Tag Archives: Russia

Replacing nanotechnology-enabled oil spill solutions with dog fur?

Coincidentally or not, this research from Australia was announced a little more than a month after reports of a major oil spill in the Russian Arctic. A July 10, 2020 news item on phys.org announces a new technology for mopping up oil spills (Note: Links have been removed),

Oil spill disasters on land cause long-term damage for communities and the natural environment, polluting soils and sediments and contaminating groundwater.

Current methods using synthetic sorbent materials can be effective for cleaning up oil spills, but these materials are often expensive and generate large volumes of non-biodegradable plastic wastes. Now the first comparison of natural-origin sorbent materials for land-based oil spills, including peat moss, recycled human hair, and dog fur, shows that sustainable, cheaper and biodegradable options can be developed.

The University of Technology Sydney (UTS) project found that dog fur and human hair products—recycled from salon wastes and dog groomers—can be just as good as synthetic fabrics at cleaning up crude oil spills on hard land surfaces like highway roads, pavement, and sealed concrete floors. Polypropylene, a plastic, is a widely-used fabric used to clean up oil spills in aquatic environments.

A July 9, 2020 Univesity of Technology Sydney press release on EurekAlert completes the story,

“Dog fur in particular was surprisingly good at oil spill clean-up, and felted mats from human hair and fur were very easy to apply and remove from the spills.” lead author of the study, UTS Environmental Scientist Dr Megan Murray, said. Dr Murray investigates environmentally-friendly solutions for contamination and leads The Phyto Lab research group at UTS School of Life Sciences.

“This is a very exciting finding for land managers who respond to spilled oil from trucks, storage tanks, or leaking oil pipelines. All of these land scenarios can be treated effectively with sustainable-origin sorbents,” she said.

The sorbents tested included two commercially-available products, propylene and loose peat moss, as well as sustainable-origin prototypes including felted mats made of dog fur and human hair. Prototype oil-spill sorbent booms filled with dog fur and human hair were also tested. Crude oil was used to replicate an oil spill. The results of the study are published in Environments.

The research team simulated three types of land surfaces; non-porous hard surfaces, semi-porous surfaces, and sand, to recreate common oil-spill scenarios.

“We found that loose peat moss is not as effective at cleaning up oil spills on land compared to dog fur and hair products, and it is not useful at all for sandy environments.” Dr Murray said.

“Based on this research, we recommend peat moss is no longer used for this purpose. Given that peat moss is a limited resource and harvesting it requires degrading wetland ecosystems, we think this is a very important finding.” she said.

The research concluded that, for now, sandy environments like coastal beaches can still benefit from the use of polypropylene sorbents, but further exploration of sustainable-origin sorbents is planned.

The researchers say that future applications from the research include investigating felted mats of sustainable-origin sorbents for river bank stabilisation, [emphases mine] as well as the removal of pollutants from flowing polluted waters, similar to existing membrane technology.

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

Decontaminating Terrestrial Oil Spills: A Comparative Assessment of Dog Fur, Human Hair, Peat Moss and Polypropylene Sorbents by Megan L. Murray, Soeren M. Poulsen and Brad R. Murray. Environments 2020, 7(7), 52; DOI: https://doi.org/10.3390/environments7070052 Published: 8 July 2020 (This article belongs to the Special Issue Pollution Prevention/Environmental Sustainability for Industry)

This paper is open access.

As for the Russian oil spill

A June 4, 2020 British Broadcasting Corporation (BBC) news online article outlines the situation regarding the oil spill and the steps being taken to deal with it,

Russia’s President Vladimir Putin has declared a state of emergency after 20,000 tonnes of diesel oil leaked into a river within the Arctic Circle.

The spill happened when a fuel tank at a power plant near the Siberian city of Norilsk collapsed last Friday [May 29, 2020].

The power plant’s director Vyacheslav Starostin has been taken into custody until 31 July, but not yet charged.

The plant is owned by a subsidiary of Norilsk Nickel, which is the world’s leading nickel and palladium producer.

The Russian Investigative Committee (SK) has launched a criminal case over the pollution and alleged negligence, as there was reportedly a two-day delay in informing the Moscow authorities about the spill.

Ground subsidence beneath the fuel storage tanks is believed to have caused the spill. Arctic permafrost has been melting in exceptionally warm weather [more information about the weather towards the end of this posting] for this time of year.

Russian Minister for Emergencies Yevgeny Zinichev told Mr Putin that the Norilsk plant had spent two days trying to contain the spill, before alerting his ministry.

The leaked oil drifted some 12km (7.5 miles) from the accident site, turning long stretches of the Ambarnaya river crimson red.

The leaked diesel oil drifted some 12km (7.5 miles) from the site of the accident [downloaded from https://www.bbc.com/news/world-europe-52915807]

Getting back to the June 4, 2020 British Broadcasting Corporation (BBC) news online article,

“Why did government agencies only find out about this two days [May 29, 2020?) after the fact?” he asked the subsidiary’s chief, Sergei Lipin. “Are we going to learn about emergency situations from social media?”

The region’s governor, Alexander Uss, had earlier told President Putin that he became aware of the oil spill on Sunday [May 31, 2020] after “alarming information appeared in social media”.

The spill has contaminated a 350 sq km (135 sq mile) area, state media report.

The state of emergency means extra forces are going to the area to assist with the clean-up operation.

The accident is believed to be the second largest in modern Russian history in terms of volume, an expert from the World Wildlife Fund, Alexei Knizhnikov, told the AFP [Agence France Presse] news agency.

The incident has prompted stark warnings from environmental groups, who say the scale of the spill and geography of the river mean it will be difficult to clean up.

Greenpeace has compared it to the 1989 Exxon Valdez disaster in Alaska.

Oleg Mitvol, former deputy head of Russia’s environmental watchdog Rosprirodnadzor, said there had “never been such an accident in the Arctic zone”.

He said the clean-up could cost 100bn roubles (£1.2bn; $1.5bn) and take between five and 10 years.

Minister of Natural Resources Dmitry Kobylkin warned against trying to burn off such a vast quantity of fuel oil.

He proposed trying to dilute the oil with reagents. Only the emergencies ministry with military support could deal with the pollution, he said.

Barges with booms could not contain the slick because the Ambarnaya river was too shallow, he warned.

He suggested pumping the oil on to the adjacent tundra, although President Putin added: “The soil there is probably saturated [with oil] already.”

An update of the situation can be found in a July 8, 2020 Canadian Broadcasting Corporation (CBC) article (issued by Thomson Reuters),

Russia’s environmental watchdog has asked a power subsidiary of Russian mining giant Norilsk Nickel to pay almost 148 billion rubles, or $2.8 billion Cdn, in damages over an Arctic fuel spill in Siberia.

Rosprirodnadzor, the Federal Service for Supervision of Use of Natural Resources, said in a statement on Monday [July 8, 2020] that it had already sent a request for “voluntary compensation” to the subsidiary, NTEK, after calculating the damage caused by the May 29 [2020] fuel spill.

Norilsk Nickel’s Moscow-listed shares fell by 3 per cent after the watchdog’s statement.

A fuel tank at the power plant lost pressure and released 21,000 tonnes of diesel into rivers and subsoil near the city of Norilsk, 2,900 kilometres northeast of Moscow. Russian President Vladimir Putin subsequently declared a state of emergency in the region, and investigators detained three staff at the power plant.

Norilsk, a remote city of 180,000 people situated 300 kilometres inside the Arctic Circle, is built around Norilsk Nickel, the world’s leading nickel and palladium producer, and has a reputation for its pollution.

Rosprirodnadzor said the damages included the cost for nearby water bodies, estimated at 147.05 billion rubles, $2.8 billion Cdn, and for subsoil, estimated at 738.62 million roubles, $14 million Cdn.

I can’t find any August 2020 updates for the oil spill situation in Russia. (Note: There is now an oil spill in a ecologically sensitive region near Mauritius; see August 13, 2020 news item on CBC news online website.)

Exceptionally warm weather

The oil spill isn’t the only problem in the Arctic.Here’s more from a June 23, 2020 article by Matt Simon for Wired magazine (Note: A link has been removed),

On Saturday [June 20, 2020], the residents of Verkhoyansk, Russia, marked the first day of summer with 100 degree Fahrenheit temperatures. Not that they could enjoy it, really, as Verkhoyansk is in Siberia, hundreds of miles from the nearest beach. That’s much, much hotter than towns inside the Arctic Circle usually get. That 100 degrees appears to be a record, well above the average June high temperature of 68 degrees. Yet it’s likely the people of Verkhoyansk will see that record broken again in their lifetimes: The Arctic is warming twice as fast as the rest of the planet—if not faster—creating ecological chaos for the plants and animals that populate the north.

“The events over the weekend—in the last few weeks, really—with the heatwave in Siberia, all are unprecedented in terms of the magnitude of the extremes in temperature,” says Sophie Wilkinson, a wildfire scientist at McMaster University who studies northern peat fires, which themselves have grown unusually frequent in recent years as temperatures climb.

The Arctic’s extreme warming, known as Arctic amplification or polar amplification, may be due to three factors. One, the region’s reflectivity, or albedo—how much light it bounces back into space—is changing as the world warms. “What we’ve been seeing over the last 30 years is some relatively dramatic declines in sea ice in the summertime,” says University of Edinburgh global change ecologist Isla Myers-Smith, who studies the Arctic.

