Daily Archives: 10 Nov 2020

Medicine

A Viable Vaccine For Tough Tumors (Medicine)

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Biomaterial-based cancer vaccine combines chemo and immunotherapy to treat triple-negative breast cancer in mice.

Patients with cancer have multiple treatment options available to them today, but each has its drawbacks. Chemotherapy kills rapidly dividing cancer cells, but it also damages healthy cells in the body and often does not effectively prevent tumor metastasis or disease recurrence. Immunotherapies avoid those problems by acting on a patient’s immune system to generate a sustained anti-cancer response, but frequently have trouble accessing tumors due to the immunosuppressive local environment that tumors create.

Dendritic cells, like the one seen here in yellow, pick up antigens from tumor cells and carry them to the lymph nodes and spleen, where they are presented to T cells that mount an immune attack against the tumor. Credit: Wyss Institute at Harvard University.

Now, a new, best-of-both-worlds approach packages the cancer-killing power of chemotherapy and the long-term efficacy of immunotherapy into a biomaterial-based cancer vaccine that can be injected adjacent to a tumor site. When mice with aggressive triple-negative breast cancer (TNBC) were given the vaccine, 100% of them survived a subsequent injection of cancer cells without relapsing. This research is reported in Nature Communications.

“Triple-negative breast cancer does not stimulate strong responses from the immune system, and existing immunotherapies have failed to treat it. In our system, the immunotherapy attracts numerous immune cells to the tumor while the chemotherapy produces a large number of dead cancer cell fragments that the immune cells can pick up and use to generate an effective tumor-specific response,” said co-first author Hua Wang, Ph.D., a former Postdoc and Technology Development Fellow at Harvard’s Wyss Institute for Biologically Inspired Engineering and John A. Paulson School for Engineering and Applied Sciences (SEAS) who is now an Assistant Professor in the Department of Materials Science and Engineering at University of Illinois, Urbana-Champaign.

Personalized vaccines without the wait

First developed in 2009, the injectable cancer vaccine has shown great promise in treating multiple types of cancer in mice, and has been explored in clinical trials for treating melanoma at Dana Farber Cancer Institute. In the original formulation of the vaccine, molecules found in cancerous cells called tumor-associated antigens (TAAs) were incorporated together with adjuvants inside the aspirin-sized scaffold so that arriving dendritic cells could recognize them as “foreign” and mount an immune response targeted against the tumor. These TAAs can be isolated from harvested tumors or identified by sequencing the genome of cancerous cells and subsequently manufactured, but both of these processes to create personalized cancer vaccines can be long, tedious, and expensive.

“One of the critical limiting factors in the development of cancer vaccines is the selection of TAAs, because currently we only have a very small library of known antigens for a few specific tumor cell lines, and it’s difficult to predict which can mount an effective immune response,” said co-first author Alex Najibi, a graduate student in the lab of Wyss Core Faculty member David Mooney. “Implanting chemotherapy drugs inside the vaccine scaffold creates a burst of cancer cell death that releases TAAs directly from the tumor to the dendritic cells, bypassing the long and costly antigen development process.”

Wang, Najibi, and their colleagues set out to apply this new cancer vaccine tactic to TNBC, a disease in which the tumors aggressively suppress immune activity in their local area, limiting the efficacy of immunotherapy. The team first loaded their alginate hydrogel scaffold with a protein molecule called Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF). GM-CSF stimulates the development and concentration of dendritic cells, which take up antigens from tumors and other invaders and present them to T cells in the lymph nodes and spleen to initiate an immune response. They also added the chemotherapy drug doxorubicin (Dox) attached to a peptide called iRGD. iRGD is known to penetrate tumors, and helps target the Dox to tumors upon release.

When mice with TNBC tumors were injected with the new vaccine, those that received a scaffold loaded with GM-CSF and the Dox-iRGD conjugate showed significantly better penetration of the drug into tumors, increased cancer cell death, and fewer metastatic tumors in the lungs than those that received gels containing Dox conjugated to a scrambled peptide molecule, unmodified Dox, or were untreated. Analysis of the scaffolds showed that they had accumulated a large number of dendritic cells, indicating that both the immunotherapy and chemotherapy components of the vaccine were active.

Encouraged by these results, the team then experimented with adding a third component to the vaccine called CpG, a synthetic bacterial DNA sequence that is known to enhance immune responses. Mice that received vaccines with this addition displayed significantly slower tumor growth and longer survival times than mice that received vaccines without it. To evaluate the strength and specificity of the immune response generated by this three-part vaccine, the researchers extracted and analyzed cells from the animals’ lymph nodes and spleens. Strikingly, 14% of the T cells taken from lymph nodes reacted against the tumor cells, indicating that they had been “trained” by the dendritic cells to target the cancer, compared with only 5.3% of the mice that received the two-part vaccine and 2.4% of the T cells from untreated mice. In addition, giving a “booster” dose of the vaccine 12 days post-injection increased their survival time even further.

