Tag Archives: Germany

How do nanoscale crystals make volcanoes explode?

This research may have the answer as to why a supposedly peaceful volcano will suddenly explode violently. From a September 24, 2020 University of Bayreuth press release (also on EurekAlert),

Tiny crystals, ten thousand times thinner than a human hair, can cause explosive volcanic eruptions. This surprising connection has recently been discovered by a German-British research team led by Dr. Danilo Di Genova from the Bavarian Research Institute of Experimental Geochemistry & Geophysics (BGI) at the University of Bayreuth. The crystals increase the viscosity of the underground magma. As a result, a build-up of rising gases occurs. The continuously rising pressure finally discharges in massive eruptions. The scientists present the results of their nanogeoscientific research in the journal “Science Advances“.

“Exactly what causes the sudden and violent eruption of apparently peaceful volcanoes has always been a mystery in geology research. Nanogeoscience research has now allowed us to find an explanation. Tiny crystal grains containing mostly iron, silicon, and aluminium are the first link in a chain of cause and effect that can end in catastrophe for people living in the vicinity of a volcano. The most powerful volcanic eruption in human history was Mount Tambora in Indonesia in 1815”, says Dr. Danilo Di Genova. For the recently published study, he worked closely with scientists from the University of Bristol, the Clausthal University of Technology, and two European synchrotron radiation facilities.

Because of their diameter of a few nanometres, the crystals are also known as nanolites. Using spectroscopic and electron microscopy methods, the researchers have detected traces of these particles, invisible to the eye, in the ashes of active volcanoes. In the BGI’s laboratory, they were then able to describe these crystals and finally to demonstrate how they influence the properties of volcanic magma. The investigations focused on magma of low silicon oxide content cooling to form basalt on the earth’s surface after a volcanic eruption. Low silica magma is known for its low viscosity: It forms a thin lava that flows quickly and easily. The situation is different, however, if it contains a large number of nanolites. This makes the magma viscous – and far less permeable to gases rising from the earth’s interior. Instead of continuously escaping from the volcanic cone, the gases in the depths of the volcano become trapped in the hot magma. As a result, the magma is subjected to increasing pressure until it is finally ejected explosively from the volcano.

“Constant light plumes of smoke above a volcanic cone need not necessarily be interpreted as a sign of an imminent dangerous eruption. Conversely, however, the inactivity of apparently peaceful volcanoes can be deceptive. Rock analyses, written and archaeological sources suggest, for example, that people in the vicinity of Vesuvius were surprised by an extremely violent eruption of the volcano in 79 AD. Numerous fatalities and severe damage to buildings were the result”, says Di Genova. In his further research, the Bayreuth scientist hopes to use high-pressure facilites and computer simulation to model the geochemical processes that lead to such unexpected violent eruptions. The aim is to better understand these processes and thus also to reduce the risks for the population in the vicinity of volcanoes.

The researchers have included a nanocrystal image to illustrate their work,

Caption: A transmission electron microscopy image of a nano crystal (ca 25 nm in diameter) in a basaltic magma from Mt. Etna (Italy). The nano crystal is enriched in iron (Fe) and it was produced in a laboratory during at BGI. Credit Image: Nobuyoshi Miyajima.

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

In situ observation of nanolite growth in volcanic melt: A driving force for explosive eruptions by Danilo Di Genova, Richard A. Brooker, Heidy M. Mader, James W. E. Drewitt, Alessandro Longo, Joachim Deubener, Daniel R. Neuville, Sara Fanara, Olga Shebanova, Simone Anzellini, Fabio Arzilli, Emily C. Bamber, Louis Hennet, Giuseppe La Spina and Nobuyoshi Miyajima. Science Advances DOI: 10.1126/sciadv.abb0413 Vol. 6, no. 39, eabb0413 Published: 23 Sep 2020

This paper appears to be open access.

Technical University of Munich: embedded ethics approach for AI (artificial intelligence) and storing a tv series in synthetic DNA

I stumbled across two news bits of interest from the Technical University of Munich in one day (Sept. 1, 2020, I think). The topics: artificial intelligence (AI) and synthetic DNA (deoxyribonucleic acid).

Embedded ethics and artificial intelligence (AI)

An August 27, 2020 Technical University of Munich (TUM) press release (also on EurekAlert but published Sept. 1, 2020) features information about a proposal to embed ethicists in with AI development teams,

The increasing use of AI (artificial intelligence) in the development of new medical technologies demands greater attention to ethical aspects. An interdisciplinary team at the Technical University of Munich (TUM) advocates the integration of ethics from the very beginning of the development process of new technologies. Alena Buyx, Professor of Ethics in Medicine and Health Technologies, explains the embedded ethics approach.

Professor Buyx, the discussions surrounding a greater emphasis on ethics in AI research have greatly intensified in recent years, to the point where one might speak of “ethics hype” …

Prof. Buyx: … and many committees in Germany and around the world such as the German Ethics Council or the EU Commission High-Level Expert Group on Artificial Intelligence have responded. They are all in agreement: We need more ethics in the development of AI-based health technologies. But how do things look in practice for engineers and designers? Concrete solutions are still few and far between. In a joint pilot project with two Integrative Research Centers at TUM, the Munich School of Robotics and Machine Intelligence (MSRM) with its director, Prof. Sami Haddadin, and the Munich Center for Technology in Society (MCTS), with Prof. Ruth Müller, we want to try out the embedded ethics approach. We published the proposal in Nature Machine Intelligence at the end of July [2020].

What exactly is meant by the “embedded ethics approach”?

Prof.Buyx: The idea is to make ethics an integral part of the research process by integrating ethicists into the AI development team from day one. For example, they attend team meetings on a regular basis and create a sort of “ethical awareness” for certain issues. They also raise and analyze specific ethical and social issues.

Is there an example of this concept in practice?

Prof. Buyx: The Geriatronics Research Center, a flagship project of the MSRM in Garmisch-Partenkirchen, is developing robot assistants to enable people to live independently in old age. The center’s initiatives will include the construction of model apartments designed to try out residential concepts where seniors share their living space with robots. At a joint meeting with the participating engineers, it was noted that the idea of using an open concept layout everywhere in the units – with few doors or individual rooms – would give the robots considerable range of motion. With the seniors, however, this living concept could prove upsetting because they are used to having private spaces. At the outset, the engineers had not given explicit consideration to this aspect.

Prof.Buyx: The approach sounds promising. But how can we avoid “embedded ethics” from turning into an “ethics washing” exercise, offering companies a comforting sense of “being on the safe side” when developing new AI technologies?

That’s not something we can be certain of avoiding. The key is mutual openness and a willingness to listen, with the goal of finding a common language – and subsequently being prepared to effectively implement the ethical aspects. At TUM we are ideally positioned to achieve this. Prof. Sami Haddadin, the director of the MSRM, is also a member of the EU High-Level Group of Artificial Intelligence. In his research, he is guided by the concept of human centered engineering. Consequently, he has supported the idea of embedded ethics from the very beginning. But one thing is certain: Embedded ethics alone will not suddenly make AI “turn ethical”. Ultimately, that will require laws, codes of conduct and possibly state incentives.

Here’s a link to and a citation for the paper espousing the embedded ethics for AI development approach,

An embedded ethics approach for AI development by Stuart McLennan, Amelia Fiske, Leo Anthony Celi, Ruth Müller, Jan Harder, Konstantin Ritt, Sami Haddadin & Alena Buyx. Nature Machine Intelligence (2020) DOI: https://doi.org/10.1038/s42256-020-0214-1 Published 31 July 2020

This paper is behind a paywall.

Religion, ethics and and AI

For some reason embedded ethics and AI got me to thinking about Pope Francis and other religious leaders.

The Roman Catholic Church and AI

There was a recent announcement that the Roman Catholic Church will be working with MicroSoft and IBM on AI and ethics (from a February 28, 2020 article by Jen Copestake for British Broadcasting Corporation (BBC) news online (Note: A link has been removed),

Leaders from the two tech giants met senior church officials in Rome, and agreed to collaborate on “human-centred” ways of designing AI.

