Second Nuclear and Particle Theory Meeting

The objective of this second meeting is to discuss and exchange ideas on recent research topics in nuclear and particle physics, with the special focus on dense matter in neutron stars and binary neutron star mergers. This small and informal meeting is meant to bring together the dense matter and neutron star theory community and experts of adjacent fields with the scope of fostering new collaborations.  Contact Alexander Haber for Zoom links

This event is generously supported by the McDonnell Center for the Space Sciences.

St. Louis Astronomical Society Meeting - Quasars: Black Holes, Bright Lights!

Quasars are very bright, very distant objects first found by the powerful radio waves that many emit. They must generate tremendous amounts of energy to be visible across a billion or more light years. Dr. Kimball will explain how quasars are detected and mapped and why astronomers think that supermassive black holes are linked to the quasar power source. She will also talk about her work with the Very Large Array, an interconnected group of twenty-seven massive radio telescopes, each with a disk over eighty feet across.   

Dr. Amy Kimball is a staff scientist at the NRAO headquarters in Socorro, NM. She assists astronomers worldwide who use the Jansky Very Large Array (VLA) radio telescope facility.  She is also the Head of Operations of the VLA Sky Survey, which is in the process of imaging the entire radio sky visible from New Mexico.  Dr. Kimball uses the VLA and other telescopes (both radio and non-radio) to study the demographics of quasars--- super-massive black holes at the centers of large galaxies.

The St. Louis Astronomical Society is an organization for individuals interested in astronomy and telescopes. The public is invited to attend its meetings, telescope observing sessions, and special events. For more information about Astronomical Society events, please visit  www.slasonline.org  or call 314-962-9231.

St. Louis Astronomical Society Meeting - Standing on the shoulders of Apollo 15

While millions dream of traveling to the Moon, only 24 people have had an opportunity to do it. This talk aims to take listeners on a multimedia journey through space and time. We will traverse the intersection of science and exploration from Apollo 15, to the upcoming Artemis mission in 2024. Apollo 15, which just celebrated its 49th anniversary, was the first of what was called the Apollo "J" missions. Apollo 15 was capable of a longer stay time, greater surface mobility, and more significant science than previous missions. When we return to the Moon with Artemis, we will be building upon Apollo, advancements in human spaceflight from the shuttle and International Space Station, and commercial and international partnerships. Apollo and Artemis are benchmarks for what is, and what can be possible for lunar exploration. As Isaac Newton wrote in the 17th century, "If I have seen further, it is by standing on the shoulders of giants."

The St. Louis Astronomical Society is an organization for individuals interested in astronomy and telescopes. The public is invited to attend it's meetings, telescope observing sessions, and special events. For more information about Astronomical Society events, please visit www.slasonline.org or call 314-962-9231.

St. Louis Astronomical Society Meeting - Water, water, everywhere

“Water, water, everywhere: from the study of meteorites to the origin of Earth's water”, a presentation by Dr. Lionel Vacher of Washington University, will be featured at the September meeting of the Saint Louis Astronomical Society. The meeting will be held via Zoom online conference only, due to the COVID-19 outbreak. The meeting and lecture will begin at 7:30 p.m. on Friday, September 18. Zoom access information is posted on the Society’s website, https://www.slasonline.org/. The event, cosponsored by NASA's Missouri Space Grant Consortium, is open to the public free of charge. 

Over 70% of the Earth’s surface is covered with water, to an average ocean depth of almost 2.5 miles. Where did all that water come from?  The origin of Earth’s oceans is a major topic of modern planetary science research. Most theories about the formation of the Earth propose that our planet formed too close to the Sun to retain large quantities of water. Dr. Vacher will explain the leading theories for the original source of Earth’s water, and indicate how his own studies of certain types of meteorites may provide some answers to water questions. 

Dr. Lionel Vacher is a Postdoctoral Research Associate in the Department of Physics at Washington University and a member of the McDonnell Center for the Space Sciences.  His primary research interests include “primitive” meteorites, the origin of water in the solar system, the effects of water on meteorite chemistry, and hydrothermal experiments. 

