Sonic cracking at low acoustic amplitudes by Nicole Anderton, Craig S. Carlson, Naoyuki Otake, Hu Xinyue, Momoka Yamasaku, Nobuki Kudo, and Michiel Postema was published in the Proceedings of the 44th Symposium on UltraSonic Electronics in 2023.
Sonic cracking is a term used for the ultrasound-assisted release of gas from rigid shell-encapsulated microbubbles. Based on high-speed footage, it has been speculated that tiny flaws in the shell may contribute towards sonic cracking. The purpose of this study was to evaluate this hypothesis by subjecting albumin-encapsulated microbubbles to simultaneous ultrasound and high-speed photography to trigger sonic cracking and collect qualitative evidence of any shell defects. Although some highspeed photography footage showed release from microbubble with apparent flaws, gas release from apparently intact bubbles was also observed. Therefore, the hypothesis that sonic cracking of ultrasound contrast agent microbubbles is associated with the pre-existence of such flaws in the microbubble shells has not been confirmed.
This study was a collaborative work of Tampere University, the University of the Witwatersrand, Johannesburg, and Hokkaido University.
Diameter as a function of time, simulated for a free gas bubble of initial diameter 3.5 μm (a) and selected video frames (b), whose timestamps are indicated in red, green, blue, cyan, and black, respectively. A cup-shaped fragment is circled in magenta (c).
Ultrasonic nucleation of bioactive glass particles by Michiel Postema, Craig S. Carlson, Nicole Anderton, Hu Xinyue, Momoka Yamasaku, Laeticia Petit, Jonathan Massera, and Nobuki Kudo was published in the Proceedings of the 44th Symposium on UltraSonic Electronics in 2023.
Bioactive glass, such as 13-93B20, is a class of biomaterials, generally used in bone regeneration. Despite its density of 2.60 g cm-3 at room temperature, small but not negligible quantities of 13-93B20 have been observed to float in aqueous media, rather than to sink. It has been hypothesised that microscopic gas bubbles entrapped in the particles are causing this undesired feature. The purpose of this study was to evaluate this hypothesis by subjecting 13-93B20 particles to ultrasound to trigger a release mechanism and to quantify any effects thereof. Nucleation was observed from bioactive glass under sonication. The highspeed photography footage strengthens the hypothesis that some bioactive glass particles contained gas that was released owing to sonication.
This study was a collaborative work of Tampere University, the University of the Witwatersrand, Johannesburg, and Hokkaido University.
Selected frames before (a), during (b–e), and after sonication (f). Timestamps have been added to the lower right corners. Exposure times were 100ns per frame. Each frame corresponded to a 100×100-μm2 area.
Rough handling accelerates tablet swelling in ultrasound by Craig S. Carlson, Michiel Postema, Nicole Anderton, Markus Hannula, Joona Sorjonen, Hu Xinyue, Naoyuki Otake, Nobuki Kudo, Jari Hyttinen, and Jarkko Ketolainen was published in the Proceedings of the 44th Symposium on UltraSonic Electronics in 2023.
Oral pharmaceutical tablets are typically swallowed in whole, after which slow disintegration in the stomach facilitates steady drug released. Previously, high-speed footage had revealed ultrasonic nucleation of microscopic gas pockets inside analgesia tablet fragments. The presence of these microscopic pockets has been speculated to be the cause of accelerated disintegration under sonication. One might wonder, whether rough handling of tablets causes internal damage, which in turn could change the disintegration times. The purpose of this study was to quantify the influence of rough tablet handling on the swelling rate of tablets comprising hydrophobic tablet matrix only. Our reuslts showed swelling rates of tablets that had undergone rough handling were higher than those of identical unhampered tablets. This study was a collaborative work of Tampere University, the University of the Witwatersrand, Johannesburg, Hokkaido University, and the University of Eastern Finland.
Schematic drawing of the experimental setup for rough tablet handling, comprising a pipe of 22-mm bore diameter (a) with a nut release mechanism at 82-cm height (b), fixated on a wooden frame (c), with the pipe exiting above a tablet sandwiched between two 1-SHP coins (d) impacted by the nut (e), and a high-speed camera at a 30-cm horizontal distance (f). The inlay frame was captured during nut impact. The line density of the mesh corresponds to 1/mm.
Micro-computed tomography shows silent bubbles in squeaky mozzarella by Elina Nurkkala, Markus Hannula, Craig S. Carlson, Anu Hopia, Jari Hyttinen, and Michiel Postema was published in the 9th volume of Current Directions in Biomedical Engineering in 2023.
Cheese may have a resonating internal structure in the audible spectrum. It has been speculated that this structure or small bubbles that are formed as a result of fermentation are responsible for creating audible acoustic responses. The purpose of this study was to design a mechanical methodology to create audible acoustics from cheese samples and to quantify bubble presence in a sample. Our results confirm the presence of small bubbles in squeaky mozzarella, but these generate frequencies much higher than those recorded.
