Tracie Barber | Searcharxiv

arXiv2026

A Modular 3D-Printed Design to Investigate Prebiotic Chemical Systems in Hot Spring Pools

The emergence of membranous compartments (protocells) with encapsulated genetic material was a crucial step life's origin and evolution. The hot spring hypothesis for the origin of life suggests that protocells could have formed in hot spring pools and encapsulated organic matter. Previous investigations have focused on mimicking wet-dry (WD) cycles within a single pool, which precludes simulation of many hydrothermal field conditions, such as differential mineralogy, variable temperature and pH and water flow between multiple hot spring pools. Here, we present a modular 3D-printed hydrothermal field simulator that mimics the complex nature of hot spring fields by controlling the variability of a series of linked pools, including WD cycles, temperature, pH, mineralogy, and mixing of different fluids. Results from using the prototype hot spring field design demonstrate the ability to spontaneously form lipid vesicles that encapsulate organic matter within membranous compartments comprised of decanoic acid:decanol (4:1) or the phospholipids POPC:POPG (1:1). We observed distinct morphological differences in the vesicles, ranging from thick-walled multilamellar, thin-walled oligolamellar and unilamellar as well as giant unilamellar vesicles formed under multiple WD cycles in the simulator pools. Cargo encapsulation was favoured in the cell-like giant unilamellar and small oligolamellar vesicles. Overall, hot-spring simulator offers a customisable avenue for studying other hot spring processes such as prebiotic chemical reactions, mineral surface catalysis, and the complexity of hydrothermal field dynamics.

cond-mat.soft↗

arXiv2022

Mitigation of the Turbulence within an Arteriovenous Fistula with a Stent Implantation

The transitional flow which initiates within the junction (anastomosis) of an arteriovenous fistula (AVF) is known to be a contributing factor in the onset of vascular disease. A novel treatment method involving the implantation of a flexible stent across the anastomosis has enabled the retention of a large proportion of functioning AVFs, despite the propensity for stent malapposition to occur at the sharp inner curve of the anastomosis. Large Eddy Simulations (LES) of a patient-specific AVF with and without the presence of a stent captured oscillatory flow behaviour emanating from the interface of the two inlet flows in the stent-absent case, however, these oscillatory features were subdued in the stented case. The stent-absent case generally had higher Turbulent Kinetic Energy (TKE) in the anastomosis which led to larger cycle-to-cycle variations in wall shear stress (WSS). The significantly lower TKE generated at the heel of the stented AVF was contained within the malapposed stent, thereby resulting in lower WSS fluctuations. However, a slight increase in turbulence downstream of the malapposed stent edge was noted. This detailed study reveals a significant decrease in turbulence within the AVF in the presence of the stent, thereby, providing a level of understanding underpinning the success of the treatment strategy from a fluid dynamic perspective.

physics.flu-dyn↗