Microsoft president Brad Smith admitted some people may “think of us as strange bedfellows” at the signing event.

“But I think the world needs people from different places to come together,” he said.

The call was supported by Pope Francis, in his first detailed remarks about the impact of artificial intelligence on humanity.

The Rome Call for Ethics [sic] was co-signed by Mr Smith, IBM executive vice-president John Kelly and president of the Pontifical Academy for Life Archbishop Vincenzo Paglia.

It puts humans at the centre of new technologies, asking for AI to be designed with a focus on the good of the environment and “our common and shared home and of its human inhabitants”.

Framing the current era as a “renAIssance”, the speakers said the invention of artificial intelligence would be as significant to human development as the invention of the printing press or combustion engine.

UN Food and Agricultural Organization director Qu Dongyu and Italy’s technology minister Paola Pisano were also co-signatories.

Hannah Brockhaus’s February 28, 2020 article for the Catholic News Agency provides some details missing from the BBC report and I found it quite helpful when trying to understand the various pieces that make up this initiative,

The Pontifical Academy for Life signed Friday [February 28, 2020], alongside presidents of IBM and Microsoft, a call for ethical and responsible use of artificial intelligence technologies.

According to the document, “the sponsors of the call express their desire to work together, in this context and at a national and international level, to promote ‘algor-ethics.’”

“Algor-ethics,” according to the text, is the ethical use of artificial intelligence according to the principles of transparency, inclusion, responsibility, impartiality, reliability, security, and privacy.

The signing of the “Rome Call for AI Ethics [PDF]” took place as part of the 2020 assembly of the Pontifical Academy for Life, which was held Feb. 26-28 [2020] on the theme of artificial intelligence.

One part of the assembly was dedicated to private meetings of the academics of the Pontifical Academy for Life. The second was a workshop on AI and ethics that drew 356 participants from 41 countries.

On the morning of Feb. 28 [2020], a public event took place called “renAIssance. For a Humanistic Artificial Intelligence” and included the signing of the AI document by Microsoft President Brad Smith, and IBM Executive Vice-president John Kelly III.

The Director General of FAO, Dongyu Qu, and politician Paola Pisano, representing the Italian government, also signed.

The president of the European Parliament, David Sassoli, was also present Feb. 28.

Pope Francis canceled his scheduled appearance at the event due to feeling unwell. His prepared remarks were read by Archbishop Vincenzo Paglia, president of the Academy for Life.

You can find Pope Francis’s comments about the document here (if you’re not comfortable reading Italian, hopefully, the English translation which follows directly afterward will be helpful). The Pope’s AI initiative has a dedicated website, Rome Call for AI ethics, and while most of the material dates from the February 2020 announcement, they are keeping up a blog. It has two entries, one dated in May 2020 and another in September 2020.

Buddhism and AI

The Dalai Lama is well known for having an interest in science and having hosted scientists for various dialogues. So, I was able to track down a November 10, 2016 article by Ariel Conn for the futureoflife.org website, which features his insights on the matter,

The question of what it means and what it takes to feel needed is an important problem for ethicists and philosophers, but it may be just as important for AI researchers to consider. The Dalai Lama argues that lack of meaning and purpose in one’s work increases frustration and dissatisfaction among even those who are gainfully employed.

“The problem,” says the Dalai Lama, “is … the growing number of people who feel they are no longer useful, no longer needed, no longer one with their societies. … Feeling superfluous is a blow to the human spirit. It leads to social isolation and emotional pain, and creates the conditions for negative emotions to take root.”

If feeling needed and feeling useful are necessary for happiness, then AI researchers may face a conundrum. Many researchers hope that job loss due to artificial intelligence and automation could, in the end, provide people with more leisure time to pursue enjoyable activities. But if the key to happiness is feeling useful and needed, then a society without work could be just as emotionally challenging as today’s career-based societies, and possibly worse.

I also found a talk on the topic by The Venerable Tenzin Priyadarshi, first here’s a description from his bio at the Dalai Lama Center for Ethics and Transformative Values webspace on the Massachusetts Institute of Technology (MIT) website,

… an innovative thinker, philosopher, educator and a polymath monk. He is Director of the Ethics Initiative at the MIT Media Lab and President & CEO of The Dalai Lama Center for Ethics and Transformative Values at the Massachusetts Institute of Technology. Venerable Tenzin’s unusual background encompasses entering a Buddhist monastery at the age of ten and receiving graduate education at Harvard University with degrees ranging from Philosophy to Physics to International Relations. He is a Tribeca Disruptive Fellow and a Fellow at the Center for Advanced Study in Behavioral Sciences at Stanford University. Venerable Tenzin serves on the boards of a number of academic, humanitarian, and religious organizations. He is the recipient of several recognitions and awards and received Harvard’s Distinguished Alumni Honors for his visionary contributions to humanity.

He gave the 2018 Roger W. Heyns Lecture in Religion and Society at Stanford University on the topic, “Religious and Ethical Dimensions of Artificial Intelligence.” The video runs over one hour but he is a sprightly speaker (in comparison to other Buddhist speakers I’ve listened to over the years).

Judaism, Islam, and other Abrahamic faiths examine AI and ethics

I was delighted to find this January 30, 2020 Artificial Intelligence: Implications for Ethics and Religion event as it brought together a range of thinkers from various faiths and disciplines,

New technologies are transforming our world every day, and the pace of change is only accelerating.  In coming years, human beings will create machines capable of out-thinking us and potentially taking on such uniquely-human traits as empathy, ethical reasoning, perhaps even consciousness.  This will have profound implications for virtually every human activity, as well as the meaning we impart to life and creation themselves.  This conference will provide an introduction for non-specialists to Artificial Intelligence (AI):

What is it?  What can it do and be used for?  And what will be its implications for choice and free will; economics and worklife; surveillance economies and surveillance states; the changing nature of facts and truth; and the comparative intelligence and capabilities of humans and machines in the future? 

Leading practitioners, ethicists and theologians will provide cross-disciplinary and cross-denominational perspectives on such challenges as technology addiction, inherent biases and resulting inequalities, the ethics of creating destructive technologies and of turning decision-making over to machines from self-driving cars to “autonomous weapons” systems in warfare, and how we should treat the suffering of “feeling” machines.  The conference ultimately will address how we think about our place in the universe and what this means for both religious thought and theological institutions themselves.

UTS [Union Theological Seminary] is the oldest independent seminary in the United States and has long been known as a bastion of progressive Christian scholarship.  JTS [Jewish Theological Seminary] is one of the academic and spiritual centers of Conservative Judaism and a major center for academic scholarship in Jewish studies. The Riverside Church is an interdenominational, interracial, international, open, welcoming, and affirming church and congregation that has served as a focal point of global and national activism for peace and social justice since its inception and continues to serve God through word and public witness. The annual Greater Good Gathering, the following week at Columbia University’s School of International & Public Affairs, focuses on how technology is changing society, politics and the economy – part of a growing nationwide effort to advance conversations promoting the “greater good.”

They have embedded a video of the event (it runs a little over seven hours) on the January 30, 2020 Artificial Intelligence: Implications for Ethics and Religion event page. For anyone who finds that a daunting amount of information, you may want to check out the speaker list for ideas about who might be writing and thinking on this topic.

As for Islam, I did track down this November 29, 2018 article by Shahino Mah Abdullah, a fellow at the Institute of Advanced Islamic Studies (IAIS) Malaysia,

As the global community continues to work together on the ethics of AI, there are still vast opportunities to offer ethical inputs, including the ethical principles based on Islamic teachings.

This is in line with Islam’s encouragement for its believers to convey beneficial messages, including to share its ethical principles with society.

In Islam, ethics or akhlak (virtuous character traits) in Arabic, is sometimes employed interchangeably in the Arabic language with adab, which means the manner, attitude, behaviour, and etiquette of putting things in their proper places. Islamic ethics cover all the legal concepts ranging from syariah (Islamic law), fiqh ( jurisprudence), qanun (ordinance), and ‘urf (customary practices).

