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Full-Text Articles in Engineering

Frequency Sensitive Mechanism In Low-Intensity Ultrasound Enhanced Bioeffects, April D. Miller, Abdoulkadri Chama, Tobias M. Louw, Anuradha Subramanian, Hendrik J. Viljoen Aug 2017

Frequency Sensitive Mechanism In Low-Intensity Ultrasound Enhanced Bioeffects, April D. Miller, Abdoulkadri Chama, Tobias M. Louw, Anuradha Subramanian, Hendrik J. Viljoen

Department of Chemical and Biomolecular Engineering: Faculty Publications

This study presents two novel theoretical models to elucidate frequency sensitive nuclear mechanisms in low-intensity ultrasound enhanced bioeffects. In contrast to the typical 1.5 MHz pulsed ultrasound regime, our group previously experimentally confirmed that ultrasound stimulation of anchored chondrocytes at resonant frequency maximized gene expression of load inducible genes which are regulatory markers for cellular response to external stimuli. However, ERK phosphorylation displayed no frequency dependency, suggesting that the biochemical mechanisms involved in enhanced gene expression is downstream of ERK phosphorylation. To elucidate such underlying mechanisms, this study presents a theoretical model of an anchored cell, representing an in vitro …


Use Of Natural Ores As Oxygen Carriers In Chemical Looping Combustion: A Review, Michael J. Matzen, Jessica Pinkerton, Xiaomeng Wang, Yaşar Demirel Jan 2017

Use Of Natural Ores As Oxygen Carriers In Chemical Looping Combustion: A Review, Michael J. Matzen, Jessica Pinkerton, Xiaomeng Wang, Yaşar Demirel

Department of Chemical and Biomolecular Engineering: Faculty Publications

Chemical looping combustion (CLC) has gained considerable ground in energy production due to its inherent carbon capture with a minimal energy penalty. The choice of metal oxide used as an oxygen carrier (OC) in CLC has a substantial weight on the overall efficiency of energy production as well as the ultimate cost per MW. While much work has gone into manufacturing synthetic OCs with high fuel conversions, harsh operating conditions and process limitations cause some unavoidable loss of the oxygen carrier. With low production costs and minimal conditioning required, natural ores have grown in interest as cheap alternative oxygen carriers. …


Theoretically Proposed Optimal Frequency For Ultrasound Induced Cartilage Restoration, April D. Miller, Anuradha Subramanian, Hendrik J. Viljoen Jan 2017

Theoretically Proposed Optimal Frequency For Ultrasound Induced Cartilage Restoration, April D. Miller, Anuradha Subramanian, Hendrik J. Viljoen

Department of Chemical and Biomolecular Engineering: Faculty Publications

Background: Matching the frequency of the driving force to that of the system’s natural frequency of vibration results in greater amplitude response. Thus we hypothesize that applying ultrasound at the chondrocyte’s resonant frequency will result in greater deformation than applying similar ultrasound power at a frequency outside of the resonant bandwidth. Based on this resonant hypothesis, our group previously confirmed theoretically and experimentally that ultrasound stimulation of suspended chondrocytes at resonance (5 MHz) maximized gene expression of load inducible genes. However, this study was based on suspended chondrocytes. The resonant frequency of a chondrocyte does not only depend on the …