Hexbyte Glen Cove Magnetism meets topology on a superconductor's surface thumbnail

Hexbyte Glen Cove Magnetism meets topology on a superconductor’s surface

Hexbyte Glen Cove

An illustration depicting a topological surface state with an energy band gap (an energy range where electrons are forbidden) between the apices of the top and corresponding bottom cones (allowed energy bands, or the range of energies electrons are allowed to have). A topological surface state is a unique electronic state, only existing at the surface of a material, that reflects strong interactions between an electron’s spin (red arrow) and its orbital motion around an atom’s nucleus. When the electron spins align parallel to each another, as they do here, the material has a type of magnetism called ferromagnetism. Credit: Dan Nevola, Brookhaven National Laboratory

Electrons in a solid occupy distinct energy bands separated by gaps. Energy band gaps are an electronic “no man’s land,” an energy range where no electrons are allowed. Now, scientists studying a compound containing iron, tellurium, and selenium have found that an energy band gap opens at a point where two allowed energy bands intersect on the material’s surface. They observed this unexpected electronic behavior when they cooled the material and probed its electronic structure with laser light. Their findings, reported in the Proceedings of the National Academy of Sciences, could have implications for future quantum information science and electronics.

The particular compound belongs to the family of iron-based , which were initially discovered in 2008. These materials not only conduct electricity without resistance at relatively higher temperatures (but still very cold ones) than other classes of superconductors but also show magnetic properties.

“For a while, people thought that superconductivity and magnetism would work against each other,” said first author Nader Zaki, a scientific associate in the Electron Spectroscopy Group of the Condensed Matter Physics and Materials Science (CMPMS) Division at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory. “We have explored a material where both develop at the same time.”

Aside from superconductivity and magnetism, some iron-based superconductors have the right conditions to host “topological” surface states. The existence of these unique electronic states, localized at the surface (they do not exist in the bulk of the material), reflects between an electron’s spin and its orbital motion around the nucleus of an atom.

“When you have a superconductor with topological surface properties, you’re excited by the possibility of topological superconductivity,” said corresponding author Peter Johnson, leader of the Electron Spectroscopy Group. “Topological superconductivity is potentially capable of supporting Majorana fermions, which could serve as qubits, the information-storing building blocks of quantum computers.”

Quantum computers promise tremendous speedups for calculations that would take an impractical amount of time or be impossible on traditional computers. One of the challenges to realizing practical quantum computing is that qubits are highly sensitive to their environment. Small interactions cause them to lose their quantum state and thus stored information becomes lost. Theory predicts that Majorana fermions (sought-after quasiparticles) existing in superconducting are immune to environmental disturbances, making them an ideal platform for robust qubits.

Seeing the iron-based superconductors as a platform for a range of exotic and potentially important phenomena, Zaki, Johnson, and their colleagues set out to understand the roles of topology, superconductivity and magnetism.

CMPMS Division senior physicist Genda Gu first grew high-quality single crystals of the iron-based compound. Then, Zaki mapped the electronic band structure of the material via laser-based photoemission spectroscopy. When light from a laser is focused onto a small spot on the material, electrons from the surface are “kicked out” (i.e., photoemitted). The energy and momentum of these electrons can then be measured.

When they lowered the temperature, something surprising happened.

“The material went superconducting, as we expected, and we saw a superconducting gap associated with that,” said Zaki. “But what we didn’t expect was the topological surface state opening up a second gap at the Dirac point. You can picture the energy band structure of this surface state as an hourglass or two cones attached at their apex. Where these cones intersect is called the Dirac point.”

As Johnson and Zaki explained, when a gap opens up at the Dirac point, it’s evidence that has been broken. Time-reversal symmetry means that the laws of physics are the same whether you look at a system going forward or backward in time—akin to rewinding a video and seeing the same sequence of events playing in reverse. But under time reversal, electron spins change their direction and break this symmetry. Thus, one of the ways to break time-reversal symmetry is by developing magnetism—specifically, ferromagnetism, a type of magnetism where all electron spins align in a parallel fashion.

“The system is going into the superconducting state and seemingly magnetism is developing,” said Johnson. “We have to assume the magnetism is in the surface region because in this form it cannot coexist in the bulk. This discovery is exciting because the material has a lot of different physics in it: superconductivity, topology, and now magnetism. I like to say it’s one-stop shopping. Understanding how these phenomena arise in the material could provide a basis for many new and exciting technological directions.”

As previously noted, the material’s superconductivity and strong spin-orbit effects could be harnessed for quantum information technologies. Alternatively, the material’s magnetism and strong spin-orbit interactions could enable dissipationless (no energy loss) transport of electrical current in electronics. This capability could be leveraged to develop electronic devices that consume low amounts of power.

Coauthors Alexei Tsvelik, senior scientist and group leader of the CMPMS Division Condensed Matter Theory Group, and Congjun Wu, a professor of physics at the University of California, San Diego, provided theoretical insights on how time reversal symmetry is broken and magnetism originates in the surface region.

