Academic literature on the topic 'Ring catalog'
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Journal articles on the topic "Ring catalog"
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Madore, Barry F., Erica Nelson, and Kristen Petrillo. "ATLAS AND CATALOG OF COLLISIONAL RING GALAXIES." Astrophysical Journal Supplement Series 181, no. 2 (2009): 572–604. http://dx.doi.org/10.1088/0067-0049/181/2/572.
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Mizuno, D. R., K. E. Kraemer, N. Flagey, et al. "A CATALOG OF MIPSGAL DISK AND RING SOURCES." Astronomical Journal 139, no. 4 (2010): 1542–52. http://dx.doi.org/10.1088/0004-6256/139/4/1542.
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Wakamatsu, K., M. Hamabe, M. T. Nishida, and A. Tomita. "A Nuclear Ring in the Sa(r!) Galaxy NGC 7742." International Astronomical Union Colloquium 157 (1996): 83–85. http://dx.doi.org/10.1017/s0252921100049460.
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NGC 7742 is well known for its prominent blue nuclear ring around an EO-like core, and so appears as a Hoag-type galaxy, an elliptical galaxy with an outer ring (Schweizer et al. 1987). The galaxy is classified as Sa(r!) in the Revised Shapley-Ames Catalog (Sandage and Tammann 1987) with an exclamation mark to emphasize the prominence of the ring. Its photographs are published in Laustsen et al. (1987), Wray (1988), and Sandage & Bedke (1994).The ring has a diameter of 19″ = 1.6 kpc at a distance of 17.1 Mpc (Buta & Crocker 1993), and so should be a nuclear ring of the galaxy. Nuclear rings and pseudorings are often detected in strongly barred (SB) galaxies, and interpreted to be linked to the inner Lindblad resonance (Buta & Crocker 1993). These nuclear features are, however, also found in some weakly-barred (SAB) and non-barred (SA) galaxies. NGC 7742 is a galaxy of the highest circular symmetry in its core, ring, and main body, and so the best object for a detailed study of formation mechanisms of nuclear rings in non-barred galaxies.
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Timmis, Ian, and Lior Shamir. "A Catalog of Automatically Detected Ring Galaxy Candidates in PanSTARRS." Astrophysical Journal Supplement Series 231, no. 1 (2017): 2. http://dx.doi.org/10.3847/1538-4365/aa78a3.
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Parlea, Lorena, Eckart Bindewald, Rishabh Sharan, et al. "Ring Catalog: A resource for designing self-assembling RNA nanostructures." Methods 103 (July 2016): 128–37. http://dx.doi.org/10.1016/j.ymeth.2016.04.016.
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Crocker, Deborah A., Pamela D. Baugus, and R. Buta. "HII Regions in Resonance-Ring Spiral Galaxies." International Astronomical Union Colloquium 157 (1996): 80–82. http://dx.doi.org/10.1017/s0252921100049459.
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Resonance ring galaxies are barred (and sometimes nonbarred) spiral galaxies which display an inner, outer, or nuclear ring in the light distribution. This study is of the HII region properties in 32 probable resonance ring galaxies selected mainly from the Catalog of Southern Ringed Galaxies (CSRG; Buta 1995). The objective of the study is to illustrate the distributions of HII regions in classic examples of ringed galaxies, and to relate the observed properties to resonance theory. Here we present a brief summary of a more extensive paper on the results of this study (Crocker, Baugus, & Buta 1996).
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Fernandez, Julia, Sol Alonso, Valeria Mesa, Fernanda Duplancic, and Georgina Coldwell. "Properties of galaxies with ring structures." Astronomy & Astrophysics 653 (September 2021): A71. http://dx.doi.org/10.1051/0004-6361/202141208.
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Aims. We present a statistical analysis of different characteristics of ringed spiral galaxies with the aim of assessing the effects of rings on disk galaxy properties. Methods. We built a catalog of ringed galaxies from the Sloan Digital Sky Survey Data Release 14 (SDSS-DR14). Via visual inspection of SDSS images, we classified the face-on spiral galaxies brighter than g < 16.0 mag into galaxies with: an inner ring, an outer ring, a nuclear ring, both an inner and an outer ring, and a pseudo-ring. In addition to rings, we recorded morphological types and the existence of bars, lenses, and galaxy pair companions with or without interaction. With the goal of providing an appropriate quantification of the influence of rings on galaxy properties, we also constructed a suitable control sample of non-ringed galaxies with similar redshift, magnitude, morphology, and local density environment distributions to those of ringed ones. Results. We found 1868 ringed galaxies, accounting for 22% of the full sample of spiral galaxies. In addition, within galaxies with ringed structures, 46% have an inner ring, 10% an outer ring, 20% both an inner and an outer ring, 6% a nuclear ring, and 18% a partial ring. Moreover, 64% of the ringed galaxies present bars. We also found that ringed galaxies have both a lower efficiency of star formation activity and older stellar populations (as derived with the Dn(4000) spectral index) with respect to non-ringed disk objects from the control sample. Moreover, there is a significant excess of ringed galaxies with red colors. These effects are more important for ringed galaxies that have inner rings and bars with respect to their counterparts that have some other types of rings and are non-barred. The color-magnitude and color-color diagrams show that ringed galaxies are mostly concentrated in the red region, while non-ringed spiral objects are more extended to the blue zone. Galaxies with ringed structures present an excess of high metallicity values compared to non-ringed ones, which show a 12 + Log(O/H) distribution toward lower values. These findings seem to indicate that rings are peculiar structures that produce an accelerating galactic evolution, strongly altering the physical properties of their host galaxies.
