Colloquia

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Friday, February 1, 2019

Time: 12 pm - 1:30 pm

Location: BLHSB 1.104 (Brownsville), EACSB 1.104 (Edinburg)

Noise reveals unusual pairs in cuprate superconductors

Superconductivity is the flow of electrical current with no resistance, thanks to the pairing up of charge carriers and their coherence in a single quantum state.  In the 1980s, a family of copper oxide materials were discovered that show superconductivity at comparatively high temperatures, and after 30 years of study, we still don't have a good understanding of these compounds, including their properties in the "normal" state at temperatures above the superconducting transition,  T _c .  Other effects are also seen (the "pseudogap"; spatial patterns of charge) in the normal and superconducting states.  Two big questions have been, "Do the carriers actually pair up at even higher temperatures, and only start to superconduct at the transition?", and "What is the relationship between superconductivity and other kinds of electronic states?" Working with atomically precise materials, we have measured quantum tunneling of charge from one copper oxide superconductor to another, through a copper oxide insulating barrier.  From the fluctuations in the tunneling current ("shot noise"), we have shown directly that there are pairs above  T _c , and that these pairs survive out to energy scales much larger than superconductivity.  I will discuss what these measurements imply for the answer to those open questions.

Speaker:  Dr. Douglas Natelson (Rice University, the Department of Physics and Astronomy)

About the speaker: Prof. Natelson earned a BSE in Mech. and Aerospace Engineering at Princeton and a PhD in physics at Stanford, followed by a postdoctoral stint at Bell Labs before coming to Rice University in 2000. His research program uses nanoscale structures as tools to address open questions in condensed matter physics. Prof. Natelson is particularly interested in the electronic, optical, and magnetic properties of systems with strong electronic correlations and/or driven out of equilibrium, and always keeps one eye on possible technological applications. He is a fellow of the APS and AAAS, and is currently chair of Rice’s Department of Physics and Astronomy. Prof. Natelson is passionate about the importance of communicating science to the public, and has maintained a blog about nano and condensed matter (nanoscale.blogspot.com) since 2005 to further this goal. He has also written a senior-level textbook, Nanostructures and Nanotechnology, published in 2015 by Cambridge University Press (amazon.com/Nanostructures-Nanotechnology-Douglas-Natelson/dp/0521877008/).

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Friday, February 8, 2019

Time: 12 pm - 1:30 pm

Location: EACSB 1.104 (Edinburg), BLHSB 1.104 (Brownsville)

Peakon, cuspon, and short pulse models generated through the negative-order integrable systems

In my talk, I will introduce integrable peakon and cuspon equations and present a basic approach to get peakon solutions. Those equations include the well-known Camassa-Holm (CH), the Degasperis-Procesi (DP), and other new peakon equations. I take the CH case as a typical example to explain the details. My presentation is based on my previous work (Communications in Mathematical Physics 239, 309-341). I will show that the Camassa-Holm (CH) spectral problem yields two different integrable hierarchies of nonlinear evolution equations (NLEEs), one is of negative order CH hierarchy while the other one is of positive order CH hierarchy. The two CH hierarchies possess the zero curvature representations through solving a key matrix equation. We see that the well-known CH equation is included in the negative order CH hierarchy while the Dym type equation is included in the positive order CH hierarchy. Also, in this talk, we will see those physical models: short pulse (SP), complex short pulse (CSP), two-component SP (2SP), and two-component CSP (2CSP) equations were derived from the negative AKNS flows (see JMP 44(2003), 701-722 for details), and Lax pair for those models and the entire hierarchy was explicitly provided as well. Some open problems are also addressed for discussion.

Speaker:  Dr. Zhijun Qiao (UTRGV, Math)

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Friday, February 15, 2019

Time: 12 pm - 1:30 pm

Location: EACSB 1.104 (Edinburg), BLHSB 1.104 (Brownsville)

Electron Density Topological Analysis and its applications on adsorption

The quantum theory of atoms in molecules (QTAIM), developed by Bader and co- workers, teaches that wavefunctions and orbitals are unphysical in nature and thus, not observed experimentally. However, the election density and its derivatives are observables (i.e., current density and election density Laplacian) and can be used to describe chemical bonding. Calculated QTAIM properties are method and basis-set independent. In QTAIM, the electron density contains all information needed to describe a chemical system. For example, nuclei locations correspond to electron density maxima, whereas bonds critical points to saddle points in the density. Additionally, the election density Laplacian provides a shell-type spherical structure in alternating shells of charge concentration and depletion: It is used to identify donor-acceptor interactions. We use QTAIM to analyze CO adsorption on hydrated and dry Pt surfaces and examine Li and Na adsorptions on graphene and graphene oxides. Specifically, the electron density Hessian eigenvalues are correlated with changes in the σ and π C-O bonding for various CO coverages and hydrations. The Li and Na adsorptions on graphene and graphene oxides (GO) electronic and structural properties are correlated with changes in the metal-C bond critical points for adsorption on various supports (i.e., pristine and defective graphene and GO) at various metal coverages. QTAIM reveals that Li forms a partially covalent bond with graphene carbon, when Li is adsorbed on single vacancy graphene. The above adsorptions are also analyzed using the changes in the electron localization function (ELF) via the development of bifurcation diagrams.

