Universiteit Leiden

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Lecture

This Week’s Discoveries | 9 April 2019

Date
Tuesday 9 April 2019
Time
Location
Oort
Niels Bohrweg 2
2333 CA Leiden
Room
De Sitterzaal

First lecture

Title
Catching elusive glycosyl cations as intermediate in the glycosylation reaction

Speaker
Thomas Hansen (LIC)
Thomas is a PhD candidate at the Leiden Institute of Chemistry (LIC) in the bio-organic synthesis group, where he works on various topics on the interface between organic chemistry and computational chemistry.

Abstract
Carbohydrates are involved in numerous crucial biological processes. Unravelling the roles of these complex molecules requires synthetic, well-defined, pure glycostructures. Unfortunately, the synthesis of these constructs continues to be a major challenge, because we still do not properly understand how two carbohydrate building blocks can be fused together, as a result of the complexity of the glycosylation reaction. Glycosyl cations are key reactive intermediates in the glycosylation reaction but given their high flexibility, reactivity and fleeting nature these species remain poorly understood. We have developed a computational method to capture the reactivity of these species as a function of their overall shape, taking into account the full conformational space that is at their disposal, and have built a model that quantitatively predicts the stereochemical outcome of their reactions. The fundamental insight offered by the calculations into the structure and reactivity of the cations will result in improved glycosylation chemistry, enabling the more effective generation of oligosaccharides to fuel glycobiology and glycobiotechnology research.

Second lecture

Title
Sustainable design of emerging photovoltaic technologies

Speaker.
Carlos Felipe Blanco (CML)
Carlos obtained his Master’s degree in Industrial Ecology at Leiden University. Currently, he is a PhD student at the Institute of Environmental Sciences CML. His research focuses on probabilistic methods for the sustainability assessment of technologies at early research & development stages. These methods are used to guide technology developers towards more sustainable designs and to inform the prioritization of future research efforts.

Abstract
Multijunction III-V photovoltaic cells, which have achieved record conversion efficiencies above 33%, are now looking like a promising option to replace conventional silicon cells in future PV markets. As efforts to increase efficiency and reduce cost are gaining important traction, it is of equal importance to understand whether the manufacturing methods and materials used in these cells introduce undesired environmental trade-offs. We investigate this for two III-V cell concepts using state of the art life-cycle assessment methods. Considering that the proposed III-V technologies are still relatively immature, we use probabilistic methods to account for uncertainties in the extrapolation of lab-based data to more industrially relevant processes. Our results show that even at this early stage, and in light of important modelling uncertainties, the III-V PV systems are well positioned to outperform the incumbent silicon PV systems in terms of life-cycle environmental impacts.

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