Category Archives: nanotechnology

Students from Nakoda Oyade Education Centre and scientists at the Canadian Light Source (CLS) use science to help bison

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It’s known as Paskwâwimostos – ᐸᐢᑳᐧᐃᐧᒧᐢᑐᐢ – The Bison Project and is being conducted at Canada’s only synchrotron, the Canadian Light Source (CLS) in Saskatoon, Saskatchewan. Here’s more from a November 24, 2022 CLS news release (also received via email), Note: Links have been removed,

Bison have long held a prominent place in the culture of the Carry the Kettle Nakoda Nation, located about 100 kms east of Regina. The once-abundant animals were a vital source of food and furs for the ancestors of today’s Carry the Kettle people.

Now, high school students from Nakoda Oyade Education Centre at Carry the Kettle are using synchrotron imaging to study the health of a local bison herd, with an eye to protecting and growing their numbers.

Armin Eashappie, a student involved in the Bison Project, says the work she and her classmates are doing is a chance to give back to an animal that was once integral to the very existence of her community. “We don’t want them to go extinct, says Eashappie. “They helped us with everything. We got our tools, our clothes, our food from them. We used every single part of the buffalo, nothing was left behind…they
even helped us make our homes – the teepees – we used the hides to cover them up.”

Eashappie’s classmate, Leslie Kaysaywaysemat, says that if their team can identify items the bison are eating that are not good for their health, these could potentially be replaced by other, healthier items. “We want to preserve them and make sure all generations can see how magnificent these creatures are,” he says.

The students, who are participating in the CLS’s Bison Project, gathered samples of bison hair, soil from where the animals graze, and plants they feed on, then analyzed them using the IDEAS beamline at the CLS. The Bison Project, coordinated by the Education group of the CLS, integrates Traditional Knowledge and mainstream science in a transformative research experience for First Nation, Métis, and Inuit
students.

Timothy Eashappie, Elder for the Bison Project, says it’s “awesome” that the students can use the Canadian Light Source machine to learn more about an animal that his people have long taken care of on the prairies. “That’s how we define ourselves – as
Buffalo People,” says Eashappie. “Since the beginning of time, they gave themselves to us, and now these young people are finding out how important these buffalo are to them, because it preserves their language, their culture, and their way of life. And now it’s our turn to take care of the bison.”

Once they’ve completed their analysis, the students will share their findings with the Chief and Council for Carry the Kettle.

…

The Canadian Light Source (CLS) is a national research facility of the University of Saskatchewan and one of the largest science projects in Canada’s history. More than 1,000 academic, government and industry scientists from around the world use the CLS every year in innovative health, agriculture, environment, and advanced materials research.

The Canada Foundation for Innovation [CFI], Natural Sciences and Engineering Research Council [NSERC], Canadian Institutes of Health Research [CIHR], the Government of Saskatchewan, and the University of Saskatchewan fund CLS operations.

You can find more about the CLS Bison Project here,

The Bison Project integrates Traditional Knowledge (TK) and mainstream Science in an experience that engages First Nation, Métis, and Inuit (FNMI) teachers, students, and communities. The Bison Project creates a unique opportunity to incorporate land-based hunting and herd management, synchrotron science, mainstream science principles and TK.

…

I found a bit more information about bison and their return in a November 23, 2020 article by Mark A. Bonta for The Daylighter,

For ecologists and environmentalists, it’s more than just a story about the return of a keystone species. 

The bison, it turns out, is an animal that maintains and restores the prairie.

Ecological restoration

Unlike cattle, bison are wallowers, so these powerful animals’ efforts to rid themselves of insect parasites, by rubbing their hide and rolling around on the ground, actually create permanent depressions, called bison wallows, in the landscape. 

These create fertile ground for diverse plant species — and the animals that rely on them. 

Bison also rub against woody plants and kill them off, keeping the prairies open, while their dung fertilizes the soil.

Iconic species like the greater prairie-chicken and the prairie dog all benefit from the restoration of bison. 

Bison herds have also proved highly adaptive to the “new,” post-colonial ecology of the Great Plains.

They are adapting to hunting season, for example, by delaying their migration. This keeps them out of harm’s way — but also increases the risk of human-bison conflicts.

Bonta’s article provides a little more detail about the mixed feelings that the return of the bison have engendered.

Transforming bacterial cells into living computers

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If this were a movie instead of a press release, we’d have some ominous music playing over a scene in a pristine white lab. Instead, we have a November 13, 2022 Technion-Israel Institute of Technology press release (also on EurekAlert) where the writer tries to highlight the achievement while downplaying the sort of research (in synthetic biology) that could have people running for the exits,

Bringing together concepts from electrical engineering and bioengineering tools, Technion and MIT [Massachusetts Institute of Technology] scientists collaborated to produce cells engineered to compute sophisticated functions – “biocomputers” of sorts. Graduate students and researchers from Technion – Israel Institute of Technology Professor Ramez Daniel’s Laboratory for Synthetic Biology & Bioelectronics worked together with Professor Ron Weiss from the Massachusetts Institute of Technology to create genetic “devices” designed to perform computations like artificial neural circuits. Their results were recently published in Nature Communications.

