneurs en éléments d’alliages beaucoup plus élevés (par exemple silicium et manganèse) que les aciers usuels. En conséquence, l'AHSS est susceptible de subir une oxydation interne sélective lors du refroidissement des bobines d’acier. L'oxydation sélective interne, en particulier l'oxydation aux joints de grains (GBO), est actuellement l'un des principaux obstacles à la production de ces aciers. Elle réduit le nombre de cycles avant la rupture de fatigue et rend ainsi difficile l’obtention des spécifications du client. Par conséquent, ce travail de thèse était axé sur l'effet de plusieurs paramètres sur le comportement à l’oxydation interne sélective. Parmi eux, l'impact de la décarburation, l'influence de la température de bobinage et de la couche de calamine, l'effet de différentes teneurs en silicium et / ou en manganèse et leur comportement en diffusion. De plus, l'impact de la désorientation des joints de grains sur l'oxydation interne a également été étudié. Des alliages modèles à base de fer binaires / ternaires ainsi que des aciers industriels ont été étudiés via un large ensemble de techniques expérimentales. Ces analyses ont mis en évidence une décarburation stable pour tous les échantillons étudiés qui n'a pas d'impact sur l'oxydation interne sélective pour une longue exposition aux conditions isothermes. Les profondeurs d’oxydation aux joints de grain ont été examinées selon les différentes configurations de tests et se sont révélées sensibles aux teneurs en silicium ou en manganèse. Pour certaines d'entre elles, différents comportements de diffusion du silicium ont été identifiés vis-à-vis de l'oxydation des joints de grains, en fonction des températures. Considérant quelques hypothèses restrictives, l'application de la théorie de l'oxydation interne sélective de Wagner a permis de déterminer le coefficient de diffusion de l'oxygène aux joints de grain. Pour surmonter certaines limites du modèle de Wagner, un modèle d'oxydation sélective a été appliqué pour comprendre l'effet de différents paramètres sur la pénétration de l'oxygène à l'intérieur du métal et principalement sur la profondeur des joints de grain affectée par l'oxydation sélective. Les connaissances acquises à partir de ce travail de thèse aideront à comprendre et à limiter l'oxydation sélective interne (principalement l’oxydation aux joints de grain) dans les aciers avec des compositions complexes en éléments d’alliage. En outre, les résultats peuvent être utilisés pour évaluer les paramètres d’un modèle d'oxydation sélectiveAdvanced high-strength steels (AHSS) have been widely used in automotive industry to improve safety and fuel economy. In order to reach the mechanical properties targets, these new steels are composed by much higher alloy contents (e.g. silicon and manganese) than usual steels. As consequence, the AHSS may suffer of selective internal oxidation during the cooling of hot coil. The selective internal oxidation, especially the grain boundary oxidation (GBO), is currently one of the main obstacles to the production of these steels. It reduces the number of cycles before fatigue failure and thus, makes it difficult to reach the specifications of the customer. Therefore, this PhD work was focused on the effect of several parameters on selective internal oxidation behavior. Among them, the impact of decarburization, the influence of coiling temperature and the mill scale, the effect of different silicon and/or manganese contents and their diffusion behavior. Moreover, the impact of grain boundary misorientation on grain boundary oxidation was also investigated. Either binary/ternary iron-based model alloys as well as industrial steels were investigated by a large set of experimental techniques. This analysis showed a stable decarburization for all investigated samples that does not impact the selective internal oxidation for long exposure time in isothermal conditions. The GBO depths were examined according to the different test configurations and were found dependent for some cases on silicon or manganese content. For some of them, different silicon diffusion behaviors were identified with regards to grain boundary oxidation depending on temperatures. Considering some restrictive hypotheses, the application of Wagner’s theory of selective internal oxidation allowed determining the grain boundary diffusion coefficient of oxygen. To overcome some limitations of Wagner’s model, a model of selective oxidation has been applied to understand the effect of different parameters on the penetration of oxygen inside the metal and principally on the grain boundary depth affected by selective oxidation. The knowledge acquired from this PhD work will help to understand and limit the selective internal oxidation (mainly GBO) in new steels with complex alloy compositions. Furthermore, the results may be used to assess a model of selective oxidation
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Wang, Ling, Mary E. A. Howell, Aryianna Sparks Wallace, Caroline Hawkins, Camri A. Nicksic, Carissa Kohne, Kenton H. Hall, Jonathan P. Moorman, Zhi Q. Yao, and Shunbin Ning. "p62-mediated Selective Autophagy Endows Virus-Transformed Cells With Insusceptibility to DNA Damage Under Oxidative Stress." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/etsu-works/6521.
