Super-Earth Atmospheres Probed At Sandia’s Z Machine (Planetary Science)

A step in the search for life elsewhere in the galaxy

The huge forces generated by the Z machine at Sandia National Laboratories are being used to replicate the gravitational pressures on so-called “super-Earths” to determine which might maintain atmospheres that could support life.

Astronomers believe that super-Earths — collections of rocks up to eight times larger than Earth — exist in the millions in our galaxy. “The question before us is whether any of these super planets are actually Earthlike, with active geological processes, atmospheres and magnetic fields,” said Sandia physicist Joshua Townsend.

The current work at Z is described in today’s Nature Communications. Researchers in Sandia’s Fundamental Science Program, working with colleagues at the Earth and Planets Laboratory of the Carnegie Institution for Science in Washington, D.C., use the forces available at Sandia’s uniquely powerful Z facility to near-instantly apply the equivalent of huge gravitational pressures to bridgmanite, also known as magnesium-silicate, the most abundant material in solid planets.

The experiments, said Townsend, gave birth to a data-supported table that shows when a planet’s interior would be solid, liquid or gaseous under various pressures, temperatures and densities, and in what predicted time spans. Only a liquid core — with its metals shifting over each other in conditions resembling that of an earthly dynamo — produces the magnetic fields that can shunt destructive solar winds and cosmic rays away from a planet’s atmosphere, allowing life to survive. This critical information about magnetic field strengths produced by the core states of different-sized super-Earths was formerly unavailable: cores are well-hidden by the bulk of the planets surrounding them, and thus not visible by remote viewing. For researchers who preferred earthly experiments rather than long-distance imaging, sufficient pressures weren’t available until Z’s capabilities were enlisted.

Yingwei Fei, the corresponding author of the current study and senior staff scientist at Carnegie’s Earth and Planets Laboratory, is known for his skill in synthesizing large-diameter bridgmanite using multiton presses with sintered diamond anvils.

“Z has provided our collaboration a unique tool that no other technique can match, for us to explore the extreme conditions of super-Earths’ interiors,” he said. “The machine’s unprecedented high-quality data have been critical for advancing our knowledge of super-Earths.”

The Magnificent Seven

Further analysis of the state of gaseous and dense materials on specific super-Earths produced a list of seven planets possibly worthy of further study: 55 Cancri e; Kepler 10b, 36b, 80e, and 93b; CoRoT-7b; and HD-219134b.

Sandia manager Christopher Seagle, who with Fei initially proposed these experiments, said, “These planets, which we found most likely to support life, were selected for further study because they have similar ratios to Earth in their iron, silicates and volatile gasses, in addition to interior temperatures conducive to maintaining magnetic fields for protection against solar wind.”

The focus on supersized, rather than small, planets came about because large gravitational pressures mean atmospheres are more likely to survive over the long haul, said Townsend.

For example, he said, “Because Mars was smaller, it had a weaker gravitational field to begin with. Then as its core quickly cooled, it lost its magnetic field and its atmosphere was subsequently stripped away.”

Z in action

For these experiments, the Z machine, with operating conditions of up to 26 million amps and hundreds of thousands of volts, creates magnetic pulses of enormous power that accelerate credit card-sized pieces of copper and aluminum called flyer-plates. These were propelled much faster than a rifle bullet into samples of bridgmanite, the Earth’s most common mineral. The near-instantaneous pressure of the forceful interaction created longitudinal and transverse sound waves in the material that reveal whether the material remains solid or changes to a liquid or gas, said Sandia researcher and paper author Chad McCoy. With these new results, researchers were supplied with solid data on which to anchor otherwise theoretical planetary models.

The technical paper concludes that the high-precision density data and unprecedently high melting temperatures achieved at the Z machine “provide benchmarks for theoretical calculations under extreme conditions.”

Concluded Fei, “Our collaboration with Sandia scientists has led to results that will encourage more academic exploration of exoplanets, whose discovery has captured the public imagination.”

“This work identifies interesting exoplanet candidates to explore further,” said Seagle. “Z shock compression plus Fei’s unusual capability to synthesize large-diameter bridgmanite lead to an opportunity to obtain data relevant to exoplanets that would not be possible anywhere else.”

