EPFL scientists have developed AI-powered nanosensors that let researchers track various kinds of biological molecules without disturbing them. Courtesy: École polytechnique fédérale de Lausanne (EPFL)
If you look at the big orange dot (representing the nanosensors?), you’ll see those purplish/fuschia objects resemble musical notes (biological molecules?). I think that brainlike object to the left and in light blue is the artificial intelligence (AI) component. (If anyone wants to correct my guesses or identify the bits I can’t, please feel free to add to the Comments for this blog.)
Getting back to my topic, keep the ‘musical notes’ in mind as you read about some of the latest research from l’École polytechnique fédérale de Lausanne (EPFL) in an April 7, 2021 news item on Nanowerk,
The tiny world of biomolecules is rich in fascinating interactions between a plethora of different agents such as intricate nanomachines (proteins), shape-shifting vessels (lipid complexes), chains of vital information (DNA) and energy fuel (carbohydrates). Yet the ways in which biomolecules meet and interact to define the symphony of life is exceedingly complex.
Scientists at the Bionanophotonic Systems Laboratory in EPFL’s School of Engineering have now developed a new biosensor that can be used to observe all major biomolecule classes of the nanoworld without disturbing them. Their innovative technique uses nanotechnology, metasurfaces, infrared light and artificial intelligence.
To each molecule its own melody
In this nano-sized symphony, perfect orchestration makes physiological wonders such as vision and taste possible, while slight dissonances can amplify into horrendous cacophonies leading to pathologies such as cancer and neurodegeneration.
“Tuning into this tiny world and being able to differentiate between proteins, lipids, nucleic acids and carbohydrates without disturbing their interactions is of fundamental importance for understanding life processes and disease mechanisms,” says Hatice Altug, the head of the Bionanophotonic Systems Laboratory.
Light, and more specifically infrared light, is at the core of the biosensor developed by Altug’s team. Humans cannot see infrared light, which is beyond the visible light spectrum that ranges from blue to red. However, we can feel it in the form of heat in our bodies, as our molecules vibrate under the infrared light excitation.
Molecules consist of atoms bonded to each other and – depending on the mass of the atoms and the arrangement and stiffness of their bonds – vibrate at specific frequencies. This is similar to the strings on a musical instrument that vibrate at specific frequencies depending on their length. These resonant frequencies are molecule-specific, and they mostly occur in the infrared frequency range of the electromagnetic spectrum.
“If you imagine audio frequencies instead of infrared frequencies, it’s as if each molecule has its own characteristic melody,” says Aurélian John-Herpin, a doctoral assistant at Altug’s lab and the first author of the publication. “However, tuning into these melodies is very challenging because without amplification, they are mere whispers in a sea of sounds. To make matters worse, their melodies can present very similar motifs making it hard to tell them apart.”
Metasurfaces and artificial intelligence
The scientists solved these two issues using metasurfaces and AI. Metasurfaces are man-made materials with outstanding light manipulation capabilities at the nano scale, thereby enabling functions beyond what is otherwise seen in nature. Here, their precisely engineered meta-atoms made out of gold nanorods act like amplifiers of light-matter interactions by tapping into the plasmonic excitations resulting from the collective oscillations of free electrons in metals. “In our analogy, these enhanced interactions make the whispered molecule melodies more audible,” says John-Herpin.
AI is a powerful tool that can be fed with more data than humans can handle in the same amount of time and that can quickly develop the ability to recognize complex patterns from the data. John-Herpin explains, “AI can be imagined as a complete beginner musician who listens to the different amplified melodies and develops a perfect ear after just a few minutes and can tell the melodies apart, even when they are played together – like in an orchestra featuring many instruments simultaneously.”
The first biosensor of its kind
When the scientists’ infrared metasurfaces are augmented with AI, the new sensor can be used to analyze biological assays featuring multiple analytes simultaneously from the major biomolecule classes and resolving their dynamic interactions.
“We looked in particular at lipid vesicle-based nanoparticles and monitored their breakage through the insertion of a toxin peptide and the subsequent release of vesicle cargos of nucleotides and carbohydrates, as well as the formation of supported lipid bilayer patches on the metasurface,” says Altug.
This pioneering AI-powered, metasurface-based biosensor will open up exciting perspectives for studying and unraveling inherently complex biological processes, such as intercellular communication via exosomesand the interaction of nucleic acids and carbohydrates with proteins in gene regulation and neurodegeneration.
“We imagine that our technology will have applications in the fields of biology, bioanalytics and pharmacology – from fundamental research and disease diagnostics to drug development,” says Altug.
Researchers at the University of Ottawa have debunked a myth, one involving metals and light according to a March 1i, 2021 news item on phys.org (Note: Links have been removed),
Researchers at the University of Ottawa have debunked the decade-old myth of metals being useless in photonics—the science and technology of light—with their findings, recently published in Nature Communications, expected to lead to many applications in the field of nanophotonics.
“We broke the record for the resonance quality factor (Q-factor) of a periodic array of metal nanoparticles by one order of magnitude compared to previous reports,” said senior author Dr. Ksenia Dolgaleva, Canada Research Chair in Integrated Photonics (Tier 2) and Associate Professor in the School of Electrical Engineering and Computer Science (EECS) at the University of Ottawa.
“It is a well-known fact that metals are very lossy when they interact with light, which means they cause the dissipation of electrical energy. The high losses compromise their use in optics and photonics. We demonstrated ultra-high-Q resonances in a metasurface (an artificially structured surface) comprised of an array of metal nanoparticles embedded inside a flat glass substrate. These resonances can be used for efficient light manipulating and enhanced light-matter interaction, showing metals are useful in photonics.”
“In previous works, researchers attempted to mitigate the adverse effect of losses to access favorable properties of metal nanoparticle arrays,” observed the co-lead author of the study Md Saad Bin-Alam, a uOttawa doctoral student in EECS.
“However, their attempts did not provide a significant improvement in the quality factors of the resonances of the arrays. We implemented a combination of techniques rather than a single approach and obtained an order-of-magnitude improvement demonstrating a metal nanoparticle array (metasurface) with a record-high quality factor.”
According to the researchers, structured surfaces – also called metasurfaces – have very promising prospects in a variety of nanophotonic applications that can never be explored using traditional natural bulk materials. Sensors, nanolasers, light beam shaping and steering are just a few examples of the many applications.
