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This Week’s Discoveries | 27 September 2016

Tuesday 27 September 2016

First Lecture

Title: Living Lab: studying eco(toxico)logical impacts within the field situation
Speakers: Martina Vijver en Henrik Barmentlo (CML)
Martina is an associate professor of ecotoxicology in the department of Conservation Biology at CML. Henrik is a PhD student is her group who studies the impact of chemical induced effects on aquatic communities in the field.

In spite of years of research, there remains a large knowledge gap on the actual effects of chemical compounds in our natural waters. To date, the effects of chemical compounds are mostly tested in simple laboratory setups in a controlled environment. While this is an easy and quick way of determining compound effects, it is endlessly less complex than our natural environment. This complexity might actually alter the toxicity of chemical compounds. Therefore, it is not possible to fully assess the hazard of chemicals in our environment by a laboratory setup. The Living Lab will be 36 ditches, each with a length of 10 meters located on an extension of the Bio Science Park in Leiden. These ditches will be exposed to different combinations of chemical compounds used in agriculture, such as nutrients and pesticides. The great benefit of this setup is that the chemical compounds can be tested under real natural conditions.

Second Lecture

Title: The melting of electrons in Mott insulators: universality, order, pseudogap
Speaker: Milan Allan (LION)

Milan is an assistant professor in the Quantum Matter & Optics group at LION. His goal is to explore and understand new quantum states of electronic matter on the atomic scale. To do so, his group uses and develops novel spectroscopic-imaging scanning tunneling microscopy (SI-STM) tools to visualize the relevant quantum mechanical degrees of freedom.

Some materials carry an electrical current more easily than others. Metals are for example world class conductors. Inside them, the electrons form an electronic liquid that flows through the atomic lattice. In specific insulators on the other hand, electrons are stuck to their place in the lattice; the electronic liquid is frozen. In these so-called Mott insulators, one can replace some atoms with different ones. This is called ‘doping’. It is known that doping leads to a melting of the frozen electronic liquid, but nobody knows how this process works. Milan together with PhD students Irene Battisti and Koen Bastiaans have, for the first time, visualized this melting process in a family of materials called iridates. They discovered that the melting process is very inhomogeneous, with puddles forming in between frozen areas. These puddles are only a few nanometers in size. In collaboration with theoretical physicist Jan Zaanen, they published their results last week, September 19 in the on line edition of Nature Physics.


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