The work was supported by the National Science Foundation, the Z Fundamental Science Program and a Carnegie Venture grant.

Featured image: An artist’s conception of the magnetic fields of selected super-Earths as the Z machine, pictured at bottom, mimics the gravitational conditions on other planets. Planetary magnetic fields deter cosmic rays from destroying planetary atmospheres, making life more likely to survive. (Artist image by Eric Lundin; Z photo by Randy Montoya)


Reference: Fei, Y., Seagle, C.T., Townsend, J.P. et al. Melting and density of MgSiO3 determined by shock compression of bridgmanite to 1254GPa. Nat Commun 12, 876 (2021). https://www.nature.com/articles/s41467-021-21170-y https://doi.org/10.1038/s41467-021-21170-y


Provided by Sandia National Laboratories

Combination Therapy With Radiation Shows Promise in Treating Glioblastoma (Medicine)

FINDINGS

In a study of mice, researchers at the UCLA Jonsson Comprehensive Cancer Center have identified a new approach that combines an anti-psychotic drug, a statin used to lower high cholesterol levels, and radiation to improve the overall survival in mice with glioblastoma. Glioblastoma is one of the deadliest and most difficult-to-treat brain tumors. Researchers found the triple combination extended the median survival 4-fold compared to radiation alone.

BACKGROUND

Radiation therapy is part of the standard-of-care treatment regimen for glioblastoma, often helping prolong the survival of patients. However, survival times have not improved significantly over the past two decades and attempts to improve the efficacy of radiotherapy through the use of pharmaceuticals have been hampered by the normal tissue toxicity of the drugs and the inability to penetrate the blood-brain barrier.

UCLA researchers previously reported that the first-generation dopamine receptor antagonist trifluoperazine in combination with radiation prolonged survival in mouse models of glioblastoma, but ultimately, the mice become resistant to the therapy. To help overcome this resistance, the team used quetiapine, a second-generation dopamine receptor antagonist, which not only enhanced the efficacy of radiotherapy in glioblastoma but also generated a metabolic vulnerability in the lipid homeostasis. The discovery that the combination induced the cholesterol biosynthesis pathway allowed the team to target this process with statins.

METHOD

The team tested the approach using patient-derived glioblastoma lines provided by the Biospecimen and Pathology Core of the UCLA SPORE in Brain Cancer. Quetiapine was identified in a screen of dopamine receptor antagonists for their ability to prevent phenotype conversion of non-tumorigenic glioblastoma cells into radiation-induced glioma initiating cells. Atorvastatin (Lipitor) was selected because of its known ability to cross the blood-brain-barrier.

IMPACT

While radiation alone prolongs survival of glioblastoma to some extent, attempts to enhance the treatment have not been successful. The results of the study provide evidence that using a dopamine receptor antagonist in combination with Atorvastatin and radiation may help extend the survival for people with glioblastoma. The combination therapy also includes FDA-approved drugs that can rapidly be translated into a clinical trial.

AUTHORS

The senior author Dr. Frank Pajonk, is a professor of Radiation Oncology at the David Geffen School of Medicine at UCLA and a member of the Jonsson Cancer Center. The lead author is Dr. Kruttika Bhat, a project scientist in Pajonk’s laboratory. Other authors are Mohammad Saki, Fei Cheng, Ling He, Dr. Le Zhang, Angeliki Ioannidis, David Nathanson, Jonathan Tsang, Steven Bensinger, Dr. Phioang Leia Nghiemphu, Dr. Timothy Cloughesy, Dr. Linda Liau and Dr. Harley Kornblum, all of UCLA.

JOURNAL

The study was published online in the Journal of the National Cancer Institute.

FUNDING

The work was funded in part by the National Cancer Institute and the National Institutes of Health’s Brain Specialized Programs of Research Excellence, or SPORE, at UCLA, which helps advance work in the prevention, detection and treatment of brain tumors.