“Metasurfaces made of noble metal nanoparticles – gold or silver for instance – possess some unique benefits over non-metallic nanoparticles. They can confine and control light in a nanoscale volume that is less than one quarter of the wavelength of light (less than 100 nm, while the width of a hair is over 10 000 nm),” explained Md Saad Bin-Alam.
“Interestingly, unlike in non-metallic nanoparticles, the light is not confined or trapped inside the metal nanoparticles but is concentrated close to their surface. This phenomenon is scientifically called ‘localized surface plasmon resonances (LSPRs)’. This feature gives a great superiority to metal nanoparticles compared to their dielectric counterparts, because one could exploit such surface resonances to detect bio-organisms or molecules in medicine or chemistry. Also, such surface resonances could be used as the feedback mechanism necessary for laser gain. In such a way, one can realize a nanoscale tiny laser that can be adopted in many future nanophotonic applications, like light detection and ranging (LiDAR) for the far-field object detection.”
According to the researchers, the efficiency of these applications depends on the resonant Q-factors.
“Unfortunately, due to the high ‘absorptive’ and ‘radiative’ loss in metal nanoparticles, the LSPRs Q-factors are very low,” said co-lead author Dr. Orad Reshef, a postdoctoral fellow in the Department of Physics at the University of Ottawa.
“More than a decade ago, researchers found a way to mitigate the dissipative loss by carefully arranging the nanoparticles in a lattice. From such ‘surface lattice’ manipulation, a new ‘surface lattice resonance (SLR)’ emerges with suppressed losses. Until our work, the maximum Q-factors reported in SLRs was around a few hundred. Although such early reported SLRs were better than the low-Q LSPRs, they were still not very impressive for efficient applications. It led to the myth that metals are not useful for practical applications.”
A myth that the group was able to deconstruct during its work at the University of Ottawa’s Advanced Research Complex between 2017 and 2020.
“At first, we performed numerical modelling of a gold nanoparticle metasurface and were surprised to obtain quality factors of several thousand,” said Md Saad Bin-Alam, who primarily designed the metasurface structure.
“This value has never been reported experimentally, and we decided to analyze why and to attempt an experimental demonstration of such a high Q. We observed a very high-Q SLR of value nearly 2400, that is at least 10 times larger than the largest SLRs Q reported earlier.”
A discovery that made them realize that there’s still a lot to learn about metals.
“Our research proved that we are still far from knowing all the hidden mysteries of metal (plasmonic) nanostructures,” concluded Dr. Orad Reshef, who fabricated the metasurface sample. “Our work has debunked a decade-long myth that such structures are not suitable for real-life optical applications due to the high losses. We demonstrated that, by properly engineering the nanostructure and carefully conducting an experiment, one can improve the result significantly.”
Here’s a link to and a citation for the paper,
Ultra-high-Q resonances in plasmonic metasurfaces by M. Saad Bin-Alam, Orad Reshef, Yaryna Mamchur, M. Zahirul Alam, Graham Carlow, Jeremy Upham, Brian T. Sullivan, Jean-Michel Ménard, Mikko J. Huttunen, Robert W. Boyd & Ksenia Dolgaleva. Nature Communications volume 12, Article number: 974 (2021) DOI: https://doi.org/10.1038/s41467-021-21196-2 Published 12 February 2021
Caption: A comparison of how linear PEG (left) and cyclic PEG (right) attach to a gold nanoparticle Credit: Yubo Wang, Takuya Yamamoto
A January 20, 2021 news item on phys.org focuses on work designed to stop gold nanoparticles from clumping together (Note: A link has been removed),
Hokkaido University scientists have found a way to prevent gold nanoparticles from clumping, which could help towards their use as an anti-cancer therapy.
Attaching ring-shaped synthetic compounds to gold nanoparticles helps them retain their essential light-absorbing properties, Hokkaido University researchers report in the journal Nature Communications.
Metal nanoparticles have unique light-absorbing properties, making them interesting for a wide range of optical, electronic and biomedical applications. For example, if delivered to a tumour, they could react with applied light to kill cancerous tissue. A problem with this approach, though, is that they easily clump together in solution, losing their ability to absorb light. This clumping happens in response to a variety of factors, including temperature, salt concentration and acidity.
Scientists have been trying to find ways to ensure nanoparticles stay dispersed in their target environments. Covering them with polyethylene glycol, otherwise known as PEG, has been relatively successful at this in the case of gold nanoparticles. PEG is biocompatible and can prevent gold surfaces from clumping together in the laboratory and in living organisms, but improvements are still needed.
Applied chemist Takuya Yamamoto and colleagues at Hokkaido University, The University of Tokyo, and Tokyo Institute of Technology found that mixing gold nanoparticles with ring-shaped PEG, rather than the normally linear PEG, significantly improved dispersion. The ‘cyclic-PEG’ (c-PEG) attaches to the surfaces of the nanoparticles without forming chemical bonds with them, a process called physisorption. The coated nanoparticles remained dispersed when frozen, freeze-dried and heated.
The team tested the c-PEG-covered gold nanoparticles in mice and found that they cleared slowly from the blood and accumulated better in tumours compared to gold nanoparticles coated with linear PEG. However, accumulation was lower than desired levels, so the researchers recommend further investigations to fine-tune the nanoparticles for this purpose.
Associate Professor Takuya Yamamoto is part of the Laboratory of Chemistry of Molecular Assemblies at Hokkaido University, where he studies the properties and applications of various cyclic chemical compounds.
Here’s a link to and a citation for the paper,
Enhanced dispersion stability of gold nanoparticles by the physisorption of cyclic poly(ethylene glycol) by Yubo Wang, Jose Enrico Q. Quinsaat, Tomoko Ono, Masatoshi Maeki, Manabu Tokeshi, Takuya Isono, Kenji Tajima, Toshifumi Satoh, Shin-ichiro Sato, Yutaka Miura & Takuya Yamamoto. Nature Communications volume 11, Article number: 6089 (2020) DOI: https://doi.org/10.1038/s41467-020-19947-8 Published: 30 November 2020
A spiderweb-inspired fractal design is used for hemispherical 3D photodetection to replicate the vision system of arthropods. (Sena Huh image)
This image is pretty and I’m pretty sure it’s an illustration and not a real photodetection system. Regardless, an Oct. 21, 2020 news item on Nanowerk describes the research into producing a real 3D hemispheric photodetector for biomedical imaging (Note: A link has been removed),
Purdue University innovators are taking cues from nature to develop 3D photodetectors for biomedical imaging.
