Making Clean Hydrogen Is Hard, But Researchers Just Solved a Major Hurdle (Chemistry)

For decades, researchers around the world have searched for ways to use solar power to generate the key reaction for producing hydrogen as a clean energy source — splitting water molecules to form hydrogen and oxygen. However, such efforts have mostly failed because doing it well was too costly, and trying to do it at a low cost led to poor performance.

Now, researchers from The University of Texas at Austin have found a low-cost way to solve one half of the equation, using sunlight to efficiently split off oxygen molecules from water. The finding, published recently in Nature Communications, represents a step forward toward greater adoption of hydrogen as a key part of our energy infrastructure.

As early as the 1970s, researchers were investigating the possibility of using solar energy to generate hydrogen. But the inability to find materials with the combination of properties needed for a device that can perform the key chemical reactions efficiently has kept it from becoming a mainstream method.

“You need materials that are good at absorbing sunlight and, at the same time, don’t degrade while the water-splitting reactions take place,” said Edward Yu, a professor in the Cockrell School’s Department of Electrical and Computer Engineering. “It turns out materials that are good at absorbing sunlight tend to be unstable under the conditions required for the water-splitting reaction, while the materials that are stable tend to be poor absorbers of sunlight. These conflicting requirements drive you toward a seemingly inevitable tradeoff, but by combining multiple materials — one that efficiently absorbs sunlight, such as silicon, and another that provides good stability, such as silicon dioxide — into a single device, this conflict can be resolved.”

However, this creates another challenge — the electrons and holes created by absorption of sunlight in silicon must be able to move easily across the silicon dioxide layer. This usually requires the silicon dioxide layer to be no more than a few nanometers, which reduces its effectiveness in protecting the silicon absorber from degradation.

The key to this breakthrough came through a method of creating electrically conductive paths through a thick silicon dioxide layer that can be performed at low cost and scaled to high manufacturing volumes. To get there, Yu and his team used a technique first deployed in the manufacturing of semiconductor electronic chips. By coating the silicon dioxide layer with a thin film of aluminum and then heating the entire structure, arrays of nanoscale “spikes” of aluminum that completely bridge the silicon dioxide layer are formed. These can then easily be replaced by nickel or other materials that help catalyze the water-splitting reactions.

When illuminated by sunlight, the devices can efficiently oxidize water to form oxygen molecules while also generating hydrogen at a separate electrode and exhibit outstanding stability under extended operation. Because the techniques employed to create these devices are commonly used in manufacturing of semiconductor electronics, they should be easy to scale for mass production.

The team has filed a provisional patent application to commercialize the technology.

Improving the way hydrogen is generated is key to its emergence as a viable fuel source. Most hydrogen production today occurs through heating steam and methane, but that relies heavily on fossil fuels and produces carbon emissions.

There is a push toward “green hydrogen” which uses more environmentally friendly methods to generate hydrogen. And simplifying the water-splitting reaction is a key part of that effort.

Water splitting graphic
Graphic shows the basic geometry and functionality of the photoanode device. © Cockrell School of Engineering, The University of Texas at Austin

Hydrogen has potential to become an important renewable resource with some unique qualities. It already has a major role in significant industrial processes, and it is starting to show up in the automotive industry. Fuel cell batteries look promising in long-haul trucking, and hydrogen technology could be a boon to energy storage, with the ability to store excess wind and solar energy produced when conditions are ripe for them.

Going forward, the team will work to improve the efficiency of the oxygen portion of water-splitting by increasing the reaction rate. The researchers’ next major challenge is then to move on to the other half of the equation.

“We were able to address the oxygen side of the reaction first, which is the more challenging part, ” Yu said, “but you need to perform both the hydrogen and oxygen evolution reactions to completely split the water molecules, so that’s why our next step is to look at applying these ideas to make devices for the hydrogen portion of the reaction.”

This research was funded by the U.S. National Science Foundation through the Directorate for Engineering and the Materials Research Science and Engineering Centers (MRSEC) program. Yu worked on the project with UT Austin students Soonil Lee and Alex De Palma, along with Li Ji, a professor at Fudan University in China.

