Making Seawater Drinkable in Minutes: A New Alternative Desalination Membrane

Schematic of co-axial electrospinning device. Credit: Elsevier

A new alternative seawater desalination membrane to produce drinking water.

According to the World Health Organization, about 785 million people around the world lack a clean source of drinking water. Despite the vast amount of water on Earth, most of it is seawater and freshwater accounts for only about 2.5% of the total. One of the ways to provide clean drinking water is to desalinate seawater. The Korea Institute of Civil Engineering and Building Technology (KICT) has announced the development of a stable performance electrospun nanofiber membrane to turn seawater into drinking water by membrane distillation process.

Membrane wetting is the most challenging issue in membrane distillation. If a membrane exhibits wetting during membrane distillation operation, the membrane must be replaced. Progressive membrane wetting has been especially observed for long-term operations. If a membrane gets fully wetted, the membrane leads to inefficient membrane distillation performance, as the feed flow through the membrane leading to low-quality permeate.

A research team in KICT, led by Dr. Yunchul Woo, has developed co-axial electrospun nanofiber membranes fabricated by an alternative nano-technology, which is electrospinning. This new desalination technology shows it has the potential to help solve the world’s freshwater shortage. The developed technology can prevent wetting issues and also improve the long-term stability in membrane distillation process. A three-dimensional hierarchical structure should be formed by the nanofibers in the membranes for higher surface roughness and hence better hydrophobicity.

Merits of co-axial electrospun nanofiber membrane. Credit: Elsevier

The co-axial electrospinning technique is one of the most favorable and simple options to fabricate membranes with three-dimensional hierarchical structures. Dr. Woo’s research team used poly(vinylidene fluoride-co-hexafluoropropylene) as the core and silica aerogel mixed with a low concentration of the polymer as the sheath to produce a co-axial composite membrane and obtain a superhydrophobic membrane surface. In fact, silica aerogel exhibited a much lower thermal conductivity compared with that of conventional polymers, which led to increased water vapor flux during the membrane distillation process due to a reduction of conductive heat losses.

Most of the studies using electrospun nanofiber membranes in membrane distillation applications operated for less than 50 hours although they exhibited a high water vapor flux performance. On the contrary, Dr. Woo’s research team applied the membrane distillation process using the fabricated co-axial electrospun nanofiber membrane for 30 days, which is 1 month.

The co-axial electrospun nanofiber membrane performed a 99.99% salt rejection for 1 month. Based on the results, the membrane operated well without wetting and fouling issues, due to its low sliding angle and thermal conductivity properties. Temperature polarization is one of the significant drawbacks in membrane distillation. It can decrease water vapor flux performance during membrane distillation operation due to conductive heat losses. The membrane is suitable for long-term membrane distillation applications as it possesses several important characteristics such as, low sliding angle, low thermal conductivity, avoiding temperature polarization, and reduced wetting and fouling problems whilst maintaining super-saturated high water vapor flux performance.

Dr. Woo’s research team noted that it is more important to have a stable process than a high water vapor flux performance in a commercially available membrane distillation process. Dr. Woo said that “the co-axial electrospun nanofiber membrane have strong potential for the treatment of seawater solutions without suffering from wetting issues and may be the appropriate membrane for pilot-scale and real-scale membrane distillation applications.”

Reference: “Co-axially electrospun superhydrophobic nanofiber membranes with 3D-hierarchically structured surface for desalination by long-term membrane distillation” by Yun Chul Woo, Minwei Yao, Wang-Geun Shim, Youngjin Kim, Leonard D. Tijing, Bumsuk Jung, Seung-Hyun Kim and Ho Kyong Shon, 4 January 2021, Journal of Membrane Science.
DOI: 10.1016/j.memsci.2020.119028

The Korea Institute of Civil Engineering and Building Technology (KICT) is a government-sponsored research institute established to contribute to the development of Korea’s construction industry and national economic growth by developing source and practical technology in the fields of construction and national land management.

This research was supported by an internal grant (20200543-001) from the KICT, Republic of Korea. The outcomes of this project were published in the international journal, Journal of Membrane Science, a renowned international journal in the polymer science field (IF: 7.183 and Rank #3 of the JCR category) in April 2021.

Analysis of Thousands of Drugs Reveals Potential New COVID-19 Antivirals

Researchers at the Francis Crick Institute and University of Dundee have screened thousands of drug and chemical molecules and identified a range of potential antivirals that could be developed into new treatments for COVID-19 or in preparation for future coronavirus outbreaks.

While COVID-19 vaccines are being rolled out, there are still few drug options that can be used to treat patients with the virus, to reduce symptoms and speed up recovery time. These treatments are especially important for groups where the vaccines are less effective, such as some patients with blood cancers.

In a series of seven papers, published today (July 2, 2021) in the Biochemical Journal, the scientists identified 15 molecules which inhibit the growth of SARS-CoV-2 by blocking different enzymes involved in its replication.

The researchers developed and ran tests for around 5,000 molecules provided by the Crick’s High Throughput Screening team to see if any of these effectively blocked the functioning of any of seven SARS-CoV-2 enzymes. The tests were based on fluorescent changes with a special imaging tool detecting if enzymes had been affected.

They then validated and tested the potential inhibitors against SARS-CoV-2 in the lab, to determine if they effectively slowed viral growth. The team found at least one inhibitor for all seven enzymes.

Three of the molecules identified are existing drugs, used to treat other diseases. Lomeguatrib is used in melanoma and has few side-effects, suramin is a treatment for African sleeping sickness and river blindness and trifluperidol is used in cases of mania and schizophrenia. As there is existing safety data on these drugs, it may be possible to more quickly develop these into SARS-CoV-2 antivirals.

John Diffley, lead author of the papers and associate research director and head of the Chromosome Replication Laboratory at the Crick, said: “We’ve developed a chemical toolbox of information about potential new COVID-19 drugs. We hope this attracts attention from scientists with the drug development and clinical expertise needed to test these further, and ultimately see if any could become safe and effective treatments for COVID-19 patients.”

The 15 molecules were also tested in combination with remdesivir, an antiviral being used to treat patients with COVID-19. Four of these, all which target the SARS-CoV-2 enzyme Nsp14 mRNA Cap methyltransferase, were found to improve the effectiveness of this antiviral in lab tests.

The scientists now plan to run tests to see if any pairing of the 15 molecules they identified decrease the virus’ growth more than if they are used alone. Targeting enzymes involved in virus replication could also help prepare for future viral pandemics.

“Proteins on the outside of viruses evolve rapidly but within different classes of viruses are well conserved proteins that change very little with time,” adds John.

“If we can develop drugs that inhibit these proteins, in the situation of a future pandemic, they could provide a valuable first line of defense, before vaccines become available.”

References:

“Identification of SARS-CoV-2 Antiviral Compounds by Screening for Small Molecule Inhibitors of the nsp14 RNA Cap Methyltransferase” by Basu, S. et al., 2 July 2021, Biochemical Journal.
DOI: 10.1042/BCJ20210219

“Identifying SARS-CoV-2 Antiviral Compounds by Screening for Small Molecule Inhibitors of nsp5 Main Protease” by Milligan, J. et al., 2 July 2021, Biochemical Journal.
DOI: 10.1042/BCJ20210197

“Identifying SARS-CoV-2 Antiviral Compounds by Screening for Small Molecule Inhibitors of Nsp12/7/8 RNA-dependent RNA Polymerase” by Bertolin, A. et al., 2 July 2021, Biochemical Journal.
DOI: 10.1042/BCJ20210200

“Identifying SARS-CoV-2 Antiviral Compounds by Screening for Small Molecule Inhibitors of Nsp13 Helicase” by Zeng, J. et al., 2 July 2021, Biochemical Journal.
DOI: 10.1042/BCJ20210201

“Identifying SARS-CoV-2 Antiviral Compounds by Screening for Small Molecule Inhibitors of Nsp3 Papain-like Protease” by Lim, CT. et al., 2 July 2021, Biochemical Journal.
DOI: 10.1042/BCJ20210244

“Identifying SARS-CoV-2 Antiviral Compounds by Screening for Small Molecule Inhibitors of Nsp15 Endoribonuclease” by Canal, B. et al., 2 July 2021, Biochemical Journal.
DOI: 10.1042/BCJ20210199

“Identifying SARS-CoV-2 Antiviral Compounds by Screening for Small Molecule Inhibitors of Nsp14/nsp10 Exoribonuclease” by Canal, B. et al., 2 July 2021, Biochemical Journal.
DOI: 10.1042/BCJ20210198

The Francis Crick Institute is a biomedical discovery institute dedicated to understanding the fundamental biology underlying health and disease. Its work is helping to understand why disease develops and to translate discoveries into new ways to prevent, diagnose and treat illnesses such as cancer, heart disease, stroke, infections, and neurodegenerative diseases.

An independent organization, its founding partners are the Medical Research Council (MRC), Cancer Research UK, Wellcome, UCL (University College London), Imperial College London, and King’s College London.

The Crick was formed in 2015, and in 2016 it moved into a brand new state-of-the-art building in central London which brings together 1500 scientists and support staff working collaboratively across disciplines, making it the biggest biomedical research facility under a single roof in Europe.

Hawking’s Black Hole Theorem Confirmed Observationally for the First Time

An artist’s impression of two black holes about to collide and merge.

Study offers evidence, based on gravitational waves, to show that the total area of a black hole’s event horizon can never decrease.

There are certain rules that even the most extreme objects in the universe must obey. A central law for black holes predicts that the area of their event horizons — the boundary beyond which nothing can ever escape — should never shrink. This law is Hawking’s area theorem, named after physicist Stephen Hawking, who derived the theorem in 1971.

Fifty years later, physicists at MIT and elsewhere have now confirmed Hawking’s area theorem for the first time, using observations of gravitational waves. Their results appear today (July 1, 2021) in Physical Review Letters.

In the study, the researchers take a closer look at GW150914, the first gravitational wave signal detected by the Laser Interferometer Gravitational-wave Observatory (LIGO), in 2015. The signal was a product of two inspiraling black holes that generated a new black hole, along with a huge amount of energy that rippled across space-time as gravitational waves.

If Hawking’s area theorem holds, then the horizon area of the new black hole should not be smaller than the total horizon area of its parent black holes. In the new study, the physicists reanalyzed the signal from GW150914 before and after the cosmic collision and found that indeed, the total event horizon area did not decrease after the merger — a result that they report with 95 percent confidence.

Physicists at MIT and elsewhere have used gravitational waves to observationally confirm Hawking’s black hole area theorem for the first time. This computer simulation shows the collision of two black holes that produced the gravitational wave signal, GW150914. Credit: Simulating eXtreme Spacetimes (SXS) project. Credit: Courtesy of LIGO

Their findings mark the first direct observational confirmation of Hawking’s area theorem, which has been proven mathematically but never observed in nature until now. The team plans to test future gravitational-wave signals to see if they might further confirm Hawking’s theorem or be a sign of new, law-bending physics.

“It is possible that there’s a zoo of different compact objects, and while some of them are the black holes that follow Einstein and Hawking’s laws, others may be slightly different beasts,” says lead author Maximiliano Isi, a NASA Einstein Postdoctoral Fellow in MIT’s Kavli Institute for Astrophysics and Space Research. “So, it’s not like you do this test once and it’s over. You do this once, and it’s the beginning.”

Isi’s co-authors on the paper are Will Farr of Stony Brook University and the Flatiron Institute’s Center for Computational Astrophysics, Matthew Giesler of Cornell University, Mark Scheel of Caltech, and Saul Teukolsky of Cornell University and Caltech.

An age of insights

In 1971, Stephen Hawking proposed the area theorem, which set off a series of fundamental insights about black hole mechanics. The theorem predicts that the total area of a black hole’s event horizon — and all black holes in the universe, for that matter — should never decrease. The statement was a curious parallel of the second law of thermodynamics, which states that the entropy, or degree of disorder within an object, should also never decrease.

The similarity between the two theories suggested that black holes could behave as thermal, heat-emitting objects — a confounding proposition, as black holes by their very nature were thought to never let energy escape, or radiate. Hawking eventually squared the two ideas in 1974, showing that black holes could have entropy and emit radiation over very long timescales if their quantum effects were taken into account. This phenomenon was dubbed “Hawking radiation” and remains one of the most fundamental revelations about black holes.

“It all started with Hawking’s realization that the total horizon area in black holes can never go down,” Isi says. “The area law encapsulates a golden age in the ’70s where all these insights were being produced.”

Hawking and others have since shown that the area theorem works out mathematically, but there had been no way to check it against nature until LIGO’s first detection of gravitational waves.

Hawking, on hearing of the result, quickly contacted LIGO co-founder Kip Thorne, the Feynman Professor of Theoretical Physics at Caltech. His question: Could the detection confirm the area theorem?

At the time, researchers did not have the ability to pick out the necessary information within the signal, before and after the merger, to determine whether the final horizon area did not decrease, as Hawking’s theorem would assume. It wasn’t until several years later, and the development of a technique by Isi and his colleagues, when testing the area law became feasible.

Before and after

In 2019, Isi and his colleagues developed a technique to extract the reverberations immediately following GW150914’s peak — the moment when the two parent black holes collided to form a new black hole. The team used the technique to pick out specific frequencies, or tones of the otherwise noisy aftermath, that they could use to calculate the final black hole’s mass and spin.

A black hole’s mass and spin are directly related to the area of its event horizon, and Thorne, recalling Hawking’s query, approached them with a follow-up: Could they use the same technique to compare the signal before and after the merger, and confirm the area theorem?

The researchers took on the challenge, and again split the GW150914 signal at its peak. They developed a model to analyze the signal before the peak, corresponding to the two inspiraling black holes, and to identify the mass and spin of both black holes before they merged. From these estimates, they calculated their total horizon areas — an estimate roughly equal to about 235,000 square kilometers, or roughly nine times the area of Massachusetts.

They then used their previous technique to extract the “ringdown,” or reverberations of the newly formed black hole, from which they calculated its mass and spin, and ultimately its horizon area, which they found was equivalent to 367,000 square kilometers (approximately 13 times the Bay State’s area).

“The data show with overwhelming confidence that the horizon area increased after the merger, and that the area law is satisfied with very high probability,” Isi says. “It was a relief that our result does agree with the paradigm that we expect, and does confirm our understanding of these complicated black hole mergers.”

The team plans to further test Hawking’s area theorem, and other longstanding theories of black hole mechanics, using data from LIGO and Virgo, its counterpart in Italy.

“It’s encouraging that we can think in new, creative ways about gravitational-wave data, and reach questions we thought we couldn’t before,” Isi says. “We can keep teasing out pieces of information that speak directly to the pillars of what we think we understand. One day, this data may reveal something we didn’t expect.”

Reference: “Testing the Black-Hole Area Law with GW150914” by Maximiliano Isi, Will M. Farr, Matthew Giesler, Mark A. Scheel and Saul A. Teukolsky, 1 July 2021, Physical Review Letters.
DOI: 10.1103/PhysRevLett.127.011103

This research was supported, in part, by NASA, the Simons Foundation, and the National Science Foundation.

Worrying New Insights Into the Chemicals in Plastics – Significant Risk to People and the Environment

Plastic is practical, cheap and incredibly popular. Every year, more than 350 million metric tons are produced worldwide. These plastics contain a huge variety of chemicals that may be released during their lifecycles — including substances that pose a significant risk to people and the environment. However, only a small proportion of the chemicals contained in plastic are publicly known or have been extensively studied.

A team of researchers led by Stefanie Hellweg, ETH Professor of Ecological Systems Design, has for a first time compiled a comprehensive database of plastic monomers, additives and processing aids for use in the production and processing of plastics on the world market, and systematically categorized them on the basis of usage patterns and hazard potential. The study, just published in the scientific journal Environmental Science & Technology, provides an enlightening but worrying insight into the world of chemicals that are intentionally added to plastics.

A high level of chemical diversity

The team identified around 10,500 chemicals in plastic. Many are used in packaging (2,489), textiles (2,429) and food-contact applications (2,109); some are for toys (522) and medical devices, including masks (247). Of the 10,500 substances identified, the researchers categorized 2,480 substances (24 percent) as substances of potential concern.

“This means that almost a quarter of all the chemicals used in plastic are either highly stable, accumulate in organisms or are toxic. These substances are often toxic to aquatic life, cause cancer or damage specific organs,” explains Helene Wiesinger, doctoral student at the Chair of Ecological Systems Design and lead author of the study. About half are chemicals with high production volumes in the EU or the US.

“It is particularly striking that many of the questionable substances are barely regulated or are ambiguously described,” continues Wiesinger.

In fact, 53 percent of all the substances of potential concern are not regulated in the US, the EU or Japan. More surprisingly, 901 hazardous substances are approved for use in food contact plastics in these regions. Finally, scientific studies are lacking for about 10 percent of the identified substances of potential concern.

Plastic monomers, additives and processing aids

Plastics are made of organic polymers built up from repeating monomer units. A wide variety of additives, such as antioxidants, plasticisers and flame retardants, give the polymer matrix the desired properties. Catalysts, solvents and other chemicals are also used as processing aids in production.

“Until now, research, industry and regulators have mainly concentrated on a limited number of dangerous chemicals known to be present in plastics,” says Wiesinger. Today, plastic packaging is seen as a main source of organic contamination in food, while phthalate plasticisers and brominated flame retardants are detectable in house dust and indoor air. Earlier studies have already indicated that significantly more plastic chemicals used worldwide are potentially hazardous.

Nevertheless, the results of the inventory came as an unpleasant surprise to the researchers. “The unexpectedly high number of substances of potential concern is worrying,” says Zhanyun Wang, senior scientist in Hellweg’s group. Exposure to such substances can have a negative impact on the health of consumers and workers and on polluted ecosystems. Problematic chemicals can also affect recycling processes and the safety and quality of recycled plastics.

Wang stresses that even more chemicals in plastics could be problematic. “Recorded hazard data are often limited and scattered. For 4,100 or 39 percent of all the substances we identified, we were not able to categorize them due to a lack of hazard classifications” he says.

A lack of data and transparency

The two researchers identified the lack of transparency in chemicals in plastics and dispersed data silos as a main problem. In over two and a half years of detective work, they combed through more than 190 publicly accessible data sources from research, industry and authorities and identified 60 sources with sufficient information about intentionally added substances in plastics. “We found multiple critical knowledge and data gaps, in particular for the substances and their actual uses. This ultimately hinders consumers’ choice of safe plastic products,” they say.

Wiesinger and Wang are pursuing the goal of a sustainable circular plastic economy. They see an acute need for effective global chemicals management; such a system would have to be transparent and independent, and oversee all hazardous substances in full. The two researchers say that open and easy access to reliable information is crucial.

Reference: “Deep Dive into Plastic Monomers, Additives, and Processing Aids” by Helene Wiesinger, Zhanyun Wang and Stefanie Hellweg, 21 June 2021, Environmental Science and Technology.
DOI: 10.1021/acs.est.1c00976

Optical Tweezer Technology Breakthrough Overcomes Dangers of Heat

Optical tweezers use light to trap particles for analysis. A new breakthrough keeps those particles from overheating. Credit: The University of Texas at Austin

Three years ago, Arthur Ashkin won the Nobel Prize for inventing optical tweezers, which use light in the form of a high-powered laser beam to capture and manipulate particles. Despite being created decades ago, optical tweezers still lead to major breakthroughs and are widely used today to study biological systems.

However, optical tweezers do have flaws. The prolonged interaction with the laser beam can alter molecules and particles or damage them with excessive heat.

Researchers at The University of Texas at Austin have created a new version of optical tweezer technology that fixes this problem, a development that could open the already highly regarded tools to new types of research and simplify processes for using them today.

The breakthrough that avoids this problem of overheating comes out of a combination of two concepts: the use of a substrate composed of materials that are cooled when a light is shined on them (in this case, a laser); and a concept called thermophoresis, a phenomenon in which mobile particles will commonly gravitate toward a cooler environment.

The cooler materials attract particles, making them easier to isolate, while also protecting them from overheating. By solving the heat problem, optical tweezers could become more widely used to study biomolecules, DNA, diseases and more.

“Optical tweezers have many advantages, but they are limited because whenever the light captures objects, they heat up,” said Yuebing Zheng, the corresponding author of a new paper published in Science Advances and an associate professor in the Walker Department of Mechanical Engineering. “Our tool addresses this critical challenge; instead of heating the trapped objects, we have them controlled at a lower temperature.”

Optical tweezers do the same thing as regular tweezers — pick up small objects and manipulate them. However, optical tweezers work at a much smaller scale and use light to capture and move objects.

Analyzing DNA is a common use of optical tweezers. But doing so requires attaching nano-sized glass beads to the particles. Then to move the particles, the laser is shined on the beads, not the particles themselves, because the DNA would be damaged by the heating effect of the light.

“When you are forced to add more steps to the process, you increase uncertainty because now you have introduced something else into the biological system that may impact it,” Zheng said.

This new and improved version of optical tweezers eliminates these extra steps.

The team’s next steps include developing autonomous control systems, making them easier for people without specialized training to use and extending the tweezers’ capabilities to handle biological fluids such as blood and urine. And they are working to commercialize the discovery.

Zheng and his team have much variety in their research, but it all centers on light and how it interacts with materials. Because of this focus on light, he has closely followed, and used, optical tweezers in his research. The researchers were familiar with thermophoresis and hoped they could trigger it with cooler materials, which would actually draw particles to the laser to simplify analysis.

Reference: “Opto-refrigerative tweezers” by Jingang Li, Zhihan Chen, Yaoran Liu, Pavana Siddhartha Kollipara, Yichao Feng, Zhenglong Zhang and Yuebing Zheng, 25 June 2021, Science Advances.
DOI: 10.1126/sciadv.abh1101

This research was supported by grants from the National Institutes of Health’s National Institute of General Medical Sciences and the National Science Foundation. Other authors are Jingang Li and Zhihan Chen of UT’s Texas Materials Institute; Yaoran Liu of the Department of Electrical and Computer Engineering; Pavana Siddhartha Kollipara of the Walker Department of Mechanical Engineering; and Yichao Feng and Zhenglong Zhang of Shaanxi Normal University’s School of Physics and Information in China.

Uncovering Genetic Traces to Discover How Humans Adapted to Historical Coronavirus Outbreaks

Coronavirus graphic. Credit: Gerd Altmann

An international team of researchers co-led by the University of Adelaide and the University of Arizona has analyzed the genomes of more than 2,500 modern humans from 26 worldwide populations, to better understand how humans have adapted to historical coronavirus outbreaks.

In a paper published in Current Biology, the researchers used cutting-edge computational methods to uncover genetic traces of adaptation to coronaviruses, the family of viruses responsible for three major outbreaks in the last 20 years, including the ongoing pandemic.

“Modern human genomes contain evolutionary information tracing back hundreds of thousands of years, however, it’s only in the past few decades geneticists have learned how to decode the extensive information captured within our genomes,” said lead author Dr. Yassine Souilmi, with the University of Adelaide’s School of Biological Sciences.

“This includes physiological and immunological ‘adaptions’ that have enabled humans to survive new threats, including viruses.

“Viruses are very simple creatures with the sole objective to make more copies of themselves. Their simple biological structure renders them incapable of reproducing by themselves so they must invade the cells of other organisms and hijack their molecular machinery to exist.”

Lead author Dr. Yassine Souilmi Australian Centre for Ancient DNA, School of Biological Sciences, The University of Adelaide. Credit: The University of Adelaide

Viral invasions involve attaching and interacting with specific proteins produced by the host cell known as viral interacting proteins (VIPs).

In the study, researchers found signs of adaptation in 42 different human genes encoding VIPs.

“We found VIP signals in five populations from East Asia and suggest the ancestors of modern East Asians were first exposed to coronaviruses over 20,000 years ago,” said Dr. Souilmi.

“We found the 42 VIPs are primarily active in the lungs — the tissue most affected by coronaviruses — and confirmed that they interact directly with the virus underlying the current pandemic.”

Dr. Ray Tobler, Australian Centre for Ancient DNA, within the University of Adelaide’s School of Biological Sciences. Credit: The University of Adelaide

Other independent studies have shown that mutations in VIP genes may mediate coronavirus susceptibility and also the severity of COVID-19 symptoms. And several VIPs are either currently being used in drugs for COVID-19 treatments or are part of clinical trials for further drug development.

“Our past interactions with viruses have left telltale genetic signals that we can leverage to identify genes influencing infection and disease in modern populations, and can inform drug repurposing efforts and the development of new treatments,” said co-author Dr. Ray Tobler, from the University of Adelaide’s School of Biological Sciences.

“By uncovering the genes previously impacted by historical viral outbreaks, our study points to the promise of evolutionary genetic analyses as a new tool in fighting the outbreaks of the future,” said Dr. Souilmi.

The researchers also note that their results in no way supersede pre-existing public health policies and protections, such as mask-wearing, social distancing, and vaccinations.

Reference: “An ancient viral epidemic involving host coronavirus interacting genes more than 20,000 years ago in East Asia” by Yassine Souilmi, M. Elise Lauterbur, Ray Tobler, Christian D. Huber, Angad S. Johar, Shayli Varasteh Moradi, Wayne A. Johnston, Nevan J. Krogan, Kirill Alexandrov and David Enard, 24 June 2021, Current Biology.
DOI: 10.1016/j.cub.2021.05.067

The team involved in this study also included researchers from Australian National University and Queensland University of Technology.

Scientists Can Now Design Single Atom Catalysts for Important Chemical Reactions

Artistic rendering of the propane dehydrogenation process taking place on the novel single atom alloy catalyst, as predicted by theory. The picture shows the transition state obtained from a quantum chemistry calculation on a supercomputer, i.e. the molecular configuration of maximum energy along the reaction path. Credit: Charles Sykes & Michail Stamatakis

Using fundamental calculations of molecular interactions, they created a catalyst with 100% selectivity in producing propylene, a key precursor to plastics and fabric manufacturing.

Researchers at Tufts University, University College London (UCL), Cambridge University and University of California at Santa Barbara have demonstrated that a catalyst can indeed be an agent of change. In a study published today in Science, they used quantum chemical simulations run on supercomputers to predict a new catalyst architecture as well as its interactions with certain chemicals, and demonstrated in practice its ability to produce propylene – currently in short supply – which is critically needed in the manufacture of plastics, fabrics and other chemicals. The improvements have potential for highly efficient, “greener” chemistry with a lower carbon footprint.

The demand for propylene is about 100 million metric tons per year (worth about $200 billion), and there is simply not enough available at this time to meet surging demand. Next to sulfuric acid and ethylene, its production involves the third largest conversion process in the chemical industry by scale. The most common method for producing propylene and ethylene is steam cracking, which has a yield limited to 85% and is one of the most energy intensive processes in the chemical industry. The traditional feedstocks for producing propylene are by-products from oil and gas operations, but the shift to shale gas has limited its production.

Typical catalysts used in the production of propylene from propane found in shale gas are made up of combinations of metals that can have a random, complex structure at the atomic level. The reactive atoms are usually clustered together in many different ways making it difficult to design new catalysts for reactions, based on fundamental calculations on how the chemicals might interact with the catalytic surface.

By contrast, single-atom alloy catalysts, discovered at Tufts University and first reported in Science in 2012, disperse single reactive metal atoms in a more inert catalyst surface, at a density of about 1 reactive atom to 100 inert atoms. This enables a well-defined interaction between a single catalytic atom and the chemical being processed without being compounded by extraneous interactions with other reactive metals nearby. Reactions catalyzed by single-atom alloys tend to be clean and efficient, and, as demonstrated in the current study, they are now predictable by theorical methods.

“We took a new approach to the problem by using first principles calculations run on supercomputers with our collaborators at University College London and Cambridge University, which enabled us to predict what the best catalyst would be for converting propane into propylene,” said Charles Sykes, the John Wade Professor in the Department of Chemistry at Tufts University and corresponding author of the study.

These calculations which led to predictions of reactivity on the catalyst surface were confirmed by atomic-scale imaging and reactions run on model catalysts. The researchers then synthesized single-atom alloy nanoparticle catalysts and tested them under industrially relevant conditions. In this particular application, rhodium (Rh) atoms dispersed on a copper (Cu) surface worked best to dehydrogenate propane to make propylene.

“Improvement of commonly used heterogeneous catalysts has mostly been a trial-and-error process,” said Michail Stamatakis, associate professor of chemical engineering at UCL and co-corresponding author of the study. “The single-atom catalysts allow us to calculate from first principles how molecules and atoms interact with each other at the catalytic surface, thereby predicting reaction outcomes. In this case, we predicted rhodium would be very effective at pulling hydrogens off molecules like methane and propane – a prediction that ran counter to common wisdom but nevertheless turned out to be incredibly successful when put into practice. We now have a new method for the rational design of catalysts.”

The single atom Rh catalyst was highly efficient, with 100% selective production of the product propylene, compared to 90% for current industrial propylene production catalysts, where selectivity refers to the proportion of reactions at the surface that leads to the desired product. “That level of efficiency could lead to large cost savings and millions of tons of carbon dioxide not being emitted into the atmosphere if it’s adopted by industry,” said Sykes.

Not only are the single atom alloy catalysts more efficient, but they also tend to run reactions under milder conditions and lower temperatures and thus require less energy to run than conventional catalysts. They can be cheaper to produce, requiring only a small fraction of precious metals like platinum or rhodium, which can be very expensive. For example, the price of rhodium is currently around $22,000 per ounce, while copper, which comprises 99% of the catalyst, costs just 30 cents an ounce. The new rhodium/copper single-atom alloy catalysts are also resistant to coking – a ubiquitous problem in industrial catalytic reactions in which high carbon content intermediates — basically, soot — build up on the surface of the catalyst and begin inhibiting the desired reactions. These improvements are a recipe for “greener” chemistry with a lower carbon footprint.

“This work further demonstrates the great potential of single-atom alloy catalysts for addressing inefficiencies in the catalyst industry, which in turn has very large economic and environmental payoffs,” said Sykes.

Reference: “First-principles design of a single-atom–alloy propane dehydrogenation catalyst” by Ryan T. Hannagan, Georgios Giannakakis, Romain Réocreux, Julia Schumann, Jordan Finzel, Yicheng Wang, Angelos Michaelides, Prashant Deshlahra, Phillip Christopher, Maria Flytzani-Stephanopoulos, Michail Stamatakis and E. Charles H. Sykes, 25 June 2021, Science.
DOI: 10.1126/science.abg8389

Are We Missing Other Earths? Dramatic New Evidence Uncovered by Astronomers

This illustration depicts a planet partially hidden in the glare of its host star and a nearby companion star. After examining a number of binary stars, astronomers have concluded that Earth-sized planets in many two-star systems might be going unnoticed by transit searches, which look for changes in the light from a star when a planet passes in front of it. The light from the second star makes it more difficult to detect the changes in the host star’s light when the planet passes in front of it. Credit: International Gemini Observatory/NOIRLab/NSF/AURA/J. da Silva

Astronomers studying stellar pairs uncover evidence that there could be many more Earth-sized planets than previously thought.

Some exoplanet searches could be missing nearly half of the Earth-sized planets around other stars. New findings from a team using the international Gemini Observatory and the WIYN 3.5-meter Telescope at Kitt Peak National Observatory suggest that Earth-sized worlds could be lurking undiscovered in binary star systems, hidden in the glare of their parent stars. As roughly half of all stars are in binary systems, this means that astronomers could be missing many Earth-sized worlds.

Earth-sized planets may be much more common than previously realized. Astronomers working at NASA Ames Research Center have used the twin telescopes of the international Gemini Observatory, a Program of NSF’s NOIRLab, to determine that many planet-hosting stars identified by NASA’s TESS exoplanet-hunting mission^[1] are actually pairs of stars — known as binary stars — where the planets orbit one of the stars in the pair. After examining these binary stars, the team has concluded that Earth-sized planets in many two-star systems might be going unnoticed by transit searches like TESS’s, which look for changes in the light from a star when a planet passes in front of it.^[2] The light from the second star makes it more difficult to detect the changes in the host star’s light when the planet transits.

The team started out by trying to determine whether some of the exoplanet host stars identified with TESS were actually unknown binary stars. Physical pairs of stars that are close together can be mistaken for single stars unless they are observed at extremely high resolution. So the team turned to both Gemini telescopes to inspect a sample of exoplanet host stars in painstaking detail. Using a technique called speckle imaging,^[3] the astronomers set out to see whether they could spot undiscovered stellar companions.

Using the `Alopeke and Zorro instruments on the Gemini North and South telescopes in Chile and Hawai‘i, respectively,^[4] the team observed hundreds of nearby stars that TESS had identified as potential exoplanet hosts. They discovered that 73 of these stars are really binary star systems that had appeared as single points of light until observed at higher resolution with Gemini. “With the Gemini Observatory’s 8.1-meter telescopes, we obtained extremely high-resolution images of exoplanet host stars and detected stellar companions at very small separations,” said Katie Lester of NASA’s Ames Research Center, who led this work.

Lester’s team also studied an additional 18 binary stars previously found among the TESS exoplanet hosts using the NN-EXPLORE Exoplanet and Stellar Speckle Imager (NESSI) on the WIYN 3.5-meter Telescope at Kitt Peak National Observatory, also a Program of NSF’s NOIRLab.

After identifying the binary stars, the team compared the sizes of the detected planets in the binary star systems to those in single-star systems. They realized that the TESS spacecraft found both large and small exoplanets orbiting single stars, but only large planets in binary systems.

These results imply that a population of Earth-sized planets could be lurking in binary systems and going undetected using the transit method employed by TESS and many other planet-hunting telescopes. Some scientists had suspected that transit searches might be missing small planets in binary systems, but the new study provides observational support to back it up and shows which sizes of exoplanets are affected.^[5]

“We have shown that it is more difficult to find Earth-sized planets in binary systems because small planets get lost in the glare of their two parent stars,” Lester stated. “Their transits are ‘filled in’ by the light from the companion star,” added Steve Howell of NASA’s Ames Research Center, who leads the speckle imaging effort and was involved in this research.

“Since roughly 50% of stars are in binary systems, we could be missing the discovery of — and the chance to study — a lot of Earth-like planets,” Lester concluded.

The possibility of these missing worlds means that astronomers will need to use a variety of observational techniques before concluding that a given binary star system has no Earth-like planets. “Astronomers need to know whether a star is single or binary before they claim that no small planets exist in that system,” explained Lester. “If it’s single, then you could say that no small planets exist. But if the host is in a binary, you wouldn’t know whether a small planet is hidden by the companion star or does not exist at all. You would need more observations with a different technique to figure that out.”

As part of their study, Lester and her colleagues also analyzed how far apart the stars are in the binary systems where TESS had detected large planets. The team found that the stars in the exoplanet-hosting pairs were typically farther apart than binary stars not known to have planets.^[6] This could suggest that planets do not form around stars that have close stellar companions.

“This speckle imaging survey illustrates the critical need for NSF telescope facilities to characterize newly discovered planetary systems and develop our understanding of planetary populations,” said National Science Foundation Division of Astronomical Sciences Program Officer Martin Still.

“This is a major finding in exoplanet work,” Howell commented. “The results will help theorists create their models for how planets form and evolve in double-star systems.”

Notes

1. TESS is the Transiting Exoplanet Survey Satellite, a NASA mission designed to search for planets orbiting other stars in a survey of around 75% of the entire night sky. The mission launched in 2018 and has detected more than 3500 candidate exoplanets, of which more than 130 have been confirmed. The satellite looks for exoplanets by observing their host stars; a transiting exoplanet causes a subtle but measurable dip in the brightness of its host star as it crosses in front of the star and blocks some of its light.
2. The transit technique is one way of discovering exoplanets. It involves looking for regular decreases in the light of a star that could be caused by a planet passing in front of or “transiting” the star and blocking some of the starlight.
3. Speckle imaging is an astronomical technique that allows astronomers to see past the blur of the atmosphere by taking many quick observations in rapid succession. By combining these observations, it is possible to cancel out the blurring effect of the atmosphere, which affects ground-based astronomy by causing stars in the night sky to twinkle.
4. `Alopeke & Zorro are identical imaging instruments permanently mounted on the Gemini North and South telescopes. Their names mean “fox” in Hawaiian and Spanish, respectively, reflecting their respective locations on Maunakea in Hawaiʻi and on Cerro Pachón in Chile.
5. The team found that planets twice the size of Earth or smaller could not be detected using the transit method when observing binary systems.
6. Lester’s team found that the exoplanet-hosting binary stars they identified had average separations of about 100 astronomical units. (An astronomical unit is the average distance between the Sun and Earth.) Binary stars that are not known to host planets are typically separated by around 40 astronomical units.
   More information

This research is presented in the paper “Speckle Observations of TESS Exoplanet Host Stars. II. Stellar Companions at 1-1000 AU and Implications for Small Planet Detection” to appear in the Astronomical Journal.

