The Postgraduate Institute was developed through a strategic partnership between NPL, the UK's National Measurement Institute and a BEIS partner organisation, and the University of Strathclyde and the University of Surrey, two leading academic institutions. The vision for the PGI is to become the Number One institute for postgraduate research and training in measurement science and its application to physical, engineering, biological and chemical sciences in the UK. The PGI aims to lead on the development of measurement experts who can benefit industry and wider society.

The PGI is currently partnered with over 35 higher education institutions and many industry partners. We have around 200 postgraduate researchers producing top quality research spanning many scientific disciplines – from manufacturing and life sciences to data and the environment. The discoveries they are making contribute significantly to the UK's position at the forefront of innovation in measurement science.

Telephone: 020 8977 3222 Email: [email protected] Website: www.npl.co.uk/pgi Twitter: PGImetrology Instagram: pgimetrology

Urgent Contacts during Conference If you have questions or queries for the Committee, please do not hesitate to contact us. Email: [email protected] Phone: 077750 30265 or 079765 18807

Welcome Letter from the Conference Committee

We are delighted to hold the 4th annual PGI Conference at NPL this autumn. After the success of previous years, we are looking forward to opening the conference to PGI students and supervisors, together with other delegates from academia and industry, and showcasing this year’s programme which is full of science, engineering and measurement talks, plus an all-new session on career development opportunities.

With the growth of the PGI over recent years, this is a fantastic opportunity for all our students to get involved and flourish in the experience of attending, presenting, organising and networking at a conference. The opportunity for the PGI to create and develop links with academia and industry has proven valuable each year, and we are sure that this year will be the same.

We would like to welcome you to this year’s conference and wish everyone an enjoyable and worthwhile few days at NPL.

Sponsors The committee would like to thank our sponsors for their generous support.

Gold Sponsors

National Physical Laboratory

Institute of Physics

SEPnet

Anatune

Elekta

Silver Sponsors

Henry Royce Institute The Henry Royce Institute is the UK’s national institute for advanced materials research and innovation. With its Hub at The University of Manchester, the Royce is a partnership of nine leading institutions – the universities of Cambridge, Imperial College London, Liverpool, Leeds, Oxford, Sheffield, the National Nuclear Laboratory, and UKAEA. The Institute’s aims are to undertake world-class research in materials science; to work with industry to accelerate the commercialisation of materials research for economic and societal benefit; and to train the next generation of materials scientists and engineers to tackle some of our most pressing global challenges

Institution of Engineering Technology As the IET, we inspire, inform and influence the global engineering community to engineer a better world. Innovative research is essential to develop technologies that make better sense of our world and solve the challenges that matter. We support researchers to help share and develop new thinking through publishing research in our books and journals and curating essential engineering intelligence through Inspec, our globally renowned database for engineering and physics. This year, we are pleased to announce the full release of Inspec Analytics. This dynamic new research intelligence tool exposes key relationships between institutions, authors, articles and concepts to provide precision analytics through new views and functionality. Inspec Analytics allows researchers to stay up-to-date with emerging topics in their field, find collaborators, source relevant resources for literature reviews and select the best place to publish their research. Our journal IET Science, Measurement and Technology publishes papers in science, engineering and technology underpinning electronic and electrical engineering, nanotechnology and medical instrumentation. The emphasis of the journal is on theory, simulation methodologies and measurement techniques. Find out more about submitting your research at: Ietdl.org/iet-smt. www.theiet.org/publishing

M-Solv M-Solv Ltd is an Oxford, UK based company, which was established in 2007 to be the UK technology development centre for CN Innovations (CNI); an over 10,000 people strong company in China. Originally M-Solv developed and supplied laser tooling to CNI to enable them to become a major leading supplier of capacitive touch screens for use in smart devices such as smartphones, tablets, wearables and computers. Over the last decade, M-Solv has become a world leader in the development of advanced manufacturing methods and tools, for next generation printable electronics. Through its R&D, M- Solv has generated over 100 patents in additive and subtractive manufacturing which are currently utilized in a plethora of applications. Energy harvesting/storage, biosensing, OLEDs, smart windows and flexible smartphones are only few of the markets it serves. M-Solv offers a full suite of capabilities, from initial research and development (contract R&D), design and build of mass-production tools through to manufacture of printed electronics devices. It is also an active participant in a series of publicly funded R&D projects under Horizon 2020, EU flagship initiatives and Innovate UK.

National Instruments NI (ni.com) develops high-performance automated test and automated measurement systems to help you solve your engineering challenges now and into the future. Our open, software-defined platform uses modular hardware and an expansive ecosystem to help you turn powerful possibilities into real solutions. Researchers are driving time-critical, ambitious innovation while addressing grand engineering challenges in the broad areas of transportation, wireless communications, energy and climate change. Across each of these application areas, researchers need to easily acquire measurements, scale to complex multidisciplinary systems, and rapidly prototype a scalable solution. NIs tools for high accuracy and high precision data acquisition is central to accelerating researcher innovation by providing the technology and support to prototype systems, publish findings and secure funding.

National Nuclear Laboratory Grounded in robust science and decades of experience, National Nuclear Laboratory (NNL) is the authoritative voice in the UK and beyond for technological development within the nuclear power sector. Our unparalleled understanding of the science, challenges and opportunities makes us an unrivalled authority and partner in the field, providing experts, technologies, and access to cutting-edge facilities to organisations around the world. Harnessing potential technologies and translating them into to industry-ready solutions means our pioneering approach spearheads international improvement and technological progress.

The Technology Partnership TTP is an independent technology company where scientists and engineers collaborate to invent, design and develop new products and technologies. Working across a wide range of industries – from healthcare, to sensors, industrial technology, and aerospace & defence – we tackle some of the most challenging scientific problems, delivering breakthrough solutions that have a world-wide impact. As a company, we value freedom and ideas; everyone within TTP has the space to grow and challenge themselves on a daily basis and we consider a PhD to provide someone with invaluable experience. As such, we have a long background of welcoming people into TTP from academia; we offer permanent consultant positions, along with internships for anyone interested in gaining an insight into industry during their studies. If you are curious about the opportunities joining a technology consultancy presents, then please visit our website, www.ttp.com, or else feel free to get in touch with any questions ([email protected]).

Venue and Registration

The Venue – National Physical Laboratory

Address: National Physical Laboratory, Hampton Road, Teddington, Middlesex, TW11 0LW

Directions Trains from London Waterloo runs regularly to Teddington Station (southeast corner on the map). Buses 33, 281, 285, 481, R68 and X26 serve Teddington, of which 285 (slow) and X26 (fast) connect Teddington with London Heathrow Airport. The stops are marked as blue squares. The entrance to NPL is on Hampton Road.

Registration and Arrival Conference registration is between 0930 and 1000 at Reception. If you are giving an oral presentation, please either submit your slides to the Committee at [email protected] by 4 November (preferred option), or bring them to the Auditorium on a USB stick during the break before the session you are presenting starts. The accepted file formats are .ppt, .pptx and .pdf. We encourage the use of one central machine for smooth transition between speakers. For posters, we will be providing poster stands. Please set your posters up at least before the poster sessions begin.

Photography Photographs will be taken during the course of the event, and they will be used for publicity and marketing purposes. If you would not like to be featured, please inform the Committee.

Wi-Fi The venue has eduroam for those who can access it. Otherwise, there is guest Wi-Fi available (network name: NPL-Guest). Once you are connected to the network, please follow the on-screen instructions.

Programme

Day 1 (06/11/2019) Location

0930 Arrival, Registration and Exhibits Reception

Opening Session

1000 Welcome: Richard Burguete; National Physical Laboratory Auditorium

Session 1: Enabling a Stronger Society Chair: Lewis Hill

1015 Keynote: What has metrology ever done for me? Auditorium Graeme Reid; Science and Research Policy, University College London

1045 Developing characterisation measurements for quantum key Auditorium distribution Sophie Albosh; University of York

Seeing sustainability from space using Earth observation data to populate sustainable development goal indicators Ana Andries; University of Surrey

The myriad applications of microresonators Michael Woodley; Heriot-Watt University

Accelerated ageing of polymer composites and the effect of moisture absorption on mechanical and chemical properties Jasmine Bone; University of Surrey

Poster Session 1 Chair: Minal Patel

1145 1-minute Introduction Auditorium

1200 Poster Viewing Upstairs - Foyer

1230 Lunch and Poster viewing continued Reception

1315 Conference Photo Reception

Session 2: Sustaining Our Environment Chair: Emma Braysher

1330 Keynote: Measurement Scientists and Sustainability Auditorium Chris France; University of Surrey

1400 Using Isotopic Signature of Methane in Budget Estimation Auditorium Alice Drinkwater and Edward Chung; University of Edinburgh

Modelling Energy Demand response using long-short term memory neural networks Jose Mesa Jimenez; Brunel University London

Mobile Air Quality Sampling in London UK Geoff Ma; University of Cambridge

Geo-polymer based stabilisers as an alternative to traditional stabilisers for flexible pavement construction Hadi Abba; University of Surrey

Poster Session 2 Chair: Edward Chung

1500 1-minute Introduction Auditorium

1515 Poster Viewing Upstairs - Foyer

1545 Coffee Reception

Session 3: Creating Impact on Health Chair: Ben Webster

1600 Keynote: The Importance of Metrology in the Application of Auditorium Medical Imaging to Drug Development Fred Wilson; Experimental Medicine Imaging, GlaxoSmithKline

1630 Laser Desorption – Rapid Evaporative Ionisation Mass Auditorium Spectrometry Platform for Tissue Imaging Daniel Simon; Imperial College London

Validation of texture analysis in CT imaging Christopher Green; University of Surrey

Raman metrology for live cell imaging Caitlin Thomson; University of Strathclyde

Implantable ultra-flexible bioelectronic mesh: reinvention of the cardiac pacemaker Danielle Cox-Pridmore; University of Surrey

Closing Session

1730 Voting and Closing Remarks Auditorium

1800 Close Day 1 Auditorium

1845 Drinks Reception and Conference Dinner Park Hotel

Day 2 (07/11/2019) Location

0930 Registration and coffee Reception

1000 Welcome: Paddy Regan; University of Surrey, National Physical Auditorium Laboratory

1015 Scene setting: Planning your career – getting the most out of today Auditorium Vishanti Fox; Institute of Physics Veronica Benson; South East Physics Network

1045 Keynote: The physics of imaging and why it matters. A journey Auditorium from 1.8 to 310.2K Phil Marsden; Unitive Design and Analysis