Повний текст джерелаАнотація:
DNA damage response (DDR) and selective autophagy both can be activated by reactive oxygen/nitrogen species (ROS/RNS), and both are of paramount importance in cancer development. The selective autophagy receptor and ubiquitin (Ub) sensor p62 plays a key role in their crosstalk. ROS production has been well documented in latent infection of oncogenic viruses including Epstein-Barr Virus (EBV). However, p62-mediated selective autophagy and its interplay with DDR have not been investigated in these settings. In this study, we provide evidence that considerable levels of p62-mediated selective autophagy are spontaneously induced, and correlate with ROS-Keap1-NRF2 pathway activity, in virus-transformed cells. Inhibition of autophagy results in p62 accumulation in the nucleus, and promotes ROS-induced DNA damage and cell death, as well as downregulates the DNA repair proteins CHK1 and RAD51. In contrast, MG132-mediated proteasome inhibition, which induces rigorous autophagy, promotes p62 degradation but accumulation of the DNA repair proteins CHK1 and RAD51. However, pretreatment with an autophagy inhibitor offsets the effects of MG132 on CHK1 and RAD51 levels. These findings imply that p62 accumulation in the nucleus in response to autophagy inhibition promotes proteasome-mediated CHK1 and RAD51 protein instability. This claim is further supported by the findings that transient expression of a p62 mutant, which is constitutively localized in the nucleus, in B cell lines with low endogenous p62 levels recaptures the effects of autophagy inhibition on CHK1 and RAD51 protein stability. These results indicate that proteasomal degradation of RAD51 and CHK1 is dependent on p62 accumulation in the nucleus. However, small hairpin RNA (shRNA)-mediated p62 depletion in EBV-transformed lymphoblastic cell lines (LCLs) had no apparent effects on the protein levels of CHK1 and RAD51, likely due to the constitutive localization of p62 in the cytoplasm and incomplete knockdown is insufficient to manifest its nuclear effects on these proteins. Rather, shRNA-mediated p62 depletion in EBV-transformed LCLs results in significant increases of endogenous RNF168-γH2AX damage foci and chromatin ubiquitination, indicative of activation of RNF168-mediated DNA repair mechanisms. Our results have unveiled a pivotal role for p62-mediated selective autophagy that governs DDR in the setting of oncogenic virus latent infection, and provide a novel insight into virus-mediated oncogenesis.
Частини книг з теми "Selective internal oxidation"
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Taber, Douglass F. "C–H Functionalization: The Shaw Synthesis of E-δ-Viniferin." In Organic Synthesis. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190646165.003.0022.
Повний текст джерелаАнотація:
Thomas Lectka of Johns Hopkins University reported (J. Org. Chem. 2014, 79, 8895) a simple protocol for free radical monofluorination, exemplified by the conversion of 1 to 2. Michael K. Hilinski of the University of Virginia used (Org. Lett. 2014, 16, 6504) a catalytic amount of the ketone 4 to mediate the oxidation of 3 to 5. Oxidation of 3 with DMDO gave the regioisomeric tertiary alcohol (not illustrated). Jeung Gon Kim and Sukbok Chang of KAIST used (Chem. Commun. 2014, 50, 12073) an Ir catalyst to convert 6 selectively to the primary sulfonamide 7. Paul J. Chirik of Princeton University employed (J. Am. Chem. Soc. 2014, 136, 12108) a Co catalyst to effect the migration of the internal alkene of 8 to the terminal alkene, that then underwent dehydrogenative silylation with 9 to deliver the allyl silane 10. Jiang Cheng of Changzhou University developed (J. Org. Chem. 2014, 79, 9847) conditions for the aminoalkylation of cyclohexane 11 with 12 to give 13. Ilhyong Ryu of Osaka Prefecture University and Maurizio Fagnoni of the University of Pavia observed (Chem. Sci. 2014, 5, 2893) high selectivity in the addition of 14 to 15. Of the five possible regioisomers, 16 dominated. In another light-mediated transformation, Shin Kamijo of Yamaguchi University and Masayuki Inoue of the University of Tokyo added (Chem. Sci. 2014, 5, 4339) 17 to 18 to give 19. Huw M. L. Davies of Emory University established (J. Am. Chem. Soc. 2014, 136, 17718) conditions for the enantioselective alkylation of a methyl ether 21 with 20 to give the ester 22. Selective methyl insertion was observed even with much more complex substrates. The trichloroethyl ester was critical for this transformation. James A. Bull of Imperial College London effected (Org. Lett. 2014, 16, 4956) selective cis-arylation of the proline-derived amide 23 with 24 to give 25. E. Peter Kündig of the University of Geneva coupled (Chem. Eur. J. 2014, 20, 15021) the amine 27 with 26, then cyclized that product to the indoline 28. The enantiomeric Pd catalyst delivered the regioisomeric C–H insertion product.