Reference: “Speckle Observations of TESS Exoplanet Host Stars. II. Stellar Companions at 1-1000 AU and Implications for Small Planet Detection” by Kathryn V. Lester, Rachel A. Matson, Steve B. Howell, Elise Furlan, Crystal L. Gnilka, Nicholas J. Scott, David R. Ciardi, Mark E. Everett, Zachary D. Hartman and Lea A. Hirsch, Accepted, Astronomical Journal.
arXiv:2106.13354

The team is composed of Kathryn V. Lester (NASA Ames Research Center), Rachel A. Matson (US Naval Observatory), Steve B. Howell (NASA Ames Research Center), Elise Furlan (Exoplanet Science Institute, Caltech), Crystal L. Gnilka (NASA Ames Research Center), Nicholas J. Scott (NASA Ames Research Center), David R. Ciardi (Exoplanet Science Institute, Caltech), Mark E. Everett (NSF’s NOIRLab), Zachary D. Hartman (Lowell Observatory & Department of Physics & Astronomy, Georgia State University), and Lea A. Hirsch (Kavli Institute for Particle Astrophysics and Cosmology, Stanford University).

NSF’s NOIRLab (National Optical-Infrared Astronomy Research Laboratory), the US center for ground-based optical-infrared astronomy, operates the international Gemini Observatory (a facility of NSF, NRC–Canada, ANID–Chile, MCTIC–Brazil, MINCyT–Argentina, and KASI–Republic of Korea), Kitt Peak National Observatory (KPNO), Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and Vera C. Rubin Observatory (operated in cooperation with the Department of Energy’s SLAC National Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona. The astronomical community is honored to have the opportunity to conduct astronomical research on Iolkam Du’ag (Kitt Peak) in Arizona, on Maunakea in Hawai‘i, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence that these sites have to the Tohono O’odham Nation, to the Native Hawaiian community, and to the local communities in Chile, respectively.

Evolutionary Unique: The Natural History and Conservation Importance of Elusive Chinese Mountain Cat

Chinese mountain cat. Credit: Song Dazhao, CFCA

Study highlights the evolutionary uniqueness and premier conservation importance of the elusive Chinese mountain cat.

We know that the domestic cat has distant relatives that roam the earth – lions, tigers, cheetahs, and mountain lions. Less familiar are the 38 distinct species in the Family Felidae, many with strange names like pampas cat, kodkod, and rusty spotted cat. The new field of genomics – the unraveling of DNA genomes of separate species – is resolving old conundrums and revealing new secrets across the history of evolutionarily related species among cats, dogs, bears, and ourselves.

In the largest-ever study undertaken of Chinese cats, genetic detectives highlight the evolutionary uniqueness and premier conservation importance of the elusive Chinese mountain cat (Felis silvestris bieti), found only in the Tibetan plateau of China. Also called Chinese desert cat or Steppe cat, the Chinese mountain cat has a distinctive appearance of sand-colored fur, with faint dark stripes a thick tail, and light blue pupils.

The research is published in Scientific Advances.

This new study compared three different felines living in China: the Chinese mountain cat, Felis silvestris bieti, the Asiatic wildcat Felis silvestris ornata, and feral domestic cats Felis silvestris catus. The Asiatic wildcat has distinguishing spotted coat pattern across a wide range extending from the Caspian Sea in the East through western India and southern Mongolia to parts of western China. Approximately 600 million domestic cats are found across the world.

Chinese mountain cat. Credit: Song Dazhao, CFCA

The study was led by the Laboratory of Genomic Diversity at Peking University in Beijing and supported by an international team including lead genetic researchers at Nova Southeastern University, USA, and in Malaysia. The genomic data resolves a taxonomic classification uncertainty, reveals the timing of evolutionary divergence and pinpoints the prospects for survival of an important endangered species.

Using 270 individual samples, the molecular genetic study finds that the Chinese mountain cat is a unique subspecies of the wide-ranging Wildcat, Felis silvestris. The wildcat species is found throughout Europe, Africa, and much of Western Asia. The Felis silvestris bieti subspecies, however, is found only in China, being adapted to the prey and alpine climate of the Tibetan plateau.

Applying the molecular clock hypotheses, the date of evolutionary split between F. s. bieti and F. s. ornata was an estimated at ~1.5 million years ago while the genetic distance from both to the closest Felis species relative, the black footed cat, Felis nigripes is twice that at 3.0 MY ago. These different times support the classification of F. s. ornata and F. s. bieti as subspecies of Felis silvestris. A closely related subspecies from Central Asia and north Africa, Felis silvestris lybica, is the clear predecessor of the world’s domestic cats, including those throughout China. The cat domestication process happened 10-12,000 years ago in the Near East at around the same time and locale, when humankind ancestors morphed from peripatetic hunter-gatherers to sedentary farmers in the Fertile Crescent region.

The Chinese mountain cat faces several major threats, one from modern agricultural practices that divert precious habitat. A second, more existential threat, is from interbreeding with domestic cats brought by the growing human population in the cat’s limited habitat. And finally, climate change, that may be expanding the range of neighboring wildcats into the mountain cat’s core homeland.

“This study will help conservation scientists to identify threats and decide the best ways to conserve this special cat in its native range,” said Stephen J. O’Brien, Ph.D., a world-renowned geneticist and research scientist at NSU’s Halmos College of Arts and Sciences.

The study solidifies the taxonomic status of the mountain cat, Felis silvestris lybica, through an analysis of the cat’s genome, placing the cat in an evolutionary context relative to other species and subspecies of cats. These arcane taxonomic distinctions are important for conservation because scientists have to be sure they are all talking about the same animal when discussing strategies, and no less important, because legal protections have to be specific to the group in question. Without an agreed-upon taxonomy, legal protections and conservation come to a stop.

Another important result of this study is the finding that domestic cats in China are derived from the same common stock and origin as domestic cats throughout the world, and that there was not an independent origin of domesticity in China. Previous studies have hinted at close associations between early Chinese farming communities and local wild animals, including Asian mountain cats, and that some of these animals may have begun the crossing from the wild to living with people in settled communities.

What the current study shows is that this did not happen with domestic cats; now the focus of research can move to determining – why? Why were some species domesticated in some place but not in others? Why did these processes happen when they did, and what were the conditions obtaining that allowed, maybe even promoted, the integration of wild animals into human societies? Answering these related questions will help us understand the history of early China, indeed helps us understand the history of the ancient anthropocentric world, in more detail.

Reference: “Genomic evidence for the Chinese mountain cat as a wildcat conspecific (Felis silvestris bieti) and its introgression to domestic cats” by He Yu, Yue-Ting Xing, Hao Meng, Bing He, Wen-Jing Li, Xin-Zhang Qi, Jian-You Zhao, Yan Zhuang, Xiao Xu, Nobuyuki Yamaguchi, Carlos A. Driscoll, Stephen J. O’Brien and Shu-Jin Luo, 23 June 2021, Science Advances.
DOI: 10.1126/sciadv.abg0221

Habitable Planets With Earth-Like Biospheres May Be Much Rarer Than Thought

A new analysis of known exoplanets has revealed that Earth-like conditions on potentially habitable planets may be much rarer than previously thought. The work focuses on the conditions required for oxygen-based photosynthesis to develop on a planet, which would enable complex biospheres of the type found on Earth. The study was recently published in the Monthly Notices of the Royal Astronomical Society.

The number of confirmed planets in our own Milky Way galaxy now numbers into the thousands. However, planets that are both Earth-like and in the habitable zone — the region around a star where the temperature is just right for liquid water to exist on the surface — are much less common.

At the moment, only a handful of such rocky and potentially habitable exoplanets are known. However the new research indicates that none of these has the theoretical conditions to sustain an Earth-like biosphere by means of ‘oxygenic’ photosynthesis — the mechanism plants on Earth use to convert light and carbon dioxide into oxygen and nutrients.

Only one of those planets comes close to receiving the stellar radiation necessary to sustain a large biosphere: Kepler-442b, a rocky planet about twice the mass of the Earth, orbiting a moderately hot star around 1,200 light-years away.

An artistic representation of the potentially habitable planet Kepler 422-b (left), compared with Earth (right). Credit: Ph03nix1986 / Wikimedia Commons

The study looked in detail at how much energy is received by a planet from its host star, and whether living organisms would be able to efficiently produce nutrients and molecular oxygen, both essential elements for complex life as we know it, via normal oxygenic photosynthesis.

By calculating the amount of photosynthetically active radiation (PAR) that a planet receives from its star, the team discovered that stars around half the temperature of our Sun cannot sustain Earth-like biospheres because they do not provide enough energy in the correct wavelength range. Oxygenic photosynthesis would still be possible, but such planets could not sustain a rich biosphere.

Planets around even cooler stars known as red dwarfs, which smolder at roughly a third of our Sun’s temperature, could not receive enough energy to even activate photosynthesis. Stars that are hotter than our Sun are much brighter, and emit up to ten times more radiation in the necessary range for effective photosynthesis than red dwarfs, however generally do not live long enough for complex life to evolve.

“Since red dwarfs are by far the most common type of star in our galaxy, this result indicates that Earth-like conditions on other planets may be much less common than we might hope,” comments Prof. Giovanni Covone of the University of Naples, lead author of the study.

He adds: “This study puts strong constraints on the parameter space for complex life, so unfortunately it appears that the “sweet spot” for hosting a rich Earth-like biosphere is not so wide.”

Future missions such as the James Webb Space Telescope (JWST), due for launch later this year, will have the sensitivity to look to distant worlds around other stars and shed new light on what it really takes for a planet to host life as we know it.

Reference: “Efficiency of the oxygenic photosynthesis on Earth-like planets in the habitable zone” by Giovanni Covone, Riccardo M Ienco, Luca Cacciapuoti and Laura Inno, 19 May 2021, Monthly Notices of the Royal Astronomical Society.
DOI: 10.1093/mnras/stab1357

Inkjet Printing “Impossible Materials” – Bend Light, Manipulate Energy, or Have Chameleon-Like Abilities

A thin film polymer tunes the properties of an inkjet printed array of small microwave resonators. The composite device can be tuned to capture or transmit different wavelengths of microwave energy. Credit: Fio Omenetto, Tufts University

Engineers develop inexpensive, scalable method to make metamaterials that manipulate microwave energy in ways conventional materials cannot.

Engineers at Tufts University have developed new methods to more efficiently fabricate materials that behave in unusual ways when interacting with microwave energy, with potential implications for telecommunications, GPS, radar, mobile devices, and medical devices. Known as metamaterials, they are sometimes referred to as “impossible materials” because they could, in theory, bend energy around objects to make them appear invisible, concentrate the transmission of energy into focused beams, or have chameleon-like abilities to reconfigure their absorption or transmission of different frequency ranges.

The innovation, described today in Nature Electronics, constructs the metamaterials using low-cost inkjet printing, making the method widely accessible and scalable while also providing benefits such as the ability to be applied to large conformable surfaces or interface with a biological environment. It is also the first demonstration that organic polymers can be used to electrically “tune” the properties of the metamaterials.

Electromagnetic metamaterials and meta-surfaces — their two-dimensional counterparts — are composite structures that interact with electromagnetic waves in peculiar ways. The materials are composed of tiny structures — smaller than the wavelengths of the energy they influence — carefully arranged in repeating patterns. The ordered structures display unique wave interaction capabilities that enable the design of unconventional mirrors, lenses and filters able to either block, enhance, reflect, transmit, or bend waves beyond the possibilities offered by conventional materials.

The Tufts engineers fabricated their metamaterials by using conducting polymers as a substrate, then inkjet printing specific patterns of electrodes to create microwave resonators. Resonators are important components used in communications devices that can help filter select frequencies of energy that are either absorbed or transmitted. The printed devices can be electrically tuned to adjust the range of frequencies that the modulators can filter.

Metamaterial devices operating in the microwave spectrum could have widespread applications to telecommunications, GPS, radar, and mobile devices, where metamaterials can significantly boost their signal sensitivity and transmission power. The metamaterials produced in the study could also be applied to medical device communications because the biocompatible nature of the thin film organic polymer could enable the incorporation of enzyme-coupled sensors, while its inherent flexibility could permit devices to be fashioned into conformable surfaces appropriate for use on or in the body.

