List of Events

MRSEC SEMINARS-EVENTS

MRSEC Seminars are normally held at 4:00 p.m. in Abelson 229, unless otherwise noted. Find Abelson-Bass-Yalem building on the interactive map.

 



December 1, 2016
Room: Abelson 229
Time: 4 p.m.
Event: MRSEC Seminar
Speaker: Slaven Garaj, National University of Singapore
Title: Nanofluidics with graphene membranes
Abstract: Graphene’s unique interaction with water, ions and molecules implies its superior performance in diverse application such as next-generation DNA sequencing1 or filtration2. Water flows unhindered over sp2-derived surfaces of carbon nanotubes3 and graphene nanochannels4, similar to some biological membrane pores. Another model system revealing such behavior is the graphene-oxide (GO) membrane, consisting of stacked layers of graphene sheets, sporting a percolated network of pristine graphene channels delimited by chemical functional groups. We investigated – within nanometer-high graphenic channels of GO – mobility of a wide selection of aqueous salts ions. Two general trends were revealed: (a) cation permeability decreases exponentially with increased hydration radius; and (b) permeability of negatively charged ions is suppressed by order of magnitude compared to positive ions of similar radius. We conclude that the dominant mechanisms for the ion rejection in GO membranes are size exclusion due to compression of the ionic hydration shell in narrow channels, and electrostatic repulsion due to membrane surface charge. Armed with the insight into the physical mechanism governing the ionic flow, we were able to engineer new membranes with decreased the ionic cut-off size and increased charge selectivity; all leading to promising applications in desalination and electrodialysis.


1.       Garaj, S. et al. Graphene as a subnanometre trans-electrode membrane. Nature 467, 190–193 (2010).
2.       Cohen-Tanugi, D. & Grossman, J. C. Water Desalination across Nanoporous Graphene. Nano Lett 12, 3602–3608 (2012).
3.       Hummer, G., Rasaiah, J. C. & Noworyta, J. P. Water conduction through the hydrophobic channel of a carbon nanotube. Nature 414, 188–190 (2001).
4.       Radha, B. et al. Molecular transport through capillaries made with atomic-scale precision. Nature 538, 222–225 (2016).





December 9, 2016
Room: Abelson 229
Time: 2:30 p.m.
Event: IRG 1
Speaker: Guillermo Rodriguez Lazaro, Hagan Lab Postdoc
Title: Mechanisms of virus assembly on membranes 
Abstract: Many viruses have an envelope covering and protecting the nucleocapsid, a protein shell that contains the viral genome. Some enveloped viruses assemble directly on the cell membrane, including alphavirus and flavirus (eg Chikunguya and Zika viruses, respectively). These viruses typically consist of the nucleocapsid, and an outer layer consisting of lipid membrane and viral transmembrane glycoproteins. Despite extensive experimental efforts to understand the lifecycle of enveloped viruses, their assembly pathways and the factors which control budding remain poorly understood. For example, it remains an open question whether the nucleocapsid assembles on the cell membrane concomitant with budding, or whether the nucleocapsid first assembles in the cytoplasm and then subsequently buds through the cell membrane. Resolving this question has been challenging due to the lack of controllability within cells and the transient nature of assembly intermediates. Therefore, we have developed a coarse-grained model for viral proteins and the cell membrane, with which we aim to compare these two possible budding pathways.  In particular, we plan to characterize how membrane properties such as rigidity and domain structure affect assembly timescales and particle morphologies for each case, to identify the main barriers which need to be overcome on either pathway, and to determine if one mechanism is more robust to variations in parameters than the other. In this talk, I will describe our current progress toward this goal.





December 9, 2016
Room: Rosenstiel Penthouse
Time: 5:30 p.m.
Event: TacoCat Social
*Grad students and postdocs only*







December 14, 2016
Room: Abelson 229
Time: 2:30 p.m.
Event: IRG 2







December 19, 2016

Room: Abelson 307
Time: 9:30 a.m.
Event: MRSEC Executive Committee

 
January 13, 2016
Room: Rosenstiel Penthouse
Time: 5:30 p.m.
Event: TacoCat Social
*Grad students and postdocs only*
February 10, 2016
Room: Rosenstiel Penthouse
Time: 5:30 p.m.
Event: TacoCat Social
*Grad students and postdocs only*
March 10, 2016
Room: Rosenstiel Penthouse
Time: 5:30 p.m.
Event: TacoCat Social
*Grad students and postdocs only*
April 14, 2016
Room: Rosenstiel Penthouse
Time: 5:30 p.m.
Event: TacoCat Social
*Grad students and postdocs only*
May 12, 2016
Room: Rosenstiel Penthouse
Time: 5:30 p.m.
Event: TacoCat Social
*Grad students and postdocs only*