UV-induced wettability change of teflon-modified ZnO nanorod arrays on LiNbO3 substrate

Aligned ZnO nanorod arrays films were grown on LiNbO3 substrates by aqueous growth, and subsequently rendered superhydrophobic with RF sputtered coated Teflon. The as-prepared surface exhibits superhydrophobicity with a water contact angle (CA) of 154.5deg. After 2 hours of UV irradiation on the surface, the surface wettability was approaching hydrophilic state; CA was measured to be 113deg. This study provides insights into the methodology of a low cost, efficient technique that has great potential for preparing nanostructured surface with tunable wettability

Aqueous synthesis and computational modelling of metal oxide nanostructures for gas sensing applications

In this thesis, the author pursued a holistic, multi-faceted approach to the development of ZnO, WO3 and WO3•nH2O nanostructures grown from aqueous chemical techniques, and their application to nitrogen dioxide (NO2) and hydrogen (H2) gas sensing; and understanding the adsorption processes of nitrogen oxides (NOx) on ZnO nanomaterials with Density Functional Theory (DFT). Several new deposition techniques were developed for the fabrication of corrugated ZnO nanorods and interconnected ZnO nanowires. The choice of seed/nucleation layer used during ZnO deposition was investigated by the author, and was identified to be a major variable in the resultant nanostructured morphology. The use of hemispherically terminated seed/nucleation layers resulted in arrays of nanorods emanating perpendicularly from the plane of the substrate. Interestingly, rougher polygonal seed/nucleation layers were found to facilitate the growth of an interconnected nanostructured morphology. A search of current literature revealed that many nanostructured WO3 deposition techniques required the use of expensive, dangerous and/or exotic reagents. Considering this, the author pursued the development of an aqueous deposition method capable of forming a nanostructured thin film via inexpensive and relatively innocuous chemical precursors. This led to the development of two new methods: the first being a successive ionic layer adsorption reaction; and the second, a sol-gel method. For the sol-gel method, it was found that the humidity of the atmosphere in which the samples were dried had a significant impact on both the nanostructured morphology and the crystallography of the resultant nanostructures. Using the developed deposition techniques, conductometric gas sensors based on nanostructured ZnO and WO3 were fabricated, and evaluated towards H2 and NO2. ZnO nanorod arrays demonstrated the highest sensitivity of the developed sensors towards NO2. Reducing the dimensions of the ZnO nanomaterial further, to an interconnected nanowire array, made it possible to reduce the operational temperature of the sensor by almost 60%, with only a marginal decrease in sensitivity. Optical gasochromic H2 sensors based on Pt/WO3 thin films exhibited excellent baseline stability, and the low operational temperature of 100 °C, showing promise for remote sensing applications. All concentration ranges investigated were below the lower explosive threshold of H2, and below NO2 concentrations that cause negative physiological effects in healthy adults. The author used DFT to investigate gas interactions of NOx molecules and its dissociation products with the ZnO(2ĪĪ0) surface, at the atomic scale. Charge transfer between the surface and adsorbate was found to occur, regardless of the strength of adsorption. The direction of the charge transfer was in good agreement with experimentally observed sensor resistance changes during exposure to NO2. The calculated binding energies of atomic N and O onto the ZnO(2ĪĪ0) surface were indicative of chemisorption. It was found that NO and NO2 preferentially physisorbed onto ZnO(2ĪĪ0), over one or more surface zinc atoms, with minimal changes to the surface geometry. On oxygen defect containing ZnO(2ĪĪ0) surfaces, NO2 typically chemisorbed onto two or more defect site zinc atoms, leading to significant surface reconstruction. Comparisons between experimental and theoretical observations were made whenever possible

Performance and Radiation Testing of a Low-Noise Switched Capacitor Array for the CMS Endcap Muon System.