This study was a collaborative work of Tampere University, the University of the Witwatersrand, Johannesburg, and the University of Turku.
Normalised audio signal as a function of time of a single mozzarella squeak (a) and the Fourier amplitude spectrum thereof (b). Controls are represented by red lines.
Quantification of carbon black tattoo ink hydrophobicity pre- and post-sonication by Jean de Bruin Jordaan, Michiel Postema, Craig S. Carlson, and Ken J. Nixon was published in the 9th volume of Current Directions in Biomedical Engineering in 2023.
According to early studies, ultrasound might change the hydrophobicity of microparticles. The purpose of this study was to confirm or refute the presence of hydrophobic components in carbon black tattoo ink and to relate sonication to such presence. Carbon black tattoo ink was found to be very hydrophobic. However, sonication was found to make the dispersion less hydrophobic. Influencing the hydrophobicity of tattoo ink might change the permanence of a skin tattoo.
This study was a collaborative work of the University of the Witwatersrand, Johannesburg, and Tampere University.
Intensity partition coefficients of carbon black tattoo ink as a function of pre-applied ultrasound pressure amplitude. Coefficients have been represented on a logarithmic scale. Cropped frontal photograph of a representative experiment overlain.
Sobel edge detection for quantifying the effectiveness of focused ultrasound thalamotomy for tremor relief by Vered Aharonson, Michiel Postema, Robyn Gebbie, Jesse Van Der Merwe, and Ilana Schlesinger was published in the 9th volume of Current Directions in Biomedical Engineering in 2023.
Focused ultrasound on the thalamus is employed to relieve tremor in movement disorders. The treatment efficacy is currently assessed by subjective observation of patient tremor during hand movements. In this study we developed a computational method that rapidly computed tremor severity estimate in an explainable and clinically useful manner from a traditional pen-and-paper spiral drawing. This rapid quantitative and objective tremor assessment can easily be implemented during focused ultrasound treatment and replace the subjective assessment currently employed.
This study was a collaborative work of the University of the Witwatersrand, Johannesburg, the University of Nicosia, Rambam Medical Center, and Tampere University.
Processed treated-hand spiral drawing of a patient before treatment (a), one week after treatment (b), one month after treatment (c), three months after treatment (d), six months after treatment (e), and twelve months after treatment (f).
High-speed optical observations of asymmetric pulsations of microbubbles released from tablet matrix by Nicole Anderton, Craig S. Carlson, Hu Xinyue, Naoyuki Otake, Joona Sorjonen, Nobuki Kudo, Jarkko Ketolainen, and Michiel Postema was published in the 9th volume of Current Directions in Biomedical Engineering in 2023.
Microbubbles with a negligible shell are of utmost importance in the study of harmonic ultrasound contrast agents. The purpose of this study was to collect and quantify experimental pulsation footage of gas microbubbles released from tablet matrix under sonication. This feasibility study confirmed that the gas microbubbles released from tablet matrix may pulsate asymmetrically. Thus, they might be suitable tracers for harmonic imaging.
This study was a collaborative work of Tampere University, the University of the Witwatersrand, Johannesburg, Hokkaido University, and the University of Eastern Finland.
Radius as a function of time of a microbubble of 5.7-μm pre-sonication resting radius, and selected high-speed footage overlain. The overlain frames correspond to 20-μm diameters. The microbubble captured during contraction (green) showed buckling.
Sonic cracking of calcium carbonate-encapsulated microbubbles observed at moderate acoustic amplitudes by Albert T. Poortinga, Michiel Postema, Craig S. Carlson, Nicole Anderton, Momoka Yamasaku, Naoyuki Otake, and Nobuki Kudo was published in the 9th volume of Current Directions in Biomedical Engineering in 2023.
Theranostic agents are materials that act both as tracers during diagnostic imaging and as vehicles carrying and releasing therapeutics during treatment. The purpose of this study was to investigate the suitability for theranostic applications of a novel microbubble agent with thick shells composed of calcium carbonate. We observed pulsations but no gas release at a 0.1-MPa amplitude and intra-encapsulation fragmentation during sonication at a 0.3-MPa amplitude. At 0.5-MPa amplitude sonication, release was observed from more than 70% of the microbubbles in the field of view. This finding indicates that the microbubbles were stable scatterers during 0.1-MPa sonication, but instable vehicles during 0.5-MPa sonication. The pressures used in this study to observe release were too low to allow for unwanted inertial cavitation. In conclusion, therefore, the microbubbles studied were a promising theranostic agent whose contents could be released at moderate acoustic amplitudes.
This study was a collaborative work of Eindhoven University of Technology, Tampere University, the University of the Witwatersrand, Johannesburg, and Hokkaido University.
