Hexbyte Glen Cove Dynamics of contact electrification thumbnail

Hexbyte Glen Cove Dynamics of contact electrification

Hexbyte Glen Cove

Scheme of the experimental setup. An electric equivalent circuit is displayed in the upper right corner. The charge is “split” between the capacity with the top and the bottom plate. Credit: Science Advances, doi: 10.1126/sciadv.abg7595

A new report on Science Advances developed by Mirco Kaponig and colleagues in physics and nanointegration in Germany, detailed the very basic concept of contact electrification between two metals. In a new experimental method, the researchers followed the charge of a small sphere bouncing on a grounded planar electrode on a timescale down to 1 microsecond. The team noted how the sphere discharged in the moment of contact lasting for 6 to 8 microseconds. At the moment of disruption of the electrical contact, the sphere regained charge far beyond expectations relative to the contact potential difference. The excess charge arose with increasing contact area.

Contact electrification

Contact electrification is a ubiquitous phenomenon that occurs when two surfaces touch. The process is an elementary method of triboelectricity that can be observed directly in daily life. The phenomenon is responsible for lightening in thunderstorms, sandstorms or volcanic plumes. The process can be of major concern when handling potentially explosive liquids or dusts. As a result, researchers have established empirical safety regulations to avoid hazards caused by electric discharges through triboelectric charging. Although the phenomenon was described for more than 2000 years, the underlying mechanisms are still debated. Scientists typically consider three kinds of charge transfer including the transfer of electrons, ions or material with partial charge. In metal-metal contacts, electrons can be transferred between two surfaces to establish contact potential. The amount of transferred charge also depended on the mutual capacity when the electric contact is disrupted, and the observed charge transfer strongly supported the concept of electron transfer for metal-metal contacts. The situation is less obvious for metal-insulator or insulator-insulator contacts. Kaponig et al. therefore presented a new experimental technique to analyze charge transfer during contact electrification, with unprecedented resolution.

Measurement of the charge on the lower plate of the capacitor and derived quantities. (A) The signal measured at the lower plate overlaid to a simulation according to Eqs. 1 and 3. It shows a perfect agreement, except at the very beginning and the top of the first parabola because of the field distortion in the vicinity of the entrance hole, which is not included in the numerical description. On the given scale, the signal noise is barely visible. The histogram in the upper right corner displays the charge on the sphere between the contacts. (B) The vertical position of the sphere bouncing on the plate derived from the contact times. (C) The potential calculated according to Eq. 4. in the study reveals that the sphere may reach a voltage of up to 10 V. Credit: Science Advances, doi: 10.1126/sciadv.abg7595

The experiments

The work revealed how the electric potential of a metallic particle bouncing from a metallic surface evolved with time. Based on the outcomes, Kaponig et al. noted how the charge increased with impact velocity in metal-metal contacts; a feature commonly observed with metal-insulator and insulator-insulator contacts but hither to unobserved for metal-metal contacts. During the experiments, this led to unexpectedly high electric potentials for purely metallic contacts. Since the electric contact was only established for a few microseconds during mechanical contact, the process did not retain the parameters of the charge before contact. The potential of the sphere was therefore only reduced to the contact potential of a few tenths of a volt. When the electric contact detached from the surface, however, the charge on the sphere established a potential of up to 3 V for less than 1 microsecond.

Charge transfer

Details of the first and second contact from about 100 μs before and 100 μs after the contact. (A) The measured and simulated charge as well as the derived potential for the first contact. The deviation marked by * is due to the “mechanical response” of the plate after the impact of the sphere. The horizontal line corresponds to the initial charge of the sphere or the zero point of the potential. The dashed vertical lines indicate the time interval of the mechanical contact. The plateau of the signal corresponds to the electrical contact. The insets sketch the charge distribution on the sphere and the plates. The relative size of the sphere is strongly exaggerated. The deformation is schematic; in reality, both the sphere and the surface are deformed. (B) The corresponding height of the sphere. The motion before and after the contact is almost linear on the short time scale. (C) The calculated capacity before and after the contact by the green line. During the contact, a tentative value proportional to the contact area is sketched by the dashed red line. The arrow points to the value of the capacity at the very moment when the electric contact is broken. It is assumed that the capacity is enhanced relative to the ideal geometry because of the deformation of the contact area by creating relatively large adjacent surfaces. (D) The measured and calculated charge as well as the derived potential for the second contact. Credit: Science Advances, doi: 10.1126/sciadv.abg7595

Scientists had previously studied the charge transfer of particles bouncing on an inclined surface based on contact-free electrostatic detection. Kaponig et al. therefore developed an experimental scheme to measure the charge before and after surface contact to follow the dynamics in real-time. In the setup, they obtained a resolution better than 1 microsecond in time for about 6000 electrons. They studied the motion and contact electrification by dropping gold spheres that are 1 mm in diameter through a small orifice into a parallel plate capacitor. The spheres bounced on a virtually grounded lower plate, allowing the scientists to measure the induced and transferred charges. The team performed the experiments in vacuum. The signal detected at the lower plate of the setup had two contributions including the charge on the sphere and the charge transferred to the sphere. The team noted the display signal of a gold sphere bouncing more than 15 times on the lower plate of the capacitor made of copper, the trajectory of the sphere consisted of segments of free fall, starting and completing via contact with the plate.