Adopting and applying moral values based on the Islamic ethical concept or applied Islamic ethics could be a way to address various issues in today’s societies.

At the same time, this approach is in line with the higher objectives of syariah (maqasid alsyariah) that is aimed at conserving human benefit by the protection of human values, including faith (hifz al-din), life (hifz alnafs), lineage (hifz al-nasl), intellect (hifz al-‘aql), and property (hifz al-mal). This approach could be very helpful to address contemporary issues, including those related to the rise of AI and intelligent robots.

..

Part of the difficulty with tracking down more about AI, ethics, and various religions is linguistic. I simply don’t have the language skills to search for the commentaries and, even in English, I may not have the best or most appropriate search terms.

Television (TV) episodes stored on DNA?

According to a Sept. 1, 2020 news item on Nanowerk, the first episode of a tv series, ‘Biohackers’ has been stored on synthetic DNA (deoxyribonucleic acid) by a researcher at TUM and colleagues at another institution,

The first episode of the newly released series “Biohackers” was stored in the form of synthetic DNA. This was made possible by the research of Prof. Reinhard Heckel of the Technical University of Munich (TUM) and his colleague Prof. Robert Grass of ETH Zürich.

They have developed a method that permits the stable storage of large quantities of data on DNA for over 1000 years.

A Sept. 1, 2020 TUM press release, which originated the news item, proceeds with more detail in an interview format,

Prof. Heckel, Biohackers is about a medical student seeking revenge on a professor with a dark past – and the manipulation of DNA with biotechnology tools. You were commissioned to store the series on DNA. How does that work?

First, I should mention that what we’re talking about is artificially generated – in other words, synthetic – DNA. DNA consists of four building blocks: the nucleotides adenine (A), thymine (T), guanine (G) and cytosine (C). Computer data, meanwhile, are coded as zeros and ones. The first episode of Biohackers consists of a sequence of around 600 million zeros and ones. To code the sequence 01 01 11 00 in DNA, for example, we decide which number combinations will correspond to which letters. For example: 00 is A, 01 is C, 10 is G and 11 is T. Our example then produces the DNA sequence CCTA. Using this principle of DNA data storage, we have stored the first episode of the series on DNA.

And to view the series – is it just a matter of “reverse translation” of the letters?

In a very simplified sense, you can visualize it like that. When writing, storing and reading the DNA, however, errors occur. If these errors are not corrected, the data stored on the DNA will be lost. To solve the problem, I have developed an algorithm based on channel coding. This method involves correcting errors that take place during information transfers. The underlying idea is to add redundancy to the data. Think of language: When we read or hear a word with missing or incorrect letters, the computing power of our brain is still capable of understanding the word. The algorithm follows the same principle: It encodes the data with sufficient redundancy to ensure that even highly inaccurate data can be restored later.

Channel coding is used in many fields, including in telecommunications. What challenges did you face when developing your solution?

The first challenge was to create an algorithm specifically geared to the errors that occur in DNA. The second one was to make the algorithm so efficient that the largest possible quantities of data can be stored on the smallest possible quantity of DNA, so that only the absolutely necessary amount of redundancy is added. We demonstrated that our algorithm is optimized in that sense.

DNA data storage is very expensive because of the complexity of DNA production as well as the reading process. What makes DNA an attractive storage medium despite these challenges?

First, DNA has a very high information density. This permits the storage of enormous data volumes in a minimal space. In the case of the TV series, we stored “only” 100 megabytes on a picogram – or a billionth of a gram of DNA. Theoretically, however, it would be possible to store up to 200 exabytes on one gram of DNA. And DNA lasts a long time. By comparison: If you never turned on your PC or wrote data to the hard disk it contains, the data would disappear after a couple of years. By contrast, DNA can remain stable for many thousands of years if it is packed right.

And the method you have developed also makes the DNA strands durable – practically indestructible.

My colleague Robert Grass was the first to develop a process for the “stable packing” of DNA strands by encapsulating them in nanometer-scale spheres made of silica glass. This ensures that the DNA is protected against mechanical influences. In a joint paper in 2015, we presented the first robust DNA data storage concept with our algorithm and the encapsulation process developed by Prof. Grass. Since then we have continuously improved our method. In our most recent publication in Nature Protocols of January 2020, we passed on what we have learned.

What are your next steps? Does data storage on DNA have a future?

We’re working on a way to make DNA data storage cheaper and faster. “Biohackers” was a milestone en route to commercialization. But we still have a long way to go. If this technology proves successful, big things will be possible. Entire libraries, all movies, photos, music and knowledge of every kind – provided it can be represented in the form of data – could be stored on DNA and would thus be available to humanity for eternity.

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

Reading and writing digital data in DNA by Linda C. Meiser, Philipp L. Antkowiak, Julian Koch, Weida D. Chen, A. Xavier Kohll, Wendelin J. Stark, Reinhard Heckel & Robert N. Grass. Nature Protocols volume 15, pages86–101(2020) Issue Date: January 2020 DOI: https://doi.org/10.1038/s41596-019-0244-5 Published [online] 29 November 2019

This paper is behind a paywall.

As for ‘Biohackers’, it’s a German science fiction television series and you can find out more about it here on the Internet Movie Database.

New design directions to increase variety, efficiency, selectivity and reliability for memristive devices

A May 11, 2020 news item on ScienceDaily provides a description of the current ‘memristor scene’ along with an announcement about a piece of recent research,

Scientists around the world are intensively working on memristive devices, which are capable in extremely low power operation and behave similarly to neurons in the brain. Researchers from the Jülich Aachen Research Alliance (JARA) and the German technology group Heraeus have now discovered how to systematically control the functional behaviour of these elements. The smallest differences in material composition are found crucial: differences so small that until now experts had failed to notice them. The researchers’ design directions could help to increase variety, efficiency, selectivity and reliability for memristive technology-based applications, for example for energy-efficient, non-volatile storage devices or neuro-inspired computers.

Memristors are considered a highly promising alternative to conventional nanoelectronic elements in computer Chips [sic]. Because of the advantageous functionalities, their development is being eagerly pursued by many companies and research institutions around the world. The Japanese corporation NEC installed already the first prototypes in space satellites back in 2017. Many other leading companies such as Hewlett Packard, Intel, IBM, and Samsung are working to bring innovative types of computer and storage devices based on memristive elements to market.

Fundamentally, memristors are simply “resistors with memory,” in which high resistance can be switched to low resistance and back again. This means in principle that the devices are adaptive, similar to a synapse in a biological nervous system. “Memristive elements are considered ideal candidates for neuro-inspired computers modelled on the brain, which are attracting a great deal of interest in connection with deep learning and artificial intelligence,” says Dr. Ilia Valov of the Peter Grünberg Institute (PGI-7) at Forschungszentrum Jülich.

In the latest issue of the open access journal Science Advances, he and his team describe how the switching and neuromorphic behaviour of memristive elements can be selectively controlled. According to their findings, the crucial factor is the purity of the switching oxide layer. “Depending on whether you use a material that is 99.999999 % pure, and whether you introduce one foreign atom into ten million atoms of pure material or into one hundred atoms, the properties of the memristive elements vary substantially” says Valov.

A May 11, 2020 Forschungszentrum Juelich press release (also on EurekAlert), which originated the news item, delves into the theme of increasing control over memristive systems,

This effect had so far been overlooked by experts. It can be used very specifically for designing memristive systems, in a similar way to doping semiconductors in information technology. “The introduction of foreign atoms allows us to control the solubility and transport properties of the thin oxide layers,” explains Dr. Christian Neumann of the technology group Heraeus. He has been contributing his materials expertise to the project ever since the initial idea was conceived in 2015.

“In recent years there has been remarkable progress in the development and use of memristive devices, however that progress has often been achieved on a purely empirical basis,” according to Valov. Using the insights that his team has gained, manufacturers could now methodically develop memristive elements selecting the functions they need. The higher the doping concentration, the slower the resistance of the elements changes as the number of incoming voltage pulses increases and decreases, and the more stable the resistance remains. “This means that we have found a way for designing types of artificial synapses with differing excitability,” explains Valov.

