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Promethium bound: Rare earth element’s secrets exposed
Scientists have uncovered the properties of a rare earth element that was first discovered 80 years ago at the very same laboratory, opening a new pathway for the exploration of elements critical in modern technology, from medicine to space travel.
“The whole idea was to explore this very rare element to gain new knowledge,” said Alex Ivanov, an ORNL scientist who co-led the research. “Once we realized it was discovered at this national lab and the place where we work, we felt an obligation to conduct this research to uphold the ORNL legacy.”
The ORNL-led team of scientists prepared a chemical complex of promethium, which enabled its characterization in solution for the first time. Thus, they exposed the secrets of this extremely rare lanthanide, whose atomic number is 61, in a series of meticulous experiments.
Their landmark study, published in the journal Nature, marks a significant advance in rare earth research and might rewrite chemistry textbooks.
“Because it has no stable isotopes, promethium was the last lanthanide to be discovered and has been the most difficult to study,” said ORNL’s Ilja Popovs, who co-led the research. Most rare earth elements are lanthanides, elements from 57 — lanthanum — to 71 — lutetium — on the periodic table. They have similar chemical properties but differ in size.
The other 14 lanthanides are well understood. They are metals with useful properties that make them indispensable in many modern technologies. They are workhorses of applications such as lasers, permanent magnets in wind turbines and electric vehicles, X-ray screens and even cancer-fighting medicines.
“There are thousands of publications on lanthanides’ chemistry without promethium. That was a glaring gap for all of science,” said ORNL’s Santa Jansone-Popova, who co-led the study. “Scientists have to assume most of its properties. Now we can actually measure some of them.”
The research relied on unique resources and expertise available at DOE national laboratories. Using a research reactor, hot cells and supercomputers, as well as the accumulated knowledge and skills of 18 scientists in different fields, the authors detailed the first observation of a promethium complex in solution.
The ORNL scientists bound, or chelated, radioactive promethium with special organic molecules called diglycolamide ligands. Then, using X-ray spectroscopy, they determined the properties of the complex, including the length of the promethium chemical bond with neighboring atoms — a first for science and a longstanding missing piece to the periodic table of elements.
Promethium is very rare; only about a pound occurs naturally in the Earth’s crust at any given time. Unlike other rare earth elements, only minute quantities of synthetic promethium are available because it has no stable isotopes.
For this study, the ORNL team produced the isotope promethium-147, with a half-life of 2.62 years, in sufficient quantities and at a high enough purity to study its chemical properties. ORNL is the United States’ only producer of promethium-147.
Notably, the team provided the first demonstration of a feature of lanthanide contraction in solution for the whole lanthanide series, including promethium, atomic number 61. Lanthanide contraction is a phenomenon in which elements with atomic numbers between 57 and 71 are smaller than expected. As the atomic numbers of these lanthanides increase, the radii of their ions decrease. This contraction creates distinctive chemical and electronic properties because the same charge is limited to a shrinking space. The ORNL scientists got a clear promethium signal, which enabled them to better define the shape of the trend — across the series.
“It’s really astonishing from a scientific viewpoint. I was struck once we had all the data,” said Ivanov. “The contraction of this chemical bond accelerates along this atomic series, but after promethium, it considerably slows down. This is an important landmark in understanding the chemical bonding properties of these elements and their structural changes along the periodic table.”
Many of these elements, such as those in the lanthanide and actinide series, have applications ranging from cancer diagnostics and treatment to renewable energy technologies and long-lived nuclear batteries for deep space exploration.
The achievement will, among other things, ease the difficult job of separating these valuable elements, according to Jansone-Popova. The team has long worked on separations for the whole series of lanthanides, “but promethium was the last puzzle piece. It was quite challenging,” she said. “You cannot utilize all these lanthanides as a mixture in modern advanced technologies, because first you need to separate them. This is where the contraction becomes very important; it basically allows us to separate them, which is still quite a difficult task.”
The research team used several premier DOE facilities in the project. At ORNL, promethium was synthesized at the High Flux Isotope Reactor, a DOE Office of Science user facility, and purified at the Radiochemical Engineering Development Center, a multipurpose radiochemical processing and research facility. Then, the team performed X-ray absorption spectroscopy at the National Synchrotron Light Source II, a DOE Office of Science user facility at DOE’s Brookhaven National Laboratory, specifically working at the Beamline for Materials Measurement, which is funded and operated by the National Institute of Standards and Technology.
