Stress relaxation in epithelial monolayers is controlled by the actomyosin cortex

Epithelial monolayers are one-cell thick tissue sheets that separate internal and external environments. As part of their function, they have to withstand extrinsic mechanical stresses applied at high strain rates. However, little is known about how monolayers respond to mechanical deformations. Here, by subjecting suspended epithelial monolayers to stretch, we find that they dissipate stresses on a minute time-scale in a process that involves an increase in monolayer length, pointing to active remodelling of cell architecture during relaxation. Strikingly, monolayers consisting of tens of thousands of cells relax stress with similar dynamics to single rounded cells and both respond similarly to perturbations of actomyosin. By contrast, cell-cell junctional complexes and intermediate filaments do not relax tissue stress, but form stable connections between cells, allowing monolayers to behave rheologically as single cells. Taken together our data show that actomyosin dynamics governs the rheological properties of epithelial monolayers, dissipating applied stresses, and enabling changes in monolayer length.Peer ReviewedPostprint (published version

Audio-visual-olfactory resource allocation for tri-modal virtual environments

© 2019 IEEE. Virtual Environments (VEs) provide the opportunity to simulate a wide range of applications, from training to entertainment, in a safe and controlled manner. For applications which require realistic representations of real world environments, the VEs need to provide multiple, physically accurate sensory stimuli. However, simulating all the senses that comprise the human sensory system (HSS) is a task that requires significant computational resources. Since it is intractable to deliver all senses at the highest quality, we propose a resource distribution scheme in order to achieve an optimal perceptual experience within the given computational budgets. This paper investigates resource balancing for multi-modal scenarios composed of aural, visual and olfactory stimuli. Three experimental studies were conducted. The first experiment identified perceptual boundaries for olfactory computation. In the second experiment, participants (N=25) were asked, across a fixed number of budgets (M=5), to identify what they perceived to be the best visual, acoustic and olfactory stimulus quality for a given computational budget. Results demonstrate that participants tend to prioritize visual quality compared to other sensory stimuli. However, as the budget size is increased, users prefer a balanced distribution of resources with an increased preference for having smell impulses in the VE. Based on the collected data, a quality prediction model is proposed and its accuracy is validated against previously unused budgets and an untested scenario in a third and final experiment

A Calibrated Olfactory Display for High Fidelity Virtual Environments

Olfactory displays provide a means to reproduce olfactory stimuli for use in virtual environments. Many of the designs produced by researchers, strive to provide stimuli quickly to users and focus on improving usability and portability, yet concentrate less on providing high levels of accuracy to improve the fidelity of odour delivery. This paper provides the guidance to build a reproducible and low cost olfactory display which is able to provide odours to users in a virtual environment at accurate concentration levels that are typical in everyday interactions; this includes ranges of concentration below parts per million and into parts per billion. This paper investigates build concerns of the olfactometer and its proper calibration in order to ensure concentration accuracy of the device. An analysis is provided on the recovery rates of a specific compound after excitation. This analysis provides insight into how this result can be generalisable to the recovery rates of any volatile organic compound, given knowledge of the specific vapour pressure of the compound

Visuohaptic augmented feedback for enhancing motor skills acquisition

Serious games are accepted as an effective approach to deliver augmented feedback in motor (re-) learning processes. The multi-modal nature of the conventional computer games (e.g. audiovisual representation) plus the ability to interact via haptic-enabled inputs provides a more immersive experience. Thus, particular disciplines such as medical education in which frequent hands on rehearsals play a key role in learning core motor skills (e.g. physical palpations) may benefit from this technique. Challenges such as the impracticality of verbalising palpation experience by tutors and ethical considerations may prevent the medical students from correctly learning core palpation skills. This work presents a new data glove, built from off-the-shelf components which captures pressure sensitivity designed to provide feedback for palpation tasks. In this work the data glove is used to control a serious game adapted from the infinite runner genre to improve motor skill acquisition. A comparative evaluation on usability and effectiveness of the method using multimodal visualisations, as part of a larger study to enhance pressure sensitivity, is presented. Thirty participants divided into a game-playing group (n = 15) and a control group (n = 15) were invited to perform a simple palpation task. The game-playing group significantly outperformed the control group in which abstract visualisation of force was provided to the users in a blind-folded transfer test. The game-based training approach was positively described by the game-playing group as enjoyable and engaging

New crown ether-based ionic liquids as a green and versatile organocatalyst for three-component synthesis of 1,5-dihydropyrano2,3-cchromene derivatives

A simple and green method for the synthesis of 1,5-dihydropyrano2,3-cchromene derivatives has been reported by three-component reaction of aromatic aldehydes, malononitrile, and 3-hydroxycoumarin in the presence of a series of novel crown ether-based ionic liquids (CE-based ILs) in H2O/EtOH (1:1), under the reflux conditions. The novel CE-based ILs have been synthesized by 18-crown-6 or dibenzo 18-crown-6 chelated with sodium benzenesulfinate derivatives and used as a green and environmental organocatalyst. This method has some advantages such as the aqueous reaction medium, stable catalysts, cleaner reaction profiles and high yield of products in short reaction time. © 2020 Bentham Science Publishers

Effect of Iron Oxide Nanoparticles for the Removal of Coliform Bacteria from Contaminated Water

BACKGROUND AND OBJECTIVE: Iron oxide nanoparticles at low concentrations can act as a source of iron ions required microorganisms but high concentrations can cause stress and cell damage in bacterial cells are reduced cell growth. The effect of iron oxide nanoparticles were studied remove coliform bacteria from contaminated water. METHODS: In this experimental-laboratory study synthetic municipal wastewater by adding 5 mL to 60 liters of water in urban distribution network was built. Every time in half a liter of synthetic samples 100, 250, 500, 1000, 2000, 4000 and 6000 ppm of iron oxide nanoparticles were added at the time of zero, 20, 40, 60, 80 and 100 minute samples and with method 15-tube was tested. FINDINGS: With increasing concentrations of iron oxide nanoparticles from 100 ppm to 6000 ppm the most likely number of coliforms per 100 ml (MPN) average removal rate from 70 percent to 82 percent synthesized samples. (Number of MPN) and removal efficiency at 0, 20, 40, 60, 80 and 100 minutes, was (660.52) 0% (330.42) 48.83, (317.00) 53.75, (200.14) 68.48, (161.66) 73.96 and (128.04) 80.16 respectively. Significant differences between time and removal of coliform bacteria (P=000.0) was observed. Maximum efficiency in the contact time of 100 minutes and 6000 mg/L concentration of iron oxide nanoparticles to 100 percent. CONCLUSION: The results showed that with increasing contact time and increasing concentrations of nanoparticles, remove the MPN samples is increasing