Heavens

The aconitase superfamily currently contains four functional enzymes including the archetypical aconitase (referred to as "other aconitase enzymes"), and one hypothetical aconitase X (AcnX). The aconitase enzymes catalyze the homologous stereospecific isomerization, and their three-dimensional structures and catalytic mechanisms including the [4Fe-4S] iron-sulfur cluster are very similar each other (Fig. 1a). Therefore, the aconitase superfamily (enzymes) is a typical example that is suitable for the so-called "recruitment hypothesis of enzyme evolution"; the gene duplication of multi-specific enzymes, followed by the narrowing of substrate specificity (ref. 1).

AcnX (subfamily) is further classified into "AcnXType-I" consisting of a single polypeptide, and "AcnXType-II" consisting of (fragmented) small and large polypeptide chains. In 2016, we first revealed that AcnXType-I enzyme from bacteria functions as a cis-3-hydroxy-L-proline (C3LHyp) dehydratase (Fig. 1b) (ref. 2). Furthermore, in 2018, other researchers reported that AcnXType-II enzyme from archaea functions as a mevalonate 5-phosphate (MVA5P) dehydratase (ref. 3). To elucidate their catalytic mechanisms, we herein report for the first time the crystal structures of AcnXType-I from Agrobacterium tumefaciens, a plant pathogenic bacterium (AtAcnX), and AcnXType-II from Thermococcus kodakarensis, a hyperthermophilic archaeon (TkAcnX).

AtAcnX and TkAcnX commonly consisted of four domains (fragments), and their structural frameworks of each domain were similar to their counterparts of other aconitase enzymes (Fig. 2). TkAcnX had a cuboidal [3Fe-4S] cluster, which must be derived from the [4Fe-4S] cluster unit via the loss of one iron atom, similar to other aconitase enzymes (Fig. 3a, b). Surprisingly, AtAcnX had a planar [2Fe-2S] cluster (Fig. 3c, d). Most interesting question was whether AtAcnX and TkAcnX can recognize substrates without structural similarity. Collectively, the (superimposed) backbones of C3LHyp and MVA5P were recognized by homologous residues between AtAcnX and TkAcnX (Fig. 4a), whereas their specific structural moieties by different residues (Fig. 4b, c). Since the former residues are completely conserved in other aconitase enzymes, they must be "most ancestral" active sites for aconitase superfamily. Furthermore, the acyclic MVA5P is structurally similar to those of aconitase enzymes, whereas TkAcnX recognized the substrate through homologous manners to AtAcnX, suggesting that substrate specificities (and [4Fe-4S] clusters) for TkAcnX and other aconitase enzymes had acquired each other independently.

The common ancestor of aconitase superfamily (open circle in Fig. 5), appearing before the previously proposed one (closed circle), had a similar structural framework and a few residues as active site (described above), whereas there was no [Fe-S] cluster. These results provide novel insights into the evolutionary scenario of the aconitase superfamily based on the recruitment hypothesis, and requirement of complicated metabolic pathways in primordial cell.

The plates of the Earth's crust perform complicated movements that can be attributed to quite simple mechanisms. That is the short version of the explanation of a rift that began to tear the world apart over a length of several thousand kilometers 105 million years ago. The scientific explanation appears today in the journal Nature Geoscience.

According to the paper, a super volcano split the Earth's crust over a length of 7,500 kilometers, pushing the Indian Plate away from the African Plate. The cause was a "plume" in the Earth's mantle, i.e. a surge of hot material that wells upwards like an atomic mushroom cloud in super slow motion. It has long been known that the Indian landmass thus made its way northward and bumped into Eurasia. But a seemingly counterintuitive east-west movement of the continental plates was also part of the process. This is supported by calculations by a team led by Dutch scientist Douwe van Hinsbergen (Utrecht University) and Bernhard Steinberger (GFZ German Research Centre for Geosciences).

According to the findings, the Indian Plate did not simply move away from Africa, but rotated in the process. The reason for this is the subcontinent, whose land mass acts on the much larger continental plate like an axis around which the entire plate rotates. In the south, the scissors opened, in the north they closed - there, mountain-building processes and the subduction of crustal plates were induced.

This has dramatic effects up to the present time: The subduction processes continue and trigger earthquakes again and again in the Mediterranean region between Cyprus and Turkey. The traces of the plume and the supervolcano can still be identified today. They are flood basalts on Madagascar and in the southwest of India. They testify to immense volcanic activity fed by the mantle plume.

Bernhard Steinberger has calculated the movement and pressure that the super volcano near present-day Madagascar could cause further north on the Arabian Peninsula and in what is now the Mediterranean. He has also published a "kitchen table experiment" on Youtube, which illustrates the movements. Link: https://www.youtube.com/watch?v=1VzCzg2KRgg

An affordable lab system that uses grass blades to turn cells into cultured meat has been developed at the University of Bath in the UK.

Researchers have successfully taken grass from the university's campus and used it to create a scaffold that animal cells can attach to and grow on. The resulting tissue has the potential to be used both as lab-made meat and as human muscle tissue to repair or replace tissue which has been damaged or lost through injury or disease.

The study, by Dr Paul De Bank (Department of Pharmacy & Pharmacology), Professor Marianne Ellis (Department of Chemical Engineering) and Scott Allan (a PhD researcher in the Department of Chemical Engineering), is published in this month's Journal of Biomedical Materials Research - Part A.

The first step in the new bioengineering process involves emptying grass blades of their native cells in a process known as decellularisation. The decellularised blades are then seeded with a set of cells derived from a mouse cell line (these cells would eventually be replaced by bovine stem cells). The introduced cells stick to the scaffold's surface, multiply and form links with neighbouring cells, eventually growing as a cell mass to form new 3D tissue.

There are several challenges researchers must overcome when looking for a suitable scaffold on which to engineer new muscle tissue. First, the scaffold must be one cells can readily attach to the surface. It must then allow these cells to proliferate and align in a way that precisely mimics the fibres of the natural tissue they are replicating (with muscle fibres, for instance, all the cells need to contract and relax in tandem). Second, for scale-up, the scaffold must be cost-effective and straightforward to manufacture. For lab-grown meat, there is a third challenge: the scaffold must be edible to humans, even if not highly digestible (as is the case for grass).

