122,834 research outputs found
Developments of time-resolved XAFS spectroscopy techniques – applications in homogeneous catalysis
No full textCatalysis is one of the most important methods to obtain products in a selective and sustainable manner, i.e. in an environmental responsible manner. To be able to modify and optimize these catalytic production pathways, it is important to obtain knowledge on the reaction mechanisms occurring. X-ray Absorption Fine Structure spectroscopy is a very powerful technique to obtain detailed electronic and structural information about the homogeneous catalysts in their chemical active environment, in situ and time-resolved, and derive structure – performance relationships and reaction mechanisms. In this thesis the application of XAFS spectroscopy in homogeneous catalytic systems is explored. Theory and data-analysis procedures to reliable analyze and interpret the obtained XAFS data, and instrumentation to monitor homogeneous catalytic reactions in situ and in a time-resolved mode were developed. A number of important homogeneous reactions are studied in detail. In the standard scanning data acquisition mode, EXAFS spectra are obtained in timescales that vary from minutes to hours. An alternative data acquisition method, i.e. the energy dispersive (ED) mode, has been developed which allows short collection times and thus enables structural information on dynamic systems. The ED-XAFS technique is further developed to apply to homogeneous catalytic systems. Moreover, a new set-up was developed to allow simultaneous time-resolved UV-Vis and ED-XAFS measurements (Chapter 2). The limited amount of applications of XAFS spectroscopy in homogeneous catalysis so far is most likely due to the complicated data-analysis of EXAFS data of organometallic compounds. In Chapter 3 a new refined data-analysis procedure is developed which accurately analyzes these EXAFS data. Application of the difference file technique while fitting in R-space, allows one to examine the different individual contributions to the total EXAFS spectrum in detail. In combination with the use of different k-weightings, antiphase behavior of different contributions can be detected and accounted for. The procedure is solely based on EXAFS parameters making it applicable to every EXAFS spectrum. Although crystal structures of many homogeneous catalysts are known, the structures in reaction medium are often not clear. Characterizing the organometallic compounds in reaction medium (solution) reveals essential structural information, which directly establishes structure-selectivity relationships in important Cu and Pd catalyzed reactions as shown in Chapters 3 and 6a. In Chapter 4 we demonstrate that X-ray absorption near edge spectroscopy (XANES) directly probes molecular orbitals. The negative second derivative of these XANES data provides direct information on the energy and charge distribution within the different molecular orbitals. The corresponding orbital interaction diagrams are determined. Theoretical density functional and FEFF8 calculations validate the results obtained. The XANES spectroscopy technique described can be applied to in principle every kind of sample. The introduction of substituents at the para-position of the NCN-pincer ligand benzene ring allows one to tune the metal center of the complex electronically and consequently the reactivity of the catalytically active pincer. In Chapter 5 we have used the Atomic XAFS contributions in the Pt L2,3 XAFS spectra of [PtCl(NCN)-Z] pincer complexes to probe the electron density changes on the Pt atom. The results validate the AXAFS technique and the AXAFS theoretical interpretation in particular. Theoretical FEFF8 calculations predict the proper effects and trends. AXAFS is thus a powerful technique to probe the electronic properties of Pt and principally, of every atom, similar yet complementary to NMR. Moreover, XAFS measurements can be performed in situ and time-resolved so the changes in electronic properties can be monitored during reaction. The novel time-resolved ED-XAFS/UV-Vis set-up was used to elucidate the deactivation pathway of palladium catalysts and to gain insights into the catalytic cycle of a copper catalyzed amination reaction. In Chapter 6b, the size and nature of the different inactive Pd-clusters formed during the allylic substitution reaction as a function of ligand and solvent are studied in detail. In Chapter 7 it is shown that the application of a wide range of spectroscopic techniques gives detailed structural and electronic information on the reaction intermediates involved in the Cu(II)-catalyzed arylation reaction. In combination with catalytic results, a novel, unexpected reaction mechanism for this important Cu(II) catalyzed arylation of aza-compounds has been proposed
Montenegro and NATO membership:An achievement and a risk?
No full textMontenegro will join NATO as the 29th member of the Trans-Atlantic Alliance. That is now a fact, following the recent ratifications of the United States, the Netherlands and Spain, and on 28 April that of the Montenegrin parliament.[1] What do we know about this small country in the Western Balkans, with a population of less than 700,000, that declared its independence in 2006? Nevenka Tromp of the University of Amsterdam analyses Montenegro's history and road towards independence, its internal political developments since and the process of Montenegro’s Euro-Atlantic integration
Montenegro and NATO membership: An achievement and a risk?
