Department of Physics

Physics Friday Colloquia

– Autumn 2015

Department of Physics organizes a series of colloquia. Friday's colloquium is open to everyone. It will be served tea/coffee and biscuits from 14:00. Talk starts at 14:15.

Time: Friday at 14:15 - 15:00

Location: Realfagbygget R10


Friday colloquia, Autumn 2015

September 8

Nicolas H. Voelcker, Mawson Institute, University of South Australia
«Nanostructured Silicon in Nanomedicine»

September 8

Nicolas H. Voelcker, Mawson Institute, University of South Australia
«Nanostructured Silicon in Nanomedicine»
 
Lecture on Tuesday 08.09.2015 at 14.15-15.00 in room 140

Abstract

Nanostructured Silicon in Nanomedicine

This talk will explore the application of nanostructured silicon including porous silicon and silicon nanowires in localised drug delivery, optical and electrochemical biosensors and tissue engineering. These silicon-based materials have high surface area of up to several hundreds of square meters per gram, facilitating loading of considerable amounts of bioactives.

Second, pore size can be tailored over a wide range, spanning from the nano- to the microscale. Being able to 'dial in' a certain pore size allows for facile optimisation of topographical cues for attachment, guidance, proliferation and differentiation of target cells. At the same time, the rate of diffusive release of drugs can be tuned by adjusting the pore size.

Third, the materials are biocompatible and biodegradable, undergoing oxidative hydrolysis in aqueous medium at a rate that is easily tunable by means of the surface chemistry from hours to months [1]. A diverse range of surface chemistries is available for this material, some of which are amenable to surface patterning, formation of surface-bound gradients and formation of silicon-polymer hybrid materials [2,3].

Finally, thin films, membranes and particles of porous silicon display interferometric reflectance and photonic effects, which are responsive to binding of target biomolecules [4].

This talk will first introduce nanostructured silicon material properties and fabrication and characterisation aspects, including describing strategies for nano- and microscale patterning and gradient formation [5]. This will be followed by an overview of the recent biomaterial applications including examples of the use as a biodegradable biomaterial for ocular tissue engineering [6]. Drug delivery applications for targeted cancer therapy and the therapy of ocular diseases will be highlighted [7,8]. Finally, the use of nanostructured silicon in chronic wound diagnostics and theranostics will be discussed [9].

  1. S.P. Low et al. Biomaterials, 27 (2006), 4538-4546.
  2. Y.L. Khung et al., Controlled drug delivery from composites of nanostructured porous silicon and poly(Llactide),
  3. Nanomedicine, 7 (2012), 995-1016.
  4. A. Jane et al. Trends in Biotechnology, 27 (2009), 230-239.
  5. M. Sweetman et al. Advanced Functional Materials, 22 (2012), 1158-1166.
  6. S. Kashanian, et al. Acta Biomaterialia, 6 (2010) 3566–3572.
  7. E. Secret et al. , K. Advanced Healthcare Materials, 2 (2013), 718-727.
  8. H. Alhmoud et al., Advanced Functional Materials, accepted 21.11.2014 10.1002/adfm.201403414.
  9. F.S.H. Krismastuti et al. Advanced Functional Materials, 24 (2014), 3639-3650.

Abstract: Nanostructured Silicon in Nanomedicine [pdf]


Professor Nicolas H. Voelcker

After completing his BSc at the University of Saarland (1993) and his MSc at the RWTH Aachen (1995) in Germany, Nico completed a PhD thesis (1999) in polymer surface chemistry at the DWI Leibniz Institute for Interactive Materials under Professor Hartwig Höcker. He received postdoctoral fellowships to work in the area of bioorganic chemistry under Professor Reza Ghadiri at the Scripps Research Institute in La Jolla, California. In 2001 he became a Lecturer at Flinders University in Australia, an Associate Professor in 2006 and a full Professor in 2008. From 2008-2011, he was the Associate Head of the Faculty of Science and Engineering at Flinders University. Since 2012, he is a Professor in Chemistry and Materials Science at the Mawson Institute of the University of South Australia. Since 2013, he is Deputy Director of the Mawson Institute. Since 2014, he is also Node Leader in the Australian Research Council Centre of Excellence in Convergent Bio-Nano Science and Technology.

