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Purported phosphine on Venus more likely to be ordinary sulfur dioxide, new study shows

An image of Venus compiled using data from the Mariner 10 spacecraft in 1974. In September, a team led by

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An image of Venus compiled using data from the Mariner 10 spacecraft in 1974.

In September, a team led by astronomers in the United Kingdom announced that they had detected the chemical phosphine in the thick clouds of Venus. The team’s reported detection, based on observations by two Earth-based radio telescopes, surprised many Venus experts. Earth’s atmosphere contains small amounts of phosphine, which may be produced by life. Phosphine on Venus generated buzz that the planet, often succinctly touted as a “hellscape,” could somehow harbor life within its acidic clouds.

Since that initial claim, other science teams have cast doubt on the reliability of the phosphine detection. Now, a team led by researchers at the University of Washington has used a robust model of the conditions within the atmosphere of Venus to revisit and comprehensively reinterpret the radio telescope observations underlying the initial phosphine claim. As they report in a paper accepted to the Astrophysical Journal and posted Jan. 25 to the preprint site arXiv, the U.K.-led group likely wasn’t detecting phosphine at all.

“Instead of phosphine in the clouds of Venus, the data are consistent with an alternative hypothesis: They were detecting sulfur dioxide,” said co-author Victoria Meadows, a UW professor of astronomy. “Sulfur dioxide is the third-most-common chemical compound in Venus’ atmosphere, and it is not considered a sign of life.”

The team behind the new study also includes scientists at NASA’s Caltech-based Jet Propulsion Laboratory, the NASA Goddard Space Flight Center, the Georgia Institute of Technology, the NASA Ames Research Center and the University of California, Riverside.

The UW-led team shows that sulfur dioxide, at levels plausible for Venus, can not only explain the observations but is also more consistent with what astronomers know of the planet’s atmosphere and its punishing chemical environment, which includes clouds of sulfuric acid. In addition, the researchers show that the initial signal originated not in the planet’s cloud layer, but far above it, in an upper layer of Venus’ atmosphere where phosphine molecules would be destroyed within seconds. This lends more support to the hypothesis that sulfur dioxide produced the signal.

Both the purported phosphine signal and this new interpretation of the data center on radio astronomy. Every chemical compound absorbs unique wavelengths of the electromagnetic spectrum, which includes radio waves, X-rays and visible light. Astronomers use radio waves, light and other emissions from planets to learn about their chemical composition, among other properties.

In 2017 using the James Clerk Maxwell Telescope, or JCMT, the U.K.-led team discovered a feature in the radio emissions from Venus at 266.94 gigahertz. Both phosphine and sulfur dioxide absorb radio waves near that frequency. To differentiate between the two, in 2019 the same team obtained follow-up observations of Venus using the Atacama Large Millimeter/submillimeter Array, or ALMA. Their analysis of ALMA observations at frequencies where only sulfur dioxide absorbs led the team to conclude that sulfur dioxide levels in Venus were too low to account for the signal at 266.94 gigahertz, and that it must instead be coming from phosphine.

In this new study by the UW-led group, the researchers started by modeling conditions within Venus’ atmosphere, and using that as a basis to comprehensively interpret the features that were seen — and not seen — in the JCMT and ALMA datasets.

“This is what’s known as a radiative transfer model, and it incorporates data from several decades’ worth of observations of Venus from multiple sources, including observatories here on Earth and spacecraft missions like Venus Express,” said lead author Andrew Lincowski, a researcher with the UW Department of Astronomy.

The team used that model to simulate signals from phosphine and sulfur dioxide for different levels of Venus’ atmosphere, and how those signals would be picked up by the JCMT and ALMA in their 2017 and 2019 configurations. Based on the shape of the 266.94-gigahertz signal picked up by the JCMT, the absorption was not coming from Venus’ cloud layer, the team reports. Instead, most of the observed signal originated some 50 or more miles above the surface, in Venus’ mesosphere. At that altitude, harsh chemicals and ultraviolet radiation would shred phosphine molecules within seconds.

“Phosphine in the mesosphere is even more fragile than phosphine in Venus’ clouds,” said Meadows. “If the JCMT signal were from phosphine in the mesosphere, then to account for the strength of the signal and the compound’s sub-second lifetime at that altitude, phosphine would have to be delivered to the mesosphere at about 100 times the rate that oxygen is pumped into Earth’s atmosphere by photosynthesis.”