Featured image: Kruttika Bhat, the study’s lead author, and Dr. Frank Pajonk, the senior author. © UCLA


Reference: Kruttika Bhat, Ph.D, Mohammad Saki, Ph.D, Fei Cheng, Ph.D, Ling He, DDS, Ph.D, Le Zhang, MD, Ph.D, Angeliki Ioannidis, David Nathanson, Ph.D, Jonathan Tsang, 2, Steven J Bensinger, V.M.D., Ph.D, Phioanh Leia Nghiemphu, MD, Timothy F Cloughesy, MD, Linda M Liau, MD, Ph.D, Harley I Kornblum, MD, Ph.D, Frank Pajonk, MD, Ph.D, Dopamine Receptor Antagonists, Radiation, and Cholesterol Biosynthesis in Mouse Models of Glioblastoma, JNCI: Journal of the National Cancer Institute, 2021;, djab018, https://doi.org/10.1093/jnci/djab018


Provided by UCLA Health

Quantum Computing Enables Simulations to Unravel Mysteries Of Magnetic Materials (Quantum)

A multi-institutional team became the first to generate accurate results from materials science simulations on a quantum computer that can be verified with neutron scattering experiments and other practical techniques.

Researchers from the Department of Energy’s Oak Ridge National Laboratory; the University of Tennessee, Knoxville; Purdue University and D-Wave Systems harnessed the power of quantum annealing, a form of quantum computing, by embedding an existing model into a quantum computer.  

Characterizing materials has long been a hallmark of classical supercomputers, which encode information using a binary system of bits that are each assigned a value of either 0 or 1. But quantum computers — in this case, D-Wave’s 2000Q – rely on qubits, which can be valued at 0, 1 or both simultaneously because of a quantum mechanical capability known as superposition.

“The underlying method behind solving materials science problems on quantum computers had already been developed, but it was all theoretical,” said Paul Kairys, a student at UT Knoxville’s Bredesen Center for Interdisciplinary Research and Graduate Education who led ORNL’s contributions to the project. “We developed new solutions to enable materials simulations on real-world quantum devices.”

This unique approach proved that quantum resources are capable of studying the magnetic structure and properties of these materials, which could lead to a better understanding of spin liquids, spin ices and other novel phases of matter useful for data storage and spintronics applications. The researchers published the results of their simulations — which matched theoretical predictions and strongly resembled experimental data — in PRX Quantum.

Eventually, the power and robustness of quantum computers could enable these systems to outperform their classical counterparts in terms of both accuracy and complexity, providing precise answers to materials science questions instead of approximations. However, quantum hardware limitations previously made such studies difficult or impossible to complete.  

To overcome these limitations, the researchers programmed various parameters into the Shastry-Sutherland Ising model. Because it shares striking similarities with the rare earth tetraborides, a class of magnetic materials, subsequent simulations using this model could provide substantial insights into the behavior of these tangible substances.

“We are encouraged that the novel quantum annealing platform can directly help us understand materials with complicated magnetic phases, even those that have multiple defects,” said co-corresponding author Arnab Banerjee, an assistant professor at Purdue. “This capability will help us make sense of real material data from a variety of neutron scattering, magnetic susceptibility and heat capacity experiments, which can be very difficult otherwise.”

Using the D-Wave chip (foreground), the team simulated the experimental signature of a sample material (background), producing results that are directly comparable to the output from real-world experiments. Credit: Paul Kairys/UT Knoxville

Magnetic materials can be described in terms of magnetic particles called spins. Each spin has a preferred orientation based on the behavior of its neighboring spins, but rare earth tetraborides are frustrated, meaning these orientations are incompatible with each other. As a result, the spins are forced to compromise on a collective configuration, leading to exotic behavior such as fractional magnetization plateaus. This peculiar behavior occurs when an applied magnetic field, which normally causes all spins to point in one direction, affects only some spins in the usual way while others point in the opposite direction instead.

Using a Monte Carlo simulation technique powered by the quantum evolution of the Ising model, the team evaluated this phenomenon in microscopic detail.

“We came up with new ways to represent the boundaries, or edges, of the material to trick the quantum computer into thinking that the material was effectively infinite, and that turned out to be crucial for correctly answering materials science questions,” said co-corresponding author Travis Humble. Humble is an ORNL researcher and deputy director of the Quantum Science Center, or QSC, a DOE Quantum Information Science Research Center established at ORNL in 2020. The individuals and institutions involved in this research are QSC members.

Quantum resources have previously simulated small molecules to examine chemical or material systems. Yet, studying magnetic materials that contain thousands of atoms is possible because of the size and versatility of D-Wave’s quantum device.

