IJS KOLOKVIJ, Sreda, 26. 10. 2016; ob 13. uri; prof. dr. Francesc Sagués

[Tanja Debevec]

Vabimo vas na 6. predavanje iz sklopa "Kolokviji na IJS" v letu 2016/17, ki bo v sredo, 26. oktobra 2016, ob 13. uri v Veliki predavalnici Instituta »Jožef Stefan«  na Jamovi cesti 39 v Ljubljani. Napovednik predavanja najdete tudi na naslovu http://www.ijs.si/ijsw/Koledar_prireditev, posnetke preteklih predavanj pa na http://videolectures.net/kolokviji_ijs. 

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prof. dr. Francesc Sagués

Univerza v Barceloni, Barcelona, Španija

 

Aktivni nematiki na površinah

 

Aktivni tekoči kristali so nova vrsta mehkih snovi, za katere vlada v zadnjem času zelo veliko zanimanje. Rekonstituirane suspenzije citoskeletnih filamentov skupaj s proteinskimi motorji so se npr. pokazale kot izvrsten sistem za kvantitativne raziskave izvora znotrajcelične organizacije. Tu mislimo na sistem, razvit v skupini Z. Dogica (Univerza Brandeis): tega tvori sveženj mikrotubulov s kinezinskimi molekularni motorji, ki jih napaja ATP. Osredotočili se bomo na dvorazsežne preparate, za katere je značilna nematska tekstura in hidrodinamični tok, ki je lahko bodisi dokaj urejen bodisi navidez kaotičen. Predstavili bomo različne scenarije obnašanja tega aktivnega nematskega sistema v odvisnosti od okolne kapljevine. V najenostavnejšem primeru je sistem v stiku z izotropnimi olji različnih viskoznosti in tu lahko ocenimo doslej neznano strižno viskoznost nematske plasti. Še bolj zanimiva  je situacija, kjer je pasivna okolna kapljevina kar tekoči kristal v  smektični fazi, ki omogoča povsem nove strategije nadzora aktivega toka. Na kratko se bomo dotaknili tudi drugih scenarijev, značilnih za enkapsulirane aktivne nematike v stiku z izotropnimi in anizotropnimi olji.

Predavanje bo v angleščini.

Lepo vabljeni!

 

 

 




We invite you to the 6th Institute colloquium in the academic year 2016/17. The colloquium will be held on Wednesday October 26, 2016 at 1 PM in the main Institute lecture hall, Jamova 39, Ljubljana. To read the abstract click  http://www.ijs.si/ijsw/Koledar_prireditev. Past colloquia are posted on  http://videolectures.net/kolokviji_ijs.

 

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prof. dr. Francesc Sagués

Universitat de Barcelona, Barcelona, Spain

 

Active nematics at interfaces

 

 

Active liquid crystals are a new class of soft materials that have recently raised a huge interest. In particular, reconstituted suspensions of cytoskeletal filaments and associated motor proteins have proven ideal for quantitative studies of the origin of subcellular organization. Here we refer to the system initially engineered by the group of Z. Dogic (Brandeis University), consisting of bundled microtubules powered by ATP-fueled kinesin motors. We concentrate on two-dimensional preparations showing nematic textures and streaming flows, from largely-organized to seemingly chaotic. We will present results on different scenarios where this active nematics system is conditioned with interfacial fluids. The simplest situation corresponds to prepare them in contact with isotropic oils of different viscosities. >From this we can extract a prediction for the as of now unknown shear viscosity of the nematic film. More striking is the situation when the contacting passive fluid is a liquid crystal in its smectic phase. In this latter situation a totally unprecedented strategy of control of the active flows has been recently demonstrated. Other scenarios corresponding to encapsulated active nematics, both in contact with isotropic and anisotropic oils will be briefly presented.

 

Cordially invited!

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