Department Seminars
08 April 2013
Last Updated on Wednesday, 24 April 2013 10:01
Department Seminar: Friday, April 26, 2013
Superatoms: New Nanoscale Materials Using New Building Blocks
Dr. S. N. Khanna
Size selected stable clusters have electronic shells like atoms offering them the potential to mimic the physics and chemistry of elements in the periodic table and be regarded as “superatoms” forming a third dimension to the periodic table. The talk will focus on this intriguing discovery and its implication for creating novel nanoscale materials with tunable characteristics. Specific examples illustrating how the clusters of the most easily oxidized solids can display extreme resistance to oxidation, clusters with specific geometry that can split water to generate hydrogen on demand, and clusters that display novel magnetic properties will be presented. Recent protocols that enable us to synthesize materials from the new building blocks will be discussed. Finally, the talk will present applications of nanoparticles to design non-rare earth permanent magnets and to medical areas, specifically contrast imaging and treatment of brain tumors.
- Zhang, X., Wang, Y., Wang, A., Lim, G., Gantefor, G., Bowen, K.H., Reveles, J.U., and Khanna, S. N., “On the existence of Magnetic Superatoms”, JACS, ASAP (2013).
- Qian, M.; Reber, A. C.; Ugrinov, A.; Chaki, N. K.; Mandal, S., Saavedra, H. C.; Khanna, S. N.; Sen, A.; Weiss, P. S.; “Cluster-Assembled Materials: Towards Nanomaterials with Precise Control over Properties”, ACS Nano 4, 235-240 (2010).
- Ulises Reveles, J.; Clayborne, P. A.; Reber, A., C.; Khanna, S., N.; Pradhan, K.; Sen, P.; and Pederson, M., R.; “ Designer magnetic superatoms”, Nature Chemistry 1, 310-315 (2009).
- Roach, P. J.; Woodward, W. H.; Castleman, Jr., A. W.; Reber, A. C.; Khanna, S. N.; “Complementary Active Sites Cause Size-Selective Reactivity of Aluminum Cluster Anions with Water”, Science 323, 492-495 (2009).
- Castleman, Jr., A. W. and Khanna, S. N. “Clusters, Superatoms and Building Blocks of New Materials”, Invited Featured Article for the Journal of Physical Chemistry,113, 2664-2675 (2009).
Friday, April 26, 2013
PSCI 208
3:00 pm
(Refreshments will be served from 2:45 pm to 3:00 pm)
Department Seminar: Friday, April 19, 2013
Optical devices and methods for retinal laser targeting and longitudinal imaging
Lasers can be utilized in powerful ways to realize both highly selective microsurgery and high-resolution, confocal imaging. Here, two research directions that explore the use of lasers for retinal therapy and retinal imaging will be discussed.
Selective laser targeting of the Retinal Pigment Epithelium (RPE), a potentially useful treatment modality for retinal diseases such as age-related macular degeneration, limits the exposure time of each cell to the thermal relaxation time of the absorbing structures. Thus, it minimizes heat diffusion into adjacent photoreceptors and avoids their thermal destruction. Because these selective laser lesions are invisible to the ophthalmologist, feedback based on the cell damage mechanism is crucial to ensure correct dosimetry for efficient irradiation while preventing over-treatment. The feasibility of identifying RPE cell death by detecting intracellular cavitation was demonstrated in rabbits with a laser scanner that monitors backscattering of the treatment laser beam during selective laser targeting.
Most current knowledge of retinal diseases has been gained from ex vivo and post-mortem examination, an obstacle to developing more efficient treatments. However, due to the transparency of the ocular media, the retina lends itself to direct optical in vivo microscopy. We have developed a scanning laser ophthalmoscope (SLO) specifically for retinal imaging in the mouse eye. The instrument acquires three-color images in real-time, allowing three distinct cell populations to be tracked simultaneously and repeatedly. We are able to resolve retinal microstructure, such as retinal ganglion cells and microglia, the retinal neurons and immune cells, respectively. Spatio-temporal response of microglia to retinal injury models of focal laser injury and gamma irradiation is studied, employing real-time and time-lapse imaging.PSCI 208, 3:00 pm
Department Seminar: Friday, April 12, 2013
Life after Stellar Death: Challenges for Computational Astrophysics
Department Seminar: Friday, April 5, 2013
Heavy element synthesis in the Universe
UC Santa Cruz
The source of about half of the heaviest elements in the Universe has been a mystery for a long time. Determining whether these elements can be made in cataclysmic events requires extensive astronomical observation and sophisticated computer modeling.
Friday, April 5, 2013
PSCI 208, 3:00 pm
(refreshments will be served at 2:45 pm in front of PSCI 208)
Department Seminar: Friday, March 8, 2013
Computational Resources and Services to Facilitate Research and Education
- Provide an overview of the function of UTEP’s new Research and Academic Data Center and the Research Cloud @ UTEP;
- Describe the University of Texas Research Cyberinfrastructure initiative; and
- Introduce you to XSEDE, eXtreme Science and Discovery Discovery Environment, which is supported by the National Science Foundation.
