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‘Get the simple things right and the big things take care of themselves’ studies on brewing yeast, fermentation and draught beer : 1979-2025
No full textThe work reported here between 1979 and 2025, spans the heyday and decline of
brewing science in the UK. The brewing industry was in rude health until the
publication in 1989 of ‘Beer Orders’ by Monopolies and Mergers Commission which
removed the ‘tie’ between breweries and pubs. This removed large swathes of
profitability and began the long march to decline. Technical centres were downsized
or closed and by 2000 the ‘big six’ UK brewers had either ceased brewing or were
owned by brewing companies from the USA, Belgium and South Africa.
Two themes are discussed: brewing yeast and fermentation (Chapters 2-5) and
draught beer quality (Chapter 6). The guiding principle to both studies is to ‘get the
simple things right and the big things take care of themselves’. The studies on yeast
and fermentation were mostly performed at Bass, the biggest of the then ‘big six’ UK
brewers. Although commercially driven, there were opportunities to publish less
sensitive work. Indeed, the various brewing conferences around the world encouraged
this and brewing science flourished with unspoken competition between brewing
companies for publications of quality, impact and influence.
The flavour and aroma of beer is important. It should be consistent, balanced and
reflect the brand specification. The industry was in significant growth in the late 70s
and, consequently, new large scale fermentation processes were introduced. This had
an impact on the production by yeast of esters and higher alcohols during fermentation
which distorted the aroma of the beer. The work outlined in Chapter 2 sought to better
understand the synthesis of these metabolites and to be able to better control their
formation. In both instances, their synthesis reflected the need to balance the flux of
intermediary metabolic cofactors, acetyl CoA/CoA (esters) and NADH/NAD (higher
alcohols). Yeast does what it does for good metabolic reasons and not to please the
brewer!
Yeast is an important contributor to the distinctiveness of beer, with different strains
making different beers. A key part of Chapter 3 is the process that was developed to
assure the identity and microbiological quality of yeast that was periodically ‘supplied’
to the Bass breweries. It was ahead of its time using cryogenic long-term storage of
production yeasts and DNA fingerprinting to validate (blind) the identity of each strain.
Allied to this work, is a study of the genetic instability of a major production yeast used
in two breweries, separated by 280 miles and some 10 years apart. Other work
considers the introduction of ATP bioluminescence to validate in real time the cleaning
of brewery vessels. This was a cultural change as the checking of the effectiveness of
the clean was performed by process operators and not the ‘white coats’ from the
Quality department. Adoption of the technology and its delivery is now the norm in
global brewing industry. The final piece in this Chapter describes some opportunist
research that explored the unexpected metabolism by brewing yeasts of the sugar
alcohol, mannitol.
Brewery fermentations need to be efficient, requiring sufficient but not excessive yeast
growth. The work in Chapter 4 considers the role of small amounts of oxygen added
at the beginning of fermentation for the synthesis of sterols, a lipid class that
determines the extent of yeast cell division and growth. Evidence is presented that at the beginning of fermentation, the yeast cell is unable to transport exogenous sugars
and that the metabolic fuel for this process is provided by glucose from the breakdown
of the storage carbohydrate glycogen.
At the time, the efficiency of fermentation and its management was a major driver of
research in the brewing industry. Although much of the work in Chapter 5 was
developed in the laboratory, we were fortunate that elements were evaluated at a
production scale. Initial work explored the relationship between oxygen and yeast
growth. This demonstrated that yeast strains require the addition of an optimal level of
oxygen to achieve the required fermentation performance and efficiency. Excess
oxygen resulted in excess yeast growth and less ethanol formation. An innovative
approach evaluated at a plant scale considered a more direct approach with the
oxygenation of yeast. Regrettably, a change in the approach for beer taxation
undermined this work which was not progressed further.