“This discovery not only reveals deep connections between topological superconducting states and spontaneous magnetization but also provides important insights into the nature of superconducting gap functions in iron-based superconductors—an outstanding problem in the investigation of strongly correlated unconventional superconductors,” said Wu.

In a separate study with other collaborators in the CMPMS Division, the experimental team is examining how different concentrations of the three elements in the sample contribute to the observed phenomena. Seemingly, tellurium is needed for the topological effects, too much iron kills superconductivity, and selenium enhances superconductivity.

In follow-on experiments, the team hopes to verify the time-reversal symmetry breaking with other methods and explore how substituting elements in the compound modifies its electronic behavior.

“As materials scientists, we like to alter the ingredients in the mixture to see what happens,” said Johnson. “The goal is to figure out how superconductivity, topology, and magnetism interact in these complex materials.”



More information:
Nader Zaki et al. Time-reversal symmetry breaking in the Fe-chalcogenide superconductors, Proceedings of the National Academy of Sciences (2021). DOI: 10.1073/pnas.2007241118

Citation:
Magnetism meets topology on a superconductor’s surface (2021, March 17)
retrieved 17 March 2021
from https://phys.org/news/2021-03-magnetism-topology-superconductor-surface.html

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Hexbyte Glen Cove Pioneering study gives new insight into formation of copper deposits thumbnail

Hexbyte Glen Cove Pioneering study gives new insight into formation of copper deposits

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Credit: Pixabay/CC0 Public Domain

A groundbreaking study has given new insights into how copper deposit-forming fluids are transported naturally from their source deep underground towards the Earth’s surface.

A team of geologists, led by Lawrence Carter from the University of Exeter’s Camborne School of Mines, has published a new theory for how porphyry deposits form.

Porphyry deposits provide around 75 percent of the world’s copper which is in increasing demand for , power infrastructure and green technologies such as wind turbines. They originally develop several kilometers below the Earth’s surface above large magma chambers. Not only are rare but most large near-surface examples have already been found. Any new model for how and where they form will be of great interest to mining companies.

In the new study, the researchers have shown that vast quantities of mineralising fluids could be extracted and transported from their source magmas and focussed into the ore-forming environment through “crystal mush dykes.”

Lawrence Carter, a final year Ph.D. student at Camborne School of Mines, based at the University of Exeter’s Penryn Campus said: “Our study addresses the missing link in models for the formation of porphyry-type copper deposits—how vast quantities of mineralising fluids are extracted and transported from their source magmas and focussed into the ore-forming environment.

“In doing so we provide the first field, petrographic and microscale evidence for transport through what we term ‘crystal mush dykes.” Their recognition is paramount to the development of more reliable porphyry exploration models and has significance for other ore-forming systems and volcanic processes.”

Collaborating with scientists from the British Geological Survey (BGS) and University of Surrey, this research involved field studies and micro-textural and geochemical analyzes of samples from the archetypal Yerington porphyry district in Nevada, where an exceptional ~8 km palaeo-vertical cross-section through a number of porphyry copper deposit systems is exposed.

The team were able to identify a wormy interconnected network of quartz within dykes found in rocks that were once beneath the copper deposits. This represents palaeo-porosity in a once permeable magmatic crystal mush of feldspar and quartz. The mush acted as conduits for vast quantities of porphyry-deposit-forming fluids from deep portions of underlying magmas.

It is believed that this breakthrough may provide insights for the discovery of new porphyry copper deposits, and the proposed mechanism key to the formation of other ore deposit types as well as degassing processes in volcanic systems.

The paper, titled “Crystal mush dykes as conduits for mineralising fluids in the Yerington porphyry copper district, Nevada,” was published in the leading journal Nature Communications Earth & Environment on March 17, 2021.



More information:
Lawrence C. Carter et al. Crystal mush dykes as conduits for mineralising fluids in the Yerington porphyry copper district, Nevada, Communications Earth & Environment (2021). DOI: 10.1038/s43247-021-00128-4

Citation:
Pioneering study gives new insight into formation of copper deposits (2021, March 17)
retrieved 17 March 2021
from https://phys.org/news/2021-03-insight-formation-copper-deposits.html

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Hexbyte Glen Cove Lethal pollution high in 2020 despite lockdowns: report thumbnail

Hexbyte Glen Cove Lethal pollution high in 2020 despite lockdowns: report

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Beijing was among the most polluted cities

Deadly small particle pollution in dozens of nations exceeded World Health Organization recommendations last year despite Covid lockdowns, according to a report released Tuesday.

The partial or complete shutdown of transport and industry for months at a time in 2020 reduced average levels of so-called PM2.5 pollution across the world, including in major cities, the IQAir quality report found.

