Fluorescence microscopy enables measuring the mechanical properties of liquid interfaces without disturbing them.
The mechanical properties of complex liquid interfaces, i.e. interfacial rheology, are crucial for understanding the stability of emulsions and foams, including everyday examples such as skin cream and whipped cream.
Conventional techniques to measure interfacial rheology rely on macroscopic probes, like a needle or a ring, directly attached to the water-oil interface. However, this couples the interfacial flow to the bulk flows in the water and oil phases, thereby limiting measurement sensitivity. Moreover, the presence of a macroscopic probe in the water-oil interface could significantly affect the structure of the interface itself, which would mean that the mechanical properties of the measured interface are not quite the same as those of the interface without a measurement probe in it.
In their Journal of Rheology paper (and corresponding Scilight showcase), a team of researchers from The University of Edinburgh, Delft University of Technology, and the University of Gothenburg present a contactless method to measure the interfacial rheology of liquid-liquid interfaces using fluorescence microscopy.
One of the authors, Dr Job Thijssen from the School of Physics and Astronomy, explains the method: "Our typical sample is a layer of oil on top of a layer of water, with micron-sized particles attached to the interface between the water and the oil layer. We then rotate the upper (oil) layer in a controlled manner and we measure the response of the particle-laden water-oil interface using a microscope. As we control the rotation of the upper (oil) layer, we can calculate the stress (force per unit area) applied at the interface. From the microscopy videos, we can extract the strain (deformation) of the interface in response to that stress. Hence, we can quantify the mechanical properties of the interface in a flow curve (plot of stress vs shear)."
Importantly, the method should only require relatively common equipment, for example a fixed-rate motor and an optical (fluorescence) microscope, so the team hopes that their paper will contribute to interfacial-rheology measurements becoming more accessible. Through the Edinburgh Complex Fluids Partnership, they are also hoping to apply the novel contactless interfacial rheology technique to everyday and industrial samples.
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Scientists uncover the surprising hydrogen content variability in novel lanthanum hydrides.
Superconductors
It has been a long-standing goal of physicists, chemists and material scientists to find a superconductor which works at room temperature. Such a discovery would transform our societies by allowing us to achieve more work while using less natural resources and creating reduced waste.
There are many applications which currently use materials with superconductors, such as MRI machines, radio and television broadcasting and wireless communications, electric motors and generators. At present, the highest temperature superconductors can only work under extremely high pressures, such as those near the centre of the Earth.
Lanthanum hydrides
Recent research suggests that hydrogen-based solids are among the top contenders for superconductors. Since 2015, high-pressure sciences have been at the leading edge of the synthesis of materials with high superconducting critical temperature (Tc), namely with a breakthrough Tc of 260 K reported in the lanthanum hydride (La-H) system at 1,600,000 times atmospheric pressure. Yet, incongruities in experimental measurements suggested other phases to be formed along with LaH10+δ. These undiscovered lanthanum hydrides, which also anticipated to be very high temperature superconductors, were expected to play an active role in the interpretation of the data to assess superconductivity.
Hydrogen content variability
Dr Dominique Laniel led a team of international collaborators from the University of Bayreuth and Linköping University in employing extreme pressure and temperature conditions to synthesize seven lanthanum hydrides, including five of which were previously unobserved.
A detailed investigation of these hydrides determined that their hydrogen content for a given lanthanum atoms’ arrangement varies depending on pressure and their synthesis conditions—an observation key to understanding pressure-formed hydrogen-based superconductors.
The team synthesized five novel lanthanum hydrides: LaH~4, LaH4+δ, La4H23, LaH6+δ and LaH9+δ, along with the previously known LaH3 and LaH10+δ. To accomplish this, lanthanum and paraffin—i.e. a hydrogen reservoir—were first squeezed to enormous pressures of 0.96 to 1.76 million times the atmospheric pressure in between two tiny diamond anvils and heated to temperatures of more than 2200°C using high power lasers. Then, to characterise the atomic arrangement adopted by the compounds under these conditions, the samples were illuminated by an intense X-ray beam at two particle accelerators, the German PETRA III and the United States APS synchrotrons.
Dr Laniel commented:
Given the extensive investigations that the La-H system had already underwent, we were surprised to see the formation of this many previously unknown lanthanum hydrides. But the most unexpected result was that their hydrogen-content seemed to greatly vary based on their synthesis condition and pressure—without any noticeable changes in the lanthanum atoms’ arrangement.
This discovery, which is published in Nature Communications, has profound ramifications. Largely due to hydrogen having a single electron, this element cannot directly be detected by X-ray diffraction: a method commonly used to study these hydrides. As such, scientists instead rely on theoretical calculations to determine the position and content of hydrogen atoms in these solids. However, such calculations often assume a single possible configuration of hydrogen atoms for a given arrangement of lanthanum atoms—a hypothesis now demonstrated to be incorrect. This realisation is especially crucial given the very strong dependence of a solid’s superconducting temperature on the hydrogen atoms, i.e. having the wrong model for the hydrogen atoms’ is likely to completely change the calculated superconducting temperature, in turn greatly undermining the reliability of theoretical calculations.
Upon re-analysing published data from other groups, Dr Laniel and collaborators found this hydrogen content variability to be a recurrent phenomenon, thereby generalizing their observations to other systems.
This established hydrogen content variability will undoubtedly provide the impetus for revising theoretical models of high pressure hydrides, ultimately leading to an intimate understanding of their superconductivity and bringing us one step closer to a room temperature superconductor.
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Investment received to support the UK’s academic and industrial strengths in biofilm research and innovation.
The Biotechnology and Biological Sciences Research Council (BBSRC) and Innovate UK will invest £7.5m to support the National Biofilms Innovation Centre (NBIC), expanding on its world-class research and innovation.
The University of Edinburgh is one of NBIC’s four lead research institutions, conducting important research into microbial biofilms across several schools, institutes and research centres, including input from a team at the School of Physics and Astronomy. This research spans a wide range of topics and areas such as bioengineering, biofilm formation, inflammation research, infection control, hygiene and wastewater treatment. The study of biofilms spans disciplines, from understanding how single cells become complex multicellular systems, to collaborative research on how to eradicate biofilms or prevent bacterial infections.
National collaboration
Launched in 2017 by its four lead universities: Edinburgh, Liverpool, Nottingham and Southampton, this UK Innovation and Knowledge Centre has expanded partnerships with 59 research institutions and more than 150 companies across the UK.
NBIC has secured a further £9.5m from the lead universities as well as £6.4m industrial support, taking its Phase 2 funding to a total of £23.4m.
Tackling global challenges
The latest funding will support NBIC’s vision to deliver a global innovation hub by building on its collective strengths to prevent, detect, manage and engineer biofilms. It will enable NBIC to drive the adoption of innovative solutions across industry sectors to address major global challenges including climate change, water safety and improved healthcare. It will also drive step-changes in standards and regulation for novel biofilm solutions that support international trade. Phase 2 will also see NBIC deliver a diverse training programme to equip the biofilm innovation ecosystem with the skills they need both now and, in the future, while also nurturing the talent of tomorrow.
What are biofilms?
Biofilms are central to our most important global challenges, from antimicrobial resistance and food safety to water security. They also provide a significant contribution to both the UK and global economy. In May 2022, a study carried out by NBIC estimated that the value of the markets in which biofilms are involved is worth £45 billion in the UK and $4 trillion globally.
NBIC University of Edinburgh Co-Director, Professor Cait MacPhee, who is based in the School of Physics and Astronomy said:
I am delighted that the pioneering work of NBIC will continue with Edinburgh as one of the core partners. Microbial biofilms play a key role in the biosphere, and are important to environmental efforts such as remediation and the safe maintenance of large-scale infrastructure. They also have an impact, both positive and negative, on a variety of different industries across multiple sectors, including healthcare. We will continue with our work to link the best academic research across the UK to meet urgent industrial needs, for the benefit of end-users and the general public. Anyone with an interest in biofilms is encouraged to get in touch.
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Edinburgh astronomers awarded UK Space Agency funding for international mission.
A consortium of UK astronomers, led by Professor Andy Taylor at the School’s Institute for Astronomy, has been awarded £8 million by the UK Space Agency over the next two years to develop and launch an international space mission to study dark energy and dark matter in the Universe.
The Euclid satellite, expected to be launched in 2023, is a European Space Agency (ESA) flagship mission to image and measure the distance to over 1.5 billion galaxies over 15,000 square degrees of the sky, looking back over half the age of the Universe.
The high-quality images will be carefully processed to generate maps of the distribution and evolution of dark matter and galaxies across the Universe. The maps will be analysed to determine the nature of dark energy, the mysterious phenomena which is driving the accelerated expansion of the Universe.
The UK Space Agency funding will support UK astronomers and computing specialists who are developing advanced methods for the Euclid Science Ground Segment data analysis, and the UK’s dedicated Euclid Science Data Centre, hosted at Edinburgh. The UK consortium is a major component of the Euclid Consortium, a wider European-led network of scientists working on the Euclid mission.
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The School of Physics & Astronomy will take part in the University of Edinburgh Postgraduate Virtual Open Days.