Speaker:  Dr. Nicholas Dimakis (UTRGV, Physics)

About the speaker: Professor Nikolaos (Nicholas) Dimakis graduated with a BS degree from the National University of Athens in Mathematics in 1990. He obtained his MS in Applied Optics with Distinctions from the University of Salford, UK on 1992 and his PhD. in Physics on 1997 from the Illinois Institute of Technology (IIT), Chicago. His Ph.D. thesis with Prof. Grant Bunker was on calculating the thermal multiple-scattering XAFS Debye-Waller factors. He was employed as Senior Research Associate at Argonne National Laboratory and Associate Director of Science of the Academic Research Center at IIT. In 1999 he became Assistant Research Professor at IIT. He joined the University of Texas-Pan American during the fall of 2004 as Assistant Professor in the Department of Physics and Geology. He became Associate Professor at 2010 and later served as Interim and Department Chair. Currently he is a UTRGV Professor of Physics.

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Friday, February 22, 2019

Time: 12 pm - 1:30 pm

Location: BLHSB 1.104 (Brownsville), EACSB 1.104 (Edinburg)

Detection of Gravitational Waves from Core Collapse Supernovae

Core collapse supernovae (CCSN) in our universe are potential sources of gravitational waves (GW) that could be detected in a network of GW detectors. CCSN rates are low, but the associated GW is likely to carry profuse information about the underlying processes leading to the collapse. Calculations based on analytic models predict GW energies within the detection range of the Advanced LIGO detectors, out to tens of Mpc for coalescing binary neutron stars. But for supernovae, the distances are much less. Improvements in the sensitivity of searches for GW signals from CCSN are highly desirable. Several methods have been proposed based on various likelihood-based regulators that work on data from a network of detectors We have developed an analysis pipeline based on a new way to effectively enhance the signal to noise ratio leading to a higher efficiency detection and increase of the detection range. Results using real LIGO noise and some of the current CCSN explosion models will be discussed. 

Speaker:  Dr. Soma Mukherjee (UTRGV, Physics and Astronomy)

About the speaker: Dr. Soma Mukherjee is a Professor and the Chair of the Physics and Astronomy department at the University of Texas Rio Grande Valley (UTRGV). She obtained Ph.D in Physics from the University of Calcutta, and did post-doctoral studies at LIGO-Caltech, Pennsylvania State University and Max Planck Institute of Gravitational Physik where she was a first a post-doctoral scholar and then a faculty-equivalent scientist. She joined the University of Texas Brownsville in 2003 Fall and the UTRGV in 2015. She is a member of the LIGO Scientific Collaboration (LSC) since its inception in 1997. More recently, she is a co-author (with the LSC) on the Gravitational Wave (GW) discovery paper in Phys Rev Lett in 2016 and a winner (as an LSC member) of the Breakthrough Prize in Fundamental Physics, Gruber Cosmology Prize and other recognitions for her contribution to the LSC GW research. She has co-authored over 200 publications, been a PI, co-PI and senior investigator on numerous NSF and NASA grants, delivered innumerable invited talks across the world and mentored many undergraduate and graduate students.

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Friday, March 1, 2019

Time: 12 pm - 1:30 pm

Location: EACSB 1.104 (Edinburg), BLHSB 1.104 (Brownsville)

Science and Technology of Graphene-family Nanomaterials: Opportunities at the Grand Challenges of  Energy-Water-Sensing  Nexus

