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Organic material from Mars reveals the likely origin of life’s building blocks

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Organic material from Mars reveals the likely origin of life’s building blocks


Two samples from Mars together deliver the “smoking gun” in a new study showing the origin of Martian organic material. The study presents solid evidence for a prediction made over a decade ago by University of Copenhagen researchers that could be key to understanding how organic molecules, the foundation of life, were first formed here on Earth.

In a meteor crater on the red planet, a solitary robot is moving about. Right now it is probably collecting soil samples with a drill and a robotic arm, as it has quite a habit of doing. NASA’s Curiosity rover has been active on Mars as the extended arm of science for nearly 12 years, and it continues to make discoveries that surprise and challenge scientists’ understanding of both Mars and our own world here on Earth.

Most recently, the discovery of sedimentary organic material with particular properties has had many researchers scratching their heads. The properties of these carbon-based materials, in particular the ratio of its carbon isotopes, surprised researchers.

Organic materials with such properties, if found on Earth, would typically be a sign of microorganisms, but they can also be the result of non-biological, chemical processes. The find obviously had researchers scrambling for a clear answer, but nothing seemed to fit.

However, for the research collaboration behind a new study published in Nature Geoscience, there has been little hair scratching and much enthusiasm.

In fact, the discovery on Mars provided the missing piece that made everything fall into place for this group of researchers from the University of Copenhagen and the Tokyo Institute of Technology.

As co-author and chemistry professor Matthew Johnson puts it, it is “the smoking gun” needed to confirm a decade old theory of his about so-called photolysis in Mars’ atmosphere.

With the Curiosity sample, the new research is able to prove with reasonable certainty that the Sun broke down CO2 in the Martian atmosphere billions of years ago — as the old theory predicted. And that the resulting carbon monoxide gradually reacted with other chemicals in the atmosphere synthesizing complex molecules — and thus providing Mars with organic materials.

“Such carbon-based complex molecules are the prerequisite of life, the building blocks of life one might say. So, this it is a bit like the old debate about which came first, the chicken or the egg. We show that the organic material found on Mars has been formed through atmospheric photochemical reactions — without life that is. This is the ‘egg’, a prerequisite of life. It still remains to be shown whether or not this organic material resulted in life on the Red Planet.” said Johnson and continued:

“Additionally because Earth, Mars and Venus had very similar CO2 rich atmospheres long ago when this photolysis took place, it can also prove important for our understanding of how life began on Earth,” said Professor Matthew Johnson from Department of Chemistry at University of Copenhagen.

Two pieces separated by 50 Million Kilometers — one puzzle solved

12 years ago Johnson and two colleagues used simulations based on quantum mechanics to determine what happens when a CO2 rich atmosphere is exposed to the UV-light of the Sun, in a process known as photolysis.

Basically, on Mars around 20% of the CO2 is split into oxygen and carbon monoxide. But carbon has two stable isotopes: carbon-12 and carbon-13. Usually they are present in a ratio of one carbon-13 for every 99 carbon-12. However, photolysis works faster for the lighter carbon-12, so the carbon monoxide produced by photolysis has less carbon-13 (is depleted), and the left over CO2 has more (is enriched).

Because of this, Johnson and his colleagues were able to make very precise predictions of the ratio of carbon isotopes after photolysis. And this gave them two distinctive fingerprints to look for. One of these was identified in a different Martian sample, years ago.

“We actually have a piece of Mars here on Earth, which was knocked off that planet by a meteorite, and then became one itself, when it landed here on Earth. This meteorite, called Allan Hills 84001 for the place in Antarctica where it was found, contains carbonate minerals that form from CO2 in the atmosphere. The smoking gun here is that the ratio of carbon isotopes in it exactly matches our predictions in the quantum chemical simulations, but there was a missing piece in the puzzle. We were missing the other product of this chemical process to confirm the theory, and that’s what we’ve now obtained,” says Matthew Johnson.

The carbon in the Allan Hills meteorite is enriched in carbon-13, which makes it the mirror image of the depletion in carbon-13 that has now been measured in the organic material found by Curiousity on Mars.

The new study has thus linked data from two samples, which researchers believe have the same origin in Mars’ childhood but were found more than 50 million kilometers apart.