Also, I am interested in hearing from you about how UTEP, the UT System, and XSEDE can better serve you in terms of computational resources and services.
Department Seminar: Friday, March 1, 2013
COMPACT ULTRA DENSE OBJECT (CUDO) IMPACTS
Dr. Johann Rafelski
University of Arizona
What if there are 'dark' matter meteor and asteroid-like bodies in the Universe? Could some of them have collided with solar system bodies and the Earth? CUDOs' high density of gravitating matter provides the distinct observable difference in the outcome of their collisions with rocky bodies, the surface-penetrating puncture, with only a fraction of the kinetic energy damaging the solid surface: the CUDO will practically always enter the target body, and many will exit the body -- such impacts are 'punctures.'
Department Seminar: Friday, February, 22, 2013
Quantum Transport in Graphene Membranes
Dr. Chun Ning (Jeanie) Lau
Professor of Physics and PECASE Award 2009
University of California, Riverside
Graphene, a two - dimensional single atomic layer of carbon, has recently emerged as a new model system for condensed matter physics, as well as a promising candidate for electronic materials. Though single layer graphene is gapless, bilayer and tri-layer graphene have tunable band gaps that may be induced by out-of-plane electric fields or arise from collective excitation of electrons. Here I will present our results on transport measurements in bilayer and tri-layer graphene devices with mobility as high as 400,000 cm2/Vs. We demonstrate the presence of an intrinsic gapped state in bilayer graphene at the charge neutrality point, evidence for quantum phase transition, and stacking-order dependent transport in tri-layer graphene. Our results underscore the fascinating many-body physics in these 2D membranes, and have implications for band gap engineering for graphene electronics and optoelectronic applications.
Department Seminar: Friday, February 15, 2013
Search for Heavy Partners of the Top-quark at the CMS experiment
Mr. Guillermo Breto-Rangel
University of California Davis
QCD predicts the existence of a high temperature state of strongly interacting matter, in the form of a hot plasma of deconfined quarks and gluons. The in-medium behavior of quarkonia (a bound state of a quark and its antiquark) can serve as a probe to determine the temperature of this quark-gluon plasma, in theory as well as in nuclear collision experiments. I summarize the results from the study of charmonium and bottomonium via the dimuon decay channel in PbPb collisions with the CMS experiment. I discuss the observation of sequential suppression of the Upsilon states. I present preliminary results of prompt J/psi and psi' production, as well as of non-prompt J/psi's coming from the weak decay of b-quarks. This latter measurement is sensitive to b-quark energy loss. I discuss the results and compare to model predictions.
Department Seminar: Friday, February 8, 2013
Search for Heavy Partners of the Top-quark at the CMS experiment
Dr. Ricardo Vasquez-Sierra
University of California Davis
At present, the Standard Model includes three generations of fermions. It is natural to ask whether there could be a fourth one. The existence of a fourth generation of fermions could help resolve the matter anti-matter asymmetry in the universe and could induce the heavy neutrino as a candidate for dark matter. The CMS experiment has searched for fourth generation quarks and a summary of these searches is presented in this talk. No significant excess of events over Standard Model expectations is observed, therefore upper mass limits on the existence of heavy quarks are set at 95% C.L.
Department Seminar: Friday, February 1, 2013
The Holometer: A Measurement of Geometry at the Planck Scale
Dr. Stephan Meyer
University of Chicago
Experiments confirm that quantum mechanics is correct, and that spatial locality is not a fundamental property of reality: nothing happens at a definite time or place. By contrast, the physics of space and time is based on the pre-quantum notion that bodies have definite positions and trajectories. This leads to distinct problems for ideas about physics at the Planck scale.I will describe the experiment we are currently constructing designed to inform theories on the Planck scale. We prepare and measure a coherent quantum state of position that is delocalized in space and time in two directions with Planck spectral sensitivity to position noise. When operating at its designed physical noise limit, it will either confirm or rule out coherent delocalized transverse entangled position noise with precision well beyond the Planck level.
Department Seminar: Friday, November 30th
STRAIN RATE EFFECTS IN SHOCK-INDUCED DEFORMATION OF SOLIDS
Dr. Ramon Ravelo
University of Texas at El Paso
Abstract:
Large-scale non-equilibrium molecular dynamics simulations are now commonly used to study material deformation at high strain rates (109-1012 s-1). They can provide detailed information such as defect morphology, dislocation densities, and temperature and stress profiles, unavailable or hard to measure experimentally. Computational studies of shock-induced plasticity and melting in simple metals exhibit generic characteristics: high elastic limits, large directional anisotropies in the yield stress and pre-melting much below the equilibrium melt temperature for shock wave propagation along specific crystallographic directions. For time scales relevant to dynamic shock loading, the directional-dependence of the yield strength in single crystals is shown to be due to the onset of instabilities in elastic wave propagation. With increase compression and strain rate, melting of the solid can proceed at temperatures significantly below the equilibrium melt temperature. It will be shown that under uniaxial straining the driving force for melting increases with strain rate. After melting, the vanishing of non-hydrostatic stresses leads to an undercooled and unstable liquid, which recrystallizes in picosecond time scales.
