Seminaria Zakładu Biosystemów i Miękkiej Materii

Pawińskiego 5b

kolor czcionki + kolor tła = plan do 7 dni.

2017-12-20
 plan 
12:30, Sala: S3 im. W. Fiszdona, piętro III
Valentina Grippo
Warsaw University

Lipidic cubic phase for hosting enzymes and improving their catalytic activity

2017-12-06
 plan 
12:30, Sala: S3 im. W. Fiszdona, piętro III
Dr Robert Owczarek
University of New Mexico

A story on knotted links between knots, links, the associated invariants, and Chebyshev/Fibonacci/Lucas invariants

Topology has become very important in studying condensed matter systems recently to the extent that it is one of the most popular games in town. My interest in topology grew up during studies of vortices in superfluid helium and their role in the phase transition between normal and superfluid helium. Knotted and linked vortex structures proved to contribute to the transition. Such structures are mathematically described by various knot and link invariants, which I will discuss briefly in seminar. Examples of invariants include Alexander polynomial, Fox tricoloring, Jones polynomial, Khovanov homology. An intriguing and puzzling fact in studies of knot invariants is appearance of Chebyshev polynomials in various roles. I will try to make a small step forward in understanding of this role, and as a byproduct I will propose a generalization of Chebyshev polynomials so that they include the standard Chebyshev polynomials, Lucas polynomials, and Fibonacci polynomials (and yes, the latter are related to Fibonacci series) as special cases. This generalization opens a way to a generalization of the Jones polynomial in the sense I will discuss in the seminar, and perhaps more, though I am not going to go that far in this seminar.

2017-10-25
12:30, Sala: S3 im. W. Fiszdona, piętro III
dr Filippo Pierini
IPPT PAN

Electrospinning of conjugated polymer nanofibers: research challenges and applications

Conjugated polymers are a class of organic macromolecules with large π-conjugated polymer chains due to a backbone chain of alternating double- and single-bonds. The highly electron-delocalized structures generated by the overlapping of p-orbitals create systems with fascinating electronic and optical properties. Conjugated polymer nanomaterials have been shown to be promising for advanced organic electronic, photovoltaic and biomedical applications.

Electrospinning is the most efficient technique for elongating and aligning polymer chains to form nanofibers with a well-defined structure. This technique is particularly interesting in order to fabricate continuous polymer 1D nanostructures with controllable composition, structure and properties. Chemical and physical properties of conjugated polymer nanofibers could be modulated by controlling their hierarchical structure by way of electrospinning [1-3]. The major challenge in the development of these materials has been obtaining a balance between polymer properties and spinnability.

During this seminar, a brief overview of conjugated polymer material properties will be presented. In the second part, principles of the electrospinning of conjugated polymer will be discussed. Finally, recent results on the development of electrospun nanofiber-based devices and their applications will be demonstrated [4].

REFERENCES

[1] F. Pierini et al., “Electrospun poly(3-hexylthiophene)/poly(ethylene oxide)/graphene oxide composite nanofibers: effects of graphene oxide reduction", Polymers for Advanced Technologies, 27 (2016) 1465–1475.

[2] F. Pierini et al., “Comparison between inorganic geomimetic chrysotile and multiwalled carbon nanotubes for the preparation of one-dimensional conducting polymer nanocomposites”, Fibers and Polymers, 16, (2015) 426-433.

[3] F. Pierini et al., "Electrospun polyaniline-based composite nanofibers: tuning the electrical conductivity by tailoring the structure of thiol-protected metal nanoparticles", Journal of Nanomaterials, 6142140 (2017) 10.

[4] F. Pierini et al., “Single-material organic solar cells based on electrospun fullerene-grafted polythiophene nanofibers” Macromolecules, 50, 13 (2017) 4972-4981.

2017-10-18 12:30, Sala: S3 im. W. Fiszdona, piętro III
dr inż. Izabela Piechocka
IPPT PAN

The effect of shear flow on fibrin clot structure and fibrin-platelets interactions

Fibrin and platelets are the two main components involved in blood clot formation, preventing bleeding and promoting wound repair. In vivo, the formation of blood clots takes place in the presence of flowing blood that exerts a continuous shear force on the whole structure, influencing its mechanical properties such as extensibility and resistance. The exact role of the shear flow in bulk organization of fibrin networks and in fibrin-platelet interactions at the nanometer scale still remains, however, unexplored.

Here, by bring together parallel-plate flow chamber (PPFC) together with confocal microscope, we plan to follow in situ changes in fibrin network structure at the bulk level and the level of individual fibrin filaments. By using combination of PPFC together with super-resolution microscopy techniques such as stimulated emission depletion microscopy (STED) or stochastic optical reconstruction microscopy (STORM), we plan to uncover the role of shear flow in spatial organization of fibrin-platelet adhesion receptors.

