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Nanotechnologist has a passion for medicine and mentoring

Your first degree was in physics. What sparked your interest in the subject?

I enjoyed physics in high school. My physics teacher, Dan Smalley, instilled a great deal of confidence in me. How he applied the concepts of the field to the real world, initially and greatly sparked my interest. To no-one’s surprise, after also taking the advanced placement (AP) in physics with Smalley, I decided to further pursue physics in my undergraduate career. In both high school and university, I wanted to seek a field that had a mixture of science, health and medicine, but was uncertain of what satisfied that combination. A physics and public health double major at university was the closest combination to meet my interest.

While I was an undergraduate I took organic chemistry courses and I enjoyed them, which led me to apply to graduate programmes in chemistry. I told myself if I got into at least one programme, I would absolutely go for it. Thankfully I did, and I chose to go to the State University of New York at Buffalo (SUNY Buffalo). I chose a principal investigator from listening to one of his seminars, where he spoke about nanomedicine and nanotechnology (encompassing the science and the biological applications) – and I realized that this was the perfect combination for me. I was fortunate to be selected as a graduate student and part of his laboratory based on merit.

What nanotechnologies are you working on?

Currently I am developing a nanoformulation that is suitable for the targeted therapy of hypoxic regions of glioblastoma multiforme – a type of brain cancer. Specifically, my project involves synthesizing a hierarchal nanostructure that consists of ultra-small core shell lanthanide-based nanoparticles that are encapsulated with a PLGA chitosan coating that is then surface modified with a hypoxia targeting moiety.

The aim is to develop a drug delivery system that will be able to cross the blood-brain barrier and target hypoxic regions of glioblastoma. These hypoxic regions have low oxygen levels as well as low pH, and are resistant to chemo- and radiation therapy. Because of that, the tumours tend to metastasize, invade and relapse. My research goal is to improve the oxygen and pH levels within these hypoxic regions, while simultaneously providing dual imaging capabilities (e.g. MRI and CT), therefore, making the chemotherapy more effective.

It is really hard for anything (beneficial or not) to actually cross that blood-brain barrier because that is what keeps out pathogens and bacteria from entering the brain. We developed in vitro models, which suggested that a good percentage of my nanoparticles have crossed the barrier. The next step is determining if it works in vivo with animal studies.

You mentioned that your principal investigator made a positive impression on you from the start; what do you enjoy about working in his lab?

Part of it is how he presents his research; thoroughly breaking down complex ideas. Working in his laboratory, I am mentored by physicists, biologists, engineers, medical doctors and a variety of different experts. His laboratory is multifaceted, and the research projects conducted have a variety of interdisciplinary chemistry topics that overlap with medicine. The overlap with medicine is my priority interest, again incorporating science and medicine.

You founded Black in Nanotech Week, which ran for the first time in December 2020. Can you describe the event?

The virtual event included conference-style presentations from faculty members so participants could learn about different applications of nanotechnology. We ran Q&A sessions with experts from academia and industry and we also had graduate admission recruiters detailing their nanotechnology programmes, degree options offered, the application process, and the eligibility requirements. Plus of course, participants shared their own research in nanotechnology. One of the highlights of the event was guest speaker Hadiyah-Nicole Green, who is one of few Black women to have earned a physics doctoral degree and the first person to cure cancer using laser nanotechnology. She was willing to share her experiences and resources with the participants.

Black in Nanotech Week ended on a Saturday with a self-care event: a 45 minute yoga and meditation session. As scientists and as humans in general, we tend to not take breaks from our research or from our work. So, it is always important to step back and take care of ourselves and our mental health.

What is next for Black in Nanotech Week?

We plan to expand Black in Nanotech into an organization that highlights and celebrates Black voices in science and specifically nanotechnology. Our goal to is emphasize the importance of representation to younger individuals who are in middle and elementary school. To expand the percentage of Black individuals in STEM, recruitment efforts must start at the younger educational level.

Mentorship is clearly important to you, is that why you decided to start Black in Nanotech Week?

Yes, as I move forward with my career, I continue to find myself too often the only Black woman in a room full of bright minds, especially in nanotechnology. Unfortunately, there are very few who look like me in the field, and I, as a Black woman, want to help pave the way for other women of colour who are interested in nanotechnology. Thus, being a STEM diversity advocate is my way of changing the cold climate that marginalized groups consistently face in the scientific fields.

What are some of the challenges you come across while mentoring?

One of many problems is that we tend to start mentoring undergraduates when they are choosing to go to graduate school, but my goal is to begin even younger. Under-representation starts before the undergraduate and high school levels and I think mentoring should begin in elementary school – because that is where students in some communities are not seeing the opportunities in STEM.

When I was in high school, I was unaware of the many different scientific fields. I knew the basic subjects of chemistry, biology and physics, but STEM is more diverse than that.

You are also working on a project that is aimed specifically at Black women; can you tell us about STEMNoire?

I had the great opportunity to be on the planning council for STEMNoire, which is a research conference and a holistic wellness retreat for Black women in STEM. We realized that we wanted a conference that provides an open space to talk about our journeys, our successes, our failures and the obstacles that we have overcome without delegates feeling that they are in a minority. We wanted a group where Black women are the majority and are comfortable enough to share everything that we have experienced in our scientific fields.

In-person conferences are a bit difficult at the moment; are you planning online events or STEMNoire?

Yes, our inaugural conference was planned for summer 2020 in San Juan, Puerto Rico, but the COVID-19 pandemic occurred. Instead, we held a one-week virtual conference highlighting Black women in STEM and related fields in July 2020. Our official conference will be held in June 2021. The content is yet to be finalized. Participants can expect a variety of events, including various keynote speakers, poster sessions, and oral presentations – focusing on Black women’s current research work, expertise and experiences within their respective fields.

And for you personally, what are your plans after you finish your PhD?

I hope to be in a laboratory still working in nanotechnology – ideally in a pharmaceutical company or industry where I continue cancer-related research because it has definitely touched home. Many members of my family are cancer survivors including my dad, brother and grandmother. Thus, cancer research will always be dear to my heart. I would love to keep going in that field.

Superconductivity and quantum Hall effect coexist in novel nitride material

Large magnetic fields are usually a killer for superconductivity, but researchers in the US have now fabricated a material that simultaneously superconducts and exhibits the quantum Hall effect – a phenomenon that requires a strong magnetic field. The new material, made from nanoscale layers of gallium nitride and niobium nitride, could be used for “topological” quantum computing and to make more energy-efficient electronic devices.

The quantum Hall effect occurs when a current passing along the length of a thin conducting sheet gives rise to an extremely precise voltage across opposite surfaces of the sheet. This voltage only occurs when a strong magnetic field is applied perpendicular to the sheet, and it is quantized – that is, it can only change in discrete steps. Another consequence is that electronic states on the surface of the two-dimensional (2D) sheet are said to be “topologically protected”. This protection arises because electrons in these “edge” states can only travel in one direction, and they also steer around imperfections or defects in the material without backscattering. Since backscattering is the main energy-dissipating process in electronic devices, such protected states could be useful components in next-generation energy-efficient devices.

Another important benefit is that an edge electron with a certain momentum cannot scatter into a state with opposite momentum (or spin) since to do so it would have to flip its spin. Topologically-protected states might thus be ideal for quantum-computing applications in which defects usually destroy information carried in the spin state of electrons.

Topologically protected superconducting electron states

In recent years, researchers have been trying to create heterostructures – 2D semiconductors grown on superconductors – in which the states of the electrons that make up the superconducting current are also topologically protected. This supercurrent comes from electrons with opposite spins that have paired up and can move through the material without any resistance below a certain critical temperature. Materials that can accommodate such supercurrents are limited, however, because the magnetic field required to produce the quantum Hall effect destroys superconductivity – either by breaking up the electron pairs or by trying to make both electron spins align in the same direction.

Modified growth process

In the new work, researchers at Cornell University, the Naval Research Laboratory, and Qorvo Inc. engineered heterostructures from nanoscale layers of semiconducting gallium nitride (GaN) on superconducting niobium nitride (NbN). These two materials have similar crystal structures and chemical properties and previous work by the same team showed that they can be made into a layered heterostructure using a technique called epitaxial growth.

These materials are routinely employed in light-emitting diodes and transistors for products like smartphones and home lighting, and the team chose them in part because they are robust. However, they do contain more structural defects than other technologically-important materials like silicon. To reduce the number of defects, and thus create a higher-quality heterostructure, the researchers modified the growth process employed in their earlier study. This modification also allowed them to precisely engineer the position of the electrons in the GaN atop the NbN.

Collective electron excitations break down quantum Hall effect in graphene

Narrow “window” of temperatures and magnetic fields

Using measurements of resistance versus applied gate voltage at temperatures of 390 mK, the researchers showed that superconductivity in the improved NbN layer could survive applied magnetic fields as high as 17.8 Tesla. Meanwhile, the improved GaN semiconductor was of high enough quality to exhibit the quantum Hall effect at lower applied magnetic fields of 15 T. “Both these improvements mean the quantum Hall effect and superconductivity can occur at the same time in the heterostructure over a certain ‘window’ of temperatures and magnetic fields (that is, below 1 K and between magnetic fields of 15 to 17.8 T),” study lead author Phillip Dang tells Physics World.

According to the team, the new GaN/NbN heterostructure could be used in quantum computing and low-temperature electronics. Reporting their work in Science Advances, the researchers say they now plan to further investigate the interaction between superconductivity and the quantum Hall effect in this material.

‘Twistoptics’ produces a tunable nonlinear optical response

Researchers in the US have shown that 2D materials can be used to create tunable optical second-harmonic generation. They achieved this by rotating layers of hexagonal boron nitride relative to each other, creating an efficient and controllable optical response. This could have advantages in a range of laser-based applications, the researchers say, and could provide a compact way of generating entangled photons for quantum information processing and computing.

Optical frequency conversion is a nonlinear process where materials are used to generate light at different colours, or frequencies, to that inputted. This can be exploited to generate light at frequencies for which there is no convenient laser source and is used for many applications, such as quantum photonics, super-resolution imaging and optical sensing. Second-harmonic generation is a common type of frequency conversion in which two input photons are combined to produce one photon with twice the energy.

The ubiquitous green laser pointers, for example, use second-harmonic generation to frequency double infrared lasers to green. This is simpler and cheaper than producing a green laser. But like most nonlinear optical processes, it relies on crystals. The rigid structure of crystals makes controlling the output signal and changing any aspect of it difficult because you can’t easily adjust their optical properties. “If you wanted to make [a green laser pointer] a different shade of green, for example, that would be really hard,” explains James Schuck, a mechanical engineer at Columbia University.

As well as adjusting the output frequency of a second-harmonic generation response, you might also want to modulate it, to make it brighter or dimmer. You can do this by adjusting the laser source, but it would be preferable to have a constant source and adjust the nonlinear response of the material itself. The output can also be modulated by applying a voltage to the crystal or hitting it with an ultrafast laser pulse.

However, Shuck and his colleagues wondered whether better tunable second-harmonic generation could be achieved using methods developed for “twistronics”, a technique in which two layers of 2D materials are twisted, or rotated, relative to each other. This rotation changes the electronic properties of the materials, with researchers being particularly interested in its effect on superconductivity and insulation. “It wasn’t a big leap for us to say well you probably change the optical properties too,” Shuck says.

In work described in Science Advances, the researchers rotated layers of hexagonal boron nitride to achieve highly tunable second-harmonic generation. They found that this technique enabled them to modulate the output intensity of a second-harmonic generation that was 10 times larger than achievable using electric pulses or lasers applied to optical crystals. This high tunability also persisted over a broad band of frequencies in the visible spectrum.

To rotate two layers of boron nitride relative to each other, the researchers etched the top layer into cog-like shapes, or micro-rotators. They then used an atomic force microscope (AFM) to push on and shift this top layer. This allowed them to dynamically tune the symmetry of the layers, adjusting the optical response.

Experiment schematic — Boron nitride crystals are etched into micro-rotator shapes and pushed by AFM tips. (Courtesy: Nathan R Finney and Sanghoon Chae/Columbia Engineering)

The researchers have named this technique “twistoptics”. The concept works with many other 2D materials, Shuck says. However, boron nitride is particularly good as it can produce a second-harmonic generation response over a wide range of input frequencies.

Shuck tells Physics World that twistoptics could be used to generate entangled photons for applications in quantum optics and quantum information. This process is essentially a reverse of second-harmonic generation. A high-energy photon is sent into the material and splits into two photons. And these photons are quantum entangled.

There are crystals available that can perform this down-conversion and produce entangled photons, but they are quite large. By stacking multiple layers of 2D material you could produce many twisted interfaces to create a very efficient nonlinear optical response in a very thin material, Shuck says. And as well as reducing the physical size of the material, this would provide more control over the output frequencies and intensities.

“We are trying really hard to see if we can create entangled photons,” Shuck tells Physics World.

Space wine, ESA astronaut call, April Fool’s round-up

In November 2019, 12 bottles of Chateau Petrus 2000 – a wine from Bordeaux, France, which would set you back a few thousand pounds per bottle — hitched a ride to the International Space Station (ISS). The bottles spent around 14 months in the microgravity environment before returning to Earth in January where they were then sent to the Institute of Vine and Wine Science at the University of Bordeaux to be analysed – and, of course, tasted. On 1 March, a bottle was opened and blindly tasted by 12 connoisseurs alongside one bottle from the cellar. Now the team have announced their highly anticipated preliminary results, finding that the wine on the ISS had “heighted floral characteristics” and was one to three years further “evolved” compared to the bottle that had stayed firmly to the ground. The team now plan to take a closer look at the biochemical properties of the wine that has been in space, followed, of course, by more tasting.

Still on space, ever dreamed of becoming an astronaut? Well, now is your (latest) chance. Applications are open for the European Space Agency’s 2021 astronaut selection. As well as recruiting new members to the astronaut corps, ESA has also issued a vacancy for a “parastronaut”, which will involve taking part in a feasibility study for astronauts living with specific physical disabilities. “Representing all parts of our society is a concern that we take very seriously,” says David Parker, ESA’s director of human and robotic exploration. “Diversity at ESA should not only address the origin, age, background or gender of our astronauts, but also perhaps physical disabilities.” The closing date for applications is 28 May and if chosen you will then begin a gruelling six-stage selection process. Successful candidates will be announced in October 2022. Ad Astra!

And finally, in case you missed yesterday’s April Fool’s offerings on the arXiv preprint server then here is a small selection: pandemic dark matter, emotional trends in the repertoire of Taylor Swift, using artificial intelligence to shed light on the Jaffa Cake and the existential threat of future exoplanet discoveries. CERN, meanwhile, proposed a “space elevator” accelerator.

Recognizing religious diversity in physics

A Muslim, a Christian and a Hindu walk into a lab… It sounds like the start of a joke, but this is what happened in late 2017 when I and two colleagues met to talk about our experiences of having religious beliefs and working in science. The National Physical Laboratory (NPL) in the UK has respect and inclusivity embedded in its core values and, like many scientific organizations, is learning to value and support equality, diversity and inclusion. What started as a little chat in the lab soon transformed into the NPL’s faith and religious diversity group that now supports people with all beliefs to thrive in the workplace.

My colleagues and I often talk about “enabling everyone to bring 100% of themselves to work”. When it comes to religion this mostly concerns practical adjustments to support inclusivity: providing a prayer room and ablution facilities on site; considering religious dietary requirements for meetings; as well as taking note of religious sensitivities when choosing suitable venues for events. Yet there is also a wider need for education. Many of us are unaware of the different religious holidays or observances that might affect our colleagues and are afraid of unwittingly causing offence by asking about others’ beliefs or practices.

Changing attitudes

A British Social Attitudes survey in 2019 found that 48% of the UK population identifies as religious and that since 1983 there has been a decline in the proportion of Christians, an increase in the non-religiously affiliated, as well as a rapid rise in the Muslim population, along with other minority religions (up from 2% to 9%). In other words, the beliefs and worldviews of the UK population are becoming more diverse as we move away from a predominantly Christian population to a more mixed one. Yet in this regard – as in other aspects of diversity – the UK scientific community is strikingly out-of-step with society. Indeed, a report from Rice University in 2016 found that just 27% of UK scientists identify as religious compared with 47% of the general population (Socius 10.1177/2378023116664353).

Neither society nor scientific pursuits stand to benefit from being out-of-step with each other

So, what is keeping religious people away from science? It is tempting to follow the Enlightenment philosophy that places science and religion in conflict: “as science advances, religion declines”. But that is far too simple. The Rice report compares eight countries, finding that the disparity between scientists and the general population who identify as religious is small in nations such as Turkey and India, while in others such as Taiwan and Hong Kong religious people are even over-represented in science. That picture is very different from the UK and other western countries where the religiously affiliated are strikingly under-represented. The report also finds that most scientists do not believe there is a conflict between science and religion – instead it being more a societal issue than a philosophical one.

Irrespective of the reasons why religious people are under-represented in science, which are no doubt manifold and complex, I believe that neither society nor scientific pursuits stand to benefit from being out-of-step with each other. Rachel Brazil’s insightful Physics World article “Fighting flat-Earth theory” traces the rise of belief in a flat Earth back to religious convictions. It stands as a warning that we need to build bridges between scientific and religious communities rather than allowing the divide to widen further. In a society that increasingly recognizes the value of diversity, it is worth reflecting on the history of science to see that no single religion or worldview has a monopoly on scientific progress. Even a cursory glance reveals profound contributions to science from individuals representing the full range of religious and non-religious worldviews, both historic and contemporary. Clearly this diversity of thinking is of enormous and proven value to science and technology, and is something to be treasured, nurtured and encouraged.

An open environment

At NPL we have made “inter faith week” a regular fixture in our calendar. This is a national initiative that supports and encourages constructive interactions between people with different beliefs to build relationships and mutual understanding, recognizing common values as well as differences. We also encourage colleagues to share their experiences of how their beliefs affect their work and invite guest speakers to talk about a subject relating science to religion. Over the past three years we have had talks on the relationship between artificial intelligence and religion, the role of faith in science and the health benefits of intermittent fasting. Each year we find that there is an enormous desire to learn about and discuss these topics.

The very nature of religious diversity is that we fundamentally and profoundly disagree with one another. It is no secret that our different worldviews are mutually incompatible. So, we do not shy away from disagreement and debate within a respectful and constructive context, but we come together within the scientific community to tackle discriminatory behaviours. Ultimately, we are united by the thing that brought us together in the first place: science.

Inspiring young children to careers in science, the physics and economics of heat pumps

Many children are naturally curious and have vivid imaginations – two qualities that make them well-suited for careers in physics. So why do many children eschew science when they are asked what they want to be when they grow up? That is a research interest of Carol Davenport at the UK’s Northumbria University, who talks about how to broaden the career aspirations of children in this episode of the Physics World Weekly podcast.

The move to greener sources of energy should create many new job opportunities for future physicists. Heat pumps offer a much more energy efficient way to heat and cool buildings, and Physics World columnist James McKenzie explains how the technology could play an important role in helping the UK meet its commitment to a net-zero-carbon economy by 2050. He explains how heat pumps work and describes what it is like to live in a house that is heated by the technology.

Quantum computer has the edge for NP verification

One of the main goals in quantum computing is to experimentally demonstrate that a quantum machine can perform some computational task faster than a classical one. A team of researchers based in France and the UK has now done just that using a simple quantum photonics experimental set-up. Their work shows that it is possible for a quantum computer to verify solutions to problems classified as NP-complete using a so-called interactive proof protocol and only minimal, unverified information about the solution.

The work is among several recent milestones in demonstrating quantum advantage. In 2019, Google claimed to be the first to the finish line with their 53 programmable superconducting qubit (quantum bit) set-up. More recently, a team in China announced that they had successfully performed “boson sampling”, a task known to be hard for a classical computer. Unlike these previous results, however, the new research, which is published in Nature Communications, not only demonstrates quantum advantage but also promises to be useful in applications like secure quantum cloud computing.

NP verification

Although NP-complete problems are hard to solve efficiently, once solutions are found, they can be verified trivially. The challenge that the team at CNRS (the French National Centre for Scientific Research) and the University of Edinburgh focused on occupies a middle ground between the two: verifying the solution to an NP-complete problem when provided with only a part of that solution.

When the size of the message containing the partial solution, or proof, is fixed, it can be shown that a classical protocol for verifying the solution will take an amount of time that scales exponentially with the size of the message. For the quantum protocol, in contrast, the scaling is polynomial. This means that for large message sizes, a quantum computer would take minutes to verify the solution while a classical one could take years.

The algorithm the researchers use to demonstrate this is known as an interactive proof protocol. Here, one component of the experimental set-up acts as a “prover”, using coherent light pulses to send partial solutions to the NP-complete problem in the form of a quantum state. The second component fills the role of the “verifier”, deciding with high accuracy whether the solution is correct based on the limited information given. When certain bounds are placed on the expected accuracy of the verifier, as well as the protocol’s speed and efficiency in terms of the amount of information that can be communicated throughout the interactions, it is possible to demonstrate that the quantum algorithm far outperforms any classical attempts at doing the same.