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Buta, Ronald. "The Morphology of Barred Galaxies." International Astronomical Union Colloquium 157 (1996): 11–22. http://dx.doi.org/10.1017/s0252921100049368.
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AbstractIn this review, the morphology of barred galaxies at optical wavelengths is discussed, focussing mainly on early to intermediate revised Hubble types in the range S0+ to Sbc. Previous work by Hubble, Sandage, de Vaucouleurs, Vorontsov-Velyaminov, and Kormendy is described. The primary emphasis is on ring phenomena, and morphological results from the Catalog of Southern Ringed Galaxies are summarized.
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Lomnitz, Cinna. "Search of a worldwide catalog for earthquakes triggered at intermediate distances." Bulletin of the Seismological Society of America 86, no. 2 (1996): 293–98. http://dx.doi.org/10.1785/bssa0860020293.
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Abstract An anomalous increase of seismicity was recorded at intermediate distances from the Landers, California, earthquake of 28 June 1992 (M = 7.3). Several authors have suggested that enhanced activity was triggered at distances of up to 17 fault lengths. We test a 90-year catalog of shallow world earthquakes (M &gt; 7) for evidence of this effect. It is found that triggering is present even at these high magnitude levels. The pattern of enhanced activity comprises two concentric regions: (a) the aftershock region and (b) the region of triggered seismicity at distances of 300 to 1000 km. The two regions are activated together; they are separated by a ring-shaped gap at a distance of around 300 km. This “Mexican Hat” pattern is attributed to recovery flows generated by the stress drop of the earthquake in a steady-state convecting system.
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Mendoza, Blanca, Ernesto Jáuregui, Rosa Diaz-Sandoval, Virginia García-Acosta, Victor Velasco, and Guadalupe Cordero. "Historical Droughts in Central Mexico and Their Relation with El Niño." Journal of Applied Meteorology 44, no. 5 (2005): 709–16. http://dx.doi.org/10.1175/jam2210.1.
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Abstract A catalog containing an unprecedented amount of historical data in central Mexico, covering almost six centuries (1450–1900), is used. This is a catalog of agricultural disasters that includes events associated with hydrometeorological phenomena, or hazards, whose effects were mainly felt in the agricultural sector, such as droughts. An analysis of the historical series of droughts in central Mexico for the period of 1450–1900 is performed. Periods of frequent drought centered at the years 1483, 1533, 1571, 1601, 1650, 1691, 1730, 1783, 1818, and 1860 have been identified. In particular, droughts in Mexico City and northwest Mexico that were identified through poor tree-ring growth are included in the frequent drought periods obtained in this work. Moreover, it was found that droughts occurred in El Niño years mainly for events of very strong and strong strengths, at a significant level. Also, most droughts lasted for 1 or 2 yr. Last, by analyzing the periodicities of the drought time series it was found that those that are the most conspicuous are the quasi-bidecadal frequencies of 18.9 and 21 yr.
Dissertations / Theses on the topic "Ring catalog"
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Petrillo, Kristen. "A study of interacanding and companion galaxies: implications for cosmology." Pomona College, 2008. http://ccdl.libraries.claremont.edu/u?/stc,47.
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This paper examined a few different types of interacting galaxies and the implications the data has on cosmological theories. An analysis of the Holmberg Effect, Holmberg (1969)’s observation that companion galaxies tend to be near the poles of edge-on galaxies rather than in the planes, was done by reexamining the spirals viewed by Holmberg. Only using radial velocity confirmed companions to test for this effect showed that if anything, the opposite of the Holmberg effect is true. However, due to small number statistics, more edge-on spirals and their companions would have to be viewed in order to determine if this is an actual physical effect of anisotropic companion distribution around primary galaxies. It is important to discover if there is a preferred distribution, because it could point to the distribution of dark matter around the primary galaxies, and have interesting impacts on large-scale universal structure and cosmology theory.
Books on the topic "Ring catalog"
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Overstreet, Robert M. The Overstreet toy ring price guide. 3rd ed. Gemstome Pub., 1997.
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Overstreet, Robert M. The Overstreet premium ring price guide. R.M. Overstreet, 1994.
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Ingried, Brugger, Benesch Evelyn, Kunstforum Wien, and Museum Würth, eds. Attersee: Die Liebe, das Haus, der Ring. Hatje Cantz, 2005.
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Attersee, Christian Ludwig. Attersee: One love--one house--one ring. Hatje Cantz, 2006.
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Attersee, Christian Ludwig. Attersee: One love - one house - one ring. Hatje Cantz, 2006.
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Ornament and amulet: Rings of the Islamic lands. Nour Foundation in association with Azimuth Editions and Oxford University Press, 1993.
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Hammervold, Alf. Dactyliotheca Norvegica medioevalis: Fingerringer fra middelalderen i Norge : en undersøkelse av fingerringer fra middelalderen og ringer av middelaldertype. Universitets oldsaksamling, Institutt for arkeologi, kunsthistorie og numismatikk, Universitetet i Oslo, 1997.
