[reaction: see text] A divergent synthesis of internally functionalized dendrimers based on a modular functional monomer has been developed. This strategy was applied to the construction of a light-harvesting dendrimer containing one set of naphthopyranone dyes located at the interior and another set of coumarin chromophores located in the adjacent outer layer surrounding a porphyrin acceptor. Quantitative energy transfer from both donor pigments is observed, giving rise to exclusive emission from the porphyrin core over all excitation wavelengths.
The Coast Range ophiolite of California is one of the most extensive ophiolite terranes in North America, extending over 700 km from the northernmost Sacramento Valley to the southern Transverse Ranges in central California. This ophiolite, and other ophiolite remnants with similar mid-Jurassic ages, represent a major but short-lived episode of oceanic crust formation that affected much of western North America. The history of this ophiolite is important for models of the tectonic evolution of western North America during the Mesozoic, and a range of conflicting interpretations have arisen. Current petrologic, geochemical, stratigraphic, and radiometric age data all favor the interpretation that the Coast Range ophiolite formed to a large extent by rapid extension in the fore-arc region of a nascent subduction zone. Closer inspection of these data, however, along with detailed studies of field relationships at several locales, show that formation of the ophiolite was more complex, and requires several stages of formation. Our work shows that exposures of the Coast Range ophiolite preserve evidence for four stages of magmatic development. The first three stages represent formation of the ophiolite above a nascent subduction zone. Rocks associated with the first stage include ophiolite layered gabbros, a sheeted complex, and volcanic rocks with arc tholeiitic or (more rarely) low-K calc-alkaline affinities. The second stage is characterized by intrusive wehrlite-clinopyroxenite complexes, intrusive gabbros, Cr-rich diorites, and volcanic rocks with high-Ca boninitic or tholeiitic ankaramite affinities. The third stage includes diorite and quartz diorite plutons, felsic dike and sill complexes, and calc-alkaline volcanic rocks. The first three stages of ophiolite formation were terminated by the intrusion of mid-ocean ridge basalt dikes, and the eruption of mid-ocean ridge basalt or ocean-island basalt volcanic suites. We interpret this final magmatic event (MORB dikes) to represent the collision of an active spreading ridge. Subsequent reorganization of relative plate motions led to sinistral transpression, along with renewed subduction and accretion of the Franciscan Complex. The latter event resulted in uplift and exhumation of the ophiolite by the process of accretionary uplift.
Fast Na-ion diffusion in Na<sub>3</sub>PS<sub>x</sub>Se<sub>4−x</sub> may not be causally related with the symmetry of the polymorph, but with compositional variations.
An organized delivery system is a network of organizations that provides or arranges to provide a coordinated continuum of services to a defined population and is willing to be held clinically and fiscally accountable for the outcomes and the health status of the population served. As such, organized delivery systems are at the center of efforts to implement health care reform. Based on analysis of 12 such systems, this article identifies key characteristics that influence what organized delivery systems are able to do, outlines the major obstacles or challenges to achieving greater levels of integration, and then discusses a number of approaches for effectively dealing with these obstacles.
article Free Access Share on A study of priority pricing in multiple service class networks Authors: Ron Cocchi Computer Science Department, University of Southern California, Los Angeles, California Computer Science Department, University of Southern California, Los Angeles, CaliforniaView Profile , Deborah Estrin Computer Science Department, University of Southern California, Los Angeles, California Computer Science Department, University of Southern California, Los Angeles, CaliforniaView Profile , Scott Shenker Palo Alto Research Center, Xerox Corporation, Palo Alto, Ca Palo Alto Research Center, Xerox Corporation, Palo Alto, CaView Profile , Lixia Zhang Palo Alto Research Center, Xerox Corporation, Palo Alto, Ca Palo Alto Research Center, Xerox Corporation, Palo Alto, CaView Profile Authors Info & Claims ACM SIGCOMM Computer Communication ReviewVolume 21Issue 4Sept. 1991 pp 123–130https://doi.org/10.1145/115994.116005Published:01 August 1991Publication History 49citation680DownloadsMetricsTotal Citations49Total Downloads680Last 12 Months27Last 6 weeks4 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my Alerts New Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF
The amination of aryl halides in the presence of inexpensive and air-stable alkali metal hydroxide bases and Pd[P(t-Bu)3]2 as catalyst gave arylamines in high yields. The reactions were conducted with a catalytic amount of cetyltrimethylammonium bromide as phase-transfer agent and either aqueous hydroxide or solid hydroxide in the presence of water. This combination of alkali metal hydroxide base, H2O, and the ammonium salt performed as well as NaO-t-Bu in the amination of p-chlorotoluene with dibutylamine. Hydroxide base was suitable for reactions of a wide range of aryl chlorides and bromides with aliphatic and aromatic amines. Some functional groups that were intolerant of tert-butoxide base, such as esters, enolizable ketones, nitriles, and nitro groups, were tolerated by the combination of hydroxide base, H2O, and cetyltrimethylammonium bromide in toluene solvent.