The team also performed quantum chemical calculations and molecular dynamics simulations at the Oak Ridge Leadership Computing Facility, a DOE Office of Science user facility at ORNL, using the lab’s Summit supercomputer, the only computational resource capable of providing the necessary calculations at the time. In addition, the researchers used resources of the Compute and Data Environment for Science at ORNL. They expect future calculations to be performed on ORNL’s Frontier, the world’s most powerful supercomputer and the first exascale system, which is able to perform more than a quintillion calculations each second.
Popovs emphasized that the ORNL-led accomplishments can be attributed to teamwork. Each of the Nature paper’s 18 authors was critical to the project, he said.
The achievement sets the stage for a new era of research, the scientists said. “Anything that we would call a modern marvel of technology would include, in one shape or another, these rare earth elements,” Popovs said. “We are adding the missing link.”
Besides Popovs, Ivanov and Jansone-Popova from ORNL’s Chemical Sciences Division, the paper’s co-authors include Darren Driscoll, Subhamay Pramanik, Jeffrey Einkauf, Santanu Roy and Thomas Dyke, also of ORNL’s Chemical Sciences Division; Frankie White, Richard Mayes, Laetitia Delmau, Samantha Cary, April Miller and Sandra Davern of ORNL’s Radioisotope Science and Technology Division; Matt Silveira and Shelley VanCleve of ORNL’s Isotope Processing and Manufacturing Division; Dmytro Bykov of the National Center for Computational Sciences at ORNL; and Bruce Ravel of the National Institute of Standards and Technology.
This work was primarily co-sponsored by DOE’s Office of Science for ligand synthesis, lanthanide complexation studies, crystallization processes, spectroscopic analyses and simulation efforts. The production, purification and preparation of the promethium sample were supported by the DOE Isotope Program, managed by the Office of Science for Isotope R&D and Production. The single-crystal X-ray diffraction data collection and refinement were supported by the DOE Office of Science.
An experimental drug originally developed to treat cancer may help clear HIV from infected cells in the brain, according to a new Tulane University study.
Published in the journal Brain, this discovery marks a significant step toward eliminating HIV from hard-to-reach reservoirs where the virus evades otherwise effective treatment.
“This research is an important step in tackling brain-related issues caused by HIV, which still affect people even when they are on effective HIV medication,” said lead study author Woong-Ki Kim, PhD, associate director for research at Tulane National Primate Research Center. “By specifically targeting the infected cells in the brain, we may be able to clear the virus from these hidden areas, which has been a major challenge in HIV treatment.”
Antiretroviral therapy (ART) is an essential component of successful HIV treatment, maintaining the virus at undetectable levels in the blood and transforming HIV from a terminal illness into a manageable condition. However, ART does not completely eradicate HIV, necessitating lifelong treatment. The virus persists in “viral reservoirs” in the brain, liver, and lymph nodes, where it remains out of reach of ART.
The brain has been a particularly challenging area for treatment due to the blood-brain barrier — a protective membrane that shields it from harmful substances but also blocks treatments, allowing the virus to persist. In addition, cells in the brain known as macrophages are extremely long-lived, making them difficult to eradicate once they become infected.
Infection of macrophages is thought to contribute to neurocognitive dysfunction, experienced by nearly half of those living with HIV. Eradicating the virus from the brain is critical for comprehensive HIV treatment and could significantly improve the quality of life for those with HIV-related neurocognitive problems.
Researchers focused on macrophages, a type of white blood cell that harbors HIV in the brain. By using a small molecule inhibitor to block a receptor that increases in HIV-infected macrophages, the team successfully reduced the viral load in the brain. This approach essentially cleared the virus from brain tissue, providing a potential new treatment avenue for HIV.
The small molecule inhibitor used, BLZ945, has previously been studied for therapeutic use in amyotrophic lateral sclerosis (ALS) and brain cancer, but never before in the context of clearing HIV from the brain.
The study, which took place at the Tulane National Primate Research Center, utilized three groups to model human HIV infection and treatment: an untreated control group, and two groups treated with either a low or high dose of the small molecule inhibitor for 30 days. The high-dose treatment lead to a notable reduction in cells expressing HIV receptor sites, as well as a 95-99% decrease in viral DNA loads in the brain .
In addition to reducing viral loads, the treatment did not significantly impact microglia, the brain’s resident immune cells, which are essential for maintaining a healthy neuroimmune environment. It also did not show signs of liver toxicity at the doses tested.
The next step for the research team is to test this therapy in conjunction with ART to assess its efficacy in a combined treatment approach. This could pave the way for more comprehensive strategies to eradicate HIV from the body entirely.
This research was funded by the National Institutes of Health, including grants from the National Institute of Mental Health and the National Institute of Neurological Disorders and Stroke, and was supported with resources from the Tulane National Primate Research Center base grant of the National Institutes of Health, P51 OD011104.
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Chemical analyses find hidden elements from renaissance astronomer Tycho Brahe’s alchemy laboratory
In the Middle Ages, alchemists were notoriously secretive and didn’t share their knowledge with others. Danish Tycho Brahe was no exception. Consequently, we don’t know precisely what he did in the alchemical laboratory located beneath his combined residence and observatory, Uraniborg, on the now Swedish island of Ven.
However, during an excavation in 1988-1990, some pottery and glass shards were found in Uraniborg’s old garden. These shards were believed to originate from the basement’s alchemical laboratory. Five of these shards — four glass and one ceramic — have now undergone chemical analyses to determine which elements the original glass and ceramic containers came into contact with.
The chemical analyses were conducted by Professor Emeritus and expert in archaeometry, Kaare Lund Rasmussen from the Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark. Senior researcher and museum curator Poul Grinder-Hansen from the National Museum of Denmark oversaw the insertion of the analyses into historical context.
Enriched levels of trace elements were found on four of them, while one glass shard showed no specific enrichments. The study has been published in the journal Heritage Science.
“Most intriguing are the elements found in higher concentrations than expected — indicating enrichment and providing insight into the substances used in Tycho Brahe’s alchemical laboratory,” said Kaare Lund Rasmussen.
The enriched elements are nickel, copper, zinc, tin, antimony, tungsten, gold, mercury, and lead, and they have been found on either the inside or outside of the shards.
Most of them are not surprising for an alchemist’s laboratory. Gold and mercury were — at least among the upper echelons of society — commonly known and used against a wide range of diseases.
“But tungsten is very mysterious. Tungsten had not even been described at that time, so what should we infer from its presence on a shard from Tycho Brahe’s alchemy workshop?,” said Kaare Lund Rasmussen.
Tungsten was first described and produced in pure form more than 180 years later by the Swedish chemist Carl Wilhelm Scheele. Tungsten occurs naturally in certain minerals, and perhaps the element found its way to Tycho Brahe’s laboratory through one of these minerals. In the laboratory, the mineral might have undergone some processing that separated the tungsten, without Tycho Brahe ever realizing it.
However, there is also another possibility that Professor Kaare Lund Rasmussen emphasizes has no evidence whatsoever — but which could be plausible.
Already in the first half of the 1500s, the German mineralogist Georgius Agricola described something strange in tin ore from Saxony, which caused problems when he tried to smelt tin. Agricola called this strange substance in the tin ore “Wolfram” (German for Wolf’s froth, later renamed to tungsten in English).
“Maybe Tycho Brahe had heard about this and thus knew of tungsten’s existence. But this is not something we know or can say based on the analyses I have done. It is merely a possible theoretical explanation for why we find tungsten in the samples,” said Kaare Lund Rasmussen.
Tycho Brahe belonged to the branch of alchemists who, inspired by the German physician Paracelsus, tried to develop medicine for various diseases of the time: plague, syphilis, leprosy, fever, stomach aches, etc. But he distanced himself from the branch that tried to create gold from less valuable minerals and metals.
In line with the other medical alchemists of the time, he kept his recipes close to his chest and shared them only with a few selected individuals, such as his patron, Emperor Rudolph II, who allegedly received Tycho Brahe’s prescriptions for plague medicine.
We know that Tycho Brahe’s plague medicine was complicated to produce. It contained theriac, which was one of the standard remedies for almost everything at the time and could have up to 60 ingredients, including snake flesh and opium. It also contained copper or iron vitriol (sulphates), various oils, and herbs.
After various filtrations and distillations, the first of Brahe’s three recipes against plague was obtained. This could be made even more potent by adding tinctures of, for example, coral, sapphires, hyacinths, or potable gold.
“It may seem strange that Tycho Brahe was involved in both astronomy and alchemy, but when one understands his worldview, it makes sense. He believed that there were obvious connections between the heavenly bodies, earthly substances, and the body’s organs. Thus, the Sun, gold, and the heart were connected, and the same applied to the Moon, silver, and the brain; Jupiter, tin, and the liver; Venus, copper, and the kidneys; Saturn, lead, and the spleen; Mars, iron, and the gallbladder; and Mercury, mercury, and the lungs. Minerals and gemstones could also be linked to this system, so emeralds, for example, belonged to Mercury,” explained Poul Grinder-Hansen.
Kaare Lund Rasmussen has previously analyzed hair and bones from Tycho Brahe and found, among other elements, gold. This could indicate that Tycho Brahe himself had taken medicine that contained potable gold.
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Nitrogen emissions have a net cooling effect: But researchers warn against a climate solution
An international team of researchers has found that nitrogen emissions from fertilisers and fossil fuels have a net cooling effect on the climate. But they warn increasing atmospheric nitrogen has further damaging effects on the environment, calling for an urgent reduction in greenhouse gas emissions to halt global warming.
The paper was led by the Max Planck Institute in Germany and included authors from the University of Sydney. It comes one day after new data from the European Union’s Copernicus Climate Change Service indicated that Sunday, 21 July was the hottest day recorded in recent history.
The net cooling effect occurs in four ways:
- Short-lived nitrogen oxides produced by the combustion of fossil fuels pollute the atmosphere by forming fine suspended particles which shield sunlight, in turn cooling the climate;
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ammonia (a nitrogen and hydrogen-based compound) released into the atmosphere from the application of manure and artificial fertilisers has a similar effect;
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nitrogen applied to crops allows plants to grow more abundantly, absorbing more CO2 from the atmosphere, enabling a cooling effect;
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nitrogen oxides also play a role in the breakdown of atmospheric methane, a potent greenhouse gas.
The researchers warned that increasing atmospheric nitrogen was not a solution for combatting climate change.
“Nitrogen fertilisers pollute water and nitrogen oxides from fossil fuels pollute the air. Therefore, increasing rates of nitrogen in the atmosphere to combat climate change is not an acceptable compromise, nor is it a solution,” said Professor Federico Maggi from the University of Sydney’s School of Civil Engineering.
Sönke Zaehle from the Max Planck Institute said: “This may sound like good news, but you have to bear in mind that nitrogen emissions have many harmful effects, for example on health, biodiversity and the ozone layer. The current findings, therefore, are no reason to gloss over the harmful effects, let alone see additional nitrogen input as a means of combatting global warming.”
Elemental nitrogen, which makes up around 78 percent of the air, is climate-neutral, but other reactive nitrogen compounds can have direct or indirect effects on the global climate — sometimes warming and at other times cooling. Nitrous oxide (N2O) is an almost 300 times more potent greenhouse gas than CO2. Other forms of nitrogen stimulate the formation of ozone in the troposphere, which is a potent greenhouse gas and enhances global warming.
Professor Maggi said the research was important as it helped the team gain an understanding of the net-effect of the distribution of nitrogen emissions from agriculture.
“This work is an extraordinary example of how complex interactions at planetary scales cannot be captured with simplistic assessment tools. It shows the importance of developing mathematical models that can show the emergence of nonlinear — or unproportional — effects across soil, land, and atmosphere,” he said.
“Even if it appears counter-intuitive, reactive nitrogen introduced in the environment, mostly as agricultural fertilisers, can reduce total warming. However, this is minor compared with the reduction in greenhouse gas emissions required to keep the planet within safe and just operational boundaries.
“New generation computational tools are helping drive new learnings in climate change science, but understanding is not enough — we must act with great urgency to reduce greenhouse gas emissions.”
Gaining a holistic understanding of the impacts of nitrogen
The scientists determined the overall impact of nitrogen from human sources by first analysing the quantities of the various nitrogen compounds that end up in soil, water and air.
They then fed this data into models that depict the global nitrogen cycle and the effects on the carbon cycle, for example the stimulation of plant growth and ultimately the CO2 and methane content of the atmosphere. From the results of these simulations, they used another atmospheric chemistry model to calculate the effect of man-made nitrogen emissions on radiative forcing, that is the radiant energy that hits one square metre of the Earth’s surface per unit of time.
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