Abstract
Bioaugmentation has emerged as an effective way to remediate groundwater of anthropogenic contaminants, such as chloroform (CF) and dichloromethane (DCM). The Dehalobacter genus can anaerobically respire many of these chlorinated compounds using reductive dehalogenases, often as part of a heterogenous microbial community. One such community is SC05, which dechlorinates CF completely to carbon dioxide and hydrogen. Despite its effective use at contaminated sites, prior to this work SC05 remained unstudied in terms of taxonomy and broader metabolism, without identification of the active DCM degrader(s?). This thesis seeks to ascertain key microbes in the culture and their metabolic mechanisms using experimental, metagenomic, and metabolic modelling approaches.
A unique characteristic of “self-feeding” is first established in SC05, wherein electron equivalents produced from DCM mineralization are harnessed for CF dechlorination. An SC05 subculture continually dechlorinated CF for over 1400 days with no exogenous electron donor. Dehalobacter was the only bacterial genus that grew in either the CF dechlorination or DCM mineralization phase, implicating it as a key mediator of both CF and DCM degradation. Dehalobacter expressed a single reductive dehalogenase that dechlorinates CF to DCM but has no activity on DCM, as well as the mec cassette—core proteins for DCM degradation. These two modules were within 10 kb in a single genomic neighbourhood.
Two unique Dehalobacter genomes were ultimately assembled, each of which encoded the acd- mec neighbourhood. When assessed pangenomically, this region was designated as a mobile genetic element resulting from horizontal gene transfer between Dehalobacter strains. Each strain could employ this shared genetic cargo to dechlorinate CF and mineralize DCM, with differing dynamics dependant on culture conditions. Genome-scale metabolic models of each strain were curated to predict and compare metabolism during each remediation step.
Overall, this work elucidates some of the former mysteries of SC05, informing considerations for field application such as electron donor demand. It also highlights the importance of hydrogen cycling and microbial syntrophy in anaerobic DCM degradation. Fundamentally, it expands the typical assumptions of the metabolic rigidity of Dehalobacter genus and posits mechanisms of evolution and horizontal gene transfer as it pertains to adaptation of microbial communities to anthropogenic chemicals.
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Abstract: Food fortification programs aim to provide meaningful amounts of micronutrients (e.g., 30%-50% of the daily adult requirements) at the average consumption level of one or more food vehicles. Foods that can be fortified include wheat and wheat products, maize, rice, milk and milk products, cooking oils, salt, sugar, and condiments. New vehicles widely and regularly consumed in certain regions, like bouillon cubes, flavouring sauces, or tea, are also gaining new attention. Micronutrient premixes for home fortification are also being promoted. Depending on the food processing methods, adding the micronutrients can be facilitated using different approaches to maximize nutrient retention. These include dry mixing, dissolution in water/oil, micronization, spraying, adhesion, coating, extrusion, micro-encapsulation, and dry mixing.
Cost, bioavailability, sensory acceptability, and stability (during storage and cooking) are the critical criteria for determining the best match between the nutrient and food vehicle. When added to food or beverage carriers, specific vitamins and minerals could interact with each other and the food, reducing their bioavailability and organoleptic quality. The development of appropriate technology to optimize the effectiveness of fortification needs special attention.
Better refining procedures and packaging have significantly improved the stability of iodine compounds in salt and vitamin A in cooking oils. The structure of the compounds can also be modified to improve absorption. In the case of iron, stabilizers, chelating agents, and absorption enhancers could be added along with the fortificant to retain it in an absorbable form or improve absorption. The extrusion and micro-encapsulation of micronutrients can ensure nutrient stability while ensuring breakdown and absorption in the gut. Technological improvements in the analytical methods for testing fortified foods have been developed specifically to monitor nutrient retention from production to consumption.
Speaker Bio
M.G. Venkatesh Mannar has pioneered several effective international nutrition, technology, and development initiatives focused on the world’s most vulnerable citizens. A chemical engineer and food technologist by training, Mannar served as the President of the Micronutrient Initiative Canada (MI) for nearly 20 years until February 2014. He directed the organization’s mission to develop, implement, and monitor cost-effective and sustainable solutions to address micronutrient deficiencies. Mannar’s work has focused on the world’s most vulnerable citizens, including staple food fortification, vitamin A supplementation, and scale-up of biofortified food production and marketing. His work on iodization and multiple fortification of salt has been scaled up to benefit billions of people worldwide. The double-fortified salt (with iron and iodine) and multiply fortified salts he worked on at the University of Toronto are being scaled in India and other countries. He has co-authored over 100 articles in leading nutrition journals and is the co-editor of ‘Food Fortification in a Globalized World. Mannar pursues research and teaching as an Adjunct Professor at the Centre for Global Engineering at the University of Toronto. He was co-chair of the Independent Expert Group for the Global Nutrition Report 2020 – the leading and most authoritative report on Global Nutrition. He has also served on the Technical Advisory Boards of leading multinational food companies. In 2013, Mannar was appointed an Officer of the Order of Canada, one of the country’s greatest civilian honors, for his leadership in the global fight against malnutrition and micronutrient deficiency. In 2015, the Indo-Canada Chamber of Commerce felicitated him with an Outstanding Lifetime Achievement Award. In Jun 2016, he was conferred with an Honorary Doctor of Science Degree by the University of Toronto.
Dr. Jean-Christophe Leroux
Full Professor at the Department of Chemistry and Applied Biosciences
Deputy Head of Institute of Pharmaceutical Sciences, ETH Zürich
Abstract
Three-dimensional (3D) printing is a versatile technology enabling the cost-effective production of personalized medical devices. Among various 3D printing methods, digital light processing (DLP) stands out for its ability to rapidly create objects with high precision. However, the fabrication of bioresorbable medical devices using DLP is in part limited by the limited choice of suitable biomedical inks. In this study, we developed innovative polyester-based inks enabling DLP printing of therapeutic devices with adjustable mechanical characteristics and degradation profiles. The most promising materials were utilized to design biodegradable customized airway stents. These stents degraded into soft hydrogels in vitro and completely disappeared seven weeks after insertion in rabbits. Additionally, the 3D printed stents could be loaded with drugs like levofloxacin or nintedanib, and their release kinetics could be tailored by modifying the copolymer composition. Furthermore, we engineered near-infrared (NIR) light-responsive stents containing gold nanorods using tunable ink compositions. This allowed for the creation of shape-memory stents that expand upon NIR light activation, facilitating easy deployment. Lastly, DLP served as a prototyping method for the fabrication and optimization of mucosal suction patches investigated for transbuccal drug delivery. These studies open new perspectives for the rapid manufacturing of complex devices with superior properties.
Speaker Bio
Jean-Christophe Leroux is a full professor of Drug Formulation and Delivery at the Institute of Pharmaceutical Sciences at the ETH Zurich, Switzerland. He has made important fundamental and applied contributions to the fields of biomaterials and drug delivery and has been involved in the development of innovative bio-detoxification systems for the treatment of metabolite disorders. He is a fellow of the AAPS, EURASC, French Academy of Pharmacy, and the CRS, and the co-founder of the start-up pharmaceutical companies Versantis AG, Inositec AG and OBaris AG.
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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