Department Seminar: Friday, November 16th
Properties of a Few Nanoparticles
Dr. Elaine Li
University of Texas at Austin
Abstract:
The properties of individual semiconductor and metallic nanoparticles have been extensively investigated. When multiple nanoparticles are arranged in a particular geometry, however, new and fascinating properties emerge. I will present a few recent experiments in which we assembled semiconductor/metallic nanoparticles into a particular geometry using AFM nanomanipulation.
Department Seminar: Friday, November 9th
Engineering Interfaces: Using Subtle, Nano-scale Changes to Tune Functional Properties in Next-Generation Electronic Devices
Katherine S. Ziemer, Ph.D.
Northeastern University Chemical Engineering Department, Boston MA, USA
Abstract:
Effective integration of functional oxides (magnetic, ferroelectric, piezoelectric and other multi-functional materials) with semiconductors will lead to next-generation devices such as: new architectures that enable multiple and simultaneous interactions with the environment for multifunctional active sensors and controllers; energy harvesting and conversion devices as part of everyday items from clothing to sidewalks; integrated nonvolatile memories for harsh environments; and paradigm-shifting spintronics-based circuits. Many of the functional properties of complex oxides are directional, thus requiring a specific plane alignment in a device, and most oxides have multiple stable structures for a given stoichiometry. In addition, small changes in stoichiometry with the same unit cell structure can produce easily measurable differences in performance properties. While this sensitivity enables the possibility of tuning complex oxides for different and novel applications, precise control of stoichiometry and structure (practically at the atomic-level for nanoscale thin film heterostrucutres) is required. This is particularly true for the interfaces and near-interface layers between the semiconductor and oxide as well as between subsequent functional oxide layers, because surface quality impacts chemistry, structure, and morphology of next-layer film deposition that, in turn, impacts the functionality of the film layer and the coupling effects across layers through critical interfaces. Through molecular beam epitaxy (MBE), the use of a magnesium oxide (MgO) template layer and the interface formation mechanisms of an oxygen bridge have been investigated for effective heteroepitaxy of high-quality ferroelectric barium titanate (BTO) and ferrimagnetic barium hexaferrite (BaM) on 6H-SiC. The results suggest strategies applicable to many functional oxide integrations and many processing techniques.
6H-SiC(0001) substrates are cleaned in an ex-situ hydrogen furnace which produces and atomically smooth, stepped surface with a √3×√3 R30° surface reconstruction, verified by reflection high energy electron diffraction (RHEED) and x-ray photoelectron spectroscopy (XPS). High quality, single crystalline MgO(111) is obtained with a smooth surface (RMS<0.5 nm) and a stepped morphology conformal to the underlying 6H-SiC morphology, but is inherently twinned due to the ionic nature of a (111) oriented rock salt structure. The smooth, conformal 2-D growth of MgO requires the presence of atomic oxygen in a Mg-adsorbsion controlled mechanism, and grows in tension with a 3.3% lattice mismatch. The engineered MgO surface is both effective and necessary to promote the pseudo-hexagonal heteroepitaxy of BTO(111) and BaM(0001). As an example, the epitaxy alignments for the BTO/MgO/6H-SiC results in a BTO{111}//MgO{111}//6H-SiC{0001} out-of-plane relationship and a BTO{11(bar)0}//MgO{11(bar)0}//6H-SiC{002(bar)1} in-plane relationship. The BTO layer of the heterostructure has ferroelectric properties with a saturated polarization around 4.7 mC/cm2 and an apparent striped domain structure. Tunneling Electron Microscope analysis reveals subtle bond angle differences in the first layer of atoms at the interface that lead to subsequent micron-scale features in the final film layers. Understanding the subtle impacts of nano-scale interface structures on the measureable performance of micron-scale materials will be critical to next-generation engineered composites and multifunctional devices.
Department Seminar: Friday, November 2nd
The Many Phases of Matter inside Neutron Stars
Dr. Fridolin Weber
San Diego State University
San Diego, CA
Abstract:
Neutron stars contain matter in one of the densest forms found in the Universe. This feature, together with the unprecedented progress in observational astrophysics, make such stars superb astrophysical laboratories for a broad range of physical studies which are intimately linked to the structure of matter inside neutron stars. In this talk I will provide an overview of a variety of such studies which concern the structure of matter ranging from core to crust. Particular emphasis will be put on studies that focus on the role of strangeness, as carried by hyperons, mesons, and color superconducting quark matter.