Find full textBook chapters on the topic "Ring catalog"
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Taber, Douglass F. "Metal-Mediated C–C Ring Construction: (+)-Shiromool (Baran)." In Organic Synthesis. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190200794.003.0076.
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Seiji Iwasa of the Toyohashi University of Technology devised (Adv. Synth. Catal. 2012, 354, 3435) a water-soluble Ru catalyst for enantioselective intramolecular cyclopropanation that could be separated from the product and recycled by simple water/ether extraction. Minoru Isobe of the National Tsing Hua University combined (Org. Lett. 2012, 14, 5274) the Nicholas and Hosomi-Sakurai reactions to close the cyclobutane ring of 4. Kazunori Koide of the University of Pittsburgh established (Tetrahedron Lett. 2012, 53, 6637) that the activity of a Ru metathesis catalyst, shut down by the presence of TBAF, could be restored by the inclusion of TMS2O. Jan Streuff of Albert-Ludwigs-Universität Freiburg demonstrated (Angew. Chem. Int. Ed. 2012, 51, 8661) that the enantiomerically pure Brintzinger complex mediated the reductive cyclization of 7 to 8. Huw M.L. Davies of Emory University prepared (J. Am. Chem. Soc. 2012, 134, 18241) the cyclopentenone 11 by the Rh-mediated addition of 10 to 9 followed by elimination. Christophe Meyer and Janine Cossy of ESPCI ParisTech showed (Angew. Chem. Int. Ed. 2012, 51, 11540) that the Rh-mediated rearrangement of 12 to 13 proceeded with substantial diastereocontrol. Jian-Hua Xie and Qi-Lin Zhou of Nankai University observed (Org. Lett. 2012, 14, 6158) that the enantioselective hydrogenation of 14 followed by Claisen rearrangement established the cyclic quaternary center of 17 with high stereocontrol. Ken Tanaka of the Tokyo University of Agriculture and Technology devised (Angew. Chem. Int. Ed. 2012, 51, 13031) the Rh-mediated addition of the enyne 18 to 19 to give the highly substituted cyclohexene 20. Daesung Lee of the University of Illinois at Chicago showed (Chem. Sci. 2012, 3, 3296) that the ring-opening/ring-closing metathesis of 21 delivered 22 with high diastereocontrol. Andreas Speicher of Saarland University cyclized (Org. Lett. 2012, 14, 4548) 23 to 24 with significant atropisomeric induction. Erick M. Carreira of the Eidgenössische Technische Hochschule Zürich effected (J. Am. Chem. Soc. 2012, 134, 20276) the polycyclization of racemic 25 to 26 with high enantiomeric excess. Medium rings are often the most difficult to construct, because of the inherent congestion across the forming ring. Phil S. Baran of Scripps/La Jolla effected (Angew. Chem. Int. Ed. 2012, 51, 11491) the cyclization of 27 to 28 as a single dominant diastereomer.
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Taber, Douglass F. "C–N Ring Construction: The Harrity Synthesis of Quinolizidine (–)-217A." In Organic Synthesis. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190200794.003.0054.
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David M. Jenkins of the University of Tennessee devised (J. Am. Chem. Soc. 2011, 133, 19342) an iron catalyst for the aziridination of an alkene 1 with an aryl azide 2. Yoshiji Takemoto of Kyoto University cyclized (Org. Lett. 2011, 13, 6374) the prochiral oxime derivative 4 to the azirine 5 in high ee. Organometallics added to 5 syn to the pendant ester. Hyeung-geun Park of Seoul National University used (Adv. Synth. Catal. 2011, 353, 3313) a chiral phase transfer catalyst to effect the enantioselective alkylation of 6 to 7. Yian Shi of Colorado State University showed (Org. Lett. 2011, 13, 6350) that a chiral Brønsted acid mediated the enantioselective cyclization of 8 to 9. Mattie S.M. Timmer of Victoria University of Wellington and Bridget L. Stocker of Malaghan Institute of Medical Research effected (J. Org. Chem. 2011, 76, 9611) the oxidative cyclization of 10 to 11. They also showed (Tetrahedron Lett. 2011, 52, 4803, not illustrated) that the same cyclization worked well to construct piperidine derivatives. Jose L. Vicario of the Universidad del País Vasco extended (Adv. Synth. Catal. 2011, 353, 3307) organocatalysis to the condensation of 12 with 13 to give the pyrrolidine 14. Jinxing Ye of the East China University of Science and Technology used (Adv. Synth. Catal. 2011, 353, 343) the same Hayashi catalyst to condense 15 with 16 to give 17. André B. Charette of the Université de Montreal expanded (Org. Lett. 2011, 13, 3830) 18, prepared by Petasis-Mannich coupling followed by ring-closing metathesis, to the piperidine 20. Marco Bella of the “Sapienza” University of Roma effected (Org. Lett. 2011, 13, 4546) enantioselective addition of 22 to the prochiral 21 to give 23. Ying-Chun Chen of Sichuan University and Chun-An Fan of Lanzhou University cyclized (Adv. Synth. Catal. 2011, 353, 2721) 24 to 25 in high ee. Andreas Schmid of TU Dortmund showed (Adv. Synth. Catal. 2011, 353, 2501) that ω-laurolactam hydrolases could be used to cyclize the ester 26, but not the free acid, to the macrolactam 27.