Since ice is white, it reflects the sun’s energy, something you’re already probably familiar with when it comes to staying cool in the summer. If you had to pick the color of T-shirt to wear when going hiking on a hot day, she says, “most of us would pick the white T-shirt, because that’s going to reflect the sun’s heat off of our back.” Similarly, Myers-Smith says, “If the sea ice melts in the Arctic, that will remove that white surface off of the ocean, and what will be exposed is this darker ocean surface that will absorb more of the sun’s heat.”

If you’re interested in the environmental consequences of the warming of the Arctic, this is a very good article.

Finishing up, I wish the clean-up crews (in Russia and near Mauritius) all the best as they work in the midst of a pandemic, as well as, an environmental disaster (both the oil spill and the warming of the Arctic).

Second order memristor

I think this is my first encounter with a second-order memristor. An August 28, 2019 news item on Nanowerk announces the research (Note: A link has been removed),

Researchers from the Moscow Institute of Physics and Technology [MIPT} have created a device that acts like a synapse in the living brain, storing information and gradually forgetting it when not accessed for a long time. Known as a second-order memristor, the new device is based on hafnium oxide and offers prospects for designing analog neurocomputers imitating the way a biological brain learns.

An August 28, 2019 MIPT press release (also on EurekAlert), which originated the news item, provides an explanation for neuromorphic computing (analog neurocomputers; brainlike computing), the difference between a first-order and second-order memristor, and an in depth view of the research,

Neurocomputers, which enable artificial intelligence, emulate the way the brain works. It stores data in the form of synapses, a network of connections between the nerve cells, or neurons. Most neurocomputers have a conventional digital architecture and use mathematical models to invoke virtual neurons and synapses.

Alternatively, an actual on-chip electronic component could stand for each neuron and synapse in the network. This so-called analog approach has the potential to drastically speed up computations and reduce energy costs.

The core component of a hypothetical analog neurocomputer is the memristor. The word is a portmanteau of “memory” and “resistor,” which pretty much sums up what it is: a memory cell acting as a resistor. Loosely speaking, a high resistance encodes a zero, and a low resistance encodes a one. This is analogous to how a synapse conducts a signal between two neurons (one), while the absence of a synapse results in no signal, a zero.

But there is a catch: In an actual brain, the active synapses tend to strengthen over time, while the opposite is true for inactive ones. This phenomenon known as synaptic plasticity is one of the foundations of natural learning and memory. It explains the biology of cramming for an exam and why our seldom accessed memories fade.

Proposed in 2015, the second-order memristor is an attempt to reproduce natural memory, complete with synaptic plasticity. The first mechanism for implementing this involves forming nanosized conductive bridges across the memristor. While initially decreasing resistance, they naturally decay with time, emulating forgetfulness.

“The problem with this solution is that the device tends to change its behavior over time and breaks down after prolonged operation,” said the study’s lead author Anastasia Chouprik from MIPT’s Neurocomputing Systems Lab. “The mechanism we used to implement synaptic plasticity is more robust. In fact, after switching the state of the system 100 billion times, it was still operating normally, so my colleagues stopped the endurance test.”

Instead of nanobridges, the MIPT team relied on hafnium oxide to imitate natural memory. This material is ferroelectric: Its internal bound charge distribution — electric polarization — changes in response to an external electric field. If the field is then removed, the material retains its acquired polarization, the way a ferromagnet remains magnetized.

The physicists implemented their second-order memristor as a ferroelectric tunnel junction — two electrodes interlaid with a thin hafnium oxide film (fig. 1, right). The device can be switched between its low and high resistance states by means of electric pulses, which change the ferroelectric film’s polarization and thus its resistance.

“The main challenge that we faced was figuring out the right ferroelectric layer thickness,” Chouprik added. “Four nanometers proved to be ideal. Make it just one nanometer thinner, and the ferroelectric properties are gone, while a thicker film is too wide a barrier for the electrons to tunnel through. And it is only the tunneling current that we can modulate by switching polarization.”

What gives hafnium oxide an edge over other ferroelectric materials, such as barium titanate, is that it is already used by current silicon technology. For example, Intel has been manufacturing microchips based on a hafnium compound since 2007. This makes introducing hafnium-based devices like the memristor reported in this story far easier and cheaper than those using a brand-new material.

In a feat of ingenuity, the researchers implemented “forgetfulness” by leveraging the defects at the interface between silicon and hafnium oxide. Those very imperfections used to be seen as a detriment to hafnium-based microprocessors, and engineers had to find a way around them by incorporating other elements into the compound. Instead, the MIPT team exploited the defects, which make memristor conductivity die down with time, just like natural memories.

Vitalii Mikheev, the first author of the paper, shared the team’s future plans: “We are going to look into the interplay between the various mechanisms switching the resistance in our memristor. It turns out that the ferroelectric effect may not be the only one involved. To further improve the devices, we will need to distinguish between the mechanisms and learn to combine them.”

According to the physicists, they will move on with the fundamental research on the properties of hafnium oxide to make the nonvolatile random access memory cells more reliable. The team is also investigating the possibility of transferring their devices onto a flexible substrate, for use in flexible electronics.

Last year, the researchers offered a detailed description of how applying an electric field to hafnium oxide films affects their polarization. It is this very process that enables reducing ferroelectric memristor resistance, which emulates synapse strengthening in a biological brain. The team also works on neuromorphic computing systems with a digital architecture.

MIPT has provided this image illustrating the research,

Caption: The left image shows a synapse from a biological brain, the inspiration behind its artificial analogue (right). The latter is a memristor device implemented as a ferroelectric tunnel junction — that is, a thin hafnium oxide film (pink) interlaid between a titanium nitride electrode (blue cable) and a silicon substrate (marine blue), which doubles up as the second electrode. Electric pulses switch the memristor between its high and low resistance states by changing hafnium oxide polarization, and therefore its conductivity. Credit: Elena Khavina/MIPT Press Office

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

Ferroelectric Second-Order Memristor by Vitalii Mikheev, Anastasia Chouprik, Yury Lebedinskii, Sergei Zarubin, Yury Matveyev, Ekaterina Kondratyuk, Maxim G. Kozodaev, Andrey M. Markeev, Andrei Zenkevich, Dmitrii Negrov. ACS Appl. Mater. Interfaces 2019113532108-32114 DOI: https://doi.org/10.1021/acsami.9b08189 Publication Date:August 12, 2019 Copyright © 2019 American Chemical Society

This paper is behind a paywall.

Memristor-based neural network and the biosimilar principle of learning

Once you get past the technical language (there’s a lot of it), you’ll find that they make the link between biomimicry and memristors explicit. Admittedly I’m not an expert but if I understand the research correctly, the scientists are suggesting that the algorithms used in machine learning today cannot allow memristors to be properly integrated for use in true neuromorphic computing and this work from Russia and Greece points to a new paradigm. If you understand it differently, please do let me know in the comments.

A July 12, 2019 news item on Nanowerk kicks things off (Note: A link has been removed),

Lobachevsky University scientists together with their colleagues from the National Research Center “Kurchatov Institute” (Moscow) and the National Research Center “Demokritos” (Athens) are working on the hardware implementation of a spiking neural network based on memristors.

The key elements of such a network, along with pulsed neurons, are artificial synaptic connections that can change the strength (weight) of connection between neurons during the learning (Microelectronic Engineering, “Yttria-stabilized zirconia cross-point memristive devices for neuromorphic applications”).

For this purpose, memristive devices based on metal-oxide-metal nanostructures developed at the UNN Physics and Technology Research Institute (PTRI) are suitable, but their use in specific spiking neural network architectures developed at the Kurchatov Institute requires demonstration of biologically plausible learning principles.

Caption: Cross-section image of the metal-oxide-metal memristive structure based on ZrO2(Y) polycrystalline film (a); corresponding schematic view of the cross-point memristive device (b); STDP dependencies of memristive device conductance changes for different delay values between pre- and postsynaptic neuron spikes (c); photographs of a microchip and an array of memristive devices in a standard cermet casing (d); the simplest spiking neural network architecture learning on the basis of local rules for changing memristive weights (e). Credit: Lobachevsky University

A July 12, 2019 (?) Lobachevsky University press release (also on EurekAlert), which originated the news item, delves further into the work,

The biological mechanism of learning of neural systems is described by Hebb’s rule, according to which learning occurs as a result of an increase in the strength of connection  (synaptic weight) between simultaneously active neurons, which indicates the presence of a causal relationship in their excitation. One of the clarifying forms of this fundamental rule is plasticity, which depends on the time of arrival of pulses (Spike-Timing Dependent Plasticity – STDP).

In accordance with STDP, synaptic weight increases if the postsynaptic neuron generates a pulse (spike) immediately after the presynaptic one, and vice versa, the synaptic weight decreases if the postsynaptic neuron generates a spike right before the presynaptic one. Moreover, the smaller the time difference Δt between the pre- and postsynaptic spikes, the more pronounced the weight change will be.

According to one of the researchers, Head of the UNN PTRI laboratory Alexei Mikhailov, in order to demonstrate the STDP principle, memristive nanostructures based on yttria-stabilized zirconia (YSZ) thin films were used. YSZ is a well-known solid-state electrolyte with high oxygen ion mobility.