Department Seminar: Friday, October 26th
Cosmological Scale Tests of General Relativity
Dr. Edmund Bertschinger
Professor of Physics and Physics Department Head
Massachusetts Institute of Technology
We do not know the cause of cosmic acceleration. A century ago, the correct answer to then-surprising observations of planetary motions was to modify the prevailing theory of gravity. Confirmation of the new theory of general relativity came in 1919 through comparison of the motion of planets and light in the sun's gravitational field. Today we are called again to test general relativity on much larger length scales in light of the surprising observation of cosmic acceleration. General relativity can be tested on cosmological scales by comparing the motion of galaxies and light. Preliminary tests support general relativity but much better tests will be possible with future large surveys of galaxy clustering and weak gravitational lensing.
Department Seminar: Friday, October 12th
Astronomy at the Top of the World:
Can We See Gravitational Waves From There?
Mario Díaz
Over the past few years the astronomical community have promoted a method called Multi-messenger astronomy. Multimessenger Astronomy refers to the combined effort of different instruments and scientists to understand and study complementary information for the same astrophysical event. With the advent of Advanced LIGO and the new generation of gravitational wave detectors Multi-messenger Astronomy will become a very rich reality. In this colloquium I will explain how optical astronomy can complement gravitational wave detection through modern interferometers. I will briefly comment on efforts already started during the last LIGO scientific run involving several telescopes around the world and I will then describe a pilot project at UTB to install an optical observatory in the high Andes mountains of the Argentine Atacama region, and the plan to join a multi-messenger astronomy effort before and during advanced LIGO.
Department Seminar: Friday, September 28th
Department Seminar: Friday, September 14th
Investigation of Possible Modification of Proton and Pion Production in Jets from √sNN = 200 GeV Au+Au Collisions at STAR
Friday September 14, 2012
3:00 pm
PSCI 208
Abstract
The Relativistic Heavy Ion Collider (RHIC) located at the Brookhaven National Laboratory produces Au + Au collisions at a high center of mass energy per nucleon pair (√sNN = 200 GeV ). The heavy ion program at RHIC was designed to study a state of matter consisting of de-confined quarks and gluons (Quark Gluon Plasma) under conditions of high temperature that might be created in heavy ion collisions. The hadron spectra produced in Au +Au collisions with a small impact parameter does not follow a simple superposition of nucleon-nucleon collisions. High transverse momentum (PT) particle yields get suppressed in those collisions. The depletion of high PT particles is accompanied by an enhancement of low PT particles as can be measured by relative azimuth correlations of high PT trigger hadrons or jets with respect to lower PT associated hadrons. Theproduction of protons and pions in central heavy ion collisions differs from vacuum fragmentation. Inclusive proton/pion ratios show an enhancement at intermediate transverse momentum (PT ~1.5 - 4.0 GeV/c) in central √sNN = 200 GeV Au+Au collisions compared to peripheral Au+Au and p+p collisions. This effect suggests a production mechanism, different from fragmentation, which is consistent with coalescence and recombination models. In the present study a high-ET trigger particle selects a surface-biased jet, which is measured to have a similar PT distribution as a p+p jet. This jet is used to enhance the quenching effects of the recoiling, medium traversing one. We reconstruct the trigger jet using the Anti-kt jet finding algorithm, with an ET (PT) cut of 3.0 GeV (/c) on the towers (tracks) in order to reduce the heavy-ion collision background. The particle identification of tracks with PT up to ~ 2.8 GeV/c is obtained by taking advantage of the Solenoidal Tracker at RHIC(STAR) Time of Flight and Time Projection Chamber detectors with full azimuth coverage. Correlations in Δ between jets and identified hadrons are presented, and the particle ratios in different regions of azimuth are measured. Particle ratios associated with the trigger jet vs. the recoil jet, and comparisons to inclusive particle ratios can help to distinguish between jet- related (vacuum and medium-modified) and bulk-related contributions to the ratios enhancement.
First Department Seminar of 2012-2013!
Dr. Iwan Kityk
Photoinduced Nonlinear Optical Effects in Condensed Matter
Thursday, August 30, 2012
1:30 pm
PSCI 115
Abstract
The phenomenological and microscopical aspects of laser operation by optical and nonlinear optical susceptibilities will be considered. Among the materials the large spectrum of disordered materials (glasses, nanocomposites, , metallic, amorphous organic and inorganic compounds) will b considered. The role of local hyperpolarizablities and surrounding matrices will be studied. Coherent and non-coherent laser stimulated methods of formation non-centrosymmetry together with corresponding nonlinear optical phenomena will be given. Role of different dopants in the low-dimensional particles and particularly role of localised rare earth doping will be considered. The principal role of rare earth doping on the enhancement of laser induced efficiency will be shown using experimental methods of photoinduced second harmonic generation, third harmonic generation and two-photon absorption. Consideration of the surfaces and nano-interfaces in the output optical susceptibilities will be given. For the crystals the photoinduced operation by optical and dielectric constants is possible only for the rare earth doped materials. Role the rare earth polarizations and excitation of the localised f-d orbital in the effect will be considered. The contribution of the electron-phonon interaction and especially anharmonic ones and their relations with surface Plasmon resonances will be considered. The observed phenomena allow to use the proposed methods for dynamical operation by the physical and chemical features of corresponding materials. It is shown a possibility to operate by the properties of one manufactured composites using external laser light. The principal factors restraining the wide application of the laser induced methods are: light scattering, photodestruction, relaxation. Possible ways of improvement the technological parameters is shown.
