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"Tuck, Christopher"
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Valorization of Biomass: Deriving More Value from Waste
2012
Most of the carbon-based compounds currently manufactured by the chemical industry are derived from petroleum. The rising cost and dwindling supply of oil have been focusing attention on possible routes to making chemicals, fuels, and solvents from biomass instead. In this context, many recent studies have assessed the relative merits of applying different dedicated crops to chemical production. Here, we highlight the opportunities for diverting existing residual biomass—the by-products of present agricultural and food-processing streams—to this end.
Journal Article
The Effects of Feature Sizes in Selectively Laser Melted Ti-6Al-4V Parts on the Validity of Optimised Process Parameters
by
Tuck, Christopher J.
,
Aboulkhair, Nesma T.
,
Phutela, Chinmay
in
Alloys
,
Corrosion resistance
,
Density
2019
Ti-6Al-4V is a popular alloy due to its high strength-to-weight ratio and excellent corrosion resistance. Many applications of additively manufactured Ti-6Al-4V using selective laser melting (SLM) have reached technology readiness. However, issues linked with metallurgical differences in parts manufactured by conventional processes and SLM persist. Very few studies have focused on relating the process parameters to the macroscopic and microscopic properties of parts with different size features. Therefore, the aim of this study was to investigate the effect of the size of features on the density, hardness, microstructural evolution, and mechanical properties of Ti-6Al-4V parts fabricated using a fixed set of parameters. It was found that there is an acceptable range of sizes that can be produced using a fixed set of parameters. Beyond a specific window, the relative density decreased. Upon decreasing the size of a cuboid from (5 × 5 × 5 mm) to (1 × 1 × 5 mm), porosity increased from 0.3% to 4.8%. Within a suitable size range, the microstructure was not significantly affected by size; however, a major change was observed outside the acceptable size window. The size of features played a significant role in the variation of mechanical properties. Under tensile loading, decreasing the gauge size, the ultimate and yield strengths deteriorated. This investigation, therefore, presents an understanding of the correlation between the feature size and process parameters in terms of the microscopic and macroscopic properties of Ti-6Al-4V parts manufactured using SLM. This study also highlights the fact that any set of optimized process parameters will only be valid within a specific size window.
Journal Article
Universal mobility characteristics of graphene originating from charge scattering by ionised impurities
by
Gosling, Jonathan H.
,
Tuck, Christopher J.
,
Wang, Feiran
in
639/766
,
639/766/119/995
,
Boltzmann transport equation
2021
Pristine graphene and graphene-based heterostructures can exhibit exceptionally high electron mobility if their surface contains few electron-scattering impurities. Mobility directly influences electrical conductivity and its dependence on the carrier density. But linking these key transport parameters remains a challenging task for both theorists and experimentalists. Here, we report numerical and analytical models of carrier transport in graphene, which reveal a universal connection between graphene’s carrier mobility and the variation of its electrical conductivity with carrier density. Our model of graphene conductivity is based on a convolution of carrier density and its uncertainty, which is verified by numerical solution of the Boltzmann transport equation including the effects of charged impurity scattering and optical phonons on the carrier mobility. This model reproduces, explains, and unifies experimental mobility and conductivity data from a wide range of samples and provides a way to predict a priori all key transport parameters of graphene devices. Our results open a route for controlling the transport properties of graphene by doping and for engineering the properties of 2D materials and heterostructures.
Graphene exhibits both extremely high electrical conductivity and electron mobility but an incomplete understanding of the underlying mechanisms so far limits potential applications in electrical devices. Here, the authors theoretically and experimentally investigate the role of charged impurities and optical phonons on the conductivity properties of graphene and establish a universal connection between the mobility and conductivity.
Journal Article
A facile one step route that introduces functionality to polymer powders for laser sintering
by
Tuck, Christopher J.
,
Machado, Fabricio
,
Krumins, Eduards
in
140/131
,
147/135
,
639/301/923/3931
2024
Laser Sintering (LS) is a type of Additive Manufacturing (AM) exploiting laser processing of polymeric particles to produce 3D objects. Because of its ease of processability and thermo-physical properties, polyamide-12 (PA-12) represents ~95% of the polymeric materials used in LS. This constrains the functionality of the items produced, including limited available colours. Moreover, PA-12 objects tend to biofoul in wet environments. Therefore, a key challenge is to develop an inexpensive route to introduce desirable functionality to PA-12. We report a facile, clean, and scalable approach to modification of PA-12, exploiting supercritical carbon dioxide (scCO
2
) and free radical polymerizations to yield functionalised PA-12 materials. These can be easily printed using commercial apparatus. We demonstrate the potential by creating coloured PA-12 materials and show that the same approach can be utilized to create anti-biofouling objects. Our approach to functionalise materials could open significant new applications for AM.
