Quartz Crystal Microbalances (QCM) in the context of paint coatings
Being able to predict when a coating will degrade is vital in achieving lower maintenance costs within industrial applications. A significant factor of degradation is the water retention of the coating, which results in the coating increasing in mass.
It would be of great value to have the ability to track mass along with the currently used electrochemical analysis methods. This research experience was used to investigate the viability of Quartz Crystal Microbalance (QCM) on measuring the mass changes of coatings using an Oscilloscope and a QCM balance device.
The use of an oscilloscope and waveform generator was first investigated using coatings of permanent marker and serial dilutions of commercial nail polish. It was found that this method was effective in creating macro-scale frequency responses of the quartz crystals (with identifiable peaks and sometimes 3rd / 5th harmonic overtones), however, had a frequency resolution of at most ± 31.3kHz leading to the conclusion that this method was unsuited for mass measurements.
The use of a QCM balance device was then investigated using a serial dilution of commercial nail polish. This produced precise resonant frequency values with a frequency resolution of approximately ± 1 Hz, along with the monitoring of overtone harmonic frequencies and energy dissipation over time. Using this instrument, the method was found to be suitable for monitoring coating mass uptake under certain limitations such as the viscosity of the coating, the thickness of the coating, and the mechanical properties of the crystals used. Although not within this investigation, the overtone data and energy dissipation has been found in previous studies to be useful in monitoring the mechanical properties of a substance. The analysis of these properties could be investigated in the future and may lead to the discovery of other key predictors of coating degradation.
Radical molecules in the gas phase are key intermediates in the formation of smoke from fire, smog from burning coal and other more natural changes in the upper atmosphere. These radical molecules are often very hard to study, as their extreme reactivity ensures that they react with other radical molecules at an almost instantaneous rate. Isolation of these radicals in very low concentrations using mass spectrometry is crucial for study to stop this self-reaction, and aids in understanding how they react with other molecules as well as their reaction rates. A mass spectrometer uses electro-spray ionisation (ESI) to attach a negative charge to a molecule, forming anions for detection. A 266nm UV laser targets the bond with iodine in these molecules in a process called photodissociation and severs the bond into a radical. However, as anions and radicals are both negatively charged, this caused some issues in detection due to electrical repulsion. Thus 3-iodoadamantane-1-carboxylic acid and its derivatives (3-(4-iodophenyl)adamantane-1-carboxylic acid, and 3-(4’-iodo-[1,1’-biphenyl]-4-yl]adamantane-1-carboxylic acid) were chosen as the increasing distance between the radical and the anion would allow for the study of the repulsive effects and how other molecules reacted with the radical due to proximity. 4-iodobenzoic acid was also chosen due to its shorter radical-anion distance to observe greater repulsive effects. The reaction rate of these pseudo first-order reactions was studied with regards to oxygen (O2), hydrogen-, deuterium- and chlorine-abstraction from chloroform (CHCl3), deuterochloroform (CDCl3) and tetrahydrofuran (THF). It was generally found that increasing the distance from the radical to the anion decreases the rate of reaction, a surprising outcome considering the reactivity of the radical in the effective vacuum of the mass spectrometer. It is currently thought that the anion almost balances the reactivity of the radical more as the distance increases.
Biofabrication and Tissue Morphology Group, Institute of Health and Biomedical Innovation, Queensland University of Technology
Microtia is a congenital condition affecting the development of the outer ear which occurs within approximately 1 to 5000 births. It is often associated with conductive hearing problems and significant psychological impact. Current aesthetic restoration of the ear can include the use of a prosthetic which is labour intensive, expensive and highly invasive for the patient. Three-dimensional (3D) technologies and advanced manufacturing could provide a faster, more economical and minimally invasive alternative to this traditional process. The aim of this study is to quantitatively compare scans taken on different smartphones to validate the low-cost multi-photogrammetry framework approach previously developed to enable the frugal capture of the external ear. A study including 10 adult participants without microtia was conducted with both ears being scanned using five devices. The smartphone photos were processed using the photogrammetry software Agisoft PhotoScan to create a 3D scan. The resulting scans were compared to a 3D model captured using a high-cost structured light scanner. The results of this study show that the smartphone-based photogrammetry method previously validated using the iPhone 7 and 8 can be translated to Android devices. However, it was also found that only the devices that had cameras compatible with the Android’s camera API (version 2) were able to produce an accurate model. The development of this low-cost, non-invasive 3D scanning framework enables the frugal modelling of the external ear for clinical application such as the creation of patient specific prostheses. Furthermore, the translation of this smartphone photogrammetry method across varying devices highlights the accessibility of this method to obtain accurate and reliable scans of the external ear.