Localized action, long-term protection

While these results revealed the vaccine’s effect on activating the immune system, the team also wanted to understand how it affected the local tumor microenvironment. Analysis of the vaccines and their nearby tumors revealed that cells in tumors treated with gels containing GM-CSF, Dox-iRGD, and CpG had an increased amount of the protein calreticulin on their surfaces, which is an indicator of cell death. Mice that received the three-part vaccine also displayed higher numbers of pro-inflammatory macrophages: white blood cells that are associated with improved anticancer activity and longer survival.

The researchers also discovered that their treatment caused an increase in the expression of the cell-surface protein PD-L1 on tumor cells, which is used by cancer to evade immune detection. They had a hunch that co-administering an anti-PD-1 checkpoint inhibitor treatment that blocks this immune evasion with their vaccine would increase its effectiveness. They implanted the three-part vaccine into mice, then injected anti-PD-1 separately. Mice treated with the combination of gel vaccine and anti-PD-1 showed significantly reduced tumor size and number, and survived for a median of 40 days compared to 27 days for untreated mice and 28 days for mice that received anti-PD-1 alone. This synergy suggested that the vaccine might best be used in combination with checkpoint inhibitor therapies.

To imitate how the cancer vaccine might be administered to human patients, the team tested its ability to prevent cancer recurrence after a primary tumor is removed. They surgically excised TNBC tumors from mice, then injected either their three-part hydrogel vaccine or a liquid vaccine containing all the components in a suspension near the original tumor site. Both treated groups had significantly lower tumor recurrence, but the gel vaccine produced significantly slower tumor growth and improved survival. Mice were then re-challenged with an injection of cancer cells and, strikingly, 100% of the mice that had received the gel vaccine survived with no metastasis, while all of the untreated mice succumbed to the disease.

“The ability of this vaccine to elicit potent immune responses without requiring the identification of patient-specific antigens is a major advantage, as is the ability of local chemotherapy delivery to bypass the severe side effects of systemic chemotherapy, the only treatment currently available for the disease,” said corresponding author Mooney, Ph.D., who leads the Immuno-Materials platform at the Wyss Institute and is also the Robert P. Pinkas Family Professor of Bioengineering at SEAS. “Not only does this vaccine activate dendritic cells with tumor-specific TAAs in situ, it also reshapes the tumor microenvironment to allow the immune system greater access to the tumor, and creates an immune memory that prevents further recurrences.”

The team is continuing to explore the combination of chemotherapy with cancer vaccines, and hopes to improve their antitumor efficacy for other difficult-to-treat tumor models. The team hopes that future studies to better understand and optimize the system will allow it to move into preclinical trials and, eventually, human patients.

“The team’s newest version of their cancer vaccine is a novel multifunctional anticancer therapy that offers new hope for the treatment of a wide range of cancers. It is essentially an entirely new form of combination chemotherapy that can be administered through a single injection and potentially offer greater efficacy with much lower toxicity than conventional treatments used today,” said Wyss Institute Founding Director Don Ingber, M.D., Ph.D. Ingber is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School and the Vascular Biology Program at Boston Children’s Hospital, as well as Professor of Bioengineering at SEAS.

References : Wang, H., Najibi, A.J., Sobral, M.C. et al. Biomaterial-based scaffold for in situ chemo-immunotherapy to treat poorly immunogenic tumors. Nat Commun 11, 5696 (2020). https://doi.org/10.1038/s41467-020-19540-z https://www.nature.com/articles/s41467-020-19540-z

Provided by WYSS Institute For Biologically Inspired Engineering At Harvard

Geology, Planetary Science

Radioactive Elements may be Crucial to the Habitability of Rocky Planets (Geology /Planetary Science)

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Earth-size planets can have varying amounts of radioactive elements, which generate internal heat that drives a planet’s geological activity and magnetism.

The amount of long-lived radioactive elements incorporated into a rocky planet as it forms may be a crucial factor in determining its future habitability, according to a new study by an interdisciplinary team of scientists at UC Santa Cruz.

These illustrations show three versions of a rocky planet with different amounts of internal heating from radioactive elements. The middle planet is Earth-like, with plate tectonics and an internal dynamo generating a magnetic field. The top planet, with more radiogenic heating, has extreme volcanism but no dynamo or magnetic field. The bottom planet, with less radiogenic heating, is geologically ‘dead,’ with no volcanism. ©Illustrations by Melissa Weiss.