The genetic material was inserted into the bacterial cell in the form of a plasmid: a relatively short DNA molecule that remains separate from the bacteria’s “natural” genome. Plasmids also exist in nature, and serve various functions. The research group designed the plasmid’s genetic sequence to function as a simple computer, or more specifically, a simple artificial neural network. This was done by means of several genes on the plasmid regulating each other’s activation and deactivation according to outside stimuli.

What does it mean that a cell is a circuit? How can a computer be biological?

At its most basic level, a computer consists of 0s and 1s, of switches. Operations are performed on these switches: summing them, picking the maximal or minimal value between them, etc. More advanced operations rely on the basic ones, allowing a computer to play chess or fly a rocket to the moon.

In the electronic computers we know, the 0/1 switches take the form of transistors. But our cells are also computers, of a different sort. There, the presence or absence of a molecule can act as a switch. Genes activate, trigger or suppress other genes, forming, modifying, or removing molecules. Synthetic biology aims (among other goals) to harness these processes, to synthesize the switches and program the genes that would make a bacterial cell perform complex tasks. Cells are naturally equipped to sense chemicals and to produce organic molecules. Being able to “computerize” these processes within the cell could have major implications for biomanufacturing and have multiple medical applications.

The Ph.D students (now doctors) Luna Rizik and Loai Danial, together with Dr. Mouna Habib, under the guidance of Prof. Ramez Daniel from the Faculty of Biomedical Engineering at the Technion, and in collaboration with Prof. Ron Weiss from the Synthetic Biology Center, MIT,  were inspired by how artificial neural networks function. They created synthetic computation circuits by combining existing genetic “parts,” or engineered genes, in novel ways, and implemented concepts from neuromorphic electronics into bacterial cells. The result was the creation of bacterial cells that can be trained using artificial intelligence algorithms.

The group were able to create flexible bacterial cells that can be dynamically reprogrammed to switch between reporting whether at least one of a test chemicals, or two, are present (that is, the cells were able to switch between performing the OR and the AND functions). Cells that can change their programming dynamically are capable of performing different operations under different conditions. (Indeed, our cells do this naturally.) Being able to create and control this process paves the way for more complex programming, making the engineered cells suitable for more advanced tasks. Artificial Intelligence algorithms allowed the scientists to produce the required genetic modifications to the bacterial cells at a significantly reduced time and cost.

Going further, the group made use of another natural property of living cells: they are capable of responding to gradients. Using artificial intelligence algorithms, the group succeeded in harnessing this natural ability to make an analog-to-digital converter – a cell capable of reporting whether the concentration of a particular molecule is “low”, “medium”, or “high.” Such a sensor could be used to deliver the correct dosage of medicaments, including cancer immunotherapy and diabetes drugs.

Of the researchers working on this study, Dr. Luna Rizik and Dr. Mouna Habib hail from the Department of Biomedical Engineering, while Dr. Loai Danial is from the Andrew and Erna Viterbi Faculty of Electrical Engineering. It is bringing the two fields together that allowed the group to make the progress they did in the field of synthetic biology.

This work was partially funded by the Neubauer Family Foundation, the Israel Science Foundation (ISF), European Union’s Horizon 2020 Research and Innovation Programme, the Technion’s Lorry I. Lokey interdisciplinary Center for Life Sciences and Engineering, and the [US Department of Defense] Defense Advanced Research Projects Agency [DARPA].

Here’s a link to and a citation for the paper,

Synthetic neuromorphic computing in living cells by Luna Rizik, Loai Danial, Mouna Habib, Ron Weiss & Ramez Daniel. Nature Communications volume 13, Article number: 5602 (2022) DOIL https://doi.org/10.1038/s41467-022-33288-8 Published: 24 September 2022

This paper is open access.

Teeny adventures, Latent Life, and photonic writing—a March 28, 2023 talk at 1 pm PT at the University of British Columbia

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After reading the latest newsletter (received via email on March 20, 2023), featuring Scott Billings’ talk ‘Latest Life’, from the University of British Columbia’s (UBC) Belkin Gallery I was reminded of a book produced at the nanoscale back in 2009 (May 21, 2009 posting; scroll down to the final paragraph) and which I wrote about again in 2012 (October 12, 2012 posting) when ‘Teeny Ted from Turnip Town’ was added to the Guinness Book of Records as the world’s smallest book. (‘Teeny Ted’ also has a Wikipedia entry.)

The March 20, 2023 Belkin Gallery (also known as the Morris and Helen Belkin Art Gallery) newsletter is promoting the next Ars Scientia events (the information can also be found on this webpage),

We hope you’ll join us this spring for talks and presentations related
to our ongoing research projects in art and science, and the
Anthropocene. Over the past years, we have developed a deep and
abiding interdisciplinary research practice related to these themes,
working with diverse disciplines that are fortified through oppositions,
collaborations and the celebration of new perspectives. We have shared
our different fields of experience, expertise and resources to catalyze
meaningful responses to research, pedagogy, communication and outreach,
and in doing so build responses that are more than the sum of their
parts. This methodology of bringing the unique perspectives and
practices of artists and curators to academic units presents an
opportunity to foster new modes of knowledge exchange. In this spirit,
we hope you’ll join us in thinking through these critical areas of
inquiry.

