Experimental models for assaying microvascular endothelial cell pathophysiology in stroke

It is important to understand the molecular mechanisms underlying neuron death following stroke in order to develop effective neuroprotective strategies. Since studies on human stroke are extremely limited due to the difficulty in collecting post-mortem tissue at different time points after the onset of stroke, brain ischaemia research focuses on information derived from in-vitro models of neuronal death through ischaemic injury [1]. This review aims to provide an update on the different in-vitro stroke models with brain microvascular endothelial cells that are currently being used. These models provide a physiologically relevant tool to screen potential neuroprotective drugs in stroke and to study the molecular mechanisms involved in brain ischaemia.     

Anatomy of a laminar starting thermal plume at high Prandtl number

We present an experimental study of the dynamics of a plume generated from a small heat source in a high Prandtl number fluid with a strongly temperature-dependent viscosity. The velocity field was determined with particle image velocimetry, while the temperature field was measured using differential interferometry and thermochromic liquid crystals. The combination of these different techniques run simultaneously allows us to identify the different stages of plume development, and to compare the positions of key-features of the velocity field (centers of rotation, maximum vorticity locations, stagnation points) respective to the plume thermal anomaly, for Prandtl numbers greater than 10³. We further show that the thermal structure of the plume stem is well predicted by the constant viscosity model of Batchelor (Q J R Met Soc 80: 339–358, 1954) for viscosity ratios up to 50.     

Toward multipurpose NMR experiments

Standard phase cycled NMR pulse sequences were generalized such that for each individual step of the pulse phase cycle the free induction decay is stored separately without phase correction. This is in contrast to the usual practice, where pulse responses are phase shifted immediately (by applying a ‘receiver phase’) and co‐added as they are stored. The approach used here allows one to extract different types of NMR information, which are usually referred to as different ‘experiments’, from the same raw data set a posteriori by using complex linear combinations. Storing the free induction decays of individual phase cycle steps separately and using specific linear combinations of these data to obtain a particular type of information increase the overall efficiency of a given set of NMR experiments substantially, because all information can be derived from a single multiplexed data set. This ‘super‐experiment’ requires only as much time as the most complex of the derived specific experiments alone. The principle of this multipurpose approach was demonstrated by performing different multiple‐quantum filtered COSY experiments. It also becomes possible to generate linear combinations, which differ from the conventionally acquired spectra a posteriori. For example, we implemented diagonal peak reduction by using zero‐ and single‐quantum filtered COSY contributions without requiring additional experiment time. Copyright © 2009 John Wiley & Sons, Ltd.     

Towards functional nanostructures: Ionic self-assembly of polyoxometalates and surfactants

Major recent advances in the field of POM-surfactant ISA complexes are the extension of the studies into both thermo- and lyotropic phase behaviour, and the use of the vesicle motif for the production of novel hybrid vesicle structures. The use of metal-coordinating functional surfactants has led to the expression of synergistic functionality in POM-based materials.