print 
 wechseln zu deutsch 

Seminars - Summer term 2019

Seminar “Special problems in colloidal physics”

Location: HHU Düsseldorf, Seminarroom 25.32.O2.51
Program:
DateSpeakerTopicTime
Mon 08.04.2019   S. Reigh  Controlling crystallisation of colloidal particles via sound stimuli  14:30 s.t.
Thu 02.05.2019   R. Wittmann  Complex fluids in complex confinement  14:30 s.t.
Fri 03.05.2019   A. Sprenger  Self propelled particles in anisotropic environments  14:30 s.t.
Tue 07.05.2019   C. Hoell  Collective orientational ordering in microswimmer suspensions through hydrodynamic interactions  14:30 s.t.
Mon 20.05.2019   S. Jahanshahi  From microswimmers to microflyers IV—flashback: trapping of swimmers  14:30 s.t.
Tue 28.05.2019   S. Goh  A DFT study on the configurational bistability in ferrogels with an anisotropic model  14:30 s.t.
Important notice - different location - Seminarroom 25.32 O3.51
Mon 08.07.2019   A. Ider  Hydrodynamics of a circle microswimmer in a nematic liquid crystal  14:30 s.t.
Prof. Dr. H. Löwen

top

Seminar “Special problems in computer simulation of soft matter”

Location: HHU Düsseldorf, Seminarroom 25.32.O2.51
Program:
DateSpeakerTopicTime
Mon 08.04.2019   S. Reigh  Controlling crystallisation of colloidal particles via sound stimuli  14:30 s.t.
Mon 15.04.2019   M. Golkia  Mechanical properties of deformed bulk metallic glasses  14:30 s.t.
Mon 20.05.2019   S. Jahanshahi  From microswimmers to microflyers IV—flashback: trapping of swimmers  14:30 s.t.
Tue 28.05.2019   S. Goh  A DFT study on the configurational bistability in ferrogels with an anisotropic model  14:30 s.t.
Important notice - different location - Seminarroom 25.32 O3.51
Mon 08.07.2019   A. Ider  Hydrodynamics of a circle microswimmer in a nematic liquid crystal  14:30 s.t.
Prof. Dr. J. Horbach

top

Seminar “Soft Matter”

Location: HHU Düsseldorf, Seminarroom 25.32.O2.51
Program:
DateSpeakerAffiliationTime
Thu 27.06.2019   Anand Yethiraj  Memorial University of Newfoundland, Canada  14:30 s.t.
NMR studies of crowding
Thu 11.04.2019   Ties van der Laar  Wageningen University, The Netherlands  14:30 s.t.
Ties van der Laar: „Sticky, squishy and stuck. A soft matter approach to membrane failure”
Wageningen University, The Netherlands - Seminar@HHUD: 11.4.19 14:30 s.t., Seminarroom 25.32 O2.51

In this talk I will highlight various ways we have used soft matter science to solve problems in membrane technology. We have developed microfluidic tools to study clogging, used colloidal particles to study cake formation and developed sensors to measure very small forces that might play a role in these processes. My focus will be on the colloidal scale and I will highlight two specific examples, one related to clogging and the other related to the colloidal glass transition.

Sticky, squishy and stuck. A soft matter approach to membrane failure
Wed 03.04.2019   Lei Zhu  Case Western Reserve University, Cleveland, Ohio, United States of America  13:00 s.t.
Lei Zhu: „High Energy Density and Low Loss Dielectric Polymers for Electrical Applications”
Case Western Reserve University, Cleveland, Ohio, United States of America - Seminar@HHUD: 3.4.19 13:00 s.t., Seminarroom 25.32 O2.51

High dielectric constant polymers find numerous advanced electrical and power applications such as pulsed power, power conditioning, gate dielectrics for field-effect transistors, electrocaloric cooling, and electromechanical actuation. Unfortunately, it is generally observed that polymers do not have high dielectric constants (only 2-5) and high polarization tends to cause a significantly dielectric loss. Therefore, it is highly desirable that the fundamental science of all types of polarization and loss mechanisms be thoroughly understood for dielectric polymers. In this presentation, we intend to explore advantages and disadvantages for different types of polarization. Among a number of approaches, orientational polarization is promising for high dielectric constant and low loss polymer dielectrics, if the dipolar relaxation peak can be pushed to towards the gigahertz range. In particular, dipolar glass, paraelectric, and relaxor ferroelectric polymers will be discussed for the orientational polarization approach.