Ars Scientia

Building on exhibitions like The Beautiful Brain and Drift, the Ars Scientia research project connects artists with physicists to explore the intersections between the disciplines of art and science. A collaboration between the Belkin, the Department of Physics and Astronomy, and the Blusson Quantum Matter Institute [QMI], [emphases mine] this spring’s artists’ residencies culminate in a series of talks by JG Mair, Scott Billings and Timothy Taylor, followed by a symposium in May with keynote speaker Kavita Philip.

Tuesday, March 28 [2023] at 1 pm [PT]

Artist Talk with Scott Billings

Tuesday, April 4 [2023] at 2 pm [PT]

Artist Talk with Timothy Taylor

Monday, May 15 [2023]

Symposium with keynote by Kavita Philip

…

I have more details (logistics in particular) about the Scott Billings talk, from the QMI Ars Scientia Artist Talks 2023: Latent Life by Scott Billings events page,

Please join Scott Billings for Latent Life, a presentation based on his recent research in the Ars Scientia residency. Drawing from a 1933 lecture in which Neils Bohr asserts that the impossibility of using a physical explanation for the phenomenon of life is analogous to the insufficiency of using a mechanical analysis to understand phenomena of the atom, Billings will discuss his seemingly conflicting dual practice as both visual artist and mechanical engineer. Reflecting upon a preoccupation with the animality of cinematic machine, among (many) other things, Billings will relay his recent direct experience with photonic writing [emphasis mine] at QMI’s NanoFab Lab and the wonderful new conundrum of making and exhibiting micro-sculptures that are far too small to see with the naked eye.

…

Date & time: March 28 [2023], 1:00-2:00pm [PT]

Location: 311, Brimacombe Building (2355 East Mall, Vancouver, BC V6T 1Z4)

For more information on this event, please click here.

Photonic writing and sculpture? I’m guessing the word ‘writing’ in this context doesn’t mean what it usually means. Still, it did bring back memories of the world’s smallest book. I always did wonder about the point of producing book that couldn’t be read without expensive equipment. And now, there’s sculpture that can’t be seen.

I hope Billings’s talk will shed some light on this phenomenon of artists and writers creating objects than cannot be seen with the naked eye. Scientists do this sort of thing for fun but the motivation for writers and artists seems to be about proving something and not at all about play.

To make carbon nanotubes (CNTs), reach like a giraffe

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Caption: There are dozens of varieties of nanotubes, each with a characteristic diameter and structural twist, or chiral angle. Carbon nanotubes are grown on catalytic particles using batch production methods that produce the entire gamut of chiral varieties, but Rice University scientists have come up with a new strategy for making batches with a single, desired chirality. Their theory shows chiral varieties can be selected for production when catalytic particles are drawn away at specific speeds by localized feedstock supply. The illustration depicts this and an analogous process 19th-century scientists used to describe the evolution of giraffes’ long necks due to the gradual selection of abilities to reach progressively higher for food. Credit: Illustration by Ksenia Bets/Rice University

A November 9, 2022 Rice University news release (also on EurekAlert) announces the Holy Grail (I’ve lost track of how many have been reached) has been achieved for growing batches of carbon nanotubes,

Like a giraffe stretching for leaves on a tall tree, making carbon nanotubes reach for food as they grow may lead to a long-sought breakthrough.

Materials theorists Boris Yakobson and Ksenia Bets at Rice University’s George R. Brown School of Engineering show how putting constraints on growing nanotubes could facilitate a “holy grail” of growing batches with a single desired chirality.

Their paper in Science Advances describes a strategy by which constraining the carbon feedstock in a furnace would help control the “kite” growth of nanotubes. In this method, the nanotube begins to form at the metal catalyst on a substrate, but lifts the catalyst as it grows, resembling a kite on a string.

Carbon nanotube walls are basically graphene, its hexagonal lattice of atoms rolled into a tube. Chirality refers to how the hexagons are angled within the lattice, between 0 and 30 degrees. That determines whether the nanotubes are metallic or semiconductors. The ability to grow long nanotubes in a single chirality could, for instance, enable the manufacture of highly conductive nanotube fibers or semiconductor channels of transistors.

Normally, nanotubes grow in random fashion with single and multiple walls and various chiralities. That’s fine for some applications, but many need “purified” batches that require centrifugation or other costly strategies to separate the nanotubes.

The researchers suggested hot carbon feedstock gas fed through moving nozzles could effectively lead nanotubes to grow for as long as the catalyst remains active. Because tubes with different chiralities grow at different speeds, they could then be separated by length, and slower-growing types could be completely eliminated.

One additional step that involves etching away some of the nanotubes could then allow specific chiralities to be harvested, they determined.

The lab’s work to define the mechanisms of nanotube growth led them to think about whether the speed of growth as a function of individual tubes’ chirality could be useful. The angle of “kinks” in the growing nanotubes’ edges determines how energetically amenable they are to adding new carbon atoms.

“The catalyst particles are moving as the nanotubes grow, and that’s principally important,” said lead author Bets, a researcher in Yakobson’s group. “If your feedstock keeps moving away, you get a moving window where you’re feeding some tubes and not the others.”

The paper’s reference to Lamarck giraffes — a 19th-century theory of how they evolved such long necks — isn’t entirely out of left field, Bets said.  