When Kaponig et al. closely inspected the signal, they identified the moments of contact by abrupt changes of the measured charge. They noted how the time spent between two contacts determined the segment of the trajectory. The team next applied a voltage at the ramp to guide the sphere to the entrance of the capacitor, where the sphere was positively charged before it entered the capacitor and became negatively charged during the first contact. The observed magnitude of the charge was unexpectedly high. The researchers then repeated the experiment with different initial charges, where the sphere became negatively charged at the first and following contact. Another key to understand contact electrification included the potential of the sphere. Based on the high magnitude of the charge on the sphere, the team noted a potential of several volts unexpectedly high for a purely metallic system. The electric contact was only established as a mechanical contact for a few microseconds. The potential of the sphere was therefore reduced to the contact potential of a few tenths of a volt. As the distance between the sphere and plate grew, the potential further increased.


The team described the observations using a metal-contact model in which the raised for the first-contact, followed by an enormous capacity formed at the interface due to the minimal distance between the charges. This capacity charged to the contact potential in the order of picocoulombs. Upon contact break, the two adjacent surfaces of the plate and sphere fit almost snugly to form a large area at close separation and a larger capacity, where the size of the area depended on the velocity of the sphere. In this way, Mirco Kaponig and colleagues showed how a metallic sphere bouncing from a metal plate achieved a potential of up to 10 V, due to a deformation of the contact area. This led to an increased capacity between the and the plate upon electric contact disruption. The results are important for contact electrification and triboelectricity for enhanced charge transfer.

More information:
Kaponig M. et al. Dynamics of contact electrification, Science Advances, DOI: 10.1126/sciadv.abg7595

Baytekin H. T. et al. The mosaic of surface charge in contact electrification, Science, 10.1126/science.1201512

Gimzewski J. K. et al. Transition from the tunneling regime to point contact studied using scanning tunneling microscopy, Physical Review B, doi.org/10.1103/PhysRevB.36.1284

© 2021 Science X Network

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Hexbyte Glen Cove Mixing solutions in the world's smallest test tubes thumbnail

Hexbyte Glen Cove Mixing solutions in the world’s smallest test tubes

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Credit: University of Manchester

Researchers based at the University of Manchester have demonstrated a new method for imaging live chemical reactions with atomic resolution using nanoscale test tubes created using two-dimensional (2D) materials.

The ability to observe solution-based with sub-nanometre resolution in real time has been highly sought after since the invention of the electron microscope 90 years ago.

Imaging the dynamics of a reaction can provide mechanistic insights and signpost strategies for tailoring the properties the resulting materials. A transmission electron microscope (TEM) is one of a few instruments capable of resolving individual atoms, though conventionally it requires completely dry samples imaged in a vacuum environment, precluding any wet chemical synthesis.

Based on previous work developing graphene liquid cells that allow TEM imaging of liquid-phase nanostructures, a team of researchers based at The University of Manchester’s National Graphene Institute, collaborating with researchers at the Leibniz University Hannover, have shown that two solutions can be mixed inside the microscope and imaged in real time.

The new research, published today in Advanced Materials details a new imaging platform that has been used to investigate the growth of calcium carbonate. This material is key to many natural and synthetic chemical processes. For example, calcium carbonate is the principal component in the shells of many marine organisms and its formation process is affected by increasing ocean acidification. Calcium carbonate precipitation is also essential for understanding concrete degradation and the material is a ubiquitous additive for many products from paper, plastics, rubbers, paints, and inks to pharmaceutics, cosmetics, construction materials, and animal foods. Nonetheless, despite this widespread use, the crystallization mechanism for calcium carbonate is widely debated.

In this work the authors provide the key new experimental evidence to support a theoretically predicted complex crystallization pathway. The team, led by Professor Sarah Haigh and Dr. Roman Gorbachev, designed a stack of different two-dimensional materials that contained nanoscale liquid solution compartments formed in microwells etched in hexagonal boron nitride spacer. These microwells were separated by an atomically thin membrane and sealed with graphene which acted as a ‘window’ to allow imaging with the electron beam.

The two pockets of solution were then mixed in the microscope by focussing the electron beam to locally fracture the separation membrane. This caused the two pre-loaded chemical reagents to mix in situ and the crystallization process could be monitored from start to finish.