Design specification for artificial synapses

The brain’s ability to learn and retain information can largely be attributed to the fact that the connections between neurons are strengthened when they are frequently used. Memristive devices, of which there are different types such as electrochemical metallization cells (ECMs) or valence change memory cells (VCMs), behave similarly. When these components are used, the conductivity increases as the number of incoming voltage pulses increases. The changes can also be reversed by applying voltage pulses of the opposite polarity.

The JARA researchers conducted their systematic experiments on ECMs, which consist of a copper electrode, a platinum electrode, and a layer of silicon dioxide between them. Thanks to the cooperation with Heraeus researchers, the JARA scientists had access to different types of silicon dioxide: one with a purity of 99.999999 % – also called 8N silicon dioxide – and others containing 100 to 10,000 ppm (parts per million) of foreign atoms. The precisely doped glass used in their experiments was specially developed and manufactured by quartz glass specialist Heraeus Conamic, which also holds the patent for the procedure. Copper and protons acted as mobile doping agents, while aluminium and gallium were used as non-volatile doping.

Synapses, the connections between neurons, have the ability to transmit signals with varying degrees of strength when they are excited by a quick succession of electrical impulses. One effect of this repeated activity is to increase the concentration of calcium ions, with the result that more neurotransmitters are emitted. Depending on the activity, other effects cause long-term structural changes, which impact the strength of the transmission for several hours, or potentially even for the rest of the person’s life. Memristive elements allow the strength of the electrical transmission to be changed in a similar way to synaptic connections, by applying a voltage. In electrochemical metallization cells (ECMs), a metallic filament develops between the two metal electrodes, thus increasing conductivity. Applying voltage pulses with reversed polarity causes the filament to shrink again until the cell reaches its initial high resistance state. Copyright: Forschungszentrum Jülich / Tobias Schlößer

Record switching time confirms theory

Based on their series of experiments, the researchers were able to show that the ECMs’ switching times change as the amount of doping atoms changes. If the switching layer is made of 8N silicon dioxide, the memristive component switches in only 1.4 nanoseconds. To date, the fastest value ever measured for ECMs had been around 10 nanoseconds. By doping the oxide layer of the components with up to 10,000 ppm of foreign atoms, the switching time was prolonged into the range of milliseconds. “We can also theoretically explain our results. This is helping us to understand the physico-chemical processes on the nanoscale and apply this knowledge in the practice” says Valov. Based on generally applicable theoretical considerations, supported by experimental results, some also documented in the literature, he is convinced that the doping/impurity effect occurs and can be employed in all types memristive elements.

Top: In memristive elements (ECMs) with an undoped, high-purity switching layer of silicon oxide (SiO2), copper ions can move very fast. A filament of copper atoms forms correspondingly fast on the platinum electrode. This increases the total device conductivity respectively the capacity. Due to the high mobility of the ions, however, this filament is unstable at low forming voltages. Center: Gallium ions (Ga3+), which are introduced into the cell (non-volatile doping), bind copper ions (Cu2+) in the switching layer. The movement of the ions slows down, leading to lower switching times, but the filament, once formed remains longer stable. Bottom: Doping with aluminium ions (Al3+) slows down the process even more, since aluminium ions bind copper ions even stronger than gallium ions. Filament growth is even slower, while at the same time the stability of the filament is further increased. Depending on the chemical properties of the introduced doping elements, memristive cells – the artificial synapses – can be created with tailor-made switching and neuromorphic properties. Copyright: Forschungszentrum Jülich / Tobias Schloesser

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

Design of defect-chemical properties and device performance in memristive systems by M. Lübben, F. Cüppers, J. Mohr, M. von Witzleben, U. Breuer, R. Waser, C. Neumann, and I. Valov. Science Advances 08 May 2020: Vol. 6, no. 19, eaaz9079 DOI: 10.1126/sciadv.aaz9079

This paper is open access.

For anyone curious about the German technology group, Heraeus, there’s a fascinating history in its Wikipedia entry. The technology company was formally founded in 1851 but it can be traced back to the 17th century and the founding family’s apothecary.

You need a quantum mechanic for an atom-sized machine

This news comes from the National University of Singapore’s Centre for Quantum Technologies according to a May 4, 2020 news item on Nanowerk (Note: A link has been removed),

Here’s a new chapter in the story of the miniaturisation of machines: researchers in a laboratory in Singapore have shown that a single atom can function as either an engine or a fridge. Such a device could be engineered into future computers and fuel cells to control energy flows.

“Think about how your computer or laptop has a lot of things inside it that heat up. Today you cool that with a fan that blows air. In nanomachines or quantum computers, small devices that do cooling could be something useful,” says Dario Poletti from the Singapore University of Technology and Design (SUTD).

This work gives new insight into the mechanics of such devices. The work is a collaboration involving researchers at the Centre for Quantum Technologies (CQT) and Department of Physics at the National University of Singapore (NUS), SUTD and at the University of Augsburg in Germany. The results were published in the peer-reviewed journal npj Quantum Information (“Single-atom energy-conversion device with a quantum load”).

The researchers have included an exceptionally pretty illustration with the press release,

Caption: Experiments with a single-atom device help researchers understand what quantum effects come into play when machinery shrinks to the atomic scale. Credit: Aki Honda / Centre for Quantum Technologies, National University of Singapore

A May 4, 2020 National University of Singapore press release (also on EurekAlert), which originated the news item, delves further into the work,

Engines and refrigerators are both machines described by thermodynamics, a branch of science that tells us how energy moves within a system and how we can extract useful work. A classical engine turns energy into useful work. A refrigerator does work to transfer heat, reducing the local temperature. They are, in some sense, opposites.

People have made small heat engines before using a single atom, a single molecule and defects in diamond. A key difference about this device is that it shows quantumness in its action. “We want to understand how we can build thermodynamic devices with just a few atoms. The physics is not well understood so our work is important to know what is possible,” says Manas Mukherjee, a Principal Investigator at CQT, NUS, who led the experimental work.

The researchers studied the thermodynamics of a single barium atom. They devised a scheme in which lasers move one of the atom’s electrons between two energy levels as part of a cycle, causing some energy to be pushed into the atom’s vibrations. Like a car engine consumes petrol to both move pistons and charge up its battery, the atom uses energy from lasers as fuel to increase its vibrating motion. The atom’s vibrations act like a battery, storing energy that can be extracted later. Rearrange the cycle and the atom acts like a fridge, removing energy from the vibrations.

In either mode of operation, quantum effects show up in correlations between the atom’s electronic states and vibrations. “At this scale, the energy transfer between the engine and the load is a bit fuzzy. It is no longer possible to simply do work on the load, you are bound to transfer some heat,” says Poletti. He worked out the theory with collaborators Jiangbin Gong at NUS Physics and Peter Hänggi in Augsburg. The fuzziness makes the process less efficient, but the experimentalists could still make it work.

Mukherjee and colleagues Noah Van Horne, Dahyun Yum and Tarun Dutta used a barium atom from which an electron (a negative charge) is removed. This makes the atom positively charged, so it can be more easily held still inside a metal chamber by electrical fields. All other air is removed from around it. The atom is then zapped with lasers to move it through a four-stage cycle.

The researchers measured the atom’s vibration after applying 2 to 15 cycles. They repeated a given number of cycles up to 150 times, measuring on average how much vibrational energy was present at the end. They could see the vibrational energy increasing when the atom was zapped with an engine cycle, and decreasing when the zaps followed the fridge cycle.

Understanding the atom-sized machine involved both complicated calculations and observations. The team needed to track two thermodynamic quantities known as ergotropy, which is the energy that can be converted to useful work, and entropy, which is related to disorder in the system. Both ergotropy and entropy increase as the atom-machine runs. There’s still a simple way of looking at it, says first author and PhD student Van Horne, “Loosely speaking, we’ve designed a little machine that creates entropy as it is filled up with free energy, much like kids when they are given too much sugar.”