“It works as a metaphor because you move your ‘leaves’ away and the tubes that can reach it continue growing fast, and those that cannot just die out,” she said. “Eventually, all the nanotubes that are just a tiny bit slow will ‘die.’”

Speed is only part of the strategy. In fact, they suggest nanotubes that are a little slower should be the target to assure a harvest of single chiralities.

Because nanotubes of different chiralities grow at their own rates, a batch would likely exhibit tiers. Chemically etching the longest nanotubes would degrade them, preserving the next level of tubes. Restoring the feedstock could then allow the second-tier nanotubes to continue growing until they are ready to be culled, Bets said.

“There are three or four laboratory studies that show nanotube growth can be reversed, and we also know it can be restarted after etching,” she said. “So all the parts of our idea already exist, even if some of them are tricky. Close to equilibrium, you will have the same proportionality between growth and etching speeds for the same tubes. If it’s all nice and clean, then you can absolutely, precisely pick the tubes you target.”

The Yakobson lab won’t make them, as it focuses on theory, not experimentation. But other labs have turned past Rice theories into products like boron buckyballs.

“I’m pretty sure every single one of our reviewers were experimentalists, and they didn’t see any contradictions to it working,” Bets said. “Their only complaint, of course, was that they would like experimental results right now, but that’s not what we do.”

She hopes more than a few labs will pick up the challenge. “In terms of science, it’s usually more beneficial to give ideas to the crowd,” Bets said. “That way, those who have interest can do it in 100 different variations and see which one works. One guy trying it might take 100 years.”

Yakobson added, “We don’t want to be that ‘guy.’ We don’t have that much time.”

…

Here’s a link to and a citation for the paper,

Single-chirality nanotube synthesis by guided evolutionary selection by Boris I. Yakobson and Ksenia V. Bets. Science Advances 9 Nov 2022 Vol 8, Issue 45 DOI: 10.1126/sciadv.add4627

This paper is open access.

Coelacanth (a living fish fossil) may provide clue to making artificial organs for transplantation

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An ancient fish called a ‘living fossil’ has helped researchers understand the basics of stem cells. This will further stem cell research and be a step in the direction of creating artificial organs. The coelacanth fish is 400 million years old. Photo: Canva. Courtesy: university of Copenhagen

A December 12, 2022 University of Copenhagen press release (also on EurekAlert) describes work which may have an impact on organ transplants,

A beating heart. A complicated organ that pumps blood around the body of animals and humans. Not exactly something you associate with a Petri dish in a laboratory.

But that may change in the future, and save the lives of people whose own organs fail. And the research is now one step closer to that.

To design artificial organs you first have to understand stem cells and the genetic instructions that govern their remarkable properties.

Professor Joshua Mark Brickman at the Novo Nordisk Foundation Center for Stem Cell Medicine (reNEW) has unearthed the evolutionary origins of a master gene that acts on a network of genes instructing stem cells.

“The first step in stem cell research is to understand the gene regulatory network that supports so-called pluripotent stem cells. Understanding how their function was perfected in evolution can help provide knowledge about how to construct better stem cells,” says Joshua Mark Brickman.

Pluripotent stem cells are stem cells that can develop into all other cells. For example, heart cells. If we understand how the pluripotent stem cells develop into a heart, then we are one step closer to replicating this process in a laboratory.

What are stem cells?

Stem cells are non-specialized cells found in all multicellular organisms. Stem cells have two properties that distinguish them from other cell types. On the one hand, stem cells can undergo an unlimited number of cell divisions (mitoses), and on the other hand, stem cells have the ability to mature (differentiate) into several cell types.

A pluripotent stem cell is a cell that can develop into any other cell, such as a heart cell, hair cell or eye cell.

A ‘living fossil’ is the key to understanding stem cells

The pluripotent property of stem cells – meaning that the cells can develop into any other cell – is something that has traditionally been associated with mammals.

Now Joshua Mark Brickman and his colleagues have found that the master gene that controls stem cells and supports pluripotency also exists in a fish called coelacanth. In humans and mice this gene is called OCT4 and they found that the coelacanth version could replace the mammalian one in mouse stem cells.

In addition to the fact that the coelacanth is in a different class from mammals, it has also been called a ‘living fossil,’ since approximately 400 million years ago it developed into the form it has today. It has fins shaped like limbs and is therefore thought to resemble the first animals to move from the sea onto land.

“By studying its cells, you can go back in evolution, so to speak,” explains Assistant Professor Molly Lowndes.

Assistant Professor Woranop Sukparangsi continues: “The central factor controlling the gene network in stem cells is found in the coelacanth. This shows that the network already existed early in evolution, potentially as far back as 400 million years ago.”

And by studying the network in other species, such as this fish, the researchers can distill what the basic concepts that support a stem cell are.

“The beauty of moving back in evolution is that the organisms become simpler. For example, they have only one copy of some essential genes instead of many versions. That way, you can start to separate what is really important for stem cells and use that to improve how you grow stem cells in a dish,” says PhD student Elena Morganti.

Sharks, mice and kangaroos

In addition to the researchers finding out that the network around stem cells is much older than previously thought, and found in ancient species, they also learned how exactly evolution has modified the network of genes to support pluripotent stem cells.

The researchers looked at the stem cell genes from over 40 animals. For example sharks, mice and kangaroos. The animals were selected to provide a good sampling of the main branch points in evolution.