Graphene, an atomic thin sheet of sp ²-hybridized carbon atoms joined covalently to form a two-dimensional (2D) hexagonal honeycomb lattice, has stimulated extensive research and development interests since its inception due to extraordinary physical-chemical-biological properties. Likewise, graphene-family nanomaterials (GFNs) including graphene oxide (GO), reduced GO (rGO), doped (nitrogen, boron and sulfur) graphene nanosheets and nano/macroporous graphene are equally emerging candidates for a range of technologies, especially at the grand challenges of renewable energy, water detoxification and sensing applications.      In this talk, I will present ongoing research in my group related to graphene-based hybrids and aerogels and their widespread attention as potential game changer materials, accelerated by combining them with other nanomaterials such as transition metal oxides, conducting polymers, noble metal nanoparticles and carbon nanotubes. In the first part, I will discuss novel synthetic approaches for strategic material design targeting specific application, examples include: a) chemical and molecularly bridged graphene/metal oxides via electrodeposition; b) shear-aligned graphene oxide large-area membranes; and c) integrating carbon nanotubes as ‘nano’ spacers with graphene for increasing surface area for electrosorption and as ‘organic’ thermo-electrochemical energy harvesters [1-5]. For the second part of my talk, advanced characterization gaining fundamental insights into the mechanisms related to electrochemical energy storage, water desalination or sensing highlighting the interfacial properties will be presented [1-5]. The scanning electrochemical microscopy (SECM) is a powerful analytical tool to investigate dynamic physical-chemical processes occurring at surfaces and buried interfaces. This technique helps to determine heterogeneous electron transfer kinetic rate, diffusion coefficient, monitor electrochemical redox reactions as well as image highly electroactivity sites. These findings supplemented by theoretical calculations, reinforce the available electron density of states for the systems studied in the vicinity of the Fermi level contributing to higher electroactivity are emphasized [1-3, 6]. Finally, this research work opens up new innovations for graphene-based and graphene-related 2D systems as quantum materials with significant value propositions for academicians and industrials alike.[1] Gupta et al., Appl. Phys. Lett.  109, 243903 (2016).
[2] Gupta  et al., J. Appl. Phys.  124, 124304 (2018)
[3] Gupta  et al., J. Mater. Res.  32, 301 (2017).
[4] Gupta  et al., Sensors & Actuators B  274, 85 (2018).
[5] Gupta et al.,  submitted (2019).
[6] Gupta et al., Appl. Surf. Sci.  465, 760 (2019).

Speaker:  Dr. Sanju Gupta (Western Kentucky University, Physics and Astronomy, Advanced Materials Institute)

About the speaker: Dr. Gupta joined WKU Physics department and Astronomy as an associate professor in fall 2013. She received her BS (Hons.) in from Delhi University (DU), New Delhi-India, MS degree with Solid-State Physics specialization from prestigious Indian Institute of Technology-Delhi (IITD), MTech in Laser Technology from Indian Institute of Technology-Kanpur (IITK). She moved to University of Puerto Rico-Rio Piedras Campus and Institute of Functional Materials on NSF and DoE Graduate student Research Fellowships and received her PhD in Chemical Physics under the supervision of Profs. Brad Weiner and Gerardo Morell. After completing her PhD in 2002, she went to University of Cambridge in United Kingdom Department of Engineering joining Electronic Materials and Device (EMD) group where she worked as a postdoctoral research associate with Prof John Robertson. After Cambridge University, she accepted a research scholar position at North Carolina State University-Raleigh Physics Department to work with Prof Robert Nemanich (now at Arizona State University). After that she moved to Missouri State University and University of Missouri-Columbia as assistant professor in the Physics, Astronomy and Materials Science and Electrical Engineering Department, respectively. While she worked for more than a decade in the area of frontier nanocarbon material thin films for a range of electronic, microelectronics and electromechanical device applications, she was seeking new inspirations and motivation. She arrived at the University of Pennsylvania-Philadelphia on NIH fellowship where she worked on experimental protein biophysics using x-ray and neutron scattering techniques besides teaching at Drexel University, Philadelphia in Physics and Astronomy Department as an adjunct faculty. She is a recipient of several awards throughout her career since her undergraduate and three patents including for her PhD studies. She has also been a visiting scholar at the Politecnico di Torino, Italy, University of Texas-Nano Tech Institute-Dallas and Los Alamos National Laboratory in 2009, 2008 and 2004, respectively. She has multidisciplinary collaborators due to the nature of her research spanning electrical, mechanical, biomedical, and materials science engineering, chemistry and theoretical physics. She has taught in Physics, Materials Science and Electrical Engineering departments at various places and both undergraduate and graduate levels throughout USA since 2004.

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Friday, March 8, 2019

Time: 12 pm - 1:30 pm

Location: BLHSB 1.104 (Brownsville), EACSB 1.104 (Edinburg)

The future of the Universe:
Will we ever have a theory of everything?