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

Single-atom energy-conversion device with a quantum load by Noah Van Horne, Dahyun Yum, Tarun Dutta, Peter Hänggi, Jiangbin Gong, Dario Poletti & Manas Mukherjee. npj Quantum Information volume 6, Article number: 37 (2020) Published: 01 May 2020

This paper is open access.

Trick your kidneys with sugar (molecules, that is)

A February 4, 2020 news item on Nanowerk announces research that makes it possible for kidneys to remove nanoparticles after they’ve been used in therapeutic remedies (Note: A link has been removed),

In the past decade nanomedicine has contributed to better detection and treatment of cancer. Nanoparticles are several 100 times smaller than the smallest grain of sand and can therefore easily travel in the blood stream to reach the tumor.

However, they are still too big to be removed by the kidneys. Since several doses of nanoparticles are necessary to treat a tumor, over time the nanoparticles can accumulate in the kidney and cause irreversible damage.

In a study published in the scientific journal Biomaterials (“Renal clearance of polymeric nanoparticles by mimicry of glycan surface of Viruses”), materials scientists at the University of Freiburg [Germany] led by Prof. Dr. Prasad Shastri from the Institute of Macromolecular Chemistry now present a natural solution to this problem: they built nanoparticles with the carbohydrate polysaccharides, which led to the excretion of the particles.

A February 4, 2020 University of Freiberg press release (also on EurekAlert), which originated the news item, expands on the theme,

In nature viruses such as the herpes simplex virus-1 and the cytomegalovirus, which are able to pass through the kidney filtration apparatus despite their large size compared to nanoparticles. Shastri and his team identified that both viruses presents sugar molecules on their surface. Inspired by this observation, the scientists engineered nanoparticles containing polysaccharides. These carbohydrates are frequently found in the human tissue environment. Using a real-time imaging technique, which they have established in their laboratory, the team investigated in a mouse model the fate of these nanoparticles. They observed that the polysaccharide-enriched nanoparticles readily pass through the kidney and are excreted with the urine within a few hours after intravenous administration. The decisive factor for the researchers was that the nanoparticles continued to act as intended and were still able to target tumors.

“The ability to combine tumor accumulation and kidney clearance in the same nanoparticle represents a tipping point in ensuring that nanomedicines can be safely administered” says Shastri. “Our nature-inspired approach enabled us to trick the kidney environment to let nanoparticles pass through” adds Dr. Melika Sarem who was a co-author of the study.

Prasad Shastri is Professor of Biofunctional Macromolecular Chemistry at the Institute for Macromolecular Chemistry and Professor of Cell Signalling Environments in the Excellence Cluster BIOSS Centre for Biological Signalling Studies and at the University of Freiburg.

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

Renal clearance of polymeric nanoparticles by mimicry of glycan surface of viruses by Pradeep P.Wyss, Surya P.Lamichhane, Ahmed Abed, Daniel Vonwil, Oliver Kretz, Tobias B. Huber, Melika Sarema, V. Prasad Shastri. Biomaterials Volume 230, February 2020, 119643 DOI: https://doi.org/10.1016/j.biomaterials.2019.119643 First published online November 23, 2019

This paper is behind a paywall.

Of puke, CRISPR, fruit flies, and monarch butterflies

I’ve never seen an educational institution use a somewhat vulgar slang term such as ‘puke’ before. Especially not in a news release. You’ll find that elsewhere online ‘puke’ has been replaced, in the headline, with the more socially acceptable ‘vomit’.

Since I wanted to catch this historic moment amid concerns that the original version of the news release will disappear, I’m including the entire news release as i saw it on EurekAlert.com (from an October 2, 2019 University of California at Berkeley news release),

News Release 2-Oct-2019

CRISPRed fruit flies mimic monarch butterfly — and could make you puke
Scientists recreate in flies the mutations that let monarch butterfly eat toxic milkweed with impunity

University of California – Berkeley

The fruit flies in Noah Whiteman’s lab may be hazardous to your health.

Whiteman and his University of California, Berkeley, colleagues have turned perfectly palatable fruit flies — palatable, at least, to frogs and birds — into potentially poisonous prey that may cause anything that eats them to puke. In large enough quantities, the flies likely would make a human puke, too, much like the emetic effect of ipecac syrup.

That’s because the team genetically engineered the flies, using CRISPR-Cas9 gene editing, to be able to eat milkweed without dying and to sequester its toxins, just as America’s most beloved butterfly, the monarch, does to deter predators.

This is the first time anyone has recreated in a multicellular organism a set of evolutionary mutations leading to a totally new adaptation to the environment — in this case, a new diet and new way of deterring predators.

Like monarch caterpillars, the CRISPRed fruit fly maggots thrive on milkweed, which contains toxins that kill most other animals, humans included. The maggots store the toxins in their bodies and retain them through metamorphosis, after they turn into adult flies, which means the adult “monarch flies” could also make animals upchuck.

The team achieved this feat by making three CRISPR edits in a single gene: modifications identical to the genetic mutations that allow monarch butterflies to dine on milkweed and sequester its poison. These mutations in the monarch have allowed it to eat common poisonous plants other insects could not and are key to the butterfly’s thriving presence throughout North and Central America.

Flies with the triple genetic mutation proved to be 1,000 times less sensitive to milkweed toxin than the wild fruit fly, Drosophila melanogaster.

Whiteman and his colleagues will describe their experiment in the Oct. 2 [2019] issue of the journal Nature.

Monarch flies

The UC Berkeley researchers created these monarch flies to establish, beyond a shadow of a doubt, which genetic changes in the genome of monarch butterflies were necessary to allow them to eat milkweed with impunity. They found, surprisingly, that only three single-nucleotide substitutions in one gene are sufficient to give fruit flies the same toxin resistance as monarchs.

“All we did was change three sites, and we made these superflies,” said Whiteman, an associate professor of integrative biology. “But to me, the most amazing thing is that we were able to test evolutionary hypotheses in a way that has never been possible outside of cell lines. It would have been difficult to discover this without having the ability to create mutations with CRISPR.”

Whiteman’s team also showed that 20 other insect groups able to eat milkweed and related toxic plants – including moths, beetles, wasps, flies, aphids, a weevil and a true bug, most of which sport the color orange to warn away predators – independently evolved mutations in one, two or three of the same amino acid positions to overcome, to varying degrees, the toxic effects of these plant poisons.

In fact, his team reconstructed the one, two or three mutations that led to each of the four butterfly and moth lineages, each mutation conferring some resistance to the toxin. All three mutations were necessary to make the monarch butterfly the king of milkweed.
Resistance to milkweed toxin comes at a cost, however. Monarch flies are not as quick to recover from upsets, such as being shaken — a test known as “bang” sensitivity.

“This shows there is a cost to mutations, in terms of recovery of the nervous system and probably other things we don’t know about,” Whiteman said. “But the benefit of being able to escape a predator is so high … if it’s death or toxins, toxins will win, even if there is a cost.”

Plant vs. insect

Whiteman is interested in the evolutionary battle between plants and parasites and was intrigued by the evolutionary adaptations that allowed the monarch to beat the milkweed’s toxic defense. He also wanted to know whether other insects that are resistant — though all less resistant than the monarch — use similar tricks to disable the toxin.

“Since plants and animals first invaded land 400 million years ago, this coevolutionary arms race is thought to have given rise to a lot of the plant and animal diversity that we see, because most animals are insects, and most insects are herbivorous: they eat plants,” he said.

Milkweeds and a variety of other plants, including foxglove, the source of digitoxin and digoxin, contain related toxins — called cardiac glycosides — that can kill an elephant and any creature with a beating heart. Foxglove’s effect on the heart is the reason that an extract of the plant, in the genus Digitalis, has been used for centuries to treat heart conditions, and why digoxin and digitoxin are used today to treat congestive heart failure.

These plants’ bitterness alone is enough to deter most animals, but a small minority of insects, including the monarch (Danaus plexippus) and its relative, the queen butterfly (Danaus gilippus), have learned to love milkweed and use it to repel predators.