Concentrations of the life-shortening particles—cast off by traffic pollution and burning fossil fuels—dropped 11 percent in Beijing, 13 percent in Chicago, 15 percent in New Delhi, 16 percent in London, and 16 percent in Seoul.

At least 60 percent of India’s cities were more breathable last year than in 2019, and all of them had cleaner air than in 2018.

“Many parts of the world experienced unprecedented—but short-lived—improvements in air quality in 2020,” said Lauri Myllyvirta, lead analyst at the Centre for Research on Energy and Clean Air (CREA) and co-author of the report.

“This meant tens of thousands of avoided deaths from air pollution.”

But only 24 of 106 countries monitored met WHO safety guidelines, said the report, based on the world’s largest database of ground-level air pollution measurements.

China and many South Asian nations experienced PM2.5 pollution several time greater than WHO recommended thresholds, and in some regions the concentration was six to eight times higher.

Twenty-two of the world’s more polluted cities are in India.

Bangladesh, Pakistan, India, Mongolia and Afghanistan topped the 2020 ranking, with average annual PM2.5 concentrations between 77 and 47 microgrammes per cubic metre (mcg/m3) of air.

Deep into the lungs

The UN says PM2.5 density should not top 25 mcg/m3 in any 24-hour period, or 10 mcg/m3 averaged across an entire year.

The most polluted capital cities in the world last year were New Delhi (84 mcg/m3) and Dhaka (77), with Jakarta, Kathmandu, Islamabad, Hanoi and Beijing all in the top 20.

Graphic ranking cities by pollution levels based on annual average PM2.5 concentration

About half of all European cities exceed WHO’s suggested limits.

Air pollution levels were made worse in 2020—tied for the hottest year on record—by climate change, the report noted.

Wildfires fuelled by scorching heatwaves led to extremely high pollution levels in California, South America and Australia.

Data from the first few months show PM2.5 pollution returning to pre-pandemic levels.

The European Space Agency (ESA) reported Monday that concentrations of another health-damaging air pollutant that dipped in 2020, nitrogen oxide (NO2), has also rebounded and, in some parts of the world, is on the rise.

After dropping, for example, about 40 percent last February in Chinese megacities Beijing and Chongqing, NO2 levels shot back up last month to 2019 in Beijing, and nearly double from 2019 levels in Chongqing.

“We expected air pollution to rebound as lockdowns are lifted across the globe,” Claus Zehner, ESA’s mission manager for the Copernicus Sentinel-5P Earth monitoring satellite, said in a statement.

“In the coming weeks and months, we expect increases of nitrogen dioxide concentrations also over Europe.”

Air pollution shortens lives worldwide by nearly three years on average, and causes more than eight million premature deaths annually, earlier studies have found.

The WHO calculates 4.2 million deaths from outdoor air pollution, but has underestimated the impact on cardiovascular disease, recent research has shown.

Average lifespan is cut 4.1 years in China, 3.9 years in India, and 3.8 years in Pakistan.

In Europe, life expectancy is shortened by eight months.

PM2.5 particles penetrate deep into the lungs and enter the bloodstream. In 2013, the WHO classified it as a cancer-causing agent.

Compared to other causes of premature death, air pollution worldwide kills 19 times more people each year than malaria, nine times more than HIV/AIDS, and three times more than alcohol.



© 2021 AFP

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Lethal pollution high in 2020 despite lockdowns (2021, March 16)
retrieved 16 March 2021
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Hexbyte Glen Cove Migration routes of one of Britain's largest ducks revealed for the first time thumbnail

Hexbyte Glen Cove Migration routes of one of Britain’s largest ducks revealed for the first time

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Credit: ©Philip Croft/BTO

New research, just published in the journal Ringing & Migration, has used state of the art tracking technology to investigate how one of Britain’s largest ducks, the Shelduck, interacts with offshore wind turbines during their migration across the North Sea.

Their findings reveal—for the first time—the length, speed and flight heights of this journey.

Offshore are a key part of many governments’ strategies to reduce carbon emissions and mitigate climate change impacts. However, it is important to understand how they might affect wildlife.

The risk of colliding with , is a particular concern to travelling across the sea, and there is also a potential increased energetic cost if wind farms act as a barrier that migrating must fly around.

The majority of British and Irish Shelduck undergo a ‘moult migration’ to the Wadden Sea, which runs along the coasts of the Netherlands, Germany and Denmark. They make this journey every year in late summer, after they have finished breeding.

Once there, they replace their old and worn out feathers and become flightless in the relative safety that the Wadden Sea offers, before returning to Britain when their moult is complete. However, in journeying to and from the Wadden Sea, Shelduck must cross the North Sea and navigate its growing number of wind farms en route.

Scientists from the British Trust for Ornithology (BTO) used state of the art tags to track four Shelduck from the Alde-Ore Estuary Special Protection Area on the Suffolk coast to the Wadden Sea. Each bird took a separate route across the North Sea, and used previously unreported stopover sites in the Dutch Wadden Sea, before continuing on to moult sites in the Helgoland Bight off the coast of Germany. Incredibly, one bird travelled back and forth between the Dutch and German Wadden Seas four times, adding an extra 1,000 km to its migratory journey.