1115 Keynote: Impact through science Auditorium Josephine Bunch; National Physical Laboratory

1145 Employer Elevator Pitch (10 x 5mins) Auditorium Led by Veronica Benson, South East Physics Network

1245 Networking Lunch Reception

1345 Career Panel (10 x 3 mins) Upstairs Led by Vishanti Fox; Institute of Physics breakout room

1415 Break out into the Global Café (10 x 9mins) - refreshments Upstairs provided breakout room

1545 Reflective Practice (60mins) Auditorium Led by Amy Pearce; Institute of Physics

1645 Closing Remarks Auditorium

1700 Depart

Posters 1 Numerical methods for efficiently solving fractionally damped wave equations Katie Baker; Herriot-Watt University 2 Modelling and simulations of energy storage devices Joshua Bates; University of Surrey 3 A transfer and scattering matrix model of the NPL plane mirror differential interferometer Angus Bridges; Cranfield University 4 Fast-neutron induced fission studies for Nuclear Data measurements Rhiann Canavan; University of Surrey 5 Is urban air quality improving? Understanding trends in combustion particles. Krzysztof Ciupek; King’s College London 6 Design and Development of an X-ray Interferometer for Length Metrology Declan Cotter; University of Cambridge 7 Fibre-Optic pH Sensor Based on Silver Nanoparticles for Harsh Environments Shaon Debnath; University of Strathclyde 8 Towards All-Optical Computing Leonardo Del Bino; Heriot-Watt University 9 Extension of Coupled Mode Equations Describing Parametric Amplification Tom Dixon; Royal Holloway, University of London 10 Uncertainty quantification in unsupervised learning David Fernandes; University of Bath 11 Proof of concept investigation for in-vivo verification of microbeam radiotherapy using high resolution pixelated detectors Sam Flynn; University of Birmingham 12 Can SPECT Resolution Be Considered Invariant in Partial Volume Correction? Rebecca Gillen; University College London 13 Interlaboratory evaluation of MALDI and DESI MSI in the CRUK Grand Challenge programme Melina Kyriazi; Imperial College London 14 Determining the level and location of functional groups on few-layer graphene and their effect on the mechanical properties of nanocomposites Elizabeth J. Legge; University of Surrey 15 Preliminary Field Trial of CHAFF: CubeSat Hyperspectral Application For Farming Callum Middleton; University of Surrey 16 Automatic Detection of Canine Soft Tissue Sarcoma Using Transfer Learning Algorithms Ambra Morisi; University of Surrey 17 Development of Cellular Metabolomics Catherine Munteanu; Imperial College London 18 Radiotherapy MLC Upstream Leaf Edge Detection Using Lassena Large Area MAPS Jordan Pritchard; University of Bristol 19 Different Deep Learning Loss functions for grading Mast Cell Tumors using a weakly imbalanced histopathological dataset. Taran Rai; University of Surrey 20 Scope and limitations of Nuclear Magnetic Resonance techniques for characterisation and quantitation of vitamin D in complex mixtures Cameron Robertson; Kingston University 21 Investigating Biological Response of Combined Radiation and Magnetic Field Exposures with Nanoparticle Contrast Agents Emily Russell; Queen’s University Belfast 22 Power Quality Analysis in 25 kV 50 Hz AC Railway System Networks Yljon Seferi; University of Strathclyde 23 Large Scale Inference and Optimal Sensor Placement with Applications to Environmental Monitoring Louis Sharrock; Imperial College London 24 Beam Profile Investigation of an Optoelectronic Continuous-Wave Terahertz Emitter Jessica F. Smith; University of Surrey 25 Characterization of Hypoxic Organoid System for Radiation Response Studies of Pancreatic Ductal Adenocarcinoma Gabrielle Wishart; University of Surrey 26 Development of Hybrid Quantum Interference Devices for NMR Dan R. M. Woods; Royal Holloway, University of London Totem Entries for the Photo Competition

Social Events 1. Conference Dinner (Day 1) The Conference dinner will be held on the evening of the first day of the conference. The venue is the Park Hotel (blue dot). It includes a three-course meal and a cash bar is available. Dress code is smart casual. The awards for the oral and poster presentations will be given during the dinner.

Address: 19 Park Road, Teddington, TW11 0AB Drinks reception: 18:45 Dinner: 19:30 Thanks to entertainment provided by DJ Queen Bee and Science Magician Jack Lenoir

2. Post-conference For those who are not in a hurry to travel, there will be a post-conference pub outing. Details to follow.

Keynote and Guest Speakers

Key KN - Keynote SL - Session Leader CP - Careers Panel EP - Employers’ Pitch

Graeme Reid; University College London KN

Professor Graeme Reid is Chair of Science and Research Policy at University College London. He is a member of the Council of Research England.

He has spent most of his career at the interface between science and Government, having worked in the Business Department, the Cabinet Office and HM Treasury and before moving to UCL.

Graeme was specialist advisor to the House of Lords Science and Technology Committee during their extensive inquiries into Brexit and, more recently, industrial strategy. He is a member of the Government’s High Level Group on EU Exit, Universities, Research and Innovation. He has led research and innovation policy reviews for the Scottish Funding Council and the Welsh Government.

He is Chair of the Campaign for Science and Engineering, a Trustee of the Association of Medical Research Charities and strategic advisor to the National Centre for Universities and Business.

Graeme began his career at the National Engineering Laboratory. He has a BSc in Physics and a PhD in Mechanical Engineering. He is a Fellow of the Royal Society of Edinburgh, Fellow of the Institute of Physics, Fellow of the Institution of Engineering and Technology and a Chartered Engineer.

Chris France KN

Chris France started his career in biomedical measurements and went on to make sensors and instruments using optical fibres. As an early career academic he was involved in the development of an MSc in Industrial Measurement Systems which was co-taught by colleagues at the NPL. In the wake of the Rio Earth Summit (ask your parents) he was tempted into what was then the novel world of sustainability. Over 25 years he has worked with companies and policy- makers to make systems sustainable. Of relevance to this audience, Chris ran the EPSRC’s longest running Doctoral Training Centre where all researchers carried out their work based at the premises of their sponsor organisation. Latterly, he was founder Director of the Doctoral College at the University of Surrey.

Fred Wilson KN

Director, Imaging Physics; Clinical Imaging; GlaxoSmithKline. Specialist in Medical Imaging and Physiological Measurement Biomarkers with over 15 years experience encompassing the pharmaceutical industry, UK National Health Service and industrial R&D. A track record in strategy development and directing successful collaborations between academia and industry. Areas of interest include: Medical Imaging, Physiological Measurements (including EEG), Applying imaging/ physiological measurement biomarkers to decision-making in drug development.

Phil Marsden; Unitive Design and Analysis KN, CP

Phil Marsden received his PhD in 2001 from the Optoelectronics Research Centre, Southampton for work on electron spin relaxation in III-V semiconductors. His core interests lie in imaging and sensing in medical physics, specifically in the realms of broad spectrum, X-ray and charged particle imaging. His wider interests remain in the world of photo-detection in semiconductors in clinically-relevant environments, at the extremely low light level limit and for quantum information. Phil has been in the commercial world since 2005, initially developing imagers for the motion picture industry and subsequently in MedTech. His expertise is the design of medical devices and medical device subsystems in regulated environments.

Josephine Bunch; National Physical Laboratory KN

Professor Josephine Bunch is a Principal Research Scientist and Co- Director of the National Centre of Excellence in Mass Spectrometry Imaging (NiCE-MSI) at NPL and Chair of Biomolecular Mass Spectrometry at Imperial College London. Josephine is an NPL Fellow and leads research and metrology in MALDI and ambient mass spectrometry imaging within NiCE-MSI. She is currently leading a Cancer Research UK Grand Challenge programme. Josephine completed a PhD in mass spectrometry imaging at Sheffield Hallam University, sponsored by Pfizer Global R&D (2005). Josephine has expertise in a range of mass spectrometry imaging techniques and has published 55 articles on mass spectrometry imaging of lipids, drugs, proteins, peptides and metabolites using a range of dedicated mass spectrometry techniques. Josephine's group comprises a multidisciplinary team of physicists, chemists, computer scientists and biomedical scientists.

Veronica Benson; South East Physics Network SL

Veronica has a degree in Modern Languages from University of East Anglia and postgraduate qualifications in education, careers guidance and organisational behaviour. Following a short time in teaching, Veronica became a director of a conference company in London sourcing speakers and building contacts in the property, finance and legal industries. She went on to set up an education charity and alumni association for the real estate department at the University of Reading working with employers, supporting Masters students, raising funds and organising events. More recently she worked as South East Project Manager for WISE (women in science and engineering) running careers workshops for STEM women graduates and working with STEM employers and university departments to change culture and support women’s career progression. Prior to joining SEPnet Veronica led a National HE STEM project on the benefits of placements for undergraduates. Veronica joined SEPnet as Director of Employer Liaison in September 2012 where she manages an employer engagement programme for physics undergraduates and postgraduate research students which includes industry placements, career panels and employer workshops.

Vishanti Fox; Institute of Physics SL

Vishanti has worked for the Institute of Physics for over 15 years. Her current role focuses on supporting members, particularly undergraduates, apprentices and postgraduates, to increase their awareness of the broad range of career opportunities that qualifications in physics and experience gained in physics-based employment can open. In partnership with member groups and leading national bodies, Vishanti facilitates the organisation of careers events, the production of guidance material, supports and engages with careers advisers, and works directly with employers to interact with early career members. She is also responsible for providing online professional development opportunities for members.

Amy Pearce; Institute of Physics SL

I am currently responsible for managing the Institutes 6 professional registers, Chartered Physicist, Chartered Engineer, Registered Scientist, Incorporated Engineer, Registered Science Technician and Engineering Technician. This includes promoting professional development and the requirements for maintaining professional registration through CPD. Part of my role involves liaising with our Accredited Company Training Schemes and working with them to make the scheme a quality product which ensures those on the schemes are on a clear pathway to professional registration. I work closely with the Accreditation and Professional Development Manager and we are responsible for the maintenance of the Chartered Physicist standards and I also liaise with both the Science Council and the Engineering Council to ensure our processes are in line with their standards.

Katie Atkinson; Allen & Overy CP, EP

Katie studied at the University of Cambridge, graduating with an MSci in physics and a PhD on flexoelectricity in liquid crystal materials for display devices. Katie remained at Cambridge to undertake a postdoctoral position working on polymers for coronary stents. Katie then moved into industry and worked for Jaguar Land Rover in the Department of Materials Engineering, where she qualified as a Chartered Engineer. Whilst working in industry, Katie developed an interest in IP law. She is now working as a trainee solicitor at Allen & Overy and is currently working in the patent litigation team.

Adam Bozson; Babylon Health CP

Adam is a Machine Learning Scientist with Babylon Health. Babylon employs over 1600 scientists, clinicians, mathematicians and engineers. The team has been recruited from over sixty countries to work on putting an accessible and affordable health service in the hands of every person on Earth.

Adam recently completed his PhD in particle physics at Royal Holloway, working on the ATLAS experiment at the LHC. There he focused on developing statistical data analysis methods and tools with Gaussian processes, in addition to the reproducibility and reinterpretation of experimental results.

At Babylon, Adam researches representation learning, continuous time series, graphical models, and NLP. He is an active contributor in the ML research community. He is also interested in AI ethics and the wider impact of increasing automation.

Samuel Elegbede; WSP EP

Samuel is a multi-award-winning Telecommunication and Control systems engineer with a background in Electronic and Electrical Engineering. He focuses on, designing and presenting innovative SMART solutions to clients.

Samuel has been involved in some key railway project in the UK such as HS2 (Euston, Old Oak Common, Curzon Street stations) and Crossrail Paddington station. He is a technology savvy and passionate about how technology can influence the UK transportation sector.

Samuel is also an ambassador with the Association for BME engineers, where he provides support and encourages underrepresented groups to build a career in engineering.

Tony Gibbs; National Instruments EP

Tony Gibbs is responsible for managing the relationship between NI and six research and academic institutions including UCL, Imperial, University of Oxford and the University of Southampton. Targeting significant business potential, this involves the strategic alignment of the NI Platform, new products, solutions, and services to meet their unique needs.

Since joining NI in 1997, Tony managed both the Inside Sales and Customer Service departments. Tony has also spent time as a Technical Support Engineer, teaching certified LabVIEW courses and directly supporting customers.

Prior to joining NI, Tony spent 14 years in industry holding number of technical roles, such as Test Engineer, Manufacturing Engineer and Project Manager. He started his engineering career as an Apprentice Instrument Maker at BAE Systems.

Nathan Hawkins; Anatune EP

I joined Anatune in 2014 as an Account Manager and Anatune’s Bioscience and Biotech Market Specialist (having previously run a Metabolomics core facility since 2000).

As a market specialist, my role is to engage with key opinion leaders in the life sciences to understand their measurement science challenges. We then collaborate with academic and industry partners to develop innovative solutions (that work) to meet them. This can only be done through teamwork involving Anatune (Applications and Product Development chemists) and our partners (Syft Technologies, Agilent Technologies, GERSTEL) to develop, build and test a solution and our customers.

In the life sciences, Anatune have collaborations ranging from agricultural chemistry, bio-analysis, biopharmaceutical manufacturing, soil & bio-geochemistry, synthetic biology, metabolomics, healthcare, diagnostic and translational medicine. As a result there is a lot of overlap with measurement science challenges in other industries and my role includes working closely with the other Industry Specialists (FMCG, Aerospace, Defence/Security, Water & Environmental, Pharmaceutical) at Anatune and with our suppliers' R&D/Product managers.

Geoffrey Knott; University of Surrey CP

Dr Geoffrey Knott is a Research Fellow at University of Surrey specialising in spacecraft structures and mechanisms, having previously achieved PhD Mechanical Engineering (Surrey, 2018), MSc Space Science & Engineering (UCL, 2014), and BSc Astrophysics (Aberystwyth, 2013).

