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May6
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lessAbstract- The fracture and fatigue of soft materials are tightly coupled to the topology of polymer networks. Achieving control over this topology and identifying the relation between topology and fracture/fatigue resistance are central to advancing the design of soft materials. In this talk, I will first review the importance of entanglement in the design of the elastic and fracture properties of polymer networks. Next, I will introduce two approaches that can engineer entanglements by mechanically and kinetically intervening in radical polymerization. Finally, I will discuss the molecular understanding of fracture-resistance dynamics in polymer networks. Specifically, I will show that UV light intensity influences entanglement formation in photopolymerized polymer networks. I will also discuss how applying mechanical stimuli via focused ultrasound during polymerization can control topology beyond thermodynamic equilibrium. These approaches are demonstrated using highly entangled hydrogels, which show significant differences in elastic and fracture properties due to the engineered polymer network topology. When a polymer topology is given, the toughness of polymer networks can be understood in terms of molecular structure. Through controlled material synthesis and the quantification of fracture resistance, we advance understanding of the time dependence of toughness in organogel and the fatigue threshold of LDPE thermosets. Our work expands the accessible design space for polymer network topology and offers new routes to tune mechanical response and fracture behavior in soft materials with molecular understanding.
Bio- Junsoo Kim is an assistant professor of Mechanical Engineering at Northwestern University. He earned his Ph.D. in the Material Science and Mechanical Engineering department at Harvard University in 2022, followed by postdoctoral training at Harvard University. Before joining Harvard in 2017, he was a researcher at Electronics Telecommunications Research Institute. He earned his M.S. in 2013 and B.S. in 2011 at Seoul National University. He has co-authored about 40 papers in peer-reviewed journals such as Science, Nature, Advanced Materials, etc, and has contributed to the field of mechanics of soft materials. He is selected as a Kavli Frontiers of Science Fellow by the National Academy of Sciences and Scialog Fellow by the Research Corporation for Science Advancement, and received the 9th Hanwha Non-Tenure Faculty Award from Hanwha Group and Haythornthwaite Foundation Research Initiation Grant.
TIME Wednesday, May 6, 2026 at 11:00 AM - 12:00 PM
LOCATION A230, Technological Institute map it
CONTACT Andrew Liguori andrew.liguori@northwestern.edu EMAIL
CALENDAR McCormick - Civil and Environmental Engineering (CEE)
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May8
EVENT DETAILS
lessAbstract: Coral reefs face significant challenges under rapid environmental change, driven by human activity throughout the last century. Steadily increasing sea surface temperatures, in conjunction with dramatic marine heat waves, induce an environmental stress response in corals that often leads to bleaching and death. During heat stress, corals must respond rapidly at the cellular level to regulate molecular processes and improve their chances of survival. Previous studies have characterized several transcriptomic shifts associated with the coral heat stress response. However, the upstream epigenetic mechanisms that regulate gene expression remain largely unknown in these organisms. To address this, we focused on chromatin packing, a process that controls the accessibility of genes to transcriptional machinery via chemical modifications of histone proteins. To study these mechanisms, we adapted a Chromatin Immunoprecipitation sequencing (ChIP-seq) protocol for reef-building corals. This technique uses immunoprecipitation to map enrichment of histone post-translational modifications across the genome through sequencing. After verifying the robustness of this protocol in coral tissues, we deployed ChIP-seq during an acute 24-hour heat stress assay to measure early epigenetic responses in the coral Pocillopora damicornis. To confirm whether specific histone modifications resulted in concomitant shifts in gene expression, we performed mRNA-sequencing at identical time points. We identified significant changes in the coral epigenome as early as ~3 hours after initiating heat stress, with differences increasing in magnitude under prolonged exposure. Notably, we observed significant increases in H3K27 acetylation—a marker associated with active transcription—on genes involved in protein misfolding, immune responses, cell signaling, and transcriptional regulation. In parallel, a loss of H3K27 acetylation was observed in genes related to transmembrane transport and metabolic processes. These findings are consistent with the cellular stress responses outlined in previous literature and provide novel mechanistic insight into how corals rapidly regulate their survival at the epigenetic level. To our knowledge, this study represents the first locus-specific epigenetic profiling of corals during heat stress.
Biosketch: George Warfel is a fourth-year undergraduate at Northwestern University studying Chemical Engineering and Biological Sciences. He works in the Marcelino lab within the Civil and Environmental Engineering department and Center for Physical Genomics and Engineering. His research focuses on probing the molecular mechanisms that drive environmental stress responses in reef-building corals using next-generation sequencing techniques. He was recently awarded the NSF Graduate Research Fellowship and plans to continue his studies at a PhD program in bioengineering or molecular sciences.
TIME Friday, May 8, 2026 at 2:00 PM - 3:00 PM
LOCATION A230, Technological Institute map it
CONTACT Andrew Liguori andrew.liguori@northwestern.edu EMAIL
CALENDAR McCormick - Civil and Environmental Engineering (CEE)
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May15
EVENT DETAILS
lessTBA
TIME Friday, May 15, 2026 at 2:00 PM - 3:00 PM
LOCATION A230, Technological Institute map it
CONTACT Andrew Liguori andrew.liguori@northwestern.edu EMAIL
CALENDAR McCormick - Civil and Environmental Engineering (CEE)
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May21
EVENT DETAILS
lessTBA
TIME Thursday, May 21, 2026 at 11:00 AM - 12:00 PM
LOCATION A230, Technological Institute map it
CONTACT Andrew Liguori andrew.liguori@northwestern.edu EMAIL
CALENDAR McCormick - Civil and Environmental Engineering (CEE)
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May27
EVENT DETAILS
lessTBA
TIME Wednesday, May 27, 2026 at 11:00 AM - 12:00 PM
LOCATION A230, Technological Institute map it
CONTACT Andrew Liguori andrew.liguori@northwestern.edu EMAIL
CALENDAR McCormick - Civil and Environmental Engineering (CEE)
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May29
EVENT DETAILS
lessTBA
TIME Friday, May 29, 2026 at 2:00 PM - 3:00 PM
LOCATION A230, Technological Institute map it
CONTACT Andrew Liguori andrew.liguori@northwestern.edu EMAIL
CALENDAR McCormick - Civil and Environmental Engineering (CEE)