Lead author Dr. Daniel Kelly explained: “One of the key features of our mixing cell design was the use of the electron beam to both image and puncture the cells. Unlike previous attempts, this made it possible for us to image the reaction from the first moment the solutions came into contact.”

The reaction timeline was captured using videos and advanced image processing technique to measure the evolution of the calcium carbonate species. The unique combination of high spatial resolution and control over the mixing time, as well as in situ elemental analysis, allowed the team to observe the transformation of liquid nanodroplets into amorphous precursors, and finally to crystalline particles. The results show the first visual confirmation of liquid-liquid phase separation, a theory that has been hotly debated amongst inorganic chemists over the past decade.

On the future direction for this new imaging platform, author Dr. Nick Clark said: “So far we have focused primarily on characterizing the formation of , however we are optimistic that this type of experiment could be extended to study many other complex mixing reactions.”

More information:
In Situ TEM Imaging of Solution-Phase Chemical Reactions Using 2D-Heterostructure Mixing Cells. Advanced Materials, doi.org/10.1002/adma.202100668

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Hexbyte Glen Cove Discovery of the oldest plant fossils on the African continent thumbnail

Hexbyte Glen Cove Discovery of the oldest plant fossils on the African continent

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A small plant whose axes divide several times before bearing oval sporangia. Credit: Univeristé de Liège

The analysis of very old plant fossils discovered in South Africa and dating from the Lower Devonian period documents the transition from barren continents to the green planet we know today. Cyrille Prestianni, a palaeobotanist at the EDDy Lab at the University of Liège (Belgium), participated in this study, the results of which have just been published in the journal Scientific Reports.

The greening of continents—or terrestrialisation—is undoubtedly one of the most important processes that our planet has undergone. For most of the Earth’s history, the continents were devoid of macroscopic life, but from the Ordovician period (480 million years ago) green algae gradually adapted to life outside the aquatic environment. The conquest of land by plants was a very long process during which plants gradually acquired the ability to stand upright, breathe in the air or disperse their spores. Plant fossils that document these key transitions are very rare. In 2015, during the expansion of the Mpofu Dam (South Africa), researchers discovered numerous in geological strata dated to the Lower Devonian (420—410 million years ago), making this a truly exceptional discovery.

Cyrille Prestianni, a palaeobotanist at the EDDy Lab (Evolution and Diversity Dynamics Lab) at the University of Liège, explains: “The discovery quickly proved to be extraordinary, since we are in the presence of the oldest fossil flora in Africa and it is very diversified and of exceptional quality. It is thanks to a collaboration between the University of Liège, the IRSNB (Royal Belgian Institute of Natural Sciences) and the New Albany Museum (South Africa) that this incredible discovery could be studied. The study, which has just been published in the journal Scientific Reports, describes this particularly diverse fossil flora with no less than 15 species analysed, three of which are new to science. This flora is also particularly interesting because of the quantity of complete specimens that have been discovered. These plants are small, with the largest specimens not exceeding 10 cm in height. They are simple plants, consisting of axes that divide two or three times and end in reproductive structures called sporangia.”

Mtshaelo kougaensis is a plant that bears complicated sporangia gathered at the end of the axes. Credit: University of Liège

The fossil flora of Mpofu suggests what the world might have been like when the largest plants were no taller than a few centimeters and almost no animals had yet been able to free themselves from the aquatic environment. It provides a better understanding of how the Earth went from a red rock devoid of life to the green planet we know today. These , simple as they are, are a crucial step in the construction of the environments that hosted the first land animals, arthropods. They form the basis of the long history of life on Earth, which continues today from dense tropical forests to the arid tundra of the north.

More information:
Robert W. Gess et al, An early Devonian flora from the Baviaanskloof Formation (Table Mountain Group) of South Africa, Scientific Reports (2021). DOI: 10.1038/s41598-021-90180-z

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Hexbyte Glen Cove Heat stress in U.S. may double by century's end thumbnail

Hexbyte Glen Cove Heat stress in U.S. may double by century’s end

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Potential heat stress risk due to combined climate and population projections. Credit: Mukherjee et al. (2021) Earth’s Future

Periods of extremely high heat are projected to double across the lower 48 states by 2100 if the world continues to emit high levels of greenhouse gases, according to a new study in Earth’s Future, an American Geophysical Union journal.

The will be felt most strongly in areas with growing populations. The Pacific Northwest, central California and the Great Lakes region could experience as much as a threefold increase compared to the past 40 years. Heat stress occurs when both the temperature and relative humidity get high enough that the can’t rid itself of the excess heat, leading to strokes, heat cramps and other health problems.

“Without doing any mitigation strategies, the impact of heat stress is likely to increase,” said Ashok Mishra, a at Clemson University and an author of the U.S. National Science Foundation-funded study.

Human-driven climate change is leading to an average increase in temperatures across the world. However, people don’t necessarily notice a slow, even warming as much as an extreme event.