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Taber, Douglass F. "Organocatalytic C–C Ring Construction: Prostaglandin F2α (Aggarwal)." In Organic Synthesis. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190200794.003.0072.
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Marco Lombardo of the Università degli Studi di Bologna devised (Adv. Synth. Catal. 2012, 354, 3428) a silyl-bridged hydroxyproline catalyst that mediated the enantioselective addition of 2 to cinnamaldehyde 1 to give 3. Yoann Coquerel and Jean Rodriguez of Aix Marseille Université showed (Adv. Synth. Catal. 2012, 354, 3523) that a hybrid epi-cinchonine catalyst directed the enantioselective and diastereoselective addition of the amide 4 to the nitro alkene 5 to give 6. Magnus Rueping of RWTH Aachen observed (Angew. Chem. Int. Ed. 2012, 51, 12864) that a chiral Brønsted acid mediated the diastereoselective and enantioselective formation of 9 by the addition of 8 to cyclopentadiene 7. Marco Bandini, also of the University of Bologna, combined (Chem. Sci. 2012, 3, 2859) organocatalysis with gold catalysis to effect the cyclization of 10 to 11. Min Shi of the Shanghai Institute of Organic Chemistry prepared (Chem. Commun. 2012, 48, 2764) the quaternary cyclic amino acid derivative 14 by adding 13 to the acceptor 12. Makoto Tokunaga of Kyushu University prepared (Org. Lett. 2012, 14, 6178) the ketone 17 by the hydrolytic enantioselective protonation of the enol ester 15. Hiyoshizo Kotsuki of Kochi University developed (Synlett 2012, 23, 2554) a dual catalyst combination that effectively mediated the enantioselective addition of malonate even to the congested acceptor 18. Yoshitaka Hamashima and Toshiyuki Kan of the University of Shizuoka established (Org. Lett. 2012, 14, 6016) a protocol for the enantioselective brominative cyclization of 21, readily available by the reductive alkylation of benzoic acid. Polycarbocyclic ring systems can also be prepared by organocatalysis. Ying-Chun Chen of Sichuan University tuned (J. Am. Chem. Soc. 2012, 134, 19942) cinchona-derived catalysts to selectively convert 23 into either exo (illustrated) or endo 25. Peng-Fei Xu of Lanzhou University developed (Angew. Chem. Int. Ed. 2012, 51, 12339) a supramolecular iminium catalyst for the intramolecular Diels-Alder cycloaddition of 26. In a spectacular illustration of the power of organocatalysis, Varinder K. Aggarwal of the University of Bristol dimerized (Nature 2012, 489, 278) succinaldehyde from the hydrolysis of commercial 28 directly to the unsaturated aldehyde 29. Diastereoselective conjugate addition led to prostaglandin F2α 30.
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Taber, Douglass F. "Carbocyclic Ring Construction: The Nicolaou Synthesis of Myceliothermophin E." In Organic Synthesis. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190646165.003.0082.
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Nan Zheng of the University of Arkansas developed (Adv. Synth. Catal. 2014, 356, 2831) a Ru catalyst for the addition of an amino cyclopropane 1 to an alkyne 2 to give 3. The reaction proceeded with high regiocontrol, but only modest stereocontrol. Alain De Mesmaeker of Syngenta Crop Protection, Switzerland found (Tetrahedron Lett. 2014, 55, 6577) that the β,γ-unsaturated amide 4 worked particularly well as a precursor to the keteniminium that cyclized to give, after hydrolysis, the cyclobutanone 5. Baeyer–Villiger oxidation of 5 led to 5-deoxystrigol 6. David Tymann and Martin Hiersemann of the Technische Universität Dortmund have been exploring (Org. Lett. 2014, 16, 4062; Synthesis 2014, 46, 3110) the intramolecular carbonyl ene reaction as a tool for the assembly of highly substituted cyclopentanes, as in the conversion of 7 to 8. On oxidation, 8 was readily carried on to the alkene 9. James L. Leighton of Columbia University conceived (J. Am. Chem. Soc. 2014, 136, 9878) the cascade transformation of 10 to 12. Deprotonation/silylation set the stage for Claisen rearrangement to give 11. The subsequent Cope rearrangement is an equilibrium process, driven by the ring strain of 11. K. C. Nicolaou of Rice University described (Angew. Chem. Int. Ed. 2014, 53, 10970) the total synthesis of the cytotoxic tetramic acid derivative myceliothermophin E 15. A key step in the synthesis was the intramolecular Michael addition/ aldol condensation that converted 13 to 14.
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Taber, Douglass F. "C–N Ring Construction: The Fujii/Ohno Synthesis of (–)-Quinocarcin." In Organic Synthesis. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190200794.003.0056.