“There is no other way to explain both the carbon-13 depletion in the organic material and the enrichment in the Martian meteorite, both relative to the composition of volcanic CO2 emitted on Mars, which has a constant composition, similar as for Earth’s volcanos, and serves as a baseline,” said Johnson

Hope to find the same evidence on Earth

Because the organic material contains this isotopic “fingerprint” of where it came from, researchers are able to trace the source of the carbon in the organic material to the carbon monoxide formed by photolysis in the atmosphere. But this also reveals a lot about what happened to it in between.

“This shows that carbon monoxide is the starting point for the synthesis of organic molecules in these kinds of atmospheres. So we have an important conclusion about the origin of life’s building blocks. Although so far only on Mars,” said Matthew Johnson.

Researchers hope to find the same isotopic evidence on Earth, but this has yet to happen, and it could be a much bigger challenge because our geological development has changed the surface significantly compared to Mars, Johnson explains.

“It is reasonable to assume that the photolysis of CO2 was also a prerequisite for the emergence of life here on Earth, in all its complexity. But we have not yet found this “smoking gun” material here on Earth to prove that the process took place. Perhaps because Earth’s surface is much more alive, geologically and literally, and therefore constantly changing. But it is a big step that we have now found it on Mars, from a time when the two planets were very similar,” says Matthew Johnson.

Facts: Organic material

The sample found on Mars contains deposits of so-called organic material. To laymen this may sound more exciting than it is. Organic material in a chemical context does not necessarily mean something living, as one might normally think. The term covers molecules that contain carbon and at least one other element and can easily exist without life. These molecules are rather the building blocks of life.

Facts: What is Photolysis

Photolysis means that the Sun’s UV rays provide molecules with energy to perform a chemical transformation. According to the research this happened in the Martian atmosphere, where 20% of CO2 molecules there were split into oxygen and carbon monoxide.

In earlier research, Johnson and colleagues showed that carbon dioxide containing the carbon-12 isotope is photolysed more quickly than the heavier isotope carbon-13.

Over time, CO is produced that is depleted in 13C, and 13C builds up in the remaining CO2. This results in so-called isotopic enrichment in CO2 and depletion in CO, like mirror images or each other or the two halves of a broken plate.

It is the fractionation ratio in carbon, which serves as evidence of photolysis in the two samples from Mars.

Facts: The oxygen painted Mars red

Photolysis of a CO2 molecule yields carbon monoxide (CO) and an oxygen atom (O). On Mars, only carbon monoxide remains, which is transformed into the organic material found by the Curiosity rover.

But where the oxygen has gone is also no secret. The oxygen combines into O2, which interacts with iron on Mars’ surface. The Red Planet is rust red due to oxidized iron.

Facts: Isotopes Have Different Weights

Isotopes are variants of the same element that have different weights because the nucleus contains more or fewer neutrons.

Carbon has two stable isotopes — Normally, about 99% of carbon has 6 protons and 6 neutrons in its nucleus (12C). About 1% has 6 protons and 7 neutrons instead (13C). The ratio can serve as a chemical fingerprint revealing what reactions the carbon has undergone.

Photolysis favors carbon-12, and a high concentration of the isotope can therefore indicate this process.

Extra Info: The Famous Mars Meteorite

The discovery of organic sediments on Mars with a low ratio of carbon-13 completes the puzzle of empirical evidence for the photolysis theory, since researchers already found the other part of that puzzle years ago in the famous meteorite, Allan Hills 84001. The meteorite contains carbonate with a heightened concentration of heavy carbon 13 isotopes.

Discovered in Antarctica 40 years ago by Roberta Score, the meteorite is believed to originate from the Red Planet and became particularly well known because it contains some deposits that led NASA researchers to announce in 1996 that they believed they had found traces of microscopic fossils of bacteria from Mars.

Today, the consensus is that these deposits are abiotic — that is, stemming from non-biological processes.

Extra info: Mars, Earth, and Venus Had the Same Atmosphere

According to researchers, Earth had approximately the same atmosphere as our neighboring planets Mars and Venus billions of years ago.

When the early planets Venus, Earth, and Mars eventually formed solid surfaces, researchers believe they began to release large amounts of CO2 from extreme volcanic activity. That’s how they formed their first atmospheres with large concentrations of the gas. Oxygen had not yet become part of the atmosphere; this happened later on Earth, after the emergence of life.

The photolysis theory states that UV rays from the sun then start a chain of chemical reactions. A chain that starts with the breakdown of CO2 into carbon monoxide, which is the building block for a multitude of other chemical compounds.