“D-Wave processors are now being used to simulate magnetic systems of practical interest, resembling real compounds. This is a big deal and takes us from the notepad to the lab,” said Andrew King, director of performance research at D-Wave.”The ultimate goal is to study phenomena that are intractable for classical computing and outside the reach of known experimental methods.”

The researchers anticipate that their novel simulations will serve as a foundation to streamline future efforts on next-generation quantum computers. In the meantime, they plan to conduct related research through the QSC, from testing different models and materials to performing experimental measurements to validate the results.

“We completed the largest simulation possible for this model on the largest quantum computer available at the time, and the results demonstrated the significant promise of using these techniques for materials science studies going forward,” Kairys said.

This work was funded by the DOE Office of Science Early Career Research Program. Access to the D-Wave 2000Q system was provided through the Quantum Computing User Program managed by the Oak Ridge Leadership Computing Facility, a DOE Office of Science user facility located at ORNL. Research performed at ORNL’s Spallation Neutron Source, also a DOE Office of Science user facility located at ORNL, was supported by the DOE Office of Science.

Featured image: The researchers embedded a programmable model into a D-Wave quantum computer chip. Credit: D-Wave


Reference: Paul Kairys, Andrew D. King, Isil Ozfidan, Kelly Boothby, Jack Raymond, Arnab Banerjee, and Travis S. Humble, “Simulating the Shastry-Sutherland Ising Model Using Quantum Annealing”, PRX Quantum 1, 020320 – Published 14 December 2020. https://journals.aps.org/prxquantum/abstract/10.1103/PRXQuantum.1.020320


Provided by Oak Ridge National Laboratory

Astronomers Offer Possible Explanation For Elusive Dark-matter-free Galaxies (Astronomy)

UC Riverside-led study finds extreme tidal mass loss in dwarf galaxies formed in a simulation

A team led by astronomers at the University of California, Riverside, has found that some dwarf galaxies may today appear to be dark-matter free even though they formed as galaxies dominated by dark matter in the past. 

Galaxies that appear to have little to no dark matter — nonluminous material thought to constitute 85% of matter in the universe — complicate astronomers’ understanding of the universe’s dark matter content. Such galaxies, which have recently been found in observations, challenge a cosmological model used by astronomers called Lambda Cold Dark Matter, or LCDM, where all galaxies are surrounded by a massive and extended dark matter halo.

Dark-matter-free galaxies are not well understood in the astronomical community. One way to study the possible formation mechanisms for these elusive galaxies — the ultradiffuse DF2 and DF4 galaxies are examples — is to find similar objects in numerical simulations and study their time evolution and the circumstances that lead to their dark matter loss.  

Laura Sales (seated, left) with her research group of former and current students, including Jessica Doppel (seated, right). (UCR/Stan Lim)

Jessica Doppel, a graduate student in the UC Riverside Department of Physics and Astronomy and the first author of research paper published in the Monthly Notices of the Royal Astronomical Society, explained that in a LCDM universe all galaxies should be dark matter dominated. 

“That’s the challenge,” she said. “Finding analogs in simulations of what observers see is significant and not guaranteed. Beginning to pin down the origins of these types of objects and their often-anomalous globular cluster populations allows us to further solidify our theoretical framework of dark matter and galaxy formation and confirms that no alternative forms of dark matter are needed. We found cold dark matter performs well.”

For the study, the researchers used cosmological and hydrodynamical simulation called Illustris, which offers a galaxy formation model that includes stellar evolution, supernova feedback, black hole growth, and mergers. The researchers found a couple of “dwarf galaxies” in clusters had similar stellar content, globular cluster numbers, and dark matter mass as DF2 and DF4. As its name suggests, a dwarf galaxy is small, comprising up to several billion stars. In contrast, the Milky Way, which has more than 20 known dwarf galaxies orbiting it, has 200 to 400 billion stars. Globular clusters are often used to estimate the dark matter content of galaxies, especially dwarfs.

The researchers used the Illustris simulation to investigate the origin of odd dwarf galaxies such as DF2 and DF4. They found simulated analogs to dark-matter-free dwarfs in the form of objects that had evolved within the galaxy clusters for a long time and lost more than 90% of their dark matter via tidal stripping — the stripping away of material by galactic tidal forces. 