Mishra and co-authors wanted to see how heat stress would increase at the same time as a general increase in temperature and . They assumed that while humans may experience higher temperatures on average in many areas, people will acclimatize to the new normal, but extremely index peaks, above even the yearly median values, will continue to have negative impacts on human health.

While previous research has usually examined how extreme heat events may increase in severity, frequency and duration, most studies have looked at one of these in isolation. Mishra and his colleagues calculated how all these might increase together in the future under a high emissions scenario.

Bruce Hamilton, a program director in NSF’s Directorate for Engineering, added that “the research underscores how vitally important it is to implement effective mitigation measures.”

More information:
Sourav Mukherjee et al, Anthropogenic Warming and Population Growth May Double US Heat Stress by the Late 21st Century, Earth’s Future (2021). DOI: 10.1029/2020EF001886

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Hexbyte Glen Cove Second cichlid fish species native to Mexico invading waterways in Louisiana thumbnail

Hexbyte Glen Cove Second cichlid fish species native to Mexico invading waterways in Louisiana

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Herichthys cyanoguttatus Rio Grande Cichlid. Credit: http://www.fishesoftexas.org/taxa/herichthys-cyanoguttatus

A Case Western Reserve University scientist has played the lead role in identifying an invasive species related to one already threatening other fish in the waters of the southern United States.

That discovery tells natural-resource managers and conservationists they may have a bigger problem on their hands than they thought.

“The introduction of non-native aquatic is one of the to around the world,” said Case Western Reserve biologist Ronald Oldfield, who led a team of researchers that identified a second invasive fish species living in the New Orleans area. “Humans are permanently harming natural environments around the world through the introduction of non-native species.”

An invasive relative

The newly identified species is related to the Rio Grande Cichlid, sometimes called the Texas Cichlid, a fish native to the river it’s named after that forms the southern border of Texas. About the size of a human hand, its scales show off bright bluish-green spots over a gray-green background.

But that attractive coloring also makes the Rio Grande Cichlid (Herichthys cyanoguttatus) a popular pet. So the fish most likely escaped or was dumped into the water by their owners. It’s now found throughout Texas, Louisiana and Florida.

Scientists have documented that the Rio Grande Cichlid can dominate the waters by being aggressively territorial with other fish, especially bluegill.

They’re taking the threat seriously in Louisiana, in particular. The state has made it illegal to own the fish and requires anyone who catches one to kill it immediately. And private groups have set up fishing contests to encourage removing them from the water.

But scientists and natural-resource managers thought there was only one cichlid to worry about—until Oldfield, a senior instructor in Case Western Reserve’s Department of Biology, and his collaborators did some sleuthing.

“I believed there were two distinct fish species the moment I saw the Louisiana specimens,” Oldfield said. “It just took many years of gathering data to convince everyone else.”

The discovery

Over the course of three years, Oldfield raised offspring of fish caught in the wild in Louisiana and began marking differences between those and the Rio Grande Cichlid.

Oldfield and his collaborating researchers were aided by hundreds of fish images fishing enthusiasts and naturalists posted on iNaturalist and the Cichlid Room Companion, websites that allow the public to upload photographs of animals observed in the wild. The researchers were able to confirm two distinct species—mainly by color differences.

Oldfield and his collaborators published their discovery of the lowland cichlid (Herichthys carpintis) in the journal Miscellaneous Publications of the Museum of Zoology, University of Michigan.

Oldfield worked with Tom Lorenz, an associate professor at Georgia Southwestern State University, William I. Lutterschmidt of Sam Houston State, and Dean Hendrickson and Adam Cohen at the University of Texas at Austin.

Environmental implications

This newly discovered cichlid joins an increasing list of threatening natural populations of plants or animals.

It’s a list that also adds up financially: Containing the spread of invasive plants and animals nationally—from the Asian Carp threatening the Great Lakes to the giant rodent, nutria—costs an estimated hundreds of millions of dollars, according to various government agencies.

Invasive are especially troublesome. Agencies from the U.S. Fish & Wildlife service to the National Oceanic and Atmospheric Administration’s Fisheries Division consider aquatic invasive species to be a threat to biodiversity worldwide, second only to habitat loss.

“It is important to understand the identity of introduced species, and understanding the biology of not one, but two, species of Herichthys will be necessary to mitigate their spread,” Oldfield said. “They may very well differ in the way they affect native species. So far, there has been little research done on the effects that they might have, and that’s what’s extra scary.”