Wed, 16 Sep 2015 13:19:48 +0200

September 18

Malin Torsæter, SINTEF Petroleum Research
«Exploring "inner space" by drilling deep wells»

September 18

Malin Torsæter, SINTEF Petroleum Research
«Exploring "inner space" by drilling deep wells»

Abstract

Exploring "inner space" by drilling deep wells

Wed, 16 Sep 2015 15:41:48 +0200

October 9

Yves Couder, Laboratoire Matière et Systèmes Complexes, Université Paris Diderot
«Self-organisation in a memory-endowed wave-particle systems»

October 9

Yves Couder, Laboratoire Matière et Systèmes Complexes, Université Paris Diderot
«Self-organisation in a memory-endowed wave-particle systems»

Abstract

Self-organisation in a memory-endowed wave-particle systems

Self-organisation is a term generally used to describe the dynamics of many interacting objects. In this talk I will describe a case in which a single structure undergoes self-organization by its interaction with its own past.

The object we are concerned was nicknamed “a walker”. It is formed of a droplet bouncing on a vertically vibrated liquid interface that is dynamically coupled to the surface wave it excites. This system is characterized by a specific information interplay. The particle generates waves and the waves determine where the particle goes. It is more than a classical echo-location because the waves have specific assets: they are standing waves temporally sustained. As a result their interference structure contains a memory of the drop recent trajectory.

I will specifically discuss recent experiments in which a walker, confined in a potential well, has an orbiting motion. In this situation the possible orbits exhibit both a form of quantization (1) and probabilistic behaviours (2).

  1. S. Perrard, M. Labousse, M. Miskin, E. Fort, & Y. Couder, Nature Com. 5, 3219, (2014)
  2. S. Perrard, M. Labousse, E. Fort, Y. Couder, Phys Rev Lett, 113, 104101, (2014).

Yves Couder in YouTube video

Yves Couder. Explains Wave/Particle Duality via Silicon Droplets [Through the Wormhole] (YouTube)

Morgan Freeman's "Through the Wormhole" on the Science Channel (season II, episode VI). How Does The Universe Work?

Mon, 09 Nov 2015 10:21:31 +0100

October 23

Michael Kachelriess, Department of Physics, NTNU
«2015 Physics Nobel Price: The discovery of neutrino oscillations»

October 23

Michael Kachelriess, Department of Physics, NTNU
«2015 Physics Nobel Price: The discovery of neutrino oscillations»

Abstract

2015 Physics Nobel Price: The discovery of neutrino oscillations

A review on the basics of neutrino oscillations  will be given, discussing both the (chain of) experiments that led to their discovery and the theoretical background. Most of the presentation should be accessible for everybody having followed a quantum mechanics course.

Mon, 09 Nov 2015 10:20:50 +0100

October 30

Arne Skjeltorp, IFE/Department of physics, UiO
«Magnetic micro- and nanoparticle manipulation and applications»

October 30

Arne Skjeltorp, IFE/Department of physics, UiO
«Magnetic micro- and nanoparticle manipulation and applications»

Abstract

Magnetic micro- and nanoparticle manipulation and applications

The talk will describe historical and recent advances in magnetic particle separation and manipulation using very forceful magnet systems. In 1976, John Ugelstad at NTH – now NTNU, first succeeded in making uniformly sized polystyrene microspheres. Later the microspheres were made magnetizable by depositing nanometer-sized iron oxide in pores inside the spheres. This achievement led to the invention of magnetic bead-based biomagnetic separation technology, in which the polymer surface of the beads is utilized for biological interaction site, while the magnetic components inside the beads are used for magnetic manipulation.