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Taber, Douglass F. "Alkene Reactions: The Xu/Loh Synthesis of Vitamin A1." In Organic Synthesis. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190646165.003.0028.
Повний текст джерелаАнотація:
Abdolreza Rezaeifard and Maasoumeh Jafarpour of the University of Birjand devised (J. Am. Chem. Soc. 2013, 135, 10036) an easily-scaled protocol for the Mo-catalyzed “on water” epoxidation of an alkene 1 to 2, using molecular O₂. Needing to epoxidize the sensitive alkene 3 to 5, Douglass F. Taber of the University of Delaware developed (Org. Synth. 2013, 90, 350) a convenient preparation of mmol quantities of the versatile oxidant dimethyldioxirane 4. Robert H. Grubbs of Caltech showed (Angew. Chem. Int. Ed. 2013, 52, 9751) that the Wacker oxidation of internal alkenes could proceed with high regioselectivity, as exemplified by the conversion of 6 to 7. David A. Nicewicz of the University of North Carolina demonstrated (J. Am. Chem. Soc. 2013, 135, 10334) the remarkable anti-Markovnikov addition of the acid 9 to the alkene 8, to give 10. Pieter C. A. Bruijnincx and Robertus J. M. Klein Gebbink of the University of Utrecht established (Chem. Eur. J. 2013, 19, 15012) a robust one-pot protocol for epoxidation, epoxide hydrolysis and periodate cleavage, for the net oxidative cleavage of the alkene 11 to the aldehydes 12 and 13. Tomoki Ogoshi of Kanazawa University observed (Org. Lett. 2013, 15, 3742) that permanganate with a phase transfer catalyst could selectively oxidize the linear alkene 14 to 15 in the presence of branched alkenes. Davood Azarifar of Bu-Ali Sina University devised (Synlett 2013, 24, 1377) the reagent 17 as a useful alternative to ozone, as illustrated by the oxidation of 16 to 18. Ning Jiao of Peking University effected (J. Am. Chem. Soc. 2013, 135, 11692) the unsymmetrical cleavage of the alkene 19 to the nitrile aldehyde 20. Tiow-Gan Ong of the Academia Sinica added (Org. Lett. 2013, 15, 5358) 22 to the alkene 21 to give the linear product 23. This could be hydrolyzed to the acid, or reduced and hydrolyzed to the aldehyde. Joost N. H. Reek of the University of Amsterdam isomerized (ACS Catal. 2013, 3, 2939) the terminal alkene of 24 to the internal alkene, then hydroformylated that directly to give the α-methyl branched aldehyde 25.
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Taber, Douglass. "Selective Reactions of Alkenes." In Organic Synthesis. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199764549.003.0023.
