1,471 research outputs found
Evaluation of Water Exchange Kinetics on [Ln(AAZTAPh–NO2)(H2O)q]x Complexes Using Proton Nuclear Magnetic Resonance
No full textWater exchange kinetics on [Ln(AAZTAPh–NO2)(H2O)q]− (Ln = Gd3+, Dy3+, or Tm3+) were determined by 1H nuclear magnetic resonance (NMR) measurements. The number of inner-sphere water molecules was found to change from two to one when going from Dy3+ to Tm3+. The calculated water exchange rate constants obtained by variable-temperature proton transverse relaxation rates are 3.9 × 106, 0.46 × 106, and 0.014 × 106 s–1 at 298 K for Gd3+, Dy3+, and Tm3+, respectively. Variable-pressure measurements were used to assess the water exchange mechanism. The results indicate an associative and dissociative interchange mechanism for Gd3+ and Dy3+ complexes with ΔV⧧ values of −1.4 and 1.9 cm3 mol–1, respectively. An associative activation mode (Ia or A mechanism) was obtained for the Tm3+ complex (ΔV⧧ = −5.6 cm3 mol–1). Moreover, [Dy(AAZTAPh–NO2)(H2O)2]− with a very high transverse relaxivity value was found as a potential candidate for negative contrast agents for high-field imaging applications.LCI
Structural and dynamic parameters obtained from (17)O NMR, EPR, and NMRD studies of monomeric and dimeric Gd(3)+ complexes of interest in magnetic resonance imaging: an integrated and theoretically self-consistent approach(1)
No full textD. Hugh Powell, Orla M. Ni Dhubhghaill, Dirk Pubanz, Lothar Helm, Yakob S. Lebedev, Willi Schlaepfer, and André E. Merbac
Relevance of the ligand exchange rate and mechanism of fac-[(CO)3M(H2O)3]+ (M = Mn, Tc, Re) complexes for new radiopharmaceuticals
No full textCopyright © 2006 American Chemical SocietyPascal V. Grundler, Lothar Helm, Roger Alberto, and André E. Merbac
Water-Exchange Study Revealed Unexpected Substitution Behavior of [(CO)2(NO)Re(H2O)3]2+ in Aqueous Media
No full textCopyright © 2006 American Chemical SocietyMarie-Line Lehaire, Pascal V. Grundler, Stefan Steinhauser, Niklaus Marti, Lothar Helm, Kaspar Hegetschweiler, Roger Schibli, and André E. Merbac
Kinetic studies on the first dihydrogen aquacomplex, [Ru(H(2))(H(2)O)(5)](2+): Formation under H(2) pressure and catalytic H/D isotope exchange in water
No full textCopyright © 2005 Elsevier B.V. All rights reserved.Pascal V. Grundler, Oleg V. Yazyev, Nicolas Aebischer, Lothar Helm, Gábor Laurenczy and André E. Merbac
Languages and international virtual exchange
No full textIntroduction to a special edition of the journal. The article briefly reviews new developments in virtual exchange on a policy level, and then provides a short summary of each of the articles in this special edition. The author of this introduction was co-editor of this special edition of the journal
Cwbr Author Interview: This Vast Southern Empire: Slaveholders At The Helm Of American Foreign Policy
No full textInterview with Matthew Karp, author of This Vast Southern Empire: Slaveholders at the Helm of American Foreign Policy Interviewed by Tom Barber Civil War Book Review (CWBR): Today the Civil War Book Review is happy to speak with Matthew Karp, Assistant Professor of History at Princeton Uni...
A Dialogic Model for Telecollaboration
No full textIn language learning contexts, telecollaboration is understood to be internet-based intercultural exchange between people of different cultural/national backgrounds set up in an institutional context with the aim of developing both language skills and intercultural communicative competence. Generally students interact with one another on 'safe' topics and subsequently reflect on and discuss their interactions with teachers and peers. This paper presents a dialogic model of telecollaboration which breaks from this tradition as it entails interaction on topics which are seen as divisive through dialogue in groups led by trained facilitators, the Soliya Connect Program (SCP). The differences between this model of telecollaboration and traditional models are illustrated, and then the author presents the results of a survey study which looks at participants' evaluation of this program, what they perceive to be the role of the facilitators and their personal learning outcomes.Nell'apprendimento linguistico, 'telecollaboration' significa scambio interculturale online tra persone di diverse culture, organizzato a livello istituzionale, con l'obiettivo di sviluppare sia competenze linguistiche che interculturali attraverso attività strutturate. Solitamente, partecipanti discutono su argomenti 'sicuri' e poi riflettono sulle interazioni in classe con il docente. Questo articolo presenta un nuovo modello di telecollaboration, Soliya Connect Program, che si differenzia da questa tradizione in quanto partecipanti discutono argomenti contenziosi sotto la guida di facilitatori esperti. Vengono illustrate le differenze tra questi diversi modelli di telecollaboration e in seguito sono presentati i risultati di uno studio che indaga la valutazione di questo progetto da parte dei partecipanti, il ruolo dei facilitatori e i risultati di apprendimento percepiti dai partecipanti.En contextos de aprendizaje de idiomas, telecolaboración se entiende como el intercambio intercultural, facilitado vía Internet, entre las personas de diferentes orígenes culturales / nacionales. La interacción es construida en un contexto institucional con el objetivo de desarrollar tanto las habilidades lingüísticas como las competencias comunicativas e interculturales. En general, los estudiantes interactúan entre sí sobre temas "seguros" y, posteriormente, reflexionan y discuten sobre sus interacciones con los profesores y compañeros. En este trabajo se presenta un modelo dialógico de telecolaboración que rompe con esta tradición, ya que implica la interacción sobre temas que se consideran de división o conflictivos, a través del diálogo en grupos dirigidos por mediadores capacitados (dentro del Programa Connect Soliya). Se ilustran las diferencias entre este modelo de telecolaboración y los modelos tradicionales. La autora presenta los resultados de un estudio de investigación que analiza la evaluación de los participantes de este programa, como perciben el papel de los mediadores y los resultados personales de aprendizaje
Technology and Language Learning. What the Learners Say
No full textThis paper, based on a plenary talk given at UNAM in Mexico in 2006 gives a brief overview of some recent research reports and surveys on technology and learning, particularly learner attitudes to ICT, including a survey carried out by the author at the University of Padova. It looks at some of the possible implications of research results for the use of technology in language learning, with particular reference to the self access context. Finally, the paper explores some ways in which self access centres can use technology to take into account current social-constructivist approaches to language learning, to foster learner autonomy and meet the needs of students who have to become effective language users in the information and communication society we now live in
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