Events: Nanovetenskap och nanoteknik events at Chalmers University of TechnologyMon, 21 May 2018 11:47:44 +0200é-Carmelo.aspx by José Carmelo<p>Lunchroom, Soliden floor 3</p><p>Seminar by Professor José Carmelo, University of Minho, Portugal Title: Effects of long-range interactions on spectral properties of low-dimensional systems</p><h4 class="chalmersElement-H4">Abstract:</h4> <div>A transformation that accounts for the universality found in Ref. [1] concerning the spectral functions of both integrable and non-integrable one-dimensional (1D) correlated systems is used to generate from the pseudofermion dynamical theory of the integrable 1D Hubbard model [2], which relies on a suitable rotated-electron representation [2,3], a corresponding renormalized theory with additional electron finite-range interactions [4]. An improved version of the latter theory that accounts for long-range interactions is used to describe the experimental spectral lines in the angle resolved photoemission spectroscopy (ARPES) of two low-dimensional systems: The quantum line defects in the two-dimensional van der Waals layered semiconductor MoSe2 [4] and an anisotropic InSb(001) surface covered with Bi [5]. The theoretical predictions refer to high-energy windows in the vicinity of the peaks of the observed spectral lines. For the parameters values for which the predicted peaks distribution agrees with that in the ARPES images, the low-energy power-law density of states suppression exponent α is given by α ≈ 0.72−078 for the MoSe2 line defects [4] and α ≈ 0.60 − 0.70 for Bi/InSb(001) [5], in agreement with their experimental uncertainties.</div> <div>(For the 1D Hubbard model, α &lt; 1/8).</div> Reginald Penner and Laura Lechuga<p>PJ, lecture hall, Fysik Origo, Fysik</p><p>Seminar 1: 10.00-10.40 Biosensors for early cancer detection based upon electrical interfaces to virus particles. Professor Reginald Penner, University of California, Irvine, USA Seminar 2: 10.40-11.20 Nanophotonic biosensor platforms for ultrasensitive bioanalysis. Professor Laura Lechuga, Catalan Institute of Nanoscience and Nanotechnology, Barcelona, Spain</p><h4 class="chalmersElement-H4">Abstract:</h4> <div><strong>Seminarium</strong><strong> 1:</strong> Biosensor technologies that enable the rapid measurement of disease biomarkers in unprocessed biological samples, including blood, urine, saliva, and cerebrospinal fluids, remain elusive and highly sought after. The ultimate goal are devices that can be used with minimal training by physicians and patients to provide actionable information at the point-of-care (PoC). In addition to simplicity, analysis speed and sensitivity are critically important metrics for PoC biosensors but the technology must also provide for sensor-to-sensor reproducibility, manufacturability, and low cost. A new approach to PoC detection of protein disease markers involves the use of virus particles, rather than antibodies, within a bioaffinity capture layer.  Relative to antibodies, virus particles have several advantages that make them attractive for emerging PoC sensor technologies:  First, virus particles can be engineered to bind virtually any protein – even toxic proteins for which antibody development is difficult.  Second, virus particles are less thermally and chemically labile than antibodies, dramatically simplifying the storage and transport of biosensors that rely on virus–based bioaffinity layers. Finally, virus particles that are capable of antibody-like affinities can be produced in quantity for far lower cost. In this talk I describe a PoC biosensor that exploits electrodeposited bioaffinity layers that consist of a composite of virus particles with an electrically conductive polymer, poly(3,4 ethylenedioxythiophene) or PEDOT. <br /><br /><strong>Seminarium</strong><strong> 2</strong><strong>:</strong><br />Motivated by potential benefits such as sensor user-friendly, multiplexing capabilities and high sensitivities, nanophotonic point-of-care biosensor platforms have profiled themselves as an excellent alternative to traditional analytical techniques. The main objective of our research is to achieve ultrasensitive platforms for label-free analysis using nanophotonic technologies and custom-designed biofunctionalization protocols, accomplishing the requirements of disposability and portability. We are using innovative designs of nanophotonic biosensors based on silicon photonics technology (bimodal waveguide nanointerferometers) or nanoplasmonics (gold nanostructures) and full microfluidics lab-on-chip integration. We employ dedicated biofunctionalization routes of the biological receptors (as proteins or genomic strands) ensuring selectivity, life-cycle, non-fouling properties and reusability. We have demonstrated the suitability of our photonic nanobiosensors for the detection, with extremely sensitivity and selectivity, of environmental pollutants and human disease biomarkers. In all cases, our sensing methodology has shown excellent robustness with high reproducibility and sensitivity, rendering in valuable tool for the fast diagnostics of un-treated bodily fluids or environmental samples.</div> about Teaching and Learning<p>PJ, lecture hall, Fysik Origo, Fysik</p><p>Organiser: Gothenburg Physics Centre</p><p>Programme: To be announsed</p> by Axel Brandenburg<p>PJ, lecture hall, Fysik Origo, Fysik</p><p>​Seminar by Axel Brandenburg, Nordita Title: Magnetohydrodynamic field generation</p><h4 class="chalmersElement-H4">Abstract:</h4> <div>Magnetic fields are prominent players in virtually all areas of astrophysics, Theory and simulations demonstrate their exponential growth starting from weak seed magnetic fields that, in turn, are generated by some battery term. This is the self-excited dynamo, a tremendously important concept for the utilization of electricity since the works of Wheatstone, von Siemens, and Varley of 1866. Homogeneous self-excited dynamos, which do not have wires, are susceptible to short-circuiting themselves. Although anticipated already 99 years by Larmor, it was only since the 1970s that astrophysical dynamos became theoretical and numerical reality and not just ideas. Since 2000, experimental realizations have begun to expand our understanding into corners of parameter space not yet accessible to simulations.</div> <div> </div> <div>In my talk, I will highlight the concepts of small-scale and large-scale dynamos, the dependence on the ratio of viscous to resistive dissipation, the inverse turbulent cascade of magnetic helicity, and new classes of large-scale dynamos beyond just helical ones. In density-stratified systems, cross helicity, characterizing the linkage between magnetic and vortex tubes, plays a rote in producing spots, perhaps like those seen on the Sun. In spite of much progress, though, we are still not sure how exactly the solar dynamo works, whether primordial magnetic fields play a role in galactic magnetism, and whether such primordial fields are perhaps even fully helical.</div> Physics Colloquium: Lene Vestergaard Hau<p>Lecture hall FB, Origo building, Fysikgården 4, campus Johanneberg</p><p>Title of talk: The art of taming light: What we can learn from a bacterium… and beyond. Special Physics Colloquium by Professor Lene Vestergaard Hau, Harvard University, USA</p>