EFFECTS OF CONFINEMENT ON IONIC LIQUIDS AND DEEP EUTECTIC SOLVENTS FOR THE DESIGN OF CATALYTIC SYSTEMS, ELECTROCHEMICAL DEVICES, AND SEPARATIONS

Confinement of ionic liquids (ILs) and deep eutectic solvents (DESs) within mesoporous materials such as silica helps to control the local environment within the pores for applications such as catalysis, electrochemistry, and absorption. Silica thin films with 2.5 and 8 nm pores and micron-sized silica particles with pore diameters of 5.4 and 9 nm were synthesized to study the effect of nanoconfinement on ILs 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]), and DESs reline and ethaline (choline chloride and urea or ethylene glycol). Silica thin films with vertically aligned, well ordered, and accessible pores were synthesized via the evaporation-induced self-assembly (EISA) method with cetyltrimethylammonium bromide (CTAB) templated EISA and titania doping giving 2.5 nm pores and Pluronic P123 (P123) templated films with a neutrally charged substrate giving 8 nm pores. Grazing incidence small angle x-ray scattering (GISAXS) and transmission electron microscopy (TEM) characterization gave evidence that the pores were aligned perpendicular to the substrate. Micron-sized mesoporous silica nanoparticles were synthesized through a sol-gel hydrothermal aging method where CTAB and P123 are used for templating and the pore diameter may be controlled through temperature, with higher temperatures giving larger pore sizes (2-12 nm). Diffusion properties of confined ILs is relevant to understanding how solute molecules will behave when entering and moving through the confined IL. The diffusivity of a probe molecule to serve as an example solute are two fluorescent dyes rhodamine 6G (R6G), a cationic dye, and 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM), a neutral dye. The dyes were mixed with [BMIM][PF6] and confined within mesoporous silica microparticles with 5.4 and 9 nm pores. The 9 nm diameter particles were functionalized (tethered) with an IL-like molecule, 3-methyl-1-[3-(trimethoxysilyl)propyl]-1-imidazolium chloride [TMS-MIM][Cl]. The fluorescence recovery after photobleaching (FRAP) technique in confocal microscopy was used to estimate the diffusivity of the probes within the confined IL. Water saturated particles and pore diameter differences did not significantly impact the diffusion. The cationic dye had a lower diffusivity than the neutral dye from interactions between the dye and pore wall and anion of IL, while tethering increased the diffusivity of the dye by making the interior of the pore more hydrophobic. These results are important for diffusion considerations of species to catalytic sites in nanoconfined IL. To further understand the interactions between ILs and the silica substrate, mesoporous silica thin films were synthesized with 3.5 and 8.5 nm pores and loaded with [BMIM][Cl]. The 8.5 nm pores were also functionalized with [TMS-MIM][Cl]. The films were characterized with x-ray photoelectron spectroscopy to measure the electronic environment of the elements within the sample. Bulk IL only has one peak in the nitrogen spectra due to the shared positive charge on the imidazolium ring. After confinement, a second peak at lower binding energy (BE) appeared from interfacial interactions between the imidazolium group in the IL with the pore wall of the silica. The reduction in positive charge on the imidazolium from this interaction causes a reduction in BE. This work gives insight into the ordering and location of the IL within the pores and is an important consideration since catalysis occurs on the surface of a material. DESs are an emerging area of alternative solvents; often considered analogous to ILs, they are made of natural components that are customizable (choline chloride and urea being the classical example) but are still usually highly viscous so confinement is still advantageous. They can be used as a solvent for catalysis with metal additives, so the diffusion of FeCl3 was studied using cyclic voltammetry. Mesoporous silica thin films with 3 and 8 nm pores were synthesized as above on Fluorine-doped Tin Oxide glass slides and used as a working electrode. The diffusion was calculated using the Randles-Sevcik equation where the diffusion can be calculated by varying the voltage scan rate and measuring the peak current output for either the oxidation or reduction event of the probe molecule. The diffusion of FeCl4- in reline was hindered significantly in both pore diameters compared to the bulk value, while ethaline had pore size dependent accessibility. This result is beneficial to catalysis and electrochemical research with redox active species

Spatial Release from Masking in Anechoic and Reverberant Environments

Listening with both ears provides children with access to binaural and monaural cues that are helpful for understanding speech in competing babbles. Specifically, when the target and masker are spatially separated, children can gain an intelligibility benefit which is known as spatial release from masking (SRM). Recent work [Peng et al., 2021 JASA] suggested that school-age children demonstrated immature SRM using binaural cues that are distorted by reverberation. In this follow-up study, we further investigate the effect of reverberant distortion on individual auditory spatial cues, namely binaural and monaural head shadow cues. We compare SRM between adults and school-age children with typical hearing using the novel measure of minimum angle of separation (MAS) between target and masker for which individual achieves a 20% intelligibility gain, in both virtually simulated anechoic and reverberant environments. MAS was measured in both binaural and monaural hearing conditions, as well symmetric versus asymmetric masker displacement to probe access to various auditory cues of interest. Preliminary results show statistically significant effect on MAS when comparing binaural and monaural conditions as well as when comparing symmetric and asymmetric masking conditions. Binaural listening seems to have a positive effect on MAS. Asymmetric masking also seems to improve MAS. Advisor: Lily M. Wan