The researchers used artificial intelligence to build three-dimensional models of the different OCT4 proteins. The researchers could see that the general structure of the protein is maintained across evolution. While the regions of these proteins known to be important for stem cells do not change, species-specific differences in apparently unrelated regions of these proteins alter their orientation, potentially affecting how well it supports pluripotency.

“This a very exciting finding about evolution that would not have been possible prior to the advent of new technologies. You can see it as evolution cleverly thinking, we don not tinker with the ‘engine in the car’, but we can move the engine around and improve the drive train to see if it makes the car go faster,” says Joshua Mark Brickman.

…

The study is a collaborative project spanning Australia, Japan and Europe, with vital strategic partnerships with the groups of Sylvie Mazan at the Oceanological Observatory of Banyuls-sur-Mer in France and professor Guillermo Montoya at Novo Nordisk Foundation Center for Protein Research at University of Copenhagen.

Caption: Coelacanth-fish and other animals. Credit: By Woranop Sukparangsi Courtesy: University of Copenhagen

Here’s a link to and a citation for the paper,

Evolutionary origin of vertebrate OCT4/POU5 functions in supporting pluripotency by Woranop Sukparangsi, Elena Morganti, Molly Lowndes, Hélène Mayeur, Melanie Weisser, Fella Hammachi, Hanna Peradziryi, Fabian Roske, Jurriaan Hölzenspies, Alessandra Livigni, Benoit Gilbert Godard, Fumiaki Sugahara, Shigeru Kuratani, Guillermo Montoya, Stephen R. Frankenberg, Sylvie Mazan & Joshua M. Brickman. Nature Communications volume 13, Article number: 5537 (2022) DOI: https://doi.org/10.1038/s41467-022-32481-z Published: 21 September 2022

This paper is open access.

A new recipe for lignin nanoparticles

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A flexible film that does not absorb a drop of water. Photo: Aalto University / Sahar Babaeipour

A November 8, 2022 news item on phys.org announces a new material made of nanocellulose (Note: Links have been removed),

The Bioproduct Chemistry team at Aalto University [Finland] have designed a sustainable method to produce strong and flexible cellulosic films that incredibly maintain their strength even when wet.

The material is made through an innovative combination of wood-based and biodegradable polymers without any chemical modification, harnessing the maximum benefit of each component. For the co-authors in this study, sustainability is a significant motivator in understanding the chemistry of how these materials could work together and developing materials of tomorrow with the functionality we expect today.

A November 7, 2022 Aalto University press release, which originated the news item, explains the interest in cellulose and provides more detail about the research,

Cellulosic materials, which come from the cell walls of plants, have emerged as attractive, sustainable replacements for traditional plastics. However, the moisture sensitivity of cellulose and its incompatibility with many soft hydrophobic polymers are challenges to their widespread application.

From a materials design perspective, gaining the benefit of both hydrophilic cellulose and hydrophobic polymers at the same time without any chemical treatment of raw materials is mystifying. But what if we could engineer their interface with a third component, having favorable interactions with both cellulose and soft polymers such as polycaprolactone (PCL)? To achieve this goal, the team demonstrated that lignin nanoparticles with their well-defined morphology and active surface sites can interact with both cellulose, in this case cellulose nanofibrils, and PCL and act as a compatibilizer between hydrophilic cellulose and hydrophobic PCL. Although it looks complex, the solution is simple.

First, PCL dissolved in an organic solvent is mixed with the lignin nanoparticles in water. The lignin particles assembles at the oil water interface and stabilize the emulsion. Emulsions stabilizes with solid particles are called Pickering emulsions. This emulsion is then mixed with aqueous CNF suspension prior to film formation.  This Pickering emulsion strategy creates an even dispersion of a polymer within the cellulose network, increasing the wet strength and water resistance of the composite, meanwhile retaining all the positive characteristics of the cellulose fibers or fibrils. The outcomes are excellent:  the developed composite has a higher strength than pure CNF nanopaper or pure polymer in both dry and wet conditions, even after fully immersing it in water for a day. ‘When the film was taken out of the water, it looked exactly the same as when it was put into the water,’ says Kimiaei. The reason for this is that the hydrophobic polymer, with the aid of the lignin nanoparticles is now covering the cellulose surface protecting it from the water.

The composite revealed wet strength up to 87 MPa, the highest obtained wet strength for cellulosic composites developed without any direct covalent surface modifications or synthetic additives. Furthermore, this strategy added additional functionality, such as UV shielding and antioxidant properties to the developed composites, making them interesting for packaging applications.

The team at Aalto University in Finland, a country that arguably has the world’s leading experts in the forestry industry, is focused on making the most of these natural and industrial resources. ‘Building the future with forests requires a commitment to sustainable forest management and creating additional value beyond the typical biorefinery and pulp and paper industry,’ says co-author Erfan Kimiaei, a doctoral candidate at Aalto University, School of Chemical Engineering. ‘Understanding the interfacial chemistry of wood components can be the key to getting the most out of this valuable resource in building the sustainable future,’ professor Monika Österberg adds.