The researchers also discovered that the ALMA data likely significantly underestimated the amount of sulfur dioxide in Venus’ atmosphere, an observation that the U.K.-led team had used to assert that the bulk of the 266.94-gigahertz signal was from phosphine.

“The antenna configuration of ALMA at the time of the 2019 observations has an undesirable side effect: The signals from gases that can be found nearly everywhere in Venus’ atmosphere — like sulfur dioxide — give off weaker signals than gases distributed over a smaller scale,” said co-author Alex Akins, a researcher at the Jet Propulsion Laboratory.

This phenomenon, known as spectral line dilution, would not have affected the JCMT observations, leading to an underestimate of how much sulfur dioxide was being seen by JCMT.

“They inferred a low detection of sulfur dioxide because of that artificially weak signal from ALMA,” said Lincowski. “But our modeling suggests that the line-diluted ALMA data would have still been consistent with typical or even large amounts of Venus sulfur dioxide, which could fully explain the observed JCMT signal.”

“When this new discovery was announced, the reported low sulfur dioxide abundance was at odds with what we already know about Venus and its clouds,” said Meadows. “Our new work provides a complete framework that shows how typical amounts of sulfur dioxide in the Venus mesosphere can explain both the signal detections, and non-detections, in the JCMT and ALMA data, without the need for phosphine.”

With science teams around the world following up with fresh observations of Earth’s cloud-shrouded neighbor, this new study provides an alternative explanation to the claim that something geologically, chemically or biologically must be generating phosphine in the clouds. But though this signal appears to have a more straightforward explanation — with a toxic atmosphere, bone-crushing pressure and some of our solar system’s hottest temperatures outside of the sun — Venus remains a world of mysteries, with much left for us to explore.

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Additional co-authors are David Crisp at the JPL, Edward Schwieterman at UC Riverside, Giada Arney and Shawn Domagal-Goldman at the Goddard Space Flight Center, UW researcher Michael Wong, Paul Steffes at Georgia Tech and Niki Parenteau at NASA Ames. The research was funded by the NASA Astrobiology Program and performed at the NExSS Virtual Planetary Laboratory.

For more information, contact Meadows at [email protected], Akins at [email protected] and Lincowski at [email protected]

Grant number: 80NSSC18K0829

Source: https://bioengineer.org/purported-phosphine-on-venus-more-likely-to-be-ordinary-sulfur-dioxide-new-study-shows/

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Pioneering chemistry approach could lead to more robust soft electronics

Credit: Udit Chakraborty, Cornell University RESEARCH TRIANGLE PARK, N.C. — A new approach to studying conjugated polymers made it possible

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RESEARCH TRIANGLE PARK, N.C. — A new approach to studying conjugated polymers made it possible for an Army-funded research team to measure, for the first time, the individual molecules’ mechanical and kinetic properties during polymerization reaction. The insights gained could lead to more flexible and robust soft electronic materials, such as health monitors and soft robotics.

Conjugated polymers are essentially clusters of molecules strung along a backbone that can conduct electrons and absorb light. This makes them a perfect fit for creating soft optoelectronics, such as wearable electronic devices; however, as flexible as they are, these polymers are difficult to study in bulk because they aggregate and fall out from solution.

“Conjugated polymers are a fascinating class of materials due to their inherent optical and electronic properties which are dictated by their polymer structure,” said Dr. Dawanne Poree, program manager, U.S. Army Combat Capabilities Development Command, known as DEVCOM, Army Research Laboratory. “These materials are highly relevant to a number of applications of interest to Army and DoD including portable electronics, wearable devices, sensors, and optical communication systems. To date, unfortunately, it has been difficult to develop conjugated polymers for targeted applications due to a lack of viable tools to study and correlate their structure-property relationships.”

With Army funding, researchers at Cornell University employed an approach they pioneered on other synthetic polymers, called magnetic tweezers, that allowed them to stretch and twist individual molecules of the conjugated polymer polyacetylene. The research was published in the journal Chem.

“Through the use of novel single-molecule manipulation and imaging approaches, this work provided the first observations of single-chain behaviors in conjugated polymers which lays the foundation for the rational design and processing of these materials to enable widespread application,” Poree said.

Previous efforts to address the solubility of conjugated polymers have often relied upon chemical derivatization, in which the structures are modified with functional groups of atoms. However, that approach can affect the polymer’s innate properties.