The researchers used some architectural features from spider webs to develop the technology. Spider webs typically provide excellent mechanical adaptability and damage-tolerance against various mechanical loads such as storms.
“We employed the unique fractal design of a spider web for the development of deformable and reliable electronics that can seamlessly interface with any 3D curvilinear surface,” said Chi Hwan Lee, a Purdue assistant professor of biomedical engineering and mechanical engineering. “For example, we demonstrated a hemispherical, or dome-shaped, photodetector array that can detect both direction and intensity of incident light at the same time, like the vision system of arthropods such as insects and crustaceans.”
The Purdue technology uses the structural architecture of a spider web that exhibits a repeating pattern. This work is published in Advanced Materials (“Fractal Web Design of a Hemispherical Photodetector Array with Organic-Dye-Sensitized Graphene Hybrid Composites”).
Lee said this provides unique capabilities to distribute externally induced stress throughout the threads according to the effective ratio of spiral and radial dimensions and provides greater extensibility to better dissipate force under stretching. Lee said it also can tolerate minor cuts of the threads while maintaining overall strength and function of the entire web architecture.
“The resulting 3D optoelectronic architectures are particularly attractive for photodetection systems that require a large field of view and wide-angle antireflection, which will be useful for many biomedical and military imaging purposes,” said Muhammad Ashraful Alam, the Jai N. Gupta Professor of Electrical and Computer Engineering.
Alam said the work establishes a platform technology that can integrate a fractal web design with system-level hemispherical electronics and sensors, thereby offering several excellent mechanical adaptability and damage-tolerance against various mechanical loads.
“The assembly technique presented in this work enables deploying 2D deformable electronics in 3D architectures, which may foreshadow new opportunities to better advance the field of 3D electronic and optoelectronic devices,” Lee said.
An October 26, 2020 news item on Nanowerk describes some new research that may lead the way to treatments for people with asbestos-related cancers (e.g., mesothelioma), Note: A link has been removed,
Gold nanotubes – tiny hollow cylinders one thousandth the width of a human hair – could be used to treat mesothelioma, a type of cancer caused by exposure to asbestos, according to a team of researchers at the Universities of Cambridge and Leeds.
In a study published in journal Small (“Exploring High Aspect Ratio Gold Nanotubes as Cytosolic Agents: Structural Engineering and Uptake into Mesothelioma Cells”), the researchers demonstrate that once inside the cancer cells, the nanotubes absorb light, causing them to heat up, thereby killing the cells.
…
Here`s an image illustrating the research,
Caption: Confocal fluorescence image of gold nanotures (green) in mesothelioma cells. Credit: Arsalan Azad
More than 2,600 people are diagnosed in the UK each year with mesothelioma, a malignant form of cancer caused by exposure to asbestos. Although the use of asbestos is outlawed in the UK now, the country has the world’s highest levels of mesothelioma because it imported vast amounts of asbestos in the post-war years. The global usage of asbestos remains high, particularly in low- and middle-income countries, which means mesothelioma will become a global problem.
“Mesothelioma is one of the ‘hard-to-treat’ cancers, and the best we can offer people with existing treatments is a few months of extra survival,” said Dr Arsalan Azad from the Cambridge Institute for Medical Research at the University of Cambridge. “There’s an important unmet need for new, effective treatments.”
In 2018, the University of Cambridge was awarded £10million from the Engineering and Physical Sciences Research Council to help develop engineering solutions, including nanotech, to find ways to address hard-to-treat cancers.
In a collaboration between the University of Cambridge and University of Leeds, researchers have developed a form of gold nanotubes whose physical properties are ‘tunable’ – in other words, the team can tailor the wall thickness, microstructure, composition, and ability to absorb particular wavelengths of light.
The researchers added the nanotubes to mesothelioma cells cultured in the lab and found that they were absorbed by the cells, residing close to the nucleus, where the cell’s DNA lies. When the team targeted the cells with a laser, the nanotubes absorbed the light and heated up, killing the mesothelioma cell.
Professor Stefan Marciniak, also from the Cambridge Institute for Medical Research, added: “The mesothelioma cells ‘eat’ the nanotubes, leaving them susceptible when we shine light on them. Laser light is able to penetrate deep into tissue without causing damage to surrounding tissue. It then gets absorbed by the nanotubes, which heat up and, we hope in the future, could be used to cause localised cancer-cell killing.”
The team will be developing the work further to ensure the nanotubes are targeted to cancer cells with less effect on normal tissue.
The nanotubes are made in a two-step process. First, solid silver nanorods are created of the desired diameter. Gold is then deposited from solution onto the surface of the silver. As the gold builds-up at the surface, the silver dissolves from the inside to leave a hollow nanotube.
The approach advanced by the Leeds team allows these nanotubes to be developed at room temperature, which should make their manufacture at scale more feasible.
Professor Stephen Evans from the School of Physics and Astronomy at the University of Leeds said: “Having control over the size and shape of the nanotubes allows us to tune them to absorb light where the tissue is transparent and will allow them to be used for both the imaging and treatment of cancers. The next stage will be to load these nanotubes with medicines for enhanced therapies.”
I’ve always been fond of ‘l’ words and so it is that I’m compelled to post a story about a “luciferin-luciferase system” or, in this case, a story about insect bioluminescence.
Caption: Researchers isolated molecules present in the larvae of the fungus gnat Orfelia fultoni Credit: Vadim Viviani, UFSCar
Molecules belonging to an almost unknown bioluminescent system found in larvae of the fungus gnat Orfelia fultoni (subfamily Keroplatinae) have been isolated for the first time by researchers at the Federal University of São Carlos (UFSCar) in the state of São Paulo, Brazil. The small fly is one of the few terrestrial organisms that produce blue light. It inhabits riverbanks in the Appalachian Mountains in the eastern United States. A key part of its bioluminescent system is a molecule also present in two recently discovered Brazilian flies.
The study, supported by Paulo Research Foundation – FAPESP, is published in Scientific Reports. Five authors are affiliated with UFSCar and two with universities in the United States.
