Abstract
Topological structures in ferroic materials can emerge as particle-like objects such as skyrmions
and merons, with real-space swirling arrangements of the order parameter that not only have
mathematical beauty but hold promise for potential applications in next generation nanodevices.
As those ferroic textures are intrinsically nm-scale and dynamic, developing methods for
visualizing and characterizing their detailed 3D structure is a critical step in understanding their
properties and exploring possible phase transitions. I will show how the measurement of
structural information such as polarization, strain, chirality, electric or magnetic fields was made
possible by new imaging methods, i.e., four-dimensional scanning transmission electron
microscopy (4D-STEM) diffraction imaging. I will report the observation of room temperature
Néel-type skyrmion in a van der Waals ferromagnet accompanied by a change in crystallographic
symmetry and chemical order. Second, I report the emergence of achiral polar meron lattice
(topological charge of +1/2) from disordered but chiral skyrmion (topological charge of +1) phase
transition driven by elastic boundary conditions. Further, using multislice electron ptychography,
the 3D structural distortions of unknown polar textures in complex oxide heterostructures can
be resolved at unprecedented resolution and precision.
Speaker Bio
Yu-Tsun Shao studies quantum materials by novel electron microscopy techniques, specifically
4D-STEM. He studies the (multi-)ferroic crystals with the aim to elucidate the microscopic origin
of interactions among local polar/magnetic order, strain, and chiralities during topological phase
transitions. Before joining USC, Yu-Tsun did postdoctoral work in Professor David Muller’s group
at Cornell University and received his Ph.D. in Materials Science and Engineering at the University
of Illinois at Urbana-Champaign in 2018, under the mentorship of Professor Jian-Min Zuo.
Abstract
Bioresource materials such as cellulose, chitin, and lignin, are usually low-cost, biocompatible, and abundant in nature. The synthesis of functional materials from these bioresource materials can address long-term challenges in Food-water-Energy Nexus, such as resource and energy depletion, food security, water scarcity, and climate change. However, the adaption of chemical functionalization and self-assembling methodologies to renewable resource materials for functional materials is very challenging due to their macromolecular structures, heterogeneous properties, poor solubility, and the disturbance of impurities. In this talk, we will summarize how we explore self-assembly methods to produce new nanostructures and endure new functions for renewable resource materials. Several examples will be discussed. For example, glycerol, a biowaste from the biodiesel process, has been assembled into a nano-core-shell structure for a smart food packaging film sensor for universal real-time food spoilage monitoring. Biomass waste or cellulose can be assembled as multiple-function controlled-release fertilizers and smart membranes. Ultimately, we would like to use these self-assembly nanostructures from renewable resources to achieve a high-efficiency circular bioeconomy.
Speaker Bio
Dr. Tong has been an Associate Professor and James C. Barber Faculty Fellow in the School of Chemical and Biomolecular Engineering at Georgia Tech since January 2022. She is also the initiative leader in waste valorization in the food-water-energy nexus of the Renewable Bioproduct Institute (RBI). Previously, she served as an assistant and associate professor since 2010 at the University of Florida. She earned her Ph.D. in chemical engineering from Georgia Tech in 2007, followed by work at Ch2M Hill until 2009. Tong’s research focuses on synthesizing functional sustainable materials and catalytical conversion for biochemicals and biofuels from renewable resources. She has published 73 journal papers and 4 patents. Her research has been supported by NSF, USDA, NAS, and DOE. She secured about $5 million in grants after joining Georgia Tech in 2022. Dr. Tong has also served as an associate editor for three journals and held leadership roles in AIChE.