Brewery fermentations are unusual in recycling yeast from one fermentation to the
next. This can pose problems, as yeast quality can become compromised. Chapter
5.3 describes a ‘warm cropping’ process where yeast is recovered (‘cropped) from
fermenter two days earlier than is usual. This approach improved the physiological
quality of the yeast which – in extensive series of production fermentations – resulted
in a step change improvement in quality metrics. Further work on the cropping process
considered the heterogeneity of yeast cell populations. The age profile (and
associated cell size) of individual cells was of interest together with their selection
during cropping and subsequent performance in brewery fermentations.
On leaving Bass - now Molson Coors - in 2004, brewing science in the UK was sadly
in decline. Consultancy called and I became a ‘portfolio professional’ doing a bit of this
and a bit of that. A part time role at Heriot-Watt University was enjoyable but after eight
years there was appeal in working closer to home and, if possible, doing some
research. A role at the University of Nottingham achieved both objectives. Although
funding for yeast research was difficult, a new direction loomed.
As a consumer, I was aware that the quality of draught beer can be variable and
occasionally poor. With previous experience at Bass of dispense technology coupled
with being a microbiologist, it made sense to develop a research programme into the
factors that impact on draught beer quality. These studies are reported in Chapter 6
and, like some of the yeast studies, benefit from taking the work out of the laboratory
into the ‘real world’.
Draught beer systems are invariably contaminated with non-pathogenic
microorganisms (yeasts and bacteria) that can grow in beer. Low levels are not a
concern but the quality (flavour, aroma, clarity) of draught beer becomes progressively
compromised with greater numbers of microorganisms which attach to surfaces in the
dispense system as biofilms. Microbial contamination is managed by hygienic
practices, primarily line cleaning where the system is flushed with dilute caustic
solution. This is the weak link as the process is tedious and the recommended weekly
clean can – in many accounts - slip to two weeks or more. Measurement of quality
using a ‘forcing test’ (Chapter 6.3) was used with samples from public houses (Chapter
6.4) confirming that beer quality ranged from ‘excellent’ through ‘acceptable’ to ‘poor
and ‘unacceptable’. Other work modelled biofilm attachment and growth by microorganisms in draught beer (Chapter 6.5). The microorganisms in different styles
of draught beer from multiple public houses in different cities and towns exhibited a
core microflora (e.g. Brettanomyces, Acetobacter) with some specific to individual
styles (Chapter 6.6). In a parallel study, microflora were inoculated into different
commercial lagers and found to vary in susceptibility to spoilage. Greater spoilage was
associated with beers of higher pH and nutrient availability (Chapter 6.7). In a similar
study, the susceptibility to spoilage of alcohol free and low alcohol beers was
evaluated. These beers were more spoilable (rate and extent) than conventional
‘alcoholic beer’. Although alcohol free beers (AFBs) may require tuning for effective
pasteurisation, a greater concern is their delivery in public houses using draught
dispense. With the growth of the sector, brand owners are increasingly keen to serve
their beers in this way as it is more profitable than with bottles or cans. This is a
concern with these beers being more easily spoilt by microorganisms which will
compromise quality. A very different concern is the absence of alcohol will allow the
growth of some contaminating pathogens in alcohol free beer which is a significant
concern for food safety. The recommendation that AFBs are dispensed by bespoke,
stand-alone dispense systems has had limited take up which suggests there is need
for other approaches to minimise this particular consumer risk
Broadband laser pulse pre-amplification and characterisation for petawatt-scale facilities
No full textThe amplification and characterisation of broadband near-infrared pulses in
Petawatt-scale laser facilities presents unique challenges not encountered at lower pulse
energies. This thesis research contributes to the development of two petawatt-scale laser