The St. Louis Astronomical Society is an organization for individuals interested in astronomy and telescopes. The public is invited to attend its meetings, telescope observing sessions, and special events. For more information about Astronomical Society events, please visit https://www.slasonline.org/, or call 314-962-9231. 

Oligocrystalline FeMnAlNi Shape Memory Alloys: Microstructural Evolution, Scale-up, Magnetic Sensing

IMSE presents the North American Materials Colloquium Series

For the link to the synchronous presentation and live Q&A session (9/24 2-3:15PM or 9/25 3-4:15PM):  RSVP Here

Asynchronously view the presentation ONLY here:  Asynchronous Presentation (link not live yet)

FeMnAlNi alloys have emerged as one of the most promising SMA candidates for large scale structural applications due to their cost-efficiency, excellent superelasticity and low temperature dependence of the critical stress levels with a large superelasticity window.

The superelastic performance of FeMnAlNi is highly dependent on the size of nano-precipitates, the crystallographic orientation of the individual grains and the ratio of relative grain size to the dimension of component. When subjected to loading, FeMnAlNi alloys show a change in metamagnetic response where deformations can be easily detected by the magnetization response of the alloy. From an application point of view, this property can be harnessed as a non-contact strain sensor in the next generation of structural monitoring applications. The fundamental understanding of the microstructure and the ability to increase the component dimension of the alloys for large scale applications is therefore of considerable importance in the development of FeMnAlNi alloys.

In this study, the fundamental mechanisms behind the abnormal grain growth triggered by thermal cycling was studied. A new crystal reorientation mechanism that results in abrupt crystallographic orientation changes in bulk single crystals is reported for the first time.

Then, a new FeMnAlNi SMA cable was developed and showed that favorable wire properties can be scaled into larger assemblies. Finally, FeMnAlNi was developed as a non-contact sensor to monitor stresses and strains in structural systems. It was found that the magnetic characteristics of the alloy changes when the stresses are applied, and a direct correlation was established between the magnetic response and the remnant deformation. The result of this study is a first step towards utilizing novel FeMnAlNi SMAs in next generation structural monitoring where structural and sensing elements are integrated. The findings also open up new possibilities for the development of new large single crystals with tailorable orientations.

Hande Ozcan is a postdoctoral researcher in the Department of Materials Science and Engineering at Texas A&M University. She earned a Ph.D. in mechanical engineering at Texas A&M University in 2020 advised by Professor Ibrahim Karaman and a B.S. in mechanical engineering from Hacettepe University in Turkey in 2010. Recently (2019) she was selected as one of the “Rising Stars in Mechanical Engineering” in a program funded by Stanford, MIT, and UC Berkeley. She served as a student board member for the Shape Memory and Superelastic Technologies International Conference between 2018-19 and is an active member of the Consortium for the Advancement of Shape Memory Alloy Research and Technology (CASMART), which has member organizations from industry (including Boeing, GM, Rolls-Royce, Fort Wayne, Dynalloy), academia (TAMU, Colorado School of Mines, Northwestern, UNT), and government (Sandia, NASA). During her doctoral studies, she mentored six engineering undergraduate researchers for their independent research and was awarded a graduate teaching fellowship to instruct a sophomore level material science and engineering course.

St. Louis Space Frontier Meetup

Standing on the Shoulders of Giants: Apollo to Artemis and Beyond, a presentation by Jeff Gillis-Davis of Washington University will be featured at the September meeting of the St. Louis Space Frontier. Zoom access information will be revealed when people RSVP for the event at https://www.meetup.com/Saint-Louis-Space-Frontier-Meetup/events/273219856.

The Apollo astronauts spent only 80 total hours of EVA (i.e., working/exploring) time on the Moon's surface. Combining knowledge from their brief forays with extensive analyses of Apollo samples and lunar meteorites, remote sensing data, experiments, and modeling, scientists have learned a significant amount about the lunar environment. NASA’s Artemis missions and Commercial Lunar Payload Services will enable scientists and engineers to examine the surface up close for the first time in half a century. These new missions for science and exploration will teach us how to conduct in situ resource utilization; navigate safely in extreme conditions; mitigate dust; how to build infrastructure with soil and on top of it; and how to keep humans safe in space. The techniques scientists will develop on the Moon will make it possible for humans to safely and sustainably explore farther destinations, such as asteroids and Mars.