Quantum cloud computing

By showing that a quantum algorithm can verify solutions to NP-complete problems efficiently, the result could allow for new applications in secure remote quantum computing. A client with a rudimentary quantum machine could, for example, verify information they receive from a powerful quantum server without ever having access to the full solution. Such proof systems could then contribute to protocols like secure identification, authentication or even blockchain in a future quantum Internet. “In the current era of increasing focus on data privacy and secure computing, our demonstration provides yet another compelling piece of evidence that quantum computers can outperform their classical counterparts in achieving secure solutions,” adds Niraj Kumar, an Edinburgh researcher and a co-author on the paper.

Physics in the pandemic: ‘We’ve been surprised at how easy it’s become to do high-level experiments from our homes’

I’m part of a team that provides support for computer, control and data acquisition systems for plasma operations at the DIII-D tokamak. Before the pandemic, I would arrive at the fusion research facility at around 7 each morning to check the readiness of our systems before attending a standing-room-only meeting. Other attendees included physicists overseeing and participating in the experiment, plus representatives from operations support groups in power, vacuum, heating, water, cryogenics, diagnostics and computer systems – as many as 60 people in total.

After that, I would spend most of my day in the DIII-D control room. This was a busy environment, with every seat taken and all eyes focused on large display monitors showing live tokamak status and experiment results. The physics session leader overseeing the experiment would sit at the front, working closely with other physicists and with the chief operator who oversees tokamak operations and safety. At nearby stations, other groups of scientists would monitor diagnostics and analyze results. These individuals would be in close contact with the session leader, often having direct personal conversations to provide immediate assistance and feedback.

In addition to the staff in the main control room, we had teams spread throughout the facility to support various aspects of the tokamak’s operation. These groups kept in contact via a direct overhead paging system, landline phones and walkie talkies. Doing experiments on DIII-D requires input from a lot of people, so there could be as many as 120 of us in the facility during a day of experiments.

From hands-on to mostly remote

The pandemic changed all of this. Since the start of restrictions, most fusion research staff have been working offsite, with only a few allowed in the DIII-D facility. We were, however, fortunate in that DIII-D staff had extensive experience in working with other tokamaks across the world and even, in at least one case, controlling a tokamak remotely from San Diego. This knowledge gave us a good base on which to build.

The first step was to provide offsite staff with access to the full set of computer systems and applications needed to run experiments in a secure manner. Since quite a few of these tools control critical pieces of hardware, it was crucial that access was restricted to authorized personnel.

A sign reading 'DIII-D National Fusion Facility' with trees and grass in the background — **A rare sight**: Since the beginning of the pandemic, the DIII-D facility has taken steps to limit the number of staff who have to be physically present at its site in San Diego, California. (Courtesy: General Atomics)

The next step was to create a virtual control room that would allow offsite staff to see and hear the same information they were accustomed to having at the facility. We did this by adding to and improving upon an existing set of web-based displays showing live tokamak status information, real-time signal plots, and a tokamak plasma cross-section animation. We also set up two live camera feeds of the DIII-D control room along with broadcasts of the on-site paging system.

The final and most crucial step in setting up remote operations was to provide a communications infrastructure that could accommodate coordination amongst a large and varied group of individuals working both onsite and offsite. Initially, we tried having everyone in a single Zoom meeting room, but this quickly ran into problems. Communications during experimental operations tend to be very ad hoc and dynamic, and as the number of people in the meeting grew, it became very difficult to manage these kinds of conversations. With close to 100 people signing on, it was hard for individuals to break into general discussions or for smaller groups to have conversations amongst themselves – the friction involved in jumping from conversation to conversation was just too high.

A new use for a gaming app

Instead, we settled on Discord, an application that is mainly used in the video-gaming community. Our Discord server provides a platform for DIII-D group members to communicate on an as-needed basis, as well as listen in and participate in the main experiment. Discord’s architecture makes it possible for many users to “meet” in one place, while also allowing them to break off into smaller groups and move between separate dedicated channels. It proved very effective in bringing all the different DIII-D groups together.

Another problem that Discord helped solve related to contacting users working offsite. Thanks to Discord, people who could no longer answer phones in their offices could be reached easily by voice or text while signed into the app. While the initial adaptation and deployment was a challenge – we had a large number of users requiring access to Discord, and they all needed to be registered and trained in order to fit it into their day-to-day methods of conducting business – it has been hugely beneficial to our operations.

