AquaSift: point-of-use microfluidic detection system

AquaSift is a portable, affordable, point-of-use system that performs microfluidic detection of contaminants in drinking water. It comprises four main components: a three-electrode sensor, a potentiostat circuit device, an Android application, and an online database. It utilizes three-electrode voltammetry by applying a voltage stimulus across the electrodes and reading the induced current on the water sample. Testing has shown that our system is able to detect arsenic in solution samples. The Android application serves as the user interface to the system, and the online database allows the mapping of test results on an easy-to-use website

Identification of dengue virus (DENV) NS1 protein residues involved in its cellular secretion and host factors involved in NS1 protein N-glycosylation

Dengue virus (DENV) is a Flavivirus of the Flaviviridae family of (+) RNA viruses. It is known to cause approximately 390 million infections and 25,000 deaths annually in tropical and sub-tropical areas across the world. DENV infection has a wide spectrum of clinical manifestations ranging from mild fever to severe forms of dengue; formerly referred to as dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS). The viral NS1 protein is secreted from DENV-infected cells as a soluble hexameric lipoparticle that can induce vascular leakage; an established hallmark of DENV disease pathogenesis. Despite widespread acknowledgement of the importance of NS1 secretion in DENV pathogenesis, the exact molecular features of NS1 that are critical for its secretion from infected cells are not fully characterised. In this study, we employed random point mutagenesis and a luminescent ‘HiBiT’ peptide tag assay approaches to identify NS1 residues that are essential for its efficient secretion. From these approaches, we identified 10 point mutations that correlated with impaired NS1 secretion, with subsequent in silico analyses demonstrating that the majority of these mutations are located within the β-ladder domain of NS1. More detailed studies on two of these mutations V220D and A248V, revealed they also abrogated viral RNA replication and infectious virus production. Subsequent analyses of these mutants by confocal microscopy in the context of a DENV non-structural protein expression system revealed a similar but more reticular NS1 localisation pattern, while these mutant NS1 proteins could not be detected by immunoblotting using a conformation specific NS1 monoclonal antibody. Together, these studies demonstrated that the V220D and A248V mutations of NS1 may disrupt multiple functions and properties of the protein, as might occur if it is improperly folded and/or cannot form critical interactions with other proteins or membranes. Next, we sought to identify novel host factors associated with NS1 N-glycosylation, an essential post-translational modification of NS1, using an APEX2-based proximity biotinylation labelling approach and quantitative proteomics. Towards this goal, appropriate virus constructs were generated for wildtype and N-glycosylation NS1 mutants. Following the comprehensive testing of a variety of constructs and optimisation of transfection and proximity biotinylation conditions, large scale experiments were conducted, and lysates were prepared for future streptavidin pulldowns and quantitative proteomics analyses. Taken together, these studies employed a combination of random point mutagenesis and sensitive luminescent peptide assays to identify a panel of mutations that impair NS1 secretion activity. A novel proximity labelling-based experimental workflow was also developed and applied towards proteomics-mediated identification of NS1 proximal proteins and how the NS1 protein microenvironment is altered by mutational disruption of NS1 N-glycosylation. We propose that NS1 secretion and N-glycosylation may represent novel and viable targets for future antiviral drug and attenuated vaccine development.Thesis (Ph.D.) -- University of Adelaide, School of Biological Sciences, 202

Development of the PEBL Traveling Salesman Problem Computerized Testbed

The traveling salesman problem (TSP) is a combinatorial optimization problem that requires finding the shortest path through a set of points (“cities”) that returns to the starting point. Because humans provide heuristic near-optimal solutions to Euclidean versions of the problem, it has sometimes been used to investigate human visual problem solving ability. The TSP is also similar to a number of tasks commonly used for neuropsychological assessment (such as the trail-making test), and so its utility in assessing reliable individual differences in problem solving has sometimes been examined. Nevertheless, the task has seen little widespread use in clinical and assessment domains, in part because no standard software implementation or item set is widely available with known psychometric properties. In this paper, we describe a computerized version of TSP running in the free and open source Psychology Experiment Building Language (PEBL). The PEBL TSP task is designed to be suitable for use within a larger battery of tests, and to examine both standard and custom TSP node configurations (i.e., problems). We report the results of a series of experiments that help establish the test’s reliability and validity. The first experiment examines test-retest reliability, establishes that the quality of solutions in the TSP are not impacted by mild physiological strain, and demonstrates how solution quality obtained by individuals in a physical version is highly correlated with solution quality obtained in the PEBL version. The second experiment evaluates a larger set of problems, and uses the data to identify a small subset of tests that have maximal coherence. A third experiment examines test-retest reliability of this smaller set that can be administered in about five minutes, and establishes that these problems produce composite scores with moderately high (R = .75) test-retest reliability, making it suitable for use in many assessment situations, including evaluations of individual differences, personality, and intelligence testing

Design, fabrication, and implementation of a wireless, passive implantable pressure sensor based on magnetic higher-order harmonic fields