Dr. Gillis-Davis has been a Research Associate Professor of Physics at Washington University since 2018. For the prior fifteen years, he worked at the University of Hawaii. His research there involved data from NASA’s MESSENGER mission, which orbited Mercury, and radar data from the Lunar Reconnaissance Orbiter Mission. At Washington University, he is the principal investigator of NASA’s Interdisciplinary Consortium for Exploring Volatile Origins. This team of international researchers studies the origin, evolution, and interactions of volatiles on the Moon and asteroids.

The Saint Louis Space Frontier is a chapter of the National Space Society. The NSS Vision is: People living and working in thriving communities beyond the Earth, and the use of the vast resources of space for the dramatic betterment of humanity. The chapter meets monthly, participates in outreach events, has fun at social events, and hosts the Gateway to Space Conference each fall. For more information about the St. Louis Space Frontier, please visit: http://stlouisspacefrontier.org/.

"Giant Piezo-Driven Multiferroic Heterostructures by Design” and “Solute Characterization of (Zr,Ta)B2 Ceramics"

For the link to the synchronous presentation and live Q&A session (10/1 2-3:15PM or 10/2 3-4:15PM):  RSVP Here

Asynchronously view the presentation ONLY here:  Asynchronous Presentation (link not live yet)

Two presentations will be given in today’s seminar slot:

“Giant Piezo-Driven Multiferroic Heterostructures by Design”

Shane Lindemann
Graduate Student
University of Wisconsin–Madison

Electric-field control of magnetic properties, i.e. the converse magnetoelectric (ME) effect, offers opportunities for both fundamental scientific research as well as the development of multifunctional devices. In particular, strain driven ME coupling in ferroelectric (FE) / ferromagnetic (FM) heterostructures provides an encouraging route to realizing the next generation of low-power memory storage and sensing technologies.  The key lies with the use of relaxor-ferroelectrics such as Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT), whose giant piezoelectricity allows for large strains under an electric field.  By coupling with a FM overlayer with large magnetostriction, transfer of strain from the FE into the FM can result in piezo-driven control of both the direction and strength of the FM’s in-plane magnetic anisotropy.

Achieving low-power means that thin films of PMN-PT must be used; however, their implementation faces two significant challenges: 1) Mechanical clamping by passive substrates nearly eliminates piezoelectricity in thin films. 2) Rotation of the in-plane anisotropy of the FM requires anisotropic in-plane strains.  Our unique approach involves growth of (011) oriented epitaxial PMN-PT thin films, which can generate the desired uniaxial in-plane strains, followed by complete removal of the substrate to create PMN-PT membranes.

First, I will show how magnetoelectric coupling of the PMN-PT membranes with Ni overlayers results in piezo-driven control of the Ni layer’s magnetic anisotropy over a range of only 3V, two orders of magnitude lower than the 100s of volts required using bulk single crystal PMN-PT.  I will also discuss how the PMN-PT membranes can be used to create novel heterostructures via the process of crystal stacking [Nature 578, 75–81 (2020)], circumventing obstacles posed by the conventional method of heteroepitaxy.  This approach provides an innovative platform for the design and discovery of new strain-mediated phenomena.

Shane Lindemann is a graduate student in the Materials Science and Engineering Department at University of Wisconsin-Madison (UW).  He received a B.S. in civil engineering at Louisiana State University (LSU) in 2015, where he also completed minors in physics and materials science that motivated him to pursue a Ph.D. in materials science. He is a member of the UW Oxide Lab, under the advisement of Dr. Chang-Beom Eom, where his research focuses on studying the magnetoelectric coupling in multiferroic thin film heterostructures utilizing giant piezoelectricity.  He co-authored six publications including one in Nature [“Heterogeneous Integration of single-crystalline complex-oxide membranes” Nature 578, 75 (2020)]. In this paper, Shane and his collaborators demonstrated the creation of artificial heterostructures through crystal-stacking, allowing for the combination of layers with different crystal structures that cannot be combined by conventional heteroepitaxy. Throughout his academic career, Shane enjoyed teaching/tutoring experiences in the LSU departments of math and physics, as an MCAT physics instructor with the Princeton Review, and as a TA for two courses (MSE 333 and 434) at UW-Madison..