More information:
Live Color Patterns Diagnose Species: A Tale of Two Herichthys dx.doi.org/10.7302/916

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Hexbyte Glen Cove Scientists co-author new COP26 report on ocean and climate negotiations thumbnail

Hexbyte Glen Cove Scientists co-author new COP26 report on ocean and climate negotiations

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Credit: CC0 Public Domain

A new report co-authored by University of Liverpool ocean scientists highlights why the ocean matters in climate negotiations and suggests positive actions nations can take as the countdown to COP26 is underway

On World Oceans Day, and ahead of the G7 later this week, a group of leading UK experts -including Professor Jonathan Sharples and Professor Ric Williams from the University’s School of Environmental Sciences—shine a spotlight on the critical role the plays in greatly slowing the rate of change but also the subsequent impacts of this and why support from nations for better inclusion of the ocean at the United Nations climate negotiations, such as COP26 in Glasgow this November, is so important.

Titled `Why the ocean matters in climate negotiations,” the briefing summarizes the latest research and knowledge on the importance of the ocean, as well as offering a range of opportunities to nations in order to ensure that the ocean can be developed sustainably for the benefits it provides to people around the world.

The key messages are:

  • The ocean has greatly slowed the rate of climate change. But at a cost: the ocean has also warmed, acidified and lost oxygen, whilst circulation patterns are changing, and sea levels are rising. The continuation of these changes not only threatens , but also the future ability of the ocean to indirectly support all life on Earth.
  • A healthy and biodiverse ocean provides food, wellbeing, cultural heritage, and support for the sustainable livelihoods of billions of people—as well as mitigation and adaptation options for climate change.
  • Rapid reduction in greenhouse gas emissions to meet the Paris Agreement will decrease impacts on the ocean and benefit its ecosystems and all of society.
  • As part of the “climate system” the ocean needs to be better integrated in UNFCCC mitigation, adaptation and financial processes, including Nationally Determined Contributions, National Adaptation Plans and the Global Stocktake.
  • Improved ocean governance and management is needed to scale up marine protection and sustainable management of both the high seas and coastal waters.
  • Sustained, global ocean observations and projections of ocean physics, chemistry and biology are essential to inform better short and long-term policy-making for the benefit of people, nature and the economy.
  • Innovative ocean finance is required to achieve a sustainable ocean economy and protect the ocean’s natural capital.

Led by Plymouth Marine Laboratory, the breifing has been developed by a team of experts from leading UK marine and universities and centres and published in association with the COP26 Universities Network, and it also makes suggestions on how the ocean can be better incorporated in the United Nations Framework Convention on Climate Change (UNFCCC) process.

The experts also emphasise the ecological, social and economic importance of coastal seas and the open ocean. Coastal seas are often busy places and face a diverse range of pressures so, therefore, require careful and sensitive management to not only ensure protection but also help these areas meet their potential for both climate change mitigation and adaptation.

Further afield but no less important, the open ocean holds about 90% of the extra heat stored on the planet from global warming and the biological activity that occurs in the upper layers accounts for about half of the primary production on Earth. Traditional sectoral and regional approaches to the High Seas needs to be replaced by an effective all-ocean system management, including an integrated observational and data infrastructure and increased financial investment.

Liverpool’s Professor Jonathan Sharples, one of the report’s authors, said: “Our coastal seas are under particular threat from climate warming and over-exploitation. But at the same time with proper management, they have great capacity to help us achieve net zero carbon emissions and prevent further drift of Earth’s climate into a dangerous future.”

Professor Ric Williams, Chair in Ocean Sciences at the University also co-authored the report. He said: “The ocean acts to mitigate some of the adverse effects of climate change and thankfully reduces surface warming by taking up and storing excess heat and carbon. However, that mitigation comes at a price, the ocean itself is getting warmer, sea level is rising and the ocean is acidifying. This report is to highlight the importance of the ocean in the coming climate COP26 talks in Glasgow.”

Peter Thomson, UN Secretary-General’s Special Envoy for the Ocean, commented: “It is heartening to see this timely ocean briefing by leading UK academics on why the ocean matters in climate negotiations. The briefing hits the nail on the head when it highlights that while a healthy and biodiverse ocean is central to all life on Earth, it is too often neglected in high-level climate negotiations. The Climate-Ocean nexus is inseparable. This is a fundamental message as we prepare for the all-important UNFCCC COP26 in Glasgow this November.”

Professor Hans-Otto Pörtner, marine biologist at the Alfred Wegener Institute and the co-chair of the Intergovernmental Panel on Climate Change (IPCC) Working Group II, commented: “This is an impressive account on the ocean under climate change in a nutshell. It touches on what the ocean does for humankind and the living planet, how it is suffering from being overburdened by human waste and human-made climate change. At the same time, with , the ocean offers opportunities that can help strengthening its resilience, its biosphere and other services to people and their well-being.”