The reasons why remain a mystery.

Ros Green, Research Ecologist at BTO and lead author on the paper, said, “Having a working knowledge of species’ is an essential first step in understanding the risks that offshore wind farms may pose to populations of Shelduck and other species. Further, our tags provided data on Shelduck flight speeds and height, giving additional vital information on the magnitude of the risks posed by developments.”

She added, “It is well known that British and Irish Shelduck populations move back and forth across the North Sea each year, but this is the first published data on the specific routes taken, how long the migration takes to complete, and how fast and high Shelduck fly.”

The four Shelduck were fitted with solar powered GPS-GSM tags, allowing BTO scientists to follow their migratory movements in great detail and in almost real time, as the GPS data are downloaded over mobile phone networks.

Incredibly, although all four birds took very different routes across the North Sea, they all ended their migration in almost exactly the same place in the Dutch Wadden Sea. During the crossing, the birds flew at speeds of up to 55 knots, and up to 354 m above the sea’s surface.

The movements recorded indicated apparent interactions with several wind farm sites, though most of these are currently only at the planning phase.

Only one data fix was recorded within an operational wind farm when a bird flew within the Egmond aan Zee wind farm.

This Shelduck was flying at a height of 85 m, which would place it at potential risk of collision with the ‘s spinning turbine blades, which sweep an area between 25 and 139 m above sea level.

Indeed, the majority of the four Shelducks’ flight occurred below 150 m above sea level, which would place them in the ‘collision risk zone’ of many of the they may pass through.

The BTO team plans to extend the tracking project and collect more data to investigate whether Shelduck are actually at risk of collision, or whether the population can adapt to this essential renewable energy infrastructure.

“Further work”, the research team add, “is also needed on tagging approaches in order to extend the deployment period beyond the main moult, and capture data on the return migration. A larger sample size of tracked birds is needed before firm conclusions on Shelduck migration can be drawn. Ideally this would include birds from a wider geographical range of British breeding sites, as well as Shelduck that breed on the continent but migrate to Britain for the winter.”



More information:
Ros M.W. Green et al, Migratory movements of British and Irish Common Shelduck Tadorna tadorna: a review of ringing data and a pilot tracking study to inform potential interactions with offshore wind farms in the North Sea, Ringing & Migration (2021). DOI: 10.1080/03078698.2019.1887670

Citation:
Migration routes of one of Britain’s largest ducks revealed for the first time (2021, March 16)
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Hexbyte Glen Cove COVID waste: Archaeologists have a role to play in informing environmental policy thumbnail

Hexbyte Glen Cove COVID waste: Archaeologists have a role to play in informing environmental policy

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The stomach contents of a Green sea turtle following a necropsy. The contents include a face mask, part of the PPE provision of the COVID-19 pandemic. Credit: Kathy Townsend

The 2020 COVID-19 pandemic is creating a viral archive, an archaeological record of history in the making. One aspect of this archive is increased environmental pollution, not least through discarded face-masks and gloves, collectively known as PPE, that characterise the pandemic.

These items of plastic waste have become symbolic of the and have now entered the archaeological record, in particular face-masks.

In the UK alone, 748 million items of PPE, amounting to 14 million items a day, were delivered to hospitals in the two or so months from 25 February 2020, comprising 360 million gloves, 158 million masks, 135 million aprons and one million gowns.

Within the context of this COVID-specific, single-use plastic and its impacts, the authors of the study argue that an archaeological perspective is uniquely placed to inform a policy-informed approach to tackling environmental .

According to the study, pollution created by the COVID-19 pandemic presents a crisis that would benefit from ‘crisis thinking’, where the aim is to define the social conditions that enable crises to be identified and for suitable action to be taken.

In particular, archaeology can contribute to much-needed solutions with its focus on the prevalence and resilience of material culture.

The study, which is published in the journal Antiquity, involved the University of York, University of Sunshine Coast and the University of Tasmania.

The stomach contents of a Green sea turtle following a necropsy. The contents include a face mask, part of the PPE provision of the COVID-19 pandemic. Credit: Kathy Townsend

Commenting on his co-author Dr. Kathy Townsend of University of the Sunshine Coast (Australia) finding a discarded face mask in the stomach of a dead Green sea turtle off Australia’s Queensland coast, Professor John Schofield from the University of York’s Department of Archaeology, said: “As archaeologists we emphasise the fact human actions have created this problem, both in general terms and here, in this specific case. Somebody wore this face mask, and then discarded it”.

“Understanding human behaviours through the material culture they leave behind is what archaeologists do, whether in prehistory, the medieval period, or yesterday. We think that this object-centred approach provides a distinct and helpful perspective on the problem of .”

