Shape-Persistent Multimetallic Cartwheel Complexes: Design, Catalysis and Recycling

An important new research area in the field of homogeneous catalysis is the development of catalytic processes which combine the advantages of homogeneous (high activity/selectivity, mild conditions, reproducibility, good catalyst description) and heterogeneous catalysis (easy catalyst recycling, low catalyst quantities, high total turnover number (ttn)). A promising approach to achieve this, is by applying nanofiltration technology: adjusted homogeneous catalysts are applied in a membrane reactor and recycled in situ, even allowing catalytic reactions under continuously operating conditions. This leads to a significant increase in the total turnover number of the catalyst. Due to the very small pore-sizes in the membranes, macromolecules with sizes between 0.5 and 8 nanometers can be retained in solution by applying nanofiltration technology. To create homogeneous catalysts which possess the dimensions needed for efficient retainment by nanofiltration membranes, it is necessary to anchor catalytically active transition-metal complexes to soluble macromolecular supports. This thesis describes the design and synthesis of shape-persistent nanosize multi(pincer-metal) complexes containing linear, flat or three-dimensional geometries. In particular, these complexes were studied in a nanofiltration membrane reactor in order to investigate the influences of shape-persistence, dimension and geometry on the retention of these compounds by nanofiltration membranes. Furthermore, these macromolecular complexes were tested as homogeneous catalysts in different organic transformations. One example is given in which a shape-persistent nanosize complex is applied as a homogeneous catalyst in a nanofiltration membrane reactor under continuous reaction conditions. In this research, aromatic supports were chosen for the macromolecular complexes since it assures a high rigidity (shape-persistence) as well as a high inertness toward many reagents, allowing a versatile use as homogeneous catalyst for diverse organic reactions. A further objective of this work was to investigate whether these highly symmetric (C3- or D3-symmetry, as a result of the aromatic backbone and the substitution pattern) macromolecular materials could be used as supramolecular templates in the selective construction of large heterocycles, using olefin metathesis as the ring-closing reaction

Integrated optics sensors for multi-sensing platforms

An overview is presented of research projects on optical sensing, in the Integrated Optical MicroSystems group of the MESA+ Institute for Nanotechnology at the University of Twente

Ischaemic heart disease in Turkish migrants with type 2 diabetes mellitus in The Netherlands: wait for the next generation?

OBJECTIVE: To study the prevalence of ischaemic heart disease in Turkish and Surinam-Asian migrants with type 2 diabetes mellitus in the Netherlands as compared with Europeans. METHODS: In a consecutive case-control study, 59 Turkish and 62 Surinam-Asian patients were compared with 185 Europeans referred to a diabetes clinic for treatment of type 2 diabetes in the period 1992 to 1998. Main outcome measures were ischaemic heart disease and its associated risk factors. RESULTS: The prevalence of ischaemic heart disease was lower (9%) in the Turks (p < 0.02), but higher (29%) in the Surinam-Asians compared with the Europeans (23%). The Turks (52 +/- 10 years) and Surinam-Asians (46 +/- 12 years) were younger than the Europeans (64 +/- 11 years, p < 0.001). Body mass index was 32 +/- 5 (p < 0.001) in the Turks, 27 +/- 5 in the Surinam-Asians (p < 0.05) and 29 +/- 5 in the Europeans. Turkish patients smoked less (23%, p < 0.05) and used less alcohol (4%, p < 0.05) than the Europeans. Proteinuria was found in 24% of the Turks (p < 0.05), 37% of the Surinam-Asians (NS) and 46% of the Europeans. In univariate analysis ischaemic heart disease was related to Turkish origin, OR 0.34 (0.14-0.83) p < 0.02, to Surinam-Asian origin, OR 1.84 (1.00-3.38) p = 0.05, and smoking, OR 1.78 (1.18-2.68) p < 0.01. Other variables were not related to ischaemic heart disease. Multivariate analysis in a model with ethnicity and smoking showed significant relations between ischaemic heart disease and Turkish ethnicity, OR 0.19 (0.06-0.65) p = 0.007, Surinam-Asian origin, OR 2.77 (1.45-5.28) p = 0.002, and smoking, OR 1.79 (1.20-2.66) p = 0.004. CONCLUSION: Type 2 diabetes mellitus in different ethnic groups results in a significant difference in incidence of ischaemic heart disease. The most remarkable finding is a low incidence of ischaemic heart disease in the Turkish patients with type 2 diabetes, independent of smoking. The high prevalence of ischaemic heart disease in young migrant Asians with diabetes is confirmed

Non-Markovian dynamics for an open two-level system without rotating wave approximation: Indivisibility versus backflow of information

By use of the two measures presented recently, the indivisibility and the backflow of information, we study the non-Markovianity of the dynamics for a two-level system interacting with a zero-temperature structured environment without using rotating wave approximation (RWA). In the limit of weak coupling between the system and the reservoir, and by expanding the time-convolutionless (TCL) generator to the forth order with respect to the coupling strength, the time-local non-Markovian master equation for the reduced state of the system is derived. Under the secular approximation, the exact analytic solution is obtained and the sufficient and necessary conditions for the indivisibility and the backflow of information for the system dynamics are presented. In the more general case, we investigate numerically the properties of the two measures for the case of Lorentzian reservoir. Our results show the importance of the counter-rotating terms to the short-time-scale non-Markovian behavior of the system dynamics, further expose the relations between the two measures and their rationality as non-Markovian measures. Finally, the complete positivity of the dynamics of the considered system is discussed

Vergelijking van SMART2SUMO en STONE in relatie tot de modellering van de effecten van landgebruiksverandering op de nutriëntenbeschikbaarheid

Bij de omvorming van landbouw naar natuur is het de vraag welke natuur op de vaak lang bewerkte en overbemeste grond zich zal gaan ontwikkelen en welke beheersmaatregelen de overheid kan treffen om deze natuur een kans te geven. Bij de daarop gerichte scenario-studies wordt voor de voorspelling van de milieukwaliteit gebruik gemaakt van de modellen STONE en SMART2SUMO. STONE is ontwikkeld om op landelijke schaal de uit- en afspoeling van stikstof (N) en fosfor (P) vanuit de landbouw naar grond- en oppervlaktewater te voorspellen, terwijl SMART2SUMO is ontwikkeld om de terrestrische milieukwaliteit (nutriëntenconcentraties en pH in de wortellaag) te voorspellen in bestaande natuur. Om de prestaties van STONE en SMART2SUMO voor de N- en P-modellering voor biodiversiteitsscenario’s te vergelijken, de consistentie te verhogen en waar mogelijk al te verbeteren, zijn beide modellen met elkaar vergleken. Trefwoorden: Landgebruikverandering, modellering, stikstof, fosfaat, natuurontwikkelin

Synthesis and self-assembly of giant porphyrin discs

Contains fulltext : 13852.pdf (publisher's version ) (Open Access