High Energy Density and Low Loss Dielectric Polymers for Electrical Applications
Fri 22.02.2019   Damien Vandembroucq  Paris, France  11:30 s.t.
SPP1594 SpringSchoolTalk: Fracture and plasticity of disordered materials II
Fri 22.02.2019   Yannick Champion  Grenoble, France  9:30 s.t.
SPP1594 SpringSchoolTalk: Statistical and entropic description of metallic glass
Thu 21.02.2019   Jörg Baschnagel  Université de Strasbourg, France  11:15 s.t.
SPP1594 SpringSchoolTalk: Shear stress and shear-stress fluctuations in simulated amorphous systems II
Thu 21.02.2019   Yannick Champion  Grenoble, France  9:30 s.t.
SPP1594 SpringSchoolTalk: Thermal activation of shear band formation in metallic glass
Wed 20.02.2019   Frans Spaepen  Harvard University, USA  9:30 s.t.
SPP1594 SpringSchoolTalk: The Continuous Random Network - a Review
Tue 19.02.2019   Damien Vandembroucq  Paris, France  16:30 s.t.
SPP1594 SpringSchoolTalk: Fracture and plasticity of disordered materials I
Tue 19.02.2019   Frans Spaepen  Harvard University, USA  15:00 s.t.
SPP1594 SpringSchoolTalk: An Overview of the Mechanical Behavior of Metallic Glasses
Tue 19.02.2019   Jörg Baschnagel  Université de Strasbourg, France  13:15 s.t.
SPP1594 SpringSchoolTalk: Shear stress and shear-stress fluctuations in simulated amorphous systems I
Wed 13.02.2019   Carmen Lucía Moraila Martínez  University of Sinaloa, Culiacán, Mexico  14:30 s.t.
Carmen Lucía Moraila Martínez: „Morphological study of drying complex fluids: a low resources technique for dengue virus detection”
University of Sinaloa, Culiacán, Mexico - Seminar@HHUD: 13.2.2019 14:30 s.t., Seminarroom 25.32 O2.51

Drying of colloidal suspensions appears in many applications such as coatings (paints, ink printing, paving), colloidal assembly/templating, discrimination of particles with different size, even medical diagnostics. Complex liquids, suspensions of solid particles, polymeric dispersions, emulsions and simple liquids behave in different way at interfacial regions.

The formation of stains at the periphery of drying drops of any colloidal dispersion is known as the "coffee stain" effect or "coffee ring" effect. The mechanism for particle deposition by drop drying and the study of the morphology of the deposits left, have been widely studied. The first study proposing a physical model was published by Deegan et al. [1] They demonstrated that there were two conditions necessaries for ring-like deposits apparition: contact line pinning and evaporation from the edge of the drop.

Controlling the distribution of solute during drying is vital in many industrial and scientific processes. The "coffee ring" effect is used for an innovative approach for medical diagnostics. It is based on the comparison of the patterns of dried drops of biological liquids of people with different diseases with regard to people in healthy conditions.

In the field of medicine, one of the great challenges for health in the world is the diagnosis of diseases in an economic way, particularly in countries with low resources. Therefore, the development of techniques that require a minimum use of energy and resources become a necessity.

Recently, it has been found that different diseases (such as HIV, tuberculosis or malaria) can be diagnosed using techniques of biological fluids evaporation. During the drying of a biological fluid an evaporative flow occurs that carries the particles (bacteria, cells, etc.) to the interface and, in the wedge formed by the triple line, a particle segregation by size is presented. This segregation occurs only under certain conditions in which the wetting properties of the surface and particles, electrical charge, particle concentration, play a very important role. In the present work, we propose an indirect, rapid and low resources technique for Dengue virus detection by the drying of a blood micro-drop and the subsequent study of drying morphology.