Whiteman noted that the monarch is a tropical lineage that invaded North America after the last ice age, in part enabled by the three mutations that allowed it to eat a poisonous plant other animals could not, giving it a survival edge and a natural defense against predators.

“The monarch resists the toxin the best of all the insects, and it has the biggest population size of any of them; it’s all over the world,” he said.

The new paper reveals that the mutations had to occur in the right sequence, or else the flies would never have survived the three separate mutational events.

Thwarting the sodium pump

The poisons in these plants, most of them a type of cardenolide, interfere with the sodium/potassium pump (Na+/K+-ATPase) that most of the body’s cells use to move sodium ions out and potassium ions in. The pump creates an ion imbalance that the cell uses to its favor. Nerve cells, for example, transmit signals along their elongated cell bodies, or axons, by opening sodium and potassium gates in a wave that moves down the axon, allowing ions to flow in and out to equilibrate the imbalance. After the wave passes, the sodium pump re-establishes the ionic imbalance.

Digitoxin, from foxglove, and ouabain, the main toxin in milkweed, block the pump and prevent the cell from establishing the sodium/potassium gradient. This throws the ion concentration in the cell out of whack, causing all sorts of problems. In animals with hearts, like birds and humans, heart cells begin to beat so strongly that the heart fails; the result is death by cardiac arrest.

Scientists have known for decades how these toxins interact with the sodium pump: they bind the part of the pump protein that sticks out through the cell membrane, clogging the channel. They’ve even identified two specific amino acid changes or mutations in the protein pump that monarchs and the other insects evolved to prevent the toxin from binding.

But Whiteman and his colleagues weren’t satisfied with this just so explanation: that insects coincidentally developed the same two identical mutations in the sodium pump 14 separate times, end of story. With the advent of CRISPR-Cas9 gene editing in 2012, coinvented by UC Berkeley’s Jennifer Doudna, Whiteman and colleagues Anurag Agrawal of Cornell University and Susanne Dobler of the University of Hamburg in Germany applied to the Templeton Foundation for a grant to recreate these mutations in fruit flies and to see if they could make the flies immune to the toxic effects of cardenolides.

Seven years, many failed attempts and one new grant from the National Institutes of Health later, along with the dedicated CRISPR work of GenetiVision of Houston, Texas, they finally achieved their goal. In the process, they discovered a third critical, compensatory mutation in the sodium pump that had to occur before the last and most potent resistance mutation would stick. Without this compensatory mutation, the maggots died.

Their detective work required inserting single, double and triple mutations into the fruit fly’s own sodium pump gene, in various orders, to assess which ones were necessary. Insects having only one of the two known amino acid changes in the sodium pump gene were best at resisting the plant poisons, but they also had serious side effects — nervous system problems — consistent with the fact that sodium pump mutations in humans are often associated with seizures. However, the third, compensatory mutation somehow reduces the negative effects of the other two mutations.

“One substitution that evolved confers weak resistance, but it is always present and allows for substitutions that are going to confer the most resistance,” said postdoctoral fellow Marianna Karageorgi, a geneticist and evolutionary biologist. “This substitution in the insect unlocks the resistance substitutions, reducing the neurological costs of resistance. Because this trait has evolved so many times, we have also shown that this is not random.”

The fact that one compensatory mutation is required before insects with the most resistant mutation could survive placed a constraint on how insects could evolve toxin resistance, explaining why all 21 lineages converged on the same solution, Whiteman said. In other situations, such as where the protein involved is not so critical to survival, animals might find different solutions.

“This helps answer the question, ‘Why does convergence evolve sometimes, but not other times?'” Whiteman said. “Maybe the constraints vary. That’s a simple answer, but if you think about it, these three mutations turned a Drosophila protein into a monarch one, with respect to cardenolide resistance. That’s kind of remarkable.”

###

The research was funded by the Templeton Foundation and the National Institutes of Health. Co-authors with Whiteman and Agrawal are co-first authors Marianthi Karageorgi of UC Berkeley and Simon Groen, now at New York University; Fidan Sumbul and Felix Rico of Aix-Marseille Université in France; Julianne Pelaez, Kirsten Verster, Jessica Aguilar, Susan Bernstein, Teruyuki Matsunaga and Michael Astourian of UC Berkeley; Amy Hastings of Cornell; and Susanne Dobler of Universität Hamburg in Germany.

Robert Sanders’ Oct. 2, 2019′ news release for the University of California at Berkeley (it’s also been republished as an Oct. 2, 2019 news item on ScienceDaily) has had its headline changed to ‘vomit’ but you’ll find the more vulgar word remains in two locations of the second paragraph of the revised new release.

If you have time, go to the news release on the University of California at Berkeley website just to admire the images that have been embedded in the news release. Here’s one,

Caption: A Drosophila melanogaster “monarch fly” with mutations introduced by CRISPR-Cas9 genome editing (V111, S119 and H122) to the sodium potassium pump, on a wing of a monarch butterfly (Danaus plexippus). Credit & Ccpyright: Julianne Pelaez

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

Genome editing retraces the evolution of toxin resistance in the monarch butterfly by Marianthi Karageorgi, Simon C. Groen, Fidan Sumbul, Julianne N. Pelaez, Kirsten I. Verster, Jessica M. Aguilar, Amy P. Hastings, Susan L. Bernstein, Teruyuki Matsunaga, Michael Astourian, Geno Guerra, Felix Rico, Susanne Dobler, Anurag A. Agrawal & Noah K. Whiteman. Nature (2019) DOI: https://doi.org/10.1038/s41586-019-1610-8 Published 02 October 2019

This paper is behind a paywall.

Words about a word

I’m glad they changed the headline and substituted vomit for puke. I think we need vulgar and/or taboo words to release anger or disgust or other difficult emotions. Incorporating those words into standard language deprives them of that power.

The last word: Genetivision

The company mentioned in the new release, Genetivision, is the place to go for transgenic flies. Here’s a sampling from the their Testimonials webpage,

GenetiVision‘s service has been excellent in the quality and price. The timeliness of its international service has been a big plus. We are very happy with its consistent service and the flies it generates.”
Kwang-Wook Choi, Ph.D.
Department of Biological Sciences
Korea Advanced Institute of Science and Technology


“We couldn’t be happier with GenetiVision. Great prices on both standard P and PhiC31 transgenics, quick turnaround time, and we’re still batting 1000 with transformant success. We used to do our own injections but your service makes it both faster and more cost-effective. Thanks for your service!”
Thomas Neufeld, Ph.D.
Department of Genetics, Cell Biology and Development
University of Minnesota

You can find out more here at the Genetivision website.

Better anti-parasitic medicine delivery with chitosan-based nanocapsules

I mage: The common liver fluke which can cause fascioliasis. Credit: Wikimedia creative commons Courtesy: Leeds University

It looks like a pair of lips to me but, according to a December 12, 2018 news item on Nanowerk, this liver fluke heralds a flatworm infection is a serious health problem,

An international team, led by Professor Francisco Goycoolea from the University of Leeds [UK] and Dr Claudio Salomon from the Universidad Nacional de Rosario, Argentina, and in collaboration with colleagues at the University of Münster, Germany, have developed a novel pharmaceutical formulation to administer triclabendazole – an anti-parasitic drug used to treat a type of flatworm infection – in billions of tiny capsules.

The World Health Organisation estimates that 2.4 million people are infected with fascioliasis, the disease caused by flatworms and treated with triclabendazole.

A December 12, 2018 University of Leeds  press release (also on EurekAlert), which originated the news item,

Anti-parasitic drugs do not become effective until they dissolve and are absorbed. Traditionally, these medicines are highly insoluble and this limits their therapeutic effect.
In a bid to overcome this limitation and accomplish the new formulation, the team used “soft” nanotechnology and nanomedicine approaches, which utilises the self-assembly properties of organic nanostructures and uses techniques in which components, such as polymers and surfactants in solution, play key roles.