In this colloquium I will discuss, at a non-technical level, several conundrums we face in our understanding of the universe. I will describe the crisis of the standard model of particle physics, the quandaries presented by the search for dark matter and the characterization of what we call dark energy. I will discuss how could they be related to finding a quantum theory of gravity. I will compare them with the various attempts through history to have a unified view of the physical phenomena in our universe. I will finally reflect on the possible solution to some of them from the optimistic perspective of a gravitational wave Astronomer.

Speaker:  Dr. Mario Diaz (UTRGV, Physics and Astronomy, Center for Gravitation Wave Astronomy)

About the speaker: Dr. Mario Diaz is a Professor in the Department of Physics and Astronomy and the Director of the Center for Gravitational Wave Astronomy at the University of Texas Rio Grande Valley (UTRGV). Dr. Diaz obtained his Ph.D. in Physics from the Universidad Nacional de Cordoba in 1987, and did post-doctoral studies at the University of Pittsburgh from 1988 to 1990. He joined the University of Texas Brownsville in 1996 and was appointed Professor in 2003. Dr. Diaz is the PI of the UTRGV LIGO Scientific Collaboration (LSC) group and an LSC Council member since 2003. He was the Chair of the Texas section of the American Physical Society in 2012. He has received more than $30M in grants from several government funding agencies including NSF, NASA, and AFOSR. He was a Distinguished Fulbright Chair in Gravitational Wave Detection at the University Federico II in Naples, Italy in 2004. He has received the Gruber Prize in Cosmology from Yale University with the LSC in 2016, the Special Breakthrough Prize in Fundamental Physics with the LSC in 2016, the Princess of Asturias Prize (Spanish Crown) with the LSC in 2017, and the Bruno Rossi Prize of the American Astronomical Society with LSC in 2017 all of which are for the discovery of gravitational waves.

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Friday, March 22, 2019

Time: 12 pm - 1:30 pm

Location: EACSB 1.104 (Edinburg), BLHSB 1.104 (Brownsville)

Single-molecule studies of how MORC protein functions and condenses DNA

Microrchidia (MORC) proteins are a highly conserved family of GHKL (Gyrase, HSP90, Histidine Kinase, MutL) ATPases that are critical for gene silencing and chromatin compaction in both plants and animals. However, the functional mechanism by which MORCs act is poorly understood. Here we show that C. elegans MORC-1 protein binds to DNA in a length-dependent yet non-sequence specific manner. To further elucidate mechanisms of MORC function, various single-molecule techniques were employed. First, our single-molecule flow-stretching experiments show that it can robustly compact naked DNA in a mildly ATP-dependent manner. After initial binding to DNA, MORC-1 forms multimeric assemblies that grow as DNA compaction proceeds, which is consistent with our observations that MORC-1 forms discrete nuclear puncta in C. elegans. Another single-molecule technique called DNA motion-capture assay based on the laminar flow nature of our microfluidic flowcell indicates that this DNA condensation activity appears to act via a loop trapping mechanism. Furthermore, the multimeric assemblies do not leave the flow-stretched DNA upon high salt wash when the free end of the DNA is tagged with a bulky quantum dot, which suggests that they topologically entrap the DNA. These results highlight several aspects of MORC-1 complex assembly on DNA that are relevant to understanding the fundamental mechanism of MORC action in a variety of organisms.

Speaker:  Dr. HyeongJun Kim (UTRGV, Physics and Astronomy)

About the speaker: Dr. HyeongJun Kim is a single-molecule biophysicist by training and currently an Assistant Professor in the Department of Physics and Astronomy at the University of Texas Rio Grande Valley (UTRGV). He obtained a BS degree with honor in physics from Yonsei University in Seoul, Korea and worked in a semiconductor LED wafer company as a part of obligatory national service. Intrigued by interdisciplinary subjects, he moved to the US in 2005 and joined a single-molecule biophysics laboratory led by Dr. Paul R. Selvin at the University of Illinois at Urbana-Champaign (UIUC). He obtained MS and Ph.D. degrees in Physics in 2009 and 2011, respectively. Before joining UTRGV, Dr. Kim was a postdoctoral researcher at the Department of Biological Chemistry and Molecular Pharmacology in Harvard Medical School where he continued his single-molecule researches and acquired various molecular biology and biochemistry techniques.

