6,690 research outputs found
Phenyl vs. ferrocenyl cyclometallation selectivity: diastereoselective synthesis of an enantiopure iridacycle
No full textFerrocenyl (Fc) and phenyl (Ph) containing imines FcCH=NCH(R)Ph and FcCH(R)N=CHPh (R = H and Me) were cycloiridated using [Cp*IrCl2]2 with NaOAc in CH2Cl2. All resulted in the formation of neutral chloride ligated half-sandwich iridacycles as a result of ortho-phenyl and not alpha-ferrocenyl C–H activation. The complexes derived from FcCH=NCH(R)Ph (R = H,Me) were obtained as a mixture of E and Z imine isomers, and with R = Me the product obtained from the (S)-imine was isolated by recrystallisation as a single diastereoisomer. The configuration was determined by an X-ray crystal structure analysis as SC,RIr,E
Subsurface mapping of the Ross Island flexural basin, southwest Antarctica
No full text2016 Summer.Includes bibliographical references.Ross Island is a post-Miocene (< 4.6 Ma) volcanic island located in the Ross Sea region of southwest Antarctica. This region of Antarctica borders the western edge of the West Antarctic Rift System, along the Transantarctic Mountain front. Marine and over-ice multi-channel seismic reflection surveys and borehole studies targeting the Ross Sea region over the last 30+ years have been used in this study to develop a seismic stratigraphic model of the development and evolution of the Ross Island flexural basin. Four key stratigraphic horizons were identified and mapped to fully capture the basin-fill, as well as strata lying above and below the flexural basin. From oldest to youngest these horizons are named RIB-m, RIM-g, RIM-b and RIB-r. Time structure, isochron and isochore maps were created for the horizons and the stratigraphic intervals they bound. The seismic stratigraphic record shows the Ross Island flexural moat formation post-dates the main tectonic subsidence phase within the Victoria Land Basin. The maps presented here are the first to fully illustrate the evolution of the Ross Island flexural basin. The maps highlight depositional patterns of two distinct periods of flexural subsidence and basin-filling superimposed on the older N-S trending Victoria Land Basin depocenter. Two units of flexural basin fill, Unit FFI between horizons RIM-g and RIM-b (the oldest flexural basin fill), and Unit FFII between horizons RIM-b and RIB-r (the youngest flexural basin fill) are associated with the two periods of flexural subsidence. Flexural moat subsidence and subsequent filling occurred episodically during periods of active volcanism on the island. Unit FFI is estimated to range from ca. 4 to 2 Ma, corresponding with formation of the Mt. Bird volcanic edifice on Ross Island. Unit FFII ranges in age from ca. 2 to 1 Ma, and is related to Mt. Terror, Mt. Erebus, and Hut Point Peninsula volcanism. The isochore maps suggest the depocenter of the flexural basin during both time intervals was located north of the island, instead of directly beneath the Ross Island topographic load. Factors contributing to the northerly location of the depocenter include i) volcanic loading by McMurdo Volcanic Group subsea volcanic features north of the island, ii) partial compensation of the main Ross Island load by low-density, partially molten rock beneath the island, iii) extensional faulting within the Terror Rift, and iv) seaward-thickening shelf sediments transported from the Ross Ice Shelf. The seismic data show that the onset of filling of the flexural moat around Ross Island coincided with the end of ice grounding events in the area. We infer that this was caused by flexural subsidence of the seafloor to accommodate the Ross Island load
R code for: A fat chance of survival: Body condition provides life-history dependent buffering of environmental change in a wild mammal population
No full textAll R code files used in the analysis of data for "A fat chance of survival: Body condition provides life-history dependent buffering of environmental change in a wild mammal population", published in Climate Change Ecology (doi: 10.1016/j.ecochg.2021.100022). For any questions, as well as the data underpinning these analyses, please reach out to the corresponding author: [email protected]
Dacron Graft Encased Modified Ross Operation
No full textThe pulmonary autograft operation was introduced by Donald Ross in 1967. Since then, the Ross operation has become a viable and durable option for aortic valve replacement in both the pediatric and adult populations (1). Pulmonary autograft dilatation is one of the complications noted in the adult population. Because of this, the Ross operation is showing a declining trend in this adult population. To prevent this complication, Ross Ungerleider came up with a simple and reproducible modification by adding a Dacron tube graft over the pulmonary autograft, and found no pulmonary autograft dilatation in 30 patients over the period of four years (2).The concerns raised with the modified Ross procedure are that the Dacron tube graft is a cylindrical graft and the sinus portion of the autograft is essential for the normal functioning of the leaflets, as studied in valve-sparing aortic root replacement procedures and experimental studies, and the modified Ross procedure does not address and prevent the potential threat to the valve leaflets function in the long term (3). The pseudosinus creation in the Dacron graft is very important to decrease the stress and strain on the leaflets, so that it is