“Due to a specified concentration of oxygen vacancies, which is determined by the controlled concentration of yttrium impurities, and the heterogeneous structure of the films obtained by magnetron sputtering, such memristive structures demonstrate controlled bipolar switching between different resistive states in a wide resistance range. The switching is associated with the formation and destruction of conductive channels along grain boundaries in the polycrystalline ZrO2 (Y) film,” notes Alexei Mikhailov.

An array of memristive devices for research was implemented in the form of a microchip mounted in a standard cermet casing, which facilitates the integration of the array into a neural network’s analog circuit. The full technological cycle for creating memristive microchips is currently implemented at the UNN PTRI. In the future, it is possible to scale the devices down to the minimum size of about 50 nm, as was established by Greek partners.
Our studies of the dynamic plasticity of the memoristive devices, continues Alexey Mikhailov, have shown that the form of the conductance change depending on Δt is in good agreement with the STDP learning rules. It should be also noted that if the initial value of the memristor conductance is close to the maximum, it is easy to reduce the corresponding weight while it is difficult to enhance it, and in the case of a memristor with a minimum conductance in the initial state, it is difficult to reduce its weight, but it is easy to enhance it.

According to Vyacheslav Demin, director-coordinator in the area of nature-like technologies of the Kurchatov Institute, who is one of the ideologues of this work, the established pattern of change in the memristor conductance clearly demonstrates the possibility of hardware implementation of the so-called local learning rules. Such rules for changing the strength of synaptic connections depend only on the values ​​of variables that are present locally at each time point (neuron activities and current weights).

“This essentially distinguishes such principle from the traditional learning algorithm, which is based on global rules for changing weights, using information on the error values ​​at the current time point for each neuron of the output neural network layer (in a widely popular group of error back propagation methods). The traditional principle is not biosimilar, it requires “external” (expert) knowledge of the correct answers for each example presented to the network (that is, they do not have the property of self-learning). This principle is difficult to implement on the basis of memristors, since it requires controlled precise changes of memristor conductances, as opposed to local rules. Such precise control is not always possible due to the natural variability (a wide range of parameters) of memristors as analog elements,” says Vyacheslav Demin.

Local learning rules of the STDP type implemented in hardware on memristors provide the basis for autonomous (“unsupervised”) learning of a spiking neural network. In this case, the final state of the network does not depend on its initial state, but depends only on the learning conditions (a specific sequence of pulses). According to Vyacheslav Demin, this opens up prospects for the application of local learning rules based on memristors when solving artificial intelligence problems with the use of complex spiking neural network architectures.

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

Yttria-stabilized zirconia cross-point memristive devices for neuromorphic applications by A. V. Emelyanov, K. E. Nikiruy, A. Demin, V. V. Rylkov, A. I. Belov, D. S. Korolev, E. G. Gryaznov, D. A. Pavlov, O. N. Gorshkov, A. N. Mikhaylov, P. Dimitrakis. Microelectronic Engineering Volume 215, 15 July 2019, 110988 First available online 16 May 2019

This paper is behind a paywall.

Canadian researchers develop bone implant material from cellulose nanocrystals (CNC) while Russian scientists restore internal structure of bone with polycaprolactone nanofibers

Two research groups are working to the same end where bone marrow is concerned, encourage bone cell growth, but they are using different strategies.

University of British Columbia and McMaster University (Canada)

Caption: Researchers treated nanocrystals derived from plant cellulose so that they can link up and form a strong but lightweight sponge (an aerogel) that can compress or expand as needed to completely fill out a bone cavity. Credit: Clare Kiernan, UBC

The samples look a little like teeth, don’t they?

Before diving into the research news, there’s a terminology issue that should be noted as you’ll see when you read the news/press releases. Nanocrystal cellulose/nanocrystalline cellulose (NCC) is a term coined by Canadian researchers. Since those early day, most researchers, internationally, have adopted the term cellulose nanocrystals (CNC) as the standard term. It fits better with the naming conventions for other nnanocellulose materials such as cellulose nanofibrils, etc. By the way, a Canadian company (CelluForce) that produces CNC retained the term nanocrystalline cellulose (NCC) as a trademark for the product, CelluForce NCC®.

For anyone not familiar with aerogels, what the University of British Columbia (UBC) and McMaster University researchers are developing, are also popularly known known as ‘frozen smoke’ (see the Aerogel Wikipedia entry for more).

A March 19, 2019 news item on ScienceDaily announces the research,

Researchers from the University of British Columbia and McMaster University have developed what could be the bone implant material of the future: an airy, foamlike substance that can be injected into the body and provide scaffolding for the growth of new bone.

It’s made by treating nanocrystals derived from plant cellulose so that they link up and form a strong but lightweight sponge — technically speaking, an aerogel — that can compress or expand as needed to completely fill out a bone cavity.

A March 19, 2019 UBC news release (also on EurekAlert), which originated the news item, describes the research in more detail,

“Most bone graft or implants are made of hard, brittle ceramic that doesn’t always conform to the shape of the hole, and those gaps can lead to poor growth of the bone and implant failure,” said study author Daniel Osorio, a PhD student in chemical engineering at McMaster. “We created this cellulose nanocrystal aerogel as a more effective alternative to these synthetic materials.”

For their research, the team worked with two groups of rats, with the first group receiving the aerogel implants and the second group receiving none. Results showed that the group with implants saw 33 per cent more bone growth at the three-week mark and 50 per cent more bone growth at the 12-week mark, compared to the controls.

“These findings show, for the first time in a lab setting, that a cellulose nanocrystal aerogel can support new bone growth,” said study co-author Emily Cranston, a professor of wood science and chemical and biological engineering who holds the President’s Excellence Chair in Forest Bio-products at UBC. She added that the implant should break down into non-toxic components in the body as the bone starts to heal.

The innovation can potentially fill a niche in the $2-billion bone graft market in North America, said study co-author Kathryn Grandfield, a professor of materials science and engineering, and biomedical engineering at McMaster who supervised the work.

“We can see this aerogel being used for a number of applications including dental implants and spinal and joint replacement surgeries,” said Grandfield. “And it will be economical because the raw material, the nanocellulose, is already being produced in commercial quantities.”

The researchers say it will be some time before the aerogel makes it out of the lab and into the operating room.

“This summer, we will study the mechanisms between the bone and implant that lead to bone growth,” said Grandfield. “We’ll also look at how the implant degrades using advanced microscopes. After that, more biological testing will be required before it is ready for clinical trials.”

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

Cross-linked cellulose nanocrystal aerogels as viable bone tissue scaffolds by Daniel A. Osorio, Bryan E. J. Lee, Jacek M. Kwiecien, Xiaoyue Wang, Iflah Shahid, Ariana L. Hurley, Emily D. Cranston and Kathryn Grandfield. Acta Biomaterialia Volume 87, 15 March 2019, Pages 152-165 DOI: https://doi.org/10.1016/j.actbio.2019.01.049

This paper is behind a paywall

Now for the Russian team.

National University of Science and Technology “MISIS” (formerly part of the Moscow Mining Academy)

These scientists have adopted a different strategy as you’ll see in the March 19, 2019 news item on Nanwerk, which, coincidentally, was published on the same day as the Canadian research,

Scientists from the National University of Science and Technology “MISIS” developed a nanomaterial, which will be able to rstore the internal structure of bones damaged due to osteoporosis and osteomyelitis. A special bioactive coating of the material helped to increase the rate of division of bone cells by 3 times. In the future, it can allow to abandon bone marrow transplantation and patients will no longer need to wait for suitable donor material.

A March 19, 2019 National University of Science and Technology (MISIS) press release (also on EurekAlert), which originated the news item, provides detail about the impetus for the research and the technique being developed,

Such diseases as osteoporosis and osteomyelitis cause irreversible degenerative changes in the bone structure. Such diseases require serious complex treatment and surgery and transplantation of the destroyed bone marrow in severe stages. Donor material should have a number of compatibility indicators and even close relationship with the donor cannot guarantee full compatibility.

Research group from the National University of Science and Technology “MISIS” (NUST MISIS), led by Anton Manakhov (Laboratory for Inorganic Nanomaterials) developed material that will allow to restore damaged internal bone structure without bone marrow transplantation.
It is based on nanofibers of polycaprolactone, which is biocompatible self-dissolvable material. Earlier, the same research group has already worked with this material: by adding antibiotics to the nanofibers, scientists have managed to create non-changeable healing bandages.

“If we want the implant to take, not only biocompatibility is needed, but also activation of the natural cell growth on the surface of the material. Polycaprolactone as such is a hydrophobic material, meaning, and cells feel uncomfortable on its surface. They gather on the smooth surface and divide extremely slow”, Elizaveta Permyakova, one of the co-authors and researcher at NUST MISIS Laboratory for Inorganic Nanomaterials, explains.

To increase the hydrophilicity of the material, a thin layer of bioactive film consisting of titanium, calcium, phosphorus, carbon, oxygen and nitrogen (TiCaPCON) was deposited on it. The structure of nanofibers identical to the cell surface was preserved. These films, when immersed in a special salt medium, which chemical composition is identical to human blood plasma, are able to form on its surface a special layer of calcium and phosphorus, which in natural conditions forms the main part of the bone. Due to the chemical similarity and the structure of nanofibers, new bone tissue begins to grow rapidly on this layer. Most importantly, polycaprolactone nanofibers dissolve, having fulfilled their functions. Only new “native” tissue remains in the bone.

