Yield-stress fluids are soft solids when subjected to a shear stress lower than their yield stress, but flow in response to higher stresses.
I will discuss the process by which Carbopol, a model yield-stress fluid, changes from solid-like to fluid-like when it starts to flow in a
vertical pipe. In a rough-walled pipe, the yielding involves a long transition with several steps: elastic deformation, the onset of wall
slip, yielding at the wall, and finally a steady-state plug flow that is well-described by the predictions of the Herschel-Bulkley model. I will then discuss experiments on the flow of Carbopol confined to square microchannels with sides ranging from 500 µm down to 50 µm. In the
larger channels, measured velocity profiles agree well with simulations based on the bulk rheology of the Carbopol and the Herschel-Bulkley model. In contrast, in microchannels smaller than 150 µm the velocity profiles could not be fitted by a model with a finite yield stress, but instead were described by a power-law model with zero yield stress. I will discuss the vanishing of the yield stress in terms of the effect of confinement on the microstructure of the Carbopol.
Host: Dimitris Vlassopoulos 1469
Time:
12:00 - 13:00
Location:
“Seminar Room 1”, FORTH’s bldg
Description:
IMBB SEMINAR
Michalis KOTSYFAKIS
Head of the Laboratory of Genomics and Proteomics of Disease Vectors,
Biology Center of the Czech Academy of Sciences,
Budweis, Czech Republic
Title: "The tick Ixodes ricinus as a model organism for discovering potent pharmacological activities"
Το Τμήμα Χημείας του Πανεπιστημίου Κρήτης διοργανώνει το Σάββατο 2 Δεκεμβρίου 2017, για πέμπτη συνεχόμενη χρονιά, Ημερίδα Χημείας στην οποία συμμετέχουν καθηγητές, μεταπτυχιακοί φοιτητές και υποψήφιοι διδάκτορες, αφιερωμένη στη μνήμη της αξέχαστης Δρ. Μαρίας Χατζημαρινάκη.
Η ημερίδα περιλαμβάνει ομιλίες σε σύγχρονα θέματα χημείας με μεγάλο ερευνητικό αλλά και πρακτικό ενδιαφέρον. Το πρόγραμμα της ημερίδας ολοκληρώνεται με την βράβευση ενός μεταπτυχιακού φοιτητή για εξαίρετη πορεία στις μεταπτυχιακές σπουδές. Το βραβείο συνοδεύεται και από χρηματικό έπαθλο, το οποίο ευγενώς προσφέρεται από την οικογένεια της Μαρίας Χατζημαρινάκη.
ΗΜΕΡΟΜΗΝΙΑ: Σάββατο, 2 Δεκεμβρίου 2017
ΩΡΑ: 9:30 πμ
ΑΙΘΟΥΣΑ: Αίθουσα σεμιναρίων Χημείας
Παρακαλούμε δείτε το σχετικό αρχείο:
http://news.uoc.gr/news/2017/29-11/ΠΡΟΓΡΑΜΜΑ.5ης.Ημερίδας.Χημείας.2017.pdf
In a first part I will focus on the destabilisation of dilute
oil-in-water emulsion-based liquid sheets expanding in air. A sheet
results from the collision of a single tear on a small solid target ; it
disintegrates through the nucleation and growth of holes that perforate
the sheet. We have developed an optical technique that allows the
determination of the time and space-resolved thickness of the sheet to
gain a, understanding of the physical mechanisms f the perforation
events This bursting based-liquid sheet destabilization is at the origin
of emulsion-based anti-drift formulations are developed for agricultural
spray. In a second part, I will investigate freely expanding sheets
formed by ultra soft spherical gel beads of elastic but also liquid
droplets with various surface tensions, and simple viscoelastic fluids
(Maxwell fluids), produced by impacting them on a silicon wafer covered
with a thin layer of liquid nitrogen that suppresses viscous dissipation
by an inverse Leidenfrost effect. The experiments reveal a universal
behaviour of the impact dynamics with impact velocity, for both solids
and liquids, and even viscoelastic fluids, that we have rationalized
BioMicroElectroMechanical Systems (Bio-MEMS) is an emerging technology
that aims to provide miniaturized, sophisticated, clinical devices and
research tools to the life science community. In this talk, I will
describe two such novel micro-technologies: (i) a new generation of
microfluidic devices that can manipulate whole micro-organisms (such as
the worm C. elegans) and image in vivo their neuronal responses at the
single neuron level. Functional imaging data from aged neurons from C.
elegans indicate, for the first time, that neural degradation is
affected by aging. These microfluidic devices can be further automated
for use in high-throughput anti-aging drug screening applications, and
(ii) a portable, Bio-MEMS platform for monitoring HIV-infected patients
in resource-limited settings. Such a platfrom can reach the end-user
wherever limited infrastructure is present and no access to a hospital
or clinic is possible. The proposed technology will not only make it
possible to monitor the efficacy of an individual’s therapy in the
developing world, but it will make more medicines available by
identifying patients who need a treatment from patients who do not need
it.
Host: Anna Mitraki 4095
Time:
13:00 - 14:00
Location:
“Seminar Room 1”, FORTH’s bldg
Description:
IMBB SEMINAR
Christoforos NIKOLAOU
Assistant Professor
Department of Biology
University of Crete
Title: "Chromatin Structure and Transcriptional Activity shaping Genomic Landscapes in Eukaryotes"
Investigating the role of dendrites in sparse representations in hippocampus using computational models
Supervisor: Assist.Prof., K.Sidiropoulou
Co-supervisor: Researcher A, P.Poirazi