Featured image: The team’s experimental water-splitting apparatus. © Cockrell School of Engineering, The University of Texas at Austin


Reference: Lee, S., Ji, L., De Palma, A.C. et al. Scalable, highly stable Si-based metal-insulator-semiconductor photoanodes for water oxidation fabricated using thin-film reactions and electrodeposition. Nat Commun 12, 3982 (2021). https://doi.org/10.1038/s41467-021-24229-y


Provided by Cockrell School of Engineering

RNA Modification May Protect Against Liver Disease (Medicine)

May also explain liver fat differences among men & women

FINDINGS

A chemical modification that occurs in some RNA molecules as they carry genetic instructions from DNA to cells’ protein-making machinery may offer protection against non-alcoholic fatty liver, a condition that results from a build-up of fat in the liver and can lead to advanced liver disease, according to a new study by UCLA researchers.

The study, conducted in mice, also suggests that this modification — known as m6A, in which a methyl group attaches to an RNA chain — may occur at a different rate in females than it does in males, potentially explaining why females tend to have higher fat content in the liver. The researchers found that without the m6A modification, differences in liver fat content between the sexes were reduced dramatically.

In addition, in a preclinical model, the investigators demonstrated that gene therapy can be used to enhance or add modifications to key RNAs to slow down or reduce the severity of liver disease.

BACKGROUND

Fatty liver can develop when liver fat content increases due to dietary or genetic factors, potentially leading to advanced liver scarring and disease, as seen in cirrhosis and other conditions. High liver fat content is also associated with increased risk of cardiovascular disease.

In recent years, scientists have identified hundreds of chemical modifications like m6A that can occur in RNA molecules, altering the RNA’s instructions for making proteins without affecting the core DNA. Some modifications can be beneficial, as in the case of liver disease; others can have a detrimental effect.

METHOD

Using a unique mouse model missing m6A RNA modifications in the liver and a control model that included the modifications, the authors compared the effects of diets with differing fat contents to assess the effects of the modifications on fatty liver disease. In addition, they used measurements from human patients who had undergone liver biopsies during bariatric surgery to correlate markers of m6A RNA modifications with liver fat content and inflammation.

IMPACT

A key question moving forward is how genetic and environmental factors affect the body’s natural ability to create RNA modifications. Because m6A appears to act as a protective checkpoint that slows the accumulation of fat in the liver, the investigators hope their findings will spur future research on the development of therapies to enhance chemical modifications as a way to protect against liver disease and similar disorders.

###

AUTHORS

The study was led by Dr. Tamer Sallam, an associate professor of medicine at the David Geffen School of Medicine at UCLA. Other authors included David Salisbury, Zhengyi Zhang, Dan Wang, Jason Kim, Xiaohui Wu, Laurent Vergnes, Kevin Williams, Adriana Huertas-Vazquez and Karen Reue, all of UCLA; David Casero of Cedars-Sinai; Aashiq Mirza and Dr. Samie Jaffrey of Cornell University; Paola Leon-Mimila of the National Autonomous University of Mexico (UNAM); and Jianjun Chen of the City of Hope Medical Institute.

JOURNAL

The study is published today in the journal Nature Metabolism.

FUNDING

Funding for the study was provided by grants from the National Institutes of Health, an American Heart Association Transformational Project grant and a Burroughs Wellcome Fund Career Award for Medical Scientists.

Featured image: Schematic representation of m6A modifications (blue) attaching to RNA in the liver © Sallam Lab/UCLA


Reference: Salisbury, D.A., Casero, D., Zhang, Z. et al. Transcriptional regulation of N6-methyladenosine orchestrates sex-dimorphic metabolic traits. Nat Metab (2021). https://doi.org/10.1038/s42255-021-00427-2


Provided by UCLA Health

New Material Could Mean Lightweight Armor, Protective Coatings (Material Science)

Army-funded research identified a new material that may lead to lightweight armor, protective coatings, blast shields and other impact-resistant structures.

Researchers at the U.S. Army’s Institute for Soldier Nanotechnologies at the Massachusetts Institute of TechnologyCaltech and ETH Zürich found that materials formed from precisely patterned nanoscale trusses are tougher than Kevlar and steel.

In experiments, the ultralight structures, called nanoarchitectured materials, absorbed the impact of microscopic projectiles accelerated to supersonic speeds.

“Increasing protection while simultaneously decreasing the weight that soldiers carry is an overreaching theme in our research,” said Dr. James Burgess, ISN program manager for the U.S. Army Combat Capabilities Development Command, known as DEVCOM, Army Research Laboratory. “This project is a really good example of such efforts where projectile energy absorption is nanostructured mechanism based.”

The research, published in Nature Materials, found that the material prevented the projectiles from tearing through it.

“The same amount of mass of our material would be much more efficient at stopping a projectile than the same amount of mass of Kevlar,” said Dr. Carlos Portela, assistant professor of mechanical engineering at MIT, the study’s lead author.