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Friday, April 5, 2019

Time: 12 pm - 1:30 pm

Location: BLHSB 1.312 (Brownsville), EENGR 1.262 (Edinburg)

Mining Metastable Phase Space for New Function: Some Perspectives for the Design of Cathode Materials and Logic Circuitry

The known crystal structures of solids often correspond to the most thermodynamically stable arrangement of atoms. Yet, oftentimes there exist a richly diverse set of alternative structural arrangements that lie at only slightly higher energies and can be stabilized under specific constraints (temperature, pressure, alloying, point defects). Such metastable phase space holds opportunities for non-equilibrium structural motifs and distinctive chemical bonding and ultimately for the realization of novel function. I will discuss the challenges with the prediction, stabilization, and utilization of metastable polymorphs. Using two canonical early transition-metal oxides, HfO ₂ and V ₂O ₅, as illustrative examples where emerging synthetic strategies have unveiled novel polymorphs, I will highlight the tunability of electronic structure, the potential richness of energy landscapes, and the implications for functional properties.  In recent work, we have explored the intriguing electronic phase diagrams of low-dimensional ternary vanadium oxides with the formula M _x V ₂O ₅ where M is an intercalating cation and  x is its stoichiometry. Several of these compounds show colossal metal—insulator transitions and charge ordering phenomena. The talk will focus on mechanistic understanding of these transitions and their implications for the design of new “brain-like” vectors for computing. If  composition does not have to be structural destiny, a powerful new palette becomes available for tuning material properties. I will demonstrate the application of this M _x V ₂O ₅ palette to two specific problems: (a) the design of cathode materials for multivalent insertion batteries; and (b) the design of photocatalysts for the water oxidation reaction.  Schematic illustration of the energy landscape of HfO ₂

Speaker:  Dr. Sarbajit Banerjee (Texas A&M University, College Station)

About the speaker: Sarbajit Banerjee is the Davidson Professor of Chemistry and a Professor of Materials Science & Engineering at Texas A&M University. Sarbajit is a graduate of St. Stephen’s College (B.Sc.) and the State University of New York at Stony Brook (Ph.D.). He was a post-doctoral research scientist at the Department of Applied Physics and Applied Mathematics at Columbia University prior to starting his independent career at the University at Buffalo in 2007. He moved to Texas A&M University in 2014. He was awarded a National Science Foundation CAREER award in 2009; the American Chemical Society ExxonMobil Solid-State-Chemistry Fellowship in 2010; the Cottrell Scholar Award in 2011; the Minerals, Metals, and Materials Society Young Leader Award in 2013; the American Chemical Society Journal of Physical Chemistry Lectureship in 2013; the Scialog Innovation Fellowship in 2013; the IOM3 Rosenhain Medal and Prize in 2015; and the Royal Society of Chemistry/IOM3 Beilby Medal in 2016. He is a Fellow of the Royal Society of Chemistry and the Institute of Physics. In 2012, MIT Technology Review named Sarbajit to its global list of “Top 35 innovators under the age of 35” for the discovery of dynamically switchable smart window technologies that promise a dramatic reduction in the energy footprint of buildings. His research interests are focused on solid-state chemistry, electron correlated materials, mechanisms of electrochemical energy storage, heavy oil processing, and functional coatings.

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Friday, April 12, 2019

Time: 12 pm - 1:30 pm

Location: BLHSB 1.104 (Brownsville), EENGR 1.262 (Edinburg)

How to publish in Physical Review Letters

Publication is an essential part of scholarly research and integral to most scientists' careers. A good understanding of the authoring and reviewing processes helps authors navigate their way to a published manuscript. In this colloquium, editor from Physical Review Letters and will give an overview of the policies and procedures, and an update on publishing news from Physical Review journals.

Speaker:  Dr. Stojan Rebic (Physical Review Letters, Associate Editor)

About the speaker: After growing up in Croatia, Stojan completed his graduate studies at the University of Auckland, New Zealand, with a thesis on theoretical quantum optics. He was postdoctoral fellow at the University of Camerino, Italy. Afterwards he held a position of Visiting Associate Professor at Macquarie University, Sydney and Australian National University, Canberra in Australia. He joined Physical Review Letters. His research interests are in theoretical quantum optics, in particular cavity QED, interaction of light with atomic ensembles and understanding of realistic quantum optical systems for application in quantum technologies.

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Friday, April 18, 2019

Time: 12 pm - 1:30 pm

Location: BSABH 2.110 (Brownsville), ELABS 185 (Edinburg)

News from the NSF

I will discuss the current status of the NSF and talk about various funding opportunities in Physics and Astronomy.