Reference

  1. Deegan et al., Nature 389, 827–829 (1997)
Morphological study of drying complex fluids: a low resources technique for dengue virus detection
Tue 12.02.2019   Lorenzo Caprini  Gran Sasso Science Institute, L´ Aquila, Italy  14:30 s.t.
Activity-induced delocalization and freezing for self-propelled particles
Prof. Dr. Egelhaaf, Prof. Dr. Horbach, Prof. Dr. Löwen

top

Colloquia

Location: HHU Düsseldorf, Lecture Hall 5J (Building 25.31 Level 00)
Program:
DateSpeakerAffiliationTime
Thu 27.06.2019   Prof. Dr. Achim Rosch  Universität zu Köln  16:30 s.t.
t.b.a.
Thu 13.06.2019   Prof. Dr. Gérard Mourou  École Polytechnique, Palaiseau, France  17:00 s.t.
Prof. Dr. Gérard Mourou: „Verleihung der Ehrendoktorwürde: Passion extreme light”
École Polytechnique, Palaiseau, France - Seminar@HHUD: 13.6.19 17:00 s.t., Lecture hall 3A 23.01 O0.3A

Extreme-light laser is a universal source providing a vast range of high energy radiations and particles along with the highest field, highest pressure, temperature and acceleration. It offers the possibility to shed light on some of the remaining unanswered questions in fundamental physics like the genesis of cosmic rays with energies in excess of 1020 eV or the loss of information in black-holes. Using wake-field acceleration some of these fundamental questions could be studied in the laboratory. In addition extreme-light makes possible the study of the structure of vacuum and particle production in "empty" space which is one of the field’s ultimate goal, reaching into the fundamental QED and possibly QCD regimes.

Looking beyond today’s intensity horizon, we will introduce a new concept that could make possible the generation of attosecond-zeptosecond high energy coherent pulse, de facto in x-ray domain, opening at the Schwinger level, the zettawatt, and PeV regime; the next chapter of laser-matter interaction.

Verleihung der Ehrendoktorwürde: Passion extreme light
Important notice - different location - Lecture hall 3A 23.01 O0.3A
Thu 06.06.2019   WE Physik  Heinrich-Heine-Universität Düsseldorf  16:30 s.t.
Gedenkkolloquium für Prof. Dr. Andreas Otto
Thu 23.05.2019   Prof. Dr. Thomas Udem  Max-Planck-Institut für Quantenoptik, Garching  16:30 s.t.
Prof. Dr. Thomas Udem: „Challenging QED with atomic Hydrogen”
Max-Planck-Institut für Quantenoptik, Garching - Seminar@HHUD: 23.5.19 16:30 s.t., Lecture hall 25.31 O0.5J

Precise determination of transition frequencies of simple atomic systems are required for a number of fundamental applications such as tests of quantum electrodynamics (QED), the determination of fundamental constants and nuclear charge radii. The sharpest transition in atomic hydrogen occurs between the metastable 2S state and the 1S ground state with a natural line width of only 1.3 Hz. Its transition frequency has been measured with almost 15 digits accuracy using an optical frequency comb and a cesium atomic clock as a reference [1]. A measurement of the Lamb shift in muonic hydrogen is in significant contradiction to the hydrogen data if QED calculations are assumed to be correct [2]. In order to shed light on this discrepancy the transition frequency of one of the broader lines in atomic hydrogen has to be measured with very good accuracy [3].

References

  1. C. G. Parthey et al., Phys. Rev. Lett. 107, 203001 (2011).
  2. A. Antognini et al., Science 339, 417, (2013).
  3. A. Beyer et al., Science 358, 79 (2017).
Challenging QED with atomic Hydrogen
Thu 16.05.2019   Prof. Dr. Piet Brouwer  Freie Universität Berlin  16:30 s.t.
Prof. Dr. Piet Brouwer: „Higher-order topological insulators and superconductors”
Freie Universität Berlin - Seminar@HHUD: 16.5.19 16:30 s.t., Lecture hall 25.31 O0.5J

Topological insulators combine an insulating bulk with gapless states at their boundaries. This talk introduces "higher-order topological insulators", which are crystalline insulators with a gapped bulk and gapped crystalline boundaries, but topologically protected gapless states at the intersection of two or more boundaries. I´ll show that reflection symmetry and other spatial symmetries can be employed to systematically generate examples of higher-order topological insulators and superconductors, although the topologically protected states at corners or at crystal edges continue to exist if the crystalline symmetry is broken.

