Photo- and solvatochromic properties of nitrobenzospiropyran in ionic liquids containing the [NTf2]- anion

The photo-, thermo- and solvatochromic properties of 2,3-dihydro-10,30,30-trimethyl-6-nitrospiro- [1-benzopyran-2,20-1H-indole] (BSP-NO2) were studied in ILs containing the anion [NTf2]- by UV-Vis absorption spectroscopy, ab initio molecular orbital theory and density functional theory (DFT) calculations. It was found that the kinetics and thermodynamics of the BSP-NO2 MC (merocyanine) equilibrium was sensitive to the nature of the cation. It was also observed that the imidazolium cation can form a through-space orbital interaction with the MC isomer, rather than a simple electrostatic interaction, thus preventing the MC conversion back to the BSP-NO2 isomer. The BSP-NO2 MC equilibrium thus serves as a model system for studying modes of interaction of the cations in ionic liquids

Predicting sleep disordered breathing in outpatients with suspected OSA

Objective To validate the utilities of Berlin, STOP and STOP-BANG Questionnaires, other patient characteristics, comorbidities, Epworth Sleepiness Scale (ESS), fractional exhaled nitric oxide (FENO) and blood markers for the prediction of sleep disordered breathing (SDB) on limited polygraphy. Setting North Glasgow Sleep Service (a tertiary referral centre). Participants 129 consecutive patients, aged ≥16 years, referred to the sleep clinic for assessment of possible obstructive sleep apnoea. Interventions We selected cut-points of apnoea hypopnoea index (AHI) of ≥5 and ≥15/h from their home polygraphy and determined associations of these with individual symptoms, questionnaire scores and other results. Receiver operating characteristic analysis and univariate and multivariate logistic regression were used to explore these. Primary and secondary outcomes measures Primary: The utility of STOP, STOP-BANG and Berlin Questionnaires for prediction of SDB. Secondary: The utility of other measures for prediction of SDB. Results AHI was ≥5 in 97 patients and ≥15 in 56 patients. STOP and STOP-BANG scores were associated with both AHI cut-points but results with ESS and Berlin Questionnaire scores were negative. STOP-BANG had a negative predictive value 1.00 (0.77–1.00) for an AHI ≥15 with a score ≥3 predicting AHI ≥5 with sensitivity 0.93 (95% CI 0.84 to 0.98) and accuracy 79%, while a score ≥6 predicted AHI ≥15 with specificity 0.78 (0.65 to 0.88) and accuracy 72%. Neck circumference ≥17 inch and presence of witnessed apnoeas were independent predictors of SDB. Conclusions STOP and STOP-BANG Questionnaires have utility for the prediction of SDB in the sleep clinic population. Modification of the STOP-BANG Questionnaire merits further study in this and other patient groups.</p

A sub-critical barrier thickness normally-off AlGaN/GaN MOS-HEMT

A new high-performance normally-off gallium nitride (GaN)-based metal-oxide-semiconductor high electron mobility transistor that employs an ultrathin subcritical 3 nm thick aluminium gallium nitride (Al0.25Ga0.75N) barrier layer and relies on an induced two-dimensional electron gas for operation is presented. Single finger devices were fabricated using 10 and 20 nm plasma-enhanced chemical vapor-deposited silicon dioxide (SiO2) as the gate dielectric. They demonstrated threshold voltages (Vth) of 3 and 2 V, and very high maximum drain currents (IDSmax) of over 450 and 650 mA/mm, at a gate voltage (VGS) of 6 V, respectively. The proposed device is seen as a building block for future power electronic devices, specifically as the driven device in the cascode configuration that employs GaN-based enhancement-mode and depletion-mode devices

Evaluation of electrochemical methods for determination of the seebeck coefficient of redox electrolytes

Recent advances in thermoelectrochemical cells, which are being developed for harvesting low grade waste heat, have shown the promise of cobalt bipyridyl salts as the active redox couple. The Seebeck coefficient, Se, of a redox couple determines the open circuit voltage achievable, for a given temperature gradient, across the thermoelectrochemical cell. Thus, the accurate determination of this thermodynamic parameter is key to the development and study of new redox electrolytes. Further, techniques for accurate determination of Se using only one half of the redox couple reduces the synthetic requirements. Here, we compare three different experimental techniques for measuring Se of a cobalt tris(bipyridyl) redox couple in ionic liquid electrolytes. The use of temperature dependent cyclic voltammetry (CV) in isothermal and non-isothermal cells was investigated in depth, and the Se values compared to those from thermo-electromotive force measurements. Within experimental error, the Se values derived from CV methods were found to be in accordance with those obtained from electromotive force (emf) measurements. The applicability of cyclic voltammetry techniques for determining Se when employing only one part of the redox couple was demonstrated

