Abstract
Acoustic vibration can enhance bacterial biofilm formation
This article explores the use of low-frequency-low-amplitude acoustic vibration on biofilm formation. Biofilm development is thought to be governed by a diverse range of environmental signals, and much effort has gone into researching the effects of environmental factors including nutrient availability, pH and temperature on the growth of biofilms. Many biofilm-forming organisms have evolved to thrive in mechanically challenging environments, for example, soil, yet, the effects of the physical environment on biofilm formation have been largely ignored. Exposure of Pseudomonas aeruginosa to vibration at 100, 800 and 1600 Hz for 48 h resulted in a significant increase in the biofilm formation compared with the control, with the greatest growth seen at 800 Hz vibration. The results also show that this increase in biofilm formation is accompanied with an increase in the P. aeruginosa cell number. Acoustic vibration was also found to regulate the spatial distribution of biofilm formation in a frequency-dependent manner. Exposure of Staphylococcus aureus to acoustic vibration also resulted in enhanced biofilm formation with the greatest level of biofilm being formed following 48 h exposure at 1600 Hz. These results show that acoustic vibration can be used to control biofilm formation and therefore presents a novel and potentially cost-effective means to manipulate the development and yield of biofilms in a range of important industrial and medical processes.
For more information, follow the link: https://www.ncbi.nlm.nih.gov/pubmed/27338651
Novel numerical coupling techniques for aeroacoustic hybrid methodologies
Hybrid computational aeroacoustic methods are commonly used to numerically predict the far field propagation of aerodynamically generated sound. These methods separate the computation of the aerodynamically generated variables (such as the mean flow variables and the sources of sound) from the computation of the sound propagation. This research branch focuses on the implementation and validation of innovative coupling techniques between the aerodynamics computation and the acoustics propagation. In particular, the research focuses on the transfer of mean flow quantities to an acoustic solver and the coupling of aerodynamic noise sources, obtained from computational fluid dynamics (CFD) simulations, to an in-house solver for time domain acoustic propagation equations.
For more information, follow the link: https://www.mech.kuleuven.be/en/research/mod/research/aero-acoustics
Parallel stochastic noise reconstruction methods
To simulate the noise in flow acoustics, one needs dyna-mic computational fluid dynamics (CFD) data input. This will help to generate the sources during the whole simulation period. But gaining this dynamic data is a challenge: the classical CFD methods are too expensive to use; moreover, if they are not performed ‘on-fly’ and immediately integrated into aeroacoustic solver, then one needs enormously large storage. Stochastic methods are developed to reconstruct unsteady CFD data from steady solutions, such as Reynolds-averaged Navier–Stokes (RANS). Our group develops and extends a random particle method for this purpose. Three-dimensional (3D) parallel implementation insures computationally fast and statistically accurate solutions based on Gaussian, Liempann and Von Karman CFD energy spectra.
For more information, follow the link: https://www.mech.kuleuven.be/en/research/mod/research/aero-acoustics
Using bubbles to transform medicine, develop ultrasonic cleaning and learn more about whales and dolphins
Pioneering research into bubble acoustics is developing exciting applications in several fields. Professor Tim Leighton and colleagues in the Institute of Sound and Vibration Research (ISVR) are discovering new ways of understanding the oceans, delivering drugs and medical procedures and even making cleaning systems work more efficiently.
For more information, follow the link: https://www.southampton.ac.uk/engineering/research/impact/bubble_acoustics.page
Newborn hearing screening
If deafness can be diagnosed at birth, then the child can get educational support or hearing aids to help his or her development. Research at the University of Southampton’s Institute of Sound and Vibration Research (ISVR) helped to develop and evaluate a pioneering test that enables deafness to be detected in newborn babies. Since it has been adopted by the National Health Service, all newborn babies in the United Kingdom are routinely screened. The research at ISVR has contributed to the World Health Organization’s recommendations in favour of universal newborn hearing screening.
For more information, follow the link: https://www.southampton.ac.uk/engineering/research/impact/newborn_hearing_screening.page
Leading the way in aircraft noise reduction
Research at the University of Southampton’s Airbus Noise Technology Centre (ANTC) and the Rolls-Royce University Technology Centre (UTC) in gas turbine noise has given Airbus and Rolls-Royce tools to understand, predict and reduce noise pollution from commercial aircraft. This will help them make sure they are on track to meet the European Union’s stringent noise reduction targets and maintain their competitive edge. This is also good news for the millions of people who live near our busiest airports.
For more information, follow the link: https://www.southampton.ac.uk/engineering/research/impact/leading_the_way_in_aircraft_noise_reduction.page
Ultrasonic particle manipulation
When small particles such as human cells or bacteria are placed in an ultrasonic sound field, they experience a force that can be used to move them around.
By carefully controlling that field, it is possible to manipulate thousands of cells at once, creating an acoustic tweezers (or ‘sonotweezers’). This ability to precisely position such tiny objects opens up many exciting applications that would be difficult using other technologies such as optical tweezers that can only manipulate a much smaller number of particles simultaneously.
For more information, follow the link: https://www.southampton.ac.uk/engineering/about/staff/pgj1a06.page
Human response to vibration in residential environments
The aim of the Defra-funded project NANR209 ‘Human response to vibration in residential environments’ was to develop exposure–response relationships for vibration experienced in residential environments from sources outside of the residents’ control. The project was performed at the University of Salford between January 2008 and March 2011. The final report was published on the Defra website on 6 September 2012. The NANR209 Final Report consists of the following documents: Executive summary; Final project report; Technical report 1: Measurement of vibration exposure; Technical report 2: Measurement of response; Technical report 3: Calculation of vibration exposure; Technical report 4: Measurement and calculation of noise exposure; Technical report 5: Analysis of the social survey findings; and Technical report 6: Determination of exposure-response relationships. This document is the Executive summary.
For more information, follow the link: http://usir.salford.ac.uk/23347/