Physics Colloquium

Fall 2014

Thursdays 4:00 p.m., Room 104 Physics
Refreshments served at 3:40 p.m.
  Colloquium organizer: Julia Medvedeva
(Link to main colloquium page)

Green - open date
Yellow - tentative (reserved)
Red - firm commitment

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Date Host Speaker Title of the talk Abstract
Aug. 28
Oscar de Lucio (UNAM, Mexico City)
Applications of the 5.5 MV Van de Graaff Accelerator at IF-UNAM
for IBA techniques
Over the last three decades the 5.5 MV Van de Graaff accelerator at IF-UNAM has been commissioned for materials analysis, establishing several collaborations with a variety of research groups. Recently, a major upgrade has been performed allowing the use of more beamlines and the inclusion of a variety of new research projects. Some examples of the applications and current research performed at the Van de Graaff accelerator will be presented, with particular emphasis on the use of Ion Beam Analysis (IBA) techniques for materials characterization. Results from such techniques allow the quantification of elemental profiles in diverse samples, and has proven to be a unique and powerful tool specially for the measurement of light elements such H, Li, C, N, O.
Sept. 4

Sept. 11 Medvedeva
Alexander Goldberg (Schrödinger Inc.)
Schrödinger High-throughput Atomic Scale Simulations to Discover New Materials for Industrial Applications
With the rapid increase in computer power, molecular modeling with its virtual screening paradigm has a great potential for discovering and optimizing material solutions for diverse industries. For example, recently Professor Thompson of the University of Southern California used Schrödinger simulation tools to evaluate 205,000 organic compounds for use in photovoltaic devices. This work would have taken 264 years on conventional computers but was finished in 18 hours by running on 156,000 cores simultaneously, opening a new era in scientific computing. To date the number of studies applying first-principles calculations in a high-throughput fashion is limited; however with the fast advances in multicore computers and the availability of temporary cloud resources, virtual screening will become indispensable instrument in a search for new materials in many industrial applications. In this presentation, an overview of the Schrödinger Materials Science Suite is given and the use of high-throughput quantum chemistry to analyze and screen a chemical structure library is demonstrated for key materials applications including organic light-emitting diode (OLED), precursors for Atomic Layer Deposition (ALD) and materials for hydrogen storage and transportation.
Sept. 18
Department meeting

Sept. 25

Oct. 2
Risheng Wang (Chemistry, Missouri S&T)
DNA Engineering: From Structure to Application
Deoxyribonucleic acid (DNA), as you may very well know, is the carrier of generic information in living cells, which can replicate itself through Watson-Crick base paring. However, over the past three decades, researchers in the emerging field of DNA nanotechnology have been using the DNA as structural nanomaterials, based on its unique molecular recognition properties and structural features, to build addressable artificial nanostructures in one, two and three dimensions [1,2]. These self-assembled nanostructures have been used to precisely organize functional components into deliberately designed patterns which have a wide application potential in material science, biomedical, electronic and environmental fields [3].
The development of DNA nanotechnology and its potential application will be introduced first. Then my talk will focus on the design and construction of several DNA nanostructures, including 1) self-assembly of DNA six-helix nanotubes from two half-tube components. The main advantage of this assembly strategy is that it can provide a hollow system to conveniently sheath other components, which makes such nanotubes ideal candidates to serve as scaffolds to organize and control tubular materials for biomedical and electronic applications. 2) Using DNA origami template to organize semiconducting quantum dots (QDs) and gold nanoparticles (AuNPs). The controllable assembly of heterogeneous nanomoeities opens new opportunities for the creation of complex nanoassemblies, which can display unique properties based on programmable interactions between electro-optically active constituents. 3) Discussing the techniques of combining lithographic patterning with bio-molecular assembly to produce highly ordered, self-assembled arrangements of nano-objects. This integration of “top-down” nanofabrication technique and “bottom-up” self-assembly is opening new opportunities for the creation of devices and circuits in nanoscale.