For experts in the field, this approach opens new possibilities to eliminate the need for cellulose chemical modification to impart new functionalities, promoting the sustainable use of natural resources from the forest. Furthermore, this research offers a generic foundation for combining hydrophilic cellulose with varied hydrophobic soft polymers to design multifunctional cellulose-based composites using only biodegradable polymers and lignocellulosic materials, taking a big step toward fully sustainable use of natural resources. As a follow up, the researchers are now exploring a broad framework to identify the sustainability of this early-stage technology in environmental and economic aspects by integrating techno-economic and life cycle assessments.

Here’s a link to and a citation for the paper,

Lignin Nanoparticles as an Interfacial Modulator in Tough and Multi-Resistant Cellulose–Polycaprolactone Nanocomposites Based on a Pickering Emulsions Strategy by Erfan Kimiaei, Muhammad Farooq, Rafael Grande, Kristoffer Meinander, Monika Österberg. Advanced Materials Interfaces Volume 9, Issue 27 September 22, 2022 2200988 DOI: https://doi.org/10.1002/admi.202200988 First published online: 25 August 2022

This paper is open access.

Graphene can be used in quantum components

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A November 3, 2022 news item on phys.org provides a brief history of graphene before announcing the latest work from ETH Zurich,

Less than 20 years ago, Konstantin Novoselov and Andre Geim first created two-dimensional crystals consisting of just one layer of carbon atoms. Known as graphene, this material has had quite a career since then.

Due to its exceptional strength, graphene is used today to reinforce products such as tennis rackets, car tires or aircraft wings. But it is also an interesting subject for fundamental research, as physicists keep discovering new, astonishing phenomena that have not been observed in other materials.

The right twist

Bilayer graphene crystals, in which the two atomic layers are slightly rotated relative to each other, are particularly interesting for researchers. About one year ago, a team of researchers led by Klaus Ensslin and Thomas Ihn at ETH Zurich’s Laboratory for Solid State Physics was able to demonstrate that twisted graphene could be used to create Josephson junctions, the fundamental building blocks of superconducting devices.

Based on this work, researchers were now able to produce the first superconducting quantum interference device, or SQUID, from twisted graphene for the purpose of demonstrating the interference of superconducting quasiparticles. Conventional SQUIDs are already being used, for instance in medicine, geology and archaeology. Their sensitive sensors are capable of measuring even the smallest changes in magnetic fields. However, SQUIDs work only in conjunction with superconducting materials, so they require cooling with liquid helium or nitrogen when in operation.

In quantum technology, SQUIDs can host quantum bits (qubits); that is, as elements for carrying out quantum operations. “SQUIDs are to superconductivity what transistors are to semiconductor technology—the fundamental building blocks for more complex circuits,” Ensslin explains.

…

A November 3, 2022 ETH Zurich news release by Felix Würsten, which originated the news item, delves further into the work,

The spectrum is widening

The graphene SQUIDs created by doctoral student Elías Portolés are not more sensitive than their conventional counterparts made from aluminium and also have to be cooled down to temperatures lower than 2 degrees above absolute zero. “So it’s not a breakthrough for SQUID technology as such,” Ensslin says. However, it does broaden graphene’s application spectrum significantly. “Five years ago, we were already able to show that graphene could be used to build single-electron transistors. Now we’ve added superconductivity,” Ensslin says.

What is remarkable is that the graphene’s behaviour can be controlled in a targeted manner by biasing an electrode. Depending on the voltage applied, the material can be insulating, conducting or superconducting. “The rich spectrum of opportunities offered by solid-state physics is at our disposal,” Ensslin says.

Also interesting is that the two fundamental building blocks of a semiconductor (transistor) and a superconductor (SQUID) can now be combined in a single material. This makes it possible to build novel control operations. “Normally, the transistor is made from silicon and the SQUID from aluminium,” Ensslin says. “These are different materials requiring different processing technologies.”

An extremely challenging production process

Superconductivity in graphene was discovered by an MIT [Massachusetts Institute of Technology] research group five years ago, yet there are only a dozen or so experimental groups worldwide that look at this phenomenon. Even fewer are capable of converting superconducting graphene into a functioning component.

The challenge is that scientists have to carry out several delicate work steps one after the other: First, they have to align the graphene sheets at the exact right angle relative to each other. The next steps then include connecting electrodes and etching holes. If the graphene were to be heated up, as happens often during cleanroom processing, the two layers re-align the twist angle vanishes. “The entire standard semiconductor technology has to be readjusted, making this an extremely challenging job,” Portolés says.

The vision of hybrid systems

Ensslin is thinking one step ahead. Quite a variety of different qubit technologies are currently being assessed, each with its own advantages and disadvantages. For the most part, this is being done by various research groups within the National Center of Competence in Quantum Science and Technology (QSIT). If scientists succeed in coupling two of these systems using graphene, it might be possible to combine their benefits as well. “The result would be two different quantum systems on the same crystal,” Ensslin says.

This would also generate new possibilities for research on superconductivity. “With these components, we might be better able to understand how superconductivity in graphene comes about in the first place,” he adds. “All we know today is that there are different phases of superconductivity in this material, but we do not yet have a theoretical model to explain them.”

