The large availability of Kraft lignin as an industrial by-product and its polyaromatic characteristic, is ideal to consider the potential for recycling it into fine chemicals. To depolymerise lignin, solvolysis and hydrogenolysis experiments were performed. This research considered whether the low yields of products (fine chemicals) were related to the low content of β-O-4 bonds or if it was also associated to the dissolution of lignin in the solvent solution employed in the reactions. The type of solvents chosen to check the dissolution effect were those with low cost and were more sustainable than traditional solvents. Water, ethanol, isopropanol (IPA) and acetone were used. The water mixtures were applied in the tests in various proportions (25:75, 50:50, 75:25 solvent/water v:v). Due to their ability to break C-C and C-O bonds in lignin model compounds [1][2], the efficiency of platinum and rhodium in these reactions supported on alumina was also studied. It was found that the non-catalysed (solvolysis) and catalysed reactions showed different selectivities but similar overall yields ~ 10 % wt of monomeric phenols. The difficulty in increasing yields was mainly associated with the highly condensed character of Kraft lignin and re-polymerisation issues. To achieve an understanding of Kraft lignin depolymerisation, isotopic labelling reactions were completed in the presence of deuterated solvents as well as deuterium gas. This gave information on how Kraft lignin depolymerises, the influence of solvent to products formation and the involvement of hydrogen in the rate determining steps in the reactions. These results have led to an initial mechanistic understanding on how this complex molecule may yield alky-phenolic compounds. It was revealed that the solvent was directly involved in the products’ formation and that they were not generated by simple thermolysis. In addition, the presence of catalysts and hydrogen influenced product formation. The compounds showed different kinetic isotopic values, suggesting that each of these molecules came from individual mechanisms, highlighting the complexity of their formation. This was a relevant study as most of lignin depolymerisation mechanistic insights are based on model compounds and not on lignin itself. It was of interest to this project to explore not only different catalysts and their relationship to lignin depolymerisation, but also different lignin types. A simple pre-treatment for lignin extraction using sawdust (from oak and birch wood) in a Parr autoclave reactor in the presence of hydrogen, solvent and high temperature was developed. The lignins obtained after the pre-treatment were named parr-lignin and successfully resulted in polyaromatic molecules with less condensed character compared to lignins from Soda or Kraft pulping. Reactions were carried out with these lignins and a sugar-cane lignin. 4 5 Different catalytic systems with these lignins were investigated and how depolymerisation was affected by the metal and support used. The catalysts involved in the reactions included platinum, rhodium, nickel and iron. Various supports such as alumina, zirconia and carbon were tested along with the metals described. It was found that the supports were not inert in these experiments presenting catalytic activity. Materials with low surface area (zirconium catalysts) gave a poor performance compared to the others. In addition, nickel, a non-noble metal, showed as good a catalytic effect in the depolymerisation of these lignins as Pt and Rh. The components in the system influenced the reactions to different extents, especially product distribution. The catalysts had different selectivities and the solvents were not only dissolving lignin but also influencing the results. GPC analysis was performed to give an overview of the condensed level of these lignins and degrees of depolymerisation compared to the original material. GC-MS enabled the identification and quantification of 18 monomeric compounds. The post reaction characterisation of selected alumina catalysts (Pt/Al2O3, Ni/Al2O3 and Al2O3) was performed using XRD, BET, CHN, TPO and Raman Analysis to study the nature of the carbonaceous layer deposited on these materials. The work showed that after reaction the catalysts turned black in colour and the carbon laydown consisted of not only one simple type of carbon, and included graphitic species. The amount of carbon deposited depended on the type of lignin. Oak and birch parr-lignins had the highest and lowest amount of carbon over the catalysts respectively. No obvious trend relating to the type of catalyst, lignin and solvent used to the carbon nature was identified. This work showed that lignins with less condensed nature were less susceptible to solvolysis and more to hydrogenolysis. For example, sugar-cane lignin gave 3.9% of phenolic compounds in the solvolysis while reaction with Rh/Al2O3 gave 12.9% of products. This indicated that more selective cleavage of bonds were promoted by heterogenous catalysts. The results suggested that some compounds were mainly generated via dealkylation and hydrodeoxygenation, allowing a future possibility to generate target molecules. These results were mainly due to the presence of more labile bonds, vulnerable to hydrogenolysis. Highlighting that prior to depolymerisation, the pre-treatment used to extract lignin must be appropriate to avoid depletion of the alkyl-aryl ether bonds (β-O-4 bonds, especially) relevant for fine chemicals generation.