The bioluminescent systems of glow-worms, fireflies and other insects are normally made up of luciferin (a low molecular weight molecule) and luciferase, an enzyme that catalyzes the oxidation of luciferin by oxygen, producing light. While some bioluminescent systems are well known and even used in biotechnological applications, others are poorly understood, including blue light-emitting systems, such as that of O. fultoni.
“In the published paper, we describe the properties of the insect’s luciferase and luciferin and their anatomical location in its larvae. We also specify several possible proteins that are possible candidates for the luciferase. We don’t yet know what type of protein it is, but it’s likely to be a hexamerin. In insects, hexamerins are storage proteins that provide amino acids, besides having other functions, such as binding low molecular weight compounds, like luciferin,” said Vadim Viviani, a professor in UFSCar’s Sustainability Science and Technology Center (CCTS) in Sorocaba, São Paulo, and principal investigator for the study.
The study was part of the FAPESP-funded project “Arthropod bioluminescence“. The partnership with United States-based researchers dates from a previous project, supported by FAPESP and the United States National Science Foundation (NSF), in partnership with Vanderbilt University (VU), located in Nashville, Tennessee.
In addition to luciferin and luciferase, researchers began characterizing a complex found in insects of the family Keroplatidae, which, in addition to O. fultoni, also includes a Brazilian species in the genus Neoditomyia that produces only luciferin and hence does not emit light.
Because they do not use it to emit light, the luciferin in O. fultoni and the Brazilian Neoditomyia has been named keroplatin. In larvae of this subfamily, keroplatin is associated with “black bodies” – large cells containing dark granules, proteins and probably mitochondria (energy-producing organelles). Researchers are still investigating the biological significance of this association between keroplatin and mitochondria.
“It’s a mystery,” Viviani said. “This luciferin may play a role in the mitochondrial energy metabolism. At night, probably in the presence of a natural chemical reducer, the luciferin is released by these black bodies and reacts with the surrounding luciferase to produce blue light. These are possibilities we plan to study.”
Brazilian cousins
An important factor in the elucidation of the United States insect’s bioluminescent system was the discovery of a larva that lives in Intervales State Park in São Paulo in 2018. It does not emit light but produces luciferin, similar to O. fultoni (read more at: agencia.fapesp.br/29066).
In their latest study, the group injected purified luciferase from the United States species into larvae of the Brazilian species, which then produced blue light. The nonluminescent Brazilian species is more abundant in nature than the United States species, so a larger amount of the material could be obtained for study purposes, especially to characterize the luciferin (keroplatin) present in both species.
In 2019, the group discovered and described Neoceroplatus betaryensis, a new species of fungus gnat, in collaboration with Cassius Stevani, a professor at the University of São Paulo’s Institute of Chemistry (IQ-USP). It was the first blue light-emitting insect found in South America and was detected in a privately held forest reserve near the Upper Ribeira State Tourist Park (PETAR) in the southern portion of the state of São Paulo. A close relative of O. fultoni, N. betaryensis inhabits fallen tree trunks in humid places (read more at: agencia.fapesp.br/31797).
“We show that the bioluminescent system of this Brazilian species is identical to that of O. fultoni. However, the insect is very rare, and so it’s hard to obtain sufficient material for research purposes,” Viviani said.
The researchers are now cloning the insect’s luciferase and characterizing it in molecular terms. They are also analyzing the chemical structure of its luciferin and the morphology of its lanterns.
“Once all this has been determined, we’ll be able to synthesize the luciferin and luciferase in the lab and use these systems in a range of biotech applications, such as studying cells. This will help us understand more about human diseases, among other things,” Viviani said.
Enhancing soap bubbles for your science explorations? It sounds like an entertaining activity you might give children for ‘painless’ science education. In this case, researchers at Technion – Israel Institute of Technology have made an exciting discovery, The following video is where I got the phrase “explorers of experimental science,”
A July 1, 2020 news item on Nanowerk announces the work (Note: A link has been removed),
A team of researchers from the Technion – Israel Institute of Technology has observed branched flow of light for the very first time. The findings are published in Nature and are featured on the cover of the July 2, 2020 issue (“Observation of branched flow of light”).
The study was carried out by Ph.D. student Anatoly (Tolik) Patsyk, in collaboration with Miguel A. Bandres, who was a postdoctoral fellow at Technion when the project started and is now an Assistant Professor at CREOL, College of Optics and Photonics, University of Central Florida. The research was led by Technion President Professor Uri Sivan and Distinguished Professor Mordechai (Moti) Segev of the Technion’s Physics and Electrical Engineering Faculties, the Solid State Institute, and the Russell Berrie Nanotechnology Institute.
When waves travel through landscapes that contain disturbances, they naturally scatter, often in all directions. Scattering of light is a natural phenomenon, found in many places in nature. For example, the scattering of light is the reason for the blue color of the sky. As it turns out, when the length over which disturbances vary is much larger than the wavelength, the wave scatters in an unusual fashion: it forms channels (branches) of enhanced intensity that continue to divide or branch out, as the wave propagates. This phenomenon is known as branched flow. It was first observed in 2001 in electrons and had been suggested to be ubiquitous and occur also for all waves in nature, for example – sound waves and even ocean waves. Now, Technion researchers are bringing branched flow to the domain of light: they have made an experimental observation of the branched flow of light.
“We always had the intention of finding something new, and we were eager to find it. It was not what we started looking for, but we kept looking and we found something far better,” says Asst. Prof. Miguel Bandres. “We are familiar with the fact that waves spread when they propagate in a homogeneous medium. But for other kinds of mediums, waves can behave in very different ways. When we have a disordered medium where the variations are not random but smooth, like a landscape of mountains and valleys, the waves will propagate in a peculiar way. They will form channels that keep dividing as the wave propagates, forming a beautiful pattern resembling the branches of a tree.”
In their research, the team coupled a laser beam to a soap membrane, which contains random variations in membrane thickness. They discovered that when light propagates within the soap film, rather than being scattered, the light forms elongated branches, creating the branched flow phenomenon for light.
“In optics we usually work hard to make light stay focused and propagate as a collimated beam, but here the surprise is that the random structure of the soap film naturally caused the light to stay focused. It is another one of nature’s surprises,” says Tolik Patsyk.
The ability to create branched flow in the field of optics offers new and exciting opportunities for investigating and understanding this universal wave phenomenon.