closer to normal, as studied by K .Jane Grande-Allen et al (3).Keeping this in mind, the author has made an additional modification to the modified Ross operation by removing the autograft sinuses, which were getting restricted by the cylindrical Dacron graft, and creating a pseudosinus/neosinus in the Dacron graft.With these modifications to the modified Ross operation, the author hopes to take care of the pulmonary autograft dilatation at all three levels:Annular level – The author sutures the autograft to the Dacron graft and then to the aortic annulus, which prevents annular dilatation.Sinuses – By excising the native autograft sinuses, which are being restricted by the Dacron graft, and creating the pseudosinus/neosinus in the Dacron graft, the author hopes to preserve the valve leaflet function.Sinotubular junction – Since the author is fixing the commissures to the Dacron graft and then suturing the Dacron graft to the ascending aorta, the dilatation at the sinotubular junction is nullified.ReferencesRoss DN. Replacement of aortic and mitral valves with a pulmonary autograft. Lancet. 1967;290(7523):956-958.Ungerleider RM, Ootaki Y, Shen I, Welke KF. Modified Ross procedure to prevent autograft dilation. Ann Thorac Surg. 2010;90(3):1035-1037. </p
Foreword: Special issue on particle methods for the oil and gas industry
No full textIt is with great pleasure that I introduce this Special Issue of Computational Particle Mechanics, titled Particle Methods for the Oil and Gas Industry. It brings together 11 original research articles from academics around the world, all focused on an industry of international significance
Service sector reform options: the experience of China
No full textChristopher Findlay, Mari Pangestu and Roy Chun Leehttp://epress.anu.edu.au/chinalink_citation.htm
sj-pdf-2-wem-10.1177_10806032241248422 - Supplemental material for Wilderness Medical Society Clinical Practice Guidelines for the Treatment of Acute Pain in Austere Environments: 2024 Update
No full textSupplemental material, sj-pdf-2-wem-10.1177_10806032241248422 for Wilderness Medical Society Clinical Practice Guidelines for the Treatment of Acute Pain in Austere Environments: 2024 Update by Patrick B. Fink, Albert R. Wheeler, William R. Smith, Graham Brant-Zawadzki, James R. Lieberman, Scott E. McIntosh, Christopher Van Tilburg, Ian S. Wedmore, Jeremy S. Windsor, Ross Hofmeyr and David Weber in Wilderness & Environmental Medicine</p
Research cruise of the R/V Italica in the Ross Sea: The 14th Italian Antarctic Research Expedition (ANTA98/99)
No full textInternational co-operative Antarctic research between Japan and Italy started in 1998. The senior author, Masao Iwai, participated as a marine geologist on the R/V Italica's cruise ANTA98/99, the 14th Italian Antarctic Research Expedition, in the Ross Sea from January 5 through February 23, 1999. The scientific and administrative operation of onboard coring and laboratory equipment of R/V Italica, and the life style, are introduced
The elite household in England, 1100-1550: proceedings of the 2016 Harlaxton Symposium
No full textHere are 22 peer-reviewed essays by leading scholars exploring the social, economic and artistic aspects of the great households of medieval England, The essays are grouped in eight sections exploring how the households of the elite were centres for politics, literature (both a location of production and a subject of literary works), education, music and, of course, conspicuous consumption, with the need for many servants and sources of supply. The extraordinary range of subjects covered are revealed by a subject index, supplemented by a comprehensive index of people and places. The essays are by Christopher Woolgar, Christopher Dyer, Louise J. Wilkinson, David Stocker, James Ross, Michael Johnston, D. Vance Smith, Elliot Kendall, Nicholas Orme, Claire Weeda, Fiona Whelan, Roger Bowers, Richard Rastall, Martin Heale, Jennifer Ward, Susan Powell, Caroline Dunn, Martha Carlin, David Green, Eleanor R. Standley, Anne Rudloff Stanton and Maria Hayward
Stereoselective and stereospecific reactions of cobalt sandwich complexes: Synthesis of a new class of single enantiomer bulky planar chiral P−N and P−P ligands
No full textStarting from (η5-acetylcyclopentadienyl)(η4-tetraphenylcyclobutadiene)cobalt(I), highly enantioselective (99 % ee) (S)-CBS catalysed ketone reduction followed by stereospecific alcohol-azide exchange, azide reduction and dimethyllation gave (R)-(η5-α-N,N-dimethylaminoethylcyclopentadienyl)(η4-tetraphenylcyclobutadiene) cobalt(I) (Arthurs’ amine). This underwent highly diastereoselective cyclopalladation to give di-μ-acetate-bis-(R)-[(η5-(Sp)-2-(α-N,N-dimethylaminoethyl)cyclopentadienyl, 1-C, N)(η4-tetraphenylcyclobutadiene)cobalt(I)]dipalladium, and highly diastereoselective lithiation to give (R)-(η5-(Sp)-1-(α-N,N-dimethylaminoethyl)-2-(diphenylphosphino)cyclopentadienyl)(η4-tetraphenylcyclobutadiene)cobalt(I) (PPCA) following the addition as electrophile of chlorodiphenylphosphine. This PN-ligand was converted into (R)-(η5-(Sp)-1-(α-dicyclohexylphosphinoethyl)-2-(diphenylphosphino)cyclopentadienyl)(η4-tetraphenylcyclobutadiene)cobalt(I), a PP-ligand (Rossiphos), by stereospecific amine-phosphine exchange using HPCy2. These air-stable P−N and P−P complexes are the first examples of a new class of bulky planar chiral ligands for application in asymmetric catalysis
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