Design and fabrication of AlGaN/GaN HEMTs with high breakdown voltages

Gallium nitride based transistors will make up a large portion of the power electronics and the microwave electronics sectors in the very near future, replacing traditional materials such as silicon (Si) and gallium arsenide (GaAs). The work in this thesis focuses on AlGaN/GaN high electron mobility transistors (HEMTs) in particular, with the aim of gaining the maximum potential out of them with regards to breakdown voltage. GaN based devices are able to breakdown at higher voltages compared to Si or GaAs due to its wider band gap (3.4 eV compared to 1.1 eV and 1.4 eV respectively) and although a lot of work has been invested into these devices over the last two decades or so, their full potential has yet to be realised and new solutions are still sought to provide a complete engineering solution which will make them competitive and commercially viable. One of the main obstacles is the high electric fields generated at the drain side of the gate which have prevented these devices from reaching their theoretical breakdown fileld of around 300 V/um. In an attempt to overcome this, several approaches have been investigated in this thesis including metal insulator semiconductor HEMTs (MIS-HEMTs), `gate overlapping' HEMTs, where the gate partially overlaps the source and drain contacts and finally a device employing a Schottky source and a Schottky drain contact. The results given show that a MIS-HEMT can have a substantially larger breakdown voltage compared to a Schottky gate HEMT which is clarified through qualitative simulated electric field work and experimental work. Further, the MIS-HEMT shows a high breakdown field of about 87 V/um when a Schottky drain contact is incorporated. The gate overlapping HEMTs attempts to mitigate completely the large electric field found at the drain edge of the gate. Simulated and experimental results are given for this device concept and reveal that the large electric field peak is indeed removed, however, low breakdown voltages are still incurred due to the closeness of the gate edge to the drain contact. Finally, results are given for a device employing Schottky source and Schottky drain contacts and reveals that present theory may not completely describe the operation of this device

Governance Strategies Towards Organising for Action Sports: A National Structure for New Zealand Skateboarding

This study examines the processes and politics involved in the sportisation and institutionalisation of skateboarding in Aotearoa, New Zealand. In 2016, the IOC announced that skateboarding would debut at the Tokyo 2020 Games, and its governance was given to the ISF World Skate (i.e. a partnership between the Fédération Internationale de Roller Sports and International Skateboarding Federation). However, in many countries, including New Zealand (NZ), skateboarding was largely an informal activity, ungoverned and lacking structure, and with some resistance to Olympic inclusion. This research explores and documents the views of various skateboarding-related stakeholder groups, and governmental and national sport bodies regarding establishing a governing structure for NZ skateboarding between 2016-2022. Employing a social constructionist approach, I draw on qualitative methods, including in-depth interviews, participant observations, document analysis, and secondary data exploration, to document the perceptions of key individuals involved in the organisational development and/or institutionalisation of NZ skateboarding. Twenty-five interviews were conducted across sport and skateboarding-related organisations involved in this process, including Skateboarding New Zealand (i.e. SBNZ, a new skater-led organisation), New Zealand Federation of Roller Sports (Skate NZ), New Zealand Olympic Committee (NZOC), Sport New Zealand (Sport NZ), regional skateboarding associations, skate schools, and skateboarding event owners/organisers. The project includes an organisational ethnography focused on the evolution of the skater-led association SBNZ between late-2018 and mid-2022. Drawing on sport sociology, sport management and organisational studies, this project maps the development of skateboarding culture, industry, its organisation and those stakeholder groups that provide for NZ skateboarding. It reveals the unique structures and social dynamics evident in the community-led events, media and venues (i.e. skateparks). The research also reveals the processes and politics involved in developing “legitimate” forms of governance in the NZ skateboarding context. There are competing external factors as SBNZ seeks to manage its “regulative legitimacy” with the Mainstream Sport Governing Bodies (MSGBs): Skate NZ, Sport NZ, NZOC, and World Skate Oceania. Simultaneously, SBNZ experiences cultural challenges to its “cultural legitimacy” or “authenticity” with the NZ sport-skateboarding community. The traditional (and familiar) “umbrella” and federated sport models provide the MSGBs with the comprehension and predictability they need to govern SBNZ. In contrast, for SBNZ, adopting the traditional sport model is challenging and development-inhibiting as the organisation lacks the pre-existing infrastructure, necessary funding, expert knowledge/support, and the desire to institutionalise in such a manner. However, there are some mutual benefits in the SBNZ/Skate NZ relationship, mainly where there is room for flexibility regarding the umbrella governance’s processes and responsibilities. The research suggests a need for MSGBs to be more open to recognising alternative forms of governance and structure for action sports. However, this will require a philosophical shift in how MSGBs view governance, structure and sport, and funding models. As well as contributing to the international literature on the institutionalisation of action sports, this study will also usefully inform future developments in the national and international sports context to facilitate inclusion, recognition and support for current and future forms of sport engagement for both action and mainstream sports

1-Methyl-1-propyl­pyrrolidinium chloride

The aymmetric unit of the title compound, C8H18N+·Cl−, consists of one crystallographically independent 1-methyl-1-propyl­pyrrolidinium cation and one chloride anion, both of which lie in general positions. Minor hydrogen-bonded C—H⋯Cl inter­actions occur. However, no classical hydrogen bonding is observed