Filamentous micro-organisms, grown in submerged culture, are used in a large number of fermentation processes, such as the production of penicillin and citric acid. Generally, production takes place in baffled sparged vessels agitated by either single or multiple impellers, traditionally Rushton turbines mounted on a common shaft. This configuration is satisfactory for low viscosity systems, e.g. yeast and some bacterial fermentations. However, in cultures of filamentous fungi, as the fermentation time progresses, the broth may become increasingly viscous, and possibly shear thinning, with the consequent onset of dead zones or stagnant regions. The resulting concentration gradients may cause a reduction in the productivity. It may be possible to overcome these problems by using a fermenter which has two independently driven impellers and a cylindrical draft tube (IDDIDT i.e. an acronym for "Independently Driven Dual Impeller with Draft Tube") Studies have been undertaken in a 0.75 m Perspex proto-fermenter employing a Rushton turbine (6RT) and a Scaba 3SHP1 axial flow impeller, with test fluids such as water and CMC, under unaerated and aerated conditions. In order to fully characterise the system, important mixing aspects such as mass transfer (hold-up, k\(_L\)a) and bulk blending (mixing times, circulation time distributions) were investigated and related to the power input from each impeller. At low gas rates, moderately increased hold-up and k\(_L\)a values were observed with the IDDIDT compared to single or dual Rushton turbine systems. At higher gassing rates the performance was similar for all configurations. For the IDDIDT, regardless of the proportion of the total energy dissipation rate contributed by each impeller, the k\(_L\)a was the same. In addition, very rapid mixing times approximately 3 times faster than predicted by correlations for single impeller, single shaft systems and experimentally determined values for the dual Rushton system, were observed. Mixing times could be directly controlled by the 3SHP1 axial flow impeller, and confirmation of the increased exchange flow rate throughout the vessel was achieved via circulation time distribution (CTD) experiments. Since very little data has been published regarding the use of fermentation broths in these systems, hygienic Aspergillus niger fermentations were carried out in the fermenter to clarify any improvements when using the novel reactor and also to highlight any discrepancies in the use of test fluids, such as CMC, as model broths. Although unaerated and aerated power characteristics were similar for both the test fluids and fermentation broths the hold-up values varied considerably, probably due to differing coalescence characteristics. Productivity (g/l/kWh) of batch phase Aspergillus niger fermentations was unaffected by system geometry, at least up to concentrations of circa 15 g/1.

The cleaning of pipework from fluids of high viscosity is a significant problem in many food and personal care industries which can cause considerable economic and environmental impact. Three stages are identified in the cleaning of straight pipes; (i) a short core removal stage of product recovery, before water breaks through the filled pipe, (ii) the 1st cleaning stage (film removal stage) when there is a continuous wavy annular film on the wall, and (iii) the 2nd cleaning stage (patch removal stage) in which the material is present as patches on the wall. The product recovery stage is found to influence the overall cleaning process. Conducting product recovery at low temperatures and high flow rates cause the formation of a wavy wall layer which leads to more rapid subsequent removal. A two step CIP protocol is proposed to decrease the environmental impact of cleaning of a viscoelastic material (toothpaste) from pipework. Applying cold water in the 1st cleaning stage and hot water in the 2nd cleaning stage results in 40 % energy saving without affecting the cleaning performance significantly compared to traditional CIP protocols used in plants. Yield stress of deposits is the key effect on the cleaning of deposits. A new dimensionless number is explored. It is physically a ratio of flow energy to the yield stress of a deposit. It has collapsed cleaning time data onto a one curve for different deposits cleaned at different velocities. It can be used to predict cleaning times of deposits or identify the governing cleaning mechanisms in cleaning. It is found that the magnitude of pressure loss in flow can be used to quantify the flow and turbulence effect on cleaning and scale up lab scale data. The results show that although fluid mechanical removal is a complex process, cleaning time of deposits can be predicted by knowing its rheology and fluid mechanical parameters of cleaning fluid.

The local dynamics of sandwaves and their crest-shedding turbulent flows has received little mechanistic attention, unlike recent advances in allied fields such as bubbly shear flows. One main purpose of the present project is to address these questions of particle engagement and transport by transient large eddies in the free shear layer over sandwaves. Experimental studies were conducted on the trajectories of model particles over suitably scaled fixed bedforms in a purpose built flume. Three important results emerged. Firstly, trajectories of particles jetted over the crest fell into seven primary modes from short paths beyond the crest to extended downstream transport. Secondly, the vertical profiles of particle concentration exhibited peaks at crest elevation over the trough, comparing with recent field observations by (Soulsby, 1989). Thirdly, flapping excursions of the shear layer were found to enhance lee slope scour and probably account for the sediment clouds observed in Soulsby's field study, here further conjectured to result in sandwave washout at high flow velocities. Favourable comparisons with previous studies are described.

Cider and/or beer lees has normally either been used as low cost animal feed or been disposed of at great cost. A higher value use for the yeast was therefore sought. This has been developed with the use of environmentally friendly subcritical water extraction. Results have shown that the extract contains anti-oxidant activity using two separate anti-oxidant assays, with a large improvement in activity above a process temperature of 200 °C. This is due in large part to an increase in the concentration of phenolic compounds in the extract. As a result of this, a refined extract was produced using supercritical CO2 that improved anti-oxidant activity compared to the crude extract. The anti-oxidant activity of the 200°C and refined extract has also been demonstrated using the comet assay in cells with the performance of the extracts being comparable to that of Trolox. The rheological stability of a number of cosmetic formulations incorporating the extract has also been tested with 2 of the 4 formulations being stable. However, colour change issues have been observed with all four formulations tested. Overall, a novel and biologically effective extract has been produced using data from anti-oxidant assays to improve activity of the extract.