Here’s a link to and a citation for the paper,

A tunable monolithic SQUID in twisted bilayer graphene by Elías Portolés, Shuichi Iwakiri, Giulia Zheng, Peter Rickhaus, Takashi Taniguchi, Kenji Watanabe, Thomas Ihn, Klaus Ensslin & Folkert K. de Vries. Nature Nanotechnology volume 17, pages 1159–1164 (2022) Issue Date: November 2022 DOI: https://doi.org/10.1038/s41565-022-01222-0 Published online: 24 October 2022

This paper is behind a paywall.

Plant fibers (nanocellulose) for more sustainable devices

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Thank you to Junichiro Shiomi and the University of Tokyo for this image,

Caption: An artist’s interpretation of the way natural cellulose fibers are combined to form the CNF [cellulose nanofiber] yarn, and a magnified section showing the nanoscopic rod-shaped filaments within the yarn bundle. Credit: ©2022 Junichiro Shiomi

The research into cellulose nanofibers (CNFs) announced in this November 4, 2022 news item on ScienceDaily comes from the University of Tokyo,

Plant-derived materials such as cellulose often exhibit thermally insulating properties. A new material made from nanoscale cellulose fibers shows the reverse, high thermal conductivity. This makes it useful in areas previously dominated by synthetic polymer materials. Materials based on cellulose have environmental benefits over polymers, so research on this could lead to greener technological applications where thermal conductivity is needed.

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Both cellulose nanofibers/nanofibres and cellulose nanofibrils are abbreviated to CNFs. This seems a bit confusing so I went looking for an explanation and found this September 22, 2020 posting (scroll down about 35% of the way) by professor Hatsuo Ishida, Department of Macromolecular Science and Engineering at Case Western Reserve University,

Both fiber and fibril indicate long thread-like materials and their meanings are essentially the same. However, the word,”fibril,” emphasizes a thin fiber. Therefore, the use of the word, “nano fibril,” is rather redundant. The word,”fibril” is often used for distinguishing high temperature water vapor treated cellulose fibers that are spread into very thin fibers from the whiskers prepared by the acid treatment of cellulosic materials. The word,” microfibril” is more often used than “nano fibril.” Some also use the word,”cellulose nanocrystal.” Cellulose whiskers are single crystals of materials and a typical length is less than a micrometer (one of the longest cellulose whiskers can be prepared from a sea creature called tunicate), whereas the cellulose nano fibril has much longer length. This material is much easier to scale up whereas cellulose whiskers are not as easily scale up as the nano fibrils. The word fiber has no implication and it is simply a thread like object. Thus, even if the diameter is more than hundred micrometers, as long as the length is much longer (high aspect ratio), you may call it a fiber, whereas such a thick fiber is seldom called a fibril.

Thank you professor Ishida!

A November 4, 2022 University of Tokyo press release (also on EurekAlert), which originated the news item, explains the interest in nanocellulose and its thermal properties,

Cellulose is a key structural component of plant cell walls and is the reason why trees can grow to such heights. But the secret of its material strength actually lies in its overlapping nanoscopic fibers. In recent years, many commercial products have used cellulose nanofiber (CNF) materials because their strength and durability make them a good replacement for polymer-based materials such as plastics that can be detrimental to the environment. But now and for the first time, a research team led by Professor Junichiro Shiomi from the University of Tokyo’s Graduate School of Engineering has investigated previously unknown thermal properties of CNF, and their findings show these materials could be even more useful still.

“If you see plant-derived materials such as cellulose or woody biomass used in applications, it’s typically mechanical or thermally insulating properties that are being employed,” said Shiomi. “When we explored the thermal properties of a yarn made from CNF, however, we found that they show a different kind of thermal behavior, thermal conduction, and it’s very significant, around 100 times higher than that of typical woody biomass or cellulose paper.”

The reason yarn made from CNF can conduct heat so well is due to the way it’s made. Cellulose fibers in nature are very disorganized, but a process called the flow-focusing method combines cellulose fibers, orientating them in the same way, to create CNF. It’s this tightly bound and aligned bundle of rod-shaped fibers that allows heat to transfer along the bundle, whereas in a more chaotic structure it would dissipate heat more readily.

“Our main challenge was how to measure the thermal conductivity of such small physical samples and with great accuracy,” said Shiomi. “For this, we turned to a technique called T-type thermal conductivity measurement. It allowed us to measure the thermal conductivity of the rod-shaped CNF yarn samples which are only micrometers (a micrometer equaling one-thousandth of a millimeter) in diameter. But the next step for us is to perform accurate thermal tests on two-dimensional textilelike samples.”

Shiomi and his team hope that their investigation and future explorations into the use of CNF as a thermally conductive material could give engineers an alternative to some environmentally damaging polymers. In applications where heat transfer is important, such as certain electronic or computational components, it could greatly reduce the consequences of discarded electronic equipment, or e-waste, thanks to the biodegradable nature of CNF and other plant-based materials.

Here’s a link to and a citation for the paper,

Enhanced High Thermal Conductivity Cellulose Filaments via Hydrodynamic Focusing by Guantong Wang, Masaki Kudo, Kazuho Daicho, Sivasankaran Harish, Bin Xu, Cheng Shao, Yaerim Lee, Yuxuan Liao, Naoto Matsushima, Takashi Kodama, Fredrik Lundell, L. Daniel Söderberg, Tsuguyuki Saito, and Junichiro Shiomi. Nano Lett. 2022, 22, 21, 8406–8412 DOI: https://doi.org/10.1021/acs.nanolett.2c02057 Publication Date:October 25, 2022 Copyright © 2022 The Authors. Published by American Chemical Society

This paper is open access.