Повний текст джерелаАнотація:
Fabio Doctorovich of the Universidad de Buenos Aires reported (J. Org. Chem. 2008, 73, 5379) that hydroxylamine in the presence of an Fe catalyst reduced alkenes such as 1, but not ketones or esters. Erick Carreira of ETH Zürich developed (Angew. Chem. Int. Ed. 2008, 47, 5758) mild conditions for the hydrochlorination of mono-, di- and trisubstituted alkenes. Ramgopal Bhattacharyya of Jadavpur University established (Tetrahedron Lett. 2008, 49, 6205) a simple Mo-catalyzed protocol for alkene epoxidation. Nitro alkenes are of increasing importance as acceptors for enantioselective organocatalyzed carbon-carbon bond formation. Matthias Beller of the Universität Rostock found (Adv. Synth. Cat. 2008, 350, 2493) that an alkene such as 7 was readily converted to the corresponding nitroalkene 8 by exposure to of NO gas. The reaction could also be effected with NaNO2/HOAC. Two complementary protocols for Rh-catalyzed alkene hydroformylation have been reported. Xumu Zhang of Rutgers University devised (Organic Lett. 2008, 10, 3469) a ligand system that cleanly migrated the alkene of 9, then terminally hydroformylated the resulting monosubstituted alkene, to give 10. Kian L. Tan of Boston College designed (J. Am. Chem. Soc. 2008, 130, 9210) a ligand such that the hydroformylation of the internal alkene of 11 was directed to the end of the alkene proximal to the directing OH, delivering 12. Several other methods for the functionalizing homologation of alkenes have been put forward. Chul-Ho Jun of Yonsei University assembled (J. Org. Chem. 2008, 73, 5598) a Rh catalyst that effected the oxidative acylation of a terminal alkene 13 with a primary benzylic alcohol, to give the ketone 14. For now, this approach is limited to less expensive alkenes, as the alkene, used in excess, is the reductant in the reaction. The other procedures outlined here require only stoichiometric alkene. Yasuhiro Shiraishi of Osaka University devised (Organic Lett. 2008, 10, 3117) a simple photoprocess for adding acetone to a terminal alkene 13 to give the methyl ketone 14, in what is presumably a free radical reaction.
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Taber, Douglass F. "Heteroaromatic Construction: The Fukuyama Synthesis of Tryprostatin A." In Organic Synthesis. Oxford University Press, 2013. http://dx.doi.org/10.1093/oso/9780199965724.003.0067.
Повний текст джерелаАнотація:
Alessandro Palmieri of the University of Camerino developed (Synlett 2010, 2468) the condensation of a nitro acrylate 1 with a 1,3-dicarbonyl partner 2 to give the furan 3. Chaozhong Li of the Shanghai Institute of Organic Chemistry showed (Tetrahedron Lett. 2010, 51, 3678) that an alkenyl halide 4 could be cyclized to the furan 5. Ayhan S. Demir of Middle East Technical University established (Chem. Commun. 2010, 46, 8032) that a Au catalyst could catalyze the addition of an amine 7 to a cyanoester 6 to give the pyrrole 8 . Bruce A. Arndtsen of McGill University effected (Org. Lett. 2010, 12, 4916) the net three-component coupling of an imine 9, an acid chloride 10, and an alkyne 11 to deliver the pyrrole 12. Bernard Delpech of CNRS Gif-sur-Yvette prepared (Org. Lett. 2010, 12, 4760) the pyridine 15 by combining the diene 13 with the incipient carbocation 14. Max Malacria, Vincent Gandon, and Corinne Aubert of UPMC Paris optimized (Synlett 2010, 2314) the internal Co-mediated cyclization of a nitrile alkyne 5 to the tetrasubstituted pyridine 17. Yoshiaki Nakao of Kyoto University and Tamejiro Hiyama, now at Chuo University, effected (J. Am. Chem. Soc. 2010, 132, 13666) selective substitution of a preformed pyridine 18 at the C-4 position by coupling with an alkene 19. We showed (J. Org. Chem. 2010, 75, 5737) that the anion from deprotonation of a pyridine 21 could be added in a conjugate sense to 22 to give 23. Other particularly useful strategies for further substitution of preformed pyridines have been described by Olafs Daugulis of the University of Houston (Org. Lett. 2010, 12, 4277), by Phil S. Baran of Scripps/La Jolla (J. Am. Chem. Soc. 2010, 132, 13194), and by Robert G. Bergmann of the University of California, Berkeley, and Jonathan A. Ellman of Yale University (J. Org. Chem. 2010, 75, 7863). K. C. Majumdar of the University of Kalyani developed (Tetrahedron Lett. 2010, 51, 3807) the oxidative Pd-catalyzed cylization of 24 to the indole 25. Nan Zheng of the University of Arkansas showed (Org. Lett. 2010, 12, 3736) that Fe could be used to catalyze the rearrangement of the azirine 26 to the indole 27.