In the experimental part of the study, the researchers compared the rate of division of osteoblastic bone cells on the surface of the modified and unmodified material. It was found that the modified material TiCaPCON has a high hydrophilicity. In contrast to the unmodified material, the cells on its surface felt clearly more comfortable, and divided three times faster.

According to scientists, such results open up great prospects for further work with modified polycaprolactone nanofibers as an alternative to bone marrow transplantation.

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

Bioactive TiCaPCON-coated PCL nanofibers as a promising material for bone tissue engineering by Anton Manakhov, Elizaveta S. Permyakova, Sergey Ershov, Alexander Sheveyko, Andrey Kovalskii, Josef Polčák, Irina Y. Zhitnyak, Natalia A. Gloushankova, Lenka Zajíčková, Dmitry V. Shtansky. Applied Surface Science Volume 479, 15 June 2019, Pages 796-802 DOI: https://doi.org/10.1016/j.apsusc.2019.02.163

This paper is behind a paywall.

Cellulose biosensor heralds new bioimaging approach to tissue engineering

I keep an eye on how nanocellulose is being used in various applications and I’m not sure that this cellulose biosensor quite fits the bill as nanocellulose, nonetheless, it’s interesting and that’s enough for me. From a December 12, 2018 Sechenov University (Russia) press release on EurekAlert,

I.M. Sechenov First Moscow State Medical University teamed up together with Irish colleagues to develop a new imaging approach for tissue engineering. The team produced so-called ‘hybrid biosensor’ scaffold materials, which are based on cellulose matrices labeled with pH- and calcium-sensitive fluorescent proteins. These materials enable visualization of the metabolism and other important biomarkers in the engineered artificial tissues by microscopy. The results of the work were published in the Acta Biomaterialia journal.
The success of tissue engineering is based on the use of scaffold matrices – materials that support the viability and direct the growth of cells, tissues, and organoids. Scaffolds are important for basic and applied biomedical research, tissue engineering and regenerative medicine, and are promising for development of new therapeutics. However, the ability ‘to see’ what happens within the scaffolds during the tissue growth poses a significant research challenge

“We developed a new approach allowing visualization of scaffold-grown tissue and cells by using labeling with biosensor fluorescent proteins. Due to the high specificity of labeling and the use of fluorescence microscopy FLIM, we can quantify changes in pH and calcium in the vicinity of cells,” says Dr. Ruslan Dmitriev, Group Leader at the University College Cork and the Institute for Regenerative Medicine (I.M. Sechenov First Moscow State Medical University).
To achieve the specific labeling of cellulose matrices, researchers used well-known cellulose-binding proteins. The use of extracellular pH- and calcium-sensitive biosensors allow for analysis of cell metabolism: indeed, the extracellular acidification is directly associated with the balance of cell energy production pathways and the glycolytic flux (release of lactate). It is also a frequent hallmark of cancer and transformed cell types. On the other hand, calcium plays a key role in the extra- and intracellular signaling affecting cell growth and differentiation.

The approach was tested on different types of cellulose matrices (bacterial and produced from decellularised plant tissues) using 3D culture of human colon cancer cells and stem-cell derived mouse small intestinal organoids. The scaffolds informed on changes in the extracellular acidification and were used together with the analysis of real-time oxygenation of intestinal organoids. The resulting data can be presented in the form of colour maps, corresponding to the areas of cell growth within different microenvironments.

“Our results open new prospects in the imaging of tissue-engineered constructs for regenerative medicine. They enable deeper understanding of tissue metabolism in 3D and are also highly promising for commercialisation,” concludes Dr. Dmitriev.

The researchers have provided an image to illustrate their work,

Caption: A 3D reconstruction of a cellulose matrix stained with a pH-sensitive biosensor. Credit: Dr. R. Dmitriev

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

Cellulose-based scaffolds for fluorescence lifetime imaging-assisted tissue engineering by Neil O’Donnell, Irina A. Okkelman, Peter Timashev, Tatyana I.Gromovykh, Dmitri B. Papkovsky, Ruslan I.Dmitriev. Acta Biomaterialia Volume 80, 15 October 2018, Pages 85-96 DOI: https://doi.org/10.1016/j.actbio.2018.09.034

This paper is behind a paywall.

Two approaches to memristors

Within one day of each other in October 2018, two different teams working on memristors with applications to neuroprosthetics and neuromorphic computing (brainlike computing) announced their results.

Russian team

An October 15, 2018 (?) Lobachevsky University press release (also published on October 15, 2018 on EurekAlert) describes a new approach to memristors,

Biological neurons are coupled unidirectionally through a special junction called a synapse. An electrical signal is transmitted along a neuron after some biochemical reactions initiate a chemical release to activate an adjacent neuron. These junctions are crucial for cognitive functions, such as perception, learning and memory.

A group of researchers from Lobachevsky University in Nizhny Novgorod investigates the dynamics of an individual memristive device when it receives a neuron-like signal as well as the dynamics of a network of analog electronic neurons connected by means of a memristive device. According to Svetlana Gerasimova, junior researcher at the Physics and Technology Research Institute and at the Neurotechnology Department of Lobachevsky University, this system simulates the interaction between synaptically coupled brain neurons while the memristive device imitates a neuron axon.

A memristive device is a physical model of Chua’s [Dr. Leon Chua, University of California at Berkeley; see my May 9, 2008 posting for a brief description Dr. Chua’s theory] memristor, which is an electric circuit element capable of changing its resistance depending on the electric signal received at the input. The device based on a Au/ZrO2(Y)/TiN/Ti structure demonstrates reproducible bipolar switching between the low and high resistance states. Resistive switching is determined by the oxidation and reduction of segments of conducting channels (filaments) in the oxide film when voltage with different polarity is applied to it. In the context of the present work, the ability of a memristive device to change conductivity under the action of pulsed signals makes it an almost ideal electronic analog of a synapse.

Lobachevsky University scientists and engineers supported by the Russian Science Foundation (project No.16-19-00144) have experimentally implemented and theoretically described the synaptic connection of neuron-like generators using the memristive interface and investigated the characteristics of this connection.

“Each neuron is implemented in the form of a pulse signal generator based on the FitzHugh-Nagumo model. This model provides a qualitative description of the main neurons’ characteristics: the presence of the excitation threshold, the presence of excitable and self-oscillatory regimes with the possibility of a changeover. At the initial time moment, the master generator is in the self-oscillatory mode, the slave generator is in the excitable mode, and the memristive device is used as a synapse. The signal from the master generator is conveyed to the input of the memristive device, the signal from the output of the memristive device is transmitted to the input of the slave generator via the loading resistance. When the memristive device switches from a high resistance to a low resistance state, the connection between the two neuron-like generators is established. The master generator goes into the oscillatory mode and the signals of the generators are synchronized. Different signal modulation mode synchronizations were demonstrated for the Au/ZrO2(Y)/TiN/Ti memristive device,” – says Svetlana Gerasimova.

UNN researchers believe that the next important stage in the development of neuromorphic systems based on memristive devices is to apply such systems in neuroprosthetics. Memristive systems will provide a highly efficient imitation of synaptic connection due to the stochastic nature of the memristive phenomenon and can be used to increase the flexibility of the connections for neuroprosthetic purposes. Lobachevsky University scientists have vast experience in the development of neurohybrid systems. In particular, a series of experiments was performed with the aim of connecting the FitzHugh-Nagumo oscillator with a biological object, a rat brain hippocampal slice. The signal from the electronic neuron generator was transmitted through the optic fiber communication channel to the bipolar electrode which stimulated Schaffer collaterals (axons of pyramidal neurons in the CA3 field) in the hippocampal slices. “We are going to combine our efforts in the design of artificial neuromorphic systems and our experience of working with living cells to improve flexibility of prosthetics,” concludes S. Gerasimova.

The results of this research were presented at the 38th International Conference on Nonlinear Dynamics (Dynamics Days Europe) at Loughborough University (Great Britain).

This diagram illustrates an aspect of the work,

Caption: Schematic of electronic neurons coupling via a memristive device. Credit: Lobachevsky University

US team

The American Institute of Physics (AIP) announced the publication of a ‘memristor paper’ by a team from the University of Southern California (USC) in an October 16, 2018 news item on phys.org,

Just like their biological counterparts, hardware that mimics the neural circuitry of the brain requires building blocks that can adjust how they synapse, with some connections strengthening at the expense of others. One such approach, called memristors, uses current resistance to store this information. New work looks to overcome reliability issues in these devices by scaling memristors to the atomic level.

An October 16, 2018 AIP news release (also on EurekAlert), which originated the news item, delves further into the particulars of this particular piece of memristor research,

A group of researchers demonstrated a new type of compound synapse that can achieve synaptic weight programming and conduct vector-matrix multiplication with significant advances over the current state of the art. Publishing its work in the Journal of Applied Physics, from AIP Publishing, the group’s compound synapse is constructed with atomically thin boron nitride memristors running in parallel to ensure efficiency and accuracy.

