The growth of biofilms changes the hydrodynamics of porous media, which will influence the transport of bacteria and contaminants in natural and engineered systems. Traditionally, biofilms have been modeled as an impermeable domain in porous media, such that no water can enter biofilms and contaminants can only enter biofilms via molecular diffusion. Such a modeling approach is based on the assumption that the permeability of biofilms is the same as that of Extracellular Polymeric Substances (EPS), which are considered to have very low permeability. In this study, we investigate the impacts of biofilm properties on water flow using microfluidic device experiments and pore-scale modeling. E. coli biofilm was established inside a microfluidic channel packed with unisized glass beads in a single layer. A 5*5 mm2 area was live-stained and imaged via confocal microscopy at three different growth stages to represent three biofilm levels in the system. After image analysis using FIJI and AutoCAD software, the flow in the bio-clogged porous media was simulated using COMSOL Multiphysics. In these simulations, biofilm was modeled as a separate permeable domain in porous media instead of an impermeable domain. A Forchheimer-corrected version of the Brinkman equations was applied to simulate the flow in the porous biofilm regions. Two properties of biofilms, namely biofilm porosity (BPO) and biofilm permeability (BPE), were altered to examine their effects on the permeability of the system. It was found that different values of BPO and BPE clearly affect the flow paths, velocity patterns, and permeability of the system. Considering biofilms as impermeable results in significant underestimations of the flow properties. In addition, two simplified modeling scenarios, namely uniform coating and symmetric contact filling, were investigated for a possible abridging in the arduous modeling procedure of the real biofilm geometry.

Generation Z (Gen-Z) is composed of those born in the late 1990’s or after. The first cohorts of Gen-Z students gradually started to enter colleges after 2013. Gen-Z students are very different than millennials in almost all aspects. They are more likely to reject the traditional and conventional teaching methods that lack active learning components. A shift towards modern and interactive student-centered methods is being implemented by a new generation of instructors to better serve Gen-Z needs. However, this transition from passive lecture-based instruction to active learning methods is hindered by a gap that we call “the missing step”. This missing step in the transition phase refers to training and preparing future faculty to adopt research-based instructional strategies. My fellow aspiring professors and I were mostly educated via old-school methods. Without proper training on STEM teaching, we were likely to approach our teaching by modeling what we saw. If granted the opportunity to teach engineering in a faculty role, we would have come into it lacking teaching theory and instructional strategies rooted in engineering education. If a new instructor is not familiar with subjects such as “active learning”, “backward design”, “evidence-based instructional strategies”, “flipped classroom”, and “Bloom’s revised taxonomy”, or is not acquainted with importance of modern classroom assessment techniques, rubrics, and motivation strategies, the result will be an unfillable gap between the instructor and the Gen-Z students. I was in the first cohort of Ph.D. students who completed the College of Engineering’s graduate teaching fellowship program at the University of Nebraska-Lincoln. This one-year, well-structured, peer-observation program gave me invaluable knowledge about teaching following the research, helped me in designing a course in Canvas system, taught me how to write my teaching philosophy properly, and prepared me to achieve the CIRTL associate status. Starting such a program in every school for interested graduate students can make a significant difference. I will present my perspectives on the program and its impact.