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Tsutomu Katsuki of Kyushu University devised (Org. Lett. 2012, 14, 4658) a Ru catalyst for the enantioselective aziridination of vinyl ketones such as 1. David W.C. MacMillan of Princeton University added (J. Am. Chem. Soc. 2012, 134, 11400) 3 to the alkene 4 under single electron conditions to give 5 with high stereocontrol. Barry M. Trost of Stanford University effected (J. Am. Chem. Soc. 2012, 134, 4941) the Pd-catalyzed addition of 7 to an imine 6 to give the pyrrolidine 8. More recently, he used (J. Am. Chem. Soc. 2013, 135, 2459) this approach to construct pyrrolidines containing defined quaternary centers. Christoph Schneider of the Universität Liepzig employed (Org. Lett. 2012, 14, 5972) an organocatalyst to control the relative and absolute configuration not only of the nitrogen-containing ring, but also of the stereogenic center on the sidechain of the pyrrolidone 11. Wei Wang of Lanzhou University also used (Adv. Synth. Catal. 2012, 354, 2635) an organocatalyst to assemble the pyrrolidine 14bearing two stereogenic centers. Using a gold catalyst, Constantin Czekelius of the Freie Universität Berlin constructed (Angew. Chem. Int. Ed. 2012, 51, 11149) the pyrrolidine 16 having a defined quaternary center. Motomu Kanai of the University of Tokyo used (J. Am. Chem. Soc. 2012, 134, 17019) a Cu catalyst to prepare both pyrrolidines and piperidines by condensing the precursor protected aminal 17 with a ketone 18. Wolfgang Kroutil of the University of Graz effected (Angew. Chem. Int. Ed. 2012, 51, 6713) selective enzymatic reductive amination of the methyl ketone of 20 to give, after cyclization and hydrogenation, the 2,6-dialkyl piperidine 21. Ramakrishna G. Bhat of the Indian Institute of Science Education and Research showed (J. Org. Chem. 2012, 77, 11349) that the reductive cyclization of the amino acid derivative could proceed with high diastereoselectivity to give 23. Peter O’Brien of the University of York and Iain Coldham of the University of Sheffield prepared (J. Am. Chem. Soc. 2012, 134, 5300) both pyrrolidines and piperidines by metalation of an aryl derivative such as 24, followed by alkylation. Shital K. Chattopadhyay of the University of Kalyani cyclized (J. Org. Chem. 2012, 77, 11056) the nitrone 26 to 27 with high diastereoselectivity.
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Taber, Douglass F. "C–N Ring Construction: The Waser Synthesis of Jerantinine E." In Organic Synthesis. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190646165.003.0053.
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James A. Bull of Imperial College London prepared (J. Org. Chem. 2013, 78, 6632) the aziridine 2 with high diastereocontrol by adding the anion of diiodomethane to the imine 1. Karl Anker Jørgensen of Aarhus University observed (Chem. Commun. 2013, 49, 6382) high ee in the distal aziridination of 3 to give 4. Benito Alcaide of the Universidad Complutense de Madrid and Pedro Almendros of ICOQ- CSIC Madrid reduced (Adv. Synth. Catal. 2013, 355, 2089) the β-lactam 5 to the azetidine 6. Hiroaki Sasai of Osaka University added (Org. Lett. 2013, 15, 4142) the allenoate 8 to the imine 7, delivering the azetidine 9 in high ee. Tamio Hayashi of Kyoto University, the National University of Singapore, and A*STAR devised (J. Am. Chem. Soc. 2013, 135, 10990) a Pd catalyst for the enantioselective addition of the areneboronic acid 11 to the pyrroline 10 to give 12. Ryan A. Brawn of Pfizer (Org. Lett. 2013, 15, 3424) reported related results. Nicolai Cramer of the Ecole Polytechnique Fédérale de Lausanne developed (J. Am. Chem. Soc. 2013, 135, 11772) a Ni catalyst for the cyclization of the formamide 13 to the lactam 14. Andrew D. Smith of the University of St. Andrews used (Org. Lett. 2013, 15, 3472) an organocatalyst to cyclize 15 to 16. Jose L. Vicario of the Universidad del Pais Vasco effected (Synthesis 2013, 45, 2669) the multicomponent coupling of 17, 18, and 19, mediated by an organocatalyst, to construct 20 in high ee. André Beauchemin of the University of Ottawa explored (J. Org. Chem. 2013, 78, 12735) the thermal cyclization of ω-alkenyl hydroxyl amines such as 21. Abigail G. Doyle of Princeton University developed (Angew. Chem. Int. Ed. 2013, 52, 9153) a Ni catalyst for the enantioselective addition of aryl zinc bromides such as 24 to the prochiral 23, to give 25 in high ee. Dennis G. Hall of the University of Alberta developed (Angew. Chem. Int. Ed. 2013, 52, 8069) an in situ preparation of the allyl boronate 26 in high ee. Addition to the aldehyde 27 proceeded with high diasteroselectivity.
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Taber, Douglass F. "Organocatalyzed C–C Ring Construction: The Jørgenson Synthesis of (+)-Estrone." In Organic Synthesis. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190646165.003.0070.
