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DTSTAMP:20260425T092615Z
UID:6319a32f306ac573646179@ist.ac.at
DTSTART:20230223T110000
DTEND:20230223T120000
DESCRIPTION:Speaker: Chantal Valeriani\nhosted by Jérémie Palacci\nAbstra
 ct: Active matter systems are composed of constituents\, each one in noneq
 uilibrium\, that consume energy in order to move [1]. A characteristic fea
 ture of active matter is collective motion leading to nonequilibrium phase
  transitions or large scale directed motion [2].A number of recent works h
 ave featured active particles interacting with obstacles\, either moving o
 r fixed [3\,4\,5]. When an active particle encounters an asymmetric obstac
 le\, different behaviours are detected depending on the nature of its acti
 ve motion.On the one side\, rectification effects arise in a suspension of
  run-and-tumble particles interacting with a wall of funnelled-shaped open
 ings\, caused by particles persistence length [6]. The same trapping mecha
 nism could be responsible for the intake of microorganisms in the undergro
 und leaves [7] of Carnivorous plants [8].On the other side\, for aligning 
 particles [9] interacting with a wall of funnelled-shaped openings\, trapp
 ing happens on the (opposite) wider opening side of the funnels [10\,11].I
 nterestingly\, when funnels are located on a circular array\, trapping is 
 more localised and depends on the nature of the Vicsek model. Active parti
 cles can be synthetic (such as synthetic active colloids) or alive (such a
 s living bacteria). A prototypical model to study living microswimmers is 
 P. fluorescens\, a rod shaped and biofilm forming bacterium. Biofilms are 
 microbial communities self-assembled onto external interfaces. Biofilms ca
 n be described within the Soft Matter physics framework [12] as a viscoela
 stic material consisting of colloids (bacterial cells) embedded in a cross
 -linked polymer gel (polysaccharides cross-linked via proteins/multivalent
  cations)\, whose water content vary depending on the environmental condit
 ions. Bacteria embedded in the polymeric matrix control biofilm structure 
 and mechanical properties by regulating its matrix composition. We have re
 cently monitored structural features of Pseudomonas fluorescens biofilms g
 rown with and withouthydrodynamic stress [13\,14]. We have demonstrated th
 at bacteria are capable of self-adapting to hostile hydrodynamic stress by
  tailoring the biofilm chemical composition\, thus affecting both the meso
 scale structure of the matrix and its viscoelastic properties that ultimat
 ely regulate the bacteria-polymer interactions.REFERENCES[1] C. Bechinger 
 et al. Rev. Mod. Phys. 88\, 045006 (2016)[2] T. Vicsek\, A. Zafeiris Phys.
  Rep. 517\, 71 (2012)[3] C. Bechinger\, R. Di Leonardo\, H. Lowen\, C. Rei
 chhardt\, G. Volpe\, and G.Volpe\, Reviews of Modern Physics 88\, 045006 (
 2016)[4] R Martinez\, F Alarcon\, DR Rodriguez\, JL Aragones\, C Valeriani
 The European Physical Journal E 41\, 1 (2018)[5] DR Rodriguez\, F Alarcon\
 , R Martinez\, J Ramrez\, C Valeriani\, Soft matter 16 (5)\, 1162 (2020)[6
 ] C. O. Reichhardt and C. Reichhardt\, Annual Review of Condensed MatterPh
 ysics 8\, 51 (2017)[7] W Barthlott\, S Porembski\, E Fischer\, B Gemmel Na
 ture 392\, 447 (1998)[8] C B. Giuliano\, R Zhang\, R.Martinez Fernandez\, 
 C.Valeriani and L.Wilson (in preparation\, 2021)[9] R Martinez\, F Alarcon
 \, JL Aragones\, C Valeriani Soft matter 16 (20)\, 4739 (2020)[10] P. Gala
 jada\, J. Keymer\, P. Chaikin and R.Austin\, Journal of bacteriology\,189\
 , 8704 (2007).[11] M. Wan\, C.O. Reichhardt\, Z. Nussinov\, and C. Reichha
 rdt\, PhysicalReview Letters 101\, 018102 (2008).[12] J N. Wilking \, T E.
  Angelini \, A Seminara \, M P. Brenner \, and D A. Weitz MRS Bulletin 36\
 , 385 (2011)[13]J Jara\, F Alarcn\, A K Monnappa\, J Ignacio Santos\, V Bi
 anco\, P Nie\, M Pica Ciamarra\, A Canales\, L Dinis\,I Lpez-Montero\, C V
 aleriani\, B Orgaz\, Frontiers in microbiology 11\, 3460 (2021)[14] P Nie\
 , F Alarcon\, I Lpez-Montero\, B Orgaz\, C Valeriani\, M Pica CiamarraSoft
  Material\, 0\, 1 (2021)
LOCATION:Big Seminar Room B (big) 63 seats (I23.EG.102)\, ISTA
ORGANIZER:cpetz@ist.ac.at
SUMMARY:Chantal Valeriani: Trapping active particles up to the limiting cas
 e: bacteria enclosed in a biofilm
URL:https://talks-calendar.ista.ac.at/events/3993
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