“Interestingly, the same mechanism of tidal stripping is able to explain other properties of dwarfs like DF2 and DF4 — for example, the fact that they are ‘ultradiffuse’ galaxies,” said co-author Laura Sales, an associate professor of physics and astronomy at UCR and Doppel’s graduate advisor. “Our simulations suggest a combined solution to both the structure of these dwarfs and their low dark matter content. Possibly, extreme tidal mass loss in otherwise normal dwarf galaxies is how ultradiffuse objects are formed.”

In collaboration with researchers at the Max Planck Institute for Astrophysics in Germany, Sales’ group is currently working with improved simulations that feature more detailed physics and a numerical resolution about 16 times better than the Illustris simulation. 

“With these data, we will be able to extend our study to even lower-mass dwarfs, which are more abundant in the universe and expected to be more dark matter dominated at their centers, making them more challenging to explain,” Doppel said. “We will explore if tidal stripping could provide a path to deplete dwarfs of their inner dark matter content. We plan to make predictions about the dwarfs’ stellar, globular cluster, and dark matter content, which we will then compare to future observations.”

The research team has already been awarded time at the W. M. Keck Observatory to help answer some of the questions pertaining to observations of dwarfs in the Virgo cluster.

Sales and Doppel were joined in the research by Julio F. Navarro of the University of Victoria in Canada; Mario G. Abadi and Felipe Ramos-Almendares of the National University of Córdoba in Argentina; Eric W. Peng of Peking University in China; and Elisa Toloba of the University of the Pacific in California.

The study was supported by grants from NASA and the National Science Foundation.

The research paper is titled “Globular clusters as tracers of the dark matter content of dwarfs in galaxy clusters.”


Provided by University of California – Riverside

Jupiter’s Cyclones Exhibit Strange Rotations (Planetary Science)

As ever-improving resolution from the JunoCam instrument aboard NASA’s Juno spacecraft allows scientists to more closely study Jupiter, scientists have been researching an unusual trait among cyclones found near the planet’s north pole.

“JunoCam is the visible imager on the Juno payload, and has taken lots of images of the north polar cyclones,” said Candy Hansen, PSI Senior Scientist and Juno Co-Investigator who leads the JunoCam effort. “Interestingly, we see the center of the cyclones rotating in the opposite direction of the outside. This isn’t the first time we’ve seen the counter-rotation, but certainly this is the best resolution.”

JunoCam is a public outreach tool. Amateur citizen scientists participating in the JunoCam virtual imaging team and professional Scientists will continue to study Jupiter’s cyclones to figure out why, Hansen said.

Featured image: In this animated GIF, the clouds on the periphery of some of Jupiter’s polar cyclones rotate counterclockwise, while the core of the cyclones rotate clockwise. Citizen scientist Gerald Eichstädt processed the images to enhance the color and contrast. Credit: NASA/JPL-Caltech/SwRI/MSSS. Image processing: Gerald Eichstädt)


Provided by Planetary Science Institute

Water Ice Resources Identified in Martian Northern Hemisphere (Planetary Science)

Areas featuring subsurface frozen water ice that could benefit future human explorers have been identified in the northern mid-latitudes of Mars, a new paper led by Planetary Science Institute Senior Scientist Gareth A. Morgan says. 

Through the integration of orbital datasets from several NASA spacecraft – Mars Reconnaissance Orbiter, Mars Odyssey, and Mars Global Surveyor – in concert with new data-processing techniques, the Subsurface Water Ice Mapping (SWIM) on Mars project assessed the likelihood of ice by quantifying the consistency of multiple, independent data sources with the presence of ice. 

“The goal of SWIM is to provide maps of potential buried ice deposits to support the selection of human landing sites. Ice is a critical resource that has many uses, like the generation of water for human consumption, growing plants for food, and for the generation of methane fuel and breathable air. But the most important is to provide fuel for the return trip home to Earth,” said Morgan, lead author of the paper “Availability of Subsurface Water-Ice Resources in the Northern Mid-Latitudes of Mars” (https://rdcu.be/ceYax) that appears in Nature Astronomy. “Taking all the fuel you need for the round trip to Mars is basically not feasible and as a result pretty much every mission concept study from the last 30 years considers exploiting the Martian environment for fuel.” 