The Bath project shows grass blades fulfil all criteria.

Dr Paul De Bank, who led the research, said: "When we were looking for a scaffold for our cells, we wanted to find something that was both sustainable and edible. I thought along the lines of a decellularised natural material because cellulose (which grass is largely made of) is edible, but also because grass has aligned grooves that I hoped would allow the cells to line up together to make the fibres we needed - and it worked!"

He added: "When we eat beef, we're partly eating the grass the cows have grazed on in their lifetime. What's neat about our study is that it shows that we can directly replace the animals with the grass they eat. Our system needs to be scaled up but I'm hopeful that sooner rather than later, we could have a meat product on the market based on grass."

The adhesion of the animal stem cells to the grass surface was found to be around 35%, which is considered a good result. "Often, decellularised plant scaffolds need to be chemically modified to get cells to grow on them. The great thing we've found with grass is that we get significant adhesion without further processing steps." said Dr De Bank, adding: "We are, however, hoping to find a way to increase this adhesion - we have a new PhD student who will be working on this, exploring ways to optimise cell attachment and growth.

The next big challenge will be scaling up this process to generate sufficient quantities of both cells and scaffold material in order to produce a significant quantity of muscle tissue. If this is successful then - one day - consumers may be able to buy grass-reared meat with a clear conscience, free from the environmental and animal-welfare concerns many are wrestling with today.

For the first time, scientists detected gravitational waves caused by mergers between black holes and neutron stars. Researchers from LIGO, Virgo, and KAGRA detected the two gravitational wave events--from distances of more than 900 million light-years away--within a span of 10 days in January 2020 during the second half of LIGO and Virgo's third observing run. Astrophysical Journal Letters published the results and their implications today: https://iopscience.iop.org/article/10.3847/2041-8213/ac082e.

Researchers from Rochester Institute of Technology's Center for Computational Relativity and Gravitation (CCRG) helped identify key characteristics about the merger events. Anjali Yelikar, an astrophysical sciences and technology Ph.D. student from India, was among those heavily involved in the findings. She used parameter estimation code developed by Associate Professor Richard O'Shaughnessy and alumnus Jacob Lange '18 MS (astrophysical sciences and technology), '20 Ph.D. (astrophysical sciences and technology) to find the mass, spin, distance from Earth, and position in the sky of the black holes and neutron stars involved.

"It's a real dream come true to be a part of a discovery like this," said Yelikar. "I was an undergraduate student when LIGO announced the first gravitational wave detection in 2016. It's amazing to see how far the science has come and I am excited to see what new developments await as the scientific community develops more sensitive detectors."

The yearlong third observing run was cut short by a month due to the coronavirus pandemic in March 2020 and the fourth is expected to begin in the summer of 2022, bringing more advanced detectors to the fold. Two main theories suggest how neutron stars and black holes could merge--one starting with two stars already orbiting each other and the other starting with unrelated supernova explosions--and while the mergers announced today offer hints about their origins, scientists hope to find more confirmation in subsequent observing runs.

"These elusive systems have long been missing from astronomers' family portrait of compact binaries," said O'Shaughnessy. "Now that we see the whole family, we can use this portrait to try to understand their relationships and lineage. For example, at least one of the neutron stars in these objects is relatively big, compared to neutron stars found before. That may be a clue into how cosmic explosions work and how these objects form."

Scientists did not observe electromagnetic wave counterparts to the gravitational waves caused by the events despite follow-up observations from multiple observatories. However, that is also something scientists will hunt for during future observing runs.

"This discovery is very exciting, not only because it confirms the existence of black-hole-neutron-star binaries, but also because such binaries are potential sources of extremely intense gamma-ray bursts," said Yosef Zlochower, an associate professor in the School of Mathematical Sciences who develops simulations used to compare against gravitational wave signals. "This leads to the real possibility of future combined gravitational-wave and electromagnetic observations of these sources."

Professor John Whelan, principal investigator of RIT's group in the LIGO Scientific Community, said, "With this observation of gravitational waves from yet another type of astrophysical system, the LIGO, Virgo and now KAGRA collaborations continue to broaden the field of gravitational wave astronomy. We look forward to further discoveries as we analyze data from this and future observing runs."

The invention of the laser has opened the era of nonlinear optics, which today plays an important role in many scientific, industrial and medical applications. These applications all benefit from the availability of compact lasers in the visible range of the electromagnetic spectrum. The situation is different at XUV wavelengths, where very large facilities (so called free-electron lasers) have been built to generate intense XUV pulses. One example of these is FLASH in Hamburg that extends over several hundred meters. Smaller intense XUV sources based on HHG have also been developed. However, these sources still have a footprint of tens of meters, and have so far only been demonstrated at a few universities and research institutes worldwide.

A team of researchers from the Max Born Institute (Berlin, Germany), ELI-ALPS (Szeged, Hungary) and INCDTIM (Cluj-Napoca, Romania) has recently developed a new scheme for the generation of intense XUV pulses. Their concept is based on HHG, which relies on focusing a near-infrared (NIR) laser pulse into a gas target. As a result, very short light bursts with frequencies that are harmonics of the NIR driving laser are emitted, which thereby are typically in the XUV region. To be able to obtain intense XUV pulses, it is important to generate as much XUV light as possible. This is typically achieved by generating a very large focus of the NIR driving laser, which requires a large laboratory.

Scientists from the Max Born Institute have demonstrated that it is possible to shrink an intense XUV laser by using a setup which extends over a length of only two meters. To be able to do so, they used the following trick: Instead of generating XUV light at the focus of the NIR driving laser, they placed a very dense jet of atoms relatively far away from the NIR laser focus, as shown in Fig. 1. This has two important advantages: (1) Since the NIR beam at the position of the jet is large, many XUV photons are generated. (2) The generated XUV beam is large and has a large divergence, and can therefore be focused to a small spot size. The large number of XUV photons in combination with the small XUV spot size makes it possible to generate intense XUV laser pulses. These results were confirmed by computer simulations that were carried out by a team of researchers from ELI-ALPS and INCDTIM.