“We demonstrated the ability to electrically tune the properties of meta-surfaces and meta-devices operating in the microwave region of the electromagnetic spectrum,” said Fiorenzo Omenetto, Frank C. Doble Professor of Engineering at Tufts University School of Engineering, director of the Tufts Silklab where the materials were created, and corresponding author of the study. “Our work represents a promising step compared to current meta-device technologies, which largely depend on complex and costly materials and fabrication processes.”

The tuning strategy developed by the research team relies entirely on thin-film materials that can be processed and deposited through mass-scalable techniques, such as printing and coating, on a variety of substrates. The ability to tune the electrical properties of the substrate polymers enabled the authors to operate the devices within a much wider range of microwave energies and up to higher frequencies (5 GHz) than was assumed to be possible with conventional non-meta materials (<0.1GHz).

Development of metamaterials for visible light, which has nanometer scale wavelength, is still in its early stages due to the technical challenges of making tiny arrays of substructures at that scale, but metamaterials for microwave energy, which has centimeter-scale wavelengths, are more amenable to the resolution of common fabrication methods. The authors suggest that the fabrication method they describe using inkjet printing and other forms of deposition on thin film conducting polymers could begin to test the limits of metamaterials operating at higher frequencies of the electromagnetic spectrum.

“This research is, potentially, only the beginning,” said Giorgio Bonacchini former post-doctoral fellow in Omenetto’s lab, now at Stanford University, and first author of the study. “Hopefully, our proof-of-concept device will encourage further explorations of how organic electronic materials and devices can be successfully used in reconfigurable metamaterials and meta-surfaces across the entire electromagnetic spectrum.”

Reference: “Reconfigurable microwave metadevices based on organic electrochemical transistors” by Giorgio E. Bonacchini and Fiorenzo G. Omenetto, 21 June 2021, Nature Electronics.
DOI: 10.1038/s41928-021-00590-0

High Capacity DNA Data Storage: Could All Your Digital Photos Be Stored As DNA?

MIT biological engineers have demonstrated a way to easily retrieve data files stored as DNA. This could be a step toward using DNA archives to store enormous quantities of photos, images, and other digital content. Credit: Image: MIT News. Small icons courtesy of the researchers

A technique for labeling and retrieving DNA data files from a large pool could help make DNA data storage feasible.

On Earth right now, there are about 10 trillion gigabytes of digital data, and every day, humans produce emails, photos, tweets, and other digital files that add up to another 2.5 million gigabytes of data. Much of this data is stored in enormous facilities known as exabyte data centers (an exabyte is 1 billion gigabytes), which can be the size of several football fields and cost around $1 billion to build and maintain.

Many scientists believe that an alternative solution lies in the molecule that contains our genetic information: DNA, which evolved to store massive quantities of information at very high density. A coffee mug full of DNA could theoretically store all of the world’s data, says Mark Bathe, an MIT professor of biological engineering.

“We need new solutions for storing these massive amounts of data that the world is accumulating, especially the archival data,” says Bathe, who is also an associate member of the Broad Institute of MIT and Harvard. “DNA is a thousandfold denser than even flash memory, and another property that’s interesting is that once you make the DNA polymer, it doesn’t consume any energy. You can write the DNA and then store it forever.”

A photo of the DNA “files.” Each silica sphere contains DNA sequences that encode a particular image, and the outside of the sphere is coated with nucleotide barcodes that describe the image contents. Credit: Courtesy of the researchers

Scientists have already demonstrated that they can encode images and pages of text as DNA. However, an easy way to pick out the desired file from a mixture of many pieces of DNA will also be needed. Bathe and his colleagues have now demonstrated one way to do that, by encapsulating each data file into a 6-micrometer particle of silica, which is labeled with short DNA sequences that reveal the contents.

Using this approach, the researchers demonstrated that they could accurately pull out individual images stored as DNA sequences from a set of 20 images. Given the number of possible labels that could be used, this approach could scale up to 10²⁰ files.

Bathe is the senior author of the study, which appears today in Nature Materials. The lead authors of the paper are MIT senior postdoc James Banal, former MIT research associate Tyson Shepherd, and MIT graduate student Joseph Berleant.

Stable storage

Digital storage systems encode text, photos, or any other kind of information as a series of 0s and 1s. This same information can be encoded in DNA using the four nucleotides that make up the genetic code: A, T, G, and C. For example, G and C could be used to represent 0 while A and T represent 1.

DNA has several other features that make it desirable as a storage medium: It is extremely stable, and it is fairly easy (but expensive) to synthesize and sequence. Also, because of its high density — each nucleotide, equivalent to up to two bits, is about 1 cubic nanometer — an exabyte of data stored as DNA could fit in the palm of your hand.

The researchers stored images like these, pictured, in DNA. Credit: Courtesy of the researchers

One obstacle to this kind of data storage is the cost of synthesizing such large amounts of DNA. Currently it would cost $1 trillion to write one petabyte of data (1 million gigabytes). To become competitive with magnetic tape, which is often used to store archival data, Bathe estimates that the cost of DNA synthesis would need to drop by about six orders of magnitude. Bathe says he anticipates that will happen within a decade or two, similar to how the cost of storing information on flash drives has dropped dramatically over the past couple of decades.

Aside from the cost, the other major bottleneck in using DNA to store data is the difficulty in picking out the file you want from all the others.

“Assuming that the technologies for writing DNA get to a point where it’s cost-effective to write an exabyte or zettabyte of data in DNA, then what? You’re going to have a pile of DNA, which is a gazillion files, images or movies and other stuff, and you need to find the one picture or movie you’re looking for,” Bathe says. “It’s like trying to find a needle in a haystack.”

Currently, DNA files are conventionally retrieved using PCR (polymerase chain reaction). Each DNA data file includes a sequence that binds to a particular PCR primer. To pull out a specific file, that primer is added to the sample to find and amplify the desired sequence. However, one drawback to this approach is that there can be crosstalk between the primer and off-target DNA sequences, leading unwanted files to be pulled out. Also, the PCR retrieval process requires enzymes and ends up consuming most of the DNA that was in the pool.

“You’re kind of burning the haystack to find the needle, because all the other DNA is not getting amplified and you’re basically throwing it away,” Bathe says.

File retrieval

As an alternative approach, the MIT team developed a new retrieval technique that involves encapsulating each DNA file into a small silica particle. Each capsule is labeled with single-stranded DNA “barcodes” that correspond to the contents of the file. To demonstrate this approach in a cost-effective manner, the researchers encoded 20 different images into pieces of DNA about 3,000 nucleotides long, which is equivalent to about 100 bytes. (They also showed that the capsules could fit DNA files up to a gigabyte in size.)

Each file was labeled with barcodes corresponding to labels such as “cat” or “airplane.” When the researchers want to pull out a specific image, they remove a sample of the DNA and add primers that correspond to the labels they’re looking for — for example, “cat,” “orange,” and “wild” for an image of a tiger, or “cat,” “orange,” and “domestic” for a housecat.

The primers are labeled with fluorescent or magnetic particles, making it easy to pull out and identify any matches from the sample. This allows the desired file to be removed while leaving the rest of the DNA intact to be put back into storage. Their retrieval process allows Boolean logic statements such as “president AND 18^th century” to generate George Washington as a result, similar to what is retrieved with a Google image search.

“At the current state of our proof-of-concept, we’re at the 1 kilobyte per second search rate. Our file system’s search rate is determined by the data size per capsule, which is currently limited by the prohibitive cost to write even 100 megabytes worth of data on DNA, and the number of sorters we can use in parallel. If DNA synthesis becomes cheap enough, we would be able to maximize the data size we can store per file with our approach,” Banal says.

For their barcodes, the researchers used single-stranded DNA sequences from a library of 100,000 sequences, each about 25 nucleotides long, developed by Stephen Elledge, a professor of genetics and medicine at Harvard Medical School. If you put two of these labels on each file, you can uniquely label 10¹⁰ (10 billion) different files, and with four labels on each, you can uniquely label 10²⁰ files.

George Church, a professor of genetics at Harvard Medical School, describes the technique as “a giant leap for knowledge management and search tech.”

“The rapid progress in writing, copying, reading, and low-energy archival data storage in DNA form has left poorly explored opportunities for precise retrieval of data files from huge (10²¹ byte, zetta-scale) databases,” says Church, who was not involved in the study. “The new study spectacularly addresses this using a completely independent outer layer of DNA and leveraging different properties of DNA (hybridization rather than sequencing), and moreover, using existing instruments and chemistries.”

Bathe envisions that this kind of DNA encapsulation could be useful for storing “cold” data, that is, data that is kept in an archive and not accessed very often. His lab is spinning out a startup, Cache DNA, that is now developing technology for long-term storage of DNA, both for DNA data storage in the long-term, and clinical and other preexisting DNA samples in the near-term.

“While it may be a while before DNA is viable as a data storage medium, there already exists a pressing need today for low-cost, massive storage solutions for preexisting DNA and RNA samples from Covid-19 testing, human genomic sequencing, and other areas of genomics,” Bathe says.

Reference: “Random access DNA memory using Boolean search in an archival file storage system” by James L. Banal, Tyson R. Shepherd, Joseph Berleant, Hellen Huang, Miguel Reyes, Cheri M. Ackerman, Paul C. Blainey and Mark Bathe, 10 June 2021, Nature Materials.
DOI: 10.1038/s41563-021-01021-3

The research was funded by the Office of Naval Research, the National Science Foundation, and the U.S. Army Research Office.

Toward Safer Breast Implants: How Implant Surfaces Affect Immune Response

Six-year effort includes researchers from Rice, MD Anderson, Baylor College of Medicine.

Rice University bioengineers collaborated on a six-year study that systematically analyzed how the surface architecture of breast implants influences the development of adverse effects, including an unusual type of lymphoma.

Every year, about 400,000 people receive silicone breast implants in the United States. According to FDA data, most of those implants need to be replaced within 10 years due to the buildup of scar tissue and other complications.

A team including researchers from the Massachusetts Institute of Technology (MIT), Rice, the University of Texas MD Anderson Cancer Center and Baylor College of Medicine published its findings online today in Nature Biomedical Engineering.

“The surface topography of an implant can drastically affect how the immune response perceives it, and this has important ramifications for the [implants’] design,” said Omid Veiseh, an assistant professor of bioengineering at Rice who began the research six years ago during a postdoctoral fellowship at MIT. “We hope this paper provides a foundation for plastic surgeons to evaluate and better understand how implant choice can affect the patient experience.”

The findings, were co-authored by two dozen researchers, including co-lead authors Veiseh and Joshua Doloff of Johns Hopkins University, MIT’s Robert Langer and two of Veiseh’s collaborators from the Texas Medical Center, Baylor’s Courtney Hodges and MD Anderson’s Mark Clemens.

Human impact

Veiseh, whose lab focuses on developing and studying biocompatible materials, said he is particularly excited about the discovery that surface architecture can be tuned to reduce host immune responses and fibrosis to breast implants.

“There’s a lot we still don’t understand about how the immune system orchestrates its response to implants, and it is really important to understand that within the context of biomaterials,” Veiseh said.

Veiseh continued the research after joining Rice’s faculty in 2017 as a CPRIT Scholar from the Cancer Prevention and Research Institute of Texas. He and two Ph.D. students from his lab, Amanda Nash and Samira Aghlara-Fotovat, collaborated on the project with the research groups of MD Anderson’s Clemens and Baylor’s Hodges to correlate findings from MIT animal studies with clinical data from human patients.

“Clinically, we have observed that patients exposed to textured-surface breast implants can develop breast implant-associated large cell lymphoma (BIA-ALCL), but this has not occurred with smooth-surface implants,” said Clemens, an associate professor of plastic surgery at MD Anderson who leads a multidisciplinary treatment team on the disease. “This paper gives important novel insights into cancer pathogenesis with clear implications for preventing disease before it develops.”

Veiseh said the work also provided important clues that will guide follow-up studies.

“That’s the most exciting part of this: it could lead to safer, more compatible biomaterials and implant designs,” Veiseh said.