projects at the UK’s Central Laser Facility, with a focus on a front-end noncollinear
optical parametric amplifier (OPA) architecture and novel short pulse temporal
characterisation techniques. An OPA system of four stages was demonstrated in the
picosecond regime to amplify nanojoule seed pulses with a 160-nm bandwidth about
880 nm to energies of 1 mJ at 100 Hz. Compression of the picosecond front end was
implemented using a transmissive grating compressor with 50% efficiency and
optimised using a Fastlite DAZZLER acousto-optic programmable dispersive filter to
produce 16–17 fs pulses. A complete design for a nsOPA pre-amplifier was developed
for use at the Extreme Photonics Applications Centre, a 10 Hz short pulse petawatt
facility, in which a nanosecond OPA amplifier was constructed, showing a large initial
gain (×104
) over 750–850 nm, with a final performance intended to amplify from 10 µJ
to 1.5 J using barium borate and lithium triborate nonlinear crystals. A novel diagnostic
was developed that visualises, calculates, and compensates for beam angular dispersion
and was shown to have a precision of 1.4 nrad/nm. This result demonstrated simple laser
pulse manipulation of angular dispersion, and thereby pulse-front tilt, for optimal pulse
duration when focused, without adjustments of the large compressor gratings, which are
required in high-power laser facilities. The diagnostic was applied to an existing,
operational petawatt facility, VEGA, to record the angular dispersion in 13 different
locations throughout the beamline to highlight areas of improvement within the laser
alignment—specifically the compressor(s) and stretcher(s). This project substantially
contributed to the development of the EPAC system, which, once operational, will be a
world-leading user facility
Engaging older adults in cognitive activities through socially assistive robots and sensory feedback
No full textThis thesis investigates how the novel combination of socially assistive robots and sensory
feedback can foster engagement in cognitive activities for the older adult population. Cognitive decline is a natural part of ageing, and whether it arises from pathological or non-pathological origins, nonpharmaceutical methods can retain cognitive function and delay
cognitive decline. Namely, cognitive training and leisure-based cognitive activities can positively impact older adults’ cognition. While consistent long-term engagement is required to
attain the cognitive benefits, adherence has been identified as a common challenge for older
adults. Therefore, tools which can promote engagement in cognitive activities can benefit
the ageing population. This doctoral work employed validated user-centred methodologies to
investigate whether the unique combination of socially assistive robots and sensory feedback
could promote older adults’ engagement in cognitive activities.
This research began with a feasibility study with young adults and a usability study with
older adults, which both confirmed the potential for combining socially assistive robots and
sensory feedback to foster engagement in cognitive activities. This was followed by a Participatory Design workshop with older adults and therapists that identified concrete interaction
designs and themes for encouraging cognitive activity engagement. These results were integrated into a prototype, and its evaluation with older adults confirmed its effectiveness in
promoting engagement with cognitive activities. The subsequent study identified enhanced
performance and usability of engaging with a cognitive activity through a socially assistive
robot over a laptop, in addition to a preference for kinesthetic feedback over non-contact
cutaneous feedback.
This thesis further contributed a long-term experiment with eleven older adults to determine whether the promising results from the prior user-centred evaluations would promote
sustained engagement. Contrary to other robotic experiments, this study led to a consistent
level of engagement with the robot, and it was also preferred over typical interactions with
cognitive activities. Haptic feedback also enhanced engagement for visual-based activities
over the long term. The principal finding from this work is that the novel combination of
a SAR and sensory feedback can promote short- and long-term engagement in cognitive
activities for older adults, which has the potential to lead to benefits in cognition.
