1,092 research outputs found
SOLVENT EFFECTS ON TRIPLET LIFETIMES---BENZENE AT LOW TEMPERATURES
No full textPresent address of G. C. Nieman: Department of Chemistry, Muskingum College, New Concord, Ohio 13762.""Author Institution: Department of Chemistry, University of RochesterThe lifetime of the lowest benzene triplet state has been shown recently to be strongly dependent, upon temperature, even near . We report here on the solvent dependence of the phosphorescence lifetime of benzene and methylbenzenes in the low temperature limit. At the lifetime of varies from 12.5 to 26.5 seconds depending upon the solvent. The shortest lifetimes are found with solvents which have excited states closest in energy to those of benzene. There is some indication of the formation of a weak exciplex and subsequent radiationless decay. The longest lifetimes are found with perfluorocarbon solvents (e.g., )
Integrating CT Myocardial Perfusion and CT-FFR in the Work-Up of Coronary Artery Disease
No full textAdriaan Coenen, Marisa Lubbers and Koen Nieman were supported by a grant from the Dutch
Heart Foundation (NHS 2014T061).
Francesca Pugliese: This work forms part of the translational research portfolio of the NIHR
Cardiovascular Biomedical Research Unit at Barts, which is supported and funded by the NIHR.
Alexia Rossi: recipient of a Training Grant by the European Society of Cardiology (2014)
Three-dimensional volume rendering with multislice computed tomography in the evaluation of Aortic coarctation
No full textCoronary artery anomalies are some of the most confusing, neglected topics in cardiology. Presently, no techniques are able to routinely screen those morphological alterations which can create potentially life-threatening complications, especially in young healthy subjects. Many efforts have been made to non-invasively image the coronary arteries using magnetic resonance, electron beam computed tomography, and recently multidetector computed tomography (MDCT). Even though interesting results have been reported, these techniques have hardly become an adequate substitute for conventional catheter coronary angiography. A new generation of MDCT scanners with 16 arrays of detectors and a higher temporal and spatial resolution have recently been introduced. We report a case of an anomalous coronary artery origin documented using a 16-slice MDCT scanner
LUP888691 Supplemetal Material - Supplemental material for Prevalence and incidence of systemic lupus erythematosus and associated outcomes in the 2009–2016 US Medicare population
No full textSupplemental material, LUP888691 Supplemetal Material for Prevalence and incidence of systemic lupus erythematosus and associated outcomes in the 2009–2016 US Medicare population by S Li, T Gong, Y Peng, K M Nieman and D T Gilbertson in Lupus</p
Sviluppi tecnici futuri: evoluzione o rivoluzione?
No full text(Cap. 40 - Parte IV Indicazioni, integrazione tra metodiche e sviluppi
Modificatie van nylon 6 en 6.6 met een vetzuur polyamide
No full textEr is onderzoek gedaan naar de mogelijkheid om het vetzure polyamide nylon 6.36, op basis van het C-36 dimere vetzuur (Pripol 1009) en hexamethyleendiamine, te gebruiken voor de modificatie van nylon 6.6. Hiervoor moet er een copolymeer op basis van adipinezuur, dimeer en hexamethyleendiamine gemaakt worden. Fysisch mengen en omamideren van de homopolymeren leidde niet tot een blend met voldoende compatibiliteit. Om copolymerisatie via grensvlakpolycondensatie uit te voeren moet men beschikken over de dizuurchlorides van het dimeer en adipinezuur. Deze kunnen met grote zuiverheid gesynthetiseerd worden met oxalylchloride. De grensvlakpolycondensatie leidde bij de gekozen condities niet tot een random copolymeer. Polymerisatie in een slecht regelbare autoclaaf uitgaande van nylonzout en dimeerzout resulteerde in niet reproduceerbare produkten. Door de slechte oplosbaarheid van dimeerzout in water of het hoge smeltpunt van nylonzout was de reactie in alle gevallen heterogeen. De polymerisatie werd hier niet door kinetiek of thermodynamica bepaald, maar door fysische grootheden als druppel of kristalgrootte, mate van menging, e.d. . De polymerisatie van caprolactam met dimeerzout is daarentegen homogeen, omdat er een volledig homogene oplossing van beide componenten ontstaat. De reactie wordt hier niet door toevalligheden bepaald. De geproduceerde materialen op basis van nylonout en dimeerzout zijn vergeleken met van een fabrikant verkregen copolymeren op basis van caprolactam, hexamethyleendiamine en dimeer. De analysemethoden die hiervoor gebruikt zijn, waren: differential scanning calorimetrie, gelpermeatiechromatografie en torsiemetingen ter bepaling van de dynamische moduli. Met de verkregen nylon 6/6.36 copolymeren zijn bovendien trekproeven uitgevoerd.Applied SciencesScheikundige Technologie en MateriaalkundeTechnologie van Macromoleculaire Stoffe
Non-invasive 16-row spiral multislice computed tomography coronary angiography after one year of experience
No full textThe gold standard for direct diagnostic imaging of coronary arteries is still conventional X-ray coronary angiography, even though for several other applications, noninvasive techniques substituted invasive ones. In the last 10 years several techniques (magnetic resonance, electron beam tomography, spiral computed tomography) attempted to emerge as noninvasive modality for the study of coronary arteries. The introduction of multislice computed tomography (MSCT) with retrospectively gated ECG reconstructions has substantially modified the coronary imaging scenario. In fact, the results have been promising since the beginning with 4-row MSCT. Currently the results reported with 16-row MSCT allow to question which role can the noninvasive coronary angiography play in clinical settings. With a scan of < 20 s after intravenous administration of iodinated contrast material it is possible to obtain information similar to conventional coronary angiography. Moreover, together with vascular patency, also atherosclerotic plaques are well visualized and characterized (type: calcified, soft, mixed). Ongoing studies are validating MSCT in the assessment of plaque vulnerability. The same technique allows to evaluate left ventricular function and myocardial wall motion impairment. Still with a few major limitations related to the heart rate, MSCT will broaden the noninvasive capability of evaluating coronary arteries in patients where conventional coronary angiography is exceeding the actual clinical question or considered as premature
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