A Theoretical Model of a Molecular-Motor-Powered Pump

The motion of a cylindrical bead in a fluid contained within a two-dimensional channel is investigated using the boundary element method as a model of a biomolecular-motor-powered microfluidics pump. The novelty of the pump lies in the use of motor proteins (kinesin) to power the bead motion and the few moving parts comprising the pump. The performance and feasibility of this pump design is investigated using two model geometries: a straight channel, and a curved channel with two concentric circular walls. In the straight channel geometry, it is shown that increasing the bead radius relative to the channel width, increases the flow rate at the expense of increasing the force the kinesins must generate in order to move the bead. Pump efficiency is generally higher for larger bead radii, and larger beads can support higher imposed loads. In the circular channel geometry, it is shown that bead rotation modifies the force required to move the bead and that shifting the bead inward slightly reduces the required force. Bead rotation has a minimal effect on flow rate. Recirculation regions, which can develop between the bead and the channel walls, influence the stresses and force on the bead. These results suggest this pump design is feasible, and the kinesin molecules provide sufficient force to deliver pico- to atto- l/s flows.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44478/1/10544_2005_Article_6168.pd

Recommendations for the use of coronary and valve simulators in cardiac surgical training: A systematic review

OBJECTIVES: The aim of this study was to systematically review the simulators that are currently available for coronary artery bypass graft and valve surgery and, in addition, to review the validation evidence supporting them and to recommend several simulators for training based on the analysis of results. METHODS: A systematic literature search of the MEDLINE® (1946 to May 2021) and EMBASE® (1947 to May 2021) databases was performed to identify simulators for coronary artery and valvular procedures in cardiothoracic surgery. A selection of keywords and MeSH terms was used to execute the literature search. After identification of relevant articles, data were extracted and analysed. RESULTS: Thirty-seven simulators were found in 31 articles. Simulators were found for coronary artery bypass graft (n = 24) and valve surgery (n = 13). The majority of models were either benchtop (n = 28) or hybrid (n = 8) modalities. Evidence of validity was demonstrated in 15 (40.5%) simulators. Twenty-two (59.5%) simulators had no validation evidence, and 1 (2.7%) simulator had 3 or more elements of validity established. CONCLUSIONS: Two simulators were recommended for supplemental training in cardiothoracic surgery. Low-fidelity models can provide a broad foundation for surgical skills' development whereas high-fidelity simulators can be used for immersive training scenarios and appraisals. These should be utilized in early training, at which point the learning curve of trainees is steepest. © 2021 The Author(s). Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved