The study of radioactive decay is fundamental to understanding the properties of atomic nuclei. When these unstable nuclei lose energy through radiation, they undergo various decay modes. Researching nuclear decay patterns provides crucial insights into the structure of nuclei located beyond the stability valley – an area containing stable nuclei on the nuclear chart.

Physicists from the Institute of Modern Physics (IMP) of the Chinese Academy of Sciences (CAS), along with their collaborators, have published a groundbreaking study in Physical Review Letters. On July 10th, they reported the first observation and spectroscopy of aluminium-20, an unprecedentedly unstable isotope that decays via the rare three-proton emission process.

According to Associate Professor Xiaodong Xu from IMP, who led the research team, “Aluminium-20 holds the distinction as the lightest aluminium isotope discovered thus far. Situated beyond the proton drip line, it boasts seven fewer neutrons than its stable counterpart.” The researchers employed an in-flight decay technique at the Fragment Separator of the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany to measure angular correlations between aluminium-20’s decay products and uncover this previously unknown nucleus.

By conducting a detailed analysis of these angular correlations, the researchers discovered that the aluminium-20 ground state initially undergoes proton emission to reach an intermediate magnesium-19 state. Subsequently, magnesium-19 decays via simultaneous two-proton emission. This scenario presents a unique case where the one-proton decay daughter nucleus (magnesium-19) itself is a radioactive nucleus capable of emitting two protons.

The study also revealed that aluminium-20’s ground-state decay energy significantly differs from predictions based on isospin symmetry, hinting at possible isospin symmetry breaking in aluminium-20 and its mirror partner neon-20. Theoretical calculations support this finding by predicting spin-parity discrepancies between aluminium-20 and neon-20 ground states.

This research contributes to our understanding of proton-emission phenomena, shedding light on the structure and decay processes involved in nuclei located beyond the stability valley. To date, scientists have identified over 3,300 nuclides; however, only around 300 are stable and occur naturally, with the remainder being unstable and undergoing radioactive decay.

The discovery of exotic decay modes, such as single-proton radioactivity (observed in the 1970s), two-proton radioactivity (identified after entering the 21st century), and even rarer phenomena like three-, four-, and five-proton emission, has greatly expanded our knowledge of nuclear physics. This research was made possible through a collaborative effort involving institutions such as IMP, GSI, Fudan University, and more than a dozen others.

The work received support from the National Key R&D Program of China, the CAS President’s International Fellowship Initiative, and the National Natural Science Foundation of China, among other funders.

Chemists have made a groundbreaking breakthrough in developing a novel method to generate highly useful chemical building blocks by harnessing metal carbenes. This achievement is expected to revolutionize the synthesis of life-saving drugs and materials development.

Typically used in chemical reactions essential for drug synthesis, carbenes are short-lived, highly reactive carbon atoms. However, creating these carbenes has been a challenging task due to limited methods and hazardous procedures.

Researchers at The Ohio State University have now developed an approach that makes producing metal carbenes much easier and safer. According to David Nagib, co-author of the study and distinguished professor in arts and sciences, “Our goal all along was to determine if we could come up with new methods of accessing carbenes that others hadn’t found before.”

The team’s innovative method uses iron as a metal catalyst and combines it with chlorine-based molecules that easily generate free radicals. This combination works to form the carbene of their choice, including many that had never been made before.

These three-sided molecular fragments, known as cyclopropanes, are vital to the synthesis of medicines and agrichemicals due to their small size and unusual energy. The researchers’ work was inspired by looking for the best ways to create these shape, which is one of the most common found in medicines.

“Our lab is obsessed with trying to get the best methods for making cyclopropanes out there as soon as possible,” said Nagib. “We have the eye on the prize of inventing better tools to make better medicines, and along the way, we’ve solved a huge problem in the carbene world.”

The study was recently published in Science, and the team’s discovery is expected to become extremely impactful. By accessing a new way of creating and classifying carbenes, scientists can simplify and improve the current wasteful, multistep process of producing them.

For consumers, this method suggests that future drugs developed by this technology may be cheaper, more potent, faster-acting, and longer-lasting. The work could prevent shortages of important medicines like antibiotics and antidepressants, as well as drugs that treat heart disease, COVID, and HIV infections, said Nagib.

Additionally, the team would like to ensure that their transformational organic chemistry tool is accessible to both big and small research labs and drug manufacturers around the world. One way to guarantee this is by continuing to improve the current technique, said Nagib.

“Our team at Ohio State came together in the coolest, most collaborative way to develop this tool,” he said. “So we’re going to continue racing to show how many different types of catalysts it could work on and make all kinds of challenging and valuable molecules.”

The study published in Royal Society Open Science presents a groundbreaking approach to understanding the mechanical properties of crystals. Researchers from The University of Osaka have successfully used differential geometry to provide a unified description for the mechanics of crystals and their defects. This breakthrough has significant implications for the development of new materials with enhanced strength and durability.

Crystals, renowned for their beauty and elegance, often appear perfect on the outside. However, upon closer examination, they contain small defects in their structure – missing atoms or extra bonds. These imperfections have important mechanical consequences, as they can serve as starting points for fractures or even be used to strengthen materials. Understanding defects and their phenomena is crucial for researchers.

The study’s lead author, Shunsuke Kobayashi, notes that “defects come in many forms.” For instance, there are dislocations associated with the breaking of translational symmetry and disclinations associated with the breaking of rotational symmetry. Capturing all these types of defects within a single mathematical theory is not straightforward.

Previous models have struggled to reconcile the differences between dislocations and disclinations, indicating that modifications to the theory are needed. The research team found that new mathematical tools using differential geometry proved to be exactly what was required to address these issues.

Differential geometry provides an elegant framework for describing these complex phenomena. Simple mathematical operations can capture these effects, allowing researchers to focus on the similarities between seemingly disparate defects. Using the formalism of Riemann-Cartan manifolds, the team elegantly encapsulated the topological properties of defects and rigorously proved the relationship between dislocations and disclinations.

In addition, they derived analytical expressions for the stress fields caused by these defects. The research team hopes that their geometric approach to describing the mechanics of crystals will eventually inspire scientists and engineers to design materials with specific properties by taking advantage of defects, such as the strengthening of materials seen with disclinations. This breakthrough is yet another example of how beauty in mathematics can help us understand beauty in nature.