Lead author, Dr. Carol Turley OBE of Plymouth Marine Laboratory, said: “The ocean is at the front line of climate change experiencing massive changes because it is receiving much of the excess heat, CO2 and water caused by our changing climate so ambitious mitigation is essential for the ocean. Yet it also offers a wealth of adaptation options such as creation of offshore wind, protection of marine carbon stores, sustainable fisheries and creation of marine protected areas—so the ocean is going to be a busy place requiring improved ocean governance and management and the finance and observational capacity to support and monitor how it is faring if it is going to be managed sustainably for the benefit of its biodiversity and society. It seems amazing to me that the largest ecosystem on Earth, the ocean, has received such little attention during previous —this briefing aims to help rectify that by explaining why the ocean is important to life on Earth and by giving recommendations for actions that nations can take.”

The University of Liverpool’s Climate Futures research challenge brings together experts in a wide range of disciplines to explore impacts of climate change, develop solutions to environmental challenges and address knowledge gaps.

Find out more about the University’s  work on climate science by visiting OceanClimateAtUoL

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Hexbyte Glen Cove A new material made from carbon nanotubes can generate electricity by scavenging energy from its environment thumbnail

Hexbyte Glen Cove A new material made from carbon nanotubes can generate electricity by scavenging energy from its environment

Hexbyte Glen Cove

Credit: Pixabay/CC0 Public Domain

MIT engineers have discovered a new way of generating electricity using tiny carbon particles that can create a current simply by interacting with liquid surrounding them.

The liquid, an , draws electrons out of the particles, generating a current that could be used to drive or to power micro- or nanoscale robots, the researchers say.

“This mechanism is new, and this way of generating is completely new,” says Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT. “This technology is intriguing because all you have to do is flow a solvent through a bed of these particles. This allows you to do electrochemistry, but with no wires.”

In a new study describing this phenomenon, the researchers showed that they could use this to drive a reaction known as alcohol oxidation—an organic chemical reaction that is important in the chemical industry.

Strano is the senior author of the paper, which appears today in Nature Communications. The lead authors of the study are MIT graduate student Albert Tianxiang Liu and former MIT researcher Yuichiro Kunai. Other authors include former graduate student Anton Cottrill, postdocs Amir Kaplan and Hyunah Kim, graduate student Ge Zhang, and recent MIT graduates Rafid Mollah and Yannick Eatmon.

Unique properties

The new discovery grew out of Strano’s research on nanotubes—hollow tubes made of a lattice of carbon atoms, which have unique electrical properties. In 2010, Strano demonstrated, for the first time, that carbon nanotubes can generate “thermopower waves.” When a is coated with layer of fuel, moving pulses of heat, or thermopower waves, travel along the tube, creating an electrical current.

That work led Strano and his students to uncover a related feature of carbon nanotubes. They found that when part of a nanotube is coated with a Teflon-like polymer, it creates an asymmetry that makes it possible for electrons to flow from the coated to the uncoated part of the tube, generating an . Those electrons can be drawn out by submerging the particles in a solvent that is hungry for electrons.

To harness this special capability, the researchers created electricity-generating particles by grinding up carbon nanotubes and forming them into a sheet of paper-like material. One side of each sheet was coated with a Teflon-like polymer, and the researchers then cut out , which can be any shape or size. For this study, they made particles that were 250 microns by 250 microns.

When these particles are submerged in an organic solvent such as acetonitrile, the solvent adheres to the uncoated surface of the particles and begins pulling electrons out of them.

“The solvent takes electrons away, and the system tries to equilibrate by moving electrons,” Strano says. “There’s no sophisticated battery chemistry inside. It’s just a particle and you put it into solvent and it starts generating an electric field.”

Particle power

The current version of the particles can generate about 0.7 volts of electricity per particle. In this study, the researchers also showed that they can form arrays of hundreds of particles in a small test tube. This “packed bed” reactor generates enough energy to power a chemical reaction called an alcohol oxidation, in which an alcohol is converted to an aldehyde or a ketone. Usually, this reaction is not performed using electrochemistry because it would require too much external current.

“Because the packed bed reactor is compact, it has more flexibility in terms of applications than a large electrochemical reactor,” Zhang says. “The particles can be made very small, and they don’t require any external wires in order to drive the electrochemical reaction.”

In future work, Strano hopes to use this kind of energy generation to build polymers using only carbon dioxide as a starting material. In a related project, he has already created polymers that can regenerate themselves using carbon dioxide as a building material, in a process powered by solar energy. This work is inspired by carbon fixation, the set of chemical reactions that plants use to build sugars from carbon dioxide, using energy from the sun.

In the longer term, this approach could also be used to power micro- or nanoscale robots. Strano’s lab has already begun building robots at that scale, which could one day be used as diagnostic or environmental sensors. The idea of being able to scavenge energy from the environment to power these kinds of robots is appealing, he says.

“It means you don’t have to put the energy storage on board,” he says. “What we like about this mechanism is that you can take the energy, at least in part, from the environment.”