Department Seminar: Friday, April 13th:
SESAME – A THIRD GENERATION LIGHT SOURCE FOR THE MIDDLE EAST
Abstract:
Developed under the auspices of UNESCO & modeled on CERN, SESAME (Synchrotron-light for Experimental Science and Applications in the Middle East) is an international research center in construction in Jordan. It will enable world-class research by scientists from across the Middle East/Mediterranean region (in subjects ranging from biology and medical sciences through materials and environmental science and physics, to archaeology), preventing or reversing the brain drain. It will also build bridges between diverse societies, contributing to a culture of peace through international cooperation in science. The centerpiece of SESAME is a new 2.5 GeV 3rd Generation Electron Storage Ring/Light Source (133.2m circumference, 26nm-rad emittance and 12 places for insertion devices), which will provide very intense light from infra-red to hard X-rays for a wide range of studies, including regional biomedical and environmental issues, and studies of local archaeological objects. SESAME offers excellent opportunities to train local scientists and attract those working abroad to return. The project is governed by a Council which currently meets twice each year and presently has nine Members (Bahrain, Cyprus, Egypt, Iran, Israel, Jordan, Pakistan, Palestinian Authority, and Turkey). Other countries are expected to join. The president of the Council from 1999-2008 was Herwig Schopper. Sir Chris Llewellyn-Smith is now President. Both are former Directors-General of CERN. Members have collective responsibility for the project and provide the annual operations budget (~$2.2 million in 2011 and expected to rise to $5.7-8.5 million when operation starts in 2015). Jordan provided the site, building, and infrastructure. A staff of 21 is now installing the refurbished 0.8 GeV BESSY I injector system, a gift from Germany. The pre-injector 22 MeV microtron is already in operation. The facility will have the capacity to serve 25 or more experiments operating simultaneously. Decommissioned beamlines, which will be upgraded and refurbished to provide the basis for five of the seven Phase 1 SESAME beamlines, have been provided by the Daresbury laboratory in the UK, the Helmholtz Association in Germany (this beamline was in use at the European Synchrotron Radiation Facility), the Swiss Light Source, and LURE in France. Beamline components and other equipment have been provided by the University of Liverpool, Elettra in Italy and US labs. Jordan has contributed $3.3 million, in addition to the building and land, and the European Union has contributed $4.8 million. The Members are currently finalizing arrangements to fund the final stage of construction. A training program in the use of beamlines, and on accelerator technology and scientific applications, has been underway since 2000, funded by the International Atomic Energy Agency (IAEA), the Abdus Salam International Centre for Theoretical Physics (ICTP), the Japanese Society for the Promotion of Science (JSPS), the Portuguese Foundation for Science and Technology (FCT), the US Department of Energy, and fellowships by synchrotron radiation laboratories around the world. The laboratory is managed by a Director, together with Scientific, Technical and Administrative Directors. Construction of the shielding wall and of the tunnels where the accelerators are to be installed has been completed. Four Advisory Committees advise the Council and work with the staff on the technical design, beamlines, training and scientific programs. A “soft” inauguration (marking building completion, staff occupancy, & start of installation of the injector) was held on November 3, 2008, with the Director-General of UNESCO, a representative of the King of Jordan, and many dignitaries present. SESAME is on track for a research start in 2015.
Department Seminar: Tuesday, April 3:
Dependence of the vibrational entropy of iron binary alloys on their atomic configuration
Abstract:
The accurate prediction of the most stable phase at given conditions so far has been elusive, mostly because it is difficult to include all the possible sources of entropy in a calculation. The properties of a material depend on its phase, though, so it is paramount to the computational design of materials to be able to make this prediction. Vibrational entropy, originating from atomic vibrations (phonons), makes major contributions to the free energies of alloy phases and their relative thermodynamic stabilities. A more elaborate understanding of the factors that affect the vibrational entropy is therefore an important step towards the prediction of stable phases.
In this talk I will show how the electronic structure affects the vibrational entropy and phonon thermodynamics of ordered and disordered binary alloys of iron with other first row transition metals. Accurate phonon densities of state (DOS) curves were obtained by combining Nuclear Resonant Inelastic X--‐ray Scattering and Inelastic Neutron Scattering measurements. The electronic structures and interatomic force constants were calculated with ab--‐initio calculations. The electronic structure is affected strongly by the degree of chemical order in the system. The number of electrons at the Fermi level, which affects the electronic screening, seems to be the most important predictor of the phonon behavior. I will present preliminary results of the calculation of the generalized susceptibility for a few alloys, which is a more sophisticated approach to study the electrons at the Fermi level, although it presents some challenges.