1.    N. C. Seeman, Mol Biotechnol, 2007, 246-257.
2.    A. V. Pinheiro, D. Han, W. M. Shih and H. Yan, Nature Nanotechnology, 2011, 763-772.
3.    F. A. Aldaye, A. L. Palmer and H. F. Sleiman, Science, 2008, 1795-1799.
Oct. 9
Pouyan Ghaemi (CUNY)
Electronic world on the edge
The band structure of a solid, one of the most important results of quantum theory, explains
the relationship between the energy of electrons and the quantum wave-vector that labels
their state. The band structure is the basic foundation for understanding the properties
of semiconductors, which, for instance, has been responsible for much of the development
in the electronics industry. We now know that the electronic band structure contains more information than solely the relationship of energy and wave-vector of electrons. This information which is stored in quantum wave function of  electrons in solids distinguishes many new electronic phases with novel properties. In many cases the signature of these new phases appears as the robust electronic edge states. These edge states are realized in easily accessible conditions and present a macroscopic signature of quantum theory. In this talk I discuss some examples of solids with such robust electronic edge state, the novel electronic phases that can be stabilized on the edge of these materials and how they can open the door for new applications.
Oct. 17 Madison
Homecoming: Matthew Foster
Aircraft Carriers, Bytes, and Physics: The Fate of a Missouri S&T Physicist
Matthew Foster discusses the transition from a budding atomic physicist into a rebellious operations research scientist. He shares his journey from the high desert of Los Alamos, NM, through the picturesque views of Bagram, Afghanistan, and ending at shores of Hampton Roads, VA. In 2008, Matthew semiofficially retired as a physicist and joined the Center for Naval Analysis (CNA), the U.S. Navy’s Federally Funded Research and Development Center (a.k.a. think tank). During World War II, German U-boats plugged and ravaged American shipping lanes, halting supplies to Europe.  The U.S. Navy enlisted MIT professor Philip Morse, the first CNA field representative — Matthew’s current position — and founder of modern operations research (OR). Morse led the scientific team that developed effective escort screening plans and designed antisubmarine warfare tactics. Matthew accounts classic operation research problems and modern examples from his personal experiences in Operation Enduring Freedom. Finally, he brags about his degrees of separation between himself and the White House via the classic, now cheesy, 1980’s movie Top Gun.
Oct. 23 Hor
David Hseih (Caltech)
Quantum states of matter in crystals
We have all encountered the three classical states of matter: solid, liquid and gas. But what is a quantum state of matter, where do we find them and what are they good for? In this talk we will explore the behavior of electrons in crystals and examine how the interactions between electrons and their crystalline host can generate a large variety of unusual states of matter that exhibit macroscopic quantum properties. Exactly which crystals to search in, their potential technological applications and practical feasibility will all be addressed.
Oct. 30
Otmar Schmid
Aerosol Science in Health Research
– or –
What the Heck Can You Do with Cloud and Aerosol Science?
With every breath inhaled aerosol is depositing in the lung. The fate and biological effects of these particles depend on physiological parameters mechanisms and the properties of these particles such as size, shape and material. Obviously, inhalation of aerosols can be friend and foe: While therapeutic aerosol offers attractive options for non-invasive pulmonary and systemic drug delivery, the exposure to potentially toxic aerosol such as soot or engineered nanomaterial raises health concerns.
These issues are studied in model systems of biology such as cell systems, tissue slices and organs as well as animal models. One of the most ambitious projects in this field is the design of an in-vitro organism consisting of a network of bioreactors representing the various organs using organ-specific cells. Ideally, these in-vitro organisms could make substance testing on animals obsolete. Cloud and aerosol science is an essential part of this highly interdisciplinary research field as evidenced by awarding the Nobel Prize 2002 in Chemistry to John Bennett Fenn for discovering that electrospray aerosolization allows for soft ionization and subsequent mass spectrometric analysis of biological samples without fragmentation of biological macromolecules.
In this presentation various examples of the essential role of aerosol science in health research is given with an emphasis on my own work during the past decade. The focus will be on innovative methods of aerosolized drug delivery to cell systems, animal models and patients as well as the assessment of toxicological effects of inhaled nanoparticles and recent advances in in-vivo imaging of the bioactive pulmonary drug dose in small animals.
Nov. 6
Nicholas Butch (NIST Center for Neutron Research)
Adventures in electron correlations
Sitting at the bottom of the periodic table, the lanthanide and actinide elements may seem like a dreary bunch, but they are responsible for some of the most interesting phenomena in condensed matter physics. At the heart of it all is the complicated manner in which the f-electrons interact with other electrons.  I’ll discuss two of the more unusual cases of current interest: Kondo topological insulators and hidden order.
Nov. 13
Kurter Aaron Finck (UIUC) Searching for Majorana Fermions in Hybrid Topological Insulator Devices through Interferometry
Topological superconductors have been predicted to host exotic bound states commonly referred to as Majorana fermions, which possess non-Abelian exchange statistics.  One can engineer a topological superconductor by coupling a conventional s-wave superconductor with the helical surface states present in a topological insulator.  In this talk, I will describe our efforts to probe unconventional superconductivity using phase coherent transport in topological insulator interferometers with superconducting leads.  We observe prominent Fabry-Perot oscillations that become strongly modified at low energies due to Andreev reflection.  At high magnetic fields, we detect periodic $\pi$ phase shifts in the Fabry-Perot oscillations that can be linked to the intrinsic Berry phase of the helical surface states.  We relate these observations to the on-going search for Majorana fermions in solid state systems.
Nov. 20
Reuben Collins (Colorado School of Mines)
Hot carrier transfer in nanocrystalline silicon
The optical and electronic properties of semiconductor quantum dots have generated considerable scientific and technological interest. Nanocrystalline silicon, which consists of silicon quantum dots embedded in an amorphous silicon matrix, is, in some sense, one of the earliest of these nanomaterials.  It has applications extending from photovoltaics to thin film transistors.  We have recently discovered unexpected carrier dynamics in this system. Charges photoexcited in the amorphous region transfer to quantum dots before relaxing into localized states; a form of hot carrier transfer.  This observation provides insight into interesting properties of nanocrystalline silicon. This talk will introduce nanocrystalline silicon, discuss its properties, and present new approaches for synthesizing material with controllable quantum dot size in the sub 10nm regime.
Dec. 4
Eighteenth Annual Laird D. Schearer Prize Competition

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