The article appears in a special topic section of the journal devoted to “New Physics and Materials for Neuromorphic Computation,” which highlights new developments in physical and materials science research that hold promise for developing the very large-scale, integrated “neuromorphic” systems of tomorrow that will carry computation beyond the limitations of current semiconductors today.

“There’s a lot of interest in using new types of materials for memristors,” said Ivan Sanchez Esqueda, an author on the paper. “What we’re showing is that filamentary devices can work well for neuromorphic computing applications, when constructed in new clever ways.”

Current memristor technology suffers from a wide variation in how signals are stored and read across devices, both for different types of memristors as well as different runs of the same memristor. To overcome this, the researchers ran several memristors in parallel. The combined output can achieve accuracies up to five times those of conventional devices, an advantage that compounds as devices become more complex.

The choice to go to the subnanometer level, Sanchez said, was born out of an interest to keep all of these parallel memristors energy-efficient. An array of the group’s memristors were found to be 10,000 times more energy-efficient than memristors currently available.

“It turns out if you start to increase the number of devices in parallel, you can see large benefits in accuracy while still conserving power,” Sanchez said. Sanchez said the team next looks to further showcase the potential of the compound synapses by demonstrating their use completing increasingly complex tasks, such as image and pattern recognition.

Here’s an image illustrating the parallel artificial synapses,

Caption: Hardware that mimics the neural circuitry of the brain requires building blocks that can adjust how they synapse. One such approach, called memristors, uses current resistance to store this information. New work looks to overcome reliability issues in these devices by scaling memristors to the atomic level. Researchers demonstrated a new type of compound synapse that can achieve synaptic weight programming and conduct vector-matrix multiplication with significant advances over the current state of the art. They discuss their work in this week’s Journal of Applied Physics. This image shows a conceptual schematic of the 3D implementation of compound synapses constructed with boron nitride oxide (BNOx) binary memristors, and the crossbar array with compound BNOx synapses for neuromorphic computing applications. Credit: Ivan Sanchez Esqueda

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

Efficient learning and crossbar operations with atomically-thin 2-D material compound synapses by Ivan Sanchez Esqueda, Huan Zhao and Han Wang. The article will appear in the Journal of Applied Physics Oct. 16, 2018 (DOI: 10.1063/1.5042468).

This paper is behind a paywall.

*Title corrected from ‘Two approaches to memristors featuring’ to ‘Two approaches to memristors’ on May 31, 2019 at 1455 hours PDT.

It’s a very ‘carbony’ time: graphene jacket, graphene-skinned airplane, and schwarzite

In August 2018, I been stumbled across several stories about graphene-based products and a new form of carbon.

Graphene jacket

The company producing this jacket has as its goal “… creating bionic clothing that is both bulletproof and intelligent.” Well, ‘bionic‘ means biologically-inspired engineering and ‘intelligent‘ usually means there’s some kind of computing capability in the product. This jacket, which is the first step towards the company’s goal, is not bionic, bulletproof, or intelligent. Nonetheless, it represents a very interesting science experiment in which you, the consumer, are part of step two in the company’s R&D (research and development).

Onto Vollebak’s graphene jacket,

Courtesy: Vollebak

From an August 14, 2018 article by Jesus Diaz for Fast Company,

Graphene is the thinnest possible form of graphite, which you can find in your everyday pencil. It’s purely bi-dimensional, a single layer of carbon atoms that has unbelievable properties that have long threatened to revolutionize everything from aerospace engineering to medicine. …

Despite its immense promise, graphene still hasn’t found much use in consumer products, thanks to the fact that it’s hard to manipulate and manufacture in industrial quantities. The process of developing Vollebak’s jacket, according to the company’s cofounders, brothers Steve and Nick Tidball, took years of intensive research, during which the company worked with the same material scientists who built Michael Phelps’ 2008 Olympic Speedo swimsuit (which was famously banned for shattering records at the event).

The jacket is made out of a two-sided material, which the company invented during the extensive R&D process. The graphene side looks gunmetal gray, while the flipside appears matte black. To create it, the scientists turned raw graphite into something called graphene “nanoplatelets,” which are stacks of graphene that were then blended with polyurethane to create a membrane. That, in turn, is bonded to nylon to form the other side of the material, which Vollebak says alters the properties of the nylon itself. “Adding graphene to the nylon fundamentally changes its mechanical and chemical properties–a nylon fabric that couldn’t naturally conduct heat or energy, for instance, now can,” the company claims.

The company says that it’s reversible so you can enjoy graphene’s properties in different ways as the material interacts with either your skin or the world around you. “As physicists at the Max Planck Institute revealed, graphene challenges the fundamental laws of heat conduction, which means your jacket will not only conduct the heat from your body around itself to equalize your skin temperature and increase it, but the jacket can also theoretically store an unlimited amount of heat, which means it can work like a radiator,” Tidball explains.

He means it literally. You can leave the jacket out in the sun, or on another source of warmth, as it absorbs heat. Then, the company explains on its website, “If you then turn it inside out and wear the graphene next to your skin, it acts like a radiator, retaining its heat and spreading it around your body. The effect can be visibly demonstrated by placing your hand on the fabric, taking it away and then shooting the jacket with a thermal imaging camera. The heat of the handprint stays long after the hand has left.”

There’s a lot more to the article although it does feature some hype and I’m not sure I believe Diaz’s claim (August 14, 2018 article) that ‘graphene-based’ hair dye is perfectly safe ( Note: A link has been removed),

Graphene is the thinnest possible form of graphite, which you can find in your everyday pencil. It’s purely bi-dimensional, a single layer of carbon atoms that has unbelievable properties that will one day revolutionize everything from aerospace engineering to medicine. Its diverse uses are seemingly endless: It can stop a bullet if you add enough layers. It can change the color of your hair with no adverse effects. [emphasis mine] It can turn the walls of your home into a giant fire detector. “It’s so strong and so stretchy that the fibers of a spider web coated in graphene could catch a falling plane,” as Vollebak puts it in its marketing materials.

Not unless things have changed greatly since March 2018. My August 2, 2018 posting featured the graphene-based hair dye announcement from March 2018 and a cautionary note from Dr. Andrew Maynard (scroll down ab out 50% of the way for a longer excerpt of Maynard’s comments),

Northwestern University’s press release proudly announced, “Graphene finds new application as nontoxic, anti-static hair dye.” The announcement spawned headlines like “Enough with the toxic hair dyes. We could use graphene instead,” and “’Miracle material’ graphene used to create the ultimate hair dye.”

From these headlines, you might be forgiven for getting the idea that the safety of graphene-based hair dyes is a done deal. Yet having studied the potential health and environmental impacts of engineered nanomaterials for more years than I care to remember, I find such overly optimistic pronouncements worrying – especially when they’re not backed up by clear evidence.

These studies need to be approached with care, as the precise risks of graphene exposure will depend on how the material is used, how exposure occurs and how much of it is encountered. Yet there’s sufficient evidence to suggest that this substance should be used with caution – especially where there’s a high chance of exposure or that it could be released into the environment.

The full text of Dr. Maynard’s comments about graphene hair dyes and risk can be found here.

Bearing in mind  that graphene-based hair dye is an entirely different class of product from the jacket, I wouldn’t necessarily dismiss risks; I would like to know what kind of risk assessment and safety testing has been done. Due to their understandable enthusiasm, the brothers Tidball have focused all their marketing on the benefits and the opportunity for the consumer to test their product (from graphene jacket product webpage),

While it’s completely invisible and only a single atom thick, graphene is the lightest, strongest, most conductive material ever discovered, and has the same potential to change life on Earth as stone, bronze and iron once did. But it remains difficult to work with, extremely expensive to produce at scale, and lives mostly in pioneering research labs. So following in the footsteps of the scientists who discovered it through their own highly speculative experiments, we’re releasing graphene-coated jackets into the world as experimental prototypes. Our aim is to open up our R&D and accelerate discovery by getting graphene out of the lab and into the field so that we can harness the collective power of early adopters as a test group. No-one yet knows the true limits of what graphene can do, so the first edition of the Graphene Jacket is fully reversible with one side coated in graphene and the other side not. If you’d like to take part in the next stage of this supermaterial’s history, the experiment is now open. You can now buy it, test it and tell us about it. [emphasis mine]

How maverick experiments won the Nobel Prize

While graphene’s existence was first theorised in the 1940s, it wasn’t until 2004 that two maverick scientists, Andre Geim and Konstantin Novoselov, were able to isolate and test it. Through highly speculative and unfunded experimentation known as their ‘Friday night experiments,’ they peeled layer after layer off a shaving of graphite using Scotch tape until they produced a sample of graphene just one atom thick. After similarly leftfield thinking won Geim the 2000 Ig Nobel prize for levitating frogs using magnets, the pair won the Nobel prize in 2010 for the isolation of graphene.

Should you be interested, in beta-testing the jacket, it will cost you $695 (presumably USD); order here. One last thing, Vollebak is based in the UK.

Graphene skinned plane

An August 14, 2018 news item (also published as an August 1, 2018 Haydale press release) by Sue Keighley on Azonano heralds a new technology for airplans,

Haydale, (AIM: HAYD), the global advanced materials group, notes the announcement made yesterday from the University of Central Lancashire (UCLAN) about the recent unveiling of the world’s first graphene skinned plane at the internationally renowned Farnborough air show.