Higher-order topological insulators and superconductors
Thu 09.05.2019   Prof. Dr. Stephan Herminghaus  Max-Planck-Institut für Dynamik und Selbstorganisation Göttingen  16:30 s.t.
Prof. Dr. Stephan Herminghaus: „Active Matter and Sustainability: from Plankton to Traffic Flow”
Max-Planck-Institut für Dynamik und Selbstorganisation Göttingen - Seminar@HHUD: 9.5.19 16:30 s.t., Lecture hall 25.31 O0.5J

The most important question of our time is whether, and how, we will be able to run our planet sustainably. Answering this question requires a deep understanding of the earth system, a vast non-equilibrium system which abounds with different active-matter subsystems. Two of them are within the focus of the talk: the plankton, which represents the bottleneck of solar energy entering the marine biosphere, and traffic flow, which is among the strongest sources of greenhouse emissions. Despite the complexity and disparity of the two systems, basic statistical physics methodology may pave the way towards understanding their overall behaviour.

Active Matter and Sustainability: from Plankton to Traffic Flow
Thu 11.04.2019   Prof. Dr. Roberto Piazza  Politecnico di Milano, Italy  16:30 s.t.
Prof. Dr. Roberto Piazza: „The magic of soft matter”
Politecnico di Milano, Italy - Seminar@HHUD: 11.04.2019 16:30 s.t., Lecture hall 25.31 O0.5J

What could ever share milk and fine dust, ice cream and shaving foam, rice and sand, tires and ricotta cheese, crude oil and suntan cream, cells and soap bubbles? Nothing, apparently. Yet, the opposite is true. In the air we breathe like in the food we eat, in the clothes we wear like in the detergents used to wash them, in paints in color screens are intimately hidden some little characters, invisible to our eyes but great in creativity and ingenuity.

Besides being at the roots of cutting-edge industrial processes of today and tomorrow, these busy sprites, which are the basic constituents of what scientists call "soft matter", prompt us to explore the deep secrets of matter and to follow step by step self-organizing phenomena ranging from the formation of soap bubbles to the making of biological machines. For life itself is nothing but the "happy hour" of this fantastic Middle-earth between molecules and man.

In this talk, I shall try and guide you along a brief introductory journey to the world of nanoparticles, polymers, surfactants, and biological fluids, with the main aim of fostering a reflection on our intimate bounds with many simple things that surround us.

The magic of soft matter
Thu 31.01.2019   Prof. Dr. Robert Evans  HH Wills Physics Laboratory, University of Bristol, United Kingdom  16:30 s.t.
Prof. Dr. Robert Evans: „Understanding the structure of simple and complex liquids: what we know that Mr. Kirkwood did not know.”
HH Wills Physics Laboratory, University of Bristol, United Kingdom - Seminar@HHUD: 31.01.2019 16:30 s.t., Lecture hall 25.31 O0.5J

The great L.D. Landau argued that there is no theory of liquids; he did not write about liquids in his famous books. J.G. Kirkwood took a different track. This talk will address basic questions on what distinguishes a liquid from a gas or from a crystalline solid and how the form of the pair correlation function g(r) reflects the nature of the ordering.

How g(r) decays at large r defines crossover lines in the phase diagram. These lines are not phase boundaries but point to i) how repulsive and attractive interparticle forces compete to determine structure and ii) how in experiments and simulations on binary colloidal mixtures with different sizes, the presence of two different length scales leads to a sharp structural crossover line: the three gij(r) decay with a common (short) wavelength on one side and with long wavelength on the other.

For certain one-component models with pair potentials exhibiting two (suitably chosen) competitive length scales, we find a structural crossover line that points, at high packing, to where in the phase diagram quasi-crystals might form.

We reflect upon what is known about the structure of liquids.