“The conjugated polymer is really a prototype,” said Dr. Peng Chen, the Peter J.W. Debye professor of chemistry and chemical biology at Cornell. “You always modify it to tailor it for applications. We are hoping everything we measured – the fundamental properties of synthesis kinetics, the mechanical property – become benchmark numbers for people to think about other polymers of the same category.”

In 2017, Chen’s group was the first to use the magnetic tweezers measurement technique to study living polymerization, visualizing it at the single-molecule level. The technique had already been used in the biophysics field for studying DNA and proteins, but no one had successfully extended it to the realm of synthetic polymers.

The process works by affixing one end of a polymer strand to a glass coverslip and the other end to a tiny magnetic particle. The researchers then use a magnetic field to manipulate the conjugated polymer, stretching or twisting it, and measuring the response of a single polymer chain that grows.

The amounts are so small, they stay soluble in solution, the way bulk amounts normally would not.

The team measured how long chains of conjugated polymers, which consist of hundreds of thousands of monomer units, grow in real time. They discovered these polymers add a new monomer per second, a much faster growth than their nonconjugated analogs.

“We found that while growing in real time, this polymer forms conformational entanglements,” Chen said. “All polymers we have studied form conformational entanglements, but for this conjugated polymer this conformational entanglement is looser, allowing it to grow faster.”

By pulling and stretching individual conjugated polymers, so-called force extension measurements, the researchers were able to assess their rigidity and better understand how they can bend in different directions while remaining conjugated and retaining electron conductivity.

They also discovered the polymers displayed diverse mechanical behaviors from one individual chain to the next-behaviors that had been predicted by theory but never observed experimentally.

The findings highlight both the uniqueness of conjugated polymers for a range of applications as well as the strength of using a single-molecule manipulation and imaging technique on synthetic materials.

“Now we have a new way to study how these conjugated polymers are made chemically and what is the fundamental mechanical property of this type of material,” Chen said. “We can study how these fundamental properties change when you start tailoring them for application purposes. Maybe you can make it more mechanically flexible and make the polymer longer, or adjust the synthesis condition to either synthesize the polymer in a faster or slower way.”

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Visit the laboratory’s Media Center to discover more Army science and technology stories

As the Army’s national research laboratory, ARL is operationalizing science to achieve transformational overmatch. Through collaboration across the command’s core technical competencies, we lead in the discovery, development and delivery of the technology-based capabilities required to make Soldiers more successful at winning the nation’s wars and come home safely. DEVCOM Army Research Laboratory is an element of the U.S. Army Combat Capabilities Development Command. DEVCOM is a major subordinate command of the Army Futures Command.

Source: https://bioengineer.org/pioneering-chemistry-approach-could-lead-to-more-robust-soft-electronics/

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What factors put Philippine birds at risk of extinction?

Credit: Ça?an ?ekercio?lu The lush forests and more than 7,000 islands of the Philippines hold a rich diversity of life,

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The lush forests and more than 7,000 islands of the Philippines hold a rich diversity of life, with 258 bird species who live nowhere but the Philippine archipelago. A new study from University of Utah researchers suggests that, due to deforestation and habitat degradation, more bird species may be endangered that previously thought – including species that may not have been discovered yet. The study is published in Frontiers in Ecology and Evolution.

“Our study provides a roadmap for not only which species may warrant heightened conservation attention,” says Kyle Kittelberger, a doctoral student in the University of Utah School of Biological Sciences, “but which traits a species may have that can help inform if it may likely be more at risk of extinction.”

Birds of the Philippines

Located in Southeast Asia, the Philippines is considered a global biodiversity hotspot and one of the most biodiverse countries in the world, hosting nearly 600 bird species. A high proportion of the wildlife is endemic to the country, meaning that it is found nowhere else. The Philippines also hosts some of the highest richness of species recently identified as distinct from other closely related species, showing that scientists still have much to learn about the Philippine ecosystems.

Within the last decade the number of endemic species has risen from 172 to 258. This increase of 86 endemic species is more than all the endemic bird species in China (67) or India (75) and more than any country in South America or Africa.

Çağan Şekercioğlu, an associate professor in the School of Biological Sciences who has done ornithological field work in over 90 countries on all continents cannot forget his first visit to the islands.