The prepreg material, developed by Haydale, has potential value for fuselage and wing surfaces in larger scale aero and space applications especially for the rapidly expanding drone market and, in the longer term, the commercial aerospace sector. By incorporating functionalised nanoparticles into epoxy resins, the electrical conductivity of fibre-reinforced composites has been significantly improved for lightning-strike protection, thereby achieving substantial weight saving and removing some manufacturing complexities.

Before getting to the photo, here’s a definition for pre-preg from its Wikipedia entry (Note: Links have been removed),

Pre-preg is “pre-impregnated” composite fibers where a thermoset polymer matrix material, such as epoxy, or a thermoplastic resin is already present. The fibers often take the form of a weave and the matrix is used to bond them together and to other components during manufacture.

Haydale has supplied graphene enhanced prepreg material for Juno, a three-metre wide graphene-enhanced composite skinned aircraft, that was revealed as part of the ‘Futures Day’ at Farnborough Air Show 2018. [downloaded from https://www.azonano.com/news.aspx?newsID=36298]

A July 31, 2018 University of Central Lancashire (UCLan) press release provides a tiny bit more (pun intended) detail,

The University of Central Lancashire (UCLan) has unveiled the world’s first graphene skinned plane at an internationally renowned air show.

Juno, a three-and-a-half-metre wide graphene skinned aircraft, was revealed on the North West Aerospace Alliance (NWAA) stand as part of the ‘Futures Day’ at Farnborough Air Show 2018.

The University’s aerospace engineering team has worked in partnership with the Sheffield Advanced Manufacturing Research Centre (AMRC), the University of Manchester’s National Graphene Institute (NGI), Haydale Graphene Industries (Haydale) and a range of other businesses to develop the unmanned aerial vehicle (UAV), which also includes graphene batteries and 3D printed parts.

Billy Beggs, UCLan’s Engineering Innovation Manager, said: “The industry reaction to Juno at Farnborough was superb with many positive comments about the work we’re doing. Having Juno at one the world’s biggest air shows demonstrates the great strides we’re making in leading a programme to accelerate the uptake of graphene and other nano-materials into industry.

“The programme supports the objectives of the UK Industrial Strategy and the University’s Engineering Innovation Centre (EIC) to increase industry relevant research and applications linked to key local specialisms. Given that Lancashire represents the fourth largest aerospace cluster in the world, there is perhaps no better place to be developing next generation technologies for the UK aerospace industry.”

Previous graphene developments at UCLan have included the world’s first flight of a graphene skinned wing and the launch of a specially designed graphene-enhanced capsule into near space using high altitude balloons.

UCLan engineering students have been involved in the hands-on project, helping build Juno on the Preston Campus.

Haydale supplied much of the material and all the graphene used in the aircraft. Ray Gibbs, Chief Executive Officer, said: “We are delighted to be part of the project team. Juno has highlighted the capability and benefit of using graphene to meet key issues faced by the market, such as reducing weight to increase range and payload, defeating lightning strike and protecting aircraft skins against ice build-up.”

David Bailey Chief Executive of the North West Aerospace Alliance added: “The North West aerospace cluster contributes over £7 billion to the UK economy, accounting for one quarter of the UK aerospace turnover. It is essential that the sector continues to develop next generation technologies so that it can help the UK retain its competitive advantage. It has been a pleasure to support the Engineering Innovation Centre team at the University in developing the world’s first full graphene skinned aircraft.”

The Juno project team represents the latest phase in a long-term strategic partnership between the University and a range of organisations. The partnership is expected to go from strength to strength following the opening of the £32m EIC facility in February 2019.

The next step is to fly Juno and conduct further tests over the next two months.

Next item, a new carbon material.


I love watching this gif of a schwarzite,

The three-dimensional cage structure of a schwarzite that was formed inside the pores of a zeolite. (Graphics by Yongjin Lee and Efrem Braun)

An August 13, 2018 news item on Nanowerk announces the new carbon structure,

The discovery of buckyballs [also known as fullerenes, C60, or buckminsterfullerenes] surprised and delighted chemists in the 1980s, nanotubes jazzed physicists in the 1990s, and graphene charged up materials scientists in the 2000s, but one nanoscale carbon structure – a negatively curved surface called a schwarzite – has eluded everyone. Until now.

University of California, Berkeley [UC Berkeley], chemists have proved that three carbon structures recently created by scientists in South Korea and Japan are in fact the long-sought schwarzites, which researchers predict will have unique electrical and storage properties like those now being discovered in buckminsterfullerenes (buckyballs or fullerenes for short), nanotubes and graphene.

An August 13, 2018 UC Berkeley news release by Robert Sanders, which originated the news item, describes how the Berkeley scientists and the members of their international  collaboration from Germany, Switzerland, Russia, and Italy, have contributed to the current state of schwarzite research,

The new structures were built inside the pores of zeolites, crystalline forms of silicon dioxide – sand – more commonly used as water softeners in laundry detergents and to catalytically crack petroleum into gasoline. Called zeolite-templated carbons (ZTC), the structures were being investigated for possible interesting properties, though the creators were unaware of their identity as schwarzites, which theoretical chemists have worked on for decades.

Based on this theoretical work, chemists predict that schwarzites will have unique electronic, magnetic and optical properties that would make them useful as supercapacitors, battery electrodes and catalysts, and with large internal spaces ideal for gas storage and separation.

UC Berkeley postdoctoral fellow Efrem Braun and his colleagues identified these ZTC materials as schwarzites based of their negative curvature, and developed a way to predict which zeolites can be used to make schwarzites and which can’t.

“We now have the recipe for how to make these structures, which is important because, if we can make them, we can explore their behavior, which we are working hard to do now,” said Berend Smit, an adjunct professor of chemical and biomolecular engineering at UC Berkeley and an expert on porous materials such as zeolites and metal-organic frameworks.

Smit, the paper’s corresponding author, Braun and their colleagues in Switzerland, China, Germany, Italy and Russia will report their discovery this week in the journal Proceedings of the National Academy of Sciences. Smit is also a faculty scientist at Lawrence Berkeley National Laboratory.

Playing with carbon

Diamond and graphite are well-known three-dimensional crystalline arrangements of pure carbon, but carbon atoms can also form two-dimensional “crystals” — hexagonal arrangements patterned like chicken wire. Graphene is one such arrangement: a flat sheet of carbon atoms that is not only the strongest material on Earth, but also has a high electrical conductivity that makes it a promising component of electronic devices.

schwarzite carbon cage

The cage structure of a schwarzite that was formed inside the pores of a zeolite. The zeolite is subsequently dissolved to release the new material. (Graphics by Yongjin Lee and Efrem Braun)

Graphene sheets can be wadded up to form soccer ball-shaped fullerenes – spherical carbon cages that can store molecules and are being used today to deliver drugs and genes into the body. Rolling graphene into a cylinder yields fullerenes called nanotubes, which are being explored today as highly conductive wires in electronics and storage vessels for gases like hydrogen and carbon dioxide. All of these are submicroscopic, 10,000 times smaller than the width of a human hair.

To date, however, only positively curved fullerenes and graphene, which has zero curvature, have been synthesized, feats rewarded by Nobel Prizes in 1996 and 2010, respectively.

In the 1880s, German physicist Hermann Schwarz investigated negatively curved structures that resemble soap-bubble surfaces, and when theoretical work on carbon cage molecules ramped up in the 1990s, Schwarz’s name became attached to the hypothetical negatively curved carbon sheets.

“The experimental validation of schwarzites thus completes the triumvirate of possible curvatures to graphene; positively curved, flat, and now negatively curved,” Braun added.

Minimize me

Like soap bubbles on wire frames, schwarzites are topologically minimal surfaces. When made inside a zeolite, a vapor of carbon-containing molecules is injected, allowing the carbon to assemble into a two-dimensional graphene-like sheet lining the walls of the pores in the zeolite. The surface is stretched tautly to minimize its area, which makes all the surfaces curve negatively, like a saddle. The zeolite is then dissolved, leaving behind the schwarzite.

soap bubble schwarzite structure

A computer-rendered negatively curved soap bubble that exhibits the geometry of a carbon schwarzite. (Felix Knöppel image)

“These negatively-curved carbons have been very hard to synthesize on their own, but it turns out that you can grow the carbon film catalytically at the surface of a zeolite,” Braun said. “But the schwarzites synthesized to date have been made by choosing zeolite templates through trial and error. We provide very simple instructions you can follow to rationally make schwarzites and we show that, by choosing the right zeolite, you can tune schwarzites to optimize the properties you want.”

Researchers should be able to pack unusually large amounts of electrical charge into schwarzites, which would make them better capacitors than conventional ones used today in electronics. Their large interior volume would also allow storage of atoms and molecules, which is also being explored with fullerenes and nanotubes. And their large surface area, equivalent to the surface areas of the zeolites they’re grown in, could make them as versatile as zeolites for catalyzing reactions in the petroleum and natural gas industries.

Braun modeled ZTC structures computationally using the known structures of zeolites, and worked with topological mathematician Senja Barthel of the École Polytechnique Fédérale de Lausanne in Sion, Switzerland, to determine which of the minimal surfaces the structures resembled.