Polyamide-12 is the main polymer employed to produce 3D objects by laser sintering constraining the functionality of the items produced. Here, the authors report a clean and scalable approach for the functionalization of polyamide-12 particles, yielding materials that can be printed using commercial apparatus.
Journal Article
Targeting rehabilitation to improve outcomes after total knee arthroplasty in patients at risk of poor outcomes: randomised controlled trial
by
Stoddart, Andrew
,
Barker, Karen L
,
Hutchinson, James D
in
Arthritis
,
Arthroplasty (knee)
,
Clinical outcomes
2020
AbstractObjectiveTo evaluate whether a progressive course of outpatient physiotherapy offers superior outcomes to a single physiotherapy review and home exercise based intervention when targeted at patients with a predicted poor outcome after total knee arthroplasty.DesignParallel group randomised controlled trial.Setting13 secondary and tertiary care centres in the UK providing postoperative physiotherapy.Participants334 participants with knee osteoarthritis who were defined as at risk of a poor outcome after total knee arthroplasty, based on the Oxford knee score, at six weeks postoperatively. 163 were allocated to therapist led outpatient rehabilitation and 171 to a home exercise based protocol.InterventionsAll participants were reviewed by a physiotherapist and commenced 18 sessions of rehabilitation over six weeks, either as therapist led outpatient rehabilitation (progressive goal oriented functional rehabilitation protocol, modified weekly in one-one contact sessions) or as physiotherapy review followed by a home exercise based regimen (without progressive input from a physiotherapist).Main outcome measuresPrimary outcome was Oxford knee score at 52 weeks, with a 4 point difference between groups considered to be clinically meaningful. Secondary outcomes included additional patient reported outcome measures of pain and function at 14, 26, and 52 weeks post-surgery.Results334 patients were randomised. Eight were lost to follow-up. Intervention compliance was more than 85%. The between group difference in Oxford knee score at 52 weeks was 1.91 (95% confidence interval −0.18 to 3.99) points, favouring the outpatient rehabilitation arm (P=0.07). When all time point data were analysed, the between group difference in Oxford knee score was a non-clinically meaningful 2.25 points (0.61 to 3.90, P=0.01). No between group differences were found for secondary outcomes of average pain (0.25 points, −0.78 to 0.28, P=0.36) or worst pain (0.22 points, −0.71 to 0.41, P=0.50) at 52 weeks or earlier time points, or of satisfaction with outcome (odds ratio 1.07, 95% confidence interval 0.71 to 1.62, P=0.75) or post-intervention function (4.64 seconds, 95% confidence interval −14.25 to 4.96, P=0.34).ConclusionsOutpatient therapist led rehabilitation was not superior to a single physiotherapist review and home exercise based regimen in patients at risk of poor outcomes after total knee arthroplasty. No clinically relevant differences were observed across primary or secondary outcome measures.Trials registrationCurrent Controlled Trials ISRCTN23357609 and ClinicalTrials.gov NCT01849445.
Journal Article
The Impact of Additive Manufacturing on the Flexibility of a Manufacturing Supply Chain
by
Elmadih, Waiel
,
Tuck, Christopher
,
Alogla, Ageel Abdulaziz
in
3D printing
,
Additive manufacturing
,
Case studies
2021
There is an increasing need for supply chains that can rapidly respond to fluctuating demands and can provide customised products. This supply chain design requires the development of flexibility as a critical capability. To this end, firms are considering Additive Manufacturing (AM) as one strategic option that could enable such a capability. This paper develops a conceptual model that maps AM characteristics relevant to flexibility against key market disruption scenarios. Following the development of this model, a case study is undertaken to indicate the impact of adopting AM on supply chain flexibility from four major flexibility-related aspects: volume, mix, delivery, and new product introduction. An inter-process comparison is implemented in this case study using data collected from a manufacturing company that produces pipe fittings using Injection Moulding (IM). The supply chain employing IM in this case study shows greater volume and delivery flexibility levels (i.e., 65.68% and 92.8% for IM compared to 58.70% and 75.35% for AM, respectively) while the AM supply chain shows greater mix and new product introduction flexibility, indicated by the lower changeover time and cost of new product introduction to the system (i.e., 0.33 h and €0 for AM compared to 4.91 h and €30,000 for IM, respectively). This work will allow decision-makers to take timely decisions by providing useful information on the effect of AM adoption on supply chain flexibility in different sudden disruption scenarios such as demand uncertainty, demand variability, lead-time compression and product variety.