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Ana Maria Faísca Phillips and Maria Teresa Barros of the Universidade Nova de Lisboa added (Eur. J. Org. Chem. 2014, 152) the bromo ester 1 to cinnamaldehyde 2 to give the cyclopropyl phosphonate 3 in high ee. Mukund P. Sibi and Jayaraman Sivaguru of North Dakota State University used (Angew. Chem. Int. Ed. 2014, 53, 5604) an organocatalyst to mediate the 2+2 photocycloaddition of 4, leading to 5. Shu-Li You of the Shanghai Institute of Organic Chemistry expanded (Org. Lett. 2014, 16, 1810) the four-membered ring of 6 to create the cyclopentanone 7 in high ee. Damien Bonne and Jean Rodriguez of Aix-Marseille Université condensed (Chem. Eur. J. 2014, 20, 410) the cyclopentanone 8 with 9 to give 10. Santanu Mukherjee of the Indian Institute of Science, Bangalore added (Chem. Sci. 2014, 5, 1627) the lactone 12 to the prochiral 11 to give 13 with remarkable diastereo- and enantiocontrol. Yixin Lu of the National University of Singapore constructed (Angew. Chem. Int. Ed. 2014, 53, 5643) the cyclopentene 16 by adding 14 to the allene 15. Efraim Reyes and Jose L. Vicario of the Universidad del País Vasco prepared (Chem. Eur. J. 2014, 20, 2145) the highly substituted cyclohexene 19 by combining 17 and 18. Maurizio Benaglia of the Università degli Studi di Milano added (Adv. Synth Catal. 2014, 356, 493) the ketone 20 to 21 to create the cyclohexanone 22. Ben W. Greatrex of the University of New England in Australia used (J. Org. Chem. 2014, 79, 5088) an organocatalyst to cyclize the symmetrical dialdehyde 23 to the α-hydroxy ketone 24. Dieter Enders of RWTH Aachen added (Org. Lett. 2014, 16, 2954) the β-keto ester 25 to 26 to give an intermediate that was further condensed with 27 to complete the preparation of 28. Eric N. Jacobsen of Harvard University prepared (Angew. Chem. Int. Ed. 2014, 53, 5912) the cycloheptenone 30 by the enantioselective intermolecular addition of the pyrylium salt derived from 29 to ethyl vinyl ether. Bor-Cherng Hong of the National Chung Cheng University initiated (Org. Lett. 2014, 16, 2724) the assembly of the steroid derivative 33 by the enantioselective addition of 32 to the unsaturated aldehyde 31.
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Taber, Douglass F. "C–N Ring Construction: The Glorius Synthesis of ent-Monomorine." In Organic Synthesis. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190646165.003.0054.
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Ryan Gilmour of the Westfälische Wilhelms-Universität Münster employed (Chem. Eur. J. 2014, 20, 794) an organocatalyst to direct the enantioselective aziridination of 1 to 2. Vanessa Kar-Yan Lo and Chi-Ming Che of Hong Kong University devised (Angew. Chem. Int. Ed. 2014, 53, 2982) a Ru catalyst for the enantioselective aziridination (not illustrated) of terminal alkenes. Shu-Li You of the Shanghai Institute of Organic Chemistry and Aiwen Lei of Wuhan University described (Angew. Chem. Int. Ed. 2014, 53, 2443) the Pd-mediated carbonylation of 3 to the β-lactam 4. Professor You reported (J. Am. Chem. Soc. 2014, 136, 6590) the enantioselective allylation of a pyrrole 5 with 6 to give the imine 7. Maria-Paz Cabal and Carlos Valdés of the University of Oviedo showed (Eur. J. Org. Chem. 2014, 1672) that the cyclization of 8 to 9 proceeded with predictable high diastereocontrol. In one pot, Darren J. Dixon of the University of Oxford combined (ACS Catal. 2014, 4, 634) 10 and 11 to give 12 in high ee. The addition of 13 to 14 to give 15 described (Nature Chem. 2014, 6, 47) by Takashi Ooi of Nagoya University set two adjacent quaternary centers with control of both relative and absolute configuration. Scott E. Denmark of the University of Illinois devised (J. Am. Chem. Soc. 2014, 136, 8915) a catalyst for the enantioselective electrophilic cyclization of 16 to 17 with control of sidechain stereochemistry. Using commercial acetone cyanohydrin 19, Christian V. Stevens of Ghent University cyclized (Eur. J. Org. Chem. 2014, 1296) 18 to the nitrile 20. George W. J. Fleet, also of the University of Oxford, used (Eur. J. Org. Chem. 2014, 2053) similar conditions to convert the sugar-derived acetonide 21 into 22. Michael B. Tropak of the University of Toronto and Dilip P. Dhavale of the University of Pune showed (J. Org. Chem. 2014, 79, 4398) that the nitrone derived from 21 added to an alkene 23 with high facial selectivity, leading to the piperidine 24. In the course of a synthesis of syringolin A, Satoshi Ichikawa of Hokkaido University effected (Angew. Chem. Int. Ed. 2014, 53, 4836) intramolecular Ugi three-component coupling of the isonitrile 25, the acid 26, and the amine 27, leading to the macrolactam 28.
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Taber, Douglass F. "Organocatalyzed C–C Ring Construction: The Mihovilovic Synthesis of Piperenol B." In Organic Synthesis. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190646165.003.0072.