“Solute Characterization of (Zr,Ta)B2 Ceramics”

Anna Dorner
Graduate Research Assistant and Ph.D. Candidate
Missouri University of Science and Technology

Solute segregation was examined in zirconium diboride and zirconium-tantalum diboride solid solution ceramics that were produced by reactive hot pressing. Microstructural analysis demonstrated that the ZrB2 and (Zr,Ta)B2 ceramics reached nearly full relative density and were nominally phase pure. X-ray diffraction was consistent with full incorporation of Ta into solid solution within the ZrB2 structure, and energy dispersive spectroscopy demonstrated that tantalum was well-distributed throughout the bulk of the Ta-doped specimens. The weak characteristic x-rays for B led to inaccurate results for total atom concentrations in boride ceramics by energy dispersive spectroscopy. Atom probe tomography was used to analyze the amount and spatial distribution of Ta species. No obvious Ta segregation was observed in grains or grain boundaries. However, nitrogen strongly segregated to a grain boundary. This study demonstrated that atom probe tomography is an accurate method for characterizing the amount and spatial distribution of metallic and non-metallic species in ZrB2 ceramics.

Anna Dorner is currently a 4th-year Ph.D. student in ceramic engineering at Missouri University of Science and Technology, where she is a member of the ultra-high temperature ceramics research group headed by Dr. Bill Fahrenholtz and Dr. Greg Hilmas. Her graduate research interests are based in fundamental science studies of solid solution diboride materials. Her first publication on the characterization of diboride solid solutions was published in the Journal of the American Ceramic Society in December 2019, and her current research includes the effects of solute additions upon mechanical properties in ZrB2 and phase equilibria and diffusion in the ZrB2-TaB2 system. Anna was awarded “Outstanding Ceramic Graduate Student” by her department in Spring 2019. Prior to her time at Missouri S&T, she attended Purdue University where she earned a B.S. in chemistry with minors in materials science and Spanish in 2017.

Spin-triplet superconducting state in the nearly ferromagnetic compound UTe2

Our recent discovery of the novel spin-triplet superconductivity in UTe₂ has inspired a lot of interests in the community. Superconducting state of UTe₂ closely resembles that of ferromagnetic superconductors, but the normal state is paramagnetic and shows no indication of magnetic ordering. UTe₂ exhibits an extremely large, anisotropic upper critical field Hc2, temperature independent NMR Knight shift in the superconducting state, and a large residual normal electronic density of states. All these results strongly indicate that the superconductivity in UTe₂ is carried by spin-triplet pairs. Even more striking, superconductivity reenters in the magnetic field of 45 tesla and persists up to 65 tesla, which is the upper limit of magnetic field in our current study. These extreme properties reflect a new kind of exotic superconductivity rooted in magnetic fluctuations and quantum dimensionality. Application of pressure reveals a two-fold enhancement of this unusual superconductivity, which is closely related to the suppression of Kondo coherence. In this talk, I will review our recent results on UTe₂.

Sheng Ran’s research aims to realize and understand exotic states of quantum materials, using combined techniques of bulk crystal synthesis, electric and thermal transport measurements under extreme temperature, pressure and magnetic field conditions, and neutron and high energy X-ray scattering.

Discovering pathways to experimentally realize quantum phases of matter and exert control over their properties is one of the central goals of modern physics, which holds promise for a new generation of electronic devices with currently inaccessible and likely unimaginable functionalities. With the explosion in the field of quantum materials in the past decade, it is conceivable that a vast number of new materials with unprecedented quantum states and properties are yet to be discovered. This is exactly what Dr. Ran’s research lab is dedicated to: discovery, synthesis, characterization and control of novel quantum materials with emergent electronic and magnetic states.

Of particular interest are topological quantum materials showing the coexistence of topology and other quantum phases, e.g., superconductivity, magnetism, charge density wave and ferroelectricity. Interplay of topology and these quantum phases gives rise to a variety of exotic quantum states, including the quantum anomalous Hall effect, topological axion states, Majorana fermions, some of which have potential applications for quantum computing and spintronics. Even though topological revolution has been the central theme in condensed matter physics in the past decade, theoretical prediction and experimental realization of such composite topological quantum materials has just started, and extensive experimental efforts to discover and characterize new systems are desperately in need.