Widening and increasing post-16 mathematics participation: pathways, pedagogies and politics

This paper explores the potential impact of a national pilot initiative in England aimed at increasing and widening participation in advanced mathematical study through the creation of a new qualification for 16 to 18 year-olds. This proposed qualification pathway - Use of Mathematics - sits in parallel with long-established, traditional advanced level qualifications; what we call ‘traditional Mathematics’ herein. Traditional Mathematics is typically required for entry to mathematically demanding undergraduate programmes. The structure, pedagogy and assessment of Use of Mathematics is designed to better prepare students in the application of mathematics and its development has surfaced some of the tensions between academic/pure and vocational/applied mathematics. Here we explore what Use of Mathematics offers but we also consider some of the objections to its introduction in order to explore aspects of the knowledge-politics of mathematics education. Our evaluation of this curriculum innovation raises important issues for the mathematics education community as countries seek to increase the numbers of people that are well-prepared to apply mathematics in science and technology-based higher education courses and work places

THE CONTRIBUTION OF THE FLIGHT PHASE IN ELITE RACE WALKING

Although race walkers are not permitted a visible flight phase, previous research has found that most competitors do experience very brief losses of contact. The purpose of this study was to assess the role of the flight phase in elite race walking. Seventeen international athletes race walked over two force plates recording at 1000 Hz. Video data were simultaneously recorded at 100 Hz and used to calculate kinematic variables such as step length. The mean flight time was 0.030 s (± .011) while the mean distance travelled during this phase was 0.12 m (± .05). It was calculated that without flight times, athletes would have slower mean velocities, particularly if mean cadence remained the same. However, the contribution of flight phases in race walking does not just allow for greater step lengths and faster speeds, but also more time for lower limb repositioning

The Validation of a Functional, Isolated Pig Bladder Model for Physiological Experimentation

Characterizing the integrative physiology of the bladder requires whole organ preparations. The purpose of this study was to validate an isolated large animal (pig) bladder preparation, through arterial and intravesical drug administration, intravesical pressure recording, and filming of surface micromotions. Female pig bladders were obtained from the local abattoir and arterially perfused in vitro. Arterial and intravesical pressures were recorded at varying volumes. Bladder viability was assessed histologically and by monitoring inflow and outflow pH. Arterial drug administration employed boluses introduced into the perfusate. Intravesical administration involved slow instillation and a prolonged dwell-time. Surface micromotions were recorded by filming the separation of surface markers concurrently with intravesical pressure measurement. Adequate perfusion to all bladder layers was achieved for up to 8 h; there was no structural deterioration nor alteration in inflow and effluent perfusate pH. Arterial drug administration (carbachol and potassium chloride) showed consistent dose-dependent responses. Localized movements (micromotions) occurred over the bladder surface, with variable correlation with fluctuations of intravesical pressure. The isolated pig bladder is a valid approach to study integrative bladder physiology. It remains viable when perfused in vitro, responds to different routes of drug administration and provides a model to correlate movements of the bladder wall directly to variation of intravesical pressure

The Catalina Real-Time Transient Survey (CRTS)

The Catalina Real-time Transient Survey (CRTS) is a completely open, VOEvent-enabled, optical transient survey that provides a model for the large synoptic surveys of the future. CRTS has so far discovered more than 7,000 highly variable and transient sources including 2,000 supernovae and 1,000 catalysmic variables. I will highlight some of the rare and extreme types optical transients discovered by CRTS, as well as how increases in coverage and cadence of our second generation project, CRTS-II, will aid the discovery of new types of transient objects and phenomena. Lastly, I will discuss on-going efforts to characterize the variable sky using nine years of Catalina data for 500 million sources

Flight Readiness Review (FRR): Are you ready to fly?

A Flight Readiness Review evaluates the readiness to begin and safely conduct flight tests or flight operations. FRR approval is necessary in order to determine that the system under review can proceed into its test environment having met the standards to be considered airworthy. These standards require that the aviation system be under configuration management, have flight clearance, approved flight test plans, discrepancy tracking, and appropriate risk assessment processes in place. As an Autonomous Flight Lab we are interested in developing a protocol that will make this processes more accessible to individuals trying to utilize UAVs for various research projects. Currently there is no process in place to assist individuals in preparing an FRR. We have been working on generating a user friendly guide to developing quality student presentations in the form of FRRs. We began by observing student FRR presentations, determining the best procedure for risk assessment, and specifying base line operation requirements. In order to do so one must first identify the vehicle being used, the mission details, the necessary crew members, and the operational environment. Ultimately we hope that by having a procedure in place to assist individuals in developing FRRs, we can greatly reduce lab member dependency and need for multiple FRR revisions