That’s because internal heating from the radioactive decay of the heavy elements thorium and uranium drives plate tectonics and may be necessary for the planet to generate a magnetic field. Earth’s magnetic field protects the planet from solar winds and cosmic rays.

Convection in Earth’s molten metallic core creates an internal dynamo (the “geodynamo”) that generates the planet’s magnetic field. Earth’s supply of radioactive elements provides more than enough internal heating to generate a persistent geodynamo, according to Francis Nimmo, professor of Earth and planetary sciences at UC Santa Cruz and first author of a paper on the new findings, published November 10 in Astrophysical Journal Letters.

“What we realized was that different planets accumulate different amounts of these radioactive elements that ultimately power geological activity and the magnetic field,” Nimmo explained. “So we took a model of the Earth and dialed the amount of internal radiogenic heat production up and down to see what happens.”

What they found is that if the radiogenic heating is more than the Earth’s, the planet can’t permanently sustain a dynamo, as Earth has done. That happens because most of the thorium and uranium end up in the mantle, and too much heat in the mantle acts as an insulator, preventing the molten core from losing heat fast enough to generate the convective motions that produce the magnetic field.

With more radiogenic internal heating, the planet also has much more volcanic activity, which could produce frequent mass extinction events. On the other hand, too little radioactive heat results in no volcanism and a geologically “dead” planet.

“Just by changing this one variable, you sweep through these different scenarios, from geologically dead to Earth-like to extremely volcanic without a dynamo,” Nimmo said, adding that these findings warrant more detailed studies.

“Now that we see the important implications of varying the amount of radiogenic heating, the simplified model that we used should be checked by more detailed calculations,” he said.

A planetary dynamo has been tied to habitability in several ways, according to Natalie Batalha, a professor of astronomy and astrophysics whose Astrobiology Initiative at UC Santa Cruz sparked the interdisciplinary collaboration that led to this paper.

“It has long been speculated that internal heating drives plate tectonics, which creates carbon cycling and geological activity like volcanism, which produces an atmosphere,” Batalha explained. “And the ability to retain an atmosphere is related to the magnetic field, which is also driven by internal heating.”

Coauthor Joel Primack, a professor emeritus of physics, explained that stellar winds, which are fast-moving flows of material ejected from stars, can steadily erode a planet’s atmosphere if it has no magnetic field.

“The lack of a magnetic field is apparently part of the reason, along with its lower gravity, why Mars has a very thin atmosphere,” he said. “It used to have a thicker atmosphere, and for a while it had surface water. Without the protection of a magnetic field, much more radiation gets through and the surface of the planet also becomes less habitable.”

Primack noted that the heavy elements crucial to radiogenic heating are created during mergers of neutron stars, which are extremely rare events. The creation of these so-called r-process elements during neutron-star mergers has been a focus of research by coauthor Enrico Ramirez-Ruiz, professor of astronomy and astrophysics.

“We would expect considerable variability in the amounts of these elements incorporated into stars and planets, because it depends on how close the matter that formed them was to where these rare events occurred in the galaxy,” Primack said.

Astronomers can use spectroscopy to measure the abundance of different elements in stars, and the compositions of planets are expected to be similar to those of the stars they orbit. The rare earth element europium, which is readily observed in stellar spectra, is created by the same process that makes the two longest-lived radioactive elements, thorium and uranium, so europium can be used as a tracer to study the variability of those elements in our galaxy’s stars and planets.

Astronomers have obtained europium measurements for many stars in our galactic neighborhood. Nimmo was able use those measurements to establish a natural range of inputs to his models of radiogenic heating. The sun’s composition is in the middle of that range. According to Primack, many stars have half as much europium compared to magnesium as the sun, and many stars have up to two times more than the sun.

The importance and variability of radiogenic heating opens up many new questions for astrobiologists, Batalha said.

“It’s a complex story, because both extremes have implications for habitability. You need enough radiogenic heating to sustain plate tectonics but not so much that you shut down the magnetic dynamo,” she said. “Ultimately, we’re looking for the most likely abodes of life. The abundance of uranium and thorium appear to be key factors, possibly even another dimension for defining a Goldilocks planet.”

Using europium measurements of their stars to identify planetary systems with different amounts of radiogenic elements, astronomers can start looking for differences between the planets in those systems, Nimmo said, especially once the James Webb Space Telescope is deployed. “The James Webb Space Telescope will be a powerful tool for the characterization of exoplanet atmospheres,” he said.

References : http://dx.doi.org/10.3847/2041-8213/abc251

Provided by University of California Santa Cruz

Neuroscience

Printable Ink Guides Cell Growth, Offers Nerve Injury Hope (Neuroscience)

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Bioconductive ink uses body’s own electricity to guide nerve cell growth.