Such fibrin-platelets model system will closely mimics the in vivo situation of blood clots, providing a crucial insight into the role of shear flow in the extracellular matrix (ECM)-cell interactions which is important in light of the biological function of blood clots.

2017-10-11 12:30, Sala: S3 im. W. Fiszdona, piętro III
dr hab. Piotr Korczyk
IPPT PAN

Self-counting droplets and other microfluidic curiosities

Integrated logic elements with embedded digital operations into the structure of the device has been successfully implemented in electronics, becoming one of the pillars of the information revolution.

About one decade ago Manu Prakash demonstrated, that single fundamental logic operations can be implemented in the two-phase microfluidic flows due to the utilization of nonlinearity introduced by surface interactions. Those findings raised a hope that further integration of these base units would enable construction of architectures inducing programmed cascades of digital operations on droplets or bubbles. That approach would pave the way for autonomous microfluidic systems with all analytical procedures hard-wired into the structure of the device. However, until now there is a lack of examples of realization of that promising idea.

Herein we show the new approach to the construction of microfluidic geometries, which perform the logic operations on sequences of droplets. We explain the working principles and, what is most important, we demonstrate that those single units can be successfully arranged into larger systems performing sequences of operations. Finally, we demonstrate the examples of encoding of the digital procedures of counting of droplets in both binary and decimal systems. In our microfluidic architectures, some of the droplets flowing into the counter play a role of indicators and their positions correspond directly to the current count of all flowing droplets. Such microfluidic counters can be arranged in series to count a custom number of droplets. We show and test a few construction of the counters, which can count reliably up to 1000 droplets.

Presented devices show the fascinating aspect of microfluidics, where continuous flows of liquids crossed in microfluidic junction spontaneously transform into the discrete droplets and then these droplets perform digital computations.

2017-09-29 12:30, Sala: S3 im. W. Fiszdona, piętro III
Prof. Jochen Rink
Max Planck Institute of Molecular Cell Biology and Genetics
Dresden, Germany

Pattern establishment and scaling in planarians

Planarian flatworms are astonishing creatures. They have the ability to regenerate complete and perfectly proportioned individuals from tiny tissue fragments. They grow when fed and literally shrink when starving, continuously varying their body size between less than one mm and several cm in length. Abundant pluripotent adult stem cells serve as sole source of new cells and their continuous divisions continuously renew all organismal cell types. Such unique biology epitomizes a fascinating challenge: How to regenerate, maintain and scale form and function of a triploblastic body plan? My lab approaches this problem from multiple angles, including the patterning systems specifying the body plan, the multi-level control of organismal growth dynamics and via the comparative analysis of our large live collection of planarian species. We recently found that the planarian A/P axis is patterned by a self-organizing Wnt gradient deployed from the tail tip, which exists in mutual antagonism with a similar patterning system deployed from the head. Current work addresses the transformation of the signaling gradients into cell fate choices and the evolutionary changes in the signaling network that ultimately explain why some planarians regenerate, while others do not.

2017-09-26 10:30, Sala: S3 im. W. Fiszdona, piętro III
Chris Trombley
IPPT PAN

Stability And Earnshaw’s Theorem In A Viscous Fluid

Seminarium w ramach przeglądu wyników doktorantów uzyskanych w 2016/17.
2017-09-13 12:30, Sala: S3 im. W. Fiszdona, piętro III
Paramita Chatterjee
IPPT PAN

Mathematical analysis of a limb growth model

Seminarium w ramach przeglądu wyników doktorantów uzyskanych w 2016/17.

Vertebrate limb development is an important example of organogenesis. In [1], Glimm and coauthors proposed a new model related to bone formation based upon the results of an experimental paper [2]. It differs significantly from any previously discussed model of growing limb. In [2], a crucial role of new morphogens regulating the cells aggregation and bone formation during avian limb growth has been reported. The main mathematical feature of the Glimm’s model is that it is described by a system of equations which are neither parabolic nor hyperbolic. Here we propose a possible approach of the model analysis.

1. T. Glimm, R. Bhat, S.A. Newman, Modeling the morphodynamic galectin patterning network of the developing avian limb skeleton,J.Theor. Biol.,346(2014), pp. 86108.
2. Bhat, R., Lerea, K.M., Peng, H., Kaltner, H., Gabius, H.J., Newman, S.A., A regulatory network of two galectins mediates the earliest steps of avian limb skeletal morphogenesis, BMC developmental biology, 11(1), (2011), 1.