PSI scientists Nathaniel Putzig, Matthew Perry, Hanna Sizemore, Zachary Bain, Isaac Smith and Asmin Pathare are co-authors on the paper. 

“The good news is that Mars is an icy planet. The challenge is locating ice at a latitude that is conducive for a human landing site. Earlier studies have shown that ice buried within 3 meters of the surface should be stable in the current climate at latitudes above 50 degrees in each hemisphere, but these regions are colder and subject to long seasons of extended night. Lower latitudes are warmer, have a manageable length of night and plenty of solar radiation for power generation,” Morgan said. “In a nutshell SWIM is all about reconciling the need for ice with the need for plenty of sunshine.” 

Focusing across a significant portion of the northern hemisphere of Mars, the team’s composite ice consistency map indicates that broad regions of the mid-latitudes, equatorward of the present-day northern ice-stability zone, exhibit evidence for ice. The detected ice is buried at depths ranging from a few centimeters to about 1 kilometer. The validity of the team’s ice consistency methodology and map products was shown when the team compared their results with the locations of fresh, Ice-exposing impacts that have recently been detected by the Mars Reconnaissance Orbiter spacecraft. As new impacts are detected, the team will continue to compare them to the SWIM maps. 

“Our methodology leverages five independent remote sensing techniques: neutron spectroscopy, thermal analysis, radar surface analysis, radar subsurface compositional (dielectric) analysis, and geomorphic mapping of periglacial features. In our analysis of each of these five datasets, we attempt to isolate distinct properties of the subsurface that provide proxies for the presence – or absence – of ice,” Morgan said. “For example, we use the thermal datasets to look for regions with high subsurface thermal inertia, consistent with ice, while we apply the radar surface analysis to track evidence of ice-like low-density materials. The majority of these techniques also represent significant advancements on previous, similar methodologies.” 

PSI Senior Scientist and co-author Putzig said the paper does not select specific sites best suited for future human exploration of Mars: “Constraints imposed by the limitations of the data sets and the time available for the work meant that we were only able to evaluate ice consistency at relatively coarse resolution across the northern hemisphere. The results point to areas for further study at higher resolution with existing and future data sets that will be needed to select the most promising sites to send humans.” 

“Of course, safely delivering humans to Mars and ensuring their survival requires many other considerations beyond in situ utilization of water resources, including landing-site safety and solar and thermal specifications. Defining such site requirements is beyond the scope of the SWIM project and would be premature, given that all human Mars mission plans are still in the conceptual stage,” Morgan said. “We provide a hemispheric perspective of ice distribution to support initial landing-site studies and enable the community to explore the range of Martian terrains that host ice.” 

Funding for this project came from a subcontract (1611855) to PSI from the Caltech Jet Propulsion Laboratory, supported by NASA. 

Featured image: Two views of the northern hemisphere of Mars (orthographic projection centered on the north pole), both with a grey background of shaded relief. On the left, the light grey shading shows the northern ice stability zone, which overlaps with the purple shading of the SWIM study region. On the right, the blue-grey-red shading shows where the SWIM study found evidence for the presence (blue) or absence (red) of buried ice. The intensity of the colors reflect the degree of agreement (or consistency) exhibited by all of the data sets used by the project. © PSI


Provided by Planetary Science Institute

Chemists Identified Necessary Conditions For Successful Synthesis of Small Molecules (Chemistry)

BFU chemists identified necessary conditions for successful synthesis of small molecules

The development of the so-called small molecules is a promising field of the pharmaceutical industry. Small molecules are organic compounds with a small molecular mass. They are often based on heterocycles–carbon rings that also include atoms of nitrogen and other elements. The synthesis of small molecules is much cheaper than the development of drugs based on antibodies or other biological molecules; however, their properties are still understudied. Even the slightest modifications can change the characteristics of a small molecule and open a whole new range of its practical applications. Therefore, many research teams working in the field of chemical pharmacology improve synthesis methods to create libraries of small molecules and evaluate their biological properties. In the future, this data can be used to develop new drugs.