The School of Physics and Astronomy events will consist of presentations and Q&A sessions on the following days:
- Wednesday 16th November: Introduction to MSc Theoretical Physics and Mathematical Physics 14:00-15:00 UK time
- Wednesday 16th November: Introduction to MSc Particle and Nuclear Physics 16:00-17:00 UK time
- Thursday 17th November: Q&A with MSc students and alumni 14:30-15:30 UK time
To book a place visit the Virtual Postgraduate Open Days 2022 page on the University of Edinburgh website.
Congratulations to Dr Carlo Bruno who has been awarded the Young Investigator prize in Nuclear Physics.
The Young Investigator prize in Nuclear Physics is awarded to recognize and encourage promising experimental or theoretical research in nuclear physics, including the advancement of a method, a procedure, a technique, or a device that contributes in a significant way to nuclear physics research.
Carlo Bruno was awarded this prize for his experimental work with low-energy nuclear reactions relevant for astrophysics and his leading role in transferring these experiments into storage rings using radioactive beams.
Carlo graduated from the Università Statale di Milano in Italy, and came to the School’s Institute for Particle and Nuclear Physics for his PhD in Nuclear Astrophysics, which he obtained in 2017. Carlo's research focuses on measuring nuclear reactions of key importance to understand the origin of the elements from the Big Bang to supernovae using heavy ion storage rings at FAIR (Germany). He has played a leading role in creating CARME (CRYRING Array for Reaction Measurements), an extreme vacuum chamber for use in international nuclear and atomic physics experiments.
This prize was established by the International Union of Pure and Applied Physics (IUPAP), which works to assist in the worldwide development of physics, to foster international cooperation in physics, and to help in the application of physics toward solving problems of concern to humanity.
Congratulations to Dr Ross Galloway on who has been awarded the 2022 Institute of Physics Marie Curie-Sklodowska Medal and Prize in recognition of work in developing, using and communicating research-based approaches to active student learning in physics and other disciplines.
The Institute of Physics Marie Curie-Sklodowska Medal and Prize is awarded to those who have made distinguished contributions to physics education.
Dr Ross Galloway’s achievements cover two areas of higher education: firstly, the use, promotion and evaluation of the flipped classroom approach, in which the transfer of knowledge occurs remotely, usually online, and contact with the teacher involves student-centred activity; secondly the use of PeerWise, a revolutionary approach to teaching in which students generate content themselves, including questions and problems to be solved by other students.
Both these areas of work are pioneering in the UK and have been influential in encouraging take up in many other universities. These approaches have also been expanded to developmental sessions in disciplines beyond physics.
Flipped classroom teaching was introduced in 2011 by Dr Galloway as part of the Edinburgh team. He has carried out many evaluation studies, initially focusing on outcome metrics (e.g. using the Force Concept Inventory to evaluate conceptual understanding). More recent studies have included qualitative aspects of student/instructor behaviour to determine what really works and to disperse the false dichotomy between traditional and active learning, instead focusing on which aspects of student activity result in the most valuable learning.
Dr Galloway was part of the first wave of UK engagement with PeerWise from 2010. The distinctive Edinburgh approach was their extensive use of a research-informed scaffold, to allow students to understand the unfamiliar task of writing problems rather than solving them, to build their confidence and to highlight what is effective assessment. He led the deployment of those scaffolding activities and made many improvements over several years. He also carried out research on how students used PeerWise and determined that, when properly supported, students can generate high-quality questions, indicating deep learning and sophisticated understanding of the physics beyond that typically obtained in more passive approaches.
In addition to physics education research, Dr Galloway provides input to the Institute of Physics Degree Accreditation Committee, and provided a major contribution to the revised accreditation approach which is less content-focused and places more emphasis on degree outcomes relating to students' conceptual understanding of physics, problem solving and broader skills.
Machine learning provides a new way of revealing the physical quantities behind the images observed by telescopes.
Machine learning (ML) is a novel method which uses artificial intelligence (AI) to make predictions with data. Artificial intelligence means using computers to do complex tasks, such as recognizing objects from pictures and playing chess. A lot of applications of ML appeared in many different fields of industry and research in recent years. It not only speeds up the process by efficiently dealing with a great amount of data, but also leads to new methods and new findings.
International collaboration
An international group including experts in astronomy research from the University of Edinburgh, Universidad Autonoma de Madrid (Spain), Sapienza University (Italy) and experts in machine learning models from the EURA NOVA company (Belgium), have started a collaboration to provide new and simple ways to infer important physical quantities of clusters of galaxies from multiwavelength images. Recently, they focused on accurate estimates of the mass of galaxy clusters from the Planck satellite microwave images. This study is published in the latest issue of Nature Astronomy.