Department Seminar: Friday, March 30:
From Physics and Biology to Engineering and Medicine:
Nanoparticle-augmented ultrasound-guided photoacoustic imaging
Abstract:
A quantitative morphological, functional and molecular imaging technique capable of visualizing biochemical, pharmacological and other processes in vivo and repetitively during various stages of tumor progression and cancer treatment is desired for many fundamental, preclinical and clinical applications. Recently, we introduced several imaging techniques capable of visualizing anatomical structures and functional information about the tissue. Furthermore, targeted contrast agents were developed to enable the cellular and molecular sensitivity of the developed imaging techniques.
In this presentation, combined ultrasound and photoacoustic (USPA) imaging augmented with imaging contrast nanoagent will be introduced with emphasis to principles (physics and biology), approaches (engineering) and applications (medicine). Starting with a brief historical introduction, the foundations of photoacoustics, including derivations and a discussion of governing equations, will be examined. Relevant optical properties of the tissues and the related topics of laser-tissue interaction will be reviewed. The experimental aspects of photoacoustic imaging and sensing will then be discussed with emphasis on system hardware and signal/image processing algorithms. Techniques to increase contrast and to differentiate various tissues in photoacoustic imaging will be presented. The presentation will conclude with an overview of several experimental systems capable of photoacoustic imaging, as well as discussion of current and potential biomedical and clinical applications of photoacoustics.Department Seminar: Friday, March 23:
Dr. Bo Feng
University of Texas at El Paso
Magnetic Moment of Cooper Pairs and Magnetoelectric Effect in Magnetized Color Superconductivity
3:00 pm in PSCI 115Abstract:
In this talk, color superconductivity-the established ground state of nuclear matter at low temperature and extremely high baryon density, will be discussed, especially in the presence of an external strong magnetic field. Specifically, I will consider the color-flavor-locking (CFL) phase of color superconductivity, which is the most favored state at asymptotically high baryon density. Color superconductivity has very unique properties in the presence of a magnetic field, which are quite different from those of conventional superconductivity. The presence of a magnetic field will not only enhance the gap function but also break the rotational symmetry of the system. I will discuss how this symmetry breaking generates new pairing channels in the magnetic CFL phase. One of the resultant new condensates relates to the magnetic moment of the Cooper pairs. The numerical solution shows that this magnetic moment condensate could be of the same magnitude as the other condensates in the strong magnetic field region. The effect of a strong magnetic field on the electric polarization of the magnetic CFL medium will also be discussed. I will show how the electric susceptibility of this strongly magnetized medium becomes highly anisotropic. Along the direction of magnetic field, the electric susceptibility depends on the magnetic field and decreases with it. We attribute the nature of this behavior to the Cooper pairs' electric coherence length, which plays the role of the electric dipole length. The field dependence of the electric polarization is interpreted as the realization of the Magnetoelectric effect in cold-dense quark matter. I will point out how the Magnetoelectric effect for quark matter in a strong magnetic field can become relevant to the phenomenology of compact stars in astrophysics.
Candidate Seminar: Friday, February 24th.
Density Functional Based Methods for Large Scale Calculations on Nanocrystals,Fullerenes, and Organic Photovoltaics
Abstract:
Candidate Seminar: Monday, February 20th.
Quantum Dynamics at the Nanoscale
3:00 pm in PSCI 115Abstract:
Candidate Seminar: Monday, February 6th.
Nematic order and magnetism in the high-temperature iron-based superconductors
3:00 pm in PSCI 115Abstract:
Candidate Seminar: Monday, January 30th.
Abstract:
In this talk, I will give an overview of SERS and focus on the electronic properties underlying this technique. Using first-principles calculations, I will show that SERS provides significantly more spectral information than conventional Raman. I will demonstrate how SERS can probe local chemical interactions of target molecules with metals, unraveling the role of interfacial electron-phonon coupling. The nature of this coupling makes SERS a powerful tool for sensing not only molecules, but also their immediate surroundings, paving the way for molecule-scale discoveries.
First Department Seminar for 2012: Friday January 27
Dilute magnetic oxides and magnetic refrigeration
3:00 pm in PSCI 115Abstract:
Perhaps the most surprising and potentially-significant claim to have been made in magnetism thus far in the 21st century is that nonmagnetic semiconductors and insulators such as ZnO or TiO2 become ferromagnetic at room temperature and above when they are doped with just a few percent of a transition-metal cation such as V, Cr, Mn, Fe, Co or Ni. [Dilute magnetic oxides, J.M.D. Coey, Current Opinion in Solid State and Materials Science 10 (2006) 83–92]. The existence of high-temperature ferromagnetism in thin films and nanoparticles of oxides containing small quantities of magnetic dopants remains controversial. [Ferromagnetism in defect-ridden oxides and related materials, M D Coey, P Stamenov, R D Gunning, M Venkatesan and K Paul, New Journal of Physics 12 (2010) 053025]. In this talk the facts and challenges of diluted magnetic oxides will be exposed, as well as ongoing activities in this topic at CIMAV, S.C.