Geoff is driven by entrepreneurship and research commercialisation, is member of the Institute of Directors, and has attended numerous enterprise skills development programmes during his time at Surrey including SETsquared, SEPnet, and Student Enterprise Surrey.

Geoff is Director & Co-Founder of HOP — a nutrition business that achieved startup funding from Surrey — whose mission is to give individuals more control over their long-term health and wellbeing through the foods they eat. At present, HOP provides edible insect foods for sports nutrition (HOP BAR) and home cooking (cricket flour).

Rupert Mellor; WP Thompson CP

Rupert Mellor graduated from Royal Holloway University of London with an MSci in Physics in 2014 which included a placement through SEPnet at Sussex and a placement at the National Physical Laboratory (NPL). He then obtained a PhD at Royal Holloway as a joint RHUL/NPL student working on ‘Nanoelectromechanical systems at ultra-low temperatures’. Through attending GRADnet training events Rupert decided to pursue a career in intellectual property and successfully secured a position at WP Thompson as a Trainee Patent Attorney in May last year.

Hibaaq Mohamud; National Physical Laboratory CP

Hibaaq joined NPL’s Nuclear Metrology group in 2015 to complete a PhD in collaboration with the University of Surrey, which focused on the development of functionalised nanomaterials for application in nuclear waste treatment. She has since joined the group as a Higher Research Scientist where she supports the radiochemistry team on the development of rapid radioanalytical procedures for use in both nuclear decommissioning and nuclear medicine.

Doug Offin; National Nuclear Laboratory CP

Doug joined NNL in 2014 and is a Technical Lead in the Instrumentation and In-situ Analysis (IIA) team at the Central Laboratory. The team primarily develops instrumentation and analytical techniques for measurement applications in nuclear environments. This includes visual inspection, thermal imaging, non-destructive testing techniques, automated radiochemical separation, radiometric measurements and wireless communications. The team also carries out experimental work to validate modelling and support safety cases for packages designed to transport and store nuclear material.

Doug also has several years’ experience of R&D in the gas sensing industry including the development and validation of optical and electrochemical sensors for in-situ monitoring of toxic gases. He is familiar with research in the academic arena and was instrumental in the transfer of the StarStream® ultrasonic decontamination technology from lab-based research to commercial development during time spent at the University of Southampton. This work was recognised with a Dean’s Award for Enterprise and the technology was awarded with the IChemE prize for Innovation in Water Management and the S-Lab Product of the Year.

Doug has a Masters of Chemistry degree and a PhD in the use of electrochemical sensors for the study of acoustic cavitation.

Phil Raymond; Department for Business, Energy and Industrial Strategy CP

Phil is a Senior Climate Science Advisor at the Department for Business, Energy and Industrial Strategy (BEIS). While completing his PhD, which focussed on chemical biology research into the treatment of chronic pain, he began working in science policy during an internship at the House of Commons Science and Technology Select Committee, where he worked on inquiries into public communication of science, and the Government’s Forensic Science Strategy. After finishing his PhD, he began working in BEIS as a Policy Advisor in their International Climate Strategy team, before taking up his current role in the Climate Science Team. He is responsible for promoting understanding of climate science issues across Government, and represents the UK at international climate science meetings, including as part of the UK delegation to the Intergovernmental Panel on Climate Change, and the United Nations Framework Convention on Climate Change.

Greg Rigas; M-Solv CP, EP

Dr. Grigorios (Greg) Rigas is currently leading the Advanced Manufacturing group at M-Solv Ltd, which focuses on the development of novel processing techniques for large area printed electronics (PE). After graduating in the top 1% of his class as an Electronic Engineer in Greece, Greg moved to Surrey to pursue an MSc in Nanotechnology and Nanoelectronics, where he received a distinction for his work on PE. In 2013 he was awarded a 4-year scholarship from the National Physical Laboratory (NPL) to pursue a PhD at the University of Surrey (UoS). His research project, titled “Advanced processing and characterisation of printable single crystal electronics”, aimed to tackle the key challenges associated with introducing PE into large-scale manufacture. Under the supervision of Dr. Fernando Castro (NPL) and Dr. Maxim Shkunov (UoS), he (co)-authored more than 10 peer-reviewed journals (including Nature Comms., ACS Nano and IEEE), a book chapter and, presented in more than 20 conferences. Greg is the recipient of a series of academic awards including the 2017 Postgraduate Award for an Outstanding Researcher from the Institution of Engineering and Technology (IET). His current research interests are within the field of printable biomedical devices and energy harvesting- storage configurations.

Emma Ryan; Reaction Engines CP, EP

Dr Emma Ryan currently works at a development engineer, industrialising the manufacturing process for the synergic air- breathing reaction engine (SABRE), at Reaction Engines Ltd. She is also currently a technical author for the BSI and ASTM on a specification for 'Wire for Directed Energy Deposition (DED) Processes in Additive Manufacturing'. She recently completed a doctorate at the University of Surrey and worked as a research engineer at Lockheed Martin, improving the reproducibility of wire and arc additive manufacturing.

Emma previously studied a BSc (Hons) in Physics at the University of Edinburgh and had a summer internship at the Astronomy Technology Centre based at the Royal Observatory. In her spare time, Emma enjoys performing stand-up comedy, making cake and visiting beautiful places.

David Stanley; Henry Royce Institute CP

David has a BSc in chemistry from UCL, and MSc and DPhil (1980) from the University of Sussex. After post-docs at the Universities of Chicago and Sussex he moved to industry, joining the Advanced Materials Group of ICI plc as part of a multi-disciplinary team working on the synthesis and processing of advanced ceramics. He later moved to the Process Technology Group of the bulk chemicals business of ICI, leading small teams on a variety of projects, including assessing process applications for supercritical fluids and the crystallisation of bulk organics.

In 2000, David returned to the academic world in a business development role at Keele University, before joining The University of Manchester in 2003, making the move into the skills development field as Training and Skills Manager for the Northern Aerospace Technology Exploitation Centre (NATEC). In 2005 he became Manager of the EPSRC Engineering Doctorate (EngD) Centre in Manufacturing, and subsequently the EngD Centre in Nuclear Engineering, both based at The University of Manchester.

In 2018 David took up his current role of CDT Development Manager at the Henry Royce Institute, the UK’s national institute for advanced materials, where he is responsible for delivery of the Royce’s training and skills programmes. David’s role seeks to establish a national cohort of advanced materials PhD students and to support an “engaged learning community” of the UK’s materials talent, from both academia and industry, by facilitating access to world-class Royce equipment and training opportunities, sharing best practice and expertise and running special events such as conferences, lectures, workshops, and on-line forums.

David is a Chartered Chemist and Fellow of the Royal Society of Chemistry.

Guilia Thompson; Elekta CP, EP

Giulia Thompson began her Physics studies in Italy at the University Bologna, her home town. She moved to the UK in 1996 with an EU Marie Curie Fellowship and later received her PhD in Radiation Physics from University College London. She joined Elekta in 2000 as an Advance Development physicist, progressing over the years to Senior Research Physicist and Physics Team Leader. She is currently Head of Physics and Research within the UK Global Engineering department of Elekta. During almost 20 years in the radiation oncology industry, Giulia has been involved in a variety of research and development activities bringing innovative products into clinical use; whilst she currently focusses on leading and developing the capability of her functional department, Giulia still much enjoys the technical aspects of her work. She is a named author on over 20 scientific publications and inventor on 3 patents.

Kruna Vukmirovic; The Institution of Engineering and Techonology EP

Kruna is Publisher for the IET Journals portfolio and is responsible for the strategic development and new business direction including partnerships and new journal launches. With over 15 years in STEM publishing, Kruna has previously held publishing roles in a medical communications agency, the Institution of Mechanical Engineers and Sage.

Abstracts

Oral Presentations

Developing Characterisation Measurements for Quantum Key Distribution S. Albosh1,2, T.P. Spiller1 and C.J. Chunnilall2 1University of York, York, YO10 5DD, UK 2National Physical Laboratory, Hampton Road, Teddington, Middlesex, TW11 0LW, UK

Quantum key distribution (QKD) is a method of securely sharing encryption keys between two separated parties, such that the secrecy of the key can be proven without making any assumptions about the capabilities of an eavesdropper.

The security of a key generated via a QKD protocol is confirmed by a theoretical security proof, where this proof relies on the laws of physics and a model of the system being used. However, side channels (deviations between the system model and the real physical system) can be exploited by an eavesdropper to gain information about the key. This compromises the key’s security, which then risks the secrecy of any information encrypted by that key.

To avoid this, the devices used in QKD protocols must be characterised. This allows an accurate and comprehensive system model to be constructed for the security proof and enables the implementation of appropriate countermeasures to protect any side channels.

My work investigates the characterisation of the hardware used in QKD protocols, particularly focussing on phase manipulating devices.

Seeing sustainability from space: Using Earth observation data to populate Sustainable Development Goal indicators Ana Andries1, Stephen Morse1, Richard Murphy1, Jim Lynch1, Emma Woolliams2 1University of Surrey, Dept of Physics, University of Surrey, GU2 7XH 2National Physical Laboratory, Teddington, TW11 0LW

In 2015, member countries of the United Nations adopted the 17 Sustainable Development Goals at the Sustainable Development Summit in New York. These global goals have 169 targets and 232 indicators based on the three pillars of sustainable development: economic, social, and environmental. However, substantial challenges remain in obtaining sufficient data of the required quality and quantity to populate these indicators efficiently. One promising and innovative way of addressing this issue is to use Earth observation (EO). The research reported here updates our original work to develop a Maturity Matrix Framework (MMF) for assessing the suitability of EO derived data for populating the SDG indicators, with a special focus on those indicators covering the more social and economic dimensions of sustainable development. The advanced MMF 2.0 framework set out in this paper is based on a wide consultation with EO and indicator experts (semi-structured interviews with 38 respondents). The paper provides detail of the evolved structure of MMF 2.0 and illustrates its use for one of the SDG indicators (Indicator 11.1.1). The revised MMF is then applied to published work covering the full suite of SDG indicators and demonstrates that EO can make an important contribution to providing data relevant to a substantial number of the SDG indicators.

Keywords: Sustainable Development Goals, Indicators, Earth Observation, maturity matrix

The Myriad Applications of Microresonators M. T. M. Woodley1,2, L. Del Bino1,2, G. Ghalanos1,3, L. Hill4, N. Moroney1,3, J. M. Silver1, A. Ø. Svela1,3, S. Zhang1, G.-L. Oppo4, and P. Del’Haye1. 1National Physical Laboratory, Hampton Road, Teddington, TW11 0LW, UK. 2Heriot-Watt University, Edinburgh, EH14 4AS, UK. 3Imperial College London, Kensington, London, SW7 2AZ, UK. 4University of Strathclyde, Glasgow, G4 0NG, UK.

Microresonators are small structures (sometimes smaller than the diameter of a human hair) that allow us to concentrate a huge amount of light into a tiny volume. Under these conditions, two beams of light travelling in opposite directions can behave very strangely: they pick one preferred direction of propagation over the other -- a process known as spontaneous symmetry breaking. This is not only of fundamental interest, but also forms the basis of a plethora of all-optical devices, including nonreciprocal components for optical circuitry, enhanced sensors for guidance systems and biomolecule detection, oscillators, and cryptographic devices. The tiny form factor of a microresonator, in tandem with our ability to fabricate them directly on a silicon wafer, makes it an ideal candidate for on-chip integration. Since it is possible to construct these devices using existing silicon infrastructure, the required investment for future development will be relatively small.

In this talk, I will outline the fundamentals of microresonators, including how we fabricate them. I will then go over how they can be used to realise some of the above applications – specifically sensors and oscillators – and why these devices will be useful.