Тези доповідей конференцій з теми "Selective internal oxidation"
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Devarakonda, Maruthi, Russell Tonkyn, Diana Tran, Jong Lee, and Darrell Herling. "Modeling Species Inhibition of NO Oxidation in Urea-SCR Catalysts for Diesel Engine NOx Control." In ASME 2010 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/icef2010-35054.
Повний текст джерелаАнотація:
Urea-selective catalytic reduction (SCR) catalysts are regarded as the leading NOx aftertreatment technology to meet the 2010 NOx emission standards for on-highway vehicles running on heavy-duty diesel engines. However, issues such as low NOx conversion at low temperature conditions still exist due to various factors, including incomplete urea thermolysis, inhibition of SCR reactions by hydrocarbons and H2O. We have observed a noticeable reduction in the standard SCR reaction efficiency at low temperature with increasing water content. We observed a similar effect when hydrocarbons are present in the stream. This effect is absent under fast SCR conditions where NO ∼ NO2 in the feed gas. As a first step in understanding the effects of such inhibition on SCR reaction steps, kinetic models that predict the inhibition behavior of H2O and hydrocarbons on NO oxidation are presented in the paper. A one-dimensional SCR model was developed based on conservation of species equations and was coded as a C-language S-function and implemented in Matlab/Simulink environment. NO oxidation and NO2 dissociation kinetics were defined as a function of the respective adsorbate’s storage in the SCR catalyst. The corresponding kinetic models were then validated on temperature ramp tests that showed good match with the test data.
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Luo, Zhaoyu, Parvez Sukheswalla, Scott A. Drennan, Mingjie Wang, and P. K. Senecal. "3D Numerical Simulations of Selective Catalytic Reduction of NOx With Detailed Surface Chemistry." In ASME 2017 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icef2017-3658.
Повний текст джерелаАнотація:
Environmental regulations have put stringent requirements on NOx emissions in the transportation industry, essentially requiring the use of exhaust after-treatment on diesel fueled light and heavy-duty vehicles. Urea-Water-Solution (UWS) based Selective Catalytic Reduction (SCR) for NOx is one the most widely adopted methods for achieving these NOx emissions requirements. Improved understanding and optimization of SCR after-treatment systems is therefore vital, and numerical investigations can be employed to facilitate this process. For this purpose, detailed and numerically accurate models are desired for in-cylinder combustion and exhaust after-treatment. The present paper reports on 3-D numerical modeling of the Urea-Water-Solution SCR system using Computational Fluid Dynamics (CFD). The entire process of Urea injection, evaporation, NH3 formation and NOx reduction is numerically investigated. The simulation makes use of a detailed kinetic surface chemistry mechanism to describe the catalytic reactions. A multi-component spray model is applied to account for the urea evaporation and decomposition process. The CFD approach also employs an automatic meshing technique using Adaptive Mesh Refinement (AMR) to refine the mesh in regions of high gradients. The detailed surface chemistry NOx reduction mechanism validated by Olsson et al. (2008) is applied in the SCR region. The simulations are run using both transient and steady-state CFD solvers. While transient simulations are necessary to reveal sufficient details to simulate catalytic oxidation during transient engine processes or under cyclic variations, the steady-state solver offers fast and accurate emission solutions. The simulation results are compared to available experimental data, and good agreement between experimental data and model results is observed.
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Park, Paul W., Markus Downey, David Youngren, and Claus Bruestle. "Advanced Aftertreatment System Development for a Locomotive Application." In ASME 2012 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icef2012-92198.
Повний текст джерелаАнотація:
For the first time in the locomotive industry, an advanced exhaust aftertreatment system for a locomotive application was successfully demonstrated to reduce nitrogen oxides from 6.46 g/kW·hr to 1.21g/kWhr to meet the needs of local NOx reduction requirements for non-attainment areas. Five 2,240 kW (3,005 horsepower) PR30C line-haul repowered Progress Rail locomotives were equipped with diesel oxidation catalyst and selective catalytic reduction technologies to accumulate more than 27,000 hours in total in revenue service. Full emissions performance including carbon monoxide, hydrocarbons, nitrogen oxides and particulate matter was conducted at Southwest Research Institute on a regular basis to measure the change of emissions performance for two selected locomotives. The emissions performance of the aftertreatment system did not show any degradation during 3,000 hours operation. After 3,000 hours operation, 0.13 g/kW·hr carbon monoxide (89–91% reduction), 0.027 g/ kW·hr hydrocarbons (91% reduction), 1.08–1.21 g/ kW·hr nitrogen oxides (81–83% reduction) and 0.05–0.08 g/ kW·hr particulate matter (38–58% reduction) were measured on the line-haul cycle. The baseline emissions levels of the engine are within Tier 2 EPA locomotive limits. The newly developed close loop control software successfully controlled targeted nitrogen oxides reduction with minimum ammonia slip during the locomotive emission cycle tests.
