Seminar Series

The Chemical and Biochemical Engineering Department Graduate Student Seminar series is a bi-weekly seminar taking place during the Fall and Winter terms. Each seminar features a different student presenters.

Fall 2025 - Winter 2026: Seminars will be held from 12:30 pm - 1:30 pm every second Thursday. The location will be announced. *Please bring Student Card for attendance*

Speakers to Present in Winter 2026

Jan. 22, 2026, 12:30 pm

Location: ACEB 1415 

 

Presentation #1:  Synergistic Effects of Carbon Additives and Supercritical CO2 on Performance of Extruded Polystyrene Composite Foam

Presenter:  Apurv Gaidhani

Supervisor(s):   Dr. Paul Charpentier, Dr. Lauren Tribe

 Abstract:

Conventional polystyrene (PS) foams are widely used in insulation and packaging but are limited by low mechanical strength. This work explores the use of graphene nanoplatelets (GNP) and flaked graphite (FG) to improve the mechanical performance of PS foams produced using supercritical CO₂ (sc-CO₂) extrusion foaming. Foams were processed at two sc-CO₂ pressures (17.3 and 20.6 MPa) to evaluate the role of pressure on additive dispersion and mechanical behavior. Compression testing and dynamic mechanical analysis showed significant improvements in strength and stiffness at higher sc-CO₂ pressure, with compressive strength increases of up to 34% for GNP-filled foams and 66% for FG-filled foams. Micro-CT imaging revealed more uniform additive dispersion and well-defined closed-cell structures at elevated pressure, while finite element simulations closely matched experimental results. Overall, the study demonstrates that pressure-optimized sc-CO₂ foaming combined with carbon additives is an effective approach for producing lightweight PS foams with enhanced mechanical performance.

 

Presentation #2:  Progress towards knockout of glycerol dehydrogenase in Clostridium pasteurianum

Presenter:  Annika Tyszak

Supervisor(s):  Dr. Lars Rehmann

Committee member(s): Dr. Amarjeet Bassi, Dr. Arghya Paul

Abstract:

Clostridium pasteurianum, a strictly anaerobic gram-positive bacterium that has gained interest for utilization in biotechnological applications, has a complex metabolism. Its main products when grown on glycerol, a low-cost resource produced in large amounts by the biodiesel industry, as sole carbon and energy source include butanol, ethanol and 1,3-propanediol. The former are produced from an energy-generating (ATP-producing) path of the metabolic network, while the latter is produced from another disconnected path that serves the regeneration of redox equivalents in the form of NAD+. The first enzyme in the pathway from glycerol to butanol and ethanol is the glycerol dehydrogenase. A knockout of the gene for this enzyme should result in glycerol only being utilized for redox equivalent regeneration given the addition of a co-substrate like glucose for energy generation, and the inability of the organisms to grow on glycerol as the sole carbon and energy source.

A strain genetically modified in this fashion should allow for the creation of a process to use glycerol as carbon source for 1,3-propanediol production, while ensuring it will not be utilized elsewhere. Additionally, a knockout of this kind can help further the understanding of C. pasteurianum’s metabolism and redox potential regulation.

To knockout the glycerol dehydrogenase in C. pasteurianum CRISPR-Cas is supposed to be utilized in two different approaches harnessing heterologous and endogenous CRISPR-Cas machinery. A transformation protocol needs to be established based on a published high-efficiency electroporation protocol to transfer the required plasmids into C. pasteurianum. The current state of the work towards accomplishing the knockout and establishing a high-efficiency transformation will be presented.