“There is nothing more exciting than discovering something new and this is the first demonstration of this phenomenon with light waves,” says Technion President Prof. Uri Sivan. “This goes to show that intriguing phenomena can also be observed in simple systems and one just has to be perceptive enough to uncover them. As such, bringing together and combining the views of researchers from different backgrounds and disciplines has led to some truly interesting insights.”
“The fact that we observe it with light waves opens remarkable new possibilities for research, starting with the fact that we can characterize the medium in which light propagates to very high precision and the fact that we can also follow those branches accurately and study their properties,” he adds.
Distinguished Prof. Moti Segev looks to the future. “I always educate my team to think beyond the horizon,” he says, “to think about something new, and at the same time – look at the experimental facts as they are, rather than try to adapt the experiments to meet some expected behavior. Here, Tolik was trying to measure something completely different and was surprised to see these light branches which he could not initially explain. He asked Miguel to join in the experiments, and together they upgraded the experiments considerably – to the level they could isolate the physics involved. That is when we started to understand what we see. It took more than a year until we understood that what we have is the strange phenomenon of “branched flow”, which at the time was never considered in the context of light waves. Now, with this observation – we can think of a plethora of new ideas. For example, using these light branches to control the fluidic flow in liquid, or to combine the soap with fluorescent material and cause the branches to become little lasers. Or to use the soap membranes as a platform for exploring fundamentals of waves, such as the transitions from ordinary scattering which is always diffusive, to branched flow, and subsequently to Anderson localization. There are many ways to continue this pioneering study. As we did many times in the past, we would like to boldly go where no one has gone before.”
The project is now continuing in the laboratories of Profs. Segev and Sivan at Technion, and in parallel in the newly established lab of Prof. Miguel Bandres at UCF.
Here’s a link to and a citation for the paper,
Observation of branched flow of light by Anatoly Patsyk, Uri Sivan, Mordechai Segev & Miguel A. Bandres Nature volume 583, pages60–65 (2020) DOI: https://doi.org/10.1038/s41586-020-2376-8 Published: 01 July 2020 Issue Date: 02 July 2020
This is one of three pieces by Rita Letendre that underwent chemical mapping according to an August 5, 2020 CLS news release by Victoria Martinez (also received via email),
Research undertaken at the Canadian Light Source (CLS) at the University of Saskatchewan was key to understanding how to conserve experimental oil paintings by Rita Letendre, one of Canada’s most respected living abstract artists.
The work done at the CLS was part of a collaborative research project between the Art Gallery of Ontario (AGO) and the Canadian Conservation Institute (CCI) that came out of a recent retrospective Rita Letendre: Fire & Light at the AGO. During close examination, Meaghan Monaghan, paintings conservator from the Michael and Sonja Koerner Centre for Conservation, observed that several of Letendre’s oil paintings from the fifties and sixties had suffered significant degradation, most prominently, uneven gloss and patchiness, snowy crystalline structures coating the surface known as efflorescence, and cracking and lifting of the paint in several areas.
Kate Helwig, Senior Conservation Scientist at the Canadian Conservation Institute, says these problems are typical of mid-20th century oil paintings. “We focused on three of Rita Letendre’s paintings in the AGO collection, which made for a really nice case study of her work and also fits into the larger question of why oil paintings from that period tend to have degradation issues.”
Growing evidence indicates that paintings from this period have experienced these problems due to the combination of the experimental techniques many artists employed and the additives paint manufacturers had begun to use.
In order to determine more precisely how these factors affected Letendre’s paintings, the research team members applied a variety of analytical techniques, using microscopic samples taken from key points in the works.
“The work done at the CLS was particularly important because it allowed us to map the distribution of materials throughout a paint layer such as an impasto stroke,” Helwig said. The team used Mid-IR chemical mapping at the facility, which provides a map of different molecules in a small sample.
For example, chemical mapping at the CLS allowed the team to understand the distribution of the paint additive aluminum stearate throughout the paint layers of the painting Méduse. This painting showed areas of soft, incompletely dried paint, likely due to the high concentration and incomplete mixing of this additive.
The painting Victoire had a crumbling base paint layer in some areas and cracking and efflorescence at the surface in others. Infrared mapping at the CLS allowed the team to determine that excess free fatty acids in the paint were linked to both problems; where the fatty acids were found at the base they formed zing “soaps” which led to crumbling and cracking, and where they had moved to the surface they had crystallized, causing the snowflake-like efflorescence.
AGO curators and conservators interviewed Letendre to determine what was important to her in preserving and conserving her works, and she highlighted how important an even gloss across the surface was to her artworks, and the philosophical importance of the colour black in her paintings. These priorities guided conservation efforts, while the insights gained through scientific research will help maintain the works in the long term.
In order to restore the black paint to its intended even finish for display, conservator Meaghan Monaghan removed the white crystallization from the surface of Victoire, but it is possible that it could begin to recur. Understanding the processes that lead to this degradation will be an important tool to keep Letendre’s works in good condition.
“The world of modern paint research is complicated; each painting is unique, which is why it’s important to combine theoretical work on model paint systems with this kind of case study on actual works of art” said Helwig. The team hopes to collaborate on studying a larger cross section of Letendre’s paintings in oil and acrylic in the future to add to the body of knowledge.
The latest news from the CSPC 2020 (November 16 – 20 with preconference events from Nov. 1 -14) organizers is that registration is open and early birds have a deadline of September 27, 2020 (from an August 6, 2020 CSPC 2020 announcement received via email),
It’s time! Registration for the 12th Canadian Science Policy Conference (CSPC 2020) is open now. Early Bird registration is valid until Sept. 27th [2020].
CSPC 2020 is coming to your offices and homes:
Register for full access to 3 weeks of programming of the biggest science and innovation policy forum of 2020 under the overarching theme: New Decade, New Realities: Hindsight, Insight, Foresight.
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The virtual conference features an exclusive array of offerings:
3D Lounge and Exhibit area
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Many more
Don’t miss this unique opportunity to engage in the most important discussions of science and innovation policy with insights from around the globe, just from your office, home desk, or your mobile phone.
Benefit from significantly reduced registration fees for an online conference with an option for discount for multiple ticket purchases
The preliminary programme can be found here. This year there will be some discussion of a Canadian synthetic biology roadmap, presentations on various Indigenous concerns (mostly health), a climate challenge presentation focusing on Mexico and social vulnerability and another on parallels between climate challenges and COVID-19. There are many presentations focused on COVID-19 and.or health.