The researchers calculate that the new material absorbs impacts more efficiently than steel, Kevlar, aluminum and other impact-resistant materials of comparable weight.

“The knowledge from this work…could provide design principles for ultra-lightweight impact resistant materials [for use in] efficient armor materials, protective coatings, and blast-resistant shields desirable in defense and space applications,” said co-author Dr. Julia R. Greer, a professor of materials science, mechanics, and medical engineering at Caltech, whose lab fabricated the material.

Nanoarchitected materials are known to feature impressive properties like exceptional lightness and resilience; however, until now, the potential for additional applications has largely been untested.

“We only know about its response in a slow-deformation regime, whereas a lot of their practical use is hypothesized to be in real-world applications where nothing deforms slowly,” Portela said.

To help fill this vital knowledge gap, the research team set out to study nanoarchitected materials undergoing fast deformation, such as that caused by high-velocity impacts. At Caltech, researchers first fabricated a repeating pattern known as a tetrakaidecahedron—a lattice configuration composed of microscopic struts—using two-photo lithography, a technique that uses a high-powered laser to solidify microscopic structures in photosensitive resin.

To test the tetrakaidecahedron’s resilience to extreme, rapid deformation, the team performed experiments at MIT using the ISN-developed laser-induced particle impact array. This device aims an ultrafast laser through a glass slide.. As the laser passes through the slide, it generates a plasma, an immediate expansion of gas that launches the particles toward the target.

By adjusting the laser’s power to control the speed of the microparticle projectiles, the researchers tested microparticle velocities within the supersonic range.

“Some experiments achieved twice the speed of sound, easily,” Portela said.

Using a high-speed camera, the researchers captured videos of the microparticles impacting the nanoarchitected material. They had fabricated material of two different densities. A comparison of the two materials’ impact response, found the denser one to be more resilient, and microparticles tended to embed in the material rather than tear through it.

To get a closer look, the researchers carefully sliced through the embedded microparticles and nanarchitectured target. They found that the struts below the embedded particle had crumpled and compacted in response to the impact, but the surrounding struts remained intact.

“We show the material can absorb a lot of energy because of this shock compaction mechanism of struts at the nanoscale, versus something that’s fully dense and monolithic, not nanoarchitected,” Portela said.

Going forward, Portela plans to explore various nanostructured configurations other than carbon, and ways to scale up the production of these nanostructures, all with the goal of designing tougher, lighter materials.

“Nanoarchitected materials truly are promising as impact-mitigating materials,” Portela said. “There’s a lot we don’t know about them yet, and we’re starting this path to answering these questions and opening the door to their widespread applications.”

The U.S. Army established the MIT Institute for Nanotechnologies in 2002 as an interdisciplinary research center to dramatically improve the protection, survivability and mission capabilities of the Soldier and of Soldier-supporting platforms and systems.

In addition to Army funding through the institute, the U.S. Office of Naval Research and the Vannevar Bush Faculty Fellowship supported the research.


Provided by US Army

Chemists Found An Effective Remedy For “Aged” Brain Diseases (Neuroscience)

Scientists obtained substances that provide a breakthrough in the treatment of neurodegenerative pathologies

Russian scientists have synthesized chemical compounds that can stop the degeneration of neurons in Alzheimer’s, Parkinson’s, and other severe brain pathologies. These substances can provide a breakthrough in the treatment of neurodegenerative pathologies. New molecules of pyrrolyl- and indolylazine classes activate intracellular mechanisms to combat one of the main causes of “aged” brain diseases – an excess of so-called amyloid structures that accumulate in the human brain with age. The essence of the study was published in the European Journal of Medicinal Chemistry. Experts from the Institute of Cytology of the Russian Academy of Sciences, the Institute of Organic Synthesis of the Ural Branch of the Russian Academy of Sciences, and the Ural Federal University (UrFU) took part in the study.

“Our compounds activate the synthesis of specific heat shock proteins and cause their accumulation in the cell,” said research co-author, professor of the Department of Organic and Biomolecular Chemistry at UrFU Irina Utepova. “Proteins of this type make it possible to protect neuronal tissue from an excess of toxic amyloids and to protect cells from various types of stress, including proteotoxic stress characteristic of neurodegenerative diseases.”

Important advantages of compounds from the series of pyrrolyl- and indolylazine classes are a profitable synthesis technology and low toxicity.