To demonstrate that the generated XUV pulses are very intense, the scientists studied multi-photon ionization of argon atoms. They were able to multiply ionize these atoms, leading to ion charge states of Ar2+ and Ar3+. This requires the absorption of at least two and four XUV photons, respectively. In spite of the small footprint of this intense XUV source, the obtained XUV intensity of 2 x 1014 W/cm2 exceeds that of many already existing intense XUV sources.

The new concept can be implemented in many laboratories worldwide, and various areas of research may benefit. This includes attosecond-pump attosecond-probe spectroscopy, which has so far been extremely difficult to do. The new compact intense XUV laser could overcome the stability limitations that exist within this technique, and could be used to observe electron dynamics on extremely short timescales. Another area that is expected to benefit is the imaging of nanoscale objects such as bio-molecules. This could improve the possibilities for making movies in the nano-cosmos on femtosecond or even attosecond timescales.

While exploring two exoplanets in a bright nearby star system, ESA's exoplanet-hunting Cheops satellite has unexpectedly spotted the system's third known planet crossing the face of the star. This transit reveals exciting details about a rare planet "with no known equivalent", say the researchers.

The discovery is one of the first results from ESA's Cheops (CHaracterising ExOPlanet Satellite), and the first time an exoplanet with a period of over 100 days has been spotted transiting a star that is bright enough to be visible to the naked eye.

Named Nu2 Lupi, this bright, Sun-like star is located just under 50 light-years away from Earth in the constellation of Lupus (the Wolf). In 2019, the High Accuracy Radial velocity Planet Searcher (HARPS) at the ESO 3.6-metre telescope in Chile discovered three exoplanets (named 'b', 'c' and 'd', with the star deemed to be object 'A') in the system, with masses between those of Earth and Neptune and orbits lasting 11.6, 27.6 and 107.6 days. The innermost two of these planets - b and c - were subsequently found to transit Nu2 Lupi by NASA's Transiting Exoplanet Survey Satellite (TESS), making it one of only three naked-eye stars known to host multiple transiting planets.

"Transiting systems such as Nu2 Lupi are of paramount importance in our understanding of how planets form and evolve, as we can compare several planets around the same bright star in detail," says Laetitia Delrez of the University of Liège, Belgium, and lead author of the new finding.

"We set out to build on previous studies of Nu2 Lupi and observe planets b and c crossing the face of Nu2 Lupi with Cheops, but during a transit of planet c we spotted something amazing: an unexpected transit by planet 'd', which lies further out in the system."

Planetary transits create a valuable opportunity to study a planet's atmosphere, orbit, size and interior. A transiting planet blocks a tiny but detectable proportion of its star's light as it crosses in front of its star - and it was this drop in light that led Laetitia and colleagues to their discovery. As long-period exoplanets orbit so far from their stars, the chances of seeing one during a transit are incredibly low, making Cheops' finding a real surprise.

Using the high-precision capabilities of Cheops, planet d was found to be about 2.5 times the radius of Earth, confirmed to take just over 107 days to loop once around its star and, using archival observations from ground-based telescopes, found to have a mass of 8.8 times that of Earth.

"The amount of stellar radiation reaching planet d is also mild in comparison to many other discovered exoplanets; in our Solar System, Nu2 Lupi d would orbit between Mercury and Venus," adds co-author David Ehrenreich of the University of Geneva, Switzerland. "Combined with its bright parent star, long orbital period, and suitability for follow-up characterisation, this makes planet d hugely exciting - it is an exceptional object with no known equivalent, and sure to be a golden target for future study."

Most long-period transiting exoplanets discovered to date have been found around stars that are too faint to allow detailed follow-up observations, meaning that little is known about their planets' properties. Nu2 Lupi, however, is bright enough to be an attractive target for other powerful telescopes based in space -- such as the NASA/ESA Hubble Space Telescope or forthcoming NASA/ESA/CSA James Webb Space Telescope -- or large observatories on the ground.

"Given its overall properties and orbit, this makes planet d a uniquely favourable target for studying an exoplanet with a mild-temperature atmosphere around a star similar to the Sun," says Laetitia.

By combining new Cheops data with archival data from other observatories, the researchers were able to accurately determine the mean densities of all of Nu2 Lupi's known planets, and put strong constraints on their possible compositions.

They found planet b to be mainly rocky, while planets c and d appear to contain large amounts of water enshrouded in envelopes of hydrogen and helium gases. In fact, planets c and d contain far more water than Earth: a quarter of each planet's mass is made up of water, compared to less than 0.1% for Earth. This water, however, is not liquid, instead taking the form of high-pressure ice or high-temperature steam.

"While none of these planets would be habitable, their diversity makes the system even more exciting, and a great future prospect for testing how these bodies form and change over time," says ESA Cheops project scientist Kate Isaak. "There is also the potential to search for rings or moons in the Nu2 Lupi system, as the exquisite precision and stability of Cheops could allow detection of bodies down to roughly the size of Mars. "

Cheops is designed to collect ultra-high precision data of individual stars known to host planets, rather than sweeping more generally for possible exoplanets around many stars - and this focus and precision is proving exceptionally useful in understanding the star systems around us.

"These exciting results demonstrate once again the huge potential of Cheops," adds Kate. "Cheops will allow us not just to better understand known exoplanets, as shown in this and other early results from the mission, but also to discover new ones and reveal their secrets."

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."

HOUSTON - (June 23, 2021) - Bone cancer is hard to treat and prone to metastasis. Research teams at Rice University and Baylor College of Medicine have a new strategy to attack it.

Chemist Han Xiao at Rice and biologist Xiang Zhang at Baylor and their labs have developed an antibody conjugate called BonTarg that delivers drugs to bone tumors and inhibits metastasis.

Their open-access study, which appears in Science Advances, shows how Xiao's pClick technology can be used to link bone-targeting antibodies and therapeutic molecules.

In experiments, they used pClick to couple a molecule used to treat osteoporosis, alendronate, with the HER2-targeting antibody trastuzumab used to treat breast cancer and found it significantly enhanced the concentration of the antibody at tumor sites.

