“This study is the first to demonstrate, using a physical model, that the first-order features of Earth’s lower mantle structure were established four billion years ago, very soon after the planet came into existence,” says lead author Faculty of Science Assistant Professor Charles-Édouard Boukaré in the Department of Physics and Astronomy at York.

The mantle is the rocky envelopment that surrounds the iron core of rocky planets. The structure and dynamics of the Earth’s lower mantle play a major role throughout Earth’s history as it dictates, among others, the cooling of the Earth’s core where the Earth’s magnetic field is generated.

Boukaré originally from France, worked with research colleagues from Paris on the paper, Solidification of Earth’s mantle led inevitably to a basal magma ocean, published today in Nature.

Boukaré says that while seismology, geodynamics, and petrology have helped answer many questions about the present-day thermochemical structure of Earth’s interior, a key question remained: how old are these structures, and how did they form? Trying to answer this, he says, is much like looking at a person in the form of an adult versus a child and understanding how the energetic conditions will not be the same.

“If you take kids, sometimes they do crazy things because they have a lot of energy, like planets when they are young. When we get older, we don’t do as many crazy things, because our activity or level of energy decreases. So, the dynamic is really different, but there are some things that we do when we are really young that might affect our entire life,” he says “It’s the same thing for planets. There are some aspects of the very early evolution of planets that we can actually see in their structure today.”

To better understand old planets, we must first learn how young planets behave.

Since simulations of the Earth’s mantle focus mostly on present-day solid-state conditions, Boukaré had to develop a novel model to explore the early days of Earth when the mantle was much hotter and substantially molten, work that he has been doing since his PhD.

Boukaré’s model is based on a multiphase flow approach that allows for capturing the dynamics of magma solidification at a planetary scale. Using his model, he studied how the early mantle transitioned from a molten to a solid state. Boukaré and his team were surprised to discover that most of the crystals formed at low pressure, which he says creates a very different chemical signature than what would be produced at depth in a high-pressure environment. This challenges the prevailing assumptions in planetary sciences in how rocky planets solidify.

“Until now, we assumed the geochemistry of the lower mantle was probably governed by high-pressure chemical reactions, and now it seems that we need to account also for their low-pressure counterparts.”

Boukare says this work could also help predict the behaviour of other planets down the line.

“If we know some kind of starting conditions, and we know the main processes of planetary evolution, we can predict how planets will evolve.”

A U.S. Department of Energy-funded study, “Deconstruction of Rubber via C-H Amination and Aza-Cope Rearrangement,” recently published in Nature and led by Dr. Aleksandr Zhukhovitskiy, William R. Kenan, Jr. Fellow and Assistant Professor in the Department of Chemistry at UNC-Chapel Hill, introduces a novel chemical method for breaking down rubber waste. This pioneering technique utilizes C-H amination and a polymer rearrangement strategy to transform discarded rubber into valuable precursors for epoxy resins, offering an innovative and sustainable alternative to traditional recycling methods.

Rubber, including the synthetic kind used in tires, is composed of polymers cross-linked together into a three-dimensional network that behaves as a tough, flexible material. Recycling these materials is difficult due to the extensive cross-linking within the polymer structure, which gives rubber its durability but also makes it resistant to degradation. Traditional methods for breaking down rubber focus on two main approaches: de-vulcanization, which breaks sulfur cross-links but weakens the polymer’s mechanical properties, and cleavage of the polymer backbones using oxidative or catalytic methods, which often result in complex, low-value byproducts. Neither approach provides an efficient, scalable solution for repurposing rubber waste.

“Our research seeks to overcome these challenges by developing a method that breaks down rubber into functional materials that possess value even as a mixture,” said Dr. Zhukhovitskiy, who is the corresponding author of the study.

The researchers introduce a sulfur diimide reagent that enables the installation of amine groups at specific locations in the polymer chains. This step is crucial because it sets the stage for the subsequent backbone rearrangement. This chemical reaction reorganizes the polymer backbone, breaking down the rubber into soluble amine-functionalized materials that can be used to produce epoxy resins.

The researchers showed that their two-step process works very well. In a test with a model polymer, they broke it down significantly, reducing its molecular weight from 58,100 g/mol to about 400 g/mol. When they applied the method to used rubber, it broke down completely in just six hours, turning it into a soluble material with amine groups that could be used to manufacture broadly useful materials like epoxy resins.

The efficiency of this method is particularly striking when compared to traditional recycling techniques, which often require extreme temperatures or expensive catalysts. The researchers achieved their results under mild conditions (35-50°C, or 95-122°F) in aqueous media, making the process more environmentally friendly and cost-effective.

Epoxy resins are widely used in industries for adhesives, coatings, and composites. They are usually made from petroleum-based chemicals like bisphenol A and curing agents. This research shows that amine-modified poly-dienes, produced using the researchers’ method, can create epoxy materials with strength similar to commercial resins.

“In moments like this I come to appreciate the power of organic synthesis,” said Maxim Ratushnyy, a co-author of the paper and former postdoctoral scholar at UNC-Chapel Hill. “It is fascinating to see the ease with which the developed sequence of simple, yet powerful, organic transformations can take on a stubborn C — C bond and convert polybutadiene and polyisoprene-based rubbers into potentially valuable epoxy resins.”

Beyond its practical applications, this study marks a significant step toward greener recycling technologies. The researchers evaluated the environmental impact of their process using the Environmental Impact Factor (E-factor), a measure of waste generated relative to the product yield.

“E-factor is a simple but powerful metric to compare the impact of a new process to incumbents, but also to highlight process steps that can be improved as we work to transition this process out of the lab and into practice,” said Dr. Geoff Lewis, a research specialist at the University of Michigan’s Center for Sustainable Systems.