The thesis concludes with a set of guidelines for designing socially assistive robots and sensory feedback to foster cognitive engagement for older adults. This work, along with these
guidelines, can assist future researchers in human-robot interaction and human-computer
interaction to develop mechanisms for enhancing cognitive engagement for the ageing population moving forward.Engineering and Physical Sciences Research Council (EPSRC) funding Grant ID: EP/S023208/
Co-design of direct radiating array architectures and radio resource management for future broadband satellite communication systems
Full text linkOVER the past years, with the transition from broadcast to broadband satellite
communications, active direct radiating arrays have been seen as a key solution to guarantee
high performance in terms of capacity, flexibility and reconfigurability. Such configuration
gives a full flexibility in terms of coverage as beams can be steered along any desired direction
within the field-of-view. However, the hardware complexity of such antenna configurations is
unaffordable particularly in light of today’s on-board processors. The technological
requirements lead to unrealistic architectures, especially for GEO coverages where thousands
of radiating elements are needed. The proposed overlapping strategies with hybrid
beamforming guarantee very strong performance by mitigating some unwanted interfering
lobes which are particularly critical for satellite communications, while reducing the number
of control points. While optimizing the antenna architecture is a key for reaching very high
throughput, another challenge is the resource allocation. Frequency, time, beams, and power
management must be achieved in order to avoid latency during the communication and fulfil
the capacity demand. A full methodology is proposed in the thesis, considering a dual
optimization of both the antenna architecture and a new resource allocation strategy in terms
of throughput and time complexity
A roadmap to enhanced sustainability value in built environment : an optimised impact-framework
No full textImplementing this approach guarantees that the sustainability strategic goals and objectives of the client organisation are met and simultaneously addresses both environmental
objectives and the preferences and needs of the end-user. This research emphasises the
crucial necessity to equip sustainability consultants with the tools to make informed decisions that prioritise impactful sustainable solutions, rather than simply targeting high
accreditation scores and levels.
The research introduces an optimised framework for sustainable developments that constructs a decision-making matrix focused on achieving desired impacts, showcasing Net-Zero as an example theme. This framework integrates standards such as LEED and
the WELL Building Standards. Additionally, the framework aligns with the United
Nations Sustainable Development Goals (UNSDGs), striving for equilibrium among the
sustainability pillars. For practitioners involved in the credit selection process, the proposed framework offers a roadmap on how to optimise sustainability value by focusing
on the impact, while balancing both the business value of stakeholders and the comfort
and satisfaction of end-users. Uniquely, this research employs Backcasting as a novel
method within the sustainability credit selection framework, forecasting future impacts
and then interpret these projections retrospectively to refine credit selection strategies
for optimal sustainability results
Computational modelling of ruthenium catalysed C–H alkylation of heteroarenes
Full text linkA mechanistic study of the C–H alkylation of 2-phenylpyridine (2-ppy) using
alkyl halides and catalysed by [Ru(2-ppy)(MeCN)4]
+
has been carried out using density
functional theory (DFT).
A general mechanism has been proposed for the reaction of primary alkyl
halides, modelled as 1-bromopropane, in the presence of a carboxylate additive
(Chapter 3). Following C–H activation and cyclometallation via deprotonation by the
additive, an SN2 mechanism was identified for the C–Br activation step, leading to an
ortho-alkylated product after reductive coupling and product release. The latter has been
identified as the rate-determining step in catalysis.
Subsequently, the role of the carboxylate additive has been assessed by studying
the above reaction in its absence (Chapter 4). The results have shown that the substrate
can perform the deprotonation. It was found that the rate limiting-determining step in
catalysis becomes the formation of the C–H activation precursor, but the C–Br
activation is not significantly affected.
A complete mechanistic study of the C–X activation (with X = Cl, Br, I) of 1-
chloro-, 1-iodo-, 2-bromopropane and 2-bromo-2-methylpropane in the presence of a
carboxylate has also been performed (Chapter 5). While the nature of the halide does
not significantly influence either the mechanism or the selectivity of the reaction, it was
found that secondary and tertiary alkyl halides can follow a radical mechanism,
affording some or exclusive meta-alkylation.