They reported the combination also inhibited secondary metastasis from infected organs seeded by bone tumors.

"Bone cancer is really challenging to treat, and clinical trials of different treatments have been disappointing for people with bone metastasis," said Xiao, who joined Rice in 2017 with funding from the Cancer Prevention and Research Institute of Texas (CPRIT). "We feel our strategy is a real game changer."

"Getting effective concentrations of drugs to bone tumors has been challenging because bones are hard, their networks of blood vessels is limited and drugs have tended to attach to adjacent healthy tissues," Zhang said.

The new strategy employs bisphosphonates, a class of drugs typically used to treat osteoporosis. Bisphosphonates have a high binding affinity for hydroxyapatite, the main component of hard bone, and help overcome physical and biological barriers in the bone microenvironment.

They're also amenable to binding with drugs through pClick, which uses a cross-linker to snap to specific sites on antibodies without having to re-engineer them with harmful chemicals, enzymes or ultraviolet light.

The result is a molecule that seeks out bone tumors and stays put, giving the drug time to kill tumor cells. It helps that bisphosphonate molecules prefer acidic sites like bone tumors, keeping the drug concentration higher there than in surrounding healthy tissue.

The researchers chose breast cancer drugs because while many recover from the disease, 20 to 40% of breast cancer survivors eventually suffer metastases to distant organs, with metastasis to bone occurring in about 70% of these cases, significantly increasing mortality, they said.

While chemotherapy, hormone and radiation therapy used to treat women with bone metastatic breast cancers can shrink or slow bone metastasis, they usually do not eliminate the metastases, Xiao said.

"Bone is kind of a fertile soil for cancer cell," Xiao said. "If a cancer cell reaches it, then it has a really good chance to grow and to further migrate, for example to the brain, the heart, the liver or to other tissues. That's a really bad situation for a patient."

Xiao hopes to get the compound into a clinical trial, and sees potential for custom conjugates that treat other tumors prone to metastasis, including prostate cancer.

Postdoctoral researchers Zeru Tian of Rice and Ling Wu of Baylor are co-lead authors of the paper. Co-authors are graduate students Chenfei Yu, Yuda Chen, Axel Loredo and Kuan-Lin Wu and postdoctoral researcher Lushun Wang of Rice; and postdoctoral fellows Zhan Xu, Igor Bado and Weijie Zhang and instructor Hai Wang of Baylor.

Xiao is the Norman Hackerman-Welch Young Investigator, the Cancer Prevention and Research Institute of Texas (CPRIT) Scholar in Cancer Research and an assistant professor of chemistry, bioengineering and biosciences. Zhang is the William T. Butler, M.D., Endowed Chair for Distinguished Faculty, McNair Scholar, associate director of the Lester and Sue Smith Breast Center, professor of molecular and cellular biology and member of the Dan L Duncan Comprehensive Cancer Center.

The research was supported by CPRIT, the National Institutes of Health, the Robert A. Welch Foundation, the U.S. Department of Defense, the John S. Dunn Foundation, the Hamill Foundation, the Breast Cancer Research Foundation and the McNair Medical Institute.

All plant cells obtain their energy mainly from two organelles they contain - chloroplasts (responsible for photosynthesis) and mitochondria (responsible for the biochemical cycle of respiration that converts sugars into energy). However, a large number of a plant cell's genes in its mitochondria and chloroplasts can develop defects, jeopardising their function. Nevertheless, plant cells evolved an amazing tool called the RNA editosome (a large protein complex) to repair these kinds of errors. It can modify defective messenger RNA that result from defective DNA by transforming (deamination) of certain mRNA nucleotides.

Automatic error correction in plant cells

Automatic error correction in plants was discovered about 30 years ago by a team headed by plant physiologist Axel Brennicke and two other groups simultaneously. This mechanism converts certain cytidine nucleotides in the messenger RNA into uridine in order to correct errors in the chloroplast DNA or mitochondrial DNA. RNA editing is therefore essential to processes such as photosynthesis and cellular respiration in plants. Years later, further studies showed that a group of proteins referred to as PPR proteins with DYW domains play a central role in plant RNA editing. These PPR proteins with DYW domains are transcribed in the cell nucleus and migrate through the cells to chloroplasts and mitochondria. However, they are inactive on their way to these organelles. Only once they are within the organelles do they become active and execute their function at a specific mRNA site. How this activation works, however, has been a mystery until now.

It doesn't work in a test tube

For many years, it was not possible to synthetically produce these DYW-type PPR proteins in the laboratory to study their function and structure more closely. Only now has a German-Japanese team headed by structural biologist and biochemist Dr. Gert Weber from the Joint Protein Crystallography Group at Helmholtz-Zentrum Berlin and Freie Universität Berlin succeeded in doing so.

Now: 3D structure of the key protein decoded

Prof. Mizuki Takenaka's group had previously been able to produce the DYW domain in bacteria. Takenaka has been conducting research at Kyoto University since 2018 and previously worked in Axel Brennicke's laboratory in Ulm, Germany. Tatiana Barthel (University of Greifswald and now at HZB) was then able to grow the first protein crystals of the DYW domain. A large number of these delicate crystals have now been analysed at the MX beamlines of BESSY II so that the three-dimensional architecture of the DYW domain could be decoded. "Thanks to the Joint Research Group co-located at HZB and FU Berlin, we have the capability of beam time for measurements very quickly when needed, which was crucial", says Dr. Manfred Weiss, who is responsible for the MX beamlines at BESSY II and co-author of the study.

Mechanism of activation discovered

This three-dimensional architecture has actually provided the crucial clue to the mechanism of DYW domain activation that applies to all plants. It is due to a zinc atom located in the centre of the DYW domain that can accelerate the deamination of cytidine to uridine like a catalyst. For this to happen, however, the zinc must be optimally positioned. The activation switch is provided by a very unusual gating domain in the immediate vicinity of the catalytic centre - the structural analysis shows that this gating domain can assume two different positions, thereby switching the enzyme on or off. "The movement of the gating domain regulates the extent to which the zinc ion is available for the catalytic reaction", Weber explains.