International Symposium on Electronic Arts (ISEA) 2020
According to my latest information, the early bird rate for ISEA 2020 (Oct. 13 -18) ends on August 13, 2020. (My June 22, 2020 posting describes their plans for the online event.)
Margaux Davoine has written up a teaser for the 2020 edition of ISEA in the form of an August 6, 2020 interview with Yan Breuleux. I’ve excerpted one bit,
Finally, thinking about this year’s theme [Why Sentience?], there might be something a bit ironic about exploring the notion of sentience (historically reserved for biological life, and quite a small subsection of it) through digital media and electronic arts. There’s been much work done in the past 25 years to loosen the boundaries between such distinctions: how do you imagine ISEA2020 helping in that?
The similarities shared between humans, animals, and machines are fundamental in cybernetic sciences. According to the founder of cybernetics Norbert Wiener, the main tenets of the information paradigm – the notion of feedback – can be applied to humans, animals as well as the material world. Famously, the AA predictor (as analysed by Peter Galison in 1994) can be read as a first attempt at human-machine fusion (otherwise known as a cyborg).
The infamous Turing test also tends to blur the lines between humans and machines, between language and informational systems. Second-order cybernetics are often associated with biologists Francisco Varela and Humberto Maturana. The very notion of autopoiesis (a system capable of maintaining a certain level of stability in an unstable environment) relates back to the concept of homeostasis formulated by Willam Ross [William Ross Ashby] in 1952. Moreover, the concept of “ecosystems” emanates directly from the field of second-order cybernetics, providing researchers with a clearer picture of the interdependencies between living and non-living organisms. In light of these theories, the absence of boundaries between animals, humans, and machines constitutes the foundation of the technosciences paradigm. New media, technological arts, virtual arts, etc., partake in the dialogue between humans and machines, and thus contribute to the prolongation of this paradigm. Frank Popper nearly called his book “Techno Art” instead of “Virtual Art”, in reference to technosciences (his editor suggested the name change). For artists in the technological arts community, Jakob von Uexkull’s notion of “human-animal milieu” is an essential reference. Also present in Simondon’s reflections on human environments (both natural and artificial), the notion of “milieu” is quite important in the discourses about art and the environment. Concordia University’s artistic community chose the concept of “milieu” as the rallying point of its research laboratories.
ISEA2020’s theme resonates particularly well with the recent eruption of processing and artificial intelligence technologies. For me, Sentience is a purely human and animal idea: machines can only simulate our ways of thinking and feeling. Partly in an effort to explore the illusion of sentience in computers, Louis-Philippe Rondeau, Benoît Melançon and I have established the Mimesis laboratory at NAD University. Processing and AI technologies are especially useful in the creation of “digital doubles”, “Vactors”, real-time avatar generation, Deep Fakes and new forms of personalised interactions.
I adhere to the epistemological position that the living world is immeasurable. Through their ability to simulate, machines can merely reduce complex logics to a point of understandability. The utopian notion of empathetic computers is an idea mostly explored by popular science-fiction movies. Nonetheless, research into computer sentience allows us to devise possible applications, explore notions of embodiment and agency, and thereby develop new forms of interaction. Beyond my own point of view, the idea that machines can somehow feel emotions gives artists and researchers the opportunity to experiment with certain findings from the fields of the cognitive sciences, computer sciences and interactive design. For example, in 2002 I was particularly marked by an immersive installation at Universal Exhibition in Neuchatel, Switzerland titled Ada: Intelligence Space. The installation comprised an artificial environment controlled by a computer, which interacted with the audience on the basis of artificial emotion. The system encouraged visitors to participate by intelligently analysing their movements and sounds. Another example, Louis-Philippe Demers’ Blind Robot (2012), demonstrates how artists can be both critical of, and amazed by, these new forms of knowledge. Additionally, the 2016 BIAN (Biennale internationale d’art numérique), organized by ELEKTRA (Alain Thibault) explored the various ways these concepts were appropriated in installation and interactive art. The way I see it, current works of digital art operate as boundary objects. The varied usages and interpretations of a particular work of art allow it to be analyzed from nearly every angle or field of study. Thus, philosophers can ask themselves: how does a computer come to understand what being human really is?
I have yet to attend conferences or exchange with researchers on that subject. Although the sheer number of presentation propositions sent to ISEA2020, I have no doubt that the symposium will be the ideal context to reflect on the concept of Sentience and many issues raised therein.
For the last bit of news.
HotPopRobot, one of six global winners of 2020 NASA SpaceApps COVID-19 challenge
I last wrote about HotPopRobot’s (Artash and Arushi with a little support from their parents) response to the 2020 NASA (US National Aeronautics and Space Administration) SpaceApps challenge in my July 1, 2020 post, Toronto COVID-19 Lockdown Musical: a data sonification project from HotPopRobot. (You’ll find a video of the project embedded in the post.)
We are excited to become the global winners of the 2020 NASA SpaceApps COVID-19 Challenge from among 2,000 teams from 150 countries. The six Global Winners will be invited to visit a NASA Rocket Launch site to view a spacecraft launch along with the SpaceApps Organizing team once travel is deemed safe. They will also receive an invitation to present their projects to NASA, ESA [European Space Agency], JAXA [Japan Aerospace Exploration Agency], CNES [Centre National D’Etudes Spatiales; France], and CSA [Canadian Space Agency] personnel. https://covid19.spaceappschallenge.org/awards
15,000 participants joined together to submit over 1400 projects for the COVID-19 Global Challenge that was held on 30-31 May 2020. 40 teams made to the Global Finalists. Amongst them, 6 teams became the global winners!
The 2020 SpaceApps was an international collaboration between NASA, Canadian Space Agency, ESA, JAXA, CSA,[sic] and CNES focused on solving global challenges. During a period of 48 hours, participants from around the world were required to create virtual teams and solve any of the 12 challenges related to the COVID-19 pandemic posted on the SpaceApps website. More details about the 2020 SpaceApps COVID-19 Challenge: https://sa-2019.s3.amazonaws.com/media/documents/Space_Apps_FAQ_COVID_.pdf
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We have been participating in NASA Space Challenge for the last seven years since 2014. We were only 8 years and 5 years respectively when we participated in our very first SpaceApps 2014.