Accelerated ageing of polymer composites and the effect of moisture absorption on mechanical and chemical properties J. E. Bone1,2,3, G. D. Sims1, A. S. Maxwell1, S. Frenz2, S. L. Ogin3, C. Foreman3 and R. A. Dorey3 1National Physical Laboratory, Teddington, UK 2Element Materials Technology, Hitchin, UK, 3 Mechanical Engineering Sciences, University of Surrey, Guildford, UK

Background

There has been extensive development of the use of polymer composite materials in the offshore and marine industries, such as in shipping, bridges, piers, and wind or tidal turbine blades. While these materials offer many advantages over traditionally used materials such as steel and timber, knowledge allowing quantification of the durability is still a significant requirement in these aggressive environments. Numerous test methods exist for the accelerated ageing of polymers and polymer composites at the laboratory scale [1], but these to not extend to assessment of in-service performance or establish the remaining lifetime of in-service aged material and structures. It is essential to understand the long-term behaviour of polymer composites with respect to exposure to the environment to ensure accurate design, adequate safety and economic viability.

Current work

This work investigates the use of elevated temperatures to accelerate the ageing of polymer composite specimens when exposed to immersion in water, pressure and mechanical loading. A procedure has been developed using both water baths and autoclaves to simulate and monitor the degradation of polymer composites in a marine environment, with techniques including four point bend flexure, nanoindentation, FTIR, DMA and NMR.

Testing of (unloaded) aged specimens has shown that the increase in moisture content over time causes changes in material behaviour with a decrease in the glass transition temperature, together with changes in flexural strength, flexural modulus, and failure mechanism. Results will be presented on the effect of an applied load during ageing, which significantly affects the diffusion of moisture into the specimens.

Reference

[1] W. R. Broughton and A. S. Maxwell, “Accelerated Environmental Ageing of Polymeric Materials”, NPL Measurement Good Practice Guide No 103, 2007

Using Isotopic Signature of Methane in Budget Estimation E. Chung1,2 A. Drinkwater1,2, T. Arnold1,2, T. Gardiner2, P. Palmer1, C. Rennick2 1School of GeoSciences, University of Edinburgh, Edinburgh, EH9 3FF 2National Physical Laboratory, Teddington, TW11 0LW

Methane (CH4) is the second most abundant anthropogenic greenhouse gas with 100-yr Global Warming Potential of 28, which means it is 28 times more powerful than CO2 on gram to gram basis. As such, precise quantification of the CH4 budget is required in order to quantify and minimise our impact on climate. However, competing hypotheses on the budget to explain the current trends in atmospheric CH4 exist.

Clumped isotopologues of CH4, where multiple isotopic replacements occur within the chemical structure, show potential as an atmospheric tracer which can provide additional constraints on budget estimation, despite their low concentration. Different modelling frameworks can be used to understand how these can aid us in estimating CH4 budget: low-resolution 2D model for outlook upon global CH4 cycle; and high-resolution 3D model with added information on geographical variations in source and sink strengths. Ultimately, the modelling leads into a metrology challenge with the National Physical Laboratory, considering how to measure clumped CH4 in ambient air samples. We demonstrate our works on modelling different isotopologues of CH4, and the outlooks on the importance of metrology in atmospheric composition studies.

Modelling Energy Demand Response Using Long-Short Term Memory Neural Networks J. J. Mesa-Jiménez1,2,3, L. Stokes3, C. Moss3, Q. Yang1, and V. N. Livina2 1Brunel University, Kingston Lane, London, Uxbridge UB8 3PH 2National Physical Laboratory, Hampton Road, Teddington TW11 0LW 3Mitie, The Shard, Level 12, 32 London Bridge Street, SE1 9SG

We propose a method for detecting and forecasting events of high energy demand, which are managed at national level in Demand Side Response programmes, such as the UK Triads. The methodology consists of two stages: load forecasting with Long-Short-Term-Memory neural network and dynamic filtering of the potential highest electricity demand peaks by using the exponential moving average. The methodology is validated on real data of a UK building management system case study. We demonstrate successful forecasts of Triad events with RRMSE ≈ 2.2% and MAPE ≈ 1.6% and general applicability of the methodology for Demand Side Response programme management, with reduction of energy consumption and indirect carbon emissions.

Mobile Air Quality Sampling in London, UK. Geoff Ma1,2 1Department of Chemistry, University of Cambridge, 2National Physical Laboratory, Teddington, TW11 0LW

Professionally driven vehicles, fitted with high quality air quality samplers, are collecting data about London’s air quality as part of the Breathe London project. One aim of the project is to deepen our understanding into the air quality of the streets between the (relatively) sparse reference stations. The information content of these stations is therefore limited to fixed locations – even when used as networks. Mobile data observations provide an increased spatial resolution, providing a new level of information.

Our vehicles sample NO2, NO, O3, CO2 and a variety of particulate measurements (including black carbon); alongside CO2 which can be used as a tracer gas. We will present results from the analyses of the ratio of pollutants to CO2 - providing a method for source apportionment at hyperlocal scales (e.g. fleet mix). The ratios (relative to the tracer) are necessary to mitigate against meteorological effects; bound to be inherent to the dataset.

Visualizing data of this sort is also important. We explore techniques (such as mapping) in order to disseminate a large dataset into understandable and presentable formats.

Geopolymer-Based Stabilisers as an Alternative to Traditional Stabilisers for flexible Pavement Construction Hadi A. Abba1, S. Bhattacharya1, Liang Cui1 1University of Surrey, Dept of Civil and Environmental Engineering, University of Surrey, GU2 7XH

Rigid pavement is more durable than flexible pavement but for the sub-Saharan developing countries the latter is widely used because its initial cost is less and temperature variations have less effect if designed based on Superpave performance graded (PG) binder system. Traditional and by-product stabilisers (cement, cement kiln dust, Bagasse ash, rice husk ash etc.) are widely used by geotechnical engineers in stabilising highly expansive Black Cotton Soil (BCS) for flexible pavement construction in Nigeria because of their robustness and the well-understood chemistry of the stabilisation process. However, their productions (Traditional and by-products stabilisers) release significant quantities of CO2 which is recognised as both a greenhouse gas and threat to the ozone layer. In addition, taxes on energy and CO2 emission are high on these stabilisers. However, metakaolin (MK) non-traditional geopolymer material, a low energy consumption, minimum CO2 emission, readily available and under used resource in Nigeria, could offer alternative to these traditional and by-product stabilisers. Although geopolymers are developed and applied in materials such as: fire resistance materials, concrete, decorative stone artefacts, thermal insulation, low energy ceramic tiles, high-tech composites aircraft interior and automobile, etc., geopolymer-based stabilisers for the construction of flexible pavement have not been widely investigated. Therefore BCS stabilised with 0-15% MK by dry weight of soil treated BCS as subbase material for flexible pavement has been investigated. Although the treated BCS showed improved geotechnical properties, the treated soil was not suitable for use as subbase material for flexible pavement. However, further investigation need to be carried out using alkali-activated MK geopolymer material for treating the BCS as subbase for flexible pavement.

Keywords: Black cotton soil, geopolymer, metakaolin, rigid pavement, stabilisation

Laser Desorptio – Rapid Evaporative Ionisation Mass Spectrometry Platform for Tissue Imaging Daniel Simon (1)(2), Julia Abda (1), Hanifa J.A. Koguna (1)(2), Josephine Bunch (1)(2), Zoltan Takats (1) (1) Imperial College London, London, United Kingdom (2) National Physical Laboratory, London, United Kingdom

Mass Spectrometry Imaging (MSI) is an emerging technique in the field of biochemistry, which enables the capturing of two-dimensional molecular information and histological characterisation of tissues. Several techniques are currently available, e.g. Matrix Assisted Laser Desorption Ionisation, Secondary Ion Mass Spectrometry or Desorption Electrospray Ionisation, however all these techniques have technical challenges. In this presentation a new technique, Laser Desorption – Rapid Evaporative Ionisation Mass Spectrometry (LD-REIMS) is described as an MSI technique suitable for analysing samples under ambient conditions without sample preparation.

A Xevo G2-S QToF MS equipped with REIMS source and coupled with a custom-built sampling platform was used for imaging experiments. Intelliguide CO2 laser (10600nm) and Opolette HE2731 OPO laser (2700- 3100nm) were used to map the Infrared laser parameters. 10µm fresh and formalin-fixed, paraffin-embedded (FFPE) pork liver and cancerous human tissues (obtained under ethical approval) were used as samples.

Initial experiment shows the molecular coverage between 50-1500m/z of the LD-REIMS is sufficiently large for proper analysis. A wide array of metabolites, small molecules, peptides and structure molecules (glycerophospholipids) were observed during initial experiments. The optimal desorption wavelength was ≈2950nm, correlated with the absorption maximum of the water content of tissues. Pulse widths between msec-nsec range were tested, finding the shorter pulses at same fluence to be better for mobilisation. The currently achievable imaging resolution of our system is 70µm. The pulse width and resolution are under further optimisation.

Successful tissue imaging experiments were conducted on several different tissue types. The molecular changes observed in the data correlates with the histopathological status of different tissues. FFPE tissue slides were successfully measured without any sample preparation or washing steps. Combining this feature with the high automation ability of the LD-REIMS could enable autonomous processing of FFPE tissue banks, gaining insight in the molecular changes behind cancer and other diseases.

Validation of Texture Analysis in CT Imaging Christopher Green1,2, Mohmmad Hussein2, Catharine Clark2,3, James Scuffham3 and Phil Evans1,2 1University of Surrey, Stag Hill, Guildford, Surrey, GU2 7XH 2National Physical Laboratory, Hampton Road, Teddington, TW11 0LW 3Royal Surrey County Hospital, Guildford, Surrey, GU2 7XX

Texture analysis (TA) is an emerging field of medical image analysis, which mines information from images, that cannot be obtained with the naked eye. TA has been shown to be a good disease discriminator, survival predictor and useful in treatment planning. However, due to different imaging protocols being used at clinics it is difficult to get a consistent measure of texture across these centres.

Computed tomography (CT) TA phantoms have been used for repeated imaging across multiple parameters, but these phantoms are often only imaged on one or two CT machines, so they cannot assess how TA varies across a range of machines and protocols. Another drawback of current TA phantoms is that they do not have structures specifically designed to assess TA, often having a simple shape and made of a solid material. This means that the texture is coming from the material itself, rather than the structures made from the material.

This research aims to create a novel phantom specifically designed for TA. One potential method for producing a phantom is 3D printing, meaning the phantom can be designed to have a complex, known structure. Knowing the structure allows for a true texture to be calculated and CT simulations to be run and compared to experimental results.

Different approaches for making a phantom have been investigated, these include; infrared radiation assisted evaporative lithography, electrospinning and evaporative lithography using a water-polymer blend with calcium carbonate particles.

Work has also been done to investigate the impact that image reconstruction methods have on texture. The Shepp- Logan phantom has been reconstructed with filtered back-projection using a range of different filters. Texture features were then calculated for each filter method. A variation of over 20 % was observed in some features, indicating that reconstruction filter can have a significant impact on image texture.

Raman Metrology for Live Cell Imaging C. Thomson1,2 Prof D. Graham1, Dr D. Tskritsis2, Dr K. Paton2, Dr N. Belsey2 1University of Strathclyde, Dept of Pure and Applied Chemistry, Glasgow, G1 1XQ 2National Physical Laboratory, Teddington, TW11 0LW

Raman spectroscopy is becoming increasingly utilised to study biological samples, in particular for live cell imaging, due to the minimally-destructive, label free nature of the technique. However, as with any technique using a high- powered light illumination source such as a laser, there is a risk of photodamage to the sample, this is particularly a concern for light and temperature sensitive samples such as live cells. In order to uphold data integrity, it is of paramount importance to ensure chemical changes are due to the process under study, and not simply an artefact of sample damage.

Identifying and preventing photodamage in live cells during analysis is challenging, since there is no standard procedure outlining damage thresholds for live cells under different laser wavelengths, laser powers and exposure times. There are many examples in the literature, but they pertain to a variety of different mammalian cell types/tissues and utilise different techniques, so there is no consistent approach. In addition, these methods often use fluorescent markers to identify damage, which can be inconsistent, and alter the chemistry of the sample.

Within this project we will systematically establish how much laser irradiation a live cell can withstand before damage occurs during Raman spectroscopy by parallel assessment with biological viability techniques; utilising MG-63 osteosarcoma mammalian cells in the first instance. This will enable the design of robust standard operating procedures for Raman analysis that avoid photodamage of live cells, delivering confidence in future Raman analysis through reduced artefacts. This work requires detailed characterisation of the confocal Raman instrument, such as measurements of the magnitude and consistency of laser power incident on the sample and laser irradiation area.