The 16-channel, 96-cell per channel switched capacitor array ( SCA) ASIC developed at UC Davis for the cathode readout of the cathode strip chambers ( CSC) in the CMS endcap muon system is ready for production. For the final full-sized prototype, the Address Decoder was re-designed and LVDS receivers were incorporated into the chip package. Under precision testing, the chip exhibits excellent linearity within the 1V design range and very low cell-to-cell pedestal variation. Monitored samples of the production design were subjected to exposure to a 63.3 MeV proton beam. The performance of chips after exposures up to 100 krad was within tolerances of an unexposed part

Proof-of-concept study: a mobile application to derive clinical outcome measures from expression and speech for mental health status evaluation

This proof-of-concept study aimed to assess the ability of a mobile application and cloud analytics software solution to extract facial expression information from participant selfie videos. This is one component of a solution aimed at extracting possible health outcome measures based on expression, voice acoustics and speech sentiment from video diary data provided by patients. Forty healthy volunteers viewed 21 validated images from the International Affective Picture System database through a mobile app which simultaneously captured video footage of their face using the selfie camera. Images were intended to be associated with the following emotional responses: anger, disgust, sadness, contempt, fear, surprise and happiness. Both valence and arousal scores estimated from the video footage associated with each image were adequate predictors of the IAPS image scores (p < 0.001 and p = 0.04 respectively). 12.2% of images were categorised as containing a positive expression response in line with the target expression; with happiness and sadness responses providing the greatest frequency of responders: 41.0% and 21.4% respectively. 71.2% of images were associated with no change in expression. This proof-of-concept study provides early encouraging findings that changes in facial expression can be detected when they exist. Combined with voice acoustical measures and speech sentiment analysis, this may lead to novel measures of health status in patients using a video diary in indications including depression, schizophrenia, autism spectrum disorder and PTSD amongst other conditions

A wearable headset for monitoring electromyography responses within spinal surgery

Purpose: This research examines an approach for enhancing the efficiency of spinal surgery utilising the technological capabilities and design functionalities of wearable headsets, in this case Google Glass. The aim was to improve the efficiency of the selective dorsal rhizotomy neurosurgical procedure initially through the use of Glass via an innovative approach to information design for an intraoperative monitoring display. Methods Utilising primary and secondary research methods the development of a new electromyography response display for a wearable headset was undertaken. Results: Testing proved that Glass was fit for purpose and that the new intraoperative monitor design provided an example platform for the innovative intraoperative monitoring display; however, alternative wearable headsets such as the Microsoft HoloLens could also be equally viable. Conclusion: The new display design combined with the appropriate wearable technology could greatly benefit the selective dorsal rhizotomy procedure

Graphene-like nano-sheets/36° LiTaO3 surface acoustic wave hydrogen gas sensor

Presented is the material and gas sensing properties of graphene-like nano-sheets deposited on 36deg YX lithium tantalate (LiTaO3) surface acoustic wave (SAW) transducers. The graphene-like nano-sheets were characterized via scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The graphenelike nano-sheet/SAW sensors were exposed to different concentrations of hydrogen (H2) gas in a synthetic air at room temperature. The developed sensors exhibit good sensitivity towards low concentrations of H2 in ambient conditions, as well as excellent dynamic performance towards H2 at room temperature

Radiation Testing of Electronics for the CMS Endcap Muon System

The electronics used in the data readout and triggering system for the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) particle accelerator at CERN are exposed to high radiation levels. This radiation can cause permanent damage to the electronic circuitry, as well as temporary effects such as data corruption induced by Single Event Upsets. Once the High Luminosity LHC (HL-LHC) accelerator upgrades are completed it will have five times higher instantaneous luminosity than LHC, allowing for detection of rare physics processes, new particles and interactions. Tests have been performed to determine the effects of radiation on the electronic components to be used for the Endcap Muon electronics project currently being designed for installation in the CMS experiment in 2013. During these tests the digital components on the test boards were operating with active data readout while being irradiated with 55 MeV protons. In reactor tests, components were exposed to 30 years equivalent levels of neutron radiation expected at the HL-LHC. The highest total ionizing dose (TID) for the muon system is expected at the inner-most portion of the CMS detector, with 8900 rad over ten years. Our results show that Commercial Off-The-Shelf (COTS) components selected for the new electronics will operate reliably in the CMS radiation environment