Surface analysis

Silicone breast implants have been in use since the 1960s. The earliest versions had smooth surfaces, but patients with these implants often experienced a complication called capsular contracture, in which scar tissue formed around the implant and squeezed it, creating pain or discomfort as well as visible deformities. Implants could also flip after implantation, requiring surgical adjustment or removal.

In the late 1980s, some companies introduced rougher surfaces intended to reduce capsular contracture rates and make implants stay in place. The textured surfaces have peaks of varying heights. The peaks of some average hundreds of microns.

In 2019, the FDA requested breast implant manufacturer Allergan recall highly textured breast implants that had an average surface roughness of about 80 microns due to risk of BIA-ALCL, a cancer of the immune system.

In 2015, Veiseh and Doloff, then postdocs in the lab of MIT’s Langer, began testing five commercially available implants with different surface designs to see how they would interact with surrounding tissue and the immune system. These included the highly textured one that had been previously recalled, one that was completely smooth and three that were somewhere in between.

Experimental results

In a study of rabbits, the researchers found tissue exposed to the more heavily textured implant surfaces showed signs of increased activity from macrophages — immune cells that normally clear out foreign cells and debris.

All of the implants stimulated immune cells called T cells, but in different ways. The study found implants with rougher surfaces stimulated more pro-inflammatory T cell responses. Among the non-smooth implants, those with the smallest degree of roughness (4 microns) stimulated T cells that appeared to inhibit tissue inflammation.

The findings suggest that rougher implants rub against surrounding tissue and cause more irritation. This may explain why the rougher implants can lead to lymphoma: The hypothesis is that some of the texture sloughs off and gets trapped in nearby tissue, where it provokes chronic inflammation that can eventually lead to cancer.

The researchers also tested miniaturized versions of implants in mice. They manufactured these implants using the same techniques used to manufacture human-sized versions, and showed that more highly textured implants provoked more macrophage activity, more scar tissue formation and higher levels of inflammatory T cells. The researchers worked with the Hodges’ lab at Baylor to perform single-cell RNA sequencing of immune cells from these tissues to uncover the specific signals that made the immune cells more inflammatory.

“The surface properties of the implants have profoundly different effects on key signals between immune cells that help recognize and respond to foreign materials,” said Hodges, an assistant professor of molecular and cellular biology at Baylor. “The results show that the lightly textured surface avoided the strong negative cytokine immune response induced by the rough surface.”

Toward safer implants

After their animal studies, the researchers examined how human patients respond to different types of silicone breast implants by collaborating with MD Anderson on the analysis of tissue samples from BIA-ALCL patients.

They found evidence of the same types of immune responses observed in the animal studies. For example, they observed that tissue samples from patients that had been host to highly textured implants for many years showed signs of a chronic, long-term immune response. They also found that scar tissue was thicker in patients who had more highly textured implants.

“Doing across-the-board comparisons in mice, rabbits and then in human [tissue samples] really provides a much more robust and substantial body of evidence about how these compare to one another,” Veiseh said.

The authors said they hope their datasets will help other researchers optimize the design of silicone breast implants and other types of medical silicone implants for better safety.

“We are pleased that we were able to bring new materials science approaches to better understand issues of biocompatibility in the area of breast implants,” said Langer, the study’s senior author and MIT’s David H. Koch Institute Professor. “We also hope the studies that we conducted will be broadly useful in understanding how to design safer and more effective implants of any type.”

Reference: “The surface topography of silicone breast implants mediates the foreign body response in mice, rabbits and humans” by Joshua C. Doloff, Omid Veiseh, Roberto de Mezerville, Marcos Sforza, Tracy Ann Perry, Jennifer Haupt, Morgan Jamiel, Courtney Chambers, Amanda Nash, Samira Aghlara-Fotovat, Jessica L. Stelzel, Stuart J. Bauer, Sarah Y. Neshat, John Hancock, Natalia Araujo Romero, Yessica Elizondo Hidalgo, Isaac Mora Leiva, Alexandre Mendonça Munhoz, Ardeshir Bayat, Brian M. Kinney, H. Courtney Hodges, Roberto N. Miranda, Mark W. Clemens and Robert Langer, 21 June 2021, Nature Biomedical Engineering.
DOI: 10.1038/s41551-021-00739-4

Additional study co-authors include Jennifer Haupt and Morgan Jamiel of MIT; Jessica Stelzel, Stuart Bauer and Sara Neshat of Johns Hopkins; Roberto De Mezerville, Tracy Ann Perry, John Hancock, Natalia Araujo Romero, Yessica Elizondo and Isaac Mora Leiva of Establishment Labs; Courtney Chambers of Baylor; Roberto Miranda of MD Anderson; Marcos Sforza of Dolan Park Hospital in the United Kingdom; Alexandre Mendonca Munhoz of the University of São Paulo; Ardeshir Bayat of the University of Manchester; and Brian Kinney of the University of Southern California.

The research was funded by Establishment Labs. Langer, Hancock, Bayat, Kinney and Perry are members of the scientific advisory board of Establishment Labs and hold equity in the company. Sforza and Munhoz are members of the medical advisory board of Establishment Labs and hold equity in the company. Clemens is an investigator on the US IDE Clinical Trial for the Study of Safety and Effectiveness of Motiva Implants. De Mezerville, Romero, Elizondo and Leiva are employees of Establishment Labs and hold equity in the company. Doloff and Veiseh are paid Establishment Labs consultants.

NASA’s Webb Telescope Will Look Back in Time, Use Quasars to Unlock the Secrets of the Early Universe

This is an artist’s concept of a galaxy with a brilliant quasar at its center. A quasar is a very bright, distant and active supermassive black hole that is millions to billions of times the mass of the Sun. Among the brightest objects in the universe, a quasar’s light outshines that of all the stars in its host galaxy combined. Quasars feed on infalling matter and unleash torrents of winds and radiation, shaping the galaxies in which they reside. Using the unique capabilities of Webb, scientists will study six of the most distant and luminous quasars in the universe. Credit: NASA, ESA and J. Olmsted (STScI)

Quasars are very bright, distant and active supermassive black holes that are millions to billions of times the mass of the Sun. Typically located at the centers of galaxies, they feed on infalling matter and unleash fantastic torrents of radiation. Among the brightest objects in the universe, a quasar’s light outshines that of all the stars in its host galaxy combined, and its jets and winds shape the galaxy in which it resides.

Shortly after its launch later this year, a team of scientists will train NASA’s James Webb Space Telescope on six of the most distant and luminous quasars. They will study the properties of these quasars and their host galaxies, and how they are interconnected during the first stages of galaxy evolution in the very early universe. The team will also use the quasars to examine the gas in the space between galaxies, particularly during the period of cosmic reionization, which ended when the universe was very young. They will accomplish this using Webb’s extreme sensitivity to low levels of light and its superb angular resolution.

(Click image to see full infographic.) More than 13 billion years ago, during the Era of Reionization, the universe was a very different place. The gas between galaxies was largely opaque to energetic light, making it difficult to observe young galaxies. What allowed the universe to become completely ionized, or transparent, eventually leading to the “clear” conditions detected in much of the universe today? The James Webb Space Telescope will peer deep into space to gather more information about objects that existed during the Era of Reionization to help us understand this major transition in the history of the universe. Credit: NASA, ESA, and J. Kang (STScI)

Webb: Visiting the Young Universe

As Webb peers deep into the universe, it will actually look back in time. Light from these distant quasars began its journey to Webb when the universe was very young and took billions of years to arrive. We will see things as they were long ago, not as they are today.

“All these quasars we are studying existed very early, when the universe was less than 800 million years old, or less than 6 percent of its current age. So these observations give us the opportunity to study galaxy evolution and supermassive black hole formation and evolution at these very early times,” explained team member Santiago Arribas, a research professor at the Department of Astrophysics of the Center for Astrobiology in Madrid, Spain. Arribas is also a member of Webb’s Near-Infrared Spectrograph (NIRSpec) Instrument Science Team.

(Click image to see full infographic.) The universe is expanding, and that expansion stretches light traveling through space in a phenomenon known as cosmological redshift. The greater the redshift, the greater the distance the light has traveled. As a result, telescopes with infrared detectors are needed to see light from the first, most distant galaxies. Credit: NASA, ESA, AND L. Hustak (STSci)

The light from these very distant objects has been stretched by the expansion of space. This is known as cosmological redshift. The farther the light has to travel, the more it is redshifted. In fact, the visible light emitted at the early universe is stretched so dramatically that it is shifted out into the infrared when it arrives to us. With its suite of infrared-tuned instruments, Webb is uniquely suited to studying this kind of light.

Studying Quasars, Their Host Galaxies and Environments, and Their Powerful Outflows

The quasars the team will study are not only among the most distant in the universe, but also among the brightest. These quasars typically have the highest black hole masses, and they also have the highest accretion rates — the rates at which material falls into the black holes.

“We’re interested in observing the most luminous quasars because the very high amount of energy that they’re generating down at their cores should lead to the largest impact on the host galaxy by the mechanisms such as quasar outflow and heating,” said Chris Willott, a research scientist at the Herzberg Astronomy and Astrophysics Research Centre of the National Research Council of Canada (NRC) in Victoria, British Columbia. Willott is also the Canadian Space Agency’s Webb project scientist. “We want to observe these quasars at the moment when they’re having the largest impact on their host galaxies.”

An enormous amount of energy is liberated when matter is accreted by the supermassive black hole. This energy heats and pushes the surrounding gas outward, generating strong outflows that tear across interstellar space like a tsunami, wreaking havoc on the host galaxy.

Watch as the jets and winds from a supermassive black hole affect its host galaxy—and the space hundreds of thousands of light-years away over millions of years. Credit: NASA, ESA, and L. Hustak (STScI)

Outflows play an important role in galaxy evolution. Gas fuels the formation of stars, so when gas is removed due to outflows, the star-formation rate decreases. In some cases, outflows are so powerful and expel such large amounts of gas that they can completely halt star formation within the host galaxy. Scientists also think that outflows are the main mechanism by which gas, dust and elements are redistributed over large distances within the galaxy or can even be expelled into the space between galaxies – the intergalactic medium. This may provoke fundamental changes in the properties of both the host galaxy and the intergalactic medium.

Examining Properties of Intergalactic Space During the Era of Reionization

More than 13 billion years ago, when the universe was very young, the view was far from clear. Neutral gas between galaxies made the universe opaque to some types of light. Over hundreds of millions of years, the neutral gas in the intergalactic medium became charged or ionized, making it transparent to ultraviolet light. This period is called the Era of Reionization. But what led to the reionization that created the “clear” conditions detected in much of the universe today? Webb will peer deep into space to gather more information about this major transition in the history of the universe. The observations will help us understand the Era of Reionization, which is one of the key frontiers in astrophysics.

The team will use quasars as background light sources to study the gas between us and the quasar. That gas absorbs the quasar’s light at specific wavelengths. Through a technique called imaging spectroscopy, they will look for absorption lines in the intervening gas. The brighter the quasar is, the stronger those absorption line features will be in the spectrum. By determining whether the gas is neutral or ionized, scientists will learn how neutral the universe is and how much of this reionization process has occurred at that particular point in time.

The James Webb Space Telescope will use an innovative instrument called an integral field unit (IFU) to capture images and spectra at the same time. This video gives a basic overview of how the IFU works. Credit: NASA, ESA, CSA, and L. Hustak (STScI)

“If you want to study the universe, you need very bright background sources. A quasar is the perfect object in the distant universe, because it’s luminous enough that we can see it very well,” said team member Camilla Pacifici, who is affiliated with the Canadian Space Agency but works as an instrument scientist at the Space Telescope Science Institute in Baltimore. “We want to study the early universe because the universe evolves, and we want to know how it got started.”

The team will analyze the light coming from the quasars with NIRSpec to look for what astronomers call “metals,” which are elements heavier than hydrogen and helium. These elements were formed in the first stars and the first galaxies and expelled by outflows. The gas moves out of the galaxies it was originally in and into the intergalactic medium. The team plans to measure the generation of these first “metals,” as well as the way they’re being pushed out into the intergalactic medium by these early outflows.

The Power of Webb

Webb is an extremely sensitive telescope able to detect very low levels of light. This is important, because even though the quasars are intrinsically very bright, the ones this team is going to observe are among the most distant objects in the universe. In fact, they are so distant that the signals Webb will receive are very, very low. Only with Webb’s exquisite sensitivity can this science be accomplished. Webb also provides excellent angular resolution, making it possible to disentangle the light of the quasar from its host galaxy.