A team of chemists from Immanuel Kant Baltic Federal University and Saint Petersburg State University have been focusing on the synthesis of new small molecules for a long time. For example, several years ago the researchers successfully developed a method of hydrated imidazoline ring expansion (HIRE). Hydrated imidazolines are based on an imidazole heterocycle (with two nitrogen and three carbon atoms) with three more rings of different composition attached to it. The reaction created by the chemists provided for the formation of bonds with at least three bigger heterocycles, thus leading to the expansion of the initial imidazole ring. However, further studies showed that sometimes the same reaction can cause one of the tetracyclic imidazoline rings to break. In this case, the reaction product (an ethylenediamine derivative) contains no expanded heterocycles and is less useful in pharmacology because it doesn’t always produce necessary results.

The team decided to focus on the factors that promote the synthesis of expanded heterocycles. They suggested that the success of the reaction depended on the differences in the electronic properties of substituent groups. Specifically, they assumed that such differences determined the migration of the substitutes from one atom in the cycle to another. To better understand the nature of this dependency, the chemists synthesized 13 ethylenediamine derivatives. An ethylenediamine derivative is an organic substance that contains two amino groups. The derivatives were placed in alkaline solutions at different temperatures: from room temperature to 90°?.

The experiment showed that the nature of the bond between the substituent group and a nitrogen atom determines the reaction speed. If a substitute acts as an electron acceptor, i.e. pulls the electron pair that it has in common with nitrogen closer, the structure of the compound immediately changes. In some cases, it took a substituent group less than 30 seconds to migrate from one atom to another. On the contrary, the compounds with electron-donating substitutes that pushed the electron pair forward reacted slowly, and the reactions required increased temperatures. In two cases, no migration of substituent groups took place at all.

“In this study, we used relatively simple compounds as models to better understand the reaction processes in heterocyclic molecules that are in high demand in the industry. We are already using the obtained data to synthesize small molecules with expanded heterocycles from reaction by-products”, said Mikhail Krasavin, D.Sc.. in Chemistry, Research Professor at the Institute of Living Systems (BFU), and the Head of the Department of the Chemistry of Natural Products (SPbSU).

Featured image: Graphical abstract by Lavit et al.


Reference: Kseniya Lavit, Elena Reutskaya, Sergey Grintsevich, Alexander Sapegin, Mikhail Krasavin, Zooming in on the hydrated imidazoline ring expansion: Factors influencing the rate of N →N′ aroyl migration in N-aroyl-N-(hetero)aryl ethylenediamines, Tetrahedron Letters, Volume 61, Issue 42, 2020, 152423, ISSN 0040-4039, https://doi.org/10.1016/j.tetlet.2020.152423. (https://www.sciencedirect.com/science/article/pii/S0040403920309011)


Provided by IKBFU

Early Study Points To Potential Therapeutic Avenue For a Pair of Rare Pediatric Diseases (Medicine)

Scientists have devised a new approach for detecting and potentially heading off the effects of two rare pediatric diseases before birth.

The study, performed in mouse models of the diseases and published today in Cell Reports, represents an important step toward much-needed early interventions for Beckwith-Wiedemann syndrome and Silver-Russell syndrome.

Both diseases result in growth-related symptoms in children and often lead to additional problems later in life, such as increased cancer risk from Beckwith-Wiedemann syndrome and increased metabolic disease risk from Silver-Russell syndrome.

Piroska Szabó, Ph.D. © VAI

“Both of these diseases have lifelong consequences,” said Piroska Szabó, Ph.D., an associate professor at Van Andel Institute and the study’s corresponding author. “Our findings provide a critical foundation for additional studies that we hope will translate into new, life-changing prenatal detection and treatment methods. Our goal is for children to be born healthy.”

Fetuses with Beckwith-Wiedemann syndrome experience too much growth during development while fetuses with Silver-Russell experience too little growth. Likewise, about one-third of Beckwith-Wiedemann cases and two-thirds of Silver-Russell cases may arise from having either too much or too little of a protein called IGF2, which plays a critical role in fetal growth and development.

Using models of the diseases, Szabó and colleagues were able to detect and measure IGF2 in amniotic fluid and correlate variations in IGF2 levels with Beckwith-Wiedemann and Silver-Russell syndromes, opening up new opportunities for early detection.