Understanding the structure of simple and complex liquids: what we know that Mr. Kirkwood did not know.
Thu 10.01.2019   Prof. Dr. Rodrigo Pereira  Federal University of Rio Grande do Norte/ Natal, Brazil  16:30 s.t.
Prof. Dr. Rodrigo Pereira: „From quantum spin chains to chiral spin liquids”
Federal University of Rio Grande do Norte/ Natal, Brazil - Seminar@HHUD: 10.01.2019 16:30 s.t., Lecture hall 25.31 O0.5J

Chiral spin liquids are highly entangled phases of matter in which interacting spins break time reversal and reflection symmetries, but do not develop conventional magnetic order even at zero temperature. They are expected to exhibit exotic properties following from a spectrum of deconfined fractional excitations, and the first signatures of such properties may have just been observed in recent experiments. In this talk I will explain our current theoretical understanding of chiral spin liquids in terms of effective field theories ranging from strongly coupled gauge theories to coupled-chain constructions based on arrays or junctions of quantum spin chains.

From quantum spin chains to chiral spin liquids
Thu 20.12.2018   Prof. Dr. Stefan U. Egelhaaf  Heinrich-Heine-Universität Düsseldorf  16:30 s.t.
Prof. Dr. Stefan U. Egelhaaf: „Manipulating particles with light – The Nobel Prize in Physics 2018”
Heinrich-Heine-Universität Düsseldorf - Seminar@HHUD: 20.12.2018 16:30 s.t., Lecture hall 25.31 O0.5J

Arthur Ashkin was awarded (a share of) the Nobel Prize in Physics 2018 'for the optical tweezers and their application to biological systems'. I will explain why optical means, so-called optical tweezers, can be used to manipulate small objects, in the range from nanometers to micrometers. This is particularly appealing because the objects can be manipulated without directly interfering with the sample. Optical tweezers are nowadays applied to a broad range of objects, including colloids, biomolecules and living cells. The diversity of systems and questions which can be addressed using optical tweezers will be illustrated with examples. This includes experiments performed in our lab, which are based on optical tweezers but also take this concept a step further.

Manipulating particles with light – The Nobel Prize in Physics 2018
Thu 22.11.2018   Dr. Götz Lehmann  Heinrich-Heine-Universität Düsseldorf  16:30 s.t.
Dr. Götz Lehmann: „Eigenschaften und Anwendungen akustischer Metamaterialien”
Heinrich-Heine-Universität Düsseldorf - Seminar@HHUD: 22.11.2018 16:30 s.t., Lecture hall 25.31 O0.5J

Akustische Metamaterialien bestehen aus „Meta-Atomen”, elementaren Bausteinen, die größer sind als Atome, jedoch kleiner als die Wellenlänge von Schallwellen. Es sind die Struktur dieser Bausteine und ihre geometrische Anordnung, die über die Ausbreitung von Schallwellen in Metamaterialien entscheiden. Auf diese Weise lassen sich akustische Eigenschaften realisieren, die mit gewöhnlichen Materialien unmöglich sind.

Die akustischen Eigenschaften eines Materials sind in der Regel bestimmt durch die Massendichte und den Kompressionsmodul. Es erscheint uns völlig selbstverständlich, dass diese Parameter keine negativen Werte annehmen können. In Metamaterialien besitzt nun einer der Parameter, oder sogar beide, einen Wert kleiner Null. In meinem Vortrag werde ich vorstellen, wie sich effektiv negative Werte für diese beiden Parameter realisieren lassen und welche Konsequenzen dies für die Ausbreitung von Schall hat.

Im zweiten Teil des Vortrages werde ich über mögliche Anwendungen von akustischen Metamaterialien sprechen. Neben extrem dünnen Schallisolierungen lassen sich akustische Superlinsen und Tarnkappen konstruieren. Superlinsen erlauben das Fokussieren von Schallwellen jenseits der Beugungslimits, was gerade im Bereich der Ultraschalldiagnostik Interesse weckt. Mit Hilfe von akustischen Tarnkappen lässt sich die Gegenwart von Objekten vor dem Schallfeld verstecken.

Eigenschaften und Anwendungen akustischer Metamaterialien
WE Physik, Heinrich-Heine-Universität Düsseldorf

top

Seminar about Bachelor, Master and other Theses from the Institut for Theoretical Physics II

top

Link: Physics Colloquium
tp2admin <at> thphy.uni-duesseldorf.de · Last modified: Wed, May 22 2019 14:52:23 · ©2019-ThPhyII