Implantable ultra-flexible bioelectronic mesh: Reinvention of the cardiac pacemaker Cox-Pridmore, D. M.1,2 1University of Surrey, Dept of Electrical and Electronic Engineering, Surrey, GU2 7XH 2National Physical Laboratory, Teddington, TW11 0LW

Disturbances in the heart’s electrical activity result in arrhythmias. Currently, cardiac pacemakers can be implanted to encourage the heart to beat healthily via electrical pulses. However, there are various risks with pacemakers including; battery depletion, unreliable therapeutic output, and immune reaction, which can lead to implant rejection and limited performance. Small, flexible, porous bioelectronics may overcome these issues.

Being small and flexible allows the electronics to be taken up by a needle and transplanted effortlessly. Reducing device size means less tissue displacement and blocking of signalling molecules. While flexible devices can bend with the soft tissues, which limits the amount of strain the device has on the tissue, in turn, reducing chronic inflammation. Increased porosity allows the cells to penetrate the device, thereby improving tissue integration.

After seamless integration, sensitive biosensors can detect cell signalling and the electrophysiology of the cardiac tissue. In response, the bioelectronics can electrically stimulate the cardiomyocytes in a manner that is more personalised to the patient, targeting the arrhythmia as efficiently as possible.

This project aims to create flexible, micro-bioelectronics that can detect and act in real-time to cell signalling and electrophysiology of cardiac tissue. This study can then lead to the development of more sophisticated bioelectronics that can monitor and correct any electrical abnormalities within the heart more efficiently than traditional devices.

Posters

01. Numerical methods for efficiently solving fractionally damped wave equations K. Baker1,2, L. Banjai1,2 1The Maxwell Institute for Mathematical Sciences, School of Mathematical Computer Sciences 2Heriot-Watt University, Edinburgh EH14 4AS, UK

We study numerical quadrature methods that aim to improve efficiency (in particular memory efficiency) and reduce computational complexity in solving wave equations with time fractional damping. These equations include nonlocal fractional derivatives to incorporate the effects of acoustic attenuation of the wave, making them appropriate for modelling high intensity focused ultrasound therapy (HIFU). Initially existence and uniqueness results of the given PDE will be discussed, then a wave equation with an additional fractional (lower order) time derivative is discretized. The nonlocal nature of the fractional time-derivative is treated with convolution quadrature. Recent improvements in storage requirement for convolution quadrature are employed.

02. Modelling and simulations of energy storage devices Joshua Bates1, Dr Constantina Lekakou1, Dr Qiong Cai1, Professor Robert Slade1, Dr Gareth Hinds2 1University of Surrey, Faculty of Engineering and Physical Sciences, University of Surrey, GU2 7XH 2National Physical Laboratory, Teddington, TW11 0LW

In electrochemistry, numerical models are used to predict the activity of energy storage devices such as batteries and supercapacitors. Novel battery technologies, such as lithium-air or lithium-sulphur batteries, benefit from simulation studies in optimising their materials, and more specifically in this study, their porous cathodes. With a theoretical −1 energy density of 11.7 푘푊ℎ 푘𝑔푙𝑖푡ℎ𝑖푢푚, lithium-air batteries approach the energy density of internal combustion engine −1 vehicles (13 푘푊 ℎ 푘𝑔푙𝑖푡ℎ𝑖푢푚) (Lu, et al., 2014). An individual cell structure comprises typically: a lithium-based compound as one electrode (anode), a glass fibre separator with a lithium-salt electrolyte solution, and a porous cathode electrode. Porous carbon is typically used as the electrode in different supercapacitor configurations, as the cathode in Li-air batteries and as the cathode host in Li-S batteries. Its pore size distribution promotes a high power density whereas its pore surface area promotes high capacitance and energy density.

In this project, a one-dimensional transient continuum mass transport model has been developed, including ion transport through multiple pore sizes, and implemented in MATLAB in order to simulate the electrochemical processes in batteries and supercapacitors. Previous models in the literature simulate the porous electrodes with a single uniform pore size. In this project a novel model has been devised, incorporating multiple pore sizes of the electrode material, determined from a pore size distribution. The model was validated against experimental data from the literature and an experimental study in this project. The simulations showed good agreement with experimental data for multiple supercapacitor and battery configurations, demonstrating that accurate simulations can be achieved through a universal model of electrode material.

References Lu, J., Li, L., Park, Jb., Sun, Yk., Wu, F., Amine, K.. Aprotic and aqueous Li-O2 batteries. Chemical Reviews, 2014, 5611-5640.

03. A transfer and scattering matrix model of the NPL plane mirror differential interferometer A. Bridges1,2, A. Yacoot1, T. Kissinger2, R. P. Tatam2 1National Physical Laboratory (NPL), Teddington, TW11 0LW 2Centre for Engineering Photonics, Cranfield University, Cranfield, MK43 0AL

Optical interferometers suffer from non-linearities introduced by unwanted multiple reflections within the optics. Any series of unwanted back reflections that includes a reflection from the target mirror or retroreflector will introduce non- linearities that are periodic with harmonics of the operating wavelength. Existing modelling methodologies commonly applied to the design of displacement measuring optical interferometers fail to account for these multiple reflections. A transfer and scattering matrix approach that accounts for all multiple reflections implicitly has been developed and applied here to the NPL Plane Mirror Differential Optical Interferometer as a demonstration of the applicability of the technique to interferometer design.

The underlying physics of this modelling approach follows that of the FINESSE software, with a series of transfer and scattering matrices used to describe individual optical components. Components are joined at nodes to form an optical network, and a single network matrix is derived that links counter propagating electric field components at each node. In contrast to the FINESSE software, this implementation can inherently model polarising optics, permitting the effects of polarisation mixing, for example due to misaligned waveplates, to be modelled. This implementation can also model the phase change upon reflection or transmission from absorbing materials, such as the metallic films used in NPL interferometers.

The NPL Plane Mirror Differential Optical Interferometer has been chosen to demonstrate the utility of this modelling approach for interferometer design as this interferometer has several parallel surfaces that could produce unwanted multiple reflections, and as it is weakly sensitive to unwanted polarisation mixing if the performance of the polarising components is imperfect. In order to demonstrate the particular benefits of this modelling approach, the effect of the alignments between the parallel surfaces of the polarising beamsplitter, quarter wave plate and corner cube with respect to the measurement and reference mirrors have been investigated.

04. Fast-neutron induced fission studies for Nuclear Data measurements R. Canavan1,2 1University of Surrey, Dept of Physics, University of Surrey, GU2 7XH 2National Physical Laboratory, Teddington, TW11 0LW

Prompt and delayed gamma rays produced by fission fragments during the 238U(n,f) and 232Th(n,f) reactions were studied. A directional beam of fast neutrons, above the fission threshold, was produced by the LICORNE neutron source, using a pulsed 7Li beam from the IPN Orsay tandem accelerator. The gamma rays produced were detected using a new hybrid gamma-ray spectrometer, NuBall, comprising Compton-shielded HPGe detectors and LaBr3 scintillators. This combination of detectors enables high resolution and high efficiency gamma-ray spectroscopy, and ns/sub-ns lifetime measurements, to be performed. Preliminary results will be presented for lifetime measurements and fission fragment identification and separation. An emphasis will be made on the usefulness of the dataset for fast-breeder nuclear reactor studies. The environmental benefits of using fast breeder reactors as a more fuel efficient energy source, and for the destruction of the most dangerous and long-lived nuclear waste, will be discussed.

05. Is urban air quality improving? Understanding trends in combustion particles. K. Ciupek1,2, P. Quincey1,2, G.W. Fuller2, D. Green2 and D. Butterfield1 1National Physical Laboratory, Teddington, TW11 0LW 2King’s College London, Environmental Research Group, London, SE1 9NH

Black carbon (BC) is one of the most influential anthropogenic agents of climate change and negative health effects. Its source in the atmosphere is generally combustion emissions such as vehicle exhausts (especially unfiltered diesel type), domestic and industrial fuel burning, as well as forest fires. The measurement of BC is based on light- absorption by atmospheric aerosol particles. To measure of soot-like carbonaceous material, a thermo-optical (chemical) technique is used and the parameter is called Elemental Carbon (EC). EC, however, essentially splits the total carbon between organic carbon (OC) and EC, and this strongly depends on the method chosen.

Black Carbon was measured by multiwavelength aethalometer AE22 (filter-based attenuation measurement) and the analysis of EC/OC was carried out using Sunset Laboratory Inc. thermal/optical carbon analyser with 1.5 cm2 punch taken from quartz filters.

Data for this comparison are the results of the measurements at three of Defra’s Air Quality Network sites i.e.: Chilbolton (CH) for a rural background, and North Kensington (NK) and Marylebone Road (MR) sites both located in London. Concentrations of both BC and EC have fallen dramatically over the last 10 years. The daily-averaged aethalometer concentrations (BC) were plotted against daily Elemental Carbon (EC) measurements and the annual ratios were calculated for each site. Long term measurements at the MR site might indicate a possible downwards trend in the ratio over time, whereas two other sites with lower concentrations are more variable.

In general, the chemically based Elemental Carbon metric and the optically based Black Carbon metric both quantify the “soot” component of airborne particles and ideally should give the same results. Because these two methods are based on entirely independent principles and moreover are not yet traceable or standardised, new “representative” sources should be developed and characterised to improve accuracy in the field of black carbon measurement.

06. Design and Development of an X-ray Interferometer for Length Metrology Declan Cotter1,2, Andrew Yacoot1, Bill O’Neill2, Paul Shore1 1National Physical Laboratory, Teddington, TW11 0LW 2Institute for Manufacturing, University of Cambridge

For length measurements to be traceable, they must be linked back to the definition of the metre. The 2019 revision of the International System of Units (SI) included an updated version of the Mise en Pratique for the metre, the working document for the practical realisation of the metre. Included within the revision is a new route to traceability for nanoscale length measurements using the lattice parameter of silicon. The d(220) spacing between lattice planes of silicon has been traceably measured and is recognised as a secondary standard of length. One route for the realisation of this traceability route is using an x-ray interferometer (XRI), which can be regarded as a translation stage or ruler where the graduations are based on the lattice spacing of crystallographic planes from which x-rays have been diffracted; in this case the (220) planes with a spacing of 192 pm.

The scope of this project is to produce an XRI for dimensional nanometrology applications, overcoming the current limitations of such devices by utilising advancements in silicon processing; machining and etching. Aspects of the development will involve ultra-precision machining and etching to produce the flexure stage and lamellae. The current focus has been on designing high precision silicon flexure stages capable of sub-nanometre rectilinear actuation over a range of several micrometres, with sub-arc second angular errors. The construction will be monolithic and produced using a combination of conventional machining and laser processing.

07. Fibre-Optic pH Sensor Based on Silver Nanoparticles for Harsh Environments Shaon Debnath1, Sudipta Roy1, Todd Green1 1Department of Chemical and Process Engineering, University of Strathclyde, Glasgow, G1 1XJ

The aim of the fabrication and characterization of a surface plasmon resonance (SPR) pH sensor using coatings of silver nanoparticles on optical fibre which can function in harsh environments. The objective is to determine the optimum conditions for the synthesis of silver nanoparticles which are stable and decorate them on an optical fibre to form a pH sensor. This will unveil the sensitivity of the pH sensor with regards to the minimum particle size of silver nanoparticle and the effect of the multilayer coating.

SPR has become an increasingly exploited technology for the detection and analysis of chemical and biological compounds. Silver nanostructured films fabricated by sol-gel techniques has been observed to exhibit a strong localized surface plasmon resonance (LSPR) at a wavelength around 400 nm [1-3]. The spectral position of LSPR is sensitive to factors such as pH and the size of the nanoparticles.