Researchers have developed a neuron-growing ink that uses the body’s own electrical signals to precisely guide the growth of nerve cells.

The bioconductive ink can be printed in lines to direct where neurons grow, cracking a major challenge in the emerging field of nerve engineering.

A magnified image show neurons growing in a line along the printable bioconductive ink. ©RMIT University

The team of researchers from Australia, India and Bangladesh have tested the ink on a biocompatible scaffold, with their promising lab results published in the journal RSC Advances.

Lead author, RMIT University’s Dr Shadi Houshyar, said concentrating the growth of nerve cells in precisely ordered lines was essential to be able to reconnect nerves and heal traumatic nerve injuries.

“Nerve cells need to be meticulously guided to regrow between the broken ends of a nerve – if they just build up anywhere they will cause more pain or sensory problems,” Houshyar said.

“With our bioconductive ink, we can concentrate the neuron growth where we need it.

“Our research is in early stages but with further development, we hope one day to enable damaged nerves to be fully reconnected, to improve the lives of millions of people worldwide.”

Currently, there are limited options for rebuilding function when an injury results in large peripheral nerve gaps.

Nerve grafts, where surgeons harvest nerves from elsewhere in the body to bridge across a gap, can lead to complications including painful neuromas, misalignment of neural cell growth and injury at the harvest site.

Although emerging alternative techniques such as artificial nerve guides exist, they often fail to achieve full functional or sensory recovery because they don’t properly replicate nerve tissue.

Powering nerve cell regeneration

The new nerve-regenerating ink combines the neurotransmitter dopamine – known to help nerve cell survival – with a conductive carbon nanofibre and polymer.

The nanofibre and polymer enables the controlled release of dopamine from the ink, supporting the survival of developing neurons for longer.

A magnified image shows neurons growing in all directions in the absence of the printable ink. ©RMIT University

Because it is conductive, the nanofibre can also harness the power of bioelectricity – the electrical signals generated by the nervous system that play a key role in maintaining biological function and can accelerate wound healing.

“Using conductive materials allows free movement of electrons, stimulates cell growth and helps connect injured neural tissue,” Houshyar, a Vice-Chancellor’s Research Fellow in the RMIT School of Engineering, said.

As part of the research, the team also developed a biocompatible scaffold, so the ink could be printed in lines and tested with human cells.

The study found the printed lines supported neural cell attachment and migration – both important for nerve regeneration.

Cell differentiation was also boosted, with the neural cells becoming more specialised as they grew along the lines.

Neurons growing in a line along the bioconductive ink (left) and growing in all directions in the absence of the printable ink (right). ©RMIT University

“This supports proper communication with other neurons, which is promising for the establishment of neural circuits for sensory and motor processing – offering hope the technology could lead to a real recovery of nerve function,” Houshyar said.

The next stage for the research is testing the ink and scaffold in pre-clinical animal trials, as well as exploring other applications.

“Our end goal is a nerve engineering solution that can direct the growth of the right nerve cells in the right places,” she said.

“We’re also keen to investigate how we can expand the potential uses of this technology, for speeding up wound healing and improving patient recovery.”

References: Shadi Houshyar, Mamatha M. Pillai, Tanushree Shah et al., “Three-dimensional directional nerve guide conduits fabricated by dopamine-functionalized conductive carbon nanofibre-based nanocomposite ink printing”, RSC Advances, 2020. https://pubs.rsc.org/en/content/articlelanding/2020/ra/d0ra06556k#!divAbstract

Provided by RMIT University

Astronomy

The Universe Is Getting Hot, Hot, Hot, A New Study Suggests (Astronomy)

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Temperature has increased about 10 times over the last 10 billion years.

The universe is getting hotter, a new study has found.

The study, published Oct. 13 in the Astrophysical Journal, probed the thermal history of the universe over the last 10 billion years. It found that the mean temperature of gas across the universe has increased more than 10 times over that time period and reached about 2 million degrees Kelvin today — approximately 4 million degrees Fahrenheit.

A new study has found that the universe is getting hotter. Credit: Greg Rakozy on Unsplash.

“Our new measurement provides a direct confirmation of the seminal work by Jim Peebles — the 2019 Nobel Laureate in Physics — who laid out the theory of how the large-scale structure forms in the universe,” said Yi-Kuan Chiang, lead author of the study and a research fellow at The Ohio State University Center for Cosmology and AstroParticle Physics.

The large-scale structure of the universe refers to the global patterns of galaxies and galaxy clusters on scales beyond individual galaxies. It is formed by the gravitational collapse of dark matter and gas.

“As the universe evolves, gravity pulls dark matter and gas in space together into galaxies and clusters of galaxies,” Chiang said. “The drag is violent — so violent that more and more gas is shocked and heated up.”