Magnetic refrigeration is an emerging technology and several issues related with the magnetocaloric material, the structure of magnets and the optimization of parameters of the magnetic refrigerator engineering remain to be resolved. Magnetic refrigeration has four immediate advantages over traditional refrigeration cycles based on compression-evaporation: 1. It is more efficient (15% of energy consumption in the world is due to the use of different types of magnetic refrigeration and magnetic refrigeration has the potential to lower this consumption by 20-30%), 2) No use of harmful gases that affect the ozone layer and cause the greenhouse effect, 3. More compact cooling systems can be built as the working material of the thermodynamic cycle is a solid, 4. Magnetic refrigerators generate much less noise. CIMAV has developed magnetocaloric and barocalóric materials and in collaboration with company iDEA designed and built an experimental prototype of regenerative active magnetic refrigerator.
Last Department Seminar for 2011: Wednesday November 30
The Century of the Nucleus
3:00 pm in Classroom Building C305 (Note room and day change)Abstract:
The atomic nucleus was discovered by Rutherford in 1907 and in the 100 years that followed we have uncovered many –but not all- of the secrets of the nucleus. This talk will provide a chronological review of the major experiments and theories developed to understand the building blocks of all matter in the universe.
Department Seminar for Friday, November 18, 2011
Use of Light in to Manipulate the Structure and Function of Proteins
Abstract:
The functions of proteins depend on their interactions with various ligands and these interactions are controlled by the structure of the polypeptides. If one can manipulate the structure of proteins, there is a chance to modulate their function. The issue of protein structure-function relationship is not only a central problem in Biophysics, but is becoming clear that the ability to “artificially” modify the structure of proteins could be relevant in fields beyond the biomedical area to provide, for instance, light-responses in proteins which would not possess such properties in their native state.
The seminar will present an overview of various methods, the current status of the use of laser-induced conformational changes of proteins and a summary of the findings obtained in our group. Our investigations show that visible irradiation of two porphyrin-type, light-activated drugs with different physico-chemical properties, is capable of prompting unfolding of globular proteins. The unfolding can be as extensive as to involve over 15% of the structure of the polypeptide. Our results show that, contrary to what would be expected for porphyrin-type molecules the photoinduced unfolding is not mediated by the formation of singlet oxygen and in fact does not require the presence of diffusing molecular oxygen at all. This suggest a direct intermolecular charge transfer mechanism from the porphyrin to the protein that prompts this one to change conformation.
Department Seminar for Friday, November 11, 2011
Hunting the Higgs (and Other Animals) at the CERN LHC
3:00 pm in PSCI 115Abstract:
The Higgs Boson is one of the key components of the incredibly successful Standard Model of particle physics. Yet to date the Higgs has not been observed experimentally. In 2011, the Large Hadron Collider (LHC) at CERN delivered impressive amounts of integrated luminosity to the ATLAS and CMS experiments. I will present the current status of Higgs searches carried out by the ATLAS experiment. I'll also discuss other searches for new physics Beyond the Standard Model made possible by the remarkable period of data-taking this year.
Special Department Seminar for Tuesday, November 8, 2011
Critical Issues Facing the Physics Community
Abstract:
Physics and physicists continue to have extraordinary impact on our society and economy. Fundamental discoveries in semiconductors and optics, and increasingly sophisticated tools for modeling complex phenomenon find their ways into many aspects of our lives. Our ability to continue to deliver innovations and discoveries depend fundamentally on the infrastructure of our educational system to prepare the next generation of teachers, physicists, and a scientifically literate population.
I will describe some recent data on how the United States is fairing in this effort. There remains, especially in Texas, a critical shortage of well-qualified high school physics teachers, and a failure to reach several demographics of the population. I will describe some actions that the American Physical Society has taken to address these issues. I invite your questions and look forward to a good discussion on what can be done locally and nationally to improve the situation.
Department Seminar for Friday, October 28, 2011 was cancelled. Rescheduling will be posted.
Dilute Magnetic Oxides
3:00 pm in PSCI 115Abstract:
Department Seminar: Friday, October 21, 2011
From Neutron Stars to Social Dynamics
3:00 pm in PSCI 115Abstract:
Department Seminar: Friday, October 14, 2011
An Introduction to Atmospheric Science and Air Quality Study
3:00 pm in PSCI 115Abstract:
Weather forecasting (meteorology), air quality study, and long-term average weather pattern prediction (climatology) are the major focuses of atmospheric science. The primary methodologies include in situ monitoring or observations; laboratory measurements; and numerical simulation based on the fundamental laws of physics. Air quality study as an important application of atmospheric science provides a valuable planning tool for federal and state environmental protection agencies to form scientific sound policies to improve air quality in polluted areas. An ongoing project with the U.S. EPA to improve the air quality in the New England and Mid-Atlantic region is presented, which features simulations of air pollutant emissions, meteorology, and pollutant concentrations. The talk concludes with an outlook for future air quality study and planning on both the science and policy sides.