A molecule like scissors

Now it has become clear why getting DYW-type PPR proteins to react with RNA in the test tube has been difficult until now: these PPR proteins are nominally inactive and require activation. In the plant cells, they are first produced in the cell nucleus and then very likely migrate in an inactivated state to the organelles, where they become activated. "This is ideal, because otherwise these molecules would be active along the way, altering various RNA molecules in an uncontrolled fashion harmful to the cell", says Weber.

Universal repair tool

This work is a breakthrough for plant molecular biology because it describes an additional level of sophisticated regulation in chloroplasts and mitochondria. The results are fundamental for plant science, but they could also play a role in our daily lives someday. The DYW domain might provide a useful tool for controllable and site-specific C-to-U and U-to-C RNA editing. This could open up new bioengineering and medical applications, such as reprogramming certain mitochondrial genes without changing a cell's nuclear DNA.

A research team led by the University of Arizona has reconstructed in unprecedented detail the history of a dust grain that formed during the birth of the solar system more than 4.5 billion years ago. The findings provide insights into the fundamental processes underlying the formation of planetary systems, many of which are still shrouded in mystery.

For the study, the team developed a new type of framework, which combines quantum mechanics and thermodynamics, to simulate the conditions to which the grain was exposed during its formation, when the solar system was a swirling disk of gas and dust known as a protoplanetary disk or solar nebula. Comparing the predictions from the model to an extremely detailed analysis of the sample's chemical makeup and crystal structure, along with a model of how matter was transported in the solar nebula, revealed clues about the grain's journey and the environmental conditions that shaped it along the way.

The grain analyzed in the study is one of several inclusions, known as calcium-aluminum rich inclusions, or CAIs, discovered in a sample from the Allende meteorite, which fell over the Mexican state of Chihuahua in 1969. CAIs are of special interest because they are thought to be among the first solids that formed in the solar system more than 4.5 billion years ago.

Similar to how stamps in a passport tell a story about a traveler's journey and stops along the way, the samples' micro- and atomic-scale structures unlock a record of their formation histories, which were controlled by the collective environments to which they were exposed.

"As far as we know, our paper is the first to tell an origin story that offers clues about the likely processes that happened at the scale of astronomical distances with what we see in our sample at the scale of atomic distances," said Tom Zega, a professor in the University of Arizona's Lunar and Planetary Laboratory and the first author of the paper, published in The Planetary Science Journal.

Zega and his team analyzed the composition of the inclusions embedded in the meteorite using cutting-edge atomic-resolution scanning transmission electron microscopes - one at UArizona's Kuiper Materials Imaging and Characterization Facility, and its sister microscope located at the Hitachi factory in Hitachinaka, Japan.

The inclusions were found to consist mainly of types of minerals known as spinel and perovskite, which also occur in rocks on Earth and are being studied as candidate materials for applications such as microelectronics and photovoltaics.

Similar kinds of solids occur in other types of meteorites known as carbonaceous chondrites, which are particularly interesting to planetary scientists as they are known to be leftovers from the formation of the solar system and contain organic molecules, including those that may have provided the raw materials for life.

Precisely analyzing the spatial arrangement of atoms allowed the team to study the makeup of the underlying crystal structures in great detail. To the team's surprise, some of the results were at odds with current theories on the physical processes thought to be active inside protoplanetary disks, prompting them to dig deeper.

"Our challenge is that we don't know what chemical pathways led to the origins of these inclusions," Zega said. "Nature is our lab beaker, and that experiment took place billions of years before we existed, in a completely alien environment."

Zega said the team set out to "reverse-engineer" the makeup of the extraterrestrial samples by designing new models that simulated complex chemical processes, which the samples would be subjected to inside a protoplanetary disk.

"Such models require an intimate convergence of expertise spanning the fields of planetary science, materials science, mineral science and microscopy, which was what we set out to do," added Krishna Muralidharan, a study co-author and an associate professor in the UArizona's Department of Materials Science and Engineering.

Based on the data the authors were able to tease from their samples, they concluded that the particle formed in a region of the protoplanetary disk not far from where Earth is now, then made a journey closer to the sun, where it was progressively hotter, only to later reverse course and wash up in cooler parts farther from the young sun. Eventually, it was incorporated into an asteroid, which later broke apart into pieces. Some of those pieces were captured by Earth's gravity and fell as meteorites.

The samples for this study were taken from the inside of a meteorite and are considered primitive - in other words, unaffected by environmental influences. Such primitive material is believed to not have undergone any significant changes since it first formed more than 4.5 billion years ago, which is rare. Whether similar objects occur in asteroid Bennu, samples of which will be returned to Earth by the UArizona-led OSIRIS-REx mission in 2023, remains to be seen. Until then, scientists rely on samples that fall to Earth via meteorites.

"This material is our only record of what happened 4.567 billion years ago in the solar nebula," said Venkat Manga, a co-author of the paper and an assistant research professor in the UArizona Department of Materials Science and Engineering. "Being able to look at the microstructure of our sample at different scales, down to the length of individual atoms, is like opening a book."

The authors said that studies like this one could bring planetary scientists a step closer to "a grand model of planet formation" - a detailed understanding of the material moving around the disk, what it is composed of, and how it gives rise to the sun and the planets.

Powerful radio telescopes like the Atacama Large Millimeter/submillimeter Array, or ALMA, in Chile now allow astronomers to see stellar systems as they evolve, Zega said.

"Perhaps at some point we can peer into evolving disks, and then we can really compare our data between disciplines and begin answering some of those really big questions," Zega said. "Are these dust particles forming where we think they did in our own solar system? Are they common to all stellar systems? Should we expect the pattern we see in our solar system - rocky planets close to the central star and gas giants farther out - in all systems?

"It's a really interesting time to be a scientist when these fields are evolving so rapidly," he added. "And it's awesome to be at an institution where researchers can form transdisciplinary collaborations among leading astronomy, planetary and materials science departments at the same university."