Telecommuting to a tokamak

A photograph of the DIII-D tokamak taken before the pandemic. It shows four people in hard hats (but not masks) working closely together on the tokamak. — **Hands on**: A pre-pandemic panorama of the tokamak at the centre of the DIII-D National Fusion Facility. (Courtesy: General Atomics)

Thanks to our remote-operations solutions, most of our scientific and support staff can, in effect, run the tokamak without having to step outside their homes. Scientists can analyze all aspects of the plasmas and status of the tokamak in real time, while coordinating and collaborating with one another using tools such as Discord and Zoom.

Of course, there are still some activities that require onsite staff to touch hardware in the lab. These include calibrating equipment at the start of each day, performing routine maintenance, and making necessary repairs and upgrades. To limit the number of people engaged in these tasks, we provided onsite workers with tablets equipped with cameras and microphones to connect them with remote experts who could offer guidance in repairs or adjustments needed to hardware.

What’s missing – and what isn’t

Although the face-to-face camaraderie of working alongside colleagues in our quest for fusion has been much missed, we’ve found ways to adjust. We’ve also been a bit surprised at how easy and natural it’s become to do high-level physics experiments from our homes. In some cases, the transition to remote operations has even made our work more efficient. One example is the improved communications between different groups. It is now much more straightforward to find and contact the right people to resolve an issue thanks to our new Discord-based central communication system.

It remains to be seen whether some people will grow less inclined to sign on to communications tools such as Discord as more staff become available onsite. However, the improvement in overall communications efficiency it offers should give people an incentive to continue using it.

More generally, it is easy to see how many of the tools developed to support remote operations during the pandemic could be left in place as more staff return to onsite working. The live web-based status displays, real-time plots and control room videos are as useful and effective to users working from home as those working from their own offices. These tools give us greater flexibility and efficiency in supporting operations and monitoring the experiment.

Shape-shifting biomaterial could transform 4D tissue engineering

Materials that controllably change shape over time – often called four-dimensional (4D) materials – are excellent candidates for advanced tissue engineering applications. Many 4D materials, however, have only been loaded with low concentrations of cells, potentially limiting their use in regenerative medicine.

To address this problem, researchers from the University of Illinois at Chicago have developed a 4D biomaterial system using two types of biocompatible hydrogels. Manufactured as sheets, the materials curl into tubes when exposed to water. Each new hydrogel can support cell densities as high as 100 million cells/mL – approaching the same order of magnitude as that found in developing and healing tissues.

“Using a high density of cells can be advantageous in tissue engineering as this enables increased cell–cell interactions that can promote tissue development,” explains lead author Eben Alsberg in a press statement. The researchers describe their work in Advanced Functional Materials.

Water-activated shape change

Tissue development is a highly dynamic process. Clusters of cells are organized through a series of complex architectural changes until the final tissue structure is formed. It may therefore be beneficial for tissue engineered scaffolds to respond to, and even replicate, the geometric changes that occur within the tissue on the same time scale.

This is where shape-shifting materials shine. The researchers hypothesized that stacking hydrogels with different swelling rates would create a 4D material that gradually changes shape as it absorbs water. By controlling the spatial distribution of each hydrogel throughout the scaffold, the extent of swelling (and therefore shape change) could then be regulated over time.

First, the team investigated the swelling properties of two biocompatible hydrogels: oxidized and methacrylated alginates (OMAs) and methacrylated gelatin (GelMA). They not only found that OMAs swell more than GelMA, but that OMA expansion could be further augmented by altering its chemistry. The higher the degree of OMA oxidation, the faster its degradation rate and the more it expands.

Next, the researchers submerged a series of flat, bilayered OMA/GelMA scaffolds in cell culture media and monitored their subsequent deformation. Over the course of 21 days, each scaffold curved into a “C” shape, with some forming closed circles or even rolled, spiral-like structures. In each case, the OMA layer dictated the overall shape change because it absorbed water the fastest. What’s more, the extent of curling could be controlled by changing the thickness of the OMA layer or varying the OMA oxidation level.

The material is also compatible with techniques like photolithography and bioprinting, which allowed the team to create 4D hydrogels with more complex starting geometries and shape transformations.

“Using our bilayer hydrogels, we can control how much bending the material undergoes and its temporal progression,” says first author Yu Bin Lee.

