Utrecht University

About: Utrecht University is a education organization based out in Utrecht, Utrecht, Netherlands. It is known for research contribution in the topics: Population & Context (language use). The organization has 58176 authors who have published 139351 publications receiving 6214282 citations. The organization is also known as: UU & Universiteit Utrecht.

A General Method To Coat Colloidal Particles with Silica

Abstract: A general method to coat colloids with silica is described. The amphiphilic, nonionic polymer poly(vinylpyrrolidone) (PVP) was adsorbed to various colloidal particles such as small gold colloids, gold-shell silica-core particles, small and large silver colloids, boehmite rods, gibbsite platelets, and positively or negatively charged polystyrene. After this functionalization the stabilized particles could be transferred to a solution of ammonia in ethanol and directly coated with smooth and homogeneous silica shells of variable thickness by addition of tetraethoxysilane in a seeded growth process. The length of the polymer used strongly influences the stability of the colloids and the homogeneity and smoothness of the initial silica coating. This method is especially useful for colloidal particles that cannot be covered directly with SiO2 by a Stober-like growth process. Compared to methods known from the literature for the coating of such particles, this new method is faster and requires neither the use o...

Efficiency of Functional Brain Networks and Intellectual Performance

Abstract: Our brain is a complex network in which information is continuously processed and transported between spatially distributed but functionally linked regions. Recent studies have shown that the functional connections of the brain network are organized in a highly efficient small-world manner, indicating a high level of local neighborhood clustering, together with the existence of more long-distance connections that ensure a high level of global communication efficiency within the overall network. Such an efficient network architecture of our functional brain raises the question of a possible association between how efficiently the regions of our brain are functionally connected and our level of intelligence. Examining the overall organization of the brain network using graph analysis, we show a strong negative association between the normalized characteristic path length λ of the resting-state brain network and intelligence quotient (IQ). This suggests that human intellectual performance is likely to be related to how efficiently our brain integrates information between multiple brain regions. Most pronounced effects between normalized path length and IQ were found in frontal and parietal regions. Our findings indicate a strong positive association between the global efficiency of functional brain networks and intellectual performance.

Design concepts for the Cherenkov Telescope Array CTA: An advanced facility for ground-based high-energy gamma-ray astronomy

Abstract: Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA.

Complex coacervation of proteins and anionic polysaccharides

Abstract: Coacervation of proteins and anionic polysaccharides is both of practical and theoretical interest. From a large body of literature, it seems that the phase separation is mainly entropically driven, and may most probably be attributed to the delocalisation of the counter ions of the protein and the polysaccharide. The protein and polysaccharide appear to form complexes in solution, which can be viewed as new colloidal entities. These complex particles are neutral and exhibit an attractive interaction, which leads to a phase separation of the gas-liquid type in which a (very) dilute colloidal phase coexists with a very concentrated colloidal phase. In the case of strong poly-acids, usually, a precipitate is formed rather than a liquid coacervate phase. The structure of the concentrated polymer phase seems to resemble a continuous polymer phase in which the protein can diffuse around, as well as the individual polysaccharide molecules. Time scales of diffusion vary from milliseconds to days depending on the strength of the interaction. From a rheological point of view, the concentrated phase is much more viscous than elastic and the rheology resembles the behaviour of a (viscous) concentrated particle dispersion. Theoretical developments are limited probably due to the difficulty to describe the (correlated) charge distribution in the system. There is a strong interest in coacervates for the use of encapsulation. For the same reason, much attention is given to replacing the traditional gelatin by milk and plant proteins.