For the link to the synchronous presentation and live Q&A session (10/8 2-3:15PM or 10/9 3-4:15PM):  RSVP Here

The Subsurface Structure of Abraded Al Alloys and its Influences on Corrosion

Al alloys subjected to surface abrasion exhibit an altered surface layer (ASL) with unique microstructure as the result of heavy shear deformation. This ASL microstructure is extremely unstable even at room temperature (RT), and its evolution is strongly affected by sample geometry (bulk or TEM sample) and temperature. In the ASL on freshly-abraded Al-Zn-Mg-Cu samples, pre-existing η′/η precipitates and grain boundaries are deformed and bent toward the abrasion direction. After 7-day natural aging of the abraded bulk sample, ultrafine subgrains form locally in the ASL, while unusual Al₂Cu (θ) and MgxZny phases precipitate at these subgrain boundaries; however, some deformed η′/η precipitates decompose.

Repeated observation of this TEM specimen with storage at RT shows that more ultrafine subgrains and θ particles form in the ASL, and Zn diffuses out of MgxZny particles to form a Zn particle. These unusual Zn and θ phases continued to grow and coarsen during 42-month natural aging of the TEM specimens. Artificial aging of abraded bulk samples at 50 °C for 1 h significantly accelerate the formation of subgrains and θ particles in the ASL. Because of the unique ASL microstructure, abraded alloy surfaces exhibit a different corrosion resistance than the underlying substrate. The ASLs on Al-Zn-Mg-Cu alloys are preferentially attacked at lower potentials than the underlying substrates during potentiodynamic polarization in an NaCl solution, resulting in surface layer attack that would undermine any protective coating system. Long-term natural aging or short-period artificial aging increases the breakdown potential and improves the corrosion resistance of the ASL. The ASLs on AA2024 and sensitized AA5083 are more resistant to corrosion owing to the solute redistribution in the ASL. Clearly the details of the ASL microstructure and its evolution play a critical role in the corrosion properties of abraded Al alloys.

Shan-Shan Wang is currently a research associate in materials science and engineering and Fontana Corrosion Center at The Ohio State University (OSU). She earned her Ph.D. and M.S. in materials science from Harbin Institute of Technology in China, and B.S. in materials science and engineering from Kunming University of Science and Technology in China. She also came to the United States as a visiting student at OSU between 2011 and 2013. After receiving her Ph.D. in 2015, she came back to the Fontana Corrosion Center at OSU, where she has continued to perform research as a postdoctoral researcher (2015-2018) and research associate since 2018. Shan-Shan’s primary research interests are the relationships between processing, microstructure and localized corrosion of metals and alloys, galvanic corrosion of mixed-metal systems, and protective coatings.

For the link to the synchronous presentation and live Q&A session (10/8 2-3:15PM or 10/9 3-4:15PM):  RSVP Here

The Effect of Metal Incorporation on Properties and Critical Interfaces in GeTe-Based Devices

For the link to the synchronous presentation and live Q&A session (10/15 2-3:15PM or 10/16 3-4:15PM):  RSVP Here

"Non Linear Inverse Liquid Solid Chromatography…” and “Ultrabright Plasmonic-fluor as a Cross-platform Nanolabel for Femtomolar Detection of Bioanalytes"

For the link to the synchronous presentation and live Q&A session (10/22 2-3:15PM or 10/22 3-4:15PM):  RSVP Here

Liquid Metal Embrittlement Susceptibility of Zn-Coated Advanced High Strength Steels

For the link to the synchronous presentation and live Q&A session (10/29 2-3:15PM or 10/30 3-4:15PM):  RSVP Here

“Mechanically Reconfigurable Materials and Devices based on 2D TMD layers” and “Structural Supercapacitor Electrodes Based on Reduced Functionalized Graphene Oxide”

Two presentations will be given in today’s seminar slot:

For the link to the synchronous presentation and live Q&A session (11/5 2-3:15PM or 11/6 3-4:15PM):  RSVP Here