High-speed footage of typical dynamic microbubble behaviour at different acoustic amplitudes: pulsation at a peak-negative pressure of 0.1MPa (a), unsuccessful release at 0.1MPa (b), intra-encapsulation fragmentation at 0.3MPa (c), coalescence at 0.3MPa (d), and successful gas release at 0.5MPa (e). Each circular photo frame corresponds to a 15-μm diameter.
First experiments with carbon black pigment dispersion acting as a Janus ultrasound contrast agent by Jean de Bruin Jordaan, Ken J. Nixon, Craig S. Carlson, and Michiel Postema was published in the 4th volume of BIO Integration in 2023.
The development of theranostic ultrasound contrast agents has been of major interest, especially since the introduction of novel nanomedicines. Such agents cannot be traced after destructive release. Acoustic Janus particles might be used as ultrasound contrast agents as well as drug-delivery tracers. Our finding that submicron carbon black particles have acoustic Janus properties makes them interesting candidates for long-lasting ultrasound contrast agents in theranostics.
This study was a collaborative work of the University of the Witwatersrand, Johannesburg, and Tampere University.
Schematic line drawing of the photography part of the experimental setup, composed of a light source (A) that generated rays of light (B) of intensity I0; that scattered off a white background (C), passed through a cuvette of thickness x (D) containing n-octanol (E) and distilled water (F), exited the cuvette with intensity I(x), and were projected onto the complementary metal-oxide semiconductor of a webcam (G) and converted to a grayscale matrix of intensity values Iij.
Closeups of a not-so-domestic mite tritonymph by Rustem Uzbekov, Ayache Bouakaz, and Michiel Postema was published in the Allergo Journal International in 2023.
In response to a recent mini-review on the biology of house dust mites and storage mites, the authors wondered about the potential fauna present in their imaging facilities. As opposed to biolabs and chemical labs, imaging facilities contain a wealth of dust. Not only are cleaning rules for such facilities less strict, most, if not all, physicists prefer that cleaning staff do not touch any equipment at these facilities. The purpose of this study was to literally zoom in on a dust flake that had fallen onto a preparation slide.
This study was a collaborative work of the University of Tours, LE STUDIUM Loire Valley Institute for Advanced Studies, Tampere University, and the University of the Witwatersrand, Johannesburg.
Closeup of the head of a mite tritonymph.
超声医学原理by Michiel Postema, Spiros Kotopoulis, and Klaus-Vitold Jenderka was published by European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) in 2023.
This book chapter is the Chinese translation of Physical Principles of Medical Ultrasound, which is included in the EFSUMB Course Book, 2nd edition, edited by Christopher F. Dietrich.
This chapter contribution was a collaborative work of the University of the Witwatersrand, Johannesburg, the University of Tours, LE STUDIUM Loire Valley Institute for Advanced Studies, Haukeland University Hospital, and the Merseburg University of Applied Sciences.
Snippet of the cover page of the Chinese translation of Physical Principles of Medical Ultrasound.
A pocket-sized recipe for cooking up a scientific manuscript by Craig S. Carlson and Michiel Postema was published by Tampere University in 2023.
This booklet is intended to be read from cover to cover, in the order of writing. It is not so much a general guideline as a proven recipe to get your scientific manuscript accepted by a peer-reviewed journal. We do not differentiate between high-impact peer-reviewed journals and low-impact national conference proceedings. The principle of writing is the same. The recipe works for both.
When using any other recipe for cooking, you are going to use it only a couple of times. After that, you are going to adjust the recipe to match your flavour. This recipe is intended for the same purpose. Follow it get get your first papers and your thesis accepted. After that, start changing it so that you can produce manuscripts about which you feel more comfortable.
Front and rear cover of the booklet.
Sonic disruption of wood pulp fibres aided by hydrophobic cavitation nuclei by Nicole Anderton, Craig S. Carlson, Albert T. Poortinga, Hu Xinyue, Nobuki Kudo, and Michiel Postema was published in the 62nd volume of the Japanese Journal of Applied Physics in 2023.
For paper manufacturing and biofuel production, the controlled deformation of wood pulp is of interest, provided that the integrity of the fibre structure remains intact. Conventional ultrasonic pretreatment in the near-audible range has been observed to cause uncontrolled inertial cavitation damage in wood pulp fibres. To prevent internal damage, we proposed to subject wood pulp mixed with hydrophobic particles to 1-MHz short pulses above the nucleation threshold of the particles but below the Blake threshold, and to observe the interaction of pulsating cavities and wood pulp fibres assisted by high-speed photography.
This study was a collaborative work of Tampere University, the University of the Witwatersrand, Johannesburg, Eindhoven University of Technology, and Hokkaido University.
Radial response (a) of a hydrophobic core subjected to a pressure pulse (b), measured from high-speed video footage. Selected high-speed footage (c) with schematics overlain show a bubble at its maximum (i), its collapse to form a liquid jet (ii), and a composite image of both frames (iii).