“When I first visited the Philippines in 2008, I was awestruck by the diversity and especially the endemism of its avifauna but also greatly depressed by the rapid loss of habitat,” he says. Excursions into the field took hours due to extensive deforestation. “While looking for rare forest birds in the lowlands of Mindanao, we were literally trying to keep ahead of the loggers that were cutting down century-old rainforest trees within a couple hundred meters of us,” he adds. Despite that, in 13 days he saw 161 bird species he had never seen before- and still has 163 bird species to go.

Deforestation, habitat degradation and wildlife exploitation, however, threatens that biodiversity. Southeast Asia, the authors write, is forecast to lose over a third of its biodiversity over the next century. The Philippines in particular ranks 8th in the world for the number of globally threatened bird species.

“There is a pressing need to assess what traits make some species more at risk of extinction than others,” Kittelberger says, and use this understanding to help inform conservation efforts.”

Traits of threatened birds

To understand the status of Philippine birds, the researchers first determined the bird traits most predictive of extinction risk by correlating bird species’ ecological and life history traits, including body mass, diet, elevation range, and clutch size (the number of eggs laid in a nesting season) with their conservation status. A species endemic to the Philippines was significantly more likely to face an extinction risk, they found. Narrow elevation ranges, dependence on forests and high body mass also put birds at risk for extinction.

Then the researchers turned around and evaluated Philippine birds’ expected conservation status using those traits, comparing predicted conservation status with the IUCN Red List conservation designations. They found that 84 species were predicted to be in worse shape than their Red List designation, with 14 species predicted to be globally threatened (i.e. vulnerable, endangered, or critically endangered) that aren’t currently classified as such.

“We predicted that the Philippine Serpent-eagle and Writhed Hornbill, two species that are not currently recognized as being globally threatened, are respectively endangered and critically endangered,” Kittelberger says. “We also predicted that the Palawan Peacock-pheasant, Calayan Rail and Philippine Eagle-owl, three species currently recognized internationally as being vulnerable, are likely endangered species. All these birds therefore warrant heightened conservation attention as they may be more threatened than currently believed.”

Lost before they’re found

Among the 84 species predicted to be more threatened, 12 were recently recognized as separate species, and three of those were predicted to be “vulnerable.”

“The Philippines have a very high level of endemism and it is currently estimated that there are twice as many bird species in the Philippines that have not yet been split and officially recognized, so there is a real risk of losing species before they are described,” Kittelberger says.

Kittelberger says that their research can be applied broadly to assess the conservation status of birds throughout the region.

“The most important thing that the Philippines can do to protect birds,” Kittelberger says, “is to address the high levels of deforestation, habitat degradation, and wildlife exploitation, and to increase land protection for wildlife and increase funding for conservation efforts.”

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Find the full study here.

Co-authors also include Montague H. C. Neate-Clegg, J. David Blount and Çağan Şekercioğlu of the U’s School of Biological Sciences, Mary Rose C. Posa of the California Botanic Garden and John McLaughlin of the University of California, Santa Barbara. The study was supported by the Christensen Fund.

Within the last decade the number of endemic species has risen from 172 to 258. This increase of 86 endemic species is more than all the endemic bird species in China (67) or India (75) and more than any country in South America or Africa.

Source: https://bioengineer.org/what-factors-put-philippine-birds-at-risk-of-extinction/

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Stem cells may hold a key to developing new vaccines against COVID-19

Coronavirus activates a stem cell-mediated defense mechanism that reactivates dormant TB in a mouse model and has implications for developing

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Coronavirus activates a stem cell-mediated defense mechanism that reactivates dormant TB in a mouse model and has implications for developing new vaccines and avoiding a global TB pandemic, report investigators in The American Journal of Pathology

Philadelphia, June 16, 2021 – The SARS-CoV-2 virus that causes COVID-19 may have the ability to reactivate dormant tuberculosis (TB). In a novel study scientists report in The American Journal of Pathology that infection with a specific coronavirus strain reactivated dormant Mycobacterium tuberculosis (MTB) in mice. This knowledge may help to develop new vaccines for COVID-19 and avoid a potential global tuberculosis epidemic.

The COVID-19 pandemic caused by the SARS-CoV-2 virus demonstrates the ability of an emerging virus to affect masses and strain and disrupt the workings of modern healthcare systems around the world. A significant number of infected COVID-19 individuals have recovered. However, a possible host defense or antiviral mechanism against the virus is yet to be identified. There are concerns that in the long-term, the virus might activate dormant bacterial infections such as TB in select infected individuals, as alarmingly, TB is already present in one quarter of the world population. Viral infections such as the influenza virus or SARS-CoV-1 are known to cause transient immune suppression that leads to reactivation of dormant bacterial infection. The highest death rate during the Spanish flu pandemic of 1918 was in patients with TB, and patients with TB or multidrug-resistant TB had a worse prognosis than others during the influenza A (H1N1) pandemic in 2009.