The findings, Chiang said, showed scientists how to clock the progress of cosmic structure formation by “checking the temperature” of the universe.

The researchers used a new method that allowed them to estimate the temperature of gas farther away from Earth — which means further back in time — and compare them to gases closer to Earth and near the present time. Now, he said, researchers have confirmed that the universe is getting hotter over time due to the gravitational collapse of cosmic structure, and the heating will likely continue.

To understand how the temperature of the universe has changed over time, researchers used data on light throughout space collected by two missions, Planck and the Sloan Digital Sky Survey. Planck is the European Space Agency mission that operates with heavy involvement from NASA; Sloan collects detailed images and light spectra from the universe.

As the universe evolves, matter concentrations are surrounded by gas halos getting hotter and bigger. (Credit: D. Nelson / Illustris Collaboration)

They combined data from the two missions and evaluated the distances of the hot gases near and far via measuring redshift, a notion that astrophysicists use to estimate the cosmic age at which distant objects are observed. (“Redshift” gets its name from the way wavelengths of light lengthen. The farther away something is in the universe, the longer its wavelength of light. Scientists who study the cosmos call that lengthening the redshift effect.)

The concept of redshift works because the light we see from objects farther away from Earth is older than the light we see from objects closer to Earth — the light from distant objects has traveled a longer journey to reach us. That fact, together with a method to estimate temperature from light, allowed the researchers to measure the mean temperature of gases in the early universe — gases that surround objects farther away — and compare that mean with the mean temperature of gases closer to Earth — gases today.

Those gases in the universe today, the researchers found, reach temperatures of about 2 million degrees Kelvin — approximately 4 million degrees Fahrenheit, around objects closer to Earth. That is about 10 times the temperature of the gases around objects farther away and further back in time.

The universe, Chiang said, is warming because of the natural process of galaxy and structure formation. It is unrelated to the warming on Earth. “These phenomena are happening on very different scales,” he said. “They are not at all connected.”

References : Chiang, Yi-Kuan; Makiya, Ryu; Ménard, Brice; Komatsu, Eiichiro, “The Cosmic Thermal History Probed by Sunyaev-Zeldovich Effect Tomography”, The Astrophysical Journal, Volume 902, Issue 1, id.56, 17 doi:10.3847/1538-4357/abb403 https://ui.adsabs.harvard.edu/abs/2020ApJ.902.56C/abstract

Provided by Ohio state University

Food

Sweet Taste Reduces Appetite? (Food)

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The sweet taste of sugar is very popular worldwide. In Austria and Germany, the yearly intake per person adds up to about 33 and 34 kilograms, respectively. Thus, sugar plays an increasingly role in the nutrition and health of the population, especially with regard to body weight. However, little is known about the molecular (taste) mechanisms of sugar that influence dietary intake, independently of its caloric load.

Taste receptor and satiety regulation

“We therefore investigated the role of sweet taste receptor activation in the regulation of satiety,” says Veronika Somoza, deputy head of the Department of Physiological Chemistry at the University of Vienna and director of the Leibniz Institute for Food Systems Biology at the Technical University of Munich.

For this purpose, the scientists conducted a blinded, cross-over intervention study with glucose and sucrose. A total of 27 healthy, male persons, between 18 and 45 years of age, received either a 10 percent glucose or sucrose solution (weight percent) or one of the sugar solutions supplemented with 60 ppm lactisole. Lactisole is a substance that binds to a subunit of the sweet receptor and reduces the perception of sweet taste. Despite different types of sugar, all solutions with or without lactisole had the same energy content.

Two hours after drinking each of the test solutions, the participants were allowed to have as much as breakfast they wanted. Shortly before and during the 120-min waiting period, the researchers took blood samples in regular intervals and measured their body temperature.

Additional 100 kilocalories on average

After the consumption of the lactisole-containing sucrose solution, the test persons had an increased energy intake from breakfast of about 13 percent, about 100 kilocalories more, than after drinking the sucrose solution without lactisole. In addition, the subjects of this group showed lower body temperature and reduced plasma serotonin concentrations. Serotonin is a neurotransmitter and tissue hormone which, among other things, has an appetite-suppressing effect. In contrast, the researchers observed no differences after administration of the lactisole-containing glucose solution and the pure glucose solution.

“This result suggests that sucrose, regardless of its energy content, modulates the regulation of satiety and energy intake via the sweet taste receptor,” says Barbara Lieder, head of Christian Doppler Laboratory for Taste Research and also deputy head of the Department of Physiological Chemistry of the Faculty of Chemistry at University of Vienna.

The first study author of the study, Kerstin Schweiger, University of Vienna adds: “We do not know yet why we could not observe the lactisole effect with glucose. However, we suspect it is because glucose and sucrose activate the sweet receptor in different ways. We also assume that mechanisms independent of the sweet receptor play a role.”