We have grown up learning more about space, tacking global challenges, making hardware and software projects, participating in meetings, networking with mentors and teams across the globe, and giving presentations through the annual NASA Space Apps Challenges. This is one challenge we look forward to every year.
It has been a fun and exciting journey meeting so many people and astronauts and visiting several fascinating places on the way! We hope more kids, youths, and families are inspired by our space journey. Space is for all and is yours to discover!
Both of these news bits are concerned with light for one reason or another.
Rice University (Texas, US) and breaking fluorocarbon bonds
The secret to breaking fluorocarbon bonds is light according to a June 22, 2020 news item on Nanowerk,
Rice University engineers have created a light-powered catalyst that can break the strong chemical bonds in fluorocarbons, a group of synthetic materials that includes persistent environmental pollutants.
In a study published this month in Nature Catalysis, Rice nanophotonics pioneer Naomi Halas and collaborators at the University of California, Santa Barbara (UCSB) and Princeton University showed that tiny spheres of aluminum dotted with specks of palladium could break carbon-fluorine (C-F) bonds via a catalytic process known as hydrodefluorination in which a fluorine atom is replaced by an atom of hydrogen.
The strength and stability of C-F bonds are behind some of the 20th century’s most recognizable chemical brands, including Teflon, Freon and Scotchgard. But the strength of those bonds can be problematic when fluorocarbons get into the air, soil and water. Chlorofluorocarbons, or CFCs, for example, were banned by international treaty in the 1980s after they were found to be destroying Earth’s protective ozone layer, and other fluorocarbons were on the list of “forever chemicals” targeted by a 2001 treaty.
“The hardest part about remediating any of the fluorine-containing compounds is breaking the C-F bond; it requires a lot of energy,” said Halas, an engineer and chemist whose Laboratory for Nanophotonics (LANP) specializes in creating and studying nanoparticles that interact with light.
Over the past five years, Halas and colleagues have pioneered methods for making “antenna-reactor” catalysts that spur or speed up chemical reactions. While catalysts are widely used in industry, they are typically used in energy-intensive processes that require high temperature, high pressure or both. For example, a mesh of catalytic material is inserted into a high-pressure vessel at a chemical plant, and natural gas or another fossil fuel is burned to heat the gas or liquid that’s flowed through the mesh. LANP’s antenna-reactors dramatically improve energy efficiency by capturing light energy and inserting it directly at the point of the catalytic reaction.
In the Nature Catalysis study, the energy-capturing antenna is an aluminum particle smaller than a living cell, and the reactors are islands of palladium scattered across the aluminum surface. The energy-saving feature of antenna-reactor catalysts is perhaps best illustrated by another of Halas’ previous successes: solar steam. In 2012, her team showed its energy-harvesting particles could instantly vaporize water molecules near their surface, meaning Halas and colleagues could make steam without boiling water. To drive home the point, they showed they could make steam from ice-cold water.
The antenna-reactor catalyst design allows Halas’ team to mix and match metals that are best suited for capturing light and catalyzing reactions in a particular context. The work is part of the green chemistry movement toward cleaner, more efficient chemical processes, and LANP has previously demonstrated catalysts for producing ethylene and syngas and for splitting ammonia to produce hydrogen fuel.
Study lead author Hossein Robatjazi, a Beckman Postdoctoral Fellow at UCSB who earned his Ph.D. from Rice in 2019, conducted the bulk of the research during his graduate studies in Halas’ lab. He said the project also shows the importance of interdisciplinary collaboration.
“I finished the experiments last year, but our experimental results had some interesting features, changes to the reaction kinetics under illumination, that raised an important but interesting question: What role does light play to promote the C-F breaking chemistry?” he said.
The answers came after Robatjazi arrived for his postdoctoral experience at UCSB. He was tasked with developing a microkinetics model, and a combination of insights from the model and from theoretical calculations performed by collaborators at Princeton helped explain the puzzling results.
“With this model, we used the perspective from surface science in traditional catalysis to uniquely link the experimental results to changes to the reaction pathway and reactivity under the light,” he said.
The demonstration experiments on fluoromethane could be just the beginning for the C-F breaking catalyst.
“This general reaction may be useful for remediating many other types of fluorinated molecules,” Halas said.
Caption: An artist’s illustration of the light-activated antenna-reactor catalyst Rice University engineers designed to break carbon-fluorine bonds in fluorocarbons. The aluminum portion of the particle (white and pink) captures energy from light (green), activating islands of palladium catalysts (red). In the inset, fluoromethane molecules (top) comprised of one carbon atom (black), three hydrogen atoms (grey) and one fluorine atom (light blue) react with deuterium (yellow) molecules near the palladium surface (black), cleaving the carbon-fluorine bond to produce deuterium fluoride (right) and monodeuterated methane (bottom). Credit: H. Robatjazi/Rice University
Called “robotic soft matter by the Northwestern team,” the materials move without complex hardware, hydraulics or electricity. The researchers believe the lifelike materials could carry out many tasks, with potential applications in energy, environmental remediation and advanced medicine.
“We live in an era in which increasingly smarter devices are constantly being developed to help us manage our everyday lives,” said Northwestern’s Samuel I. Stupp, who led the experimental studies. “The next frontier is in the development of new science that will bring inert materials to life for our benefit — by designing them to acquire capabilities of living creatures.”
The research will be published on June 22 [2020] in the journal Nature Materials.
Stupp is the Board of Trustees Professor of Materials Science and Engineering, Chemistry, Medicine and Biomedical Engineering at Northwestern and director of the Simpson Querrey Institute He has appointments in the McCormick School of Engineering, Weinberg College of Arts and Sciences and Feinberg School of Medicine. George Schatz, the Charles E. and Emma H. Morrison Professor of Chemistry in Weinberg, led computer simulations of the materials’ lifelike behaviors. Postdoctoral fellow Chuang Li and graduate student Aysenur Iscen, from the Stupp and Schatz laboratories, respectively, are co-first authors of the paper.
Although the moving material seems miraculous, sophisticated science is at play. Its structure comprises nanoscale peptide assemblies that drain water molecules out of the material. An expert in materials chemistry, Stupp linked the peptide arrays to polymer networks designed to be chemically responsive to blue light.
When light hits the material, the network chemically shifts from hydrophilic (attracts water) to hydrophobic (resists water). As the material expels the water through its peptide “pipes,” it contracts — and comes to life. When the light is turned off, water re-enters the material, which expands as it reverts to a hydrophilic structure.