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Osborne, Dustin T., Doug Biagini, Harold Holmes, Steven G. Fritz, Michael Jaczola, and Michael E. Iden. "PR30C-LE Locomotive With DOC and Urea Based SCR: Baseline and Initial Aftertreatment Emissions Testing." In ASME 2012 Internal Combustion Engine Division Spring Technical Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ices2012-81157.
Повний текст джерелаАнотація:
The PR30C-LE is a repowered six-axle, 2,240 kW (3,005 hp), line-haul locomotive that was introduced to the rail industry in 2009. The Caterpillar 3516C-HD Tier 2 engine is equipped with an exhaust aftertreatment module containing selective catalyst reduction (SCR) and diesel oxidation catalyst (DOC) technology. PR30C-LE exhaust emission testing was performed on test locomotive PRLX3004. Phase-1 of the test program included the following tasks: engine-out baseline emissions testing without the aftertreatment module installed, aftertreatment module installation, commissioning and degreening, and emissions testing with the aftertreatment. Emission results from testing without the aftertreatment module, referred to as the baseline configuration, indicated that PRLX3004 emissions were below Tier 2 EPA locomotive limits without aftertreatment. Emission test results with the DOC and SCR aftertreatment module showed a reduction in nitrogen oxides (NOx) of 80 percent over the line-haul cycle, and 59 percent over the switcher cycle. Particulate matter (PM) was reduced by 43 percent over the line-haul cycle and 64 percent over the switcher cycle. Line-haul cycle composite emissions of Hydrocarbon (HC) and carbon monoxide (CO) were reduced by 93 and 72 percent, respectively. The PR30C-LE locomotive achieved Tier 4 line-haul NOx, CO, HC, as well as Tier 3 PM levels. There are currently five PR30C-LE locomotives in operation in California and Arizona, and the total hour accumulation of the five PR30C-LE locomotives as of October 2011 was 20,000 hours.
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Aguilar, Jonathan, Leslie Bromberg, Alexander Sappok, Paul Ragaller, Jean Atehortua, and Xiaojin Liu. "Catalyst Ammonia Storage Measurements Using Radio Frequency Sensing." In ASME 2017 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icef2017-3572.
Повний текст джерелаАнотація:
Motivated by increasingly strict NOx limits, engine manufactures have adopted selective catalytic reduction (SCR) technology to reduce engine-out NOx below mandated levels. In the SCR process, nitrogen oxides (NOx) react with ammonia (NH3) to form nitrogen and water vapor. The reaction is influenced by several variables, including stored ammonia on the catalyst, exhaust gas composition, and catalyst temperature. Currently, measurements from NOx and/or NH3 sensors upstream and downstream of the SCR are used with predictive models to estimate ammonia storage levels on the catalyst and control urea dosing. This study investigated a radio frequency (RF) -based method to directly monitor the ammonia storage state of the SCR catalyst. This approach utilizes the SCR catalyst as a cavity resonator, in which an RF antenna excites electromagnetic waves within the cavity to monitor changes in the catalyst state. A mmonia storage causes changes in the dielectric properties of the catalyst, which directly impacts the RF signal. Changes in the RF signal relative to stored a mmonia (NH3) were evaluated over a wide frequency range as well as temperature and exhaust conditions. The RF response to NH3 storage, desorption, and oxidation on the SCR was observed to be well-correlated with changes in the catalyst state. Calibrated RF measurements demonstrate the ability to monitor the adsorption state of the SCR to within 10 % of the sensor full scale. The results indicate direct measurement of SCR ammonia storage levels, and resulting catalyst feedback control, via RF sensing to have significant potential for optimizing the SCR system to improve NOx conversion and decrease urea consumption.
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Downey, Markus, and Ulrich Pfahl. "Advanced Metal Substrate Technology for Large Engine Exhaust Gas Aftertreatment Systems." In ASME 2011 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/icef2011-60096.