The team determined that, of the approximately 200 zeolites created to date, only 15 can be used as a template to make schwarzites, and only three of them have been used to date to produce schwarzite ZTCs. Over a million zeolite structures have been predicted, however, so there could be many more possible schwarzite carbon structures made using the zeolite-templating method.

Other co-authors of the paper are Yongjin Lee, Seyed Mohamad Moosavi and Barthel of the École Polytechnique Fédérale de Lausanne, Rocio Mercado of UC Berkeley, Igor Baburin of the Technische Universität Dresden in Germany and Davide Proserpio of the Università degli Studi di Milano in Italy and Samara State Technical University in Russia.

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

Generating carbon schwarzites via zeolite-templating by Efrem Braun, Yongjin Lee, Seyed Mohamad Moosavi, Senja Barthel, Rocio Mercado, Igor A. Baburin, Davide M. Proserpio, and Berend Smit. PNAS August 14, 2018. 201805062; published ahead of print August 14, 2018. https://doi.org/10.1073/pnas.1805062115

This paper appears to be open access.

Build nanoparticles using techniques from the ancient Egyptians

Great Pyramid of Giza and Sphinx [downloaded from http://news.ifmo.ru/en/science/photonics/news/7731/]

Russian and German scientists have taken a closer look at the Great Pyramid as they investigate better ways of designing sensors and solar cells. From a July 30, 2018 news item on Nanowerk,

An international research group applied methods of theoretical physics to investigate the electromagnetic response of the Great Pyramid to radio waves. Scientists predicted that under resonance conditions the pyramid can concentrate electromagnetic energy in its internal chambers and under the base. The research group plans to use these theoretical results to design nanoparticles capable of reproducing similar effects in the optical range. Such nanoparticles may be used, for example, to develop sensors and highly efficient solar cells.

A July 30, 2018 ITMO University press release, which originated the news item,  expands on the theme,

While Egyptian pyramids are surrounded by many myths and legends, we have little scientifically reliable information about their physical properties. As it turns out, sometimes this information proves to be more fascinating than any fiction. This idea found confirmation in a new joint study undertaken by scientists from ITMO University and the Laser Zentrum Hannover. The physicists took an interest in how the Great Pyramid would interact with electromagnetic waves of a proportional, or resonant, length. Calculations showed that in the resonant state the pyramid can concentrate electromagnetic energy in its internal chambers as well as under its base, where the third unfinished chamber is located.

These conclusions were derived on the basis of numerical modeling and analytical methods of physics. The researchers first estimated that resonances in the pyramid can be induced by radio waves with a length ranging from 200 to 600 meters. Then they made a model of the electromagnetic response of the pyramid and calculated the extinction cross section. This value helps to estimate which part of the incident wave energy can be scattered or absorbed by the pyramid under resonant conditions. Finally, for the same conditions, the scientists obtained the electromagnetic fields distribution inside the pyramid.

3D model of the pyramid. Credit: cheops.SU
3D model of the pyramid. Credit: cheops.SU

In order to explain the results, the scientists conducted a multipole analysis. This method is widely used in physics to study the interaction between a complex object and electromagnetic field. The object scattering the field is replaced by a set of simpler sources of radiation: multipoles. The collection of multipoles radiation coincides with the field scattering by an entire object. Therefore, by knowing the type of each multipole, it is possible to predict and explain the distribution and configuration of the scattered fields in the whole system.

The Great Pyramid attracted the researchers’ attention while they were studying the interaction between light and dielectric nanoparticles. The scattering of light by nanoparticles depends on their size, shape, and refractive index of the source material. By varying these parameters, it is possible to determine the resonance scattering regimes and use them to develop devices for controlling light at the nanoscale.

“Egyptian pyramids have always attracted great attention. We as scientists were interested in them as well, and so we decided to look at the Great Pyramid as a particle resonantly dissipating radio waves. Due to the lack of information about the physical properties of the pyramid, we had to make some assumptions. For example, we assumed that there are no unknown cavities inside, and the building material has the properties of an ordinary limestone and is evenly distributed in and out of the pyramid. With these assumptions, we obtained interesting results that can have important practical applications,” says Andrey Evlyukhin, DSc, scientific supervisor and coordinator of the research.

Now the scientists plan to use the results to reproduce similar effects at the nanoscale.

Polina Kapitanova
Polina Kapitanova

“By choosing a material with suitable electromagnetic properties, we can obtain pyramidal nanoparticles with a potential for practical application in nanosensors and effective solar cells,” says Polina Kapitanova, PhD, associate at the Faculty of Physics and Engineering of ITMO University.

The research was supported by the Russian Science Foundation and the Deutsche Forschungsgemeinschaft (grants № 17-79-20379 and №16-12-10287).

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

Electromagnetic properties of the Great Pyramid: First multipole resonances and energy concentration featured by Mikhail Balezin, Kseniia V. Baryshnikova, Polina Kapitanova, and Andrey B. Evlyukhin. Journal of Applied Physics 124, 034903 (2018) https://doi.org/10.1063/1.5026556 or Journal of Applied Physics, Volume 124, Issue 3. 10.1063/1.5026556 Published Online 20 July 2018

This paper is behind a paywall..

Scientometrics and science typologies

Caption: As of 2013, there were 7.8 million researchers globally, according to UNESCO. This means that 0.1 percent of the people in the world professionally do science. Their work is largely financed by governments, yet public officials are not themselves researchers. To help governments make sense of the scientific community, Russian mathematicians have devised a researcher typology. The authors initially identified three clusters, which they tentatively labeled as “leaders,” “successors,” and “toilers.” Credit: Lion_on_helium/MIPT Press Office

A June 28, 2018 Moscow Institute of Physics and Technology (MIPT; Russia) press release (also on EurekAlert) announces some intriguing research,

Researchers in various fields, from psychology to economics, build models of human behavior and reasoning to categorize people. But it does not happen as often that scientists undertake an analysis to classify their own kind.

However, research evaluation, and therefore scientist stratification as well, remain highly relevant. Six years ago, the government outlined the objective that Russian scientists should have 50 percent more publications in Web of Science- and Scopus-indexed journals. As of 2011, papers by researchers from Russia accounted for 1.66 percent of publications globally. By 2015, this number was supposed to reach 2.44%. It did grow but this has also sparked a discussion in the scientific community about the criteria used for evaluating research work.

The most common way of gauging the impact of a researcher is in terms of his or her publications. Namely, whether they are in a prestigious journal and how many times they have been cited. As with any good idea, however, one runs the risk of overdoing it. In 2005, U.S. physicist Jorge Hirsch proposed his h-index, which takes into account the number of publications by a given researcher and the number of times they have been cited. Now, scientists are increasingly doubting the adequacy of using bibliometric data as the sole independent criterion for evaluating research work. One obvious example of a flaw of this metric is that a paper can be frequently cited to point out a mistake in it.

Scientists are increasingly under pressure to publish more often. Research that might have reasonably been published in one paper is being split up into stages for separate publication. This calls for new approaches to the evaluation of work done by research groups and individual authors. Similarly, attempts to systematize the existing methods in scientometrics and stratify scientists are becoming more relevant, too. This is arguably even more important for Russia, where the research reform has been stretching for years.

One of the challenges in scientometrics is identifying the prominent types of researchers in different fields. A typology of scientists has been proposed by Moscow Institute of Physics and Technology Professor Pavel Chebotarev, who also heads the Laboratory of Mathematical Methods for Multiagent Systems Analysis at the Institute of Control Sciences of the Russian Academy of Sciences, and Ilya Vasilyev, a master’s student at MIPT.

In their paper, the two authors determined distinct types of scientists based on an indirect analysis of the style of research work, how papers are received by colleagues, and what impact they make. A further question addressed by the authors is to what degree researcher typology is affected by the scientific discipline.

“Each science has its own style of work. Publication strategies and citation practices vary, and leaders are distinguished in different ways,” says Chebotarev. “Even within a given discipline, things may be very different. This means that it is, unfortunately, not possible to have a universal system that would apply to anyone from a biologist to a philologist.”

“All of the reasonable systems that already exist are adjusted to particular disciplines,” he goes on. “They take into account the criteria used by the researchers themselves to judge who is who in their field. For example, scientists at the Institute for Nuclear Research of the Russian Academy of Sciences are divided into five groups based on what research they do, and they see a direct comparison of members of different groups as inadequate.”

The study was based on the citation data from the Google Scholar bibliographic database. To identify researcher types, the authors analyzed citation statistics for a large number of scientists, isolating and interpreting clusters of similar researchers.

Chebotarev and Vasilyev looked at the citation statistics for four groups of researchers returned by a Google Scholar search using the tags “Mathematics,” “Physics,” and “Psychology.” The first 515 and 556 search hits were considered in the case of physicists and psychologists, respectively. The authors studied two sets of mathematicians: the top 500 hits and hit Nos. 199-742. The four sets thus included frequently cited scientists from three disciplines indicating their general field of research in their profiles. Citation dynamics over each scientist’s career were examined using a range of indexes.

The authors initially identified three clusters, which they tentatively labeled as “leaders,” “successors,” and “toilers.” The leaders are experienced scientists widely recognized in their fields for research that has secured an annual citation count increase for them. The successors are young scientists who have more citations than toilers. The latter earn their high citation metrics owing to yearslong work, but they lack the illustrious scientific achievements.

