Internal Seminar: Sowwan Unit and Skoglund Unit

Join us for November's 1st Internal Seminar Series, from 17:00 to 18:00 in C210. This month's seminars feature the Nanoparticles by Design Unit (Ibrahim Mukhles Sowwan) and the Structural Cellular Biology Unit (Ulf Skoglund).

Nanoparticles by Design Unit (Ibrahim Mukhles Sowwan)

Speaker : Dr. Sushant Kumar

Title : Mg/Pd based novel nano-portal structure for controlled hydride formation

Abstract : Hydrogen energy has been the topic of extensive research in past few decades. Owing to its high specific energy content and ability to provide clean energy, hydrogen has been considered as a preferred alternative to fossil fuels. Besides the challenge of producing clean hydrogen itself, other major issue is the lack of a proper storage material. In this regard, magnesium and Mg-based material systems are considered as promising candidates. However, these materials are known to be thermodynamically as well as kinetically limited. To study the hydride formation in a controlled way, we have designed a novel nano-portal structure of Pd nanoparticles deposited on Mg film, by which the hydride will nucleate only under Pd nanoparticles. Hydrogen ab (de-)sorption study was done at different temperature and pressure conditions using Setaram PCTpro2000. The experimental results illustrate that Pd nanoparticles (average size ~5nm) when deposited on 3 µm thick Mg film exhibited fast absorption kinetics compared to the pristine Mg film. Moreover, we also investigated the reaction mechanism with aid of ETEM and SEM. The hydride growth in this nano-portal structure is dominated by the three-dimensional nucleation and growth (fitted by the 3D contracting-volume model), and the overall reaction rate was limited by hydrogen diffusion in the as-grown hydride. Further, we employed selected area electron diffraction (SAED) technique to study in-situ hydrogen desorption at different temperature for the nano-portal structure.

Structural Cellular Biology Unit (Ulf Skoglund)

Speaker : Prof. Ulf Skoglund

Title : Visualizing individual protein molecules in 3D with Molecular Electron Tomography

Abstract : Three-dimensional (3D) visualization of individual protein conformations can be a powerful way to understand protein function and large-scale molecular dynamics under various conditions, i.e. how each individual macromolecule is moving around in its environment. Today this has become possible to accomplish by using the molecular electron tomography procedure. Using specimen recordings from a large number of viewing angles in a transmission electron microscope, a 3D reconstruction of a selected volume of the specimen can be calculated. Algorithms that our research unit is developing allow the 3D reconstructions to be calculated at around 2-nm resolution for proteins in fast-frozen buffer solutions. As a result, we can establish the conformational space for a given macromolecule by inspection of its various conformations as they appear in 3D. Thus individual macromolecules can be examined for their conformational flexibility, subunit assembly and tendency to deviate from a perhaps known X-ray crystallographic structure. In this Unit we have developed all the aspects of the method we are using including the experimental procedures for working with the electron microscopes as well as practical user interfaces to our software.