Speaker:  Dr. Matthew Benacquista (UTRGV, Physics & Astronomy, NSF)

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Friday, April 26, 2019

Time: 12 pm - 1:30 pm

Location:EACSB 1.104 (Edinburg), BLHSB 1.104 (Brownsville)

Harnessing the intermolecular Coulombic decay mechanism for targeted energy transfer in solution

Intermolecular Coulombic decay (ICD) is a well-established mechanism for energy transfer between core-excited atoms and their neighbors. Some years ago, my collaborators and I used plane-wave density functional theory (pwDFT) and a simple density-of-states (DOS) comparison to explain ICD-related features in the x-ray photoelectron spectrum of aqueous NaOH. Here I present extensions of this qualitative approach for predicting ICD that depend only on information easily obtained by molecular dynamics simulation and pwDFT. Specifically, we develop energetic criteria based on excess overlap between chemically distinct contributions to the total DOS, as well as complementary spatial criteria based on the radial distribution function. We use these measures to predict the preferred target for ICD from core-excited bismuth(III) in an aqueous solution containing citrate anions and 1,4-dioxane. Synchrotron experiments demonstrate not only that citrate is the target, as predicted, but that there is a fivefold enhancement in the citrate:dioxane destruction ratio over background radiolysis (i.e., in the absence of bismuth) that drops off as bismuth precipitates from the solution. I will discuss how our criteria can be used to screen for ICD propensity and how to estimate near-field effects in the corresponding measurements using analytic calculations of solid angles. Throughout, I will emphasize that these insights may contribute to the development of new coadjuvant therapies for use in cancer radiotherapy. Time allowing, I will summarize other current research and opportunities in my group for students in the Department of Physics and Astronomy.

Speaker:  Dr. Shervin Fatehi (UTRGV, Chemistry)

About the speaker: Shervin Fatehi earned an S.B. in chemistry from MIT in 2004. He spent a year studying the statistical mechanics of liquids with David Chandler at UC Berkeley before changing focus to approximate quantum dynamics methods and theoretical X-ray spectroscopy, completing a Ph.D under the supervision of William H. Miller and Richard J. Saykally in 2010. During consecutive postdoctoral appointments (2011–2015) with Joseph E. Subotnik (University of Pennsylvania) and Ryan P. Steele (University of Utah), he developed expertise in nonadia- batic phenomena, analytic gradient theory, and ab initio molecular dynamics. In Fall 2015, Dr. Fatehi joined the founding faculty of UTRGV as a member of the Department of Chemistry. His current research focuses on the development of theoretical and computational methods that deepen our understanding of the interplay between the electronic structure of molecules (quantum chemistry), their motions and rearrangements (chemical dynamics), and their inter- actions with light (spectroscopy). Projects include exploring the importance of nonadiabatic effects in mechanochemistry and the application of stochastic electronic structure methods to simulating molecular motion; the latter work is funded by the Welch Foundation.

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Advanced LIGO’s third observing run has begun

 

Advanced LIGO’s third observing run has started on April 1 after a series of upgrades that increased its sensitivity by 40%. The talk will report on the improvements that went into the detectors and will show results and observations that have been made so far by previous observing runs.

 

 

Speaker:  Dr. Volker Quetschke (UTRGV, Physics and Astronomy)

 

     

About the speaker: Dr. Volker Quetschke is an Associate Professor in Department of Physics and Astronomy at UTRGV. He joined UTB/UTRGV in 2009 and while he maintains a strong research agenda in experimental gravitational wave detector physics, he has been extremely active in service and leadership activities. He shows great dedication to help the profession, the department, the college, and the university in general. He believes improving the university makes it a better place for students and faculty while student success and research are strengthened. He earned his doctoral degree in 2003 at the Leibniz University in Hannover, Germany working on identifying and reducing the noise of laser systems for gravitational wave detectors.  He joined the University of Florida in 2003 and became first a post-doctoral researcher and later a Research Assistant Professor. Dr. Quetschke’s research mainly focusses on the Laser Interferometer Gravitational-Wave Observatory (LIGO) where he is involved in improving the laser and input optics as well as designing the next generation detector. He chairs the Lasers and Auxiliary Optics working group of the LIGO Scientific Collaboration (LSC) and is a council member of the LSC. The LSC consists of more than 1000 scientists from over 100 institutions and 18 countries worldwide. Dr. Quetschke holds two patents and has published more than 200 peer reviewed articles.

His scholarly activities already reflect his involvement in service and leadership for the academy, but in addition to that he serves as the Associate Chair of the Department of Physics & Astronomy at UTRGV and in several committees. Dr. Quetschke leads the Arecibo Remote Command Center (ARCC) of the Center for Advanced Radio Astronomy (CARA). ARCC is a unique program that provides a cohort-based education to undergraduate students, while exposing them early to research projects. He is representing the interests of the faculty as a member of the Faculty Senate at UTRGV and currently serves as the President of the Senate. Statewide he is representing the faculty as Co-chair for Academic Affairs and Faculty Quality of the University of Texas System Faculty Advisory Council (FAC).