The obtained compounds were tested in cellular models of Alzheimer’s disease and secondary injuries after traumatic brain injury. In both cases, the new substances demonstrated a significant therapeutic effect, increasing the survival of neuronal cells. The most effective compound has been tested in living tissues of rats with secondary injuries after traumatic brain injury.

According to scientists, the use of pyrrolylazine in rehabilitation therapy allowed the animals to avoid the appearance of movement disorders and degeneration of hippocampal neurons. The research team has been continued to study the mechanism of action of new compounds and is preparing for their preclinical testing.

Featured image: Russian chemists obtained new molecules of the indolyl- and pyrrolylazine series © UrFU / Anastasia Kurshpel


Reference: Elizaveta A. Dutysheva, Irina A. Utepova, Maria A. Trestsova, Alexander S. Anisimov, Valery N. Charushin, Oleg N. Chupakhin, Boris A. Margulis, Irina V. Guzhova, Vladimir F. Lazarev, Synthesis and approbation of new neuroprotective chemicals of pyrrolyl- and indolylazine classes in a cell model of Alzheimer’s disease, European Journal of Medicinal Chemistry, Volume 222, 2021, 113577, ISSN 0223-5234, https://doi.org/10.1016/j.ejmech.2021.113577. (https://www.sciencedirect.com/science/article/pii/S0223523421004268)


Provided by URFU

USC Study Shows Male-female Differences in Immune Cell Function (Biology)

A new USC study of a common, yet poorly understood type of white blood cell reveals the immune cell’s response to pathogens differs greatly by sex and by age.

In this mouse study, males proved much more susceptible to a condition called sepsis than females. However, the scientists also found that the female disease-defense system is hardly perfect; their system changes with age to become nearly as harmful as the males’.

Those are the key findings in a study that appears today in Nature Aging.

The study has important implications for studying disease and cures, especially for sepsis, a condition in which the body’s defense system turns harmful to itself. It also suggests that the quest for precision medicine may be overlooking more obvious disease determinants: age and sex.

“A big take-home message is that with the push for personalized medicine, people focus on minute genetic differences, but we find that biological sex – the biggest genetic difference of all – is actually a great predictor for immune response seldom taken into account,” said Bérénice Benayoun, assistant professor at the USC Leonard Davis School of Gerontology and principal investigator of the study.

Benayoun and her team focused on cells called “neutrophils,” which make up about 50% to 70% of our white blood cells and are critical to fighting off infections. Understanding sex- and age-based differences in how neutrophils function could help us understand similar disparities in human illnesses, such as why older people — and men in particular– are more likely to get severe symptoms with COVID-19 or why women are more likely to have autoimmune disorders, she added.

Different defensive tactics

Neutrophils respond to infections in a few different ways, such as by engulfing and digesting an invading pathogen–or by degranulation in which they secrete proteins that destroy the invader.

Another method discovered in 2004 is “NETosis,” in which neutrophils expel strands of their own coagulated DNA, called chromatin, which act as a trap outside of the cell. These neutrophil extracellular traps, or so-called “NETs,” ensnare and destroy pathogens.

Benayoun and colleagues discovered differences in neutrophil activity between young and old mice, as well as between male and female mice. Males appeared to have more degranulation activity, as evidenced by higher levels of a protein, neutrophil elastase. Meanwhile females exhibited more NETosis on average.

High degranulation activity can cause damage to surrounding tissues, and these findings could illustrate why sepsis affects men more than women, Benayoun said.

“With sepsis, what kills you is not actually the bacteria; it’s your response to the bacteria,” she noted. “And we know that males in general have much worse odds during sepsis than females, and neutrophil elastase, which is one of the main components of degranulation, is one of the big things that can be produced at very high level during sepsis.”

On the other hand, higher NETosis activity could contribute to the body’s immune system attacking healthy cells, Benayoun added. Antibodies targeting the body’s own DNA have been found in many autoimmune disorders, which could have been developed after neutrophils produced too many NETs. Thus, higher NET activity in females could be related to higher rates of autoimmune disorders in women.

“If you make NETs for no good reason, it can promote autoimmunity,” Benayoun said. “It’s a known fact that women are more prone to autoimmune disease, like a 9:1 ratio compared to men.”

With age, female neutrophils became more reactive, in contrast to male neutrophils. “In general, genetic programs seem to ‘age’ at a faster rate in male neutrophils,” she said. “These findings suggest that sex differences can become amplified with aging, at least for neutrophils.”

A new resource for immune system study

Neutrophils have historically been difficult to study because they are so short-lived, lasting less than a day. The cells’ short lifespans are spent as the immune system’s first responders, working quickly to trap and destroy pathogens at the first sign of an infection and sacrificing themselves in the process.