“There is an urgent need to study the association of COVID-19 with dormant TB reactivation to avoid a potential global TB pandemic,” explained lead investigator Bikul Das, MD, PhD, Department of Stem Cell and Infectious Diseases, KaviKrishna Laboratory, Guwahati Biotech Park, Indian Institute of Technology, Guwahati, India; and Department of Stem Cell and Infection, Thoreau Lab for Global Health, University of Massachusetts, Lowell, MA, USA. “It is important to understand the host defense mechanism against this disease to develop a better vaccine and/or treatment. We therefore postulated that, similar to bacteria, adult stem cells may also exhibit an altruistic defense mechanism to protect their niche against external threat.”

Investigators studied the coronavirus strain murine hepatitis virus-1 (MHV-1) infection in the lung in a mouse model (dMtb) of mesenchymal stem cell (MSC)-mediated MTB dormancy. This showed 20-fold lower viral loads than the dMtb-free control mice by the third week of viral infection and a six-fold increase of altruistic stem cells (ASCs), thereby enhancing the defense. Tuberculosis was reactivated in the dMtb mice, suggesting that dormant TB bacteria hijack these ASCs to replicate in the lung to cause pulmonary TB. Results suggest that these ASCs are transient (they expand for two weeks and then undergo apoptosis or cellular suicide) and exhibit antiviral activities against MHV-1 by secreting soluble factors.

“These findings are important because they reveal a novel ASC defense mechanism against mouse coronavirus infection, which could be used to develop novel therapeutic approaches against COVID-19,” noted Bikul Das. “The finding of TB reactivation in a stem cell-mediated Mtb dormancy mouse model during MHV-1 coronavirus infection indicates that in the long-term, post-pandemic, the SARS-CoV-2 virus might activate dormant bacterial infections. This is a significant finding considering the current coronavirus pandemic, where many individuals in India and other developing countries with dormant TB infection may see an increase in active TB cases post COVID-19. The ASC-mediated defense mechanism may be targeted to develop vaccines against viral infections and avoid a potential global TB pandemic.”

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Background notes

This study of stem cell altruism was inspired by the Indian Vedantic Philosophical theory of altruistic behavior, which was referred to in the poem “Fire of Golden Nail” written by Vedic philosopher and poet Krishna Ram Das of Kamrupa, India, noted the study’s authors. Poet Krishna Ram Das conceptualized the idea while undergoing surgery for throat cancer and initiated the KaviKrishna Foundation to test his idea through vigorous scientific research.

“Proving altruism in mammalian cell biology is a challenging task, as we faced years of resistance from colleagues,” commented Bikul Das. “Altruism is about group selection, which is very challenging to demonstrate at the molecular level. However, the idea of altruism that we are describing here is the philosophical view of Vedic Jiva Upakarvada (Vedic altruism), a part of Vedantic thought that states that during stress, the living organism acquires a higher state, known as ‘Avatar.’ The mandate of the KaviKrishna laboratory is to take this philosophical view forward to modern biology, specifically to develop a philosophical and social theory on global health.

First author Lekhika Pathak, PhD student at the KaviKrishna Lab, GBP, IIT-Guwahati, India, commented: “I joined the laboratory hoping to further ASC research exploiting the model of MHV-1-infected stem cell-mediated Mtb dormancy. Our research findings now may provide a novel approach to understand the interaction between two pathogens, coronavirus and M. tuberculosis, both of which are major threats to global health.”

Co-investigator Herman Yeger, PhD, of the Department of Pediatric Laboratory Medicine, Hospital for Sick Children, Toronto, Ontario, Canada, added: “I commend Bikul Das for being innovative in transforming a piece of Indian philosophy into a testable biological experiment on altruism. Now that we have obtained convincing data on the identification of ASC and their defense against coronavirus, we hope to develop a novel approach to tackle this growing pandemic.”

https://www.elsevier.com/about/press-releases/research-and-journals/stem-cells-may-hold-a-key-to-developing-new-vaccines-against-covid-19

Source: https://bioengineer.org/stem-cells-may-hold-a-key-to-developing-new-vaccines-against-covid-19/

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