Among the top 500 researchers indicating mathematics as their field of interest, 52 percent accounted for toilers, with successors and leaders making up 25.8 and 22.2 percent, respectively.

For physicists, the distribution was slightly different, with 48.5 percent of the set classified as toilers, 31.7 percent as successors, and 19.8 percent as leaders. That is, there were more successful young scientists, at the expense of leaders and toilers. This may be seen as a confirmation of the solitary nature of mathematical research, as compared with physics.

Finally, in the case of psychologists, toilers made up 47.7 percent of the set, with successors and leaders accounting for 18.3 and 34 percent. Comparing the distributions for the three disciplines investigated in the study, the authors conclude that there are more young achievers among those doing mathematical research.

A closer look enabled the authors to determine a more fine-grained cluster structure, which turned out to be remarkably similar for mathematicians and physicists. In particular, they identified a cluster of the youngest and most successful researchers, dubbed “precocious,” making up 4 percent of the mathematicians and 4.3 percent of the physicists in the set, along with the “youth” — successful researchers whose debuts were somewhat less dramatic: 29 and 31.7 percent of scientists doing math and physics research, respectively. Two further clusters were interpreted as recognized scientific authorities, or “luminaries,” and experienced researchers who have not seen an appreciable growth in the number of citations recently. Luminaries and the so-called inertia accounted for 52 and 15 percent of mathematicians and 50 and 14 percent of physicists, respectively.

There is an alternative way of clustering physicists, which recognizes a segment of researchers, who “caught the wave.” The authors suggest this might happen after joining major international research groups.

Among psychologists, 18.3 percent have been classified as precocious, though not as young as the physicists and mathematicians in the corresponding group. The most experienced and respected psychology researchers account for 22.5 percent, but there is no subdivision into luminaries and inertia, because those actively cited generally continue to be. Relatively young psychologists make up 59.2 percent of the set. The borders between clusters are relatively blurred in the case of psychology, which might be a feature of the humanities, according to the authors.

“Our pilot study showed even more similarity than we’d expected in how mathematicians and physicists are clustered,” says Chebotarev. “Whereas with psychology, things are noticeably different, yet the breakdown is slightly closer to math than physics. Perhaps, there is a certain connection between psychology and math after all, as some people say.”

“The next stage of this research features more disciplines. Hopefully, we will be ready to present the new results soon,” he concludes.

I think that they are attempting to create a new way of measuring scientific progress (scientometrics) by establishing a more representative means of measuring individual contributions based on the analysis they provide of the ways in which these ‘typologies’ are expressed across various disciplines.

For anyone who wants to investigate further, you will need to be able to read Russian. You can download the paper from here on MathNet.ru,.

Here’s my best attempt at a citation for the paper,

Making a typology of scientists on the basis of bibliometric data by I. Vasilyev, P. Yu. Chebotarev. Large-scale System Control (UBS), 2018, Issue 72, Pages 138–195 (Mi ubs948)

I’m glad to see this as there is a fair degree of dissatisfaction about the current measures for scientific progress used in any number of reports on the topic. As far as I can tell, this dissatisfaction is felt internationally.

Sound-absorbing nanofoam

In these increasingly noisy days (there’s construction going on around me), news of a cheaper, easier way to dull the noise is very attractive. From a June 25, 2018 Far Eastern Federal University (Russia) press release on EurekAlert,

The breakthrough material reduces a noise level by 100% more efficient comparing to standard analogs, cutting the level of noise transmission by 20-22 dB. The new foam reacts to sound waves not only of high but also of low frequencies, which can damage human health. A young scientist from the Far Eastern Federal University (FEFU) took part in the development.


Alexey Zavjalov, postdoc, researcher at the Academic Department of Nuclear Technologies School of Natural Science, FEFU, worked as a part of the international team of Russian and South Korean scientists under professor S.P. Bardakhanov. Alexey’s research performance led to the creation of nanofoam – the new noise-absorbing composite material. The results of the work are published in ‘Applied Acoustics’.

‘The problem of noise is the problem of modern technogenic civilization. In South Korea, cities are equipped with round-the-clock working stationary and mobile networks for noise levels monitoring. The urbanization level of such territorially small countries as South Korea is much higher than in Russia. However, in our country this problem is still crucial for big cities,’ – explained Alexey Zavjalov. – ‘The development of new noise-absorbing materials is especially interesting for the automotive industry. Modern people spend a lot of time driving cars and the noise level inside the vehicles’ directly determines the quality of life. For East Asian countries, the issue of noise control is relevant for high-speed rail lines.’ Porous materials are excellent sound absorbers but their noise-absorbing properties can be significantly enhanced by nanoporous grit injected into the foam structure and formed internal channels in it. Alexey Zavjalov has developed approaches for saturation of macroporous foam material with nanoporous grit.


Along with the rapid development of nanotechnology, there have been many attempts to mix nano- and microsized materials to create a modified material with enhanced strength, elastic, dynamical and vibrational properties. The acoustic parameters of such materials could not be fundamentally enhanced thus far.

Foam materials are most often used for soundproofing purposes. They provide the proper quality at a reasonable cost, but until today have been effective against high-frequency noise only. At the same time, low frequencies can be much more harmful to human health.

Infra- and low-frequency vibrations and noise (less than 0.4 kHz) are most harmful and dangerous for human health and life. Especially unfavorable is their long-lasting impact, since leads to serious diseases and pathologies. Complaints on such oppressions exceed 35% of the sum total of complaints on harmful environmental conditions.

The foam material, developed by Russian and Korean scientists, demonstrated promising results at medium frequencies and, therefore, more specialized low-frequency noise tests are needed.


The improved acoustic characteristics of the newest hybrid nanofoam were obtained by additional impregnation of the standard off-the-shelf sound-absorbing foam with porous granules of silica and magnetite nanoparticles. The porous foam was immersed in nanopowder suspensions in the liquid, subjected to ultrasonic treatment and dried.

The nanoparticles granules formed in the result can be compared structurally to a widely known class of materials – aerogel. It has not only excellent thermal insulation properties but also has a good noise-proof. However, aerogels are quite expensive and complex when used in structures. The new material, created according to the scheme developed by the FEFU researcher, is structurally similar to aerogel but is free of such shortcomings as a high price and engineering problems.


The mechanism of sound absorption of a new foam is based on the fact that its sound-absorbing surface is significantly scaled due to the presence of a large number of nanopores in the particles injected, as well as the location of these particles in the foam matrix in the form of distinct channels. Nanoparticles dissipate the energy of a sound wave transforming it into heat. The soundproof properties of the material increase.

Scientists found out that the composite structure is most effective for noise reduction. Thin layers of foam impregnated with nanoparticles are connected to each other in a “sandwich”-construction. This design significantly improves the soundproof properties of the resulting material. The outcome of the study also suggests that the more foamy material is impregnated with nanoparticles, the better it’s sound absorption is.

‘In some approximation, any material can be represented as a network of weights connected by springs. Such a mechanical system always has its own frequency bands, in which the oscillations propagate in the system relatively freely. There are also forbidden frequency bands in which the oscillations rapidly fade out in the system. To effectively extinguish the transmission of oscillations, including sound waves, the materials should be alternated in such a way that the fluctuations that propagate freely in the first material would be in the forbidden band for the second layer,’- commented Alexey Zavjalov. – ‘Of course, for our foam material, this idealization is too crude. However, it allows us to clearly illustrate the fundamentally conditioned necessity of creating a “sandwich” structure.’


The study showed the effectiveness of the method of foams impregnation with nanosilica or nanomagnetite, which form granules up to several hundred micrometers (in accordance with the pore sizes of the modified foam material) and having pores about 15 nm. This small addition provided a more complex and branched 3D network of nanochannels which led to an additional absorption of noise energy.

Due to the method used, the noise absorption efficiency was achieved in the range of 2.0-6.3 kHz and at lower frequencies 0.5-1.6 kHz. The degree of absorption was increased by 60-100% and the sound transmission was reduced by 20-22 dB, regardless of the type of nanofiller.

‘There is room to further improve the sound absorbing properties of the new material for medium and low frequencies using the” active control” strategy’. – Alexey Zavjalov comments on the plans for further development of such an important scientific topic. – ‘First of all, this refers to the materials obtained by using a magnetite nanopowder. Active noise protection systems have long been used in the world. The main idea is to detect the noise acoustic fields “online” and to generate sound waves in antiphase by means of loudspeakers. That allows achieving a significant reduction of noise in a given area. Concerning the nanofoam, it’s proposed to adapt this approach and to actively exert on a material saturated with granules of magnetite nanoparticles by magnetic fields. This will achieve even better noise reduction.’

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

Hybrid sound-absorbing foam materials with nanostructured grit-impregnated pores by S.P.Bardakhanov, C.M.Lee, V.N.Goverdovskiy, A.P.Zavjalov, K.V.Zobov, M.Chen, Z.H.Xu, I.K.Chakin, D.Yu.Trufanov. Applied Acoustics Volume 139, October 2018, Pages 69-74
https://doi.org/10.1016/j.apacoust.2018.04.024 Available online 23 April 2018.

This paper is behind a paywall.

If you have difficulty seeing the press release on EurekAlert, there is a June 26, 2018 news item on a Russian news site, RSF News and there is an edited version in a June 26, 2018 news item on Azonano.