Although the synthesis of silver nanoparticles and characterization using various analytical techniques have been widely studied, the sensitivity of coating with respect to the change in pH of the solution is still required to advance the current state of knowledge. In this study, the coating of the silver nanoparticles on fibre optic will be prepared by chemical reduction involving a different concentrations of silver nitrate, reaction time and forming multiple layers by dip coating method. The absorbance and light scattering behaviour of silver nanoparticles will be characterized using UV- visible spectrophotometer and the particle size will be characterised by using SEM. The expected result will be used to determine the size range of the nanoparticles and the stirring time that can provide stable particles which exhibit SPS.

08. Towards All-Optical Computing L. Del Bino1,2, N. Moroney1,3, M. T. M. Woodley1,2, and P. Del’Haye1. 1National Physical Laboratory, Hampton Road, Teddington, TW11 0LW, UK. 2Heriot-Watt University, Edinburgh, EH14 4AS, UK. 3Imperial College London, Kensington, London, SW7 2AZ, UK.

With the increasing demand for fast communication and computing power, the conversion between optical and electrical signals is starting to be a bottleneck in the network. A potential solution is to move from electronic computers to optical computers.

The Kerr nonlinearity can be a key enabler for many digital photonic circuits as it allows access to a bistable regime needed for all-optical memories and switches.

A common technique is to use the Kerr shift to control the resonance frequency of a resonator and use it as a bistable, optically-tunable filter. However, this approach works only in a narrow power and frequency ranges or requires the use of an auxiliary laser.

In our alternative approach, we use the asymmetric bistability between counterpropagating light, resulting from the interplay between self- and cross-phase modulation, to allow light to enter the resonator in just one direction.

Logical HIGH and LOW states can be represented and stored as the direction of circulation of light and controlled by modulating the input power.

We study the switching speed, operating laser frequency and power range, and contrast ratio of such a device. We reach a bitrate of 2 Mbps in our proof-of-principle device over an optical frequency range of 1 GHz and a power range of over 3 fold. We also calculate that integrated photonic circuits could exhibit bitrates of the order of Gbps, paving the way for the realisation of robust and simple all-optical memories, switches and routers that can operate at a single laser frequency with no electrical power.

Finally, we demonstrate how this principle enables the realisation of all-optical universal logic gates that constitute the building block of every computer.

09. Extension of Coupled Mode Equations Describing Parametric Amplification T. Dixon1,2, J. M. Williams1, P. J. Meeson2, and C. D. Shelly1 1National Physical Laboratory, Teddington, TW11 0LW 2Royal Holloway University of London, Egham, Surrey, TW20 0EX

Small signal amplification is of paramount importance in quantum information processing. Amplification of single microwave-photons has been achieved with Josephson Parametric Amplifiers (JPA) although with limited bandwidth. Recently, the Josephson Travelling Wave Parametric Amplifier (JTWPA) based on Josephson junctions embedded in a microwave transmission line, has been used to provide quantum-limited, wide bandwidth amplification. The JTWPA utilises non-linear circuit elements (Josephson junctions) to provide a wave-mixing medium. Typically, parametric amplification is achieved via difference frequency generation whereby two input tones - pump and signal – combine, and an idler is generated at the difference of their frequencies. These systems are described by non-linear differential equations where an analytical solution requires many approximations.

We use a SPICE-like circuit simulator WRspice which includes Josephson junctions allowing simulation of the JTWPA. The results from WRspice have motivated an extension of the usual coupled mode equations (CMEs) used to describe the wave-mixing processes. Focusing on a three wave mixing (3WM) scheme and allowing for pump harmonic creation to third order, as well as sum frequency generation between pump, signal and idler tones, we have generated a larger space of allowed states for our amplifier. The propagation of these tones reduces the signal gain – as seen in JTWPA experiments. We are now using NPL’s “Minerva” high-performance computer to perform large scale circuit simulations in WRspice and we compare these simulations to results from the extended CME theory.

We show quantitatively the suppression of signal amplification due to second harmonic generation of the pump. We introduce further discussion on the detrimental effects of sum frequency generation at tones between pump and its second harmonic which may also lie outside the bandwidth of current experiments. We discuss ways of experimentally overcoming such scenarios and motivate the community to consider these higher order terms in the amplification process.

10. Uncertainty quantification in unsupervised learning D. Fernandes1,2 1University of Bath, Dept of Computer Science, University of Bath, BA2 7AY 2National Physical Laboratory, Teddington, TW11 0LW

Unsupervised learning concerns itself with finding patterns in data without specification of what kind of data it is (e.g. labels). This comes in two main forms: clustering and dimensionality reduction. The second one, on which this work focuses, has seen great advances recently with the help of deep learning. Variational Auto-Encoders (VAEs) and all their variants can find meaningful lower-dimensional representations of data, while also being able to generate new data from the learnt manifold. However, they come with the disadvantages of neural networks, mainly that there are no smoothness guarantees in the learnt spaces and no propagation of uncertainty throughout the model. This work reviews several recently proposed building blocks of neural networks which allegedly overcome these disadvantages and shows that they are still present. It also reviews other methods, involving Gaussian Processes (GPs), that do not have these problems, but come with some of their own, specifically difficulty in dealing with high-dimensional data (e.g. images). Ongoing work that aims to resolve this issue is also presented.

11. Proof of concept investigation for in-vivo verification of microbeam radiotherapy using high resolution pixelated detectors S. Flynn1,2, I. Silvestre Patallo2,3, A. Westhorpe3, I. Jones4, J. Jacobs-Headspith4, I. Sedgwick5, N. Guerrini5, T. Price1,2, P. Allport1, A. Subiel2 1School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom; 2Metrology for Medical Physics, National Physical Laboratory, Teddington, United Kingdom; 3University College London, London, United Kingdom; 4vivaMOS Ltd., Southampton, United Kingdom; 5Science and Technology Facilities Council, Rutherford Appleton Laboratory, Didcot, United Kingdom;

Microbeam radiotherapy (RT), a novel form of spatially fractionated radiotherapy, could offer significant advantages over conventional RT treatments due to enhanced dose sparing effects of normal tissues and, hence, improved therapeutic ratios. However, a significant challenge lies in absolute and relative dose measurements required for beam characterization and quality assurance. Traditional small field measurements for output factors, beam position and size are typically performed with GafChromic films, which require a minimum of 24 hours for the detector to develop before the films can be analysed. Additionally, the full process encompasses relatively large uncertainties of 3%.

A high resolution small animal radiation research platform (SARRP) generating 220 kV X-rays (0.68 mm of Cu half- value layer) with a collimators ranging from 10x10mm² down to Ø0.5mm has been used at University College London to test the newly developed vM1212 detector, formerly LASSENA, by vivaMOS (with 50 μm pixel pitch) for its application to small field and microbeam dosimetry. The vM1212 measurements were compared against EBT3 films. Each frames was obtained in <30ms with 100-200 frames obtained for accurate quantification. Relative output factors (OPF) for the different collimators were obtained.

The average OPF difference (vM1212 OPF/EBT3 OPF) was 2% with the maximum observed difference 3% for the 5x5mm² collimator. The vM1212 detector allows for real time beam position and shape, with higher resolution and less noise than the films (calibration and analysis using FilmQA Pro).

The results of this work demonstrate the suitability of thin pixelated detectors for in-vivo verification of beam position, size, shape and intensity in microbeam radiotherapy.

12. Can SPECT Resolution Be Considered Invariant in Partial Volume Correction? R. Gillen1,2, A. M. Denis-Bacelar2, S. J. McQuaid1, K. Erlandsson1, K. Thielemans1, B. F. Hutton1 1Institute of Nuclear Medicine, University College London, London, UNITED KINGDOM, 2National Physical Laboratory, Teddington, UNITED KINGDOM.

Introduction: Partial volume effects degrade image quality and quantitative accuracy. Most partial volume correction (PVC) methods assume spatially invariant resolution. In SPECT imaging, however, the resolution may change under different imaging conditions. This work aimed to investigate the possible bias introduced by PVC when assuming spatially invariant resolution.

Methods: Digital phantoms, of varying complexity, were generated with 'point sources' at four positions. These were forward projected, then reconstructed using OSEM. Gaussians were fitted to the Point Spread Function (PSF) of each reconstructed point source, giving FWHM values in radial and tangential directions for different phantoms and conditions. A second set of phantoms, of the same shape and attenuation as above, were also generated with hot regions representing tumours. These were convolved with two different kernels; one representing an appropriate PSF for the specific imaging conditions, and one representing a ‘standard’ PSF. The bias introduced by applying PVC with an inappropriate PSF was estimated.

Results: Resolution varied significantly depending on position within an object, and direction of measurement. There were differences of up to 36% between radial and tangential resolution, depending on the object shape and attenuation, and position within the object. Resolution was also affected by the distribution of activity. Applying Resolution Modelling improved the resolution in most cases but introduced artefacts and took longer to converge. Using a standard PSF for PVC introduced a bias which depended on lesion diameter and tumour to background ratio (TBR). For TBR = 11, biases of 8-33% were demonstrated for lesions with diameters between 3cm and 0.9cm.

Conclusion: The assumption of spatial invariance is inappropriate for PVC of SPECT imaging and may lead to inaccurate quantification. Measurement of the PSF, specific to patient and position, is required for accurate PVC, with potential to improve accuracy of tumour dosimetry in patients undergoing molecular radiotherapy.

13. Interlaboratory evaluation of MALDI and DESI MSI in the CRUK Grand Challenge programme Melina Kyriazi1,2, Amy Burton1, Kenneth N. Robinson1, Ala Al-Afeef1, Bin Yan1, Efstathios Elia1Teresa Murta1, Spencer Thomas1, Chelsea Nikula1, Rory Steven1, Alex Dexter1, Adam Taylor1, Richard Goodwin3, Zoltan Takats2, Josephine Bunch1,2 1National Centre of Excellence in Mass Spectrometry Imaging, National Physical Laboratory, Teddington, UK; 2Department of Surgery and Cancer, Imperial College London, London, UK; 3AstraZeneca, Cambridge, UK

MALDI and DESI mass spectrometry imaging (MSI) are techniques which allow chemical mapping of numerous analytes simultaneously and are experiencing an increasing application in cancer research. Interlaboratory studies are important to determine whether these techniques are effective, fit for purpose, and transferable across research centres. Reproducibility across research centres is a major obstacle in moving MSI towards routine use. Within the CRUK Grand Challenge programme, DESI and MALDI MSI have been performed at multiple research centres using a range of instruments to evaluate these qualities.

Serial sections of mouse xenograft tumour samples were analysed by DESI MSI in negative ion mode at Imperial College London (ICL) and the National Physical Laboratory (NPL) using a Waters Xevo G2-XS (ICL) and a Waters Synapt G2-Si (NPL). Data were compared to assess analyte coverage and determine any differences in metabolite detection by instrument and site. The results of this work have confirmed the need for additional studies where key metabolites have been chosen to act as standards to better assess molecular coverage and instrument detection capabilities. Thus far, preliminary analysis of standards printed onto glass slides has been completed for multiple instruments and modalities at NPL. Work is ongoing to prepare more complex models including printing standard-spiked plasma onto glass slides and evaluating the application of standard-spiked homogenates and standard-printed tissues. The limit of detection and sensitivity of measured metabolites is being assessed to provide confidence to the evaluation of biological samples using these techniques. Future work will include a full multi-modal, multi-site comparison to assess repeatability and reproducibility of results to best inform the MSI community in experimental design.