Applying machine learning techniques to the data, the team has begun to identify genetic pathways involved in the regulation of immune response that could explain why there are such dramatic differences between the sexes, also called sex dimorphism, in immune system activity.

Sex dimorphism in immunity has played out in the current pandemic: Most of the severe COVID-19 cases and deaths were men, Benayoun noted. With other literature indicating a possible role of sex hormones in immunity, studying these interactions could lead scientists to discover new techniques to fight severe illness.

“If these differences are driven by the hormonal effects on immune cells, then in theory, you could try to intervene in early sepsis, maybe with anti-androgens in the short term, to bring down the response,” Benayoun mused. “You could tailor medicine just by using the fact that this patient has more androgens or this person has more estrogen.”

In addition to Benayoun, study co-authors include Ryan J. Lu, Minhoo Kim and Juan Bravo of the USC Leonard Davis School; Shalina Taylor, Kévin Contrepois, and Mathew Ellenberger of Stanford University; and Nirmal K. Sampathkumar of King’s College London, U.K.

The work was supported by a Diana Jacobs Kalman/AFAR Scholarships for Research in the Biology of Aging to Lu; GCRLE-2020 post-doctoral fellowship from the Global Consortium for Reproductive Longevity and Equality at the Buck Institute, made possible by the Bia-Echo Foundation, to Kim; NIA T32 AG052374 and NSF graduate research fellowship DGE-1842487 to Bravo; and NIA R00 AG049934, Pew Biomedical Scholar award #00034120, an innovator grant from the Rose Hills Foundation, and the Kathleen Gilmore Biology of Aging research award to Benayoun. This work was also partially supported by NCI Cancer Center Support Grant P30 CA014089 through the use of shared resources.

Featured image: A neutrophil undergoes NETosis, expelling chromatin to ensnare and destroy a pathogen. © Ryan Lu


Reference: Lu, R.J., Taylor, S., Contrepois, K. et al. Multi-omic profiling of primary mouse neutrophils predicts a pattern of sex- and age-related functional regulation. Nat Aging (2021). https://doi.org/10.1038/s43587-021-00086-8


Provided by USC

Researchers Discover How Cancer Cells That Spread To Lymph Nodes Avoid Immune Destruction (Medicine)

Blood pressure drug losartan may help thwart this evasion tactic.

Lymph nodes are critical to the body’s immune response against tumors but paradoxically, cancer cells that spread, or metastasize, to lymph nodes can often avoid being eliminated by immune cells. Recent experiments by investigators at Massachusetts General Hospital (MGH) and Boston University School of Medicine provide insights on the details behind this immune evasion, which could help scientists develop strategies to overcome it. The findings are published in Nature Biomedical Engineering.

“We know that lymph nodes are often the first place cancer spreads as it progresses. We also know that our immune system can attack and kill cancer cells,” explains senior and co-corresponding author Timothy P. Padera, PhD, an investigator in Radiation Oncology at MGH and a 2021-2026 MGH Research Scholar. “One of the perplexing questions that has been at the core of the recent work in my lab is how can organs that generate our immune responses–lymph nodes–permit cancer cells to survive and take them over instead of attacking them? This was the driving motivation behind this study.”

By analyzing patient tissue from breast, colon, and head and neck cancers, combined with animal models of breast cancer lymph node metastases, Padera and his colleagues showed that immune cells called T cells are abundant in metastatic lymph nodes but fail to penetrate tumors that have spread to such nodes. The team measured increased physical forces, known as solid stress, in lymph nodes with metastatic cancer. “We hypothesized that solid stress in lymph node tumors can impair both blood flow and the T cell trafficking capacity of blood vessels in lymph nodes,” says lead and co-corresponding author Dennis Jones, PhD, an assistant professor of Pathology & Laboratory Medicine at the Boston University School of Medicine.

The scientists then developed a device to compress lymph nodes in order to simulate the gradual growth of lymph node metastases. When they applied compressive force to lymph nodes, there was a clear link between physical force and disruption of T cell entry into lymph nodes. “Our findings indicate that as cancer cells grow in the lymph node, they reorganize and alter the lymph node, disabling critical functional responses of the immune system,” says Padera. “By understanding how cancer cells are disabling lymph node function, we hope to fight back to help the lymph nodes generate anti-cancer immune responses, which will help fight cancer cells everywhere in the body.”