“So there is still a lot of research needed to clarify the complex relationships between sugar consumption, taste receptors and satiety regulation on the molecular level,” says Veronika Somoza. In particular, as sweet receptors are also found in the digestive tract and little is known about their function there. The first steps have nevertheless been taken.

References : Sweet Taste Antagonist Lactisole Administered in Combination with Sucrose, But Not Glucose, Increases Energy Intake and Decreases Peripheral Serotonin in Male Subjects: Schweiger K et al., Nutrients 2020, 12(10), 3133; https://www.mdpi.com/2072-6643/12/10/3133

Provided by University of Vienna

PHYSICS

Surrey Helps To Produce The World’s First Neutron-rich, Radioactive Tantalum Ions (Physics)

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An international team of scientists have unveiled the world’s first production of a purified beam of neutron-rich, radioactive tantalum ions. This development could now allow for lab-based experiments on exploding stars helping scientists to answer long-held questions such as “where does gold come from?”

In a paper published in Physical Review Letters, the University of Surrey together with its partners detail how they used a new isotope-separation facility, called KISS, which is developed and operated by the Wako Nuclear Science Centre (WNSC) in the High Energy Accelerator Research Organization (KEK), Japan, to make beams of heavy tantalum isotopes.

The chemical element of tantalum is extremely difficult to vaporise, so the team had to capture radioactive tantalum atoms in high-pressure argon gas, ionising the atoms with precisely tuned lasers. A single isotope of radioactive tantalum could then be selected for detailed investigation.

In the study, the team found that when produced in a metastable state, tantalum-187’s nucleus fleetingly rotated in an irregular manner. The team discovered that tantalum-187’s gamma-ray “fingerprint” was characteristic of a prolate (American football) shape but simultaneously with a hint of an oblate (pancake) shape.

The team believe their results hint at the possibility of tantalum’s more dramatic shape-change to a full oblate rotation which they aim to explore in detail in future experiments.

Philip Walker, Emeritus Professor of Physics at the University of Surrey, said: “Theory suggests that just two more neutrons could tip the shape of tantalum-187 from prolate to oblate, so tantalum-189 is an objective for future investigation. However, it now seems to be a real possibility to go further and reach uncharted tantalum-199, with 126 neutrons, to test the exploding-star mechanism.”

Yoshikazu Hirayama, Associate Professor of WNSC in KEK, said: “Our KISS is a unique facility which can provide unexplored heavy nuclei, such as tantalum-187, 189, and 199, for the studies of exotic nuclear structures. We have started to delve into the mechanism of the synthesis of elements in the universe through the nuclear studies at KISS.”

References: P. M. Walker, Y. Hirayama, G. J. Lane, H. Watanabe, G. D. Dracoulis, M. Ahmed, M. Brunet, T. Hashimoto, S. Ishizawa, F. G. Kondev, Yu. A. Litvinov, H. Miyatake, J. Y. Moon, M. Mukai, T. Niwase, J. H. Park, Zs. Podolyák, M. Rosenbusch, P. Schury, M. Wada, X. Y. Watanabe, W. Y. Liang, and F. R. Xu, “Properties of 187Ta Revealed through Isomeric Decay”, Phys. Rev. Lett. 125, 192505 – Published 6 November 2020. https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.125.192505

Provided by University of Surrey

Biology

High Temperatures Threaten The Survival of Insects (Biology)

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Insects have difficulties handling the higher temperatures brought on by climate change, and might risk overheating. The ability to reproduce is also strongly affected by rising temperatures, even in northern areas of the world, according to a new study from Lund University in Sweden.

Insects cannot regulate their own body temperature, which is instead strongly influenced by the temperature in their immediate environment. In the current study, the researchers studied two closely related species of damselflies in Sweden. The goal was to understand their robustness and ability to tolerate changes in temperature.

To study this, the researchers used a combination of field work in southern Sweden and infrared camera technology (thermography), a technology that makes it possible to measure body temperature in natural conditions. This information was then connected to the survival rates and reproductive success of the damselflies in their natural populations.

The results show that survivorship of these damselflies was high at relatively low temperatures, 15 – 20 C °. The reproductive capacity, on the other hand, was higher at temperatures between 20 and 30 C °, depending on the species.

“There is therefore a temperature-dependent conflict between survival on one hand and the ability to reproduce on the other”, says Erik Svensson, professor at the Department of Biology at Lund University, who led the study.

The study also shows that the damselflies ability to handle heat-related stress is limited. Insects are cold-blooded invertebrates, so they rely on external sources such as the sun or hot stones to raise their body temperature.