Finally, the key results obtained in this thesis have been subjected to a
benchmark study, compared against the available experimental data (Chapter 6), and
GGA functionals have been proposed as the most appropriate method for this system
An experimental and numerical study of the kinetics of barium sulphate in flowing systems
Full text linkThe formation and deposition of mineral scales, such as barium sulphate (BaSO4) and
calcium carbonate (CaCO3), is a common problem in many industrial and life science
processes. This is caused by chemical incompatibility due to either the mixing of
incompatible aqueous solutions or due to changes of the physical conditions, usually
temperature and pressure. Many laboratory studies have been conducted using techniques
broadly classified into batch and flowing tests to understand the reaction and mechanisms.
In this study, we focused on the dynamic (kinetic) deposition of barium sulphate arising from
the mixing of 2 incompatible brines. The mechanism of barium sulphate (barite) deposition is
often assumed to be a one-step reaction in which the ions in the bulk fluid directly deposit
onto a surface. However, there is strong evidence in the literature that barium sulphate may
deposit through an intermediary nanocrystalline phase which we refer to as BaSO4(aq) in this
work. This initial nucleation species or nanocrystalline material (BaSO4(aq)) may remain
suspended in the aqueous system and hence may be transported through the system before it
ultimately deposits on a surface
In this work, we have formulated a barite formation/deposition model which includes both of
these mechanisms noted above, i.e. (i) barite formation in solution of a nanocrystalline
precursor which may be transported and deposited at an interface and (ii) the direct kinetic
deposition of barite from the free ions in solution.
The kinetic approach is most important in flowing conditions, since the residence time in a
given part of the macroscopic system (e.g. in a pipe or duct) may be shorter than the time
required to reach the full equilibrium state of the system. A CFD study is carried out by solving the Stokes equations to accurately model the local
residence time, species transport, and calculate the hydraulic and mass transfer layers.
Geometry alteration due depositing barite is also an important phenomenon to consider and
model in a flowing system. This is rarely done in mineral deposit calculations, especially with
a full kinetic deposition model, but it is included in our model. The geometry change affects
both hydraulic and mass transport layers in the vicinity of the depositing surface and may
often change the deposition regime in terms of the balance of dominant mechanism which
applies. The effect of geometry change on the local residence time is investigated through
performing a ramping up of the flow rate and explicitly deforming the geometry as the
deposition occurs.
We also performed and report experiments on two levels to gain information on the kinetics.
First, we studied the kinetics of incompatible brines using batch tests. Second, we developed
a laboratory experimental flow cell that enabled us to (i) use different flow geometries
through 3D printing, (ii) visualise the deposition process as it happens, and (iii) understand
the rates of the reactions by analysing the effluent from the system. We used three different
categories of geometries including a (i) simple flow channel, (ii) simple constrictions with
different configurations to enforce different mixing regimes, and (iii) more complicated
geometry with different constriction sizes. This allowed us to investigate the hypothesis
developed in the modelling work. The visual findings from laboratory experiments show the
deposition growth happens in the normal direction of the flow, and as the local residence time
reduces, the deposition tends to move further down the line. This is true in all three different
geometries investigated, showing the concept of the diffusion penetration length.
Our results from the modelling and experimental work, show that in the laminar flow regime,
the extent of deposition on a surface is limited by the diffusion penetration length (δ) referred
to above. This means that there will be more deposits at lower flow rates, where the diffusion penetration length is larger. In this case, since the diffusion penetration length is relatively
larger, the deposition mechanism will be kinetics-limited. As the deposition reduces the flow
path cross-section area near the inlet vicinity, the velocity increases. Thus, the hydraulic layer
becomes smaller, resulting in a smaller diffusion penetration length, which causes the
deposition location to move towards the end of the flow path, where the velocity is still lower.