Dr. Quetschke is a co-recipient of the Breakthrough Prize 2016 for detection of Gravitational Waves 100 Years after Albert Einstein predicted their existence and a co-recipient of the 2016 Gruber Cosmology Prize for pursuing a vision to observe the universe in gravitational waves, leading to a first detection that emanated from the collision of two black holes.

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Size- and Shape- Controlled Properties of Nanostructured Systems

 

In the last decade there has been a significant progress in condensed matter physics at the nanoscopic level with development of several new concepts that provided variety applications on the size and shape dependent phenomena. This talk will summarize our current progress towards developing a framework of principles for design and fabrication of nano tailored structures to use in highly dense energetic systems, environmental protection and biomedical applications. I will present novel metastable intermolecular composites that enable a more concentrated energy release and potentially can be used in military, space and bio defeat applications. The novel patented cost-effective and energy efficient synthesis of nanostructured complex oxides and fabrication of various devices/systems such as hard and soft magnetic materials, superconductors, multiferroics, environmental photocatalysts, MRI contrast agents for cancer localization and hyperthermia treatment will be presented. Key factors that affected to the device characteristics (magnetization, conductivity, capacity, relaxation time, and others) will be discussed in details. Development of these emerging technologies warrants a multifaceted approach, which includes interdisciplinary collaboration, partnerships and integration of modern problems into materials physics curriculum.

 

Speaker: Dr. Karen Martirosyan (UTRGV, Physics and Astronomy)

 

 

  

 

About the speaker: Dr. Martirosyan’s research interests are focusing on the design and fabrication of a novel advanced multifunctional nano-tailored devices and systems for energy, environmental and biomedical applications. The research area covers a broad spectrum of advanced materials, their design, fabrication, characterization and solid-state phenomena. He has been the principal investigator and co-investigator for numerous Federal and State funded research projects. His work has resulted in more than 130+ refereed journal papers, 20 patents and over 150 presentations at national and international conferences. He was three-time recipient of the AFRL summer fellowship program at Eglin Air Force Base, Florida.

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Swarm intelligence in Gravitational Wave data analysis

As in many other fields of science dominated by Big Data problems, the success of gravitational wave Astronomy depends critically on solving outstanding and difficult data analysis challenges. Many of these challenges are rooted in the difficulty of numerically optimizing functions that are high-dimensional and multi-modal. At UTRGV, we have pioneered the use of cutting-edge stochastic optimization methods from the field of swarm intelligence to address some of these problems. In this talk, we will review the work that has been done in this area at UTRGV and the successes we have had. These successes in turn point the way to new and interesting data analysis challenges, not limited to gravitational wave data analysis alone, that are ripe for solution using swarm intelligence methods.

 

Speaker: Dr. Soumya Mohanty (UTRGV, Physics and Astronomy)

 

TOROS, the present and the future

A project status report

In this talk I review the status of the TOROS project, which seeks to install, commission and operate a wide field of view optical telescope in the highlands of the Atacama dessert.

The main goal of the project is to follow-up and characterize gravitational wave transients in the electromagnetic spectrum. I will also discuss the current LIGO VIRGO observational campaign, its provisional preliminary results and the prospects for the new ones after 2020.

Speaker: Dr. Mario Diaz (UTRGV, Physics and Astronomy)

Searching for the Inner Phase of Neutron Stars

 

Compact stars with significant high densities in their interiors can give rise to quark deconfined phases that can open a window for the study of strongly interacting dense nuclear matter. Recent observations on the mass of two pulsars, PSR J1614-2230 and PSR J0348+0432, have posed a great restriction on their composition, since their equations of state must be hard enough to support masses of about at least two solar masses. On the other hand, from spectroscopic and spin-down studies of soft-γ-ray repeaters (SGRs) and anomalous x-ray pulsars (AXPs), it has been inferred that surface magnetic fields of order 10 ¹⁴−10 ¹⁵G occur in some special compact objects called magnetars. Moreover, the inner core magnetic fields of magnetars can be even larger, as follows from the magnetic field flux conservation in stellar media with very large electric conductivities. The inner fields have been estimated to range from 10 ¹⁸G for nuclear-matter stars to 10 ²⁰G for quark-matter stars.

 

The onset of quarks tends to soften the equation of state, but due to their strong interactions, different phases can be realized with new parameters that affect the corresponding equations of state and ultimately the mass-radius relationships. In this talk I will review how the equation of state of dense quark matter is affected by the physical characteristics of the phases that can take place at different baryonic densities, as well as in the presence of strong magnetic fields.