“Our results show that cold-blooded animals can suffer from overheating even if they live far up in the northern hemisphere, and that their ability to buffer their body temperature against rising external temperatures is limited. The results also challenge a popular theory that animals’ plasticity, i. e. their individual flexibility, can help them survive under harsher environmental conditions, such as during heat waves”, says Erik Svensson.

Provided by Lund University

Planetary Science

SwRI Scientist Studies Tiny Craters On Bennu Boulders to Understand Asteroid’s Age (Planetary Science)

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Scientists inferred Bennu’s sojourn in the inner Solar System at 1.75 million years.

Last week NASA snagged a sample from the surface of asteroid Bennu, an Empire State Building-sized body that Southwest Research Institute scientists have helped map with nearly unprecedented precision. Using orbital data from the OSIRIS-REx spacecraft, researchers measured centimeter- to meter-sized craters on the boulders scattered around its rugged surface to shed light on the age of the asteroid.

SwRI and the University of Arizona studied centimeter- to meter-sized craters on boulders scattered around the surface of the near-Earth asteroid Bennu. This composite shows the cascading rim of an ancient crater from the time Bennu resided in the asteroid belt. The overlaid colors highlight the topography of the boulder with warmer colors indicating higher elevations. ©University of Arizona/Johns Hopkins APL/York University.

While the collected sample will yield enormous scientific value when it is returned to Earth in 2023, a key job for scientists during the time in orbit at Bennu was to understand the geology of the entire asteroid to provide important context for the sample. This provides insights into all the processes that might have affected the nature of the sample.

“The amazing data collected by OSIRIS-REx at asteroid Bennu have allowed us to not just find impact craters across its surface, but to actually find and study the craters on the surfaces of boulders,” said SwRI’s Dr. Kevin Walsh, a coauthor of “Bennu’s near-Earth lifetime of 1.75 million years inferred from craters on its boulders,” published October 26 in the journal Nature. “The craters that we could observe and measure on the surfaces of boulders allowed us to estimate their strengths, a first-of-its-kind measurement.”

Bennu is a dark rubble pile held together by gravity and thought to be an asteroid remnant created following a collision involving a larger main-belt object. Boulders are scattered across its heavily cratered surface, indicating that it has had a rough-and-tumble life since being liberated from its much larger parent asteroid millions or even billions of years ago. Scientists use studies of impact craters to determine the ages of planetary surfaces.

Team members from the University of Arizona developed a mathematical formula that allows researchers to calculate the maximum impact energy a boulder of a given size and strength could endure before being smashed.

Walsh, lead author Dr. Ron Ballouz (a postdoctoral fellow at the University of Arizona), and colleagues brought together an understanding of the number of craters, the strength of the materials impacted, and the numbers of impactors to help constrain the chronology of Bennu’s existence in the inner Solar System at 1.75 million years. Since the spacecraft arrived at Bennu in 2018, scientists have been characterizing the asteroid’s composition from orbit and comparing it to other asteroids and meteorites. Now NASA has collected an actual sample of its surface that scientists will be able to study.

“We held our breath as the spacecraft touched the asteroid’s boulder-strewn surface with a robotic arm for a few seconds to collect a sample of rocks and dust on October 20 — a first for NASA,” Walsh said. “Hitting pay dirt on the first attempt is fantastic. We look forward to learning so much more when the sample arrives back at Earth in 2023.”

The manuscript describes a method for measuring the strength of solid objects uses remote observations of craters on surface boulders. Determining the strengths of boulders on asteroid surfaces is a leap forward from measuring the strength of much smaller meteorites, which have the bias of surviving passage through Earth’s atmosphere.

“The rocks tell their history through the craters they accumulated over time,” said Ballouz. “The boulders serve as witnesses to Bennu’s time as a near-Earth asteroid, validating decades of dynamical studies of the lifetime of near-Earth asteroids.”

Provided by Southwest Research Institute

Amazing places

Scientists have discovered an ancient lake bed deep beneath the Greenland ice (Amazing Places)

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Scientists have detected what they say are the sediments of a huge ancient lake bed sealed more than a mile under the ice of northwest Greenland–the first-ever discovery of such a sub-glacial feature anywhere in the world. Apparently formed at a time when the area was ice-free but now completely frozen in, the lake bed may be hundreds of thousands or millions of years old, and contain unique fossil and chemical traces of past climates and life. Scientists consider such data vital to understanding what the Greenland ice sheet may do in coming years as climate warms, and thus the site makes a tantalizing target for drilling. A paper describing the discovery is in press at the journal Earth and Planetary Science Letters.

The largely featureless surface of the Greenland ice sheet, as seen from the window of a P3 aircraft carrying geophysical instruments aimed at detecting geologic features underneath. ©Kirsty Tinto/Lamont-Doherty Earth Observatory.