A team of scientists using the Atacama Large Millimeter/submillimeter Array (ALMA) to study the young star Elias 2-27 have confirmed that gravitational instabilities play a key role in planet formation, and have for the first time directly measured the mass of protoplanetary disks using gas velocity data, potentially unlocking one of the mysteries of planet formation. The results of the research are published today in two papers in The Astrophysical Journal.

Protoplanetary disks--planet-forming disks made of gas and dust that surround newly formed young stars--are known to scientists as the birthplace of planets. The exact process of planet formation, however, has remained a mystery. The new research, led by Teresa Paneque-Carreño--a recent graduate of the Universidad de Chile and PhD student at the University of Leiden and the European Southern Observatory, and the primary author on the first of the two papers--focuses on unlocking the mystery of planet formation.

During observations, scientists confirmed that the Elias 2-27 star system--a young star located less than 400 light-years away from Earth in the constellation Ophiuchus--was exhibiting evidence of gravitational instabilities which occur when planet-forming disks carry a large fraction of the system's stellar mass. "How exactly planets form is one of the main questions in our field. However, there are some key mechanisms that we believe can accelerate the process of planet formation," said Paneque-Carreño. "We found direct evidence for gravitational instabilities in Elias 2-27, which is very exciting because this is the first time that we can show kinematic and multi-wavelength proof of a system being gravitationally unstable. Elias 2-27 is the first system that checks all of the boxes."

Elias 2-27's unique characteristics have made it popular with ALMA scientists for more than half a decade. In 2016, a team of scientists using ALMA discovered a pinwheel of dust swirling around the young star. The spirals were believed to be the result of density waves, commonly known to produce the recognizable arms of spiral galaxies--like the Milky Way Galaxy--but at the time, had never before been seen around individual stars.

"We discovered in 2016 that the Elias 2-27 disk had a different structure from other already studied systems, something not observed in a protoplanetary disk before: two large-scale spiral arms. Gravitational instabilities were a strong possibility, but the origin of these structures remained a mystery and we needed further observations," said Laura Pérez, Assistant Professor at the Universidad de Chile and the principal investigator on the 2016 study. Together with collaborators, she proposed further observations in multiple ALMA bands that were analyzed with Paneque-Carreño as a part of her M.Sc. thesis at Universidad de Chile.

In addition to confirming gravitational instabilities, scientists found perturbations--or disturbances--in the star system above and beyond theoretical expectations. "There may still be new material from the surrounding molecular cloud falling onto the disk, which makes everything more chaotic," said Paneque-Carreño, adding that this chaos has contributed to interesting phenomena that have never been observed before, and for which scientists have no clear explanation. "The Elias 2-27 star system is highly asymmetric in the gas structure. This was completely unexpected, and it is the first time we've observed such vertical asymmetry in a protoplanetary disk."

Cassandra Hall, Assistant Professor of Computational Astrophysics at the University of Georgia, and a co-author on the research, added that the confirmation of both vertical asymmetry and velocity perturbations--the first large-scale perturbations linked to spiral structure in a protoplanetary disk--could have significant implications for planet formation theory. "This could be a 'smoking gun' of gravitational instability, which may accelerate some of the earliest stages of planet formation. We first predicted this signature in 2020, and from a computational astrophysics point of view, it's exciting to be right."

Paneque-Carreño added that while the new research has confirmed some theories, it has also raised new questions. "While gravitational instabilities can now be confirmed to explain the spiral structures in the dust continuum surrounding the star, there is also an inner gap, or missing material in the disk, for which we do not have a clear explanation."

One of the barriers to understanding planet formation was the lack of direct measurement of the mass of planet-forming disks, a problem addressed in the new research. The high sensitivity of ALMA Band 6, paired with Bands 3 and 7, allowed the team to more closely study the dynamical processes, density, and even the mass of the disk. "Previous measurements of protoplanetary disk mass were indirect and based only on dust or rare isotopologues. With this new study, we are now sensitive to the entire mass of the disk," said Benedetta Veronesi--a graduate student at the University of Milan and postdoctoral researcher at École normale supérieure de Lyon, and the lead author on the second paper. "This finding lays the foundation for the development of a method to measure disk mass that will allow us to break down one of the biggest and most pressing barriers in the field of planet formation. Knowing the amount of mass present in planet-forming disks allows us to determine the amount of material available for the formation of planetary systems, and to better understand the process by which they form."

Although the team has answered a number of key questions about the role of gravitational instability and disk mass in planet formation, the work is not yet done. "Studying how planets form is difficult because it takes millions of years to form planets. This is a very short time-scale for stars, which live thousands of millions of years, but a very long process for us," said Paneque-Carreño. "What we can do is observe young stars, with disks of gas and dust around them, and try to explain why these disks of material look the way they do. It's like looking at a crime scene and trying to guess what happened. Our observational analysis paired with future in-depth analysis of Elias 2-27 will allow us to characterize exactly how gravitational instabilities act in planet-forming disks, and gain more insight into how planets are formed."

An international team of scientists, led by astrophysicists from the University of Bath in the UK, has measured the magnetic field in a far-off Gamma-Ray Burst, confirming for the first time a decades-long theoretical prediction - that the magnetic field in these blast waves becomes scrambled after the ejected material crashes into, and shocks, the surrounding medium.

Black holes are formed when massive stars (at least 40 times larger than our Sun) die in a catastrophic explosion that powers a blast wave. These extremely energetic events drive out material at velocities close to the speed of light, and power bright, short-lived gamma-ray flashes that can be detected by satellites orbiting the Earth - hence their name, Gamma-Ray Bursts (GRBs).

Magnetic fields may be threaded through the ejected material and, as the spinning black hole forms, these magnetic fields twist into corkscrew shapes that are thought to focus and accelerate the ejected material.

The magnetic fields can't be seen directly, but their signature is encoded in the light produced by charged particles (electrons) that whiz around the magnetic field lines. Earth-bound telescopes capture this light, which has travelled for millions of years across the Universe.

Head of Astrophysics at Bath and gamma-ray expert Professor Carole Mundell, said: "We measured a special property of the light - polarisation - to directly probe the physical properties of the magnetic field powering the explosion. This is a great result and solves a long-standing puzzle of these extreme cosmic blasts - a puzzle I've been studying for a long time."