14. Determining the level and location of functional groups on few-layer graphene and their effect on the mechanical properties of nanocomposites Elizabeth J. Legge1,2, Keith R. Paton1, Magdalena Wywijas1, Greg McMahon1, Rory Pemberton1, Naresh Kumar1, Arun Prakash Aranga Raju3, Craig Dawson3, Andrew Strudwick3, James W. Bradley4, Vlad Stolojan2, S. Ravi P. Silva2, Stephen Hodge5, Barry Brennan1, Andrew J. Pollard1 1National Physical Laboratory, Hampton Road, Teddington, Middlesex, UK 2Advanced Technology Institute, University of Surrey, Guildford, UK 3Graphene Engineering Innovation Centre (GEIC), University of Manchester, Manchester, UK 4Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool, UK 5Versarien Plc., Cheltenham, UK

Graphene is a highly desirable material for a variety of applications, such as nanocomposites, and can be functionalized to alter the ultimate product properties, such as tensile strength. However, often the material properties of the functionalized graphene and the location of any chemical species, attached via different functionalization processes, are not known. Here we characterize a commercially-available powder containing few-layer graphene (FLG) flakes before and after plasma or chemical functionalization with either amine or hydroxyl groups. Alongside confocal Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) results, tip-enhanced Raman spectroscopy (TERS), time of flight secondary ion mass spectrometry (ToF-SIMS) and NanoSIMS were used to examine the physical and chemical changes in the FLG material at both the micro- and nanoscale. These are the first reported TERS measurements on commercially- available graphene, which show the location of the defects and variations in the level of functionalization due to different processing. Nanoscale TERS images of the Raman D-peak intensity reveal variations within sub-micron size flakes and changes due to the different functionalization processes and species. Graphene-polyurethane composites were then produced and the dispersion of the graphitic material in the matrix was visualized using ToF-SIMS. Finally, mechanical testing of the composites demonstrates that the final product performance is enhanced but differs depending on the original material properties of the unfunctionalized and functionalized material.

15. Preliminary Field Trial of CHAFF: CubeSat Hyperspectral Application For Farming C. Middleton1, C. Underwood1, C. Bridges1, E. Woolliams2 and N. Fox,2 1Surrey Space Centre, University of Surrey, GU2 7XH 2National Physical Laboratory, Teddington, TW11 0LW

A CubeSat constellation of hyperspectral instruments has the potential to benefit a wide variety of applications, including precision agriculture, climate studies and disaster relief. However, the challenges of providing high spectral/medium spatial resolution from such a small platform are great.

CHAFF (CubeSat Hyperspectral Application For Farming) is a concept prototype of a CubeSat-based hyperspectral imager, with the intention of providing high fidelity hyperspectral data cubes to the agricultural and scientific communities. A holistic design methodology has been employed, considering all of the challenges of its intended platform since inception, such as restricted data downlink rates and pointing stability/accuracy. This has resulted in an instrument design which can employ optically aided geometric co-registration techniques, thus aiding the construction of the data cube on-board the satellite. Furthermore, this facilitates the use of powerful lossless data compression schemes in order to alleviate the data downlink bottleneck. In addition, CHAFF will be calibrated using a tuneable laser source at the National Physical Laboratory, enabling rapid and accurate pre-flight spectral, radiometric and stray light characterisation, thereby allowing the production of CubeSat constellations of hyperspectral instruments.

CHAFF has reached the prototype stage, and a preliminary field trial has been carried out. A promising spectral resolution has been achieved on the bench-top of 3nm at 625nm. The optical component of the geometric co- registration method has been demonstrated with the capture of an auxiliary image, and associated spectral image. The spectrum achieved shows promising results in terms of instrument performance and signal-to-noise ratio. Future work, including instrument calibration and further field trials, will also be discussed.

16. Automatic Detection of Canine Soft Tissue Sarcoma Using Transfer Learning Algorithms A. Morisi1, T. Rai2, N. J. Bacon 4, S. A. Thomas3, R. La Ragione1, M. Bober2, K. Wells2, B. Bacci5 1School of Veterinary Medicine, University of Surrey, Guildford, GU2 7AL, United Kingdom 2Centre for Vision Speech and Signal Processing, University of Surrey, Guildford, GU2 7XH, United Kingdom 3National Physical Laboratory, Teddington TW11 0LW, United Kingdom 4Fitzpatrick Referrals Oncology and Soft Tissue, Guildford, United Kingdom 5Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy

A major challenge in the diagnosis of canine soft tissue sarcoma (STS) is the high inter-reader variability between pathologists. However, deep learning methods are capable of automatically learning representations of such data and so could improve the accuracy of tumour detection. In this study we aimed to evaluate the use of transfer learning to classify grade 1 (lowest grade) canine STS against normal tissue.

Whole-tissue digitized images of histopathology slides (WSI) obtained from an oncology referral hospital were used for training/validation of the deep learning algorithm. The canine STS dataset was created from 10 WSIs that contained STS grade 1 and normal tissue. Sample patches of 256 x 256 pixels suitable were used. Approximately 4000 patches were used for training and 1000 patches for validation. Transfer Learning was applied via fine-tuning of the VGG19 convolutional neural network (CNN) using a publicly available dataset and then bottleneck feature extraction applied to the STS data set.

Pilot results demonstrate improved performance using transfer learning compared to training on the dataset alone, with accuracy increasing from 48.50% to 69.20% and precision, recall and F1-scores all increasing from between 0.40-0.47 to 0.69. Aggregated transfer learning with ‘fine-tuning’ marginally improved performance further.

Transfer learning is a promising technique for digital pathology through improved classification performance. Aggregated Transfer Learning produced marginally better classification metrics compared to models pre-trained using the ImageNet dataset. Further studies will aim to improve the statistical significance of the results, the morphological features assessment and recognition for the grading of canine STS.

17. Development of Cellular Metabolomics Catherine Munteanu1,2,3, Chelsea Nikula1, Shahd Abuhelal2, Richard Goodwin3, Zoltan Takats2, Josephine Bunch1,2 1National Physical Laboratory 2Imperial College London 3AstraZeneca

Mass spectrometry (MS) is a powerful technique which enables the detection of thousands of compounds at one time. Recent advances in MS methods have allowed the analysis of single cells providing a wealth of metabolomic information at the cellular level. Electrospray is one of the more promising MS methods to utilise in these analyses as cells can be analysed in suspension. However, the application of this method to single cell metabolomic studies can be laborious and can suffer from low throughput due to limitations in cell sorting. The following work highlights preliminary investigations into the hybridisation of a flow cytometer and an electrospray mass spectrometer. Currently we are developing these instruments for an offline cell sorting mass spectrometry protocol.

One of the challenges in coupling these instruments has been finding a solvent that suits both cell sorting and MS. An examination of solvent solutions to suit flow cytometry, mass spectrometry and cell viability was carried out and few solvents were proven to be suitable. In tandem, we have been investigating the constructions of the instruments and have tested various capillary materials and diameters to determine which is most compatible with a cell suspension. Here, a homemade electrospray has been designed and constructed using steel capillary tubing with an inner diameter of 150 µm to allow delivery of a cell suspension in a 50% methanol solvent system to the mass analyser.

So far, investigations into the fluidics has allowed us to find suitable solvents that permit offline cell sorting and mass spectrometry. The electrospray is being developed to eventually analyse single cells from a suspension. Currently we have found solutions able to pass cell suspensions through the electrospray with minimal clogging. The method for offline cell sorting and cell metabolomics is within reach giving a promising outlook for a possible online method in the future.

18. Radiotherapy MLC Upstream Leaf Edge Detection Using Lassena Large Area MAPS J. Pritchard1, J. Velthuis1,2,3, L. Beck1, R. Hugtenburg2,1, C. De Sio1 1University of Bristol, School of Physics, Bristol, United Kingdom 2Swansea University, Swansea University Medical School, Swansea, United Kingdom 3University of South China, School of Nuclear Science and Technology, Hengyang, China

Multileaf collimators (MLC) are an integral component in modern radiotherapy as they shape the MV photon treatment field and therefore need to be closely controlled. Currently, MLC leaves are calibrated to ±1 mm every 3 months, however leaves can drift beyond this during calibration dates and treatment verification only occurs post-treatment. Furthermore, cases of stuck leaves have been reported. MAPS are radiation hard in photon and electron irradiation, have high readout speeds and low attenuation which makes them an ideal upstream radiation sensor.

Here, we report results using the Lassena MAPS, which has a low attenuation of < 1%, is12 x 14 cm2in size and is three side buttable. A2 x2 matrix of the Lassena sensors covers the entire treatment area so is clinically deployable. We have previously shown that the Achilles MAPS can reconstruct 1 cm wide leaf edge positions with a precision of 52 ± 4 μm in 0.1 sec of treatment beam. The Achilles however, is 6 x 6 cm2 in size, is not buttable and hence, cannot be used for real time clinical monitoring. Additionally, Achillies has a pixel pitch of 14.5 μm whilst the Lassena has a 50 μm pixel pitch.

Experiments were conducted in which the Lassena sensor was placed in the treatment field of an Elekta Synergy LINAC. An MLC leaf of width 0.5 cm was placed iteratively at different extensions. Sobel-based methods were used to calculate leaf edge positions, resolutions and plot as a function of set leaf position. The correspondence between reconstructed and set leaf position was excellent and resolutions ranged between 52.9 ± 8.5 μm and 142 ± 31.6 μm at the iso centre for 0.3 sec of treatment beam. This is significantly lower than the ± 0.5 mm uncertainty in LINAC set position.

19. Different Deep Learning Loss functions for grading Mast Cell Tumors using a weakly imbalanced histopathological dataset. T. Raia, A. Morisib, S. A. Thomasc, N. J. Bacond, B. Baccie, R. M La Ragioneb, M. Bobera, K. Wellsa aUniversity of Surrey, Centre for Vision, Speech and Signal Processing, Guildford, United Kingdom bUniversity of Surrey, School of Veterinary Medicine, Guildford, United Kingdom cNational Physical Laboratory, Teddington, United Kingdom dFitzpatrick Referrals Oncology, Guildford, United Kingdom eUniversity of Bologna, Department of Veterinary Medical Sciences, Bologna, Italy

Digital pathology datasets are often hard to obtain for research purposes due to the invasive nature of a biopsy. As a consequence, acquired datasets may present issues such as a low number of samples or class imbalance. An imbalanced dataset is impractical for the majority of Deep Learning algorithms. The focal loss was introduced as an alternative loss function for highly imbalanced data, where the largest class is down-weighted, focusing on the minority class, thus reducing majority class bias. Another loss function of interest is the LQ loss, commonly used for noisy labels, which is typical in weakly labeled datasets. We compare each loss function to the standard binary cross entropy, using a highly imbalanced canine Mast Cell Tumors (MCT) dataset, for the task of clinical tumor grading.

20. Scope and limitations of Nuclear Magnetic Resonance techniques for characterisation and quantitation of vitamin D in complex mixtures Cameron Robertsona, Robert A. Lucasb, Adam Le Gresleya* aKingston University, Penryn Road, Kingston Upon Thames, UK. bGlaxoSmithKline Consumer Healthcare, Weybridge, UK.

The accurate determination of vitamin D in skin is of considerable importance in evaluating penetration of skin health products through the different layers of the skin. We report on the characterisation and quantitation of vitamin D in an idealised sample and in complex mixtures which mimic that of a typical skin cream, using qNMR, 2D NMR and DOSY techniques. The characterisation and quantitation conditions were acquired over several heterogeneous samples. This allowed for analysis of how dynamic range and complexity of different sample mixtures affect the Limits of Detection (LOD) and Limits of Quantitation (LOQ) of vitamin D. NMR is of particular value to this task as it is non-destructive, uses a primary ratio method for quantification, and tolerates a wide variety of hydrophilic and hydrophobic components within a given matrix. In this investigation we have attained a trueness level <10%, repeatability values of <1% and brought the limit of quantitation down to 100nM (≈limit of baseline range of vitaminD2 and D3 per litre seen in vivo), commenting on the limitations observed, such as peak overlap and sensitivity limits. Pure shift optimised sequences allow us to reduce peak overlapping, allowing further characterisation of individual compounds and the separation of complex mixtures using NMR.

21. Investigating Biological Response of Combined Radiation and Magnetic Field Exposures with Nanoparticle Contrast Agents Emily Russell1,2, Miriam Barry2, Ben Russell2, Hibaaq Mohamud2, Giuseppe Schettino2, Conor McGarry3, Kevin Prise1 1Centre for Cancer Research and Cell Biology, Queen’s University Belfast, Belfast 2National Physical Laboratory, London 3Northern Ireland Cancer Centre, Belfast City Hospital, Belfast

MR-Linacs allow radiotherapy treatments to be carried out alongside MRI imaging for improved image guidance. Contrast agents are required in MRI to improve tumour visibility. Gadolinium conventional (Dotarem) and nanoparticle (AGuIX) contrast agents as well as Iron-oxide nanoparticles (SPIONs) are investigated as radiosensitisers for their preferential uptake in tumours, and ability to absorb radiation, causing more DNA damage. Investigations were carried out using 4 cancer cell lines; H460 (lung), DU145 (prostate), MiaPaCa2 (pancreas), and U87 (brain).

