The human body contains numerous orthopaedic tissues that are marked spatially gradients of mechanical properties, extracellular matrix composition, and cell phenotype. The bone-to-ligament transition, in particular, exhibits a sharp transition from a compliant fibrous tissue to a hard mineralized tissue that is critical for efficient load transmission without strain concentrations. However, such a transition is not necessarily recapitulated in surgical reconstruction of ruptured ligaments. Over the past decade, we have been interested in the micro-fiber topographies that are produced by the electrospinning process and their impact on the morphology and phenotype of adhesion-dependent mammalian cells. Initially, we began looking at whether these morphologies could be conducive to bone and ligament formation separately, and more recently we have endeavored to create electrospun materials that exhibit spatial gradients in micro-architecture, surface chemistry, and mechanical properties. This presentation will discuss fabrication methods to construct graded biomaterial scaffolds, their chemical and mechanical properties, and the in vitro culture of mesenchymal stem cells – that have the capacity to differentiate into various orthopaedic tissues – on these materials. Next, a strategy will be presented for processing these materials into large three-dimensional structures for ligament reconstruction. Finally, our ongoing efforts to incorporate biologically active factors within these electrospun materials will be described.

"Particle treatment processes are at the heart of both (surface) drinking water treatment and wastewater treatment. Many contaminants in water and wastewater are particles, are made into particles, or are removed by attaching to particles. Throughout my career, I have been pursuing the links between fundamental particle properties (particularly size distributions, but also shape, surface charge, and adsorbed materials such as natural organic matter) and the optimal design and operation of particle processes. Current work includes considering the fate of nanoparticles in conventional particle processes. Flocculation, precipitation, gravity removal processes (sedimentation, flotation, thickening), granular media filtration, and dewatering have all been the focus of my work with various Master’s and Ph.D. students. In addition, we have studied the linkages of these processes to one another in conventional water treatment plants. A few of the key insights from this work include the relative insignificance of the velocity gradient in determining the success of flocculation, the importance of flow patterns in open tanks such as flocculation and sedimentation reactors, the role of detachment in the effluent water quality from granular media filters, and a design methodology for granular media filters that could save piloting costs."

"Where our lab has historically focused on applied plant biotechnology, this seminar will describe the transition to a breadth of biotechnology projects that includes transplanting a hydrocarbon biosynthesis pathway from algae into a autotrophic organism that consumes H2, O2 and CO2 to produce biofuels. Our work in plant biotechnology has combined temporary immersion bioreactor systems with the delivery of embryogenic transcription factors using Agrobacterium auxotrophs toward the development of large scale plant propagation of species that are recalcitrant to somatic embryogensis (including chocolate tree). Our thin film algae bioreactors have achieved cell concentrations in excess of 20 grams per liter operating for months, and demonstrating that under light-limited conditions, algae growth is photon flux limited, and the advantage of using 'fast growing' algae is lost. Similarly, we show that for biofuel production using autotrophic growth, the energy use under non-growing conditions (maintenance energy) that is critically important for economic feasibility (not rapid growth). Our progress in genetic engineering the hydrocarbon synthesis pathway of the algae Botryococcus braunii into the autotrophic organism Rhodobacter capsulatus will be presented. Efforts to develop low-cost, low operating conditions bioreactors for biofuels will be presented along with progress on an 'engineered symbiosis' for cellulosic biofuels that combines cellulolytic capability of a obligate anaerobic organism protected by a yeast which produces fuel in exchange for oxidative protection under controlled oxygen transport rates. A few snapshots will be presented to illustrate the critical role of undergraduate research in supporting ongoing projects as well as developing new research ideas."