Department Seminar: Friday, October 7, 2011
Abstract:
Spectroscopic ellipsometry is an optical technique, which is commonly used to determine the thickness of transparent films in the semiconductor industry and in materials science. But ellipsometry can do much more: The optical properties (complex dielectric function) determined from ellipsometry contain useful information about the electronic, structural, and vibrational properties of materials. I will begin my talk with an introduction of the technique and describe the principles of polarized light, instrumentation for the infrared to vacuum-UV spectral range 135 nm to 30 μm), and how one evaluates the data. Next, I will give examples for different classes of materials: Amorphous and crystalline dielectrics, including high-k metal oxides, semiconductor alloys, and metals. The information derived from ellipsometry is very useful in the discovery of new materials.
Department Seminar: Friday, September 30, 2011
Abstract:
Under high density or high temperature, quarks and gluons will be released from nucleons as it is implied by the asymptotic freedom of QCD. Such a condition may be realized inside a compact star or in the early universe. It can also be implemented via relativistic heavy ion collisions (RHIC). In this talk, the current understanding of the phase structure of a quark-gluon system with respect to temperature and density will be reviewed from QCD first principles or from effective models. The applications of the gauge theory/gravity duality will be discussed.
Department Seminar: Friday, September 16, 2011
Department of Applied Sciences and Mathematics
Arizona State University
Abstract:
The studies of relativistic matter in magnetic fields have seen many breakthroughs over the years. Such studies find applications in several subfields of physics that range in scope from fundamental problems in astrophysics to applied issues in condensed matter physics. In this interdisciplinary talk, I will discuss several qualitative phenomena (including magnetic catalysis, chiral magnetic effect, etc.) in magnetized relativistic matter. I will point out how some of these phenomena can affect the observational features of compact stars and modify the observables in heavy ion collisions. Also, without going into technical details, I will discuss the underlying physics behind the anomalous features of the quantum Hall effect in graphene and how the insights from high-energy physics help to advance the field.
First Department Seminar of 2011-2012!
Abstract
Nanofabrication Facility
In early 2012, UTEP will begin operation of its Nanofabrication Facility. The facility will house class 100 and 1000 cleanroom bays and processing equipment. The $4.5 million, 6876 square-foot facility will be located in a pavilion on the grounds of the Engineering and Science Complex. It will provide a clean environment to the UTEP community critical to nanotechnology research. The facility will also house micro- and nano-electronic processing equipment. For example thin film depositors, dry etchers, oxidation and diffusion furnaces, photolithography apparatus, and electro-optical characterization equipment will be supported. As UTEP strives to become a National Research University, this facility will be a key resource for faculty conducting nanotechnology research. This talk will present details of the facility, research capability of the equipment, and plans for shared use of the capability.
Memristors and Resistive Switching
The semiconductor industry is a leader of advanced high-technology manufacturing, producing trillions of devices annually with unprecedented nanometric scale precision (~3 nm vertically and 30 nm laterally – 22 atoms vertically and 220 atoms laterally) for electronic applications ranging from wireless communications, to computers, to consumer electronics with ever increasing levels of sophistication and functionality. The building block of integrated electronic circuits is the transistor. However, continued miniaturization will cause Moore’s Law to reach the end of the road in the year 2020 according to the Semiconductor Industry Association’s technology road map. This has created much interest in creating new devices to replace the transistor. One recent invention is the memristor, which has great potential due to its simple structure and concomitant ease of fabrication, increased packing density due to its small size and amenability for complex nonlinear functionality. It is a two-terminal, passive device in the same category as resistors, inductors and capacitors. The memristor has potential to increase the functionality of integrated electronics well beyond 2020. However, much research is needed to understand the operating mechanisms and optimize the device. This presentation reviews memristors and resistive switching and highlights research on SnO2-based memristors at UTEP.
CdTe Thin-Film Solar Cells
Last year, CdTe thin-film solar modules broke the manufacturing cost barrier of $1/Watt using economy of scale. However, due to persistently low module efficiency of ~10%, the cost of photovoltaic (PV) power is still 2 to 4 times the cost of power from the grid. High solar conversion efficiency in CdTe modules is a key to reducing total PV system costs to grid parity. CdTe has an ideal direct bandgap of 1.5 eV providing a theoretical conversion efficiency of ~30%. However, laboratory CdTe cell performance has remained stagnant for the last 17 years at 16%. The challenge is high defect density generated due to the lattice mismatch between CdS and CdTe. These defects trap carriers and in turn reduce the current, voltage, and efficiency of the device. This talk presents collaborative research between Sandia National Labs and UTEP on CdTe-based solar cells using nanotechnology.