In this case, since the diffusion penetration length is relatively smaller, the deposition process
will be more transport-limited. The results of this study have the potential to contribute to the
development of more effective strategies for preventing scaling in a wide range of industrial
processes
Developing novel 3D bioprinting techniques to create pancreatic cancer models
No full textCancer is a leading cause of death worldwide, with pancreatic ductal adenocarcinoma (PDAC)
having the lowest survival rates among all cancers, which have not improved in the past 50
years. PDAC tumours are characterised by a stiff, fibrotic stroma, which contributes to the
cancer’s aggressiveness and chemoresistance. Over the past decade, 3D bioprinting techniques
have gained popularity for their potential to create complex, biomimetic 3D in vitro models,
which recapitulate native tissue responses. However, developing 3D bioprinting techniques
requires addressing several challenges, primarily bioink biocompatibility and printability, as
well as long-term cell survival and behaviour.
In this present study, a novel 3D bioprinting method was developed using droplet-based
bioprinting technologies. Optimisation studies of bioprinting parameters demonstrated that
using an electromagnetic droplet (EMD) printhead, droplets of cell-laden GelMA bioinks can
be extruded with accuracy and precision. Additionally, two different support materials were
explored to deposit the droplets into: a gellan gum granular gel suspension medium and pure
Matrigel. Both methods showed that by adjusting the printing conditions, such as bath
temperature or extrusion pressure, the size and definition of the hydrogel droplets can be
controlled. Furthermore, this method enabled multilineage cell patterning, the Matrigel-based
constructs demonstrating enhanced cell viability, proliferation and functional activity. Lastly,
Matrigel was combined with a low-temperature gelation GelMA formulation to increase its
mechanical properties and offer a more robust microenvironment without losing its inherent
biocompatibility and support for cellular functions.
Despite some remaining limitations, such as achieving high resolution printing and scalability,
this novel method offers a unique tool for creating Matrigel rich 3D bioprinted cancer models.
Its customisation and reliability make it an appealing approach, which can be adapted to a
variety of tissues and pathophysiological conditions. Further development of this method could
transform it into a powerful tool in the 3D bioprinting field
Underwater visual acoustic SLAM with sensor calibration
Full text linkUnderwater environments present significant challenges for visual Simultaneous Localization and Mapping (SLAM) systems due to limited visibility, poor illumination,
and the sporadic loss of structural features in images. To address these issues, this
thesis focuses on underwater SLAM by fusing data from a Doppler Velocity Log
(DVL), stereo cameras, and Inertial Measurement Unit (IMU) within a graph optimization framework. Additionally, we propose an extrinsic and DVL transducer
calibration algorithm that estimates the extrinsic parameters and DVL transducer
orientation without requiring additional setups. Furthermore, a novel observability-aware, entropy-based active calibration method is introduced to actively search
for the next optimal poses for reliable calibration. Extensive experimental results
demonstrate that our proposed SLAM system surpasses state-of-the-art underwater
and visual-inertial SLAM systems in terms of localization accuracy and robustness,
and highlight the precision of our calibration algorithm
Understanding autistic people's lived experiences of employment
Full text linkAutistic workers face significant rates of unemployment, and those that do achieve
employment often face unsuitable environments built upon discrimination and challenges.
This thesis explores the lived experiences of autistic workers and interprets these using the
Social Relational Model of Disability (SRMD) to explore the disablement that autistic
workers experience.
Across three studies, this thesis uses qualitative methods and analyses to explore
autistic workers experiences from both the autistic workers and employers perspectives. The
three studies include a qualitative evidence synthesis of a systematic review (study 1), a
template analysis of interviews (study 2 part 1), and reflexive thematic analysis of interviews
(study 2 part 2) and a reflexive thematic analysis of interviews and focus groups with
employers (study 3).
The findings of this thesis illustrate the value of autistic workers perspectives, as new
insights are uncovered into the inappropriateness of disclosure and adjustment requesting
processes and the additional labours that autistic workers feel forced into performing.
Through the SRMD, autistic workers lived experiences reveal the disablement of the
workplace that is enforced through socially created and environmentally implemented
barriers that exploit the individual’s impairment effects. This disablement is further enforced
by psycho-emotional dimensions that lead to the workers exhausting themselves to meet the
expectations set by themselves and their workplace
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