While the complete E-factor, which includes solvent use, was high, the simple E-factor, excluding solvents, was much lower, highlighting areas where the process could be further optimized for sustainability. The team is already exploring greener solvent systems and alternative reaction conditions to reduce waste generation.

“Our research represents a paradigm shift in how we approach the problem of rubber waste,” said Sydney Towell, a co-author of the study and Ph.D. candidate at UNC-Chapel Hill. “By harnessing the power of C-H amination and backbone rearrangement, this method provides a new pathway to transforming post-consumer rubber into high-value materials, reducing reliance on landfills and minimizing environmental harm.”

Obesity is considered to be a global public health concern, but experts still disagree about the precise origins and causes of rising obesity rates. One topic under debate is whether a person’s individual genetics and behaviors are more or less important than environmental factors, like socioeconomic status, in developing obesity.

In the new study, researchers estimated the impact of several factors on a person’s weight, including societal factors, like a person’s job type, as well as early life factors, like a person’s birth order, how they were delivered and whether their mother smoked or was obese. They looked specifically at whether a person was overweight, obese or severely obese at age 16 and age 42. They also looked at participants’ weight between ages 16 to 42, a range that spans the rise in obesity rates in the United Kingdom. The data came from the 1958 National Child Development Study, a long-term study that followed the lives of more than 17,000 people born in a single week in March 1958 across England, Scotland and Wales.

The analysis showed that if a mother was obese or if she smoked, her child was more likely to be obese or severely obese at each of the ages examined. The findings demonstrate that these early life factors can have a persistent effect on a person’s weight. Notably, these factors were just as powerful before and after the start of the rise in obesity rates in the UK, suggesting that the impact of individual factors, like behaviors, likely did not change during that time.

The results suggest that societal and early-life risk factors could be used to target obesity prevention programs for children and adults. The researchers also conclude that, since individual risk factors have not changed as obesity rates have risen, new studies are needed to identify societal factors that may have caused the current obesity pandemic.

The authors add: “Our research shows that the effect of maternal influences persists through to age 42 and that strikingly, those predictors were just as powerful (and prevalent) in the era before the current obesity pandemic began. This suggests that, as Geoffrey Rose pointed out, novel studies are needed of factors at the community/societal level that may have caused the current obesity pandemic, since individual-level risk factors appear not to have changed over the time period spanning the pandemic’s onset and growth.”

Peter Dempsey, PhD, professor of pediatrics-developmental biology in the CU School of Medicine, and Justin Brumbaugh, PhD, assistant professor of molecular, cellular, and developmental biology at CU Boulder, recently published a paper in the journal Nature Cell Biology showing the importance of the H3K36 methylation process in regulating plasticity and regeneration in intestinal cells.

“The intestine has an enormous ability to regenerate itself after injury, and it does this through a model of dedifferentiation,” Dempsey explains. “The cells dedifferentiate back into a type of regenerative stem cell after injury, and those stem cells eventually recover the intestine and turn back to normal cells.”

Finding the switch

Scientists have been looking for a long time for the “switch” that turns regular intestinal cells back into regenerative stem cells, Brumbaugh says. Using animal models, he, Dempsey, and the rest of their research team found that H3K36 methylation — a biochemical process that occurs within the H3 histone protein — is responsible for turning that plastic state on and off. Their research was funded by a grant from the CU Cancer Center.

“If you think about it, those cells that are normally in the intestine have to maintain their identity so they’re functional,” Brumbaugh says. “You have to be sure that they don’t flip when they’re not supposed to, because you lose their specialized function — which is also a hallmark of cancer. There has been other research on histone modifications, because epigenetics makes sense to study in this context. It makes sense that you have this form of regulation that will prevent reversion and lock in cell fate.”

Next steps

With H3K36 methylation identified as the process responsible for the switch between normal cells and regenerative cells, the researchers say the next step is to look for ways to target the process to turn it off or on as needed to treat colorectal cancer and intestinal conditions that can lead to cancer.

“H3K36 methylation seems to be directly involved in differentiating the cells, but if you take it away, the cells revert to this regenerative stem cell state,” Dempsey says. “That regenerative state is important when you have injury and repair, but there also are certain colorectal cancers that have exactly this regenerative gene signature. Chronic colitis, inflammatory bowel disease, is a repetitive injury system, and leads to a higher risk of colorectal cancer. We think we have a mechanism that could be directly applied to those types of cancers, and that’s something we want to study.”

Outside of colon cancer, the methylation process also may have implications for resistance to chemotherapy and radiation, Dempsey says.

“When the cells switch into this regenerative stem cell state, they become more resistant to certain treatments, and that’s a problem,” he says. “If you have a patient who’s not a colon cancer patient but is undergoing chemotherapy or radiation therapy, one of the side effects of those therapies is that you get destruction of intestinal stem cells. In some patients, if it’s not dosed correctly, you can actually strip the whole lining of the intestine. If you could understand how to turn that state back on, you may be able to get the cells to be more protected.”

Future applications

Brumbaugh emphasizes that the recently published research is just the first step in understanding a process that could have a significant role in treating diseases in the future.

“As stem cell biologists, we want to understand the nuts and bolts of this process, because if you do, then you can manipulate it,” he says. “You might want to manipulate it for drug testing, for disease modeling — even if it’s not something where we have a direct therapy that we’re applying to patients, if we can understand how a disease works, then that provides options and opportunities to inform therapies.

“This would be far off in the future, but creating certain cell types for transplantation therapies is something that is very exciting in the stem cell arena,” he adds. “We’re not anywhere close to that, but if you understand how to manipulate the process, you can start thinking about these types of things.”