Abstract
In the last 20 years, significant efforts have been invested in developing adsorption processes for CO2 capture. The explosion in adsorbent synthesis and molecular simulations has generated hundreds of thousands of (hypothetical & real) adsorbents, e.g., Zeolites, Metal-Organic Frameworks (MOFs). This excitement has led to an implicit assumption that the key bottleneck in developing large-scale adsorption processes is discovering the right adsorbent. However, the practical reality is quite different. Very few successful examples have moved from the lab(or computer) to an industrial scale. In this talk, we will highlight some modelling and experimental tools we have been developing to enable screening and discovery of CO2 capture sorbents. On the modelling side, we will discuss simulation tools that enable process-informed screening of sorbents. On the experimental side, a major challenge for both process upscaling and molecular modelling is the lack of multi-component adsorption equilibria, particularly CO2-N2, CO2-water vapour and CO2-steam. We will discuss our efforts in developing experimental techniques to measure such data on small samples and highlight recent results showing multicomponent adsorption data on various CO2 capture MOFs. We will highlight our experience measuring multi-component data on Calgary framework-20 (CALF-20), perhaps the first MOF to be scaled up for industrial CO2 capture., and other CO2 capture MOFs.
Biography
Arvind Rajendran is a professor of Chemical Engineering at the University of Alberta. He received his PhD from ETH Zurich and started his academic career at Nanyang Technological University, Singapore, before moving to the University of Alberta in 2012. He has co-authored over 90 papers and (co-) advised 50+ highly qualified personnel. His research group focuses on adsorptive gas separations with applications in CO2 capture, direct air capture, oxygen purification and helium separation. Between 2016 and 2020, he served as an associate editor of the Canadian Journal of Chemical Engineering and as an area editor of Adsorption- the journal of the International Adsorption Society.
Abstract
Immunotherapy has revolutionized the field of cancer treatment over the past two decades, though only a small fraction of patients treated will achieve complete remission. As such, new paradigms to overcome resistance to immunotherapies are urgently needed. My research seeks to tailor immunotherapies towards individual differences in immune systems and the inherent heterogeneity of cancer. For this talk, I will share my work on a key therapeutic target against cancer called the STimulator of INterferon Genes (STING) signaling. I first addressed an innate immunodeficiency caused by a loss-of-function mutation of STING protein affecting 20% of the human population, using the cytosolic domain of STING (STINGΔTM) as a functional agonist carrier to activate signaling in STING-deficient cells. Subsequently, I developed a therapeutic cancer vaccine based on this platform by fusing STINGΔTM with immune checkpoint blockade (ICB) nanobodies. The treatment eliminated subcutaneous colon and melanoma tumors in 70-100% of mice and protected all cured mice against rechallenge, while mechanistic studies revealed a distinct STING-mediated anti-tumor immunity driven by robust TH1 polarization and Treg suppression in CD4+ T cells, followed by the collaboration of CD8+ T and NK cells to eliminate tumors. For my independent group, I will continue these prospects in designing protein therapeutics and leveraging the full potential of CD4+ T cells, initially towards personalized cancer immunotherapies and expanding to other monogenic immunodeficiencies and drug delivery challenges in the long run.
Speaker Bio
Yanpu He is an incoming assistant professor at the School of Biomedical Engineering at the University of British Columbia (UBC), starting Jan. 2025. He completed his postdoctoral training with Prof. Angela Belcher in the Department of Biological Engineering at the Massachusetts Institute of Technology (MIT) from 2021 to 2024, and his Ph.D. in Chemical Engineering at MIT in 2021, co-advised by Profs. Paula Hammond and Darrell Irvine. He received MIT Marble Center Cancer Nanomedicine postdoctoral fellowship from 2021-2023 and was named Convergence Scholar at MIT Koch Institute in 2021. His research focuses on protein and cellular engineering to develop immunotherapies for cancer, infectious disease, and neurodegenerative disorders.
Abstract
In recent years, there is a strong interest in ptychography, which computationally constructions a model of the sample from series of diffraction data collected from electron microscopes [1]. We have demonstrated a resolution of 0.67 Å or better using ptychography with a 20 keV electron beam operating in a transmission mode using a SEM with a cold emission gun and immersion lens.