More information:
Albert Tianxiang Liu et al, Solvent-induced electrochemistry at an electrically asymmetric carbon Janus particle, Nature Communications (2021). DOI: 10.1038/s41467-021-23038-7

A new material made from carbon nanotubes can generate electricity by

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Hexbyte Glen Cove Experiment evaluates the effect of human decisions on climate reconstructions

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Credit: Unsplash/CC0 Public Domain

The first double-blind experiment analyzing the role of human decision-making in climate reconstructions has found that it can lead to substantially different results.

The experiment, designed and run by researchers from the University of Cambridge, had multiple research groups from around the world use the same raw tree-ring data to reconstruct temperature changes over the past 2,000 years.

While each of the reconstructions clearly showed that recent warming due to is unprecedented in the past two thousand years, there were notable differences in variance, amplitude and sensitivity, which can be attributed to decisions made by the researchers who built the individual reconstructions.

Professor Ulf Büntgen from the University of Cambridge, who led the research, said that the results are “important for transparency and truth—we believe in our data, and we’re being open about the decisions that any has to make when building a reconstruction or model.”

To improve the reliability of reconstructions, the researchers suggest that teams make multiple reconstructions at once so that they can be seen as an ensemble. The results are reported in the journal Nature Communications.

Information from tree rings is the main way that researchers reconstruct past climate conditions at annual resolutions: as distinctive as a fingerprint, the rings formed in trees outside the tropics are annually precise growth layers. Each ring can tell us something about what conditions were like in a particular growing season, and by combining data from many trees of different ages, scientists are able to reconstruct past climate conditions going back hundreds and even thousands of years.

Reconstructions of past climate conditions are useful as they can place current climate conditions or future projections in the context of past natural variability. The challenge with a climate reconstruction is that—absent a —there is no way to confirm it is correct.

“While the information contained in remains constant, humans are the variables: they may use different techniques or choose a different subset of data to build their reconstruction,” said Büntgen, who is based at Cambridge’s Department of Geography, and is also affiliated with the CzechGlobe Centre in Brno, Czech Republic. “With any reconstruction, there’s a question of uncertainty ranges: how certain you are about a certain result. A lot of work has gone into trying to quantify uncertainties in a statistical way, but what hasn’t been studied is the role of decision-making.

“It’s not the case that there is one single truth—every decision we make is subjective to a greater or lesser extent. Scientists aren’t robots, and we don’t want them to be, but it’s important to learn where the decisions are made and how they affect the outcome.”

Büntgen and his colleagues devised an experiment to test how decision-making affects climate reconstructions. They sent raw tree ring data to 15 research groups around the world and asked them to use it to develop the best possible large-scale climate reconstruction for in the Northern hemisphere over past 2000 years.

“Everything else was up to them—it may sound trivial, but this sort of experiment had never been done before,” said Büntgen.

Each of the groups came up with a different reconstruction, based on the decisions they made along the way: the data they chose or the techniques they used. For example, one group may have used instrumental target data from June, July and August, while another may have only used the mean of July and August only.

The main differences in the reconstructions were those of amplitude in the data: exactly how warm was the Medieval warming period, or how much cooler a particular summer was after a large volcanic eruption.

Büntgen stresses that each of the reconstructions showed the same overall trends: there were periods of warming in the 3rd century, as well as between the 10th and 12th century; they all showed abrupt summer cooling following clusters of large volcanic eruptions in the 6th, 15th and 19th century; and they all showed that the recent warming since the 20th and 21st century is unprecedented in the past 2000 years.

“You think if you have the start with the same data, you will end up with the same result, but climate reconstruction doesn’t work like that,” said Büntgen. “All the reconstructions point in the same direction, and none of the results oppose one another, but there are differences, which must be attributed to decision-making.”

So, how will we know whether to trust a particular climate in future? In a time where experts are routinely challenged, or dismissed entirely, how can we be sure of what is true? One answer may be to note each point where a decision is made, consider the various options, and produce multiple reconstructions. This would of course mean more work for climate scientists, but it could be a valuable check to acknowledge how decisions affect outcomes.

Another way to make climate reconstructions more robust is for groups to collaborate and view all their reconstructions together, as an ensemble. “In almost any , you can point to a single study or result that tells you what to hear,” he said. “But when you look at the body of scientific evidence, with all its nuances and uncertainties, you get a clearer overall picture.”

More information:
The influence of decision-making in tree ring-based climate reconstructions, Nature Communications (2021). DOI: 10.1038/s41467-021-23627-6

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Hexbyte Glen Cove A few common bacteria account for majority of carbon use in soil thumbnail

Hexbyte Glen Cove A few common bacteria account for majority of carbon use in soil

Hexbyte Glen Cove

Bacterial “miners” shown in relief working to process soil nutrients, some more efficiently than others. Bradyrhizobium, one of the three top nutrient processors identified in the study, is shown here consolidating its control of carbon from a glucose addition, processing the nutrients with industrial efficiency (in the form of a bucket wheel excavator). Credit: Victor O. Leshyk, Center for Ecosystem Science and Society, Northern Arizona University

Just a few bacterial taxa found in ecosystems across the planet are responsible for more than half of carbon cycling in soils. These new findings, made by researchers at Northern Arizona University and published in Nature Communications this week, suggest that despite the diversity of microbial taxa found in wild soils gathered from four different ecosystems, only three to six groups of bacteria common among these ecosystems were responsible for most of the carbon use that occurred.