 

Speaker: Dr. Efrain J. Ferrer (UTRGV, Physics and Astronomy)

 

PHYSICAL ASPECTS IN POLYMER-BASED NANOCOMPOSITES

 

     The seminar will focus on one of my most important research directions in nanomaterials, namely the physical properties of polymer-based nanocomposites. Polymer-based nanocomposites is a class of materials that typically involves polymeric matrices loaded by various nanoparticles. Frequently this definition is extended to include polymer blend, when the physical features of at least one component is controlled by submicron confinement or interfaces as well as classical composite materials, with a micron filler or larger if the surface is very thin (usually below 100 nm) and some physical properties are controlled by the interface.

 

     The nanofiller adds new physical properties to the polymer-based nanocomposites such as electrical conductivity, magnetic characteristics, dielectric features. The huge possibilities to modify the physical properties of the polymeric matrix by adding such nanoparticles open the door to new materials, with advanced properties, and eventually multifunctional properties. The methods to obtain such nanocomposites are typically easy scaled up to industrial scale, explaining thus the huge interest of the industry.

 

     My research in the last years was concentrated on the following directions:

 

1. The polymer-nanofiller interface and the transition from the bulk to the surface properties in polymer-based nanocomposites.
2. Phase transitions (glass, melting, and crystallization) and molecular dynamics in polymer based nanocomposites
3. Polymer nanofibers and their nanocomposites
4. Molecular basis of the elasticity of polymeric materials and polymer-based nanocomposites, as revealed by vibrational spectroscopy (Raman and FTIR).

 

The colloquium will briefly discuss all these directions, while focusing on recent data in the study of the molecular basis of elasticity in polymer-based nanocomposites by Raman spectroscopy.

Speaker: Dr. Mircea Chipara (UTRGV, Physics and Astronomy)

 

Friday, October 25, 2019

Physical mechanisms of cell nuclear mechanics and structure

The cell nucleus is often referred to as the control center of the cell because it houses the genome, which encodes cellular function. However, the nucleus is also a mechanically responsive object that actively organizes and physically protects the >1-meter-long chromatin polymer (DNA and proteins) contained within. To understand the physical mechanisms of these phenomena, I use simulation and theory to explore: 1) how two major nuclear components govern mechanical response and 2) how mesoscale chromosome folding is driven by molecular motors. First, I show that chromatin has an essential role in maintaining nuclear structure. Nuclear mechanical response is well described by a model of a chromatin polymer gel enclosed by a polymeric lamin shell. This model predicts an experimentally observable, strain-stiffening mechanical response. These mechanics lead to a buckling transition and regulate nuclear shape abnormalities found in human diseases, such as progeria and breast cancer. Second, I develop a theory for “loop-extruding” condensin protein complexes, which linearly compact chromosomes 1000-fold by reeling in DNA and extruding it as loops. While a form of this novel motor activity has been observed in recent in vitro single-molecule experiments, my theory predicts that the microscopic observations cannot fully explain in vivo human chromosome compaction. However, the model suggests how condensins may nonetheless achieve such dramatic compaction in vivo. Together, the models and corresponding experiments demonstrate how biologically essential cell-nuclear properties emerge from the mechanical response and nonequilibrium activities of chromatin.

 Speaker: Dr. Edward J. Banigan (MIT, Physics, Institute for Medical Engineering and Science)

 

Friday, November 8, 2019

Globular clusters

 

Globular star clusters are densely packed spherical agglomerations of stars. These stellar systems are found orbiting our own galaxy, the Milky Way and all kinds of galaxies across the Universe. Globular clusters feature prominently in different aspects of astrophysical research, for example they provide an accurate measurement of the age of the Universe. Globular clusters are also used to trace the dynamical evolution of galaxies, and galaxy clusters. The internal dynamics of globular clusters can be studied with N-body simulations. These dynamical simulations tell us how the hundreds of thousands of stars that form a globular cluster interact with one another. As one of the densest stellar structures in the Universe stellar collisions are known to frequently occur within globular clusters, among them the binary systems that are responsible for gravitational waves.

 

Speaker: Dr. Juan Madrid (UTRGV, Physics and Astronomy)

Friday, November 15, 2019

(Talk 1) Optical Configurations of Laser Gravitational Wave Detectors  

Speaker: Mr. Anton Gribovskiy (UTRGV, Physics and Astronomy, 6 ^th year PhD student)

(Talk 2) Improving Models of Thermal Atmospheric Newtonian Noise for Advanced and 3 ^rd Generation Gravitational-Wave Detectors

Speaker: Ms. Wenhui Wang (UTRGV, Physics and Astronomy, 5 ^th year PhD student)