Thus, with the help of the Sun, the foundation for the many carbon compounds and complex molecules we have today was formed — in the case of Earth, the foundation for life.

“Since then the fate of the three planets has been significantly different. Earth’s carbon dioxide reacted with our large amount of surface water and much of it deposited over time as carbonate rocks like limestone, leaving the atmosphere dominated by nitrogen, as we have today. Life arose, and microorganisms produced oxygen, which, among other things, created our ozone layer, while Mars and Venus still have very CO2-dominant atmospheres today,” explains Matthew Johnson.

Today, Venus has a very dense and toxic atmosphere primarily of CO2, which gives it a surface temperature of around 450 degrees Celsius.

On Mars, the atmosphere has become much thinner compared to Earth’s, and has left a desert landscape.



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Waste Styrofoam can now be converted into polymers for electronics

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University of Delaware and Argonne National Laboratory have come up with a chemical reaction that can convert Styrofoam into a high-value conducting polymer known as PEDOT:PSS. In a new paper published in JACS Au, the study demonstrates how upgraded plastic waste can be successfully incorporated into functional electronic devices, including silicon-based hybrid solar cells and organic electrochemical transistors.

The research group of corresponding author Laure Kayser, assistant professor in the Department of Materials Science and Engineering in UD’s College of Engineering with a joint appointment in the Department of Chemistry and Biochemistry in the College of Arts and Sciences, regularly works with PEDOT:PSS, a polymer that has both electronic and ionic conductivity, and was interested in finding ways to synthesize this material from plastic waste.

After connecting with Argonne chemist David Kaphan during an event hosted by UD’s research office, the research teams at UD and Argonne began evaluating the hypothesis that PEDOT:PSS could be made by sulfonating polystyrene, a synthetic plastic found in many types of disposable containers and packing materials.

Sulfonation is a common chemical reaction where a hydrogen atom is replaced by sulfonic acid; the process is used to create a variety of products such as dyes, drugs and ion exchange resins. These reactions can either be “hard” (with higher conversion efficiency but that require caustic reagents) or “soft” (a less efficient method but one that uses milder materials).

In this paper, the researchers wanted to find something in the middle: “A reagent that is efficient enough to get really high degrees of functionalization but that doesn’t mess up your polymer chain,” Kayser explained.

The researchers first turned to a method described in a previous study for sulfonating small molecules, one that showed promising results in terms of efficiency and yield, using 1,3-Disulfonic acid imidazolium chloride ([Dsim]Cl). But adding functional groups onto a polymer is more challenging than for a small molecule, the researchers explained, because not only are unwanted byproducts harder to separate, any small errors in the polymer chain can change its overall properties.

To address this challenge, the researchers embarked on many months of trial and error to find the optimal conditions that minimized side reactions, said Kelsey Koutsoukos, a materials science doctoral candidate and second author of this paper.

“We screened different organic solvents, different molar ratios of the sulfonating agent, and evaluated different temperatures and times to see which conditions were the best for achieving high degrees of sulfonation,” he said.

The researchers were able to find reaction conditions that resulted in high polymer sulfonation, minimal defects and high efficiency, all while using a mild sulfonating agent. And because the researchers were able to use polystyrene, specifically waste Styrofoam, as a starting material, their method also represents an efficient way to convert plastic waste into PEDOT:PSS.

Once the researchers had PEDOT:PSS in hand, they were able to compare how their waste-derived polymer performed compared to commercially available PEDOT:PSS.

“In this paper, we looked at two devices — an organic electronic transistor and a solar cell,” said Chun-Yuan Lo, a chemistry doctoral candidate and the paper’s first author. “The performance of both types of conductive polymers was comparable, and shows that our method is a very eco-friendly approach for converting polystyrene waste into high-value electronic materials.”

Specific analyses conducted at UD included X-ray photoelectron spectroscopy (XPS) at the surface analysis facility, film thickness analysis at the UD Nanofabrication Facility, and solar cell evaluation at the Institute of Energy Conversion. Argonne’s advanced spectroscopy equipment, such as carbon NMR, was used for detailed polymer characterization. Additional support was provided by materials science and engineering professor Robert Opila for solar cell analysis and by David C. Martin, the Karl W. and Renate Böer Chaired Professor of Materials Science and Engineering, for the electronic device performance analyses.