Alleviating solid stress with the blood pressure drug losartan boosted the numbers of blood vessels and T cells in lymph node metastases, suggesting that alleviating solid stress is a potential strategy to improve T cell entry into tumors.

“Our work now leads to many important additional questions,” says Jones. “Does losartan treatment combined with immunotherapy cause the eradication of metastatic cancer cells in lymph nodes by T cell killing? And further, does this lead to a strong systemic anti-cancer immune response that helps clear the cancer from the entire body?” Jones notes that finding the answers to these questions could lead to new treatment strategies for patients with metastatic cancer.

Padera is an associate professor of Radiation Oncology at Harvard Medical School. In addition to Jones and Padera, co-authors include Zixiong Wang, Ivy X. Chen, Sue Zhang, Rohin Banerji, Pin-Ji Lei, Hengbo Zhou, Victoria Xiao, Cecilia Kwong, Jan Willem M. van Wijnbergen, Ethel R. Pereira, Benjamin J. Vakoc, Peigen Huang, and Hadi T. Nia.

This study was supported by the National Institutes of Health, the Massachusetts General Hospital Executive Committee on Research, the Mass General Research Institute Research Scholars Program, and the METAvivor organization.


Reference: Jones, D., Wang, Z., Chen, I.X. et al. Solid stress impairs lymphocyte infiltration into lymph-node metastases. Nat Biomed Eng (2021). https://doi.org/10.1038/s41551-021-00766-1


Provided by Massachusetts General Hospital

Abelacimab Effective Blood Clot Treatment, McMaster-led Study Shows (Medicine)

A potentially game-changing treatment for people with, or at risk of, blood clots has been found effective by an international team of researchers led by McMaster University’s Jeffrey Weitz.

Weitz’s team compared abelacimab with enoxaparin as a control drug in 412 patients undergoing knee replacement surgery. Results showed that just one abelacimab injection prevents blood clots for up to a month after surgery, reducing the risk by about 80% compared with enoxaparin without increasing the risk of bleeding.

Their findings were published in the New England Journal of Medicine today, coinciding with Weitz’s presentation of the research at the International Society on Thrombosis and Hemostasis 2021 Congress.

Weitz, a hematologist, is a professor of medicine and of biochemistry and biomedical sciences at McMaster’s Michael G. DeGroote School of Medicine and executive director of the Thrombosis and Atherosclerosis Research Institute.

“Patients who undergo knee replacement routinely receive anti-clotting treatment with enoxaparin or other anticoagulant medications that require daily administration,” he said.

“With a single injection of abelacimab after surgery, we found much better protection against clots in the veins in the leg compared with enoxaparin, one of the current standards of care.”

Patients enrolled in the study were closely monitored for symptoms or signs of clotting or bleeding and underwent an x-ray of the veins of the operated leg to detect any possible clot formation.

Abelacimab’s potential to treat other cardiovascular conditions has Weitz and his fellow scientists excited.

“This success of abelacimab in this study provides the foundation for its use for prevention of stroke in patients with atrial fibrillation and for treatment of deep-vein thrombosis and pulmonary embolism, clots in the veins of the leg and clots in the lung, in patients with cancer,” said Weitz.

Abelacimab is an antibody that binds to both the inactive and activated forms of factor XI, one of the clotting factors, and prevents its activation and activity, thereby halting clot formation.

The study proved that factor XI is a key driver of clot formation after surgery, Weitz said, adding that the fact that abelacimab was more effective than enoxaparin, which inhibits clotting factors downstream to factor XI, highlights the importance of factor XI in clot formation.

“We expect factor XI to be a safer target for new anticoagulants than the targets of currently available anticoagulants because patients with congenital factor XI deficiency are at reduced risk for clots but rarely have spontaneous bleeding,” he said.

Weitz said new anti-clotting medications are often tested first on patients undergoing orthopedic surgery, such as knee replacement, because such patients are at risk for clots in the veins of their operated leg. Therefore, different doses of the drug can be evaluated to identify those that are both effective and safe compared with the standard of care such as enoxaparin.

These doses can then be carried forward into studies of patients with clots or at risk of clots, such as cancer associated clots or stroke prevention in patients with atrial fibrillation.

The study was funded by Anthos Therapeutics, based in Cambridge, Massachusetts, which is developing abelacimab.

Featured image: Dr. Jeffrey Weitz, professor of medicine, Michael G. DeGroote School of Medicine, McMaster University © McMaster University


Provided by McMaster University

Tail Without A Comet: The Dusty Remains Of Comet ATLAS (Planetary Science)

A serendipitous flythrough of the tail of a disintegrated comet has offered scientists a unique opportunity to study these remarkable structures, in new research presented today at the National Astronomy Meeting 2021.