“Our study speaks to the wider issues exposed by the pandemic, demonstrating one of the ways that archaeology remains relevant and useful in shaping sustainable futures.”

The authors say that archaeology has previously proved helpful in studying pandemics.

Prof Schofield added: “Our approach is less concerned with the archaeological evidence for pandemics in the past, or even the present, but more about what an archaeological lens adds to our understanding of the current and ongoing pandemic and its longer-term implications.”

The authors cite the scientific research on plastic pollution on the Galapagos islands, and how community action and assistance from non-governmental organisations, have influenced the islands’ Governing Council to change its plastic pollution policies. This includes the implementation of a waste management programme that has the highest recycling rate in Ecuador.

According to Joanna Vince, Senior Lecturer in Politics and International Relations at the University of Tasmania: “Archaeologists need to be more involved in the public debate on plastic pollution in order to inform policy decisions further. The first step is for archaeologists to increase their collaboration with policy specialists, government decision-makers and industry.”

Estelle Praet, Ph.D. student at York and co-author of the paper added “The face-mask, as material culture that became almost simultaneously symbolic worldwide, allowed us to reflect upon this building through a multi-disciplinary perspective.”



Citation:
COVID waste: Archaeologists have a role to play in informing environmental policy (2021, March 15)
retrieved 16 March 2021
from https://phys.org/news/2021-03-covid-archaeologists-role-environmental-policy.html

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Hexbyte Glen Cove Oil in the ocean photooxidizes within hours to days, new study finds thumbnail

Hexbyte Glen Cove Oil in the ocean photooxidizes within hours to days, new study finds

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Satellite image taken on May 9, 2010 of the Deepwater Horizon oil spill site in the Gulf of Mexico. Credit: MODIS on NASA’s AQUA satellite, 9 May 2010 @ 190848 UTC. Downlink and processed at the UM Rosenstiel School’s Center for Southeastern Tropical Advanced Remote Sensing (CSTARS)

A new study led by scientists at the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science demonstrates that under realistic environmental conditions oil drifting in the ocean after the DWH oil spill photooxidized into persistent compounds within hours to days, instead over long periods of time as was thought during the 2010 Deepwater Horizon oil spill. This is the first model results to support the new paradigm of photooxidation that emerged from laboratory research.

After an oil , oil droplets on the ocean surface can be transformed by a weathering process known as photooxidation, which results in the degradation of crude oil from exposure to light and oxygen into new by-products over time. Tar, a by-product of this weathering process, can remain in coastal areas for decades after a spill. Despite the significant consequences of this weathering pathway, photooxidation was not taken into account in oil spill models or the oil budget calculations during the Deepwater Horizon spill.

The UM Rosenstiel School research team developed the first oil-spill model algorithm that tracks the dose of solar radiation oil droplets receive as they rise from the deep sea and are transported at the ocean surface. The authors found that the weathering of oil droplets by solar light occurred within hours to days, and that roughly 75 percent of the photooxidation during the Deepwater Horizon oil spill occurred on the same areas where chemical dispersants were sprayed from aircraft. Photooxidized oil is known to reduce the effectiveness of aerial dispersants.

“Understanding the timing and location of this weathering process is highly consequential. said Claire Paris, a UM Rosenstiel School faculty and senior author of the study. “It helps directing efforts and resources on fresh oil while avoiding stressing the environment with chemical dispersants on oil that cannot be dispersed.”

“Photooxidized compounds like tar persist longer in the environment, so modeling the likelihood of photooxidation is critically important not only for guiding first response decisions during an oil spill and restoration efforts afterwards, but it also needs to be taken into account on risk assessments before exploration activities” added Ana Carolina Vaz, assistant scientist at UM’s Cooperative Institute for Marine and Atmospheric Studies and lead author of the study.

The study, titled “A Coupled Lagrangian-Earth System Model for Predicting Oil Photooxidation,” was published online on Feb 19, 2021 in the journal Frontiers in Marine Science. The authors of the paper include: Ana Carolina Vaz, Claire Beatrix Paris and Robin Faillettaz.



More information:
Ana C. Vaz et al, A Coupled Lagrangian-Earth System Model for Predicting Oil Photooxidation, Frontiers in Marine Science (2021). DOI: 10.3389/fmars.2021.576747

Citation:
Oil in the ocean photooxidizes within hours to days, new study finds (2021, March 13)
retrieved 15 March 2021
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Hexbyte Glen Cove Tiny bubbles making large impact on medical ultrasound imaging thumbnail

Hexbyte Glen Cove Tiny bubbles making large impact on medical ultrasound imaging

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Schematic of bubble membrane showing the influence of membrane stiffener and membrane softener in the phospholipid packing. Credit: Amin Jafari Sojahrood and Al C. de Leon

If you were given “ultrasound” in a word association game, “sound wave” might easily come to mind. But in recent years, a new term has surfaced: bubbles. Those ephemeral, globular shapes are proving useful in improving medical imaging, disease detection and targeted drug delivery. There’s just one glitch: bubbles fizzle out soon after injection into the bloodstream.