Повний текст джерелаАнотація:
In the coming years non-road and locomotive diesel engine exhaust gas emissions will become regulated by EPA Tier4 legislation. The stringent emission limits of Tier 4 will require the use of aftertreatment technology currently being used in on-road applications. Based on the potentially large displacements of these engines, the aftertreatment systems will be large and expensive. The flow restriction that is added by the aftertreatment system will result in additional engine pumping work and lower fuel efficiency. The high durability requirements that are demanded of the aftertreatment systems is another factor that needs to be considered. Technologies that reduce complexity, size and cost of the aftertreatment system and minimize incremental fuel consumption are needed. Metal substrate technology offers a number of solutions for the challenges in meeting Tier 4 legislation. The substrates can be used for oxidation catalysts, selective catalytic reduction and slip catalysts depending on what kind of coating is applied to them. The thin wall technology that metal substrates can offer, even at coarse cell densities and lack of required retention mat for system integration provides more open frontal area, leading to lower flow restriction and lower fuel consumption. When designing a modular exhaust system, the shape flexibility will allow for denser packaging of the catalysts. This maximizes the amount of available cross-sectional area, leading to a most compact exhaust system and again better fuel efficiency. Large diameter catalysts can be manufactured in one piece, rather than being joined together from several pieces. A more robust substrate is the outcome.
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Kwon, Sangil, Sung-Woo Kim, Ki-Ho Kim, Youngho Seo, Mun Soo Chon, Daesik Kim, Sungwook Park, Hyun Gu Roh, Hyun Kyu Suh, and Suhan Park. "Exhaust Emission Characteristics of Excavator With 6.0 Liter Diesel Engine in Real Work Conditions." In ASME 2018 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icef2018-9777.
Повний текст джерелаАнотація:
The purpose of this study is evaluate emission characteristics, such as nitrogen oxides (NOx), hydrocarbon, carbon monoxide, and particulate matter (PM), of excavator with Tier-4f level diesel engine in the real work conditions. The test excavator has an engine power of 124 kW at an engine speed of 1800rpm, and it has various after-treatment devices, such as exhaust gas recirculation (EGR), selective catalytic reduction (SCR), and diesel oxidation catalyst (DOC), to reduce the engine-out emissions. The emissions including carbon monoxide (CO), carbon dioxides (CO2), and NOx, were measured by portable emission measurement system (PEMS). The PEMS device conducted a correlation analysis with the emission bench on the engine dynamometer before being used to measure the real-work to confirm the reliability of the equipment. The tests were carried out in four categories: idling, driving, excavations and flattening. It revealed that the average power output for each operation mode was higher in the order of flattening, excavation, and drive. On average, those are higher than that for the non-road transient cycle (NRTC) certification mode as 1.5 to 1.9 times. It may be determined that the power output is higher in conditions where there are more boom and bucket movements than the movement of the vehicle itself. In emission analysis, NOx and HC emission in driving mode are higher than other two modes: excavation and flattening. The real time NOx have been low in most test conditions, but large quantities of NOx have been released due to the deactivation of the SCR catalyst during cold start period or immediately after the non-working.
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Osborne, Dustin T., Doug Biagini, Harold Holmes, Steven G. Fritz, Michael Jaczola, and Michael E. Iden. "PR30C-LE Locomotive With DOC and Urea Based SCR: Field Trial and Emissions Testing After 1,500 and 3,000 Hours of Operation." In ASME 2012 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icef2012-92014.