Research team — The team from the University of Illinois at Chicago (from top left): Yu Bin Lee, Oju Jeon, Sang Jin Lee, Aixiang Ding, Derrick Wells and Eben Alsberg. (Courtesy: Eben Alsberg)

Record-breaking cell encapsulation

To test the impact of cell density on 4D shape change, the researchers loaded each hydrogel layer with varying concentrations of fibroblast cells or stem cells. The material maintained its rolled structure after three weeks, even at extremely high cell densities (1.0 × 10⁸ cells/mL).

Prior to this study, the highest reported concentration of cells encapsulated within a shape-changing material was 1.0 × 10⁷ cells/mL – 10 times lower than that achieved by the team in this work. Both cell types remained viable throughout the 21-day period. Importantly, the stem cells could perform normal cellular activities like differentiation.

The researchers hope that the material could be used to mimic a range of target tissues that have varied cell concentrations. “This system holds promise for tissue engineering, but may also be used to study the biological processes involved in early development,” says Lee.

Measuring methane from cows: the April 2021 issue of Physics World is now out

Image of cover of April 2021 issue of Physics World showing cows — Cattle battle: how to measure and combat methane emissions from cows

“Consider a spherical cow” is probably the start of a joke about the abstractions of theoretical physicists. But in the real world, cows are no laughing matter.

That’s because when they chomp on grass and straw, cows produce methane, which they belch out. And while that might be pleasant for the cow, it’s not great for the environment given that methane is a potent greenhouse gas.

Studying bovine emissions and trying to reduce the amount of methane they emit is therefore a clever, short-term solution to climate change.

But the tricky bit is measuring how much methane cows produce in the first place – especially from a herd of them.

As Michael Allen explains in the cover feature of the April 2021 issue of Physics World magazine, physicists have turned to drones carry spectrometers and even “frequency combs” – sensitive, laser-based systems that bagged a Nobel prize.

If you’re a member of the Institute of Physics, you can read the whole of Physics World magazine every month via our digital apps for iOS, Android and Web browsers. Let us know what you think about the issue on Twitter, Facebook or by e-mailing us at pwld@ioppublishing.org.

For the record, here’s a run-down of what else is in the issue.

• Pulled paper slows hunt for Majorana – Physicists remain convinced that the elusive Majorana particle will be found, despite the retraction of a paper claiming its discovery, as Alexander Hellemans reports

• China powers ahead in neutrino physics – Ling Xin examines the legacy of the recently closed Daya Bay Reactor Neutrino Experiment on neutrino physics, US–China collaborations and future neutrino facilities

• Changing bad exam habits – Paolo Elias says that the COVID-19 pandemic offers the chance to revamp how we assess physics students at school and college

• A decade of success – James McKenzie celebrates some of the firms that have won business innovation awards from the Institute of Physics over the last 10 years

• Crisis in a lockdown – Robert P Crease describes how news of a radiation leak at a US neutron facility was handled in today’s online, networked and locked-down world

• Battling bovine belching – Cutting methane production from livestock is considered vital to climate change mitigation, with lots of research focusing on how animals breed and are fed. But physicists are playing their part too by developing ways to measure the emissions from cattle, using techniques such as spectroscopic analysis and aerial sampling, as Michael Allen discovers

• A century of nuclear isomers – One hundred years after “nuclear isomers” were first discovered, Philip Walker and Zsolt Podolyák pick five examples of these long-lived, excited nuclear states to show why they are so important in medical physics and beyond

• Solar superpower – Multi-layered solar cells stand on the brink of 50% efficiency, but the practical benefits of such high-efficiency cells are more likely to be realized in space than on Earth, as Richard Stevenson explains

• Mission to Mars – Andrew Glester reviews Dream Big: How to Reach for Your Stars by Abigail Harrison

• The surprises essential to life – David Appell reviews Seven Pillars of Science: the Incredible Lightness of Ice, and Other Scientific Surprises by John Gribbin

• Living in a materials world – Materials scientist Arnab Basu, head of radiation-detection technology developer Kromek, talks to Tushna Commissariat about founding a spin-off, the challenges of COVID-19 and looking to the future

• Ask me anything – Tim Gershon is a professor of physics at the University of Warwick, UK.

• Counting muons in schools – Andrew Ferguson on how lockdown didn’t stop him with his project to get school pupils into particle physics

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