Now, after 10 years’ work, a multidisciplinary research team has built a better bubble. Their new formulations have resulted in bubbles with customizable outer shells—so small and durable that they can travel to and penetrate some of the most inaccessible areas in the human body.

The work is a collaboration between Al C. de Leon and co-authors, under the supervision of Agata A. Exner of the Department of Radiology at the Case Western Reserve University School of Medicine in Cleveland and Amin Jafari Sojahrood under the supervision of Michael Kolios of the Department of Physics at Ryerson University and the Institute for Biomedical Engineering, Science and Technology (iBEST) in Toronto. Their results were recently published in ACS Nano, in a paper entitled “Towards Precisely Controllable Acoustic Response of Shell-Stabilized Nanobubbles: High-Yield and Narrow-Dispersity”.

“The advancement can eventually lead to clearer ultrasound images,” says Kolios. “But more broadly, our joint theoretical and experimental findings provide a fundamental framework that will help establish nanobubbles for applications in biomedical imaging—and potentially into other fields, from material science to surface cleaning and mixing.”

Bubbles in Ultrasound: Shrinking Down to Nanoscale

Ultrasound is the second most used medical imaging modality in the world. As with other modalities, a patient may swallow or be injected with an agent to create image contrast, thereby making bodily structures or fluids easier to see.

With ultrasound, bubbles serve as the contrast agent. These gas-filled globes are enclosed by a phospholipid shell. Contrast is generated when ultrasound waves interact with the bubbles, causing them to oscillate and reflect soundwaves that differ significantly from waves reflected by body tissues. Bubbles are used routinely in patients to improve image quality and enhance the detection of diseases. But due to their size (about the same as red blood cells), microbubbles are confined to circulating in blood vessels, and cannot reach diseased tissue outside.

“Our research team at CWRU now engineered stable, long-circulating bubbles at the nanoscale—measuring 100-500 nm in diameter,” says Exner. “They’re so that they can even squeeze through leaky vasculature of cancerous tumours.”

With such capabilities, nanobubbles are well-suited for finer applications such as molecular imaging and targeted drug delivery. Working together with the Ryerson team, the researchers have developed a clearer understanding of the theory of how nanobubbles are visualized with ultrasound, and what imaging techniques are needed to best visualize the bubbles in the body.

Controlling Nanobubble Behaviour

Size issues aside, bubbles are also complex oscillators, exhibiting behaviours that are difficult to control. In the current work, the research team also devised a way to precisely control and predict how bubbles interact with and respond acoustically to ultrasound.

“By introducing membrane additives to our bubble formulations, we demonstrated the ability to control how stiff (or how flexible) the bubble shells become,” says de Leon. “Bubble formulations can then be customized to match the particular needs of different applications.”

For example, stiffer, stable bubble designs may last long enough to reach body tissues that are difficult to access. Softer bubbles may produce clearer ultrasound images of certain types of body tissue. Bubble oscillation could even be tweaked to increase cell permeability, potentially increasing drug delivery to diseased cells, which may in turn decrease the dosage required.

Patients, the Ultimate Beneficiaries

Having successfully demonstrated the ability to customize bubble shell properties and their interaction with sound waves, the current work has exciting implications for nanobubble potency—in both diagnostic and therapeutic applications.

Sojahrood sees many potential benefits, for biomedicine and for patients in clinic. “Compared to other imaging or treatment options, such as surgery with scalpels, bulky MRI machinery, or the risk of radioactive iodine in CT scans, ultrasound could be a lot faster, cheaper, more effective and less invasive,” he says. “By advancing through nanobubbles, we could eventually make diagnosis and treatment more available and more effective, even in more remote areas of the world, ultimately improving patient outcomes and saving more lives.”



More information:
Amin Jafari Sojahrood et al, Toward Precisely Controllable Acoustic Response of Shell-Stabilized Nanobubbles: High Yield and Narrow Dispersity, ACS Nano (2021). DOI: 10.1021/acsnano.0c09701

Citation:
Tiny bu

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Hexbyte Glen Cove Astronomers detect a black hole on the move thumbnail

Hexbyte Glen Cove Astronomers detect a black hole on the move

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Galaxy J0437+2456 is thought to be home to a supermassive, moving black hole. Credit: Sloan Digital Sky Survey (SDSS).

Scientists have long theorized that supermassive black holes can wander through space—but catching them in the act has proven difficult.

Now, researchers at the Center for Astrophysics | Harvard & Smithsonian have identified the clearest case to date of a supermassive black hole in motion. Their results are published today in the Astrophysical Journal.