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M. Kevin Brown of Indiana University prepared (J. Am. Chem. Soc. 2015, 137, 3482) the cyclobutane 3 by the organocatalyzed addition of 2 to the alkene 1. Karl Anker Jørgensen of Aarhus University assembled (J. Am. Chem. Soc. 2015, 137, 1685) the complex cyclobutane 7 by the addition of 5 to the acceptor 4, followed by condensation with the phosphorane 6. Zhi Li of the National University of Singapore balanced (ACS Catal. 2015, 5, 51) three enzymes to effect enantioselective opening of the epoxide 8 followed by air oxidation to 9. Gang Zhao of the Shanghai Institute of Organic Chemistry and Zhong Li of the East China University of Science and Technology added (Org. Lett. 2015, 17, 688) 10 to 11 to give 12 in high ee. Akkattu T. Biju of the National Chemical Laboratory combined (Chem. Commun. 2015, 51, 9559) 13 with 14 to give the β-lactone 15. Paul Ha-Yeon Cheong of Oregon State University and Karl A. Scheidt of Northwestern University reported (Chem. Commun. 2015, 51, 2690) related results. Dieter Enders of RWTH Aachen University constructed (Chem. Eur. J. 2015, 21, 1004) the complex cyclopentane 20 by the controlled combination of 16, 17, and 18, followed by addition of the phosphorane 19. Derek R. Boyd and Paul J. Stevenson of Queen’s University Belfast showed (J. Org. Chem. 2015, 80, 3429) that the product from the microbial oxidation of 21 could be protected as the acetonide 22. Ignacio Carrera of the Universidad de la República described (Org. Lett. 2015, 17, 684) the related oxidation of benzyl azide (not illustrated). Manfred T. Reetz of the Max-Planck-Institut für Kohlenforschung and the Philipps-Universität Marburg found (Angew. Chem. Int. Ed. 2014, 53, 8659) that cytochrome P450 could oxidize the cyclohexane 23 to the cyclohexanol 24. F. Dean Toste of the University of California, Berkeley aminated (J. Am. Chem. Soc. 2015, 137, 3205) the ketone 25 with 26 to give 27. Benjamin List, also of the Max-Planck-Institut für Kohlenforschung, reported (Synlett 2015, 26, 1413) a parallel investigation. Philip Kraft of Givaudan Schweiz AG and Professor List added (Angew. Chem. Int. Ed. 2015, 54, 1960) 28 to 29 to give 30 in high ee.
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Taber, Douglass F. "Organocatalyzed C–C Ring Construction: The Hayashi Synthesis of PGE1 Me Ester." In Organic Synthesis. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190200794.003.0073.
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Xiaohua Liu and Xiaoming Feng of Sichuan University devised (J. Org. Chem. 2013, 78, 6322) a catalyst that mediated the addition of the ylide 2 to the enone 1 to give 3. Peng-fei Xu of Lanzhou University found (Chem. Commun. 2013, 49, 4625) that the vinyl pyrrole 4 was sufficiently nucleophilic to add to 5, leading to the cyclobutane 6. Albert Moyano of the Universitat de Barcelona added (Eur. J. Org. Chem. 2013, 3103) 8 to the unsaturated aldehyde 7 to give the β-amino acid precursor 9. Eugenia Marqués-López and Mathias Christmann, now at Freie Universität Berlin effected (Synthesis 2013, 45, 1016) the intramolecular Michael cyclization of 10 to give 11. Delong Liu and Wanbin Zhang of Shanghai Jiao Tong University showed (Synthesis 2013, 45, 1612) that 12 and 13 could be combined to give the cyclopentane 14. Ismail Ibrahem and Armando Córdova of Mid Sweden University combined (Angew. Chem. Int. Ed. 2013, 52, 6050) 15 and 16 to give 17, with good control of the quaternary center. Kamal Nain Singh of Panjab University prepared (Synthesis 2013, 45, 1406) a proline-derived sulfoxide that mediated the addition of cyclohexanone 18 to 19. Intramolecular aldehyde alkylation is underdeveloped as a synthetic method. David W.C. MacMillan of Princeton University established (J. Am. Chem. Soc. 2013, 135, 9358) a single-electron transfer variant, cyclizing 21 to 22. Arianna Quintavalla of the University of Bologna effected (Adv. Synth. Catal. 2013, 355, 938) the double addition of nitromethane 24 to 23 to give 25. John Cong-Gui Zhao of the University of Texas at San Antonio reported (Chem. Eur. J. 2013, 19, 1666; J. Org. Chem. 2013, 78, 4153) parallel results (not pictured) with aryl enones as the acceptors. Bor-Cherng Hong of the National Chung Cheng University condensed (Eur. J. Org. Chem. 2013, 2472) 26 with the alcohol 27 to give 28. Again, good control of the quaternary center was observed. Marc C. Kimber of Loughborough University used (J. Org. Chem. 2013, 78, 3476) an organocatalyst to rearrange the prochiral endoperoxide 29 to the hydroxy enone, to which malonate 30 was added to give 31.
Conference papers on the topic "Ring catalog"
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Sawicki, Jerzy T., Samuel A. Johansson, John H. Rumbarger, and Ronald B. Sharpless. "Fatigue Life Prediction for Large-Diameter Elastically-Constrained Ball Bearings." In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27564.