No full textMontenegro will join NATO as the 29th member of the Trans-Atlantic Alliance. That is now a fact, following the recent ratifications of the United States, the Netherlands and Spain, and on 28 April that of the Montenegrin parliament.[1] What do we know about this small country in the Western Balkans, with a population of less than 700,000, that declared its independence in 2006? Nevenka Tromp of the University of Amsterdam analyses Montenegro's history and road towards independence, its internal political developments since and the process of Montenegro’s Euro-Atlantic integration
The Journal of Maarlen Harperlszoon Tromp, anno 1639, traduit et publié par G. R. Boxer, 1930
No full textAndré Louis. The Journal of Maarlen Harperlszoon Tromp, anno 1639, traduit et publié par G. R. Boxer, 1930. In: Revue d'histoire moderne, tome 5 N°27,1930. p. 235
Mapping Transition Readiness: A model for identifying how and where design can intervene in system transi-tions
No full textDesigners are increasingly tackling complex societal challenges and fostering system transitions. Transitions are long-term, multi-level, multi-phasal system changes involving numerous actors, requiring innovations that develop new relationships within the system. Therefore, the process of designing for transitions requires new ways of bridging system analysis and system synthesis. This paper explores the concepts of ‘transition readiness’ and ‘value conflicts’ as valuable indicators to bridge this gap and support designers in fos-tering system transitions. Synthesizing insights from literature and previous experience, we propose a first step towards an integrative model for mapping a system transition in a way that inspires design. Our model, called the Transition Readiness Profiles, anticipates the dynamics of a system transition and helps identify how and where design can inter-vene to accelerate the transition. It analyzes the transition at the individual-, organization-, and system level to understand the system dynamics and reveal what organizations can bring forward to foster the transition relative to others. The Profiles capture the relational dimension of a transition by mapping readiness, value conflict, and stakeholder relation-ships and dependencies.Design Aesthetic
Nicholas J. Tromp. Primitive Conceptions of Death and the Nether World in the Old Testament
No full textCaquot André. Nicholas J. Tromp. Primitive Conceptions of Death and the Nether World in the Old Testament . In: Revue de l'histoire des religions, tome 178, n°2, 1970. pp. 206-207
Nicholas J. Tromp. Primitive Conceptions of Death and the Nether World in the Old Testament
No full textCaquot André. Nicholas J. Tromp. Primitive Conceptions of Death and the Nether World in the Old Testament . In: Revue de l'histoire des religions, tome 178, n°2, 1970. pp. 206-207
n Model om kooperatiewe onderwys in handelswetenskappe aan technikons te implementeer
No full textProefskrif (Ph. D.) -- Universiteit van Stellenbosch, 1990.Full text to be digitised and attached to bibliographic record
S. P. C. Tromp, S. J., De Romanorum piaculis, specimen litterarium inaugurale... pro gradu doctoratus... in Universitate Amstelodamensi...
No full textChapot Victor. S. P. C. Tromp, S. J., De Romanorum piaculis, specimen litterarium inaugurale... pro gradu doctoratus... in Universitate Amstelodamensi.... In: Revue des Études Anciennes. Tome 25, 1923, n°4. pp. 398-399
Validation of design for value in social design projects: Presentation of a Value Validation Framework to assess the realisation of values in social design projects, supporting a more profound design for value process
No full textAnno 2021, designers engage with questions of increasing complexity and impact. Designers are involved in creating services and systems that reach beyond an individual user, ultimately reshaping society. This realisation motivates the question of how designers should deal with the accompanying responsibility. The domain of Design for Values (van den Hoven et al., 2015) encourages conscious innovation with the call for a deliberate design for values and advocates a thoughtful stance towards the creation of artefacts. As social design is concerned with societal well-being and commitment to design for the common good (Tromp, Hekkert, 2017), it is regarded as a specificity of Design for Values. This thesis opens up the conversation of impact in social design practices by researching how designing for values is validated within social design projects. Although the mission for conscious design is vital, frameworks to assess the adequate operationalisation of values are lacking, and impact methodology in the field of social design is fairly under developed. Hence, measures to guarantee value manifestation and safeguard engagement with claims made are missing. For this reason, both domains of Design for Values and social design will be enhanced by a framework that supports assessing the design for value, as a result enabling validation of value realisation within design projects. The Value Validation Framework introduced in this thesis presents the structure of reasoning towards a valid value claim. It is argued that to make a valid claim, designers must specify their value claim in terms of effects on behaviour, substantiate a claim with proper evidence and provide justification for these specifications. This ensures construct validity for the claim being made and above all, that designers discern what they are factually achieving. As a result, the framework administers a critical stance towards the impact that can be ascribed to projects. First, the Value Validation Framework was constructed out of theoretical models enriched with qualitative data from an explorative study among professionals. This framework enabled to assess social design projects and was used in the second part of this thesis, the case study research. In this study, five social design projects are assessed concerning the validity of their claim to realise a particular value with their design. The study provided an increased understanding of how designers structure their design projects and this information was used in the third part of this thesis. In which the analysis was used to reflect on ways to make valid value claims. Social designers involved in the case study research endorse the unique perspective that the Value Validation Framework provides and emphasise that the conducted analysis has provided a meaningful assessment of their social design projects. A commitment to value claim validation provides an opportunity for social designers to enhance their considerations of effect and focus on the substantial impact they accomplish. As a result, contributing to a renewed perspective on how they can enhance their design project and fundamentally commit to a better world.Design for Interactio
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