Soil contains twice as much as all vegetation on earth, and so predicting how carbon is stored in soil and released as CO2 is a critical calculation in understanding future climate dynamics. The research team, which included scientists from Pacific Northwest National Laboratory, Lawrence Livermore National Laboratory, University of Massachusetts-Amherst, and West Virginia University, is asking how such key bacterial processes should be accounted for in earth system and .

“We found that carbon cycling is really controlled by a few groups of common bacteria,” said Bram Stone, a postdoctoral researcher at the Center for Ecosystem Science and Society at Northern Arizona University who led the study. “The sequencing era has delivered incredible insight into how diverse the microbial world is,” said Stone, who is now at Pacific Northwest National Laboratory. “But our data suggest that when it comes to important functions like soil respiration, there might be a lot of redundancy built into the soil community. It’s a few common, abundant actors who are making the most difference.”

Those bacteria—Bradyrhizobium, the Acidobacteria RB41, and Streptomyces—were better than their rarer counterparts at using both existing soil carbon and nutrients added to the soil. When carbon and nitrogen were added, these already dominant lineages of bacteria consolidated their control of nutrients, gobbling up more and growing faster relative to other taxa present. Though the researchers identified thousands of unique organisms, and hundreds of distinct genera, or collections of species (for example, the genus Canis includes wolves, coyotes, and dogs), only six were needed to account for more than 50 percent of carbon use, and only three were responsible for more than half the carbon use in the nutrient-boosted soil.

Credit: CC0 Public Domain

Using water labeled with special isotopes of oxygen, Stone and his team sequenced DNA found in soil samples, following the oxygen isotopes to see which taxa incorporated it into their DNA, a signal that indicates growth. This technique, called quantitative stable isotope probing (qSIP), allows scientists to track which bacteria are growing in wild soil at the level of individual taxa. Then the team accounted for the abundance of each taxon and modeled how efficiently bacteria consume soil carbon. The model that included taxonomic specificity, genome size, and growth predicted the measured CO2 release much more accurately than models that looked only at how abundant each bacterial group was. It also showed that just a few taxa produced most of the CO2 that the researchers observed.

“Better understanding how individual organisms contribute to carbon cycling has important implications for managing soil fertility and reducing uncertainty in climate change projections,” said Kirsten Hofmockel, Microbiome Science Team Lead at Pacific Northwest National Laboratory and a co-author of the study. “This research teases apart taxonomic and functional diversity of soil microorganisms and asks us to consider biodiversity in a new way.”

“The microbial demographic data that this technique reveals lets us ask more nuanced questions,” said Stone. “Where we used to characterize a microbial community by its dominant function, the way a whole state is often reported to have voted ‘for’ or ‘against’ a ballot proposition, now, with qSIP, we can see who is driving that larger pattern—the ‘election results,’ if you will—at the level of individual microbial neighborhoods, city blocks.

“In this way, we can start to identify which organisms are performing important functions, like carbon sequestration, and study those more closely.”

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Hexbyte Glen Cove Biden administration will restore key environmental protections thumbnail

Hexbyte Glen Cove Biden administration will restore key environmental protections

Hexbyte Glen Cove

The Endangered Species Act is credited with saving iconic species like the bald eagle.

The administration of President Joe Biden on Friday announced it would restore protections under the Endangered Species Act, a law credited with saving iconic animals like the gray wolf and bald eagle, which were loosened by his predecessor Donald Trump.

Conservation groups welcomed the move but said they were concerned about how long the reversal might take.

“The US Fish and Wildlife Service (FWS) is committed to working with diverse federal, Tribal, state and industry partners to not only protect and recover America’s imperiled wildlife but to ensure cornerstone laws like the Endangered Species Act are helping us meet 21st century challenges,” said the agency’s Martha Williams.

The executive branch doesn’t have the power to change an act of Congress, but under Trump the protections for plants and wildlife were tweaked in key ways.

They included removing a rule that automatically conveys the same protections to threatened species and , and allowing information on economic impact to be gathered when making determinations on how wildlife is listed.

The FWS now proposes to undo those changes, saying it would formulate new rules in the coming months.

“We are grateful the Biden administration is moving to protect the most imperiled species by reversing the Trump-era rules, but time is of the essence,” environmental law non-profit group Earthjustice said in response.

“Each day that goes by is another day that puts our imperiled species and their habitats in danger.”

© 2021 AFP

Biden administration will restore key environmental protections (2021, June 5)
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