MAX Phases as Precursors to New MXenes

For the link to the synchronous presentation and live Q&A session (11/5 2-3:15PM or 11/6 3-4:15PM):  RSVP Here

“High Entropy Oxides: The Multicomponent Materials, Their Synthesis, and Properties” and “Strain-Induced Electrochemical Inhomogeneity in Cathode Nanoparticles Revealed at Atomic Level”

Two presentations will be given in today’s seminar slot

For the link to the synchronous presentation and live Q&A session (11/19 2-3:15PM or 11/20 3-4:15PM):  RSVP Here

St. Louis Astronomical Society Meeting - Mirror Asymmetry in Life and in Space

Most organic molecules exist in two forms that are mirror images of each other.  One of the great unanswered questions in our evolutionary history is why all life forms on Earth and their critical biological molecules, such as amino acids and proteins, use only one of these forms. For instance, sugars are exclusively right-handed, amino acids are left-handed, and even DNA coils into right-handed helices. The phenomenon of single handedness is called homochirality. How and why did our single-handed world emerge? Dr. McGuire will describe how we can peer into the center of our galaxy for the answer. He will also talk about the current understanding of how such an excess may have arisen in the interstellar medium and before the formation of the Solar System. 

Dr. Brett McGuire is an Assistant Professor of Chemistry at MIT. He and his colleagues use the tools of physical chemistry, molecular spectroscopy, and observational astrophysics to understand how the chemical ingredients for life evolve with and help shape the formation of stars and planets. 

The St. Louis Astronomical Society is an organization for individuals interested in astronomy and telescopes. The public is invited to attend its meetings, telescope observing sessions, and special events. For more information about Astronomical Society events, please visit www.slasonline.org or call 314-962-9231. The event, cosponsored by NASA's Missouri Space Grant Consortium, is open to the public free of charge. 

“Soft materials from block copolymer self-assembly: from bioinspired membranes to hierarchically-structured hydrogels” and “Nanoscale 4D Microstructural Characterization of Corrosion in High Performance Light Metal Alloys using Correlative Microscopy”

Two presentations will be given in today’s seminar slot:

For the link to the synchronous presentation and live Q&A session (12/3 2-3:15PM or 12/4 3-4:15PM):  RSVP Here

Mixed Phase Ytterbium Silicate Environmental-Barrier Coatings for Improved Calcium–Magnesium–Alumino-Silicate Resistance

For the link to the synchronous presentation and live Q&A session (12/10 2-3:15PM or 12/11 3-4:15PM):  RSVP Here

St. Louis Astronomical Society Meeting - Pulsars-Timekeepers of the Cosmos

Pulsars are neutron stars that are formed in supernova explosions following the collapse of massive evolved stars. These exotic objects are more massive than the Sun. They have been compressed by gravity into a sphere that is typically smaller than a city, and they can spin over 700 times a second. They have extremely high magnetic fields - over a trillion times the strength of Earth’s. These properties make them energetic sources of radio waves, which are beamed along their magnetic axes. We detect a "pulse" of radio emission once every pulsar rotation period, in a similar manner to a lighthouse. The rotation periods of pulsars can be measured incredibly precisely, making these "cosmic clocks" excellent laboratories for fundamental physics experiments. Dr. McLaughlin will give an overview of pulsars and their properties. She will also describe several recent highlights of pulsar research, including the search for gravitational waves from the most massive black holes in the universe. 

Dr. Maura McLaughlin is the Eberly Distinguished Professor of Physics and Astronomy at West Virginia University and Director of the Center for Gravitational Waves and Cosmology. She studies pulsars using the world's largest radio telescopes.  She is Co-Director of the NANOGrav Physics Frontiers Center, which aims to detect gravitational waves using high-precision timing observations of these cosmic clocks.  

The St. Louis Astronomical Society is an organization for individuals interested in astronomy and telescopes. The public is invited to attend its meetings, telescope observing sessions, and special events. For more information about Astronomical Society events, please visit www.slasonline.org or call 314-962-9231. The event, cosponsored by NASA's Missouri Space Grant Consortium, is open to the public free of charge.