We achieved this through combination of: adding a simple diffraction projector lens to our SEM; using an un-coated hybrid direct electron detector [3]; and incorporating correction of diffraction
projector distortions within a multi-slice ptychographic reconstruction process. Measurement and corrections of lens distortions is in general not trivial, so in our work we have simplified distortion evaluation using machine learning methods, as will be described. Also, using low energy scanning transmission electron diffraction in a SEM has provided us very valuable information for understanding the structure of novel polymer structures, as will be illustrated. These advances serve to widen access to, and hence help democratize, information that is currently only available from high-end TEM. At low bean energies interesting possibilities are presented with computationally assisted SEM, particularly with imaging thin, low atomic-number based samples, which present greater information at lower energies. This may in the longer-term assist in the structural determination of proteins with masses below about 100 kDa.
Speaker Bio
Arthur Blackburn is the Hitachi High-Tech Canada Research Chair, Co-Director of the Advanced Microscopy Facility and Assistant Professor in the Department of Physics and Astronomy at the
University of Victoria. Prior to joining the University of Victoria, he was a Senior Research Scientist in the Hitachi Cambridge Laboratory, embedded with the Cavendish Laboratory of the University of Cambridge. He progressed to this role after completing his PhD within the University of Cambridge, Department of Physics.
Abstract
Manipulating the structure and chemistry of grain boundaries and interphase interfaces in crystalline materials are crucial to obtain materials with desirable physical and functional properties. Although there are many experimental studies on grain boundary segregation in various alloys and ceramics, the study of the transformation from the initial solid solution structure at the atomic scale have not been explored. In this study, a novel bicrystal technique was developed to produce yttria stabilized zirconia (YSZ) bicrystal specimens without Y3+ segregation to the grain boundary. Scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy (EDS) characterization confirmed that the specimen is indeed free of Y3+ segregation. To trigger grain boundary segregation, the specimen was annealed at various temperatures and the structure and chemistry were tracked by atomic resolution STEM imaging and EDS mapping. The fundamental understanding of the segregation sequence, as well as the conditions that can activate solute segregation are important for tailoring the properties and behaviour for the specific applications of YSZ, including solid electrolyte for solid oxide fuel cells (SOFCs) and cutting tools.
Speaker Bio
Jason Tam is currently a postdoctoral researcher at The University of Tokyo. He received his B.A.Sc. and Ph.D. from the Department of Materials Science and Engineering, University of Toronto. During his graduate study, he was also a visiting scholar at Hokkaido University and The University of Tokyo. Prior to his current position in Japan, he took on several roles at the University of Toronto as a postdoctoral researcher, undergraduate course instructor, and research scientist supporting the operations of the electron microscopy facility in OCCAM. His research interests include physical metallurgy, specifically interfaces of materials, electrochemical synthesis of nanostructured materials, and electron microscopy.
Speaker Bio
Dr. Fernando Morgan is the Technology Strategy Manager at AnoxKaldnes-Veolia Water Technologies. Fernando completed his MASc and PhD in the Department of Chemical Engineering and Applied Chemistry at the University of Toronto, working on the biofiltration of air emissions and biological wastewater treatment in the pulp and paper industry. He has over 20 years of environmental process engineering including a Post-doctoral fellow (Applied microbiology) at UGhent (Belgium) and Aalborg Univ. (Denmark). He has been at AnoxKaldnes since 2007 working on a variety of innovative biotechnologies for waste treatment and production of value-added products.
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Abstract
Polymer blends and polymer-based nanocomposites are multiphase materials that are present in many applications due to the interesting properties that they present. The challenge in their design relies on a proper control of their morphology, which, in turn controls their engineering properties. In this talk, it will be shown how rheology can be used as a tool to characterize and control the morphology of these materials. Some applications in the fields of energy and separation membranes will be discussed.
Speaker Bio
Nicole Raymonde Demarquette received her B.Eng. from the Institut Polytechnique de Grenoble, France, as well as, a Diplôme d’Études Approfondies in Chemical Engineering from the same institute. Then, she received a M.Sc. and a Ph.D. in Chemical Engineering from McGill University, Montreal, Canada. She also obtained a Livre-docência in Materials Engineering from the University of Sao Paulo, Brazil where she was a Professor between 1996 and 2012. In 2012, she returned to Canada and joined École de Technologie Supérieure in Montréal. She presently holds a Tier 1 Research Chair in Rheology to develop Novel Polymer Blends and Nanocomposites. She is the author or coauthor of more than 160 publications, several review papers and book chapters.