Their formulation produces capsules that are less than one micron in size – the diameter of a human hair is roughly 75 microns. These tiny capsules are loaded with triclabendazole and then bundled together to deliver the required dose.

The team used chitosan, a naturally-occurring sugar polymer found in the exoskeleton of shellfish and the cell walls of certain fungi, to coat the oil-core of capsules and bind the drug together, while stabilising the capsule and helping to preserve it.
In its nanocapsule form, the drug would be 100 times more soluble than its current tablet form.

Professor Goycoolea, from the School of Food Science and Nutrition at Leeds, said: “Solubility is critical challenge for effective anti-parasite medicine. We looked to tackle this problem at the particle level. Triclabendazole taken as a dose made up of billions of tiny capsules would mean the medicine would be more efficiently and quickly absorbed

“Through the use of nanocapsules and nanoemulsions, drug efficiency can be enhanced and new solutions can be considered for the best ways to target medicine delivery.”
Dr Salomon said: “To date, this is the first report on triclabendazole nanoencapsulation and we believe this type of formulation could be applied to other anti-parasitic drugs as well. But more research is needed to ensure this new pharmaceutical formulation of the drug does not diminish the anti-parasitic effect. Our ongoing research is working to answer this very question.”

Although there have been cases of fascioliasis in more than 70 countries worldwide, with increasing reports from Europe and the Americas, it is considered a neglected disease, as it does not receive much attention and often goes untreated.
Symptoms of the disease when it reaches the chronic phase include intermittent pain, jaundice and anaemia. Patients can also experience hardening of the liver in the case of long-term inflammation.

Because of the highly insoluble nature of anti-parasitic drugs, they need to be administered in very high dosages to ensure enough of the active ingredient is absorbed. This is particularly problematic when treating children for parasites. Tablets needs to be divided into smaller pieces to adjust the dosage and make swallowing easier, but this can cause side effects due to incorrect dosage.

The team’s technique to formulate triclabendazole into nanocapsules, published today [Dec. 12, 2018] in the journal PLOS ONE, would also allow for lower doses to be administered. s

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

Chitosan-based nanodelivery systems applied to the development of novel triclabendazole formulations by Daniel Real, Stefan Hoffmann, Darío Leonardi, Claudio Salomon, Francisco M. Goycoolea. PLOS DOI https://doi.org/10.1371/journal.pone.0207625 Published: December 12, 2018

This paper is open access. BTW, I loved the title for the press release (Helping the anti-parasitic medicine go down) for its reference to the song, A spoonful of sugar helps the medicine go down, in the 1964 film musical, Mary Poppins, and the shout out for the sort of sequel, Mary Poppins Returns, released on Dec. 19, 2018.

Membrane stretching as a new transport mechanism for nanomaterials

This work comes from Catalonia, Spain by way of a collaboration between Chinese, German, and, of course, Spanish scientists. From a December 12, 2018 Universitat Rovira i Virgili press release (also on EurekAlert),

Increasing awareness of bioeffects and toxicity of nanomaterials interacting with cells puts in focus the mechanisms by which nanomaterials can cross lipid membranes. Apart from well-discussed energy-dependent endocytosis for large objects and passive diffusion through membranes by solute molecules, there can exist other transport mechanisms based on physical principles. Based on this hypothesis, the team of theoretical physics at Universitat Rovira i Virgili in Tarragona, led by Dr. Vladimir Baulin, designed a research project to investigate the interaction between nanotube and lipid membranes. In computer simulations, the researchers studied what they call a “model bilayer”, composed only by one type of lipids. Based on their calculations, the team of Dr. Baulin observed that ultra -short nanotube (10nm length) can insert perpendicularly to the lipid bilayer core.

They observed that these nanotubes stay trapped in the cell membrane, as commonly accepted by the scientific community. But a surprise appears when they stretched their model cell membrane, then inserted nanotubes which were trapped in the bilayer, suddenly started to escape from the bilayer on both sides. This means that it is possible to control the transport of nanomaterial across a cell membrane by tuning the membrane tension.

This is where Dr. Baulin contacted Dr. Jean-Baptiste Fleury at the Saarland University (Germany) to confirm this mechanism and to study experimentally this tension-mediated transport phenomena. Dr. Fleury and his team, designed a microfluidic experiment with a well-controlled phospholipid bilayer, an experimental model for cell membranes and added ultra-small carbon nanotubes (10nm in length) in solution. The nanotubes had an adsorbed lipid monolayer that guarantees their stable dispersion and prevent their clustering. Using a combination of optical fluorescent microscopy and electrophysiological measurements, the team of Dr. Fleury could follow individual nanotube crossing a bilayer and unravel their pathway on a molecular level. And as predicted by the simulations, they observed that nanotubes inserted into the bilayer by dissolving their lipid coating into the artificial membrane. When a tension of 4mN/m was applied to the bilayer, nanotubes spontaneously escaped the bilayer just in few milliseconds, while at lower tensions nanotubes remain trapped inside the membrane.

This discovery of translocation of tiny nanotubes through barriers protecting cells, i.e. lipid bilayer, may raise concerns about safety of nanomaterials for public health and suggest new mechanical mechanisms to control the drug delivery.

Caption: Nanotubes trapped inside the membrane. Credit: © URV

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

Tension-Induced Translocation of an Ultrashort Carbon Nanotube through a Phospholipid Bilayer by Yachong Guo, Marco Werner, Ralf Seemann, Vladimir A. Baulin, and Jean-Baptiste Fleury. ACS Nano, Article ASAP DOI: 10.1021/acsnano.8b04657 Publication Date (Web): November 19, 2018

Copyright © 2018 American Chemical Society

This paper is behind a paywall.

Artificial synapse courtesy of nanowires

It looks like a popsicle to me,

Caption: Image captured by an electron microscope of a single nanowire memristor (highlighted in colour to distinguish it from other nanowires in the background image). Blue: silver electrode, orange: nanowire, yellow: platinum electrode. Blue bubbles are dispersed over the nanowire. They are made up of silver ions and form a bridge between the electrodes which increases the resistance. Credit: Forschungszentrum Jülich

Not a popsicle but a representation of a device (memristor) scientists claim mimics a biological nerve cell according to a December 5, 2018 news item on ScienceDaily,

Scientists from Jülich [Germany] together with colleagues from Aachen [Germany] and Turin [Italy] have produced a memristive element made from nanowires that functions in much the same way as a biological nerve cell. The component is able to both save and process information, as well as receive numerous signals in parallel. The resistive switching cell made from oxide crystal nanowires is thus proving to be the ideal candidate for use in building bioinspired “neuromorphic” processors, able to take over the diverse functions of biological synapses and neurons.

A Dec. 5, 2018 Forschungszentrum Jülich press release (also on EurekAlert), which originated the news item, provides more details,

Computers have learned a lot in recent years. Thanks to rapid progress in artificial intelligence they are now able to drive cars, translate texts, defeat world champions at chess, and much more besides. In doing so, one of the greatest challenges lies in the attempt to artificially reproduce the signal processing in the human brain. In neural networks, data are stored and processed to a high degree in parallel. Traditional computers on the other hand rapidly work through tasks in succession and clearly distinguish between the storing and processing of information. As a rule, neural networks can only be simulated in a very cumbersome and inefficient way using conventional hardware.

Systems with neuromorphic chips that imitate the way the human brain works offer significant advantages. Experts in the field describe this type of bioinspired computer as being able to work in a decentralised way, having at its disposal a multitude of processors, which, like neurons in the brain, are connected to each other by networks. If a processor breaks down, another can take over its function. What is more, just like in the brain, where practice leads to improved signal transfer, a bioinspired processor should have the capacity to learn.

“With today’s semiconductor technology, these functions are to some extent already achievable. These systems are however suitable for particular applications and require a lot of space and energy,” says Dr. Ilia Valov from Forschungszentrum Jülich. “Our nanowire devices made from zinc oxide crystals can inherently process and even store information, as well as being extremely small and energy efficient,” explains the researcher from Jülich’s Peter Grünberg Institute.