The quasar programs described here are Guaranteed Time Observations involving the spectroscopic capabilities of NIRSpec.

The James Webb Space Telescope will be the world’s premier space science observatory when it launches in 2021. Webb will solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.

Edible Cholera Vaccine – Made of Powdered Rice – Proves Safe in Phase 1 Human Trials

Researchers at the University of Tokyo have announced the successful results of the Phase 1 clinical trial of a new type of vaccine to protect against cholera and travelers’ diarrhea. The MucoRice-CTB vaccine is grown in rice plants and stimulates immunity through the mucosal membranes of the intestines. The vaccine can be stored and transported without refrigeration and does not need needles; it is simply mixed with liquid and drunk. Credit: Image by Dr. Hiroshi Kiyono, CC BY 4.0

Study points towards role of gut microbiome in vaccine effectiveness.

A new vaccine to protect against deadly cholera has been made by grinding up genetically modified grains of rice. The first human trial has shown no obvious side effects and a good immune response. Researchers based at the University of Tokyo and Chiba University have published the peer-reviewed results of the Phase 1 clinical trial of the vaccine, named MucoRice-CTB, in The Lancet Microbe.

Vaccine manufacturing has made enormous strides in 2020, spurred on by COVID-19. However, the complexity of mRNA-based SARS-CoV-2 vaccines has highlighted the value of inoculations that can be made, transported and stored cheaply and without refrigeration.

The MucoRice-CTB vaccine is stable at room temperature from start to finish.

“I’m very optimistic for the future of our MucoRice-CTB vaccine, especially because of the dose escalation results. Participants responded to the vaccine at the low, medium and high doses, with the largest immune response at the highest dose,” said Professor Hiroshi Kiyono, D.D.S., Ph.D., from the Institute of Medical Science at the University of Tokyo who leads the MucoRice project. Dr. Kiyono is also a faculty member at Chiba University in Japan and the University of California, San Diego, in the U.S.

Researchers at the University of Tokyo have announced the successful results of the Phase 1 clinical trial of a new type of vaccine to protect against cholera and travelers’ diarrhea. The cartoon shows a simplified summary of the MucoRice-CTB vaccine trial. Credit: Image by Dr. Hiroshi Kiyono, CC BY 4.0

Thirty volunteers received a placebo and groups of 10 volunteers received a total of four doses spaced every two weeks of either 3 milligrams (mg), 6 mg or 18 mg each of the vaccine. Tests two and four months after receiving the last dose revealed that volunteers who responded to the vaccine had IgA and IgG antibodies — two types of proteins the immune system produces to fight infections — specific to cholera toxin B (CTB). Participants who received a higher dose of vaccine were more likely to have CTB-specific antibodies.

An independent review board found no evidence of significant side effects.

Growing a new type of vaccine Vibrio cholerae bacteria is spread most often by drinking water contaminated with sewage. Without medical attention, cholera can kill in mere hours due to diarrhea with severe dehydration. Cholera infects 1.3 million to 4 million people and causes 21,000 to 143,000 deaths each year, according to the World Health Organization.

There are four modern needle-free cholera vaccines, all of which are given as drops on the tongue, but require cold storage and are made from whole killed or live-attenuated (weakened) cholera cells.

The new cholera vaccine grows in genetically modified Japanese short-grain rice plants that produce a nontoxic portion of CTB that can be recognized by the immune system. CTB is similar in structure to a toxin made by some types of disease-causing E. coli bacteria, so cholera vaccines often provide cross protection against travelers’ diarrhea.

Researchers grow the rice plants in a purpose-built, indoor hydroponic farm that meets WHO good manufacturing practice standards for medicines, which ensures that the vaccine remains uncontaminated and that the plants are isolated from the natural environment.

The plants produce the CTB subunit in their seeds, the edible grains of rice, and store the antigens in droplets called protein bodies with membranes made of fat.

“The rice protein bodies behave like a natural capsule to deliver the antigen to the gut immune system,” said Dr. Kiyono.

Other medicines have been grown in plants, most often in the leaves — including treatments for Ebola, lymphoma and flu — but the drugs have to be extracted and purified before being used. The grain-based aspect of the MucoRice system avoids those extra steps, the need for cold storage, and protects the antigens as they travel through the harsh acid of the stomach.

When the plants are mature, the rice is harvested and ground into a fine powder, then sealed in aluminum packets for storage. When people are ready to be vaccinated, the powder is mixed with about 90 milliliters (1/3 U.S. cup) of liquid and then drunk. Researchers have only tested the vaccine using saline (a salt solution equivalent to body fluids), but they expect it would work equally well with plain water.

Immunity through the gut is strong, but complicated by the microbiome

“The beautiful part of our vaccine is that it wisely uses the body’s mucosal immune system through the gut for the induction of antigen-specific antibodies,” said Dr. Kiyono.

MucoRice-CTB enters the body through intestinal mucosal membranes, mimicking a natural way of encountering and responding to germs. Stimulating the mucosal immune system produces two classes of antibodies that identify germs and target them for removal, IgG and IgA. Vaccines that are injected under the skin or into a muscle generally increase only IgG, not IgA, antibodies.

Volunteers who responded to MucoRice-CTB had their highest blood levels of antigen-specific IgG and IgA after eight to 16 weeks.

However, 11 of the 30 volunteers who received the vaccine showed low or no measurable immune response. All study volunteers reported never traveling outside of Japan, so it is unlikely that they had any previous exposure or natural immunity to V. cholerae or pathogenic E. coli.

“When we saw those data about the 11 low and nonresponders, we thought maybe gut microflora have an influence on the outcome of the immune response,” Dr. Kiyono recalled.

The microflora or microbiome is the community of microorganisms that live in our bodies and either benefit us or are harmless. It is well accepted that the microflora of the digestive system influence health and immunity, but scientists are just beginning to understand the precise mechanisms of the relationship.

Extensive genetic analysis of all volunteers’ fecal samples identified the thousands of bacterial species living in volunteers’ intestines.

“In simplified terms, high responders had more diversified microflora, and in the low-responder group, diversity was much narrower,” said Dr. Kiyono.

Researchers cautioned that the small size of the Phase 1 study — giving the vaccine to only 30 healthy Japanese male volunteers — means the relevance and prevalence of nonresponders is still unclear and that the total difference in microflora diversity was subtle. However, the results do hint at the larger role of microflora in vaccine effectiveness.

“It’s all speculation right now, but maybe higher microflora diversity creates a better situation for strong immune response against oral vaccine,” said Dr. Kiyono.

The link between the gut microbiome and vaccine effectiveness has been previously revealed by the unfortunate fact that most vaccines are developed in industrialized nations and some are then less effective when delivered in developing countries. Mucosal vaccines, including oral vaccines against polio and cholera, seem especially prone to this disparity. Most scientific theories to explain the phenomenon focus on chronic intestinal inflammation linked to poor sanitation. (https://doi.org/10.1186/1741-7007-8-129)

“Probably for every vaccination right now, even injected vaccines, we should think of the immune status of the individual based on the condition of their microflora,” said Dr. Kiyono.

It remains to be seen how microflora diversity will impact the global effectiveness of the new MucoRice edible vaccine system compared to other oral vaccines’ records.

For now, the researchers plan to work with partners in the pharmaceutical industry to bring MucoRice-CTB into the next phase of clinical trials in Japan and overseas.

Reference: “Assessment of Oral MucoRice-CTB vaccine for the safety and microbiota-dependent immunogenicity in humans: A Randomized Trial” by Yoshikazu Yuki, Masanori Nojima, Osamu Hosono, Hirotoshi Tanaka, Yasumasa Kimura, Takeshi Satoh, Seiya Imoto, Satoshi Uematsu, Shiho Kurokawa, Koji Kashima, Mio Mejima, Rika Nakahashi-Ouchida, Yohei Uchida, Takanori Marui, Noritada Yoshikawa, Fumitaka Nagamura, Kohtaro Fujihashi and Hiroshi Kiyono, 24 June 2021, The Lancet Microbe.

Blistering Stars in the Universe: Rare Insights Into How Violent Supernova Explosions Affect Nearby Stars

Artist’s impression of a supernova. Credit: James Josephides, Swinburne University of Technology

What happens if a supernova explosion goes off right beside another star? The star swells up, which scientists predict as a frequent occurrence in the Universe. Supernova explosions are the dramatic deaths of massive stars that are about 8 times heavier than our Sun.
 
Most of these massive stars are found in binary systems, where two stars closely orbit each other, so many supernovae occur in binaries. The presence of a companion star can also greatly influence how stars evolve and explode. For this reason, astronomers have long been searching for companion stars after supernovae — a handful have been discovered over the past few decades and some were found to have unusually low temperatures.

When a star explodes in a binary system, the debris from the explosion violently strikes the companion star. Usually, there’s not enough energy to damage the whole star, but it heats up the star’s surface instead. The heat then causes the star to swell up, like having a huge burn blister on your skin. This star blister can be 10 to 100 times larger than the star itself.
 
The swollen star appears very bright and cool, which might explain why some discovered companion stars had low temperatures. Its inflated state only lasts for an ‘astronomically’ short while — after a few years or decades, the blister can “heal” and the star shrinks back to its original form.
​
In their recently published study by a team of scientists led by OzGrav postdoctoral researcher Dr. Ryosuke Hirai (Monash University), the team carried out hundreds of computer simulations to investigate how companion stars inflate, or swell up, depending on their interaction with a nearby supernova. It was found that the luminosity of inflated stars is only correlated to their mass and doesn’t depend on the strength of the interaction with supernova. The duration of the swelling is also longer when the two stars are closer in distance.

“We applied our results to a supernova called SN2006jc, which has a companion star with a low-temperature. If this is in fact an inflated star as we believe, we expect it should rapidly shrink in the next few years,” explains Hirai

The number of companion stars detected after supernovae are steadily growing over the years. If scientists can observe an inflated companion star and its contraction, these data correlations can measure the properties of the binary system before the explosion — these insights are extremely rare and important for understanding how massive stars evolve.
 
“We think it’s important to not only find companion stars after supernovae, but to monitor them for a few years to decades to see if it shrinks back,” says Hirai.

Reference: “Observability of inflated companion stars after supernovae in massive binaries” by Misa Ogata, Ryosuke Hirai and Kotaro Hijikawa, 21 May 2021, Monthly Notices of the Royal Astronomical Society.
DOI: 10.1093/mnras/stab1439

Science Made Simple: What Are Quantum Networks?

Stakeholders from government, national laboratories, universities, and industry came together at DOE’s Quantum Internet Blueprint Workshop to identify research objectives and milestones to speed development of our nation’s quantum internet. Credit: Image courtesy of the Department of Energy’s Office of Science

Today’s internet connects us globally. It sends packets of information that carry our communications in classical signals – sent by bursts of light through optical fibers, electrically through copper wire, or by microwaves to make wireless connections. It is fast and reliable. So why develop a quantum internet that uses single photons – the smallest possible quantum of light – to carry information instead?

Because there are new scientific domains to explore. Quantum physics governs the domain of the very small. It allows us to understand – and use to our advantage – uniquely quantum phenomena for which there is no classical counterpart. We can use the principles of quantum physics to design sensors that make more precise measurements, computers that simulate more complex physical processes, and communication networks that securely interconnect these devices and create new opportunities for scientific discovery.

Quantum networks use the quantum properties of photons to encode information. For instance, photons polarized in one direction (for example, in the direction that would allow them to pass through polarized sunglasses) are associated with the value; one, photons polarized in the opposite direction (so they don’t pass through the sunglasses) are associated with the value zero. Researchers are developing quantum communication protocols to formalize these associations, allowing the quantum state of photons to carry information from sender to receiver through a quantum network.

Quantum networks use uniquely quantum phenomena, like superposition, no-cloning, and entanglement that are not available to classical networks. Before the photon is measured, it exists in a superposition of all its possible quantum states, each with a corresponding probability. Measurement selects one among these states. In fact, the photon’s quantum state cannot be measured without causing a disturbance that betrays the attempt. Nor can an arbitrary, unknown quantum state be copied – no cloning allowed. A properly designed and operated quantum network derives inherent security from this behavior.