Measuring galaxy mass
Galaxy clusters are the most massive object that ever formed in our universe, so precisely measuring their masses has very important meanings for many different astronomy studies. In order to obtain its mass from observed images, astronomers have to first process the image by excluding fore/background objects and removing the noises, then different assumptions have to be made to derive the mass from binned image quantities, such as profiles. These assumptions normally oversimplify the state of the real cluster, therefore the mass derived with such methods doesn’t agree with the true mass. This difference is referred to as bias. Furthermore, the whole process is very time-consuming and the clusters have been handled one by one.
Machine learning
The machine learning method proposed by this group overcomes all these problems and can directly get the cluster mass from observed images. And it is very fast - in just a few seconds, over 1000 observed cluster masses are provided. The machine learning model is based on a type of deep learning algorithm known as the Convolutional Neural Networks (CNN), which can get the most important features of an image to connect with a defined quantity. A perfect tool for this task. However, this involves training the model with over 10 thousand images from numerical simulations of galaxy clusters, of which the group used the results from The THREEHUNDRED project, hosted in Universidad Autónoma de Madrid (UAM). They verified the cluster mass from the machine learning model has no bias and has a very small scatter around the true cluster mass. Applying this model to the images observed by the Planck satellite, they provided bias-free cluster masses of over 1000 galaxy clusters.
PhD student Daniel de Andres from UAM has completed most of the work on this project. The paper’s co-leading author, Dr Weiguang Cui, from the School’s Institute of Astronomy commented:
These results as very exciting, and machine learning is proving to be a useful tool which will help us understand our Universe.
Art work produced following a summer collaboration will be exhibited in an Edinburgh gallery this October.
A collaboration involving art students and physics researchers has led to the creation of a series of art work, sculptures and digital graphics, showcasing a range of physics and astronomy concepts.
The exhibition will take visitors on a visual journey across a range of physics research which takes place within the School of Physics and Astronomy. It includes art work depicting the formation and structure of the universe; the application of physics in the study of microorganism growth; and in the use of supercomputers for computationally intensive tasks such as quantum mechanics. It also features portraits of students and researchers.
Three Edinburgh College of Art students collaborated with 20 researchers during the 10 week summer project, brought together by communications and outreach colleagues.
School of Physics and Astronomy organisers commented:
This is a great opportunity to help convey the work which takes place behind lab doors, to communicate complex ideas, and to share some fascinating concepts in a visual format.
The exhibition, called ‘Fusion: Physics X Art’ takes place at Whitespace Gallery in Newington, Edinburgh from Friday 14 to Tuesday 18 October 2022.
The DART - OPTiK team will observe NASA’s asteroid deflection mission from their base in Kenya.
The DART - OPTiK team, which includes a collaboration of researchers from the University of Edinburgh, Science and Technology Facilities Council (STFC), Technical University of Kenya and the Turkana Basin Institute (TBI), set up a portable telescope at the TBI base in Ileret, Kenya and have been taking observations over the past month.
Tonight, they will observe NASA’s Double Asteroid Redirection Test (DART) as the spacecraft launched in November 2021 deliberately collides with its target asteroid. The moment of impact will only be visible from countries around the Indian Ocean, with the dark skies of Ileret making it an excellent vantage point from which to observe this unique event.
DART Mission
The purpose of NASA’s first ever planetary defence test is to demonstrate that the path of an asteroid through space can be changed using a ‘kinetic impactor’: a spacecraft that is deliberately crashed into the asteroid at high speed.
Although the target asteroid is not a danger to Earth, it is expected that the technology being tested can be used, should an asteroid on an Earth-impacting trajectory ever be discovered.
The test will be carried out on a binary asteroid system, which includes a large asteroid (Didymos, 780m diameter) and a smaller moon (Dimorphos, 163m) orbiting it. The DART spacecraft will hit Dimorphos at 14,000 mph, slightly changing its orbit around Didymos. The impact time will be 00:14 BST on Tuesday 27 September, with live images from the spacecraft broadcast online by NASA.
Next steps
The DART- OPTiK team, as well as astronomer teams across the globe, will monitor the orbit of the moon to measure how effective the 'kinetic impactor' experiment was. The team will observe the aftermath of the collision over the coming weeks by monitoring the asteroid’s moon using its lightcurve, and obtain more detailed follow up data using larger telescopes at established observatories in Chile, as part of an international effort.
A related European Space Agency (ESA) mission, Hera, will launch in the coming years to the same asteroid to study the effects of the collision in detail.
Kenyan collaboration
The DART - OPTiK telescope will also be used to do astronomical tests to discern whether the site at Ileret is suitable for a more permanent observatory in the future. Working with the Technical University of Kenya, the Kenyan Space Agency, and the Kenya Optical Telescope Initiative, the team hope to strengthen capacity for local astronomy and facilitate new research in the region.