One unexpected finding related to the chemistry, the researchers added, is the ability to use stoichiometric ratios during the reaction.

“Typically, for sulfonation of polystyrene, you have to use an excess of really harsh reagents. Here, being able to use a stoichiometric ratio means that we can minimize the amount of waste being generated,” Koutsoukos said.

This finding is something the Kayser group will be looking into further as a way to “fine-tune” the degree of sulfonation. So far, they’ve found that by varying the ratio of starting materials, they can change the degree of sulfonation on the polymer. Along with studying how this degree of sulfonation impacts the electrical properties of PEDOT:PSS, the team is interested in seeing how this fine-tuning capability can be used for other applications, such as fuel cells or water filtration devices, where the degree of sulfonation greatly impacts a material’s properties.

“For the electronic devices community, the key takeaway is that you can make electronic materials from trash, and they perform just as well as what you would purchase commercially,” Kayser said. “For the more traditional polymer scientists, the fact that you can very efficiently and precisely control the degree of sulfonation is going to be of interest to a lot of different communities and applications.”

The researchers also see great potential for how this research can contribute to ongoing global sustainability efforts by providing a new way to convert waste products into value-added materials.

“Many scientists and researchers are working hard on upcycling and recycling efforts, either by chemical or mechanical means, and our study provides another example of how we can address this challenge,” Lo said.

The complete list of co-authors includes Chun-Yuan Lo, Kelsey Koutsoukos, Dan My Nguyen, Yuhang Wu, David Angel Trujillo, Tulaja Shrestha, Ethan Mackey, Vidhika Damani, Robert Opila, David Martin, and Laure Kayser from the University of Delaware and Tabitha Miller, Uddhav Kanbur, and David Kaphan from Argonne National Laboratory.



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New snake discovery rewrites history, points to North America’s role in snake evolution

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A new species of fossil snake unearthed in Wyoming is rewriting our understanding of snake evolution. The discovery, based on four remarkably well-preserved specimens found curled together in a burrow, reveals a new species named Hibernophis breithaupti. This snake lived in North America 34 million years ago and sheds light on the origin and diversification of boas and pythons.

Hibernophis breithaupti has unique anatomical features, in part because the specimens are articulated — meaning they were found all in one piece with the bones still arranged in the proper order — which is unusual for fossil snakes. Researchers believe it may be an early member of Booidea, a group that includes modern boas and pythons. Modern boas are widespread in the Americas, but their early evolution is not well understood.These new and very complete fossils add important new information, in particular, on the evolution of small, burrowing boas known as rubber boas.

Traditionally, there has been much debate on the evolution of small burrowing boas. Hibernophis breithaupti shows that northern and more central parts of North America might have been a key hub for their development. The discovery of these snakes curled together also hints at the oldest potential evidence for a behavior familiar to us today — hibernation in groups.

“Modern garter snakes are famous for gathering by the thousands to hibernate together in dens and burrows,” says Michael Caldwell, a U of A paleontologist who co-led the research along with his former graduate student Jasmine Croghan, and collaborators from Australia and Brazil. “They do this to conserve heat through the effect created by the ball of hibernating animals. It’s fascinating to see possible evidence of such social behavior or hibernation dating back 34 million years.”



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Good timing: Study unravels how our brains track time

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Ever hear the old adage that time flies when you’re having fun? A new study by a team of UNLV researchers suggests that there’s a lot of truth to the trope.

Many people think of their brains as being intrinsically synced to the human-made clocks on their electronic devices, counting time in very specific, minute-by-minute increments. But the study, published this month in the latest issue of the peer-reviewed Cell Press journal Current Biology, showed that our brains don’t work that way.

By analyzing changes in brain activity patterns, the research team found that we perceive the passage of time based on the number of experiences we have — not some kind of internal clock. What’s more, increasing speed or output during an activity appears to affect how our brains perceive time.

“We tell time in our own experience by things we do, things that happen to us,” said James Hyman, a UNLV associate professor of psychology and the study’s senior author. “When we’re still and we’re bored, time goes very slowly because we’re not doing anything or nothing is happening. On the contrary, when a lot of events happen, each one of those activities is advancing our brains forward. And if this is how our brains objectively tell time, then the more that we do and the more that happens to us, the faster time goes.”