But if the photon cannot be copied, how can the communication be amplified to reach distant recipients? This is where the quantum phenomenon of entanglement enters the picture. The quantum state of each entangled photon is correlated with that of its entangled partners, regardless of their distance apart. Quantum network repeaters are being developed that use entanglement to extend the range of quantum networks.

Will the emerging quantum internet make today’s classical internet obsolete? Not at all. The strengths of quantum networks are complementary to those of classical networks. We will reap the greatest benefit in the long run by incorporating both classical and quantum networks in an internet with capabilities that exceed what is possible with either technology on its own.

DOE Office of Science: Contributions to Quantum Networks

The DOE Office of Science delivers scientific discoveries and major scientific tools that will transform our understanding of nature and advance the energy, economic, and national security of the United States. At the DOE Quantum Internet Blueprint Workshop, participants set as a priority research objective the accelerated development of the building blocks of the quantum internet, including quantum network repeaters that use entanglement. Other research priorities seek to integrate these building blocks to create a reliable multi-hop network that controls the route of flying qubits and corrects for errors.

Dark Matter “Counterweight” Is Slowing the Spin of the Milky Way’s Galactic Bar

Artist’s conception of the Milky Way galaxy. Credit: Pablo Carlos Budassi

The spin of the Milky Way’s galactic bar, which is made up of billions of clustered stars, has slowed by about a quarter since its formation, according to a new study by researchers at University College London and the University of Oxford.

For 30 years, astrophysicists have predicted such a slowdown, but this is the first time it has been measured.

The researchers say it gives a new type of insight into the nature of dark matter, which acts like a counterweight slowing the spin.

In the study, published in the Monthly Notices of the Royal Astronomical Society, researchers analyzed Gaia space telescope observations of a large group of stars, the Hercules stream, which are in resonance with the bar – that is, they revolve around the galaxy at the same rate as the bar’s spin.

These stars are gravitationally trapped by the spinning bar. The same phenomenon occurs with Jupiter’s Trojan and Greek asteroids, which orbit Jupiter’s Lagrange points (ahead and behind Jupiter). If the bar’s spin slows down, these stars would be expected to move further out in the galaxy, keeping their orbital period matched to that of the bar’s spin.

The researchers found that the stars in the stream carry a chemical fingerprint – they are richer in heavier elements (called metals in astronomy), proving that they have traveled away from the galactic center, where stars and star-forming gas are about 10 times as rich in metals compared to the outer galaxy.

Using this data, the team inferred that the bar – made up of billions of stars and trillions of solar masses – had slowed down its spin by at least 24% since it first formed.

Co-author Dr. Ralph Schoenrich (UCL Mullard Space Science Laboratory) said: “Astrophysicists have long suspected that the spinning bar at the center of our galaxy is slowing down, but we have found the first evidence of this happening.

“The counterweight slowing this spin must be dark matter. Until now, we have only been able to infer dark matter by mapping the gravitational potential of galaxies and subtracting the contribution from visible matter.

“Our research provides a new type of measurement of dark matter – not of its gravitational energy, but of its inertial mass (the dynamical response), which slows the bar’s spin.”

Co-author and PhD student Rimpei Chiba, of the University of Oxford, said: “Our finding offers a fascinating perspective for constraining the nature of dark matter, as different models will change this inertial pull on the galactic bar.

“Our finding also poses a major problem for alternative gravity theories – as they lack dark matter in the halo, they predict no, or significantly too little slowing of the bar.”

The Milky Way, like other galaxies, is thought to be embedded in a ‘halo’ of dark matter that extends well beyond its visible edge.

Dark matter is invisible and its nature is unknown, but its existence is inferred from galaxies behaving as if they were shrouded in significantly more mass than we can see. There is thought to be about five times as much dark matter in the Universe as ordinary, visible matter.

Alternative gravity theories such as modified Newtonian dynamics reject the idea of dark matter, instead seeking to explain discrepancies by tweaking Einstein’s theory of general relativity.

The Milky Way is a barred spiral galaxy, with a thick bar of stars in the middle and spiral arms extending through the disc outside the bar. The bar rotates in the same direction as the galaxy.

Reference: “Tree-ring structure of Galactic bar resonance” by Rimpei Chiba and Ralph Schönrich, 19 April 2021, Monthly Notices of the Royal Astronomical Society.
DOI: 10.1093/mnras/stab1094

The research received support from the Royal Society, the Takenaka Scholarship Foundation, and the DiRAC supercomputing facility of the Science and Technology Facilities Council (STFC).

Engineers Develop a New Water Treatment Technology That Could Also Help Mars Explorers

A catalyst that destroys perchlorate in water could clean Martian soil.

A team led by University of California Riverside engineers has developed a catalyst to remove a dangerous chemical from water on Earth that could also make Martian soil safer for agriculture and help produce oxygen for human Mars explorers.

Perchlorate, a negative ion consisting of one chlorine atom bonded to four oxygen atoms, occurs naturally in some soils on Earth, and is especially abundant in Martian soil. As a powerful oxidizer, perchlorate is also manufactured and used in solid rocket fuel, fireworks, munitions, airbag initiators for vehicles, matches and signal flares. It is a byproduct in some disinfectants and herbicides. 

Because of its ubiquity in both soil and industrial goods, perchlorate is a common water contaminant that causes certain thyroid disorders. Perchlorate bioaccumulates in plant tissues and a large amount of perchlorate found in Martian soil could make food grown there unsafe to eat, limiting the potential for human settlements on Mars. Perchlorate in Martian dust could also be hazardous to explorers. Current methods of removing perchlorate from water require either harsh conditions or a multistep enzymatic process to lower the oxidation state of the chlorine element into the harmless chloride ion.

Doctoral student Changxu Ren and Jinyong Liu, an assistant professor of chemical and environmental engineering at UC Riverside’s Marlan and Rosemary Bourns College of Engineering, took inspiration from nature to reduce perchlorate in water at ambient pressure and temperature in one simple step.

Ren and Liu noted anaerobic microbes use molybdenum in their enzymes to reduce perchlorate and harvest energy in oxygen-starved environments.

“Previous efforts in constructing a chemical molybdenum catalyst for perchlorate reduction have not been successful,” Liu said. “Many other metal catalysts either require harsh conditions or are not compatible with water.”

The researchers tried to emulate the complicated microbial perchlorate reduction process with a simplified approach. They found by simply mixing a common fertilizer called sodium molybdate, a common organic ligand called bipyridine to bind the molybdenum, and a common hydrogen-activating catalyst called palladium on carbon, they produced a powerful catalyst that quickly and efficiently broke down the perchlorate in water using hydrogen gas at room temperature with no combustion involved.

“This catalyst is much more active than any other chemical catalyst reported to date and reduces more than 99.99% of the perchlorate into chloride regardless of the initial perchlorate concentration,” Ren said.

The new catalyst reduces perchlorate in a wide concentration range, from less than 1 milligram per liter to 10 grams per liter. This makes it suitable for use in various scenarios, including remediating contaminated groundwater, treating heavily contaminated wastewater from explosives manufacturing, and making Mars habitable.

“A convenient catalytic reduction system may help harvest oxygen gas from perchlorate washed from the Martian soil when the catalyst is coupled with other processes,” Liu said.

The paper, “A bioinspired molybdenum catalyst for aqueous perchlorate reduction,” was published in the Journal of the American Chemical Society. Ren and Liu were joined in the research by UC Riverside doctoral student Jinyu Gao, undergraduate student Jacob Palmer, and high school student Eric Y. Bi. Peng Yang and Mengqiang Zhu at the University of Wyoming characterized the catalyst with X-ray absorption spectroscopies and Ohio State University’s Jiaonan Sun and Yiying Wu performed the electrochemical testing. The research was funded by the National Science Foundation.

Reference: “A Bioinspired Molybdenum Catalyst for Aqueous Perchlorate Reduction” by Changxu Ren, Peng Yang, Jiaonan Sun, Eric Y. Bi, Jinyu Gao, Jacob Palmer, Mengqiang Zhu, Yiying Wu and Jinyong Liu, 18 May 2021, Journal of the American Chemical Society.
DOI: 10.1021/jacs.1c00595 

Reduced Risk of Cancer Among Heart Failure Patients That Use Statins

Statin use is linked to reduced risk of cancer among heart failure patients. Credit: European Heart Journal

Statin use among patients with heart failure is associated with a 16% lower risk of developing cancer compared with non-statin users during an average of four years of follow-up, according to new research published today (Wednesday, June 23, 2021) in the European Heart Journal.

In addition, the study found that statin use was associated with a 26% reduced risk of dying from cancer over the same period.

Previous research has shown that heart failure patients are at increased risk of developing cancer, possibly because heart failure may be a cancer-causing condition via shared pathways such as inflammation or genetic factors. However, there has been very little study of the associations between statin use and the risk of developing and dying from cancer in patients with heart failure. The current observational study of over 87,000 people in Hong Kong is the largest study to investigate this and the authors believe their findings can be extrapolated to other populations.

The study also found that the longer people with heart failure took statins, the greater the reduction in their risk of developing cancer. Compared with taking statins for between three months and two years and after adjusting for factors that could affect the results such as age, sex, smoking, alcohol consumption, and other health problems, if patients remained on statins for four and six years, their risk reduced by 18% and if they took them for six or more years the risk reduced by 22%.

Similarly, the risk of dying from cancer reduced by 33% and 39% if patients remained on statins for four to six years and for six or more years respectively, compared to patients who took them for between three months and two years.

Dr. Kai-Hang Yiu, from The University of Hong Kong, who led the study, said: “Ten years after starting statins, deaths from cancer were 3.8% among heart failure patients taking statins and 5.2% among non-users — a reduction in the absolute risk of death of 1.4%. The reduction in the absolute risk of developing cancer after six years on statins was 22% lower compared to those who received only between three months and two years of statins.”

In collaboration with Professor Carolyn Lam, from National Heart Center, Singapore, and other researchers, Dr. Yiu analyzed data from 87,102 patients in Hong Kong who were admitted to hospital with heart failure between 2003 and 2015. Patients were followed up until they were diagnosed with cancer, died or until the end of 2018, whichever came earlier. Patients were excluded from the study if they had a history of cancer or were diagnosed or died from it within 90 days of the first diagnosis of heart failure, if they had HIV, or if they had taken statins for fewer than 90 days. This left 36,176 statin users and 50,926 statin non-users for analysis.

A total of 3,863 (4.4%) of patients died from cancer during the follow-up and the commonest types of cancer were bowel, stomach, lung, liver and biliary (liver) system.

The researchers also found that deaths from any cause was lower among statin users compared to non-users: at ten years, 60.5% (21,886) statin users had died and 78.8% (40,130) non-statin users had died, meaning that statin use was associated with a 38% reduction in deaths from any cause compared to non-users.

The researchers say that advances in the treatment of heart failure, which saw a two-fold improvement in five-year survival rates from 29% to 60% between 1970 and 2009, have been offset by an increase in deaths from other causes, particularly cancer, among heart failure patients.

Dr. Yiu said: “Heart failure is a growing disease globally and deaths due to other causes unrelated to the heart and blood vessels are of concern. Our findings should raise doctors’ awareness of the increasing cancer incidence among heart failure patients and encourage them to pay extra attention to non-cardiovascular-related outcomes. Moreover, our study highlights the relationship between heart failure and cancer development, and provides important information regarding the possibility of reducing cancer incidence and related deaths by using statins in these patients.

“Randomized trials should be carried out to investigate this further. In addition, the findings, combined with previous research showing the strong association between heart failure and cancer, call for potential strategies to reduce the risk of cancer, such as screening for cancer in heart failure patients.”

Strengths of the study include its size, the use of data from a territory-wide, well-validated electronic healthcare database, and the adjustment for factors that could affect the results, including use of drugs such as metformin and aspirin that are known to protect against cancer.

Limitations include the fact that this is an observational non-randomized study which means it can only show an association between statins and lower cancer risk and not that the statins cause the reduction in risk; information on factors that could affect the risk of cancer, such as family history, was not available; there might be other factors that could affect the findings that were not included in the analyses; and there was no information on how well the heart’s left ventricle was performing and so it was not possible to evaluate the potential protective effects of statin use on left ventricular ejection fraction.

Reference: “Statin associated lower cancer risk and related mortality in patients with heart failure” by Qing-Wen Ren et al., 23 June 2021, European Heart Journal.
DOI: 10.1093/eurheartj/ehab325