Durgesh Prasad Kavishvar
Doctor of Philosophy
Department of Chemical Engineering University of Toronto
Abstract
Yield stress is a characteristic stress depicting the flow behavior of many complex materials. When the applied shear stress is lower than yield stress, materials exhibit solid-like behavior, transitioning to liquid-like behavior for shear stress>yield stress. Conventional rheometers often struggle with sensitivity in measuring low yield stress, lack real-time measurement capabilities, and are prohibitively expensive. These limitations are particularly pronounced in biological materials such as blood and mucus, where variations in yield stress can signify underlying health conditions. For instance, yield stress of blood from patients with cerebrovascular and cardiovascular diseases, hypertension, sickle cell disease, among others, exceeds that of healthy blood. Similarly, yield stress of mucus from individuals battling conditions such as cystic fibrosis or asthma can be several orders of magnitude higher than that of healthy lung mucus. Also, yield stress measurements prove valuable for quality assessment in various industries such as oil & gas as well as food industry.
In this work, we investigate, through experiments, scaling analysis, and simulation, the yielding behavior of various complex materials in a Hele-Shaw microfluidic extensional flow device (MEFD). We propose the MEFD as a new microfluidic rheometer capable of measuring a low yield stress ranging from 5 mPa−5 Pa. The design of the MEFD is such that it enables a gradient in shear stress, shear stress, such that shear stress is lower near the center or stagnation point, and higher away from the stagnation point. For a yield stress fluid, we observe that, below a certain flow rate, shear stress exceeds yield stress only in the outer region, leading to stagnation or unyielding of the fluid in the inner region. Our simulation study also corroborates the experimental findings, demonstrating the existence of an unyielded region near the stagnation point of the extensional flow. We apply scaling analysis to deduce yield stress by measuring this size of the unyielded region at center. We validate the scaling relationship using Carbopol solutions of various concentrations (0.015 to 0.3%), measuring yield stress as low as ~10 mPa to ~1 Pa, and comparing these measurements with a standard rheometer.
Furthermore, we showcase the applicability of our rheometer by measuring yield stress of human blood samples ranging between 30−80 mPa for a range of hematocrits as well as yield stress of porcine gastric mucins (20%) of 0.7 Pa. We also demonstrate measurements of yield stress of clay suspensions (2 to 6%), useful in oil & gas applications. We also show a proof of concept for food industry by measuring yield stress of a lactic drink of roughly 7 mPa. Our microfluidic rheometer offers several other advantages, including real-time measurement capability (with measurement time as short as 4 s), low volume requirement (<1 ml), ease of cleaning and reuse, and cost-effectiveness. Therefore, it attracts diverse applications in clinical research, particularly in disease detection, as well as in industries such as food and oil & gas for quality assessment.
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A U of T Engineering startup co-founded by Adnan Sharif (ChemE MEng student) has its roots in an experience that is all too common for many of us — he kept forgetting to water his plants.
“I was working in a plant immunity biology lab, so if I didn’t water them, I’d have no plants to do experiments with,” says Sharif.
At the time, Sharif was a U of T undergraduate student working with Professor Keiko Yoshioka in the Department of Cell & Systems Biology. He has since graduated and is now pursuing an MEng in the Department of Chemical Engineering & Applied Chemistry.
“My dad is a mechanical engineering professor at a university in Japan, and he knows a lot about manufacturing materials with porous, three-dimensional structures. So that’s how I got the idea to make my own 3D printed soil construct, which could retain water for a week or more. That way, I wouldn’t have to go into the lab and water the plants so often.”
Today that product is called SmartSoil, and it’s one of the key innovations at the heart of Lyrata, a startup that is producing edible crops for caterers and high-end restaurants across the Greater Toronto Area.
Support from the U of T Engineering community has been key to Lyrata’s success. For example, it was a U of T Engineering alumni connection that recently led to Lyrata launching an installation at Casa Loma, a historic museum and landmark in midtown Toronto.