Magdalena Wajrak

Manufacture and application of RuO2 solid-state metal-oxide pH sensor to common beverages

A new reproducible solid-state metal-oxide pH sensor for beverage quality monitoring is developed and characterised. The working electrode of the developed pH sensor is based on the use of laser-etched sputter-deposited RuO2 on Al2O3 substrate, modified with thin layers of sputter-deposited Ta2O5 and drop-cast Nafion for minimisation of redox interference. The reference electrode is manufactured by further modifying a working electrode with a porous polyvinyl butyral layer loaded with fumed SiO2. The developed pH sensor shows excellent performance when applied to a selection of beverage samples, with a measured accuracy within 0.08 pH of a commercial glass pH sensor.

Effect of ordered mesoporous carbon contact layer on the sensing performance of sputtered RuO2 thin film pH sensor

The effect of contact layer on the pH sensing performance of a sputtered RuO2 thin film pH sensor is investigated. The response of pH sensors employing RuO2 thin film electrodes on screen-printed Pt, carbon and ordered mesoporous carbon (OMC) contact layers are measured over a pH range from 4 to 10. Working electrodes with OMC contact layer are found to have Nernstian pH sensitivity (-58.4mV/pH), low short-term drift rate (5.0mV/h), low hysteresis values (1.13mV) and fast reaction times (30s), after only 1h of conditioning. A pH sensor constructed with OMC carbon contact layer displays improved sensing performance compared to Pt and carbon-based counterparts, making this electrode more attractive for applications requiring highly-accurate pH sensing with reduced conditioning time.

RuO2 pH sensor with super-glue-inspired reference electrode

A pH-sensitive RuO2 electrode coated in a commercial cyanoacrylate adhesive typically exhibits very low pH sensitivity, and could be paired with a RuO2 working electrode as a differential type pH sensor. However, such sensors display poor performance in real sample matrices. A pH sensor employing a RuO2 pH-sensitive working electrode and a SiO2-PVB junction-modified RuO2 reference electrode is developed as an alternative high-performance solution. This sensor exhibits a performance similar to that of a commercial glass pH sensor in some common sample matrices, particularly, an excellent pH sensitivity of 55.7 mV/pH, a hysteresis as low as 2.7 mV, and a drift below 2.2 mV/h. The developed sensor structure opens the way towards the development of a simple, cost effective, and robust pH sensor for pH analysis in various sample matrices.

Participatory action and dual lens research

Purpose The purpose of this paper is to explore the idea that, in the last few decades, collaborative inquiry methods have evolved along a similar trajectory to dual lens research. Dual lens research, known in various contexts as both ways, two-eyed seeing Old Ways New Ways, and Koodjal Jinnung (looking both ways), is designed to generate new knowledge by exploring a theme through Aboriginal and contemporary western lenses. Participatory action research and a dual lens approach are considered in a number of projects with a particular focus on the issues such work can raise including conceptual challenges posed by fundamental differences between knowledge sets. Design/methodology/approach The authors hypothesize that a dual lens approach will become a branch of participatory action research, as such, a robust description needs to be developed and its ethical implications are considered. Existing work in this direction, including principles and processes, are collated and discussed. Findings Dual lens research as a branch of participatory action research is of great significance in countries with Aboriginal populations that are undergoing a cultural renaissance. As dual lens practitioners, the authors are finding their research outputs have a high positive impact on both Aboriginal and non-Aboriginal populations and make a genuine contribution to reconciliation by finding ways of going forward together. Originality/value This paper joins a growing body of research that supports resonances between Aboriginal and “western” research methods.

Neutron diffraction structures of water in crystalline hydrates of metal salts

Neutron diffraction structures of water molecules in crystalline hydrates of metal salts have been collected from the literature up to December 2011. Statistical methods were used to investigate the influence on the water structures of the position and nature of hydrogen bond acceptors and cations coordinated to the water oxygen. For statistical modelling the data were pruned so that only structures with oxygen as hydrogen acceptors, single hydrogen bonds, and no more than two metals or hydrogens coordinated to the water oxygen were included. Multiple linear regression models were fitted with the water OH bond length and bond angle as response variables. Other variables describing the position and nature of the acceptors and ions coordinated to the waters were taken as explanatory variables. These variables were sufficient to give good models for the bond lengths and angles. There were sufficient structures involving coordinated Mg(2+) or Cu(2+) for a separate statistical modelling to be done for these cases.