Journal Article
Additive manufacture of complex 3D Au-containing nanocomposites by simultaneous two-photon polymerisation and photoreduction
2017
The fabrication of complex three-dimensional gold-containing nanocomposite structures by simultaneous two-photon polymerisation and photoreduction is demonstrated. Increased salt delivers reduced feature sizes down to line widths as small as 78 nm, a level of structural intricacy that represents a significant advance in fabrication complexity. The development of a general methodology to efficiently mix pentaerythritol triacrylate (PETA) with gold chloride hydrate (HAuCl
4
∙3H
2
O) is reported, where the gold salt concentration is adjustable on demand from zero to 20 wt%. For the first-time 7-Diethylamino-3-thenoylcoumarin (DETC) is used as the photoinitiator. Only 0.5 wt% of DETC was required to promote both polymerisation and photoreduction of up to 20 wt% of gold salt. This efficiency is the highest reported for Au-containing composite fabrication by two-photon lithography. Transmission Electron Microscopy (TEM) analysis confirmed the presence of small metallic nanoparticles (5.4 ± 1.4 nm for long axis / 3.7 ± 0.9 nm for short axis) embedded within the polymer matrix, whilst X-ray Photoelectron Spectroscopy (XPS) confirmed that they exist in the zero valent oxidation state. UV-vis spectroscopy defined that they exhibit the property of localised surface plasmon resonance (LSPR). The capability demonstrated in this study opens up new avenues for a range of applications, including plasmonics, metamaterials, flexible electronics and biosensors.
Journal Article
Data sharing in clinical trials – practical guidance on anonymising trial datasets
2018
Background
There is an increasing demand by non-commercial funders that trialists should provide access to trial data once the primary analysis is completed. This has to take into account concerns about identifying individual trial participants, and the legal and regulatory requirements.
Methods
Using the good practice guideline laid out by the work funded by the Medical Research Council Hubs for Trials Methodology Research (MRC HTMR), we anonymised a dataset from a recently completed trial. Using this example, we present practical guidance on how to anonymise a dataset, and describe rules that could be used on other trial datasets. We describe how these might differ if the trial was to be made freely available to all, or if the data could only be accessed with specific permission and data usage agreements in place.
Results
Following the good practice guidelines, we successfully created a controlled access model for trial data sharing. The data were assessed on a case-by-case basis classifying variables as direct, indirect and superfluous identifiers with differing methods of anonymisation assigned depending on the type of identifier. A final dataset was created and checks of the anonymised dataset were applied. Lastly, a procedure for release of the data was implemented to complete the process.
Conclusions
We have implemented a practical solution to the data anonymisation process resulting in a bespoke anonymised dataset for a recently completed trial. We have gained useful learnings in terms of efficiency of the process going forward, the need to balance anonymity with data utilisation and future work that should be undertaken.
Journal Article
A Soluble ‘Ba(Ni-ett)’ (ett = 1,1,2,2-Ethenetetrathiolate) Derived Thermoelectric Material
by
Tuck, Christopher J.
,
Wildman, Ricky D.
,
Makarovsky, Oleg
in
Barium
,
Barium hydroxide
,
Characterization and Evaluation of Materials
2024
We describe the synthesis and characterisation of the first of a new class of soluble ladder oligomeric thermoelectric material based on previously unutilised ethene-1,1,2,2-tetrasulfonic acid. Reaction of Ba(OH)
2
and propionic acid at a 1:1 stoichiometry leads to the formation of the previously unrecognised soluble [Ba(OH)(O
2
CEt)]⋅H
2
O. The latter when used to hydrolyse 1,3,4,6-tetrathiapentalene-2,5-dione (TPD), in the presence of NiCl
2
, forms a new material whose elemental composition is in accord with the formula [(EtCO
2
Ba)
4
Ni
8
{(O
3
S)
2
C = C(SO
3
)
2
}
5
]⋅22H
2
O (
4
). Compound
4
can be pressed into pellets, drop-cast as DMSO solutions or ink-jet printed (down to sub-mm resolutions). While its room temperature thermoelectric properties are modest (σ
max
0.04 S cm
−1
and Seebeck coefficient, α
max
− 25.8 μV K
−1
) we introduce a versatile new oligomeric material that opens new possible synthetic routes for n-type thermoelectrics.
Graphical Abstract
Journal Article
Integrating High-Reliability Principles to Transform Access and Throughput by Creating a Centralized Operations Center
by
Tuck, Christopher R.
,
Carter, Kimberly F.
,
Echternach, Jeffrey M.
in
Adult
,
Aged
,
Aged, 80 and over
2018
High-reliability organizations (HROs) demonstrate unique and consistent characteristics, including operational sensitivity and control, situational awareness, hyperacute use of technology and data, and actionable process transformation. System complexity and reliance on information-based processes challenge healthcare organizations to replicate HRO processes. This article describes a healthcare organization’s 3-year journey to achieve key HRO features to deliver high-quality, patient-centric care via an operations center powered by the principles of high-reliability data and software to impact patient throughput and flow.
Journal Article