Повний текст джерелаАнотація:
This paper details part two of the demonstration of a 2,240 kW (3,005 HP) PR30C-LE locomotive with exhaust aftertreatment containing diesel oxidation catalysts (DOC) and urea-based selective catalytic reduction (SCR). The PR30C-LE is a remanufactured and repowered, six-axle, diesel-electric, line-haul locomotive. Program objectives were to measure emission levels of the locomotive and record locomotive and aftertreatment operations during a 12 month revenue service field trial. Phase 1 of the program involved engine baseline emissions testing as well as emissions testing with the aftertreatment at the beginning of its useful life, or the 0-hour condition. Results from Phase 1 showed engine-out emission levels were within U.S. EPA Locomotive Tier 2 limits. With aftertreatment at beginning of useful life, hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) were below Tier 4 limits, and particulate matter (PM) was below Tier 3 limits. Phase 2 consisted of a 12 month revenue service field trial and additional emissions testing completed at the midpoint and end of the field trial. On-board GPS data, aftertreatment NOx sensor data, and various locomotive operating parameters were logged continuously during the field trial. The field trial data suggests the impact SCR technology has on locomotive NOx emissions is driven primarily by locomotive utilization and loading factor. Overall the field trial included 3,082 hours of operation and PRLX3004 generated approximately 572 MW-hours of work over the 12 month period. Emission test results at the 1,500-hour and 3,000-hour conditions showed very little change from 0-hour test results. Emission levels remained below Tier 4 limits for HC, CO, and NOx, and below the Tier 3 limit for PM. Phase 2 test results suggest there was no significant degradation in emissions performance during the field trial, and no major issues with the locomotive and aftertreatment were detected. In total there are currently five PR30C-LE locomotives in operation within California and Arizona. Together they have completed a cumulative 30,800 hours of revenue service through June 2012 without report of a major issue.
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Mulone, V., A. Cozzolini, P. Abeyratne, D. Littera, M. Thiagarajan, M. C. Besch, and M. Gautam. "Soot Modeling for Advanced Control of Diesel Engine Aftertreatment." In ASME 2010 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/icef2010-35160.
Повний текст джерелаАнотація:
Diesel Particulate Filters (DPFs) are well assessed aftertreatment devices, equipping almost every modern diesel engine on the market to comply with today’s stringent emission standards. However, an accurate estimation of soot loading, which is instrumental to ensuring optimal performance of the whole engine-after-treatment assembly is still a major challenge. In fact, several highly coupled physical-chemical phenomena occur at the same time, and a vast number of engine and exhaust dependent parameters make this task even more daunting. This challenge may be solved with models characterized by different degrees of detail (0-D to 3-D) depending on the specific application. However, the use of real-time, but accurate enough models, may be of primary importance to face with advanced control challenges, such as the integration of the DPF with the engine or other critical aftertreatment components (Selective Catalytic Reduction (SCR) or other NOx control components), or to properly develop model-based OBD sensors. This paper aims at addressing real time DPF modeling issues with special regard to key parameter settings, by using the 1D code ExhAUST (Exhaust Aftertreatment Unified Simulation Tool), developed jointly by the University of Rome Tor Vergata and West Virginia University. ExhAUST is characterized by a novel and unique full analytical treatment of the wall that allows faithful representation with high degree of detail the evolution of soot loading inside the porous matrix. Numerical results are compared with experimental data gathered at West Virginia University (WVU) engine laboratory using a Mack heavy-duty diesel engine coupled to a Johnson Matthey CCRT (DOC, Diesel Oxidation Catalyst+CDPF, Catalyzed DPF) aftertreatment system. To that aim, the engine test bench has been equipped with a DPF weighing setup to track soot load over a specifically developed engine operating procedure. Obtained results indicate that the model is accurate enough to capture soot loading and back pressure histories with regard to different steady state engine operating points, without needing any tuning procedure of the key parameters. Thus, the use of ExhAUST for application to advanced after-treatment control appears promising at this stage.
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Cheenkachorn, Kraipat, Wallis A. Lloyd, and Joseph M. Perez. "Use of Pressurized Differential Scanning Calorimetry (PDSC) to Evaluate Effectiveness of Additives in Vegetable Oil Lubricants." In ASME 2003 Internal Combustion Engine Division Spring Technical Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/ices2003-0657.
Повний текст джерелаАнотація:
Use of renewable resources to replace petroleum base stocks in lubricants is attractive. Research on additives enhanced by current advances in genetic and chemical modifications has resulted in improved oxidative stability of vegetable oils. Like most oxidation processes, the oxidative degradation of vegetable oils is complex. The auto-oxidation free radical mechanisms and hydroperoxide theories of oxidation have been well studied. Factors that influence the degradation of oils include temperature, surface reactivity, rates of formation of radicals, chemical composition factors such as olefin and aromatic content and additive effectiveness. This uses pressurized differential scanning calorimetry to evaluate the oxidative stability of four biodegradable fluids with and without additives. The oleic acid content of the four fluids ranged from 83 to 23 percent. Reaction kinetics are used to explain observed differences in phase transformation and polymerization reactions. Additive selection to obtain maximum effectiveness in the base stocks is reported.