[seminar] dr. sc. Antonio Šiber @ Institute of Physics, Wednesday December 8th 2021 at 11:00, room ``Mladen Paić", 3rd wing, and Zoom

[Neven Šantić]

Seminar at IF, Wednesday December 8th 2021 at 11:00, room ``Mladen Paić", 3rd wing, and Zoom 

Mechanics of desiccation and swelling of pollen 
Mehanika isušivanja i bubrenja peludi 

dr. sc. Antonio Šiber 
Institut za fiziku, Zagreb 

Join Zoom Meeting: https://zoom.us/j/99770477560 
Meeting ID: 997 7047 7560 


The structure of pollen grains, which is typically characterized by soft apertures in an otherwise stiff exine shell, guides their response to changes in the humidity of the environment. These changes can lead to the desiccation of the grain and its infolding but also to excessive swelling of the grain and even its bursting. Here, we use an elastic model to explore the mechanics of pollen grain swelling and the role that apertures play in this process. Depending on the aperture design, desiccation can lead to regular infolding and termination of further loss of moisture, preserving thus the fertilizing potential of the pollen grain. It is necessary that the elasticity and the geometry of the grain fulfill certain conditions, in order that the grain infolds regularly. The evolutionary path of the plant species is thus determined in part also by the mechanical constraints which the pollen grains must obey. On the other hand, an influx of water in the grain leads to its swelling and possible bursting, and this process also depends on the properties of pollen apertures. As apertures typically occur in allergenic pollen grains, the bursting of such grains is important in the context of human health. 

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Odziv peludnih zrna na promjene vlažnosti u okolini određen je njihovom strukturom koju karakteriziraju mekana područja (aperture) u inače krutoj ljusci. Promjene vlažnosti mogu dovesti do isušivanja zrna i do njihovog umotavanja ili kolapsa, ali i do prekomjernog bubrenja pa čak i pucanja. Elastični model zrna formuliran je i iskorišten da se istraži mehanika umotavanja i bubrenja peludnih zrna te uloge koju u tom procesu igraju aperture. Ovisno o dizajnu apertura isušivanje može dovesti do njihovog regularnog zatvaranja i prestanka daljnjeg gubitka vlage što čuva fertilizacijski potencijal peludnog zrna. No, da bi taj proces uistinu regularno umotao zrno, nužno je da elastičnost i geometrija zrna ispunjavaju određene uvjete. Stoga je evolucijska putanja biljnih vrsta određena i mehaničkim ograničenjima kojima pelud mora udovoljiti. S druge strane, dotok vode u zrno dovodi do njegovog bubrenja pa i mogućeg pucanja, a proces također ovisi o svojstvima peludnih apertura. Kako aperture karakteriziraju i alergenu pelud koju raznosti vjetar, pucanje je takve peludi važno i u kontekstu ljudskog zdravlja. 

Seminar hosts: [ mailto:balog at ifs.hr | Neven Šantić ] i [ mailto:ddominko at ifs.hr | Damir Dominko ] 
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Potičemo slušatelje da, zbog epidemiološke situacije, u što većem broju prate seminar ``on-line" putem Zooma. 

Due to the epidemiological situation, we encourage the audience to follow the seminar on-line via Zoom. 


-- 
Dr.sc. Neven Šantić 
Institute of Physics 
Bijenička cesta 46, 10000 Zagreb, Croatia 
phone: +385 1 469 8865 
web: http://cold.ifs.hr 
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