Comet ATLAS fragmented just before its closest approach to the Sun last year, leaving its former tail trailing through space in the form of wispy clouds of dust and charged particles. The disintegration was observed by the Hubble Space Telescope in April 2020, but more recently the ESA spacecraft Solar Orbiter has flown close to the tail remnants in the course of its ongoing mission.

This lucky encounter has presented researchers with a unique opportunity to investigate the structure of an isolated cometary tail. Using combined measurements from all of Solar Orbiter’s in-situ instruments, the scientists have reconstructed the encounter with ATLAS’s tail. The resulting model indicates that the ambient interplanetary magnetic field carried by the solar wind ‘drapes’ around the comet, and surrounds a central tail region with a weaker magnetic field.

Comets are typically characterized by two separate tails; one is the well-known bright and curved dust tail, the other – typically fainter – is the ion tail. The ion tail originates from the interaction between the cometary gas and the surrounding solar wind, the hot gas of charged particles that constantly blows from the Sun and permeates the whole Solar System.

When the solar wind interacts with a solid obstacle, like a comet, its magnetic field is thought to bend and ‘drape’ around it. The simultaneous presence of magnetic field draping and cometary ions released by the melting of the icy nucleus then produces the characteristic second ion tail, which can extend for large distances downstream from the comet’s nucleus.

Lorenzo Matteini, a solar physicist at Imperial College London and leader of the work, says: “This is quite a unique event, and an exciting opportunity for us to study the makeup and structure of comet tails in unprecedented detail. Hopefully with the Parker Solar Probe and Solar Orbiter now orbiting the Sun closer than ever before, these events may become much more common in future!”

This is the first comet tail detection occurring so close to the Sun – well inside the orbit of Venus. It is also one of the very few cases where scientists have been able to make direct measurements from a fragmented comet. Data from this encounter is expected to contribute greatly to our understanding of the interaction of comets with the solar wind and the structure and formation of their ion tails. 

Featured image: Hubble Space Telescope image of comet C/2019 Y4 (ATLAS), taken on April 20 2020, providing the sharpest view to date of the breakup of the solid nucleus of the comet. Hubble’s eagle-eye view identifies as many as 30 separate fragments, and distinguishes pieces that are roughly the size of a house. Before the breakup, the entire nucleus of the comet may have been the length of one or two football fields. The comet was approximately 91 million miles (146 million kilometres) from Earth when the image was taken. Credit: NASA / ESA / STScI / D. Jewitt (UCLA)


Provided by RAS

EHT Pinpoints Dark Heart Of the Nearest Radio Galaxy (Cosmology)

The Event Horizon Telescope takes a close-up of the nearest radio galaxy

Centaurus is one of the most famous constellations in the southern sky. Within this constellation is the radio galaxy Centaurus A, which can be seen as a faint nebula using only binoculars. Like most galaxies, Centaurus A is also home to a supermassive black hole. With the Event Horizon Telescope (EHT), researchers have now zoomed into the heart of this galaxy some 13 million light years away. In the process, the team not only precisely determined the position of the black hole but also observed a gigantic jet originating there. This bundled gas stream appears to emit radiation only at its outer edges, thereby calling theoretical models into question.

Centaurus A shines in the radio range as a massive and bright object on the earthly firmament. In 1949, the galaxy with the catalogue number NGC 5128 was identified as one of the first extragalactic radio sources. Since then, astronomers have explored them extensively across the electromagnetic spectrum – not only in optical light and radio waves but also with infra-red, X-ray, and gamma-ray telescopes.

Centaurus A hides a black hole with a mass 55 million times that of the sun. In comparison, the gravity trap in the centre of the galaxy has a good four million solar masses, and the black hole in the giant elliptical galaxy M 87 has about six and a half billion. The latter was examined by the EHT in April 2017; the image of the shadow of this black hole, published two years later, has made a huge contribution to scientific history.

In 2017, the eight antennas of the EHT, which are distributed around the globe, also collected data from Centaurus A. After the complex analysis, the core region of the galaxy now appears in previously unattained detail. “This allows us for the first time to study an extragalactic radio jet on scales smaller than the distance light travels in a day”, says team leader Michael Janssen of the Max Planck Institute for Radio Astronomy in Bonn and Radboud University Nijmegen. “We see first-hand, how a massive jet is born from a supermassive black hole”.