2017-06-28 12:30, Sala: S3 im. W. Fiszdona, piętro III
prof. Jerzy Bławzdziewicz
Department of Mechanical Engineering,
Texas Tech University, Lubbock, TX, USA

Geometry and mechanics in soft biological matter: an analysis of nematode locomotion and fruit fly morphogenesis

The interplay between geometry and mechanical forces plays a subtle but very important role in diverse biological systems. In our first example we will focus on locomotion of the nematode C. elegans in 2D and 3D environments. We will investigate optimization and neuromuscular control of nematode gait patterns in different media; we also discuss the geometry and biomechanics of its turning maneuvers. The second example will center on the formation of embryonic architecture during fruit fly morphogenesis; in our analysis we argue that mechanical feedback is crucial for robustness of morphogenetic movements.

2017-06-21 12:30, Sala: S3 im. W. Fiszdona, piętro III
mgr Karol Nienałtowski
IPPT PAN

Quantitative methods for analysing cellular signalling

Seminarium w ramach przeglądu wyników doktorantów uzyskanych w 2016/17.

The complexity of biochemical signalling induce usage a combination of tailored experimental measurements with quantitative approaches for better understanding signalling mechanisms. My research is focused on: (1) development software for quantification of high-througput single cell-measurements and (2) mathematical methodology for analysing signalling mechanisms. We proposed non-parametric modelling method for reconstructing trajectory of cellular response to the stimuli from single-cell snapshot data. Moreover, we work on developing stochastic models of interferones signalling in normal cell lines of human lung epithelium as well as in human non-small cell lung cancer cell lines that combine intrinsic and extrinsic sources of cellular variability. During the seminar I will present previous results of my PhD project and plan of work for the next year.

2017-06-14 12:30, Sala: S3 im. W. Fiszdona, piętro III
Professor Krzysztof Kuczera
Departments of Chemistry and Molecular Biosciences
The University of Kansas, Lawrence, USA

Modeling peptide solvation by denaturing and protective co-solvents

2017-04-26 12:00, Sala: S3 im. W. Fiszdona, piętro III
mgr Marek Bukowicki
IPPT PAN

Dynamics of settling pairs of elastic particles at low Reynolds number regime

I will discuss dynamics of symmetric pairs of particles, settling in viscous fluid. Results for two regimes will be presented: the system of rigid particles, where periodic solutions are observed, and the system of elastic particles.

2017-03-20 14:30, Sala: S3 im. W. Fiszdona, piętro III
dr inż. Marta Grodzik
Zakład Nanobiotechnologii, SGGW

Antyglejakowa terapia grafenem - nadzieje i obawy

2017-01-11 12:30, Sala: S3 im. W. Fiszdona, piętro III
dr Gustavo Abade
Institute of Geophysics, University of Warsaw

Active microrheology in a colloidal glass of hard spheres

The talk will address the dynamics of a probe particle driven by a constant force through a colloidal glass of hard spheres. This nonequilibrium and anisotropic problem is investigated using a new implementation of the mode-coupling approximation with multiple relaxation channels and Langevin dynamics simulations. An important feature of the system is the critical force, above which the probe delocalizes. Friction coefficients of delocalized probes decrease with force, indicating force-thinning behavior. Probe van Hove functions predicted by the theory show exponential tails reminiscent of an intermittent dynamics of the probe. This scenario is microscopically supported by simulations.

2016-12-21 12:30, Sala: S3 im. W. Fiszdona, piętro III
dr Karol Makuch
Instytut Chemii Fizycznej PAN

Speed of flow of non-wetting droplets in capillaries of circular cross-section

We measure mobility of long droplets in circular microfluidic channels. Using oil as a continuous phase and aqueous solutions of glycerol with die as droplet phase, we determine mobility for the range of values of the capillary number Ca∈(〖10〗^(-5),〖10〗^(-2) ) and ratio of viscosities of the droplet and continuous phase λ∈(0.25,10). To explain the results of our experiments, we also introduce approximate method of calculation of the speed of viscous droplets. This theoretical approach is based on lubrication approximation.

2016-12-14 12:30, Sala: S3 im. W. Fiszdona, piętro III
dr Paweł Żuk
IPPT PAN

On the viscosity of rigid models of molecules

The viscosity of complex fluids very strongly depends on their composition. For many medical and technological applications it is important to know how does the macroscopic viscosity change with the shape of suspended molecules. We will show ho to calculate the viscosity of macromolecules modeled as bead modes and treat some artificial problems that can be found in the literature like "the center of viscosity".

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