Clonogenic assays were performed using a 225kVp x-ray source in combination with 0.1mM of SPIONs and 1mM of AGuIX, and a range of concentrations (0-20mM) for Dotarem. Immunofluorescence assays were performed with 6MV x-rays for DU145 cells, in the presence of a 1.5T magnetic field, to determine the number of double strand breaks in the DNA. Uptake measurements were performed for Dotarem and AGuIX using ICP-MS to investigate the quantity of Gadolinium taken up by the cells.

No radiosensitisation was seen with Dotarem or AGuIX at 225kV, however radiosensitisation from SPIONs appears to be cell line specific, with H460 cells showing a Dose Enhancement Factor (DEF) of 1.33 at 8Gy. In combination with a 1.5T magnetic field, at 6MV, a significant increase in DNA damage was seen with DU145s for SPIONs, with the number of foci found as 34.5±3.80 for 1hr post-irradiation. ICP-MS inferred a cell-specific nature of Gadolinium uptake, with MCF7s having the highest Dotarem and AGuIX detected, with 10.5±817fg and 5.26±3.77pg for 0.2mM and 1mM respectively.

This work indicates the potential for SPIONs to be used as radiosensitisers for radiotherapy with MRI. However, clonogenic assays with 225kVp x-rays indicated no radiosensitisation with Dotarem or AGuIX, although a cell-line specific nature of uptake. Ongoing work investigates the uptake of SPIONs within cells through ICP-MS, in order to relate intracellular concentration to biological effects.

22. Power Quality Analysis in 25 kV 50 Hz AC Railway System Networks Y. Seferi1 1Dept. of Electronic and Electrical Engineering, University Strathclyde, Glasgow, G1 1XQ

Power quality (PQ) phenomena superimposed on voltage and current signals of railway electricity networks differ from those present in transmission and distribution electricity grids. Trains are mobile and interact with traction substations (TSs), overhead contact lines (OCLs) and other trains within the same supply section.

Trains continuously exchange power during acceleration, coasting and notably during regenerative braking, giving rise to an energy flow from TS to the train, but which may be in the opposite direction, or directly exchanged between trains. This producer-consumer behaviour of the locomotive with the rest of the system, further deteriorates the PQ of the railway grid.

It is also observed that electric signals of railway networks are characterised by short variations in voltage magnitude and frequent periodic voltage interruptions due to specific characteristics of the network configuration, and specific operating conditions (e.g. pantograph detachment from the OCL).

Presently, there are no standardized procedures focused on PQ measurement techniques explicitly for railway applications. This work evaluates whether the standard PQ measurement algorithms defined in IEC 61000-4-30 and used in monitoring 50 Hz electrical grids are sufficient for an accurate evaluation and classification of PQ parameters present in 25 kV AC railways. A new algorithm has been developed to characterise different types of interruption, distinguishing between causes due to network configuration or by other factors. For voltage dips and swells it is also shown that a smaller window size (less than 1 cycle) produces the most accurate estimate of the magnitude and duration. A joint-time frequency analysis method combined with a sliding window of half-cycle difference is used to evaluate the harmonic content of the signals, providing visibility which is not achieved through EN 61000-4-30 due to aggregation of the results. This work therefore provides new recommendations for PQ measurement algorithms for AC railways.

23. Large Scale Inference and Optimal Sensor Placement with Applications to Environmental Monitoring Louis Sharrock1,2, Nikolas Kantas,1 1Department of Mathematics, Imperial College London, London, SW7 2AZ 2Postgraduate Institute, National Physical Laboratory, Teddington, TW11 0LW

Ambient air pollution poses a significant threat to global health and has been associated with a vast range of adverse health effects. Fine particulate matter (PM2.5) in particular has been established as a key driver of global health issues. In this context, the accurate monitoring of pollutant exposure is of clear relevance.

Modelling complex environmental phenomena such as air pollution requires the use of a large number of sensors that collect data frequently and are distributed over a large region in space. This motivates the use of partially observed space-time varying stochastic dynamical models. These are both temporally dynamic and spatially descriptive; and provide a natural framework by which to account for uncertainty in both the data, and our knowledge of the underlying physical process.

In this research, we consider modelling spatio-temporal environmental phenomena via a physically motivated linear Gaussian state space model. We assume that the process of interest evolves according to a particular stochastic partial differential equation (SPDE); namely, the stochastic advection diffusion equation. This SPDE is determined by several parameters, which can be interpreted as explicitly modelling physical phenomena such as advection and diffusion which occur in many natural processes. We assume that this process is hidden, but generates noisy observations according to a linear observation equation. This equation is also determined by several parameters, which can be interpreted as the varianc(es) and bias(es) of the sensors used to measure the latent process.

We are interested in the problem of simultaneously estimating the parameters, and optimally placing the measurement sensors, in this model. Importantly, the parameter estimation and sensor placement are both to be performed online. We propose a novel solution based on a continuous time stochastic gradient descent scheme, and provide numerical examples illustrating the successful application of this methodology to the stochastic advection diffusion equation.

24. Beam Profile Investigation of an Optoelectronic Continuous-Wave Terahertz Emitter J. F. Smith1,2, S. Nellen3, S. Lauck3, B. Globisch3 and M. Naftaly2 1University of Surrey, Dept of Physics, University of Surrey, GU2 7XH 2National Physical Laboratory, Teddington, TW11 0LW 3Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute, Einsteinufer 31, 10587 Berlin, Germany

In the last decade, the Terahertz (THz) frequency range, particularly the frequencies below 1 THz, have attracted significant interest for wireless communication. Optoelectronic continuous-wave (cw) THz emitters show great potential for these applications due to the compatibility with existing fibre-optical networks and the feasibility of highly integrated devices[1]. PIN photodiodes (PD), a well established type of cw THz emitter currently used in THz spectroscopy, are promising candidates for future communication links at THz carrier frequencies[2]. As the THz beam profile in a communication link could not be formed using lenses and mirrors, the radiation pattern and propagation of THz beams from these emitters into free-space is of major interest and merits investigation.

To this end, the beam profiles of two optoelectronic cw THz emitters have been investigated in the frequency range 50-200 GHz. The radiation pattern for each emitter has been measured by a calibrated pyroelectric power detector. The emitter beam profiles have been obtained by line-scanning the detector at a constant distance from the emitter along axes parallel (E-field) and perpendicular (H-field) to the emitter polarisation. These scans were repeated at different distances from the emitter. These results have been compared with simulations performed with High Frequency Structure Simulator (HFSS).

The results of these investigations showed the spatial power distribution of the lower frequencies to be broader than expected. Considerable differences in features were observed between the beam profiles of the two emitters studied, although overall beam profiles and widths were similar. Notably, all beam profiles had distinct frequency- and polarisation-dependent special features. These results of these studies may be utilised for link budget estimation and designing suitable THz optics. The comparison with the simulations makes it possible to develop a more precise HFSS model of the emitter, aiding the design of future optoelectronic THz emitters.

[1] T. Nagatsuma, et al., “Advances in terahertz communications accelerated by photonics,” Nat. Photonics, vol. 10, no. 6, pp. 371-279, 2016. [2] C. Castro, et al., “32 GBd 16QAM Wireless Transmission in the 300 GHz Band Using a PIN Diode for THz Upconversion,” OFC, 2019.

25. Characterization of Hypoxic Organoid System for Radiation Response Studies of Pancreatic Ductal Adenocarcinoma Gabrielle Wishart1,2, Priyanka Gupta1, Giuseppe Schettino2,3, Andrew Nisbet2,4, Eirini Velliou1 1Bioprocess and Biochemical Engineering Group (BioProChem), Department of Chemical and Process Engineering, University of Surrey, Guildford, GU2 7XH, UK 2Department of Physics, University of Surrey, Guildford, GU2 7XH, UK 3National Physical Laboratory, Teddington, TW11 0LW, UK 4The Royal Surrey County Hospital, Guildford, GU2 7XX, UK

INTRODUCTION

Advances in tissue engineering are emerging to bridge the gap between 2D cell culture models and xenografts, more readily replicating tumour architecture, porosity, cell-cell and cell-matrix interactions, as well as hypoxic expanses [1]. Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with a notoriously complex and hypoxic tumour microenvironment (TME) [2, 3]. PDAC radio-resistance and treatment failure is largely associated with dense hypoxia. Here we plan to replicate PDAC TME in a hypoxic 3D porous polymeric scaffolding system, to aid clinical application and optimisation of radiotherapy.

METHODS

3D polymeric scaffolds are created utilising the Thermally Induced Phase Separation method [4]. The human PDAC cell line PANC-1 is cultured in hypoxic levels of 5%, 1%, 0.5% and 0.1%. Radiotherapy exposures will be performed using an orthovoltage x-ray unit at the Royal Surrey County Hospital giving 2 Gy, 6 Gy and 8 Gy radiation doses. Scanning electron microscopy & Confocal Laser Scanning Microscopy (CLSM) will be employed to characterize the scaffolds Evaluating cellular organisation and viability, the detection of caspase and apoptosis and the distribution HIF-1-alpha, the latter providing indication of the oxidative stress spatial distribution and its relation to treatment resistance.

CONCLUSIONS & FUTURE WORK

This work provides a novel near replica of the hypoxic PDAC TME that provides a platform for studying radiotherapy and hypoxia-associated resistance for clinical application. Future work will investigate chemo-radiotherapy and static magnetic field radiotherapy combinations.

ACKNOWLEDGEMENTS:

This research was supported by the Department of Chemical and Process Engineering of the University of Surrey as well as the National Physical Laboratory.

REFERENCES:

[1] Totti, S., et al. (2018). RSC Advances, 8(37). [2] American Cancer Society. (2019). Cancer Facts and Figures 2019. [3] Xie, D., & Xie, K. (2015). Genes & Diseases, 2(2), 133–143. [4] Totti, S., et al. (2017). Drug Discovery Today, 22(4).

26. Development of Hybrid Quantum Interference Devices for NMR D. R. M. Woods1,2, A. J. Casey2, J. Saunders2, and C. D. Shelly1 1National Physical Laboratory, Teddington, TW11 0LW 2Royal Holloway University of London, Egham, Surrey, TW20 0EX

Hybrid Quantum Interference Devices (HyQUIDs) are superconducting devices exploiting the phenomenon of Andreev reflection occurring at a superconducting-normal metal interface. The HyQUID directly relates the resistance of the device to the magnetic flux in the superconducting loop which means the HyQUID is an extremely sensitive magnetometer. HyQUIDs can be used in a wide variety of sensing applications, ranging from medicine to fundamental research, and is analogous to the SQUID which is ubiquitous in the measurement of magnetic fields. Our work focusses on developing HyQUIDs for use in nuclear magnetic resonance (NMR), providing a new way to measure NMR signals with devices that may have decreased power dissipation and lower intrinsic noise. HyQUIDs have already been implemented by York Instruments for magnetoencephalography (MEG), and initial measurements have been performed on HyQUIDs they have provided [1]. These niobium-based HyQUIDs have been characterised at 4 K, results include investigations of the flux-to-voltage transfer function of the device, and the effects of on-chip flux modulation. As well as commercial devices, we have begun development of our own aluminium-silver HyQUIDs designed to operate at low (sub-1 K) temperatures. The SuperFab clean room facility at Royal Holloway has been used to begin fabricating these HyQUIDs. A bespoke measurement probe for liquid helium testing has been designed and manufactured. The probe features a superconducting solenoid to produce large (~ 50 mT) magnetic fields and helium fill lines for NMR measurements.

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Thank you The Organising Committee would like to thank you for attending the 4th PGI Conference.

The Organising Committee Emma Braysher (Chair) Lewis Hill Ben Webster Minal Patel Edward Chung Patrick Bevington

PGI Team Richard Burguete Debbie Meikle Leah Chapman Joanna Carstens Linden Fradet

We also give special thanks to Vishanti Fox, Amy Pearce and Veronica Benson for their involvement on the second day. Finally, we would like to thank the Events and Catering teams at NPL for their support of this event.

#PGIconference #measuretoimpact

PGImetrology pgimetrology

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