For years memristive cells have been ascribed the best chances of being capable of taking over the function of neurons and synapses in bioinspired computers. They alter their electrical resistance depending on the intensity and direction of the electric current flowing through them. In contrast to conventional transistors, their last resistance value remains intact even when the electric current is switched off. Memristors are thus fundamentally capable of learning.

In order to create these properties, scientists at Forschungszentrum Jülich and RWTH Aachen University used a single zinc oxide nanowire, produced by their colleagues from the polytechnic university in Turin. Measuring approximately one ten-thousandth of a millimeter in size, this type of nanowire is over a thousand times thinner than a human hair. The resulting memristive component not only takes up a tiny amount of space, but also is able to switch much faster than flash memory.

Nanowires offer promising novel physical properties compared to other solids and are used among other things in the development of new types of solar cells, sensors, batteries and computer chips. Their manufacture is comparatively simple. Nanowires result from the evaporation deposition of specified materials onto a suitable substrate, where they practically grow of their own accord.

In order to create a functioning cell, both ends of the nanowire must be attached to suitable metals, in this case platinum and silver. The metals function as electrodes, and in addition, release ions triggered by an appropriate electric current. The metal ions are able to spread over the surface of the wire and build a bridge to alter its conductivity.

Components made from single nanowires are, however, still too isolated to be of practical use in chips. Consequently, the next step being planned by the Jülich and Turin researchers is to produce and study a memristive element, composed of a larger, relatively easy to generate group of several hundred nanowires offering more exciting functionalities.

The Italians have also written about the work in a December 4, 2018 news item for the Polytecnico di Torino’s inhouse magazine, PoliFlash’. I like the image they’ve used better as it offers a bit more detail and looks less like a popsicle. First, the image,

Courtesy: Polytecnico di Torino

Now, the news item, which includes some historical information about the memristor (Note: There is some repetition and links have been removed),

Emulating and understanding the human brain is one of the most important challenges for modern technology: on the one hand, the ability to artificially reproduce the processing of brain signals is one of the cornerstones for the development of artificial intelligence, while on the other the understanding of the cognitive processes at the base of the human mind is still far away.

And the research published in the prestigious journal Nature Communications by Gianluca Milano and Carlo Ricciardi, PhD student and professor, respectively, of the Applied Science and Technology Department of the Politecnico di Torino, represents a step forward in these directions. In fact, the study entitled “Self-limited single nanowire systems combining all-in-one memristive and neuromorphic functionalities” shows how it is possible to artificially emulate the activity of synapses, i.e. the connections between neurons that regulate the learning processes in our brain, in a single “nanowire” with a diameter thousands of times smaller than that of a hair.

It is a crystalline nanowire that takes the “memristor”, the electronic device able to artificially reproduce the functions of biological synapses, to a more performing level. Thanks to the use of nanotechnologies, which allow the manipulation of matter at the atomic level, it was for the first time possible to combine into one single device the synaptic functions that were individually emulated through specific devices. For this reason, the nanowire allows an extreme miniaturisation of the “memristor”, significantly reducing the complexity and energy consumption of the electronic circuits necessary for the implementation of learning algorithms.

Starting from the theorisation of the “memristor” in 1971 by Prof. Leon Chua – now visiting professor at the Politecnico di Torino, who was conferred an honorary degree by the University in 2015 – this new technology will not only allow smaller and more performing devices to be created for the implementation of increasingly “intelligent” computers, but is also a significant step forward for the emulation and understanding of the functioning of the brain.

“The nanowire memristor – said Carlo Ricciardirepresents a model system for the study of physical and electrochemical phenomena that govern biological synapses at the nanoscale. The work is the result of the collaboration between our research team and the RWTH University of Aachen in Germany, supported by INRiM, the National Institute of Metrological Research, and IIT, the Italian Institute of Technology.”

h.t for the Italian info. to Nanowerk’s Dec. 10, 2018 news item.

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

Self-limited single nanowire systems combining all-in-one memristive and neuromorphic functionalities by Gianluca Milano, Michael Luebben, Zheng Ma, Rafal Dunin-Borkowski, Luca Boarino, Candido F. Pirri, Rainer Waser, Carlo Ricciardi, & Ilia Valov. Nature Communicationsvolume 9, Article number: 5151 (2018) DOI: https://doi.org/10.1038/s41467-018-07330-7 Published: 04 December 2018

This paper is open access.

Just use the search term “memristor” in the blog search engine if you’re curious about the multitudinous number of postings on the topic here.

Defending nanoelectronics from cyber attacks

There’s a new program at the University of Stuttgart (Germany) and their call for projects was recently announced. First, here’s a description of the program in a May 30, 2019 news item on Nanowerk,

Today’s societies critically depend on electronic systems. Past spectacular cyber-attacks have clearly demonstrated the vulnerability of existing systems and the need to prevent such attacks in the future. The majority of available cyber-defenses concentrate on protecting the software part of electronic systems or their communication interfaces.

However, manufacturing technology advancements and the increasing hardware complexity provide a large number of challenges so that the focus of attackers has shifted towards the hardware level. We saw already evidence for powerful and successful hardware-level attacks, including Rowhammer, Meltdown and Spectre.

These attacks happened on products built using state-of-the-art microelectronic technology, however, we are facing completely new security challenges due to the ongoing transition to radically new types of nanoelectronic devices, such as memristors, spintronics, or carbon nanotubes and graphene based transistors.

The use of such emerging nanotechnologies is inevitable to address the key challenges related to energy efficiency, computing power and performance. Therefore, the entire industry, are switching to emerging nano-electronics alongside scaled CMOS technologies in heterogeneous integrated systems.

These technologies come with new properties and also facilitate the development of radically different computer architectures. The new technologies and architectures provide new opportunities for achieving security targets, but also raise questions about their vulnerabilities to new types of hardware attacks.

A May 28, 2019 University of Stuttgart press release provides more information about the program and the call for projects,

Whether it’s cars, industrial plants or the government network, spectacular cyber attacks over the past few months have shown how vulnerable modern electronic systems are. The aim of the new Priority Program “Nano Security”, which is coordinated by the University of Stuttgart, is protecting you and preventing the cyber attacks of the future. The program, which is funded by the German Research Foundation (DFG), emphasizes making the hardware into a reliable foundation of a system or a layer of security.

The challenges of nanoelectronics

Completely new challenges also emerge as a result of the switch to radically new nanoelectronic components, which for example are used to master the challenges of the future in terms of energy efficiency, computing power and secure data transmission. For example, memristors (components which are not just used to store information but also function as logic modules), the spintronics, which exploit quantum-mechanical effects, or carbon nanotubes.

The new technologies, as well as the fundamentally different computer architecture associated with them, offer new opportunities for cryptographic primitives in order to achieve an even more secure data transmission. However, they also raise questions about their vulnerability to new types of hardware attacks.

The problem is part of the solution

In this context, a better understanding should be developed of what consequences the new nanoelectronic technologies have for the security of circuits and systems as part of the new Priority Program. Here, the hardware is not just thought of as part of the problem but also as an important and necessary part of the solution to security problems. The starting points here for example are the hardware-based generation of cryptographic keys, the secure storage and processing of sensitive data, and the isolation of system components which is guaranteed by the hardware. Lastly, it should be ensured that an attack cannot be spread further by the system.

In this process, the scientists want to assess the possible security risks and weaknesses which stem from the new type of nanoelectronics. Furthermore, they want to develop innovative approaches for system security which are based on nanoelectronics as a security anchor.

The Priority Program promotes cooperation between scientists, who develop innovative security solutions for the computer systems of the future on different levels of abstraction. Likewise, it makes methods available to system designers to keep ahead in the race between attackers and security measures over the next few decades.

The call has started

The DFG Priority Program “Nano Security. From Nano-Electronics to Secure Systems“ (SPP 2253) is scheduled to last for a period of six years. The call for projects for the first three-year funding period was advertised a few days ago, and the first projects are set to start at the beginning of 2020.

For more information go to the Nano Security: From Nano-Electronics to Secure Systems webpage on the University of Stuttgart website.