A new design of a magnet system denoted GIAMAG (GIant MAgnet field Gradient) has been realized with an unprecedented value of the product of the magnetic field strength B and the field gradient ∇B. This is crucial for rapid extraction of e.g. magnetic particles in dispersions as the magnetic force acting on magnetic particles is F ~ B x ∇B.

Existing magnet systems can just pull magnetic microparticles from solutions, whereas GIAMAG can extract magnetic particles down to nanosizes


Arne Skjeltorp

Senior Advisor, Physics Department, Institute for Energy Technology

Professor emeritus, Physics Department, University of Oslo

CTO, Giamag Technologies AS (Contactinfo. Arne Skjeltorp)

Mon, 09 Nov 2015 10:32:14 +0100

November 6

Ludwik Leibler, Matière Molle et Chimie, ESPCI ParisTech
«Nanoparticles dispersions as adhesives for gels and biological tissues»

November 6

Ludwik Leibler, Matière Molle et Chimie, ESPCI ParisTech
«Nanoparticles dispersions as adhesives for gels and biological tissues»

Abstract

Nanoparticles dispersions as adhesives for gels and biological tissues

Adhesives and glues are made of polymers. We introduce a novel concept of adhesion by particle solutions. We will demonstrate that to make a strong junction between two surfaces it suffices to spread a drop of a particle solution on one surface and press the other into a contact for few seconds. We will show the efficiency of the method, which we call nanobridging, for natural and synthetic hydrogels and various sorts of particles such as silica or iron oxide. We then extend the concept of nanobridging to biological tissues and demonstrate that the method can be used in vivo to close wounds even for soft organs such as liver and in hemorrhagic conditions. We will also show how particles can be used for hemostasis after organ resection. The approach proved easy to apply, rapid and efficient in situations when conventional methods of suturing or stapling are traumatic or fail.

Professor Ludwik Leibler has been awarded the European Inventor Award 2015 as one result from this work; CNRS researcher Ludwik Leibler receives the European Inventor Award 2015 (CNRS Press releases)

Wed, 28 Sep 2016 11:34:51 +0200

November 13

Noushine Shahidzadeh, University of Amsterdam, Netherlands
«The pressure induced by the growth of salt crystals in confinement»

November 13

Noushine Shahidzadeh, University of Amsterdam, Netherlands
«The pressure induced by the growth of salt crystals in confinement»

Abstract

The pressure induced by the growth of salt crystals in confinement

The precipitation of salt minerals in confinement (e.g. pores in porous media) is known to severely damage buildings, to be responsible for the weathering of rocks and to reduce the permeability in oil reservoirs. In all of these cases, crystal growth occurs within the pore spaces of the material, inducing mechanical stresses on the scale of the individual grains or pores. A condition for damage to occur is that the crystal continues to grow even in confinement, and that the resulting stress damages the rock or stone.

Arguments explaining that growing crystals can exert a pressure have been given for more than 150 years; however the mechanisms are still heavily debated since according to both Riecke’s principle and crystal growth theories, a mechanically constrained crystal because of its higher solubility should dissolve rather than exert a pressure. Consequently, for understanding the deterioration mechanism of crystal growth, a direct measurement of the crystallization pressure exerted by growing crystals is needed. This is a challenging problem as illustrated by the small number of experimental results reported in the literature.

We present a novel method that we have developed in order to directly measure the pressure exerted by a growing microcrystal in a confined geometry under controlled environmental conditions. This new method allows us to follow simultaneously the nucleation and spontaneous growth of the crystal from the salt solution and to measure the subsequent pressure developed at the pore scale. The important role played by the wetting properties and the nature of the salt on the development of a pressure during the growth will be discussed.