CAPTURING THE LIGHT EARLY

The challenge is to capture the light as soon as possible after a burst and decode the physics of the blast, the prediction being that any primordial magnetics fields will ultimately be destroyed as the expanding shock front collides with the surrounding stellar debris.

This model predicts light with high levels of polarisation (>10%) soon after the burst when the large-scale primordial field is still intact and driving the outflow. Later, the light should be mostly unpolarised as the field is scrambled in the collision.

Mundell's team was first to discover highly polarised light minutes after the burst that confirmed the presence of primordial fields with large-scale structure. But the picture for expanding forward shocks has proved more controversial.

Teams who observed GRBs in slower time - hours to a day after a burst - found low polarisation and concluded the fields had long-since been destroyed, but could not say when or how. In contrast, a team of Japanese astronomers announced an intriguing detection of 10% polarised light in a GRB, which they interpreted as a polarised forward shock with long-lasting ordered magnetic fields.

Lead author of the new study, Bath PhD student Nuria Jordana-Mitjans, said: "These rare observations were difficult to compare, as they probed very different timescales and physics. There was no way to reconcile them in the standard model."

The mystery remained unsolved for over a decade, until the Bath team's analysis of GRB 141220A.

In the new paper, published today in the Monthly Notices of the Royal Astronomical Society, Professor Mundell's team report the discovery of very low polarisation in forward-shock light detected just 90 seconds after the blast of GRB 141220A. The super-speedy observations were made possible by the team's intelligent software on the fully autonomous robotic Liverpool Telescope and the novel RINGO3 polarimeter - the instrument that logged the GRB's colour, brightness, polarisation and rate of fade. Putting together this data, the team was able to prove that:

The light originated in the forward shock.

The magnetic field length scales were much smaller than the Japanese team inferred.

The blast was likely powered by the collapse of ordered magnetic fields in the first moments of the formation of a new black hole.

The mysterious detection of polarisation by the Japanese team could be explained by a contribution of polarised light from the primordial magnetic field before it was destroyed in the shock.

Ms Jordana-Mitjans said: "This new study builds on our research that has shown the most powerful GRBs can be powered by large-scale ordered magnetic fields, but only the fastest telescopes will catch a glimpse of their characteristic polarisation signal before they are lost to the blast."

Professor Mundell added: "We now need to push the frontiers of technology to probe the earliest moments of these blasts, capture statistically significant numbers of bursts for polarisation studies and put our research into the wider context of real-time multimessenger follow-up of the extreme Universe."

The demand for detecting infrared (IR) light, invisible to human eyes, is constantly growing, due to a wide variety of applications ranging from food quality control and remote sensing to night vision devices and lidar. Commercial IR cameras require the conversion of infrared light to electrons and the projection of the resultant image on a display. This display blocks the transmission of visible light, thereby disrupting normal vision. Moreover, such IR detectors require low temperature and even cryogenic cooling due to the low energies of the IR photons, making IR detectors bulky and heavy.

An all-optical alternative to traditional cameras is the use of a nonlinear optical process to convert IR light into visible. In this case, electrical signals are no longer involved in the IR detection process, and the image, converted to the visible, can be captured by eye or phone-type camera. The optical process employed in this technique is nonlinear sum-frequency generation (SFG). In the SFG process, two incident photons, one of them in the IR spectrum, interact within a nonlinear material to generate emission at higher and visible frequencies. However, in the usual approaches this conversion relies on bulky and expensive nonlinear crystals.

A very attractive platform to overcome these limitations is the use of ultrathin nanocrystal layers known as metasurfaces. Metasurfaces are planar arrays of densely packed nanoantennas, designed to manipulate various properties of the incident light including its frequency. Among various examples, dielectric and semiconductor metasurfaces have shown great promise to enhance nonlinear optical processes at the nanoscale. Such metasurfaces can exhibit enhanced frequency conversion due to the excitation of optical resonances and good coupling to free space. Thus, the use of nonlinear metasurfaces is a promising way to up-convert IR photons to visible and thereby image IR objects through coherent conversion using ultrathin and ultralight devices. Importantly, transparent metasurfaces could perform IR imaging in a transmission configuration and simultaneously transmit visible light to allow for normal vision.

With this idea in mind, researchers from The Australian National University, Nottingham Trent University, and collaborators worldwide managed to demonstrate IR imaging via nonlinear metasurfaces composed of small semiconductor nanocrystals. As reported in Advanced Photonics, the researchers designed a multiresonant metasurface to enhance the field at all the frequencies participating in the SFG process. The designed metasurface was fabricated and transferred to a transparent glass, forming a layer of nanocrystals on the glass surface.

In the experiment, an IR image of a Siemens-star target illuminated the metasurfaces. The IR image of the target was mixed with a second beam and, through the SFG process, up-converted to a visible wavelength at 550 nm (green light). The visible green images, captured with a conventional camera, correspond to different transverse positions of the target, including the case when the target was fully removed from the path of the IR beam and the SFG emission from the metasurface was observed. Despite different parts of the IR signal beam being up-converted by independent nanocrystals composing the metasurface, the images were well reproduced into the visible.

The proposed metasurface-based IR imaging approach offers novel opportunities not possible in conventional up-conversion systems. For example, the use of counter-propagating excitation beams, as well as incidence at different angles and, most importantly, multicolor IR imaging by an appropriately designed metasurface. Therefore, the results obtained by the researchers can benefit the future development of compact night vision instruments and sensor devices, offering an ultrathin and ultracompact platform and new functionalities such as multicolor IR imaging at room temperature.