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The application of large-diameter bearing rings and the thereof inherited low stiffness make them susceptible to local distortions caused by their surrounding structures, which are often under heavy loads. The standard accepted design criteria for these bearings are based on the estimation of the internal load distribution of the bearing, under the assumption of rigid circular and flat supporting structures, that keep the bearing inner and outer races in circular, flat, i.e., not deformed shapes. However, in the presence of structural distortions, the element load distribution can be severely altered and cannot be predicted via the standard design criteria. Therefore, the application of large-diameter ball and roller bearing rings as the critical components in rotating machines becomes more of a design task than making a catalog selection. The analytical and finite element approach for fatigue life prediction of such a bearing-application is presented. The undertaken approach and the results are illustrated based on the analysis and fatigue life simulation of the CT (Computed Tomography) -scanner’s main rotor bearing. It has been demonstrated that flexibility of the rings can significantly reduce the fatigue life of the ball bearing.
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Chatterton, S., P. Pennacchi, A. Vania, E. Tanzi, and R. Ricci. "Characterization of Five-Pad Tilting-Pad Journal Bearings Using an Original Test-Rig." In ASME 2011 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/detc2011-48166.
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Tilting-pad journal bearings are installed with increased frequency owing to their dynamic stability characteristics in several rotating machine applications, typically in high rotating speed cases. This usually happens for new installations in highspeed compressors or during revamping operations of steam and gas turbines for power generation. The selection from a catalogue, or the design of a new bearing, requires the knowledge of the bearing characteristics such as babbitt metal temperatures, fluid-film thickness, load capacity, stiffness and damping coefficients. Temperature and fluid-film thickness are essential for the safety of the bearing. Babbitt metal is subject to creep at high temperatures, as it happens at high speed operations. On the contrary, at low speed or with high loads, oil-film thickness could be too low, resulting in metal to metal contact. Oil-film dynamic coefficients are largely responsible of the dynamic behaviour and of the stability of the rotor-tilting-pad-bearing system. Therefore, the theoretical evaluation and/or the experimental estimation of these coefficients are mandatory in the design phase. The theoretical evaluation of these coefficients for tilting pad journal bearings is difficult due to their complex geometry, boundary and thermal conditions and turbulent flow, whereas an experimental characterization requires a suitable test rig. The paper describes the test rig designed to this purpose and its unusual configuration with respect to other test rigs available in literature. Some preliminary tests performed for the bearing characterization are also shown.
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Pease, Leonard F., Judith Ann Bamberger, and Michael J. Minette. "Erosion Front Patterns in Pulse Jet Mixed Vessels." In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-71133.
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Here we observe the spatial and temporal patterns that erosion fronts driven by pulsed radial wall jets develop in double ring arrays of pulse tubes within slurry mixing vessels with curved bottoms. Although erosion of unbounded particle beds driven by individual steady jets has been studied for decades, the patterns developed within mixing vessels as neighboring transient erosion fronts collide and the subsequent relaxation of the particle bed towards the vessel center when the jets stop (i.e., as the pulse tubes refill within mixing vessels) remain incompletely understood. Relaxation here refers to motion of fluidized particle beds that were driven toward the vessel seam by radial wall jets that subsequently return or relax from the seam toward the center of the vessel when the jets turn off. Relaxation does not refer to downward individual or hindered particle settling. Spatial variations in the particle bed due to these relaxing particle beds comprise an important “initial” condition to the mathematical description of the evolution of the jet driven erosion front, and erosion fronts other than the one that expands radially from the pulse tube axis have only recently been described. For example, Bamberger, et al. (2017) [9], recently evaluated five selected cases of erosion patterns found in vessels 15 and 70 inches in diameter with 2:1 semi-elliptical bottoms. A highlight of that study was the discovery of a second type of erosion front that forms at the plane of symmetry between two adjacent pulse tubes. As neighboring radial wall jets collide they form an upwelling sheet of fluid; this second type of erosion front forms immediately beneath this upwelling flow. However, variations in this type of planar erosion front have not been cataloged previously. In this study, we systematically probe the erosion fronts driven by these upwelling sheets in greater detail and evaluate the relaxation of the particle bed to its “initial” condition after the pulse ceases. Variations in the erosion patterns and particle bed relaxation are evaluated as a function of particle concentration, density, and size. This study specifically focusses on video images collected from the 15 inch vessel because it provides distinctive visualization of erosion pattern behavior. We find the upwelling sheets to be more influential on the erosion patterns at lower particle concentrations, making these findings particularly important to low solids concentration vessels. At lower particle concentrations, flow at the base of the plane of symmetry readily erodes particle beds. At higher particle concentrations, piles of unmobilized solids accumulate beneath colliding jets either because the erosion mechanism vanishes or because erosion at the plane of symmetry is slow compared to radial erosion. We also find that the upwelling sheets introduce a flow that drives erosion patterns from outer ring jets toward the vessel center along the curved vessel floor along the plane of symmetry between nozzles. We further find that the rate of particle bed relaxation back toward the vessel center after the pulse ceases may correlate with concentration, particle density, and size. Higher concentrations and particle densities relax faster. The rate at which the entire bed relaxes toward the vessel center is faster near the vessel seam but slows as the relaxing front approaches the vessel center. This paper discusses competing mechanisms to explain these observations, including particle rolling, bed avalanches, gravity driven fluidized bed motion, and suspended particle sedimentation.
Reports on the topic "Ring catalog"
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Tilak, Anup S., Herbert A. Leupold, II Potenziani, and Ernest. Magnetic Rings: Catalogue of Field Profiles. Defense Technical Information Center, 1992. http://dx.doi.org/10.21236/ada261466.
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