High-resolution imaging of the human amygdala : role of basolateral and centromedial complexes in reward processing and associative learning .

THESIS 9793The amygdala is an inherently heterogeneous aggregation of nuclei. Although the animal literature has revealed some segregation of function within these nuclei, it has not been possible to investigate the role of human amygdalar subregions to date due to limitations in the spatial resolution of fMRI

Solubilisation of Oils of Different Polarity in Aqueous Solutions of Pluronic Triblock Copolymers

Abstract The micellisation behaviour of Pluronic F108 was studied as a function of the addition of various more or less polar additives, such as hexanol, geraniol, toluene, methyl heptanoate, polyproylene oxide (PPO), and nitropropane. It is observed that the critical micellisation temperature (CMT) is substantially reduced upon the solubilisation of most of the additives (but not for methyl heptanoate and PPO) and at the same time the concomitant enthalpy of micellisation becomes larger. Both changes in CMT and enthalpy of micellisation are linear with respect to the concentration of additive. The pronouncedness of this effect is related to the polarity of the additive (as characterised for instance by its water solubility) and for instance similar effects are achieved for much smaller amounts of geraniol compared to hexanol. The structural evolution of the Pluronic solutions upon addition of the additives was also followed by SANS experiments and show that relatively small amounts of added solubilisate can have a very pronounced effect on the extent of the micellisation and size of the aggregates formed, i.e., effectively lowering the CMT by rendering the amphiphilic system more hydrophobic and especially the medium chain alcohols show pronounced synergism.</jats:p

Small Angle Neutron Scattering, X ray Diffraction, Differential Scanning Calorimetry, and Thermogravimetry Studies to Characterize the Properties of Clay Nanocomposites

Nanocomposites based on laponite RD and (ethylene oxide)98(propylene oxide)67(ethylene oxide)98 (F127)triblock copolymer or poly(ethylene) glycol 2000 (PEG2000) were prepared by using the melting method. Small-angle neutron scattering and the X-ray diffraction experiments provided insights into the organization of the laponite RD dispersed in the macromolecular matrix over a wide length scale. SANS data analysis by means of a fractal law evidenced the formation of clusters of laponite RD at long correlation distance. The single laponite RD particles and the lamellar structure of F127 were described in the shorter length scale. Finally, the crystalline structure of the macromolecule was observed for very short length scales. Differential scanning calorimetry measurements con\ufb01rm that the macromolecule anchored to the laponite RD surface is amorphous, in agreement with the XRD \ufb01ndings, and allowed to determine amount and thickness of the adsorbed macromolecule layer. The mesoscopic structure of the nanocomposites is straightforwardly correlated with the macroscopic properties (thermal stability, crystallization), which are crucial in the application areas. Namely, the different effect played by the nano\ufb01ller on the thermal stability of F127 and PEG2000 was correlated to the laponite RD cluster size. Accordingly, the thermal stability of the nanocomposites is enhanced if the clusters have a smaller size. As concerns the crystallization, the clusters were invoked as responsible for the observed retardation of the growth of the crystalline domains due to an increased diffusion energy barrier that slows down the macromolecule mobility

Poly NIPAM Microgels with Different Cross Linker Densities Scaling Behavior of the Network Fluctuations in the Vicinity of the Volume Phase Transition

Thermoresponsive microgel particles made of the monomer N isopropylacrylamide NIPAM and the cross linker molecule N,N methylenebisacrylamide BIS were synthesized using three different cross linker molar ratios. The volume phase transition behavior of these colloids was investigated by means of dynamic light scattering DLS and small angle neutron scattering SANS covering the different length scales of interest. Both methods provide the temperature of the volume phase transition in good agreement. The volume change as followed by DLS is described using the Flory Rehner theory, leading to the determination of the spinodal temperature. Furthermore, the network correlation length amp; 958;, which is available from appropriate fits of the measured SANS profiles, was used to study the critical behavior in terms of scaling laws. The results from DLS and SANS show a strong cross linker density dependenc