Centaurus A had already been thoroughly scanned once: at a wavelength of one millimetre by both the Atacama Pathfinder Experiment (APEX) and the South Pole Telescope (STP) in January 2015. “These ground-breaking measurements – from which we were able to estimate the compactness of the nucleus – paved the way for the picture we have now obtained by using the complete EHT network”, says Eduardo Ros of the Max Planck Institute for Radio Astronomy.

In terms of sharpness, the measurement with the EHT at a wavelength of 1.3 millimetres surpasses all previous observations many times over. The origin of the jet near the black hole at an angle corresponds to the size of an apple on the moon – a magnification factor of one billion. This is made possible by a special method called Very Long Baseline Interferometry (VLBI). The signals that the different observatories receive from one and the same object at the same time are superimposed. The resolving power of such a “virtual antenna” is similar to that of an earth-sized radio telescope.

The top left image shows how the jet disperses into gas clouds that emit radio waves, captured by the ATCA and Parkes observatories. The top right panel displays a color composite image, with a 40x zoom compared to the first panel to match the size of the galaxy itself. Submillimeter emission from the jet and dust in the galaxy measured by the LABOCA/APEX instrument is shown in orange. X-ray emission from the jet measured by the Chandra spacecraft is shown in blue. Visible white light from the stars in the galaxy has been captured by the MPG/ESO 2.2-metre telescope. The next panel below shows a 165000x zoom image of the inner radio jet obtained with the TANAMI telescopes. The bottom panel depicts the new highest resolution image of the jet launching region obtained with the EHT at millimeter wavelengths with a 60000000x zoom in telescope resolution. Indicated scale bars are shown in light years and light days. One light year is equal to the distance that light travels within one year: about nine trillion kilometers. In comparison, the distance to the nearest-known star from our Sun is approximately four light years. One light day is equal to the distance that light travels within one day: about six times the distance between the Sun and Neptune. © Radboud University; CSIRO/ATNF/I.Feain et al., R.Morganti et al., N.Junkes et al.; ESO/WFI; MPIfR/ESO/APEX/A. Weiss et al.; NASA/CXC/CfA/R. Kraft et al.; TANAMI/C. Mueller et al.; EHT/M. Janssen et al.

Super-massive black holes located at the centres of active galaxies like Centaurus A exert an almost irresistible pull on their surroundings. They feed on gas and dust and release huge amounts of energy during their “meal”. Most of the matter near the edge of a black hole falls into the cosmic void. However, some of the surrounding particles escape just before capture. This creates “jets”, the mechanism of which is still a mystery.

Researchers are using different models to try to explain exactly how matter behaves near a black hole. But how are the jets launched from the galactic centres? And how can they extend many thousands of light years out into space, far surpassing their host galaxies in size? The EHT aims to help answer these questions.

For example, the new image shows that the jet originating in the interior of Centaurus A is brighter at the edges than in the centre. Scientists know this phenomenon from other jets. But it had never been observed quite so clearly. “With this striking feature, we can now rule out all theoretical jet models from which no such edge brightening results”, says Matthias Kadler, an astrophysicist at the University of Würzburg.

In addition, the EHT measurements have identified the likely position of the black hole at the starting point of the jet. Based on this finding, the researchers predict that future observations at even shorter wavelengths and higher detail resolution will make it possible to depict the black hole at the heart of Centaurus A – analogous to that in the giant galaxy M 87.

“The EHT allows us to not only look at the shadows of black holes but also investigate the origin of the giant jets of matter in galaxies”, says Anton Zensus, Director at the Max Planck Institute for Radio Astronomy and founding chair of the EHT collaboration. “In the jets emerging from the immediate vicinity of the black hole, relativity and magnetic fields interact”.

According to Zensus, research with the EHT will now focus more on the magnetic fields at the heart of radio galaxies and quasars – young, active star systems. “I am sure that we will soon master the improved methods needed to evaluate the new observations”.

Featured image: Close-up: The image shows the launch region of the jet in the radio galaxy Centaurus A, taken with the Event Horizon Telescope at a wavelength of 1.3 millimetres. The bar corresponds to the distance that light travels within one day. In our planetary system, this is about six times the distance between the Sun and Neptune. © EHT-Kollaboration / M. Janssen et al.


Reference: Janssen, M., Falcke, H., Kadler, M. et al. Event Horizon Telescope observations of the jet launching and collimation in Centaurus A. Nat Astron (2021). Link https://doi.org/10.1038/s41550-021-01417-w


Provided by Max Planck Gesellschaft