Powered by light: a battery-free pacemaker

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I think it looks more like a potato than a heart but it does illustrate how this new battery-free pacemaker would wrap around a heart,

Caption: An artist’s rendering shows how a new pacemaker, designed by a UArizona-led team of researchers, is able to envelop the heart. The wireless, battery-free pacemaker could be implanted with a less invasive procedure than currently possible and would cause patients less pain. Credit: Philipp Gutruff

An October 27, 2022 news item on ScienceDaily announces a technology that could make life much easier for people with pacemakers (Comment: In the image, that looks more like a potato than a heart, to me),

University of Arizona engineers lead a research team that is developing a new kind of pacemaker, which envelops the heart and uses precise targeting capabilities to bypass pain receptors and reduce patient discomfort.

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An October 27, 2022 University of Arizona news release (also on EurekAlert) by Emily Dieckman, which originated the news item, explains the reasons for the research and provides some technical details (Note: Links have been removed),

Pacemakers are lifesaving devices that regulate the heartbeats of people with chronic heart diseases like atrial fibrillation and other forms of arrhythmia. However, pacemaker implantation is an invasive procedure, and the lifesaving pacing the devices provide can be extremely painful. Additionally, pacemakers can only be used to treat a few specific types of disease.

In a paper published Wednesday [October 26, 2022] in Science Advances, a University of Arizona-led team of researchers detail the workings of a wireless, battery-free pacemaker they designed that could be implanted with a less invasive procedure than currently possible and would cause patients less pain. The study was helmed by researchers in the Gutruf Lab, led by biomedical engineering assistant professor and Craig M. Berge Faculty Fellow Philipp Gutruf.

Currently available pacemakers work by implanting one or two leads, or points of contact, into the heart with hooks or screws. If the sensors on these leads detect a dangerous irregularity, they send an electrical shock through the heart to reset the beat.

“All of the cells inside the heart get hit at one time, including the pain receptors, and that’s what makes pacing or defibrillation painful,” Gutruf said. “It affects the heart muscle as a whole.”

The device Gutruf’s team has developed, which has not yet been tested in humans, would allow pacemakers to send much more targeted signals using a new digitally manufactured mesh design that encompasses the entire heart. The device uses light and a technique called optogenetics.

Optogenetics modifies cells, usually neurons, sensitive to light, then uses light to affect the behavior of those cells. This technique only targets cardiomyocytes, the cells of the muscle that trigger contraction and make up the beat of the heart. This precision will not only reduce pain for pacemaker patients by bypassing the heart’s pain receptors, it will also allow the pacemaker to respond to different kinds of irregularities in more appropriate ways. For example, during atrial fibrillation, the upper and lower chambers of the heart beat asynchronously, and a pacemaker’s role is to get the two parts back in line.

“Whereas right now, we have to shock the whole heart to do this, these new devices can do much more precise targeting, making defibrillation both more effective and less painful,” said Igor Efimov, professor of biomedical engineering and medicine at Northwestern University, where the devices were lab-tested. “This technology could make life easier for patients all over the world, while also helping scientists and physicians learn more about how to monitor and treat the disease.”

Flexible mesh encompasses the heart

To ensure the light signals can reach many different parts of the heart, the team created a design that involves encompassing the organ, rather than implanting leads that provide limited points of contact.

The new pacemaker model consists of four petallike structures made of thin, flexible film, which contain light sources and a recording electrode. The petals, specially designed to accommodate the way the heart changes shape as it beats, fold up around the sides of the organ to envelop it, like a flower closing up at night.

“Current pacemakers record basically a simple threshold, and they will tell you, ‘This is going into arrhythmia, now shock!'” Gutruf said. “But this device has a computer on board where you can input different algorithms that allow you to pace in a more sophisticated way. It’s made for research.”

Because the system uses light to affect the heart, rather than electrical signals, the device can continue recording information even when the pacemaker needs to defibrillate. In current pacemakers, the electrical signal from the defibrillation can interfere with recording capabilities, leaving physicians with an incomplete picture of cardiac episodes. Additionally, the device does not require a battery, which could save pacemaker patients from needing to replace the battery in their device every five to seven years, as is currently the norm.

Gutruf’s team collaborated with researchers at Northwestern University on the project. While the current version of the device has been successfully demonstrated in animal models, the researchers look forward to furthering their work, which could improve the quality of life for millions of people.

The prototype looks like this,

Caption: The device uses light and a technique called optogenetics, which modifies cells that are sensitive to light, then uses light to affect the behavior of those cells.. Credit: Philipp Gutruff

Here’s a link to and a citation for the paper,

Wireless, fully implantable cardiac stimulation and recording with on-device computation for closed-loop pacing and defibrillation by Jokubas Ausra, Micah Madrid, Rose T. Yin, Jessica Hanna, Suzanne Arnott, Jaclyn A. Brennan, Roberto Peralta, David Clausen, Jakob A. Bakall, Igor R. Efimov, and Philipp Gutruf. Science Advances 26 Oct 2022 Vol 8, Issue 43 DOI: 10.1126/sciadv.abq7469

This paper is open access.