“We don’t expect the majority of supermassive black holes to be moving; they’re usually content to just sit around,” says Dominic Pesce, an astronomer at the Center for Astrophysics who led the study. “They’re just so heavy that it’s tough to get them going. Consider how much more difficult it is to kick a bowling ball into motion than it is to kick a soccer ball—realizing that in this case, the ‘bowling ball’ is several million times the mass of our Sun. That’s going to require a pretty mighty kick.”

Pesce and his collaborators have been working to observe this rare occurrence for the last five years by comparing the velocities of supermassive black holes and .

“We asked: Are the velocities of the black holes the same as the velocities of the galaxies they reside in?” he explains. “We expect them to have the same velocity. If they don’t, that implies the black hole has been disturbed.”

For their search, the team initially surveyed 10 distant galaxies and the supermassive black holes at their cores. They specifically studied black holes that contained water within their accretion disks—the spiral structures that spin inward towards the black hole.

As the water orbits around the black hole, it produces a laser-like beam of radio light known as a maser. When studied with a combined network of radio antennas using a technique known as very long baseline interferometry (VLBI), masers can help measure a black hole’s velocity very precisely, Pesce says.

The technique helped the team determine that nine of the 10 supermassive black holes were at rest—but one stood out and seemed to be in motion.

Located 230 million light-years away from Earth, the black hole sits at the center of a galaxy named J0437+2456. Its mass is about three million times that of our Sun.

Using follow-up observations with the Arecibo and Gemini Observatories, the team has now confirmed their initial findings. The supermassive black hole is moving with a speed of about 110,000 miles per hour inside the galaxy J0437+2456.

But what’s causing the motion is not known. The team suspects there are two possibilities.

“We may be observing the aftermath of two supermassive black holes merging,” says Jim Condon, a radio astronomer at the National Radio Astronomy Observatory who was involved in the study. “The result of such a merger can cause the newborn black hole to recoil, and we may be watching it in the act of recoiling or as it settles down again.”

But there’s another, perhaps even more exciting possibility: the black hole may be part of a binary system.

“Despite every expectation that they really ought to be out there in some abundance, scientists have had a hard time identifying clear examples of binary supermassive black holes,” Pesce says. “What we could be seeing in the galaxy J0437+2456 is one of the black holes in such a pair, with the other remaining hidden to our radio observations because of its lack of maser emission.”

Further observations, however, will ultimately be needed to pin down the true cause of this supermassive black hole’s unusual motion.



More information:
Dominic W. Pesce et al, A Restless Supermassive Black Hole in the Galaxy J0437+2456, The Astrophysical Journal (2021). DOI: 10.3847/1538-4357/abde3d

Citation:
Astronomers detect a black hole on the move (2021, March 12)
retrieved 15 March 2021
from https://phys.org/news/2021-03-astronomers-black-hole.html

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Hexbyte Glen Cove Russia deploys giant space telescope in Lake Baikal thumbnail

Hexbyte Glen Cove Russia deploys giant space telescope in Lake Baikal

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The underwater neutrino telescope was lowered to a depth of 750-1,300 meters in Lake Baikal

Russian scientists on Saturday launched one of the world’s biggest underwater space telescopes to peer deep into the universe from the pristine waters of Lake Baikal.

The deep underwater telescope, which has been under construction since 2015, is designed to observe , the smallest particles currently known.

Dubbed Baikal-GVD, the telescope was submerged to a depth of 750-1,300 meters (2,500-4,300 feet), around four kilometres from the lake’s shore.

Neutrinos are very hard to detect and water is an effective medium for doing so.

The floating observatory consists of strings with spherical glass and stainless steel modules attached to them.

On Saturday, scientists observed the modules being carefully lowered into the freezing waters through a rectangular hole in the ice.

“A neutrino telescope measuring half a cubic kilometre is situated right under our feet,” Dmitry Naumov of the Joint Institute for Nuclear Research told AFP while standing on the lake’s frozen surface.

In several years the telescope will be expanded to measure one cubic kilometre, Naumov said.

The Baikal telescope will rival Ice Cube, a giant neutrino observatory buried under the Antarctic ice at a US research station at the South Pole, he added.

Russian scientists say the telescope is the largest neutrino detector in the Northern Hemisphere and Lake Baikal—the largest freshwater lake in the world—is ideal for housing the floating observatory.

“Of course, Lake Baikal is the only lake where you can deploy a because of its depth,” Bair Shoibonov of the Joint Institute for Nuclear Research told AFP.

“Fresh water is also important, water clarity too. And the fact that there is ice cover for two-two and a half months is also very important.”

The telescope is the result of a collaboration between scientists from the Czech Republic, Germany, Poland, Russia and Slovakia.



© 2021 AFP

Citation:
Russia deploys giant space telescope in Lake Baikal (2021, March 13)
retrieved 14 March 2021
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Hexbyte Glen Cove An unusual creature is coming out of winter's slumber. Here's why scientists are excited. thumbnail

Hexbyte Glen Cove An unusual creature is coming out of winter’s slumber. Here’s why scientists are excited.