This is reminiscent of the reversible contraction of muscles, which inspired Stupp and his team to design the new materials.
“From biological systems, we learned that the magic of muscles is based on the connection between assemblies of small proteins and giant protein polymers that expand and contract,” Stupp said. “Muscles do this using a chemical fuel rather than light to generate mechanical energy.”
For Northwestern’s bio-inspired material, localized light can trigger directional motion. In other words, bending can occur in different directions, depending on where the light is located. And changing the direction of the light also can force the object to turn as it crawls on a surface.
Stupp and his team believe there are endless possible applications for this new family of materials. With the ability to be designed in different shapes, the materials could play a role in a variety of tasks, ranging from environmental clean-up to brain surgery.
“These materials could augment the function of soft robots needed to pick up fragile objects and then release them in a precise location,” he said. “In medicine, for example, soft materials with ‘living’ characteristics could bend or change shape to retrieve blood clots in the brain after a stroke. They also could swim to clean water supplies and sea water or even undertake healing tasks to repair defects in batteries, membranes and chemical reactors.”
Fascinating, eh? No batteries, no power source, just light to power movement. For the curious, here’s a link to and a citation for the paper,
Supramolecular–covalent hybrid polymers for light-activated mechanical actuation by Chuang Li, Aysenur Iscen, Hiroaki Sai, Kohei Sato, Nicholas A. Sather, Stacey M. Chin, Zaida Álvarez, Liam C. Palmer, George C. Schatz & Samuel I. Stupp. Nature Materials (2020) DOI: https://doi.org/10.1038/s41563-020-0707-7 Published: 22 June 2020
I’ve bookended information about the talk with physicist Katie Mack at Canada’s Perimeter Institute on May 6, 2020 with two items on visual art and mathematics and the sciences.
Mathematical sculpting
Robert Fathauer’s Three-Fold Hyperbolic Form exhibits negative curvature, a concept in geometry and topology that describes a surface curving in two directions at every point. Hemp crochet by Marla Peterson. Image courtesy of Robert Fathauer. [downloaded from https://www.pnas.org/content/114/26/6643.full]
You’ll find this image and a few more in a fascinating 2017 paper (see link and citation below) about mathematical sculpture,
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Ferguson [Helaman Ferguson], who holds a doctorate in mathematics, never chose between art and science: now nearly 77 years old, he’s a mathematical sculptor. Working in stone and bronze, Ferguson creates sculptures, often placed on college campuses, that turn deep mathematical ideas into solid objects that anyone—seasoned professors, curious children, wayward mathophobes—can experience for themselves.
Mathematics has an intrinsic aesthetic—proofs are often described as “beautiful” or “elegant”—that can be difficult for mathematicians to communicate to outsiders, says Ferguson. “It isn’t something you can tell somebody about on the street,” he says. “But if I hand them a sculpture, they’re immediately relating to it.” Sculpture, he says, can tell a story about math in an accessible language.
Live webcast: theoretical cosmologist & science communicator Katie Mack
The live webcast will take place at 4 pm PT (1600 hours) on Wednesday, May 6, 2020. Here’s more about Katie Mack and the webcast from the event webpage (click through to the event page to get to the webcast) on the Perimeter Institute of Theoretical Physics (PI) website,
In a special live webcast on May 6 [2020] at 7 pm ET [4 pm PT], theoretical cosmologist and science communicator Katie Mack — known to her many Twitter followers as @astrokatie — will answer questions about her favourite subject: the end of the universe.
Mack, who holds a Simons Emmy Noether Visiting Fellowship at Perimeter, will give viewers a sneak peek at her upcoming book, The End of Everything (Astrophysically Speaking). She will then participate in a live “ask me anything” session, answering questions submitted via social media using the hashtag #piLIVE.
Mack is an Assistant Professor at North Carolina State University whose research investigates dark matter, vacuum decay, and the epoch of reionization. Mack is a popular science communicator on social media, and has contributed to Scientific American, Slate, Sky & Telescope, Time, and Cosmos.
Uniting quantum theory with Einstein’s Theory of General Relativity with a drawing about light
The article by Stephon Alexander was originally published March 16, 2017 for Nautilus. My excerpts are from a getpocket.com selection,
LIGHT IN THE GARDEN: This drawing by the Oakes brothers, Irwin Gardens at the Getty in Winter, inspired the author to think anew about quantum mechanics and general relativity. The meticulous drawing, done on curved paper, allows viewers to reflect on the act of perception. Credit: Ryan and Trevor Oakes [downloaded from http://nautil.us/issue/46/balance/what-this-drawing-taught-me-about-four_dimensional-spacetime]
My aim as a theoretical physicist is to unite quantum theory with Einstein’s Theory of General Relativity. While there are a few proposals for this unification, such as string theory and loop quantum gravity, many roadblocks to a complete unification remain.
Einstein’s theory tells us the gravitational force is a direct manifestation of space and time bending. The sun bends the fabric of space, much like a sleeping person bends a mattress. Planetary orbits, including Earth’s, are motion along the contours of the bent space created by the sun. This theory provides some critical insights into the nature of light.
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… one summer, I had the most unexpected breakthrough. Beth Jacobs, a member of the New York Academy of Sciences’ Board of Governors, invited me and some friends to her New York City apartment to meet the Oakes twins, artists who have gained attention in recent years for their drawings as well as the innovative technique and inventions they deploy to create them. An Oakes work, Irwin Gardens at the Getty in Winter (2011), an intricate drawing of the famous gardens designed by Robert Irwin at The Getty Museum in Los Angeles, was displayed on the balcony of Jacobs’ apartment overlooking Central Park, with the backdrop of the New York City skyline lit with a warm orange sky moments before sunset.
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As I gazed at the drawing, I could feel the artists challenging me to reconsider the nature of light. I began to realize I should consider not only the physics of light, but also how light information is perceived by observers, when theorizing and conceiving new principles to unify quantum mechanics and general relativity. …
Ryan and Trevor Oakes, 35, have been exploring the impact and intersection of visual perception and the physics of light since they were kids. After attending The Cooper Union for the Advancement of Science and Art in New York City, and years of experimentation and inventing new techniques, the twins exploited the notion that light information is better described when originating from a spherical surface.