Methodology and Findings

The findings are based on analysis of activity in the anterior cingulate cortex (ACC), a portion of the brain important for monitoring activity and tracking experiences. To do this, rodents were tasked with using their noses to respond to a prompt 200 times.

Scientists already knew that brain patterns are similar, but slightly different, each time you do a repetitive motion, so they set out to answer: Is it possible to detect whether these slight differences in brain pattern changes correspond with doing the first versus 200th motion in series? And does the amount of time it takes to complete a series of motions impact brain wave activity?

By comparing pattern changes throughout the course of the task, researchers observed that there are indeed detectable changes in brain activity that occur as one moves from the beginning to middle to end of carrying out a task. And regardless of how slowly or quickly the animals moved, the brain patterns followed the same path. The patterns were consistent when researchers applied a machine learning-based mathematical model to predict the flow of brain activity, bolstering evidence that it’s experiences — not time, or a prescribed number of minutes, as you would measure it on a clock — that produce changes in our neurons’ activity patterns.

Hyman drove home the crux of the findings by sharing an anecdote of two factory workers tasked with making 100 widgets during their shift, with one worker completing the task in 30 minutes and the other in 90 minutes.

“The length of time it took to complete the task didn’t impact the brain patterns. The brain is not a clock; it acts like a counter,” Hyman explained. “Our brains register a vibe, a feeling about time. …And what that means for our workers making widgets is that you can tell the difference between making widget No. 85 and widget No. 60, but not necessarily between No. 85 and No. 88.”

But exactly “how” does the brain count? Researchers discovered that as the brain progresses through a task involving a series of motions, various small groups of firing cells begin to collaborate — essentially passing off the task to a different group of neurons every few repetitions, similar to runners passing the baton in a relay race.

“So, the cells are working together and over time randomly align to get the job done: one cell will take a few tasks and then another takes a few tasks,” Hyman said. “The cells are tracking motions and, thus, chunks of activities and time over the course of the task.”

And the study’s findings about our brains’ perception of time applies to activities-based actions other than physical motions too.

“This is the part of the brain we use for tracking something like a conversation through dinner,” Hyman said. “Think of the flow of conversation and you can recall things earlier and later in the dinner. But to pick apart one sentence from the next in your memory, it’s impossible. But you know you talked about one topic at the start, another topic during dessert, and another at the end.”

By observing the rodents who worked quickly, scientists also concluded that keeping up a good pace helps influence time perception: “The more we do, the faster time moves. They say that time flies when you’re having fun. As opposed to having fun, maybe it should be ‘time flies when you’re doing a lot’.”

Takeaways

While there’s already a wealth of information on brain processes over very short time scales of less than a second, Hyman said that the UNLV study is groundbreaking in its examination of brain patterns and perception of time over a span of just a few minutes to hours — “which is how we live much of our life: one hour at a time. ”

“This is among the first studies looking at behavioral time scales in this particular part of the brain called the ACC, which we know is so important for our behavior and our emotions,” Hyman said.

The ACC is implicated in most psychiatric and neurodegenerative disorders, and is a concentration area for mood disorders, PTSD, addiction, and anxiety. ACC function is also central to various dementias including Alzheimer’s disease, which is characterized by distortions in time. The ACC has long been linked to helping humans with sequencing events or tasks such as following recipes, and the research team speculates that their findings about time perception might fall within this realm.

While the findings are a breakthrough, more research is needed. Still, Hyman said, the preliminary findings posit some potentially helpful tidbits about time perception and its likely connection to memory processes for everyday citizens’ daily lives. For example, researchers speculate that it could lend insights for navigating things like school assignments or even breakups.

“If we want to remember something, we may want to slow down by studying in short bouts and take time before engaging in the next activity. Give yourself quiet times to not move,” Hyman said. “Conversely, if you want to move on from something quickly, get involved in an activity right away.”

Hyman said there’s also a huge relationship between the ACC, emotion, and cognition. Thinking of the brain as a physical entity that one can take ownership over might help us control our subjective experiences.

“When things move faster, we tend to think it’s more fun — or sometimes overwhelming. But we don’t need to think of it as being a purely psychological experience, as fun or overwhelming; rather, if you view it as a physical process, it can be helpful,” he said. “If it’s overwhelming, slow down or if you’re bored, add activities. People already do this, but it’s empowering to know it’s a way to work your own mental health, since our brains are working like this already.”



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