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Researchers at the Duke Lemur Center have been changing up their care to more closely match the seasonal fluctuations they experience in the wild. Credit: David Haring, Duke Lemur Center

If you binged on high-calorie snacks and then spent the winter crashed on the couch in a months-long food coma, you’d likely wake up worse for wear. Unless you happen to be a fat-tailed dwarf lemur.

This squirrel-sized primate lives in the forests of Madagascar, where it spends up to seven months each year mostly motionless and chilling, using the minimum energy necessary to withstand the winter. While zonked, it lives off of fat stored in its tail.

Animals that hibernate in the wild rarely do so in zoos and sanctuaries, with their climate controls and year-round access to food. But now our closest hibernating relative has gone into true, deep hibernation in captivity for the first time at the Duke Lemur Center.

“They did not disappoint,” said research scientist Marina Blanco, who led the project. “Indeed, our dwarf lemurs hibernated just like their wild kin do in western Madagascar.”

The researchers say recreating some of the seasonal fluctuations of the lemurs’ native habitat might be good for the well-being of a species hardwired for hibernation, and also may yield insights into metabolic disorders in humans.

“Hibernation is literally in their DNA,” Blanco said.

Blanco has studied dwarf lemurs for 15 years in Madagascar, fitting them with tracking collars to locate them when they are hibernating in their tree holes or underground burrows. But what she and others observed in the wild didn’t square with how the animals behaved when cared for in captivity.

Captive dwarf lemurs are fed extra during the summer so they can bulk up like they do in the wild, and then they’ll hunker down and let their heart rate and temperature drop for short bouts—a physiological condition known as torpor. But they rarely stay in this suspended state for longer than 24 hours. Which got Blanco to wondering: After years in captivity, do dwarf lemurs still have what it takes to survive seasonal swings like their wild counterparts do? And what can these animals teach us about how to safely put the human body on pause too, slowing the body’s processes long enough for, say, life-saving surgery or even space travel?

To find out, Duke Lemur Center staff teamed up to build fake tree hollows out of wooden boxes and placed them in the dwarf lemurs’ indoor enclosures, as a haven for them to wait out the winter. To mimic the seasonal changes the lemurs experience over the course of the year in Madagascar, the team also gradually adjusted the lights from 12 hours a day to a more “winter-like” 9.5 hours, and lowered the thermostat from 77 degrees Fahrenheit to the low 50s.

Because dwarf lemurs are a closer genetic match to humans than other hibernators, such as bears and bats, researchers say studying their torpor may help humans safely enter and emerge from similar suspended states during surgery. Credit: Lydia Greene.

The animals were offered food if they were awake and active, and weighed every two weeks, but otherwise they were left to lie.

It worked. In the March 11 issue of the journal Scientific Reports, the researchers show for the first time that fat-tailed dwarf lemurs can hibernate quite well in captivity.

For four months, the eight lemurs in the study spent some 70% of their time in metabolic slow-motion: curled up, cool to the touch, barely moving or breathing for up to 11 days at a stretch, showing little interest in food—akin to their wild counterparts.

Now that spring is afoot in North Carolina and the temperatures are warming, the lemurs are waking up. Their first physical exams after they emerged showed them to be 22% to 35% lighter than they were at the start but otherwise healthy. Their heart rates are back up from just eight beats per minute to about 200, and their appetites have returned.

“We’ve been able to replicate their wild conditions well enough to get them to replicate their natural patterns,” said Erin Ehmke, who directs research at the center.

Females were the hibernation champs, out-stuporing the males and maintaining more of their winter weight. They need what’s left of their fat stores for the months of pregnancy and lactation that typically follow after they wake up, Blanco said.

Study co-author Lydia Greene says the next step is to use non-invasive research techniques such as metabolite analysis and sensors in their enclosures to better understand what dwarf lemurs do to prepare their bodies and eventually bounce back from months of standby mode—work that could lead to new treatments for heart attacks, strokes, and other life-threatening conditions in humans.

Blanco suspects the impressive energy-saving capabilities of these lemurs may also relate to another trait they possess: longevity. The oldest dwarf on record, Jonas, died at the Duke Lemur Center at the age of 29. The fact that dwarf lemurs live longer than non-hibernating species their size suggests that something intrinsic to their biological machinery may protect against aging.

“But until now, if you wanted to study hibernation in these primates, you needed to go to Madagascar to find them in the act,” Blanco said. “Now we can study hibernation here and do more close monitoring.”



More information:
Marina B. Blanco et al, On the modulation and maintenance of hibernation in captive dwarf lemurs, Scientific Reports (2021). DOI: 10.1038/s41598-021-84727-3

Citation:
An unusual creature is coming out of winter’s slumber. Here’s why scientists are excited. (2021, March 12)
retrieved 14 March 2021
from https://phys.org/news/2021-03-unusual-creature-winter-slumber-scientists.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduce

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