Two QLS guest seminars - Monday, 9 September

[Quantitative Life Sciences]

Two QLS Guest Seminars - Monday, 9 September 11h00am and 12h00

ICTP, Central Area, 2nd floor, SISSA Building, via Beirut 2


At 11h00

Speaker: Michael Shats - Research School of Physics, The Australian 
National University, Canberra, Australia


Title: Controlling active spinners using vortex lattices

Abstract:
Actively spinning particles attracted much attention in recent years, 
mostly from a point of view of their ability to self-assemble on the 
liquid surface. On the other hand, the control of surface flows using 
surface waves has led to interesting analogies with optical traps for 
microparticles and ultracold atoms. In this talk I will present recent 
experiments on the confinement of active spinners within a wave-driven 
vortex lattice, also referred to as liquid metamaterial. I will discuss 
properties of the surface flow generated by two orthogonal standing 
waves. The spinners can be efficiently manipulated in such a flow to 
either occupy stationary orbits within a metamaterial cell, or they can 
be moved between the cells. I will discuss forces acting on the spinners 
in such flows and will show how multiple spinners interact to form 
stable self-organised configurations.

Indico: http://indico.ictp.it/event/9054/


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At 12h00

Speaker: Hua Xia - Research School of Physics, The Australian National 
University, Canberra, Australia


Title: Control of bacteria attachment and biofilm growth using surface waves

Abstract:
Surface adherent microbial consortia, biofilm growth, is a predominant 
growth mode for bacteria and other microorganisms in nature. While there 
is considerable literature related to the negative aspects of the 
biofilms including chronic infections and industrial biofouling, they 
can also be harnessed as biotechnological tools such as in waste water 
treatment and remediation of environmental pollutions.

We are interested in identifying fluid conditions favouring or 
discouraging bacteria attachment and formation of biofilms and 
evaluating the role of the surface waves and vibration in the biofilm 
formation.

Our results show that the formation of the biofilms is strongly affected 
by the surface wave. Deterministic flows in a thin layer of nutrient 
medium promote the growth of patterned biofilms while chaotic and 
turbulent fluid motion reduces it. The settlement of bacteria and the 
locations of biofilms differ from the sedimentation patterns of inactive 
bacteria and of the passive microparticles, suggesting that the 
environmental factors dominate over hydrodynamic advantages. Wave-driven 
flows control the delivery routes of nutrients, oxygen and of the 
bacteria communication agents thus allowing to shape the biofilm 
development and to control macroscopic biofilm patterns. The results 
offer efficient tools to encourage or discourage the attachment of 
bacteria and allow shaping the biofilms using low-frequency waves.

Indico: http://indico.ictp.it/event/9055/




Everyone interested is most welcome to attend!

-- 
Erica Sarnataro
Group Secretary
Quantitative Life Sciences
The Abdus Salam International Centre for Theoretical Physics (ICTP)
Trieste,  Italy
Tel. +39-040-2240623
www.ictp.it/research/qls.aspx
e-mail: qls at ictp.it