Proton Transfer Reaction - Mass Spectrometry (PTR-MS) is a soft chemical ionisation mass spectrometry technique frequently applied to measurement of volatile organic compound (VOC) abundance. The overarching aim of this thesis is to improve the quantification of compounds that have proved difficult or even impossible to separate or to quantify, through advanced understanding of the detection and ionisation mechanisms and developments in the instrumental design and operation of PTR-MS for deconvolution of mixtures. A new method for the preparation and use of diffusion tube methods as gas standards is reported. Detailed investigation of the ion-molecule reactions with chloroalkanes, chloroalkenes and other atmospherically important molecules, such as isoprene / 2-methyl-3-buten-2-ol, benzene / ethylbenzene / o,m,p-xylene and methyl vinyl ketone / methacrolein were undertaken to determine the ion- molecule reaction mechanisms, allowing quantification of isomeric species through understanding of the reaction products and novel approaches to the switching of the reduced electric field strength (E/n). The modification of instrumental parameters of PTR-MS were investigated further for the quantification of semi volatile compounds (SVOCs) and more specifically, polycyclic aromatic hydrocarbons (PAHs). Use of a radio frequency (RF) ion funnel and high temperature instrumentation allowed for sub nanogram limits of detection for many PAHs, including Benzo[a]pyrene.

<p> The increased presence of technology in all aspects of daily life makes computational thinking a necessary skill. Predictions say that the rising need for computational thinkers will be unmet by computer science graduates. An e-textile learning module, based on principles of constructionism, was designed as a method to develop computational thinking skills and encourage interest and confidence in the computing fields in both male and female graduate education students. The module leveraged the affordances of the LilyPad Arduino, a technology that allows for the creation of projects that integrate textiles and electronics without soldering. The creation of the learning module relied on design-based research methodologies and followed the use-modify-create principle for the included activities. Multiple data sources were analyzed using The Computational Thinking Rubric for Examining Students&rsquo; Project Work to examine artifacts and interactions for indications of computational thinking concepts, practices, and perspectives. Students participated in debugging activities and created their own projects as part of the learning module. Analysis of the learning module activities showed students using computational thinking concepts, engaged in computational thinking practices, and exhibiting computational thinking perspectives. During the coding process, several new computational thinking concepts, practices, and perspectives emerged. There was evidence of both an increase and decrease in confidence among the student participants. Improvements for the next iteration of the learning module were presented and the implications for the study of computational thinking explored. The study helps contradict the shrinking pipeline metaphor by showing that it is possible to encourage interest in computation in university students, not just middle-school students.</p><p>

<div>The present study evaluated the feasibility and social validity of using a wearable technology to detect anxiety for educational purposes. Twenty college student who planned to take a Graduate Study Exam (GRE) for attending graduate school were recruited to participate in the study. Each participant completed a practice GRE with quantitative and verbal reasoning sections. The participants were asked to complete a demographic questionnaire and State and Trait Anxiety Inventory before the practice exam. An acceptability questionnaire was administered after the practice exam to collect data on the social validity of the wearable technology. During the practice exam, the participants were asked to tap a button on the wearable device to report stressful incidents (SI) when they felt the exam questions were causing them to feel stressed. The participants’ heart rate and skin conductance data were collected and analyzed with the timing of their self-reported SI. The data indicated that significant heart rate changes were detected in 66% and 70% of the self-reported SI in the quantitative and verbal reasoning sections, respectively. The results indicated heart rate data could be used for short-term anxiety monitoring for educational purposes in the real classrooms. The social validity data indicated polarized results for the acceptance of an anxiety monitoring technology for educational purposes. Participants with higher familiarity with wearable devices in general reported the wearable device used in the study less distracting during the practice exams. Participants with higher levels of anxiety reported being less comfortable with their physiological signals monitored during the practice exams. Implications and suggestions for future research studies are discussed.</div>

This work contributes to the development of a micro-tubular solid oxide fuel cell (mSOFC) stack for use in a small unmanned aerial vehicle. Fuel cells offer cleaner, near-silent operation. Solid oxide fuel cells were chosen due to their higher efficiency and hydrocarbon fuel tolerance. Micro-tubular cells were chosen due to their simpler sealing requirements and stronger cycling properties. 250 W power is required, necessitating the use of many cells. Cathode manufacture was considered and various changes to current techniques suggested. Dip-coating was tested as an alternative to brush-painting. The acetone-based ink was unsuitable for dip-coating so a novel, cheaper, water-based ink was developed and a patent application registered. Cell power, transient and cycling performances were investigated. This transient work is a significant addition to the literature, improving understanding of mSOFC dynamic behaviour. Brush-painted cells take under half a second to adjust to current changes, without voltage overshooting. Dip-coated cells showed weaker performance, potentially due to lower porosity inhibiting mass transport. A six-cell module was built, using modelling to optimise manifold design, and its power and transient performance assessed. Interconnections present significant issues for mSOFCs. Despite power density decreasing with increasing diameter, fewer, larger tubes were used to reduce this problem. A new interconnection approach was developed, combining current techniques.

Abstract not available