A passive and wireless sensor was developed for monitoring pressure in vivo. Structurally, the pressure sensor, referred to as the magneto-harmonic pressure sensor, is an airtight chamber sealed with an elastic pressure membrane. A strip of magnetically-soft material is attached to the bottom of the chamber and a permanent magnet strip is embedded inside the membrane. Under the excitation of an externally applied AC magnetic field, the magnetically-soft strip produces a higher-order magnetic signature that can be remotely detected with an external receiving coil. As ambient pressure varies, the pressure membrane deflects, altering the separation distance between the magnetically-soft strip and the permanent magnet. This shifts the higher-order harmonic signal, allowing for detection of pressure change as a function of harmonic shifting. The wireless, passive nature of this sensor technology allows for continuous long-term pressure monitoring, particularly useful for biomedical applications such as monitoring pressure in aneurysm sac and sphincter of Oddi. In addition to demonstrating its pressure sensing capability, an animal model was used to investigate the efficacy and feasibility of the pressure sensor in a biological environment

A wireless, passive sensor for quantifying packaged food quality

This paper describes the fabrication of a wireless, passive sensor based on aninductive-capacitive resonant circuit, and its application for in situ monitoring of thequality of dry, packaged food such as cereals, and fried and baked snacks. The sensor ismade of a planar inductor and capacitor printed on a paper substrate. To monitor foodquality, the sensor is embedded inside the food package by adhering it to the package’sinner wall; its response is remotely detected through a coil connected to a sensor reader. Asfood quality degrades due to increasing humidity inside the package, the paper substrateabsorbs water vapor, changing the capacitor’s capacitance and the sensor’s resonantfrequency. Therefore, the taste quality of the packaged food can be indirectly determined bymeasuring the change in the sensor’s resonant frequency. The novelty of this sensortechnology is its wireless and passive nature, which allows in situ determination of foodquality. In addition, the simple fabrication process and inexpensive sensor material ensure alow sensor cost, thus making this technology economically viable

Implantable biosensors for real-time strain and pressure monitoring

Implantable biosensors were developed for real-time monitoring of pressure and strain in the human body. The sensors, which are wireless and passive, consisted of a soft magnetic material and a permanent magnet. When exposed to a low frequency AC magnetic field, the soft magnetic material generated secondary magnetic fields that also included the higher-order harmonic modes. Parameters of interest were determined by measuring the changes in the pattern of these higher-order harmonic fields, which was achieved by changing the intensity of a DC magnetic field generated by a permanent magnet. The DC magnetic field, or the biasing field, was altered by changing the separation distance between the soft magnetic material and the permanent magnet. For pressure monitoring, the permanent magnet was placed on the membrane of an airtight chamber. Changes in the ambient pressure deflected the membrane, altering the separation distance between the two magnetic elements and thus the higher-order harmonic fields. Similarly, the soft magnetic material and the permanent magnet were separated by a flexible substrate in the stress/strain sensor. Compressive and tensile forces flexed the substrate, changing the separation distance between the two elements and the higher-order harmonic fields. In the current study, both stress/strain and pressure sensors were fabricated and characterized. Good stability, linearity and repeatability of the sensors were demonstrated. This passive and wireless sensor technology may be useful for long term detection of physical quantities within the human body as a part of treatment assessment, disease diagnosis, or detection of biomedical implant failures

ExoMol line lists – XLV. Rovibronic molecular line lists of calcium monohydride (CaH) and magnesium monohydride (MgH)

New molecular line lists for calcium monohydride ({40}^Ca^{1}H) New molecular line lists for calcium monohydride ({40}^Ca^{1}H) and its minor isotopologues ({25}^Mg^{1}H and {26}^Mg^{1}H) are presented. The rotation-vibration-electronic (rovibronic) line lists, named XAB, consider transitions involving the X^{2}Σ^{+}, A{2}^Π, and B/B′ {2}^Σ^{+} electronic states in the 0–30 000 cm^{−1} region (wavelengths λ > 0.33 μm) and are suitable for temperatures up to 5000 K. A comprehensive analysis of the published spectroscopic literature on CaH and MgH is used to obtain new extensive datasets of accurate rovibronic energy levels with measurement uncertainties and consistent quantum number labelling. These datasets are used to produce new spectroscopic models for CaH and MgH, composed of newly empirically-refined potential energy curves and couplings in/between the different electronic states (e.g. spin-orbit, electronic angular momentum, Born-Oppenheimer breakdown, spin-rotation, Λ-doubling) and previously published ab initio transition dipole moment curves. Along with Einstein A coefficients, state lifetimes and Landé g-factors are provided, the latter being particularly useful as CaH and MgH can be used to probe stellar magnetic fields. Computed energy levels have been replaced with the more accurate empirical values (if available) when post-processing the line lists, thus tailoring the line lists to high resolution applications. The XAB line lists are available from the ExoMol database at www.exomol.com and the CDS astronomical database