Bone is a complex, dynamic tissue that is constantly undergoing bone remodelling - a process in which bone cells are simultaneously removing old bone (osteoclasts) and re-forming new bone (osteoblasts). Osteocytes (mechanosensing cells) play a fundamental role in this remodelling process. Osteocytes sense the mechanical loads and emit biochemical signals to regulate bone mass; thereby, bone formation occurs where bone tissue is overloaded and bone resorption occurs where bone tissue is underloaded. Underload may result from underactivity, as seen for example in patients confined to long-term bed rest and astronauts in space, or from excess bone mass. On the contrary, overload results from overactivity, as seen for example in the serving arm of tennis players, or from reduced bone mass. This mechanical regulation of bone is formalised in the “mechanostat” theory. The mechanostat theory compares a mechanical stimulus to a mechanical reference state, the setpoint; that is, bone gain occurs where the mechanical stimulus is greater than the setpoint (overload) and bone loss occurs where the mechanical stimulus is less than the setpoint (underload). Usually the setpoint is assumed to be a constant, independent of space and time. However, an issue with such a model is that there is the risk of resorbing too much bone along the neutral axis - the line of transition between tension and compression forces. In order to prevent such a problem, we investigated a new osteocyte-based mechanostat theory whereby the setpoint is constantly adapting with bone remodelling. The aim of this project is to utilise this new mechanostat theory, to investigate the evolution of the bone volume fraction (porosity) in a cross-section of a long bone, which is subject to changes in mechanical loading, and with an adapting setpoint. Mathematical and computational models are used to create numerical simulations that model the spatio-temporal evolution of this cross-section under disuse, that has an inhomogeneous distribution of bone volume fraction. These simulations are compared with the standard mechanostat theory, where the setpoint is a constant.
The overarching theme of this project was to develop a proof of concept for a autonomous racing vehicle using the Australian Centre for Robotic Vision's mini autonomous car ("Carlie"). This project specifically focused on developing cone detection and path planning algorithms to achieve this goal. The project was conceived in conjunction with QUT Motorsport, a prominent south-east Queensland racing team that is looking to expand their competitiveness by building an entry into the Formula Student Driverless competition. Algorithms were developed to detect cones and plan driveable paths within tracks formed by the cones. The accuracy of these algorithms was not measured as the only requirement of this project was to produce a working demonstration.
The result of the project was that "Carlie" was able to successfully navigate a track marked out by cones. This project shows that a QUT-developed autonomous racing vehicle is achievable and recommends that work should start on the development of a full-scale vehicle.
Many individuals with intellectual disabilities have Complex Communication Needs (CCN) and use Augmentative Alternative Communication (AAC) techniques and tools to express themselves. None of the current AAC methods offered on mobile devices, such as grid displays and visual scene displays, allow an individual to communicate independently with contextualised pictures. A Reflective Agile Iterative Design (RAID) framework has been adopted to co-design a mobile application which allows individuals with intellectual disabilities to communicate through the composition of pictures in a 2D space. An application using this technique may allow users with intellectual disabilities to independently communicate within a variety of environments, and with less cognitive processing than other existing AAC methods. An initial prototype was trialled through a series of communication workshops. Participants in these workshops all had intellectual disabilities and ranged in communicative abilities. Observations of the app’s usage were documented and used for directing design choices. With some aid from support workers, workshop participants could select multiple pictures of interest and use these to aid in communication. In the future, the longer-term usage of the app can be explored, as well as the addition of further features for image searching.
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QUT acknowledges the Traditional Owners of the lands where QUT now stands.