Relations Between Timing Features and Colors in the X-Ray Binary 4U 0614+09

We study the correlations between timing and X-ray spectral properties in the low mass X-ray binary 4U 0614+09 using a large (265-ks) data set obtained with the Rossi X-ray Timing Explorer. We find strong quasi-periodic oscillations (QPOs) of the X-ray flux, like the kilohertz QPOs in many other X-ray binaries with accreting neutron stars, with frequencies ranging from 1329 Hz down to 418 Hz and, perhaps, as low as 153 Hz. We report the highest frequency QPO yet from any low mass X-ray binary at 1329+-4 Hz, which has implications for neutron star structure. This QPO has a 3.5-sigma single-trial significance, for an estimated 40 trials the significance is 2.4-sigma. Besides the kilohertz QPOs, the Fourier power spectra show four additional components: high frequency noise (HFN), described by a broken power-law with a break frequency between 0.7 and 45 Hz, very low frequency noise (VLFN), which is fitted as a power-law below 1 Hz, and two broad Lorentzians with centroid frequencies varying from 6 to 38 Hz and 97 to 158 Hz, respectively. We find strong correlations between the frequencies of the kilohertz QPOs, the frequency of the 6 to 38 Hz broad Lorentzian, the break frequency of the HFN, the strength of both the HFN and the VLFN and the position of the source in the hard X-ray color vs. intensity diagram. The frequency of the 97 to 158 Hz Lorentzian does not correlate with these parameters. We also find that the relation between power density and break frequency of the HFN is similar to that established for black hole candidates in the low state. We suggest that the changing mass accretion rate is responsible for the correlated changes in all these parameters.Comment: ApJ, referee

Task-oriented intelligent solution to measure Parkinson’s disease tremor severity

Tremor is a common symptom of Parkinson’s disease (PD). Currently, tremor is evaluated clinically based on MDS-UPDRS Rating Scale, which is inaccurate, subjective, and unreliable. Precise assessment of tremor severity is the key to effective treatment to alleviate the symptom. Therefore, several objective methods have been proposed for measuring and quantifying PD tremor from data collected while patients performing scripted and unscripted tasks. However, up to now, the literature appears to focus on suggesting tremor severity classification methods without discrimination tasks effect on classification and tremor severity measurement. In this study, a novel approach to identify a recommended system is used to measure tremor severity, including the influence of tasks performed during data collection on classification performance. The recommended system comprises recommended tasks, classifier, classifier hyperparameters, and resampling technique. The proposed approach is based on the above-average rule of five advanced metrics results of four subdatasets, six resampling techniques, six classifiers besides signal processing, and features extraction techniques. The results of this study indicate that tasks that do not involve direct wrist movements are better than tasks that involve direct wrist movements for tremor severity measurements. Furthermore, resampling techniques improve classification performance significantly. The findings of this study suggest that a recommended system consists of support vector machine (SVM) classifier combined with BorderlineSMOTE oversampling technique and data collection while performing set of recommended tasks, which are sitting, stairs up and down, walking straight, walking while counting, and standing

Development of a PPE visor for female healthcare workers

During the COVID-19 pandemic the demand for personal protective equipment (PPE) has increased dramatically. However, the lack of PPE designed specifically for women is leaving many without adequate protection, as current “universal” solutions fail to address female healthcare workers’ varied needs. Instead, current solutions present users with a host of problems, including discomfort, hindrance, incompatibility with other wearable items, and adjustment difficulties. This paper explores and reflects upon the design thinking approach used to develop a PPE visor for female healthcare workers while following a user-centred design approach/methodology