“This could be an important repository of information, in a landscape that right now is totally concealed and inaccessible,” said Guy Paxman, a postdoctoral researcher at Columbia University’s Lamont-Doherty Earth Observatory and lead author of the report. “We’re working to try and understand how the Greenland ice sheet has behaved in the past. It’s important if we want to understand how it will behave in future decades.” The ice sheet, which has been melting at an accelerating pace in recent years, contains enough water to raise global sea levels by about 24 feet.

The researchers mapped out the lake bed by analyzing data from airborne geophysical instruments that can read signals that penetrate the ice and provide images of the geologic structures below. Most of the data came from aircraft flying at low altitude over the ice sheet as part of NASA’s Operation IceBridge.

The team says the basin once hosted a lake covering about 7,100 square kilometers (2,700 square miles), about the size of the U.S. states of Delaware and Rhode Island combined. Sediments in the basin, shaped vaguely like a meat cleaver, appear to range as much as 1.2 kilometers (three quarters of a mile) thick. The geophysical images show a network of at least 18 apparent onetime stream beds carved into the adjoining bedrock in a sloping escarpment to the north that must have fed the lake. The image also show at least one apparent outlet stream to the south. The researchers calculate that the water depth in the onetime lake ranged from about 50 meters to 250 meters (a maximum of about 800 feet).

A newly forming lake at the edge of the Greenland ice sheet, exposing sediments released by the ice. Such lake beds are becoming common as the ice recedes. ©Kevin Krajick/Earth Institute

In recent years, scientists have found existing subglacial lakes in both Greenland and Antarctica, containing liquid water sandwiched in the ice, or between bedrock and ice. This is the first time anyone has spotted a fossil lake bed, apparently formed when there was no ice, and then later covered over and frozen in place. There is no evidence that the Greenland basin contains liquid water today.

Paxman says there is no way to tell how old the lake bed is. Researchers say it is likely that ice has periodically advanced and retreated over much of Greenland for the last 10 million years, and maybe going back as far as 30 million years. A 2016 study led by Lamont-Doherty geochemist Joerg Schaefer has suggested that most of the Greenland ice may have melted for one or more extended periods some time in the last million years or so, but the details of that are sketchy. This particular area could have been repeatedly covered and uncovered, Paxman said, leaving a wide range of possibilities for the lake’s history. In any case, Paxman says, the substantial depth of the sediments in the basin suggest that they must have built up during ice-free times over hundreds of thousands or millions of years.

“If we could get at those sediments, they could tell us when the ice was present or absent,” he said.

The researchers assembled a detailed picture of the lake basin and its surroundings by analyzing radar, gravity and magnetic data gathered by NASA. Ice-penetrating radar provided a basic topographic map of the earth’ s surface underlying the ice. This revealed the outlines of the smooth, low-lying basin, nestled among higher-elevation rocks. Gravity measurements showed that the material in the basin is less dense than the surrounding hard, metamorphic rocks–evidence that it is composed of sediments washed in from the sides. Measurements of magnetism (sediments are less magnetic than solid rock) helped the team map the depths of the sediments.

Using geophysical instruments, scientists have mapped a huge ancient lake basin (outlined here in red) below the Greenland ice, covering about 2,700 square miles). Redder colors signify higher elevations, green ones lower. A stream system incised into the bedrock that once fed the lake is shown in blue. ©Adapted from Paxman et al., EPSL, 2020

The researchers say the basin may have formed along a now long-dormant fault line, when the bedrock stretched out and formed a low spot. Alternatively, but less likely, previous glaciations may have carved out the depression, leaving it to fill with water when the ice receded.

What the sediments might contain is a mystery. Material washed out from the edges of the ice sheet have been found to contain the remains of pollen and other materials, suggesting that Greenland may have undergone warm periods during the last million years, allowing plants and maybe even forests to take hold. But the evidence is not conclusive, in part because it is hard to date such loose materials. The newly discovered lake bed, in contrast, could provide an intact archive of fossils and chemical signals dating to a so-far unknown distant past.

The basin “may therefore be an important site for future sub-ice drilling and the recovery of sediment records that may yield valuable insights into the glacial, climatological and environmental history” of the region, the researchers write. With the top of the sediments lying 1.8 kilometers below the current ice surface (1.1 miles), such drilling would be daunting, but not impossible. In the 1990s, researchers penetrated almost 2 miles into the summit of the Greenland ice sheet and recovered several feet of bedrock–at the time, the deepest ice core ever drilled. The feat, which took five years, has not since been repeated in Greenland, but a new project aimed at reaching shallower bedrock in another part of northwest Greenland is being planned for the next few years.

Provided by Earth Institute at Columbia Umiversity