Abstract

The pressure induced by the growth of salt crystals in confinement [pdf]

Thu, 24 Sep 2015 16:19:41 +0200

November 20

Dimitri Argyriou, Director for Science, European Spallation Source (ESS), Sweden
«The Science Programme at ESS: Perspectives and Current Status»

November 20

Dimitri Argyriou, Director for Science, European Spallation Source (ESS), Sweden
«The Science Programme at ESS: Perspectives and Current Status»

Abstract

The Science Programme at ESS: Perspectives and Current Status

The civil construction of the European Spallation Source is well underway in the outskirts of Lund Sweden with great progress been realised so far. Likewise technical work to complete the facility is progressing well with the anticipation that component deliveries will meet schedule. The scientific programme at ESS has made significant advances in the last 18 months. ESS and it’s partners have defined a moderator-reflector package and target station layout that will provide both for capability and capacity to meet the needs of the neutron science community. Several instrument projects have began while the instrument selection process that will define the instrument suite to be build as part of the ESS construction is coming to its conclusion. With the science programme now defined our focus and that of our partners is shifting into delivery of the science programme.

I will provide an overview of the current progress of the science programme at ESS, the scientific opportunities that it will offer and how we are meeting the challenges that lie ahead.

Wed, 28 Sep 2016 11:35:40 +0200

November 27

Angelo di Bernardo, Cambridge University

«Signatures of spin-polarised superconducting states at superconductor/ferromagnet interfaces»

November 27

Angelo di Bernardo, Cambridge University

«Signatures of spin-polarised superconducting states at superconductor/ferromagnet interfaces»

Note: Talk starts at 13:15

Abstract

Signatures of spin-polarised superconducting states at superconductor/ferromagnet interfaces

The interaction between materials with radically different properties can lead to the emergence of tantalising physical phenomena.

A classical example of such an interaction is that occurring at a superconductor/ferromagnet (S/F) interface where an unconventional – odd frequency spin-triplet – superconducting state can arise and support a net spin-polarization [1].

The spin-polarization stems from the fact that, in the presence of an inhomogeneous magnetisation, the Cooper pairs form in a spin-triplet state in which the electron spins are parallel with a pair wavefunction that is odd in symmetry with respect to exchange of time coordinates [2].

Although evidence for odd-frequency states in S/F systems has been experimentally demonstrated via transition temperature measurements of S/F1/F2 spin valves [3-4] and supercurrent measurements in S/F/S Josephson junctions [5-7], spectroscopic evidence is inconclusive.

In this talk, I will discuss our recent spectroscopic experiments that provide direct evidence for odd-frequency spin-triplet superconductivity in superconducting densities of states of various S/F systems.

One experiment [8] involves scanning tunnelling microscopy on epitaxial layers of Nb proximity-coupled to single crystal Ho, where a low-temperature subgap structure in the superconducting density of states is observed and can be correlated to the magnetisation structure of Ho.

The second result [9] concerns a low-energy muon implantation experiment on Au/Ho/Nb, where an inverse (paramagnetic) Meissner response in Au is observed.

References

  1. J. Linder, J.W.A. Robinson, Nat. Phys. 11, 307 (2015)
  2. F.S. Bergeret, A. F. Volkov, K.B. Efetov, Rev. Mod. Phys. 77, 1321 (2005)
  3. P. V. Leksin et al., Phys. Rev. Lett. 109, 057005 (2012)
  4. X. L. Wang et al., Phys. Rev. B 89, 140508(R) (2014)
  5. T. Khaire et al., Phys. Rev. Lett. 104, 137002 (2010)
  6. J.W. A. Robinson et al., Phys. Rev. Lett. 104, 207001, 458 (2010)
  7. J.W. A. Robinson, J. D. S. Witt, M. G. Blamire, Science 329, 59 (2010)
  8. A. Di Bernardo et al., Nat. Comm. 6, 8053 (2015)
  9. A. Di Bernardo et al., Phys. Rev. X 5, 041021 (2015)
Wed, 28 Sep 2016 11:36:08 +0200
Mon, 23 Nov 2015 08:46:18 +0100