Acoustic waves in gases, liquids, and solids usually travel at an almost constant speed of sound. So-called rotons are an exception: their speed of sound changes significantly with the wavelength, and it is also possible that the waves travel backwards. Researchers at Karlsruhe Institute of Technology (KIT) are studying the possibilities of using rotons in artificial materials. These computer-designed metamaterials, produced by ultra-precise 3D laser printing, might be used in the future to manipulate or direct sound in ways that have never been possible before. A report on the researchers' work has been published in Nature Communications. (DOI: 10.1038/s41467-021-23574-2)

Rotons are quasiparticles, which means that they behave similarly to free particles. Unlike ordinary acoustic waves in gases, liquids, and solids, the speed of sound changes significantly with the wavelength. In addition, certain frequencies generate three different partial waves. "The slowest among them is a backward wave: the energy flow and the wavefronts run in exactly opposite directions," explains Professor Martin Wegener from the Institute of Applied Physics (APH) and KIT's Institute of Nanotechnology (INT). Understanding and benefiting from quasiparticles such as rotons is one of the great challenges of quantum physics. Physicist Lev Landau, who won a Nobel Prize in 1962 for his groundbreaking work, predicted their existence in the context of superfluidity, a condition in which a fluid loses its internal friction and becomes thermally conductive in a nearly ideal way. Until now, rotons could only be observed under special quantum-physical conditions at very low temperatures - and were therefore not suitable to technical applications.

Rotons without Any Quantum Effects

This might change in the future: in the 3D Matter Made to Order Cluster of Excellence of KIT and the University of Heidelberg, a group of researchers is working on metamaterials that "grow" rotons. Metamaterials exhibit optical, acoustic, electrical, or magnetic properties that are not found in nature. The scientists propose an artificial material that can produce rotons without any quantum effects under normal ambient conditions and at almost random frequencies or wavelengths. Thus, it might be possible in the future to better manipulate sound waves in air or in materials, for example, to bounce them back, redirect them, or create echoes. These materials have not been demonstrated experimentally yet; however, it should be possible to produce them by using technologies such as ultra-precise 3D laser printing. "We have even made some of these metamaterials in the meantime," Professor Martin Wegener says. "Currently, we are working intensively on the direct experimental proof for the existence of rotons."

3D printing - the Gateway from the Digital to the Physical World

Dr. Yi Chen, lead author of the publication, explains that the researchers relied on a combination of reflection, many discussions and numerical simulations and optimizations to devise the computer-aided virtual design of materials with such novel properties. His work as a post-doctoral researcher at KIT is funded by the Alexander von Humboldt Foundation and is integrated into a Helmholtz program entitled "Material Systems Engineering" launched in 2021. "In general, our dream is to design materials on the computer and then turn them directly into reality - without years of trial and error. So 3D printing is just an automated converter, as it were, from the digital to the physical world," Professor Martin Wegener explains.(or)

For nearly half a century, astrophysicists and organic chemists have been on the hunt for the origins of C6H6, the benzene ring – an elegant, hexagonal molecule comprised of 6 carbon and 6 hydrogen atoms.

Astrophysicists say that the benzene ring could be the fundamental building block of polycylic aromatic hydrocarbons or PAHs, the most basic materials formed from the explosion of dying, carbon-rich stars. That swirling mass of matter would eventually give shape to the earliest forms of carbon – precursors to molecules some scientists say are connected to the synthesis of the earliest forms of life on Earth.

Paradoxically, PAHs have a dark side, too. The industrial processes behind crude oil refineries and the inner-workings of gas-powered combustion engines can emit PAHs, which can snowball into toxic air pollutants like soot.

Exactly how the first benzene ring formed from stars in the early universe – and how combustion engines trigger the chemical reaction that alters the benzene ring into soot particle pollutants – have long mystified scientists.

But now, researchers at Lawrence Berkeley National Laboratory (Berkeley Lab), the University of Hawaii at Manoa, and Florida International University have demonstrated the first real-time measurement, using lab-based methods, of unstable particles called free radicals reacting under cosmic conditions, prompting elementary carbon and hydrogen atoms to coalesce into primal benzene rings.

The researchers say that their findings, recently published in the journal Science Advances, are key to understanding how the universe evolved with the growth of carbon compounds. That insight could also help the car industry make cleaner combustion engines.

A type of free radical called the propargyl radical (C3H3) is extremely reactive due to its propensity for losing an electron, and has been implicated in soot formation for decades. Researchers believed that the recombination of two free propargyl radicals, C3H3· + C3H3·, gave rise to the first aromatic ring, benzene.

The current study is the first demonstration of the so-called “radical propargyl self-reaction” under astrochemical and combustion conditions. Using a high-temperature, coin-sized chemical reactor called the “hot nozzle,” the researchers simulated the high-pressure, high-temperature environment inside a combustion engine as well as the hydrocarbon-rich atmosphere of Saturn’s moon Titan, and observed the formation of isomers – molecules with the same chemical formula but different atomic structures – from two propargyl radicals leading up to the benzene ring.

The hot-nozzle technique, which co-senior author Musahid Ahmed, senior staff scientist in Berkeley Lab’s Chemical Sciences Division, adapted 10 years ago at Berkeley Lab’s Advanced Light Source (ALS) for synchrotron experiments, relies on vacuum ultraviolet (VUV) spectroscopy to detect individual isomers. The ALS is a type of particle accelerator known as a synchrotron that generates extremely bright beams of light ranging from infrared through X-rays.

The researchers steered the technique to arrest the propargyl radical self-reaction – which unfolds within microseconds – just before larger PAHs and subsequent soot form. The compelling result supports predictions from experiments led by co-senior author Ralf Kaiser, professor of chemistry at the University of Hawaii at Manoa, and quantum chemistry simulations formulated by co-senior author Alexander Mebel, professor of chemistry at Florida International University.

They believe that the finding could one day lead to cleaner combustion engines. Having more efficient gas engines, some analysts say, is still important, because it may take another 25 years before we can replace the entire fleet of gas cars with electric vehicles (EVs). Furthermore, equipping airplanes and the gas-powered component of hybrid plug-in EVs with cleaner combustion engines could help reduce CO2 emissions contributing to climate change.

Ahmed said he plans to extend the methods employed to study PAH growth, and probe other systems of relevance to the DOE mission, such as water desalination and environmental science.

“We’d also like to go and catch a buckyball, C60, one of nature’s biggest clues to the secrets behind symmetry,” Ahmed said.

Kaiser added that their research could help astronomers plot a carbon map of the universe, and zero in on the cosmic origins behind DNA’s carbon frameworks.