The researchers also were able to correct IGF2 levels in a genetic experiment, essentially reversing the fetal growth problems associated with both disease models. They found that treatment before birth with an FDA-approved cancer medication that targets IGF2 signaling normalized fetal growth in the Beckwith-Wiedemann model.

More research and clinical studies are needed before it is known whether the findings hold true in humans, Szabó cautioned. She hopes to find a clinical collaborator with whom to partner for future studies.

“There’s a big gap between an experiment in the lab and implementation in the clinic,” Szabó said. “However, our results are a vital step toward finding ways to identify and treat these syndromes before birth.”

Authors include Ji Liao, Ph.D., Tie-Bo Zeng, Ph.D., and Nicholas Pierce of VAI; and Diana A. Tran, Purnima Singh, M.S., Ph.D., MB, MSPH, and Jeffrey R. Mann, Ph.D., of City of Hope.

This work was supported by Van Andel Institute and the National Institute of General Medical Sciences of the National Institutes of Health under award no. R01GM064378 (Szabó). The content is solely the responsibility of the authors and does not necessarily represent the official views of the granting organization.


Reference: Ji Liao, Tie-Bo Zeng, Nicholas Pierce et al., “Prenatal correction of IGF2 to rescue the growth phenotypes in mouse models of Beckwith-Wiedemann and Silver-Russell syndromes”, Cell Reports, 34(6), 2021. DOI: https://doi.org/10.1016/j.celrep.2021.108729


Provided by Van Andel Institute


ABOUT VAN ANDEL INSTITUTE

Van Andel Institute (VAI) is committed to improving the health and enhancing the lives of current and future generations through cutting edge biomedical research and innovative educational offerings. Established in Grand Rapids, Michigan, in 1996 by the Van Andel family, VAI is now home to more than 400 scientists, educators and support staff, who work with a growing number of national and international collaborators to foster discovery. The Institute’s scientists study the origins of cancer, Parkinson’s and other diseases and translate their findings into breakthrough prevention and treatment strategies. Our educators develop inquiry-based approaches for K–12 education to help students and teachers prepare the next generation of problem-solvers, while our Graduate School offers a rigorous, research-intensive Ph.D. program in molecular and cellular biology. Learn more at vai.org.

THz Spectroscopy Tracks Electron Solvation in Photoionized Water (Physics)

Photoionization of water involves the migration and solvation of electrons, with many transient and highly active intermediates. The process results in a large blue shift in the absorption spectrum, from the THz or gigahertz region to the visible range. While the behavior of low-density quasifree electrons excited by small pump power density has been investigated extensively, we still know little about the transient evolution of photoexcited plasma in liquid water. Valuable insights were recently provided by an international research team in a study published in Advanced Photonics.

According to Liangliang Zhang, physics professor at Capital Normal University in Beijing and one of the senior authors on the study, the physical mechanism of plasma evolution on the ultrafast sub-picosecond scale in liquid water is considered as an extension of the theory of gas plasma. But laser-induced plasma in liquid water is accompanied by more complex and stronger nonlinear effects than those in gas, since water has a higher nonlinear coefficient, a lower excitation threshold, and a higher electron density. These differences promise the possibility of unlocking new technologies and applications, encouraging researchers to explore the potential physical mechanism of photoexcited plasma in liquid water.

Water solvent electrons?

Zhang’s team induced plasma in a stable free-flowing water film by using 1650-nm femtosecond laser pulses. They focused these intense terahertz (THz) pulses to probe at the sub-picosecond scale the temporal evolution of quasifree electrons of laser-induced plasma in water. THz wave absorption with a unique two-step decay characteristic in the time domain signature was demonstrated, indicating the significance of electron solvation in water.

(a) Diagram of the experimental system. (b) THz time-domain waveforms in liquid water without optical pump (black line) and under the maximal absorption caused by the formed plasma (red line). (c) Transient evolution curve of THz wave absorption by plasma in water with the pump energy of 90 μJ/pulse. (d) Black points indicate the peak quasi-free electron density with different pump pulse energies. The orange points show the relationship between the solvation ratio and the pump pulse energy at the equilibrium state. © Spie

Using the Drude model combined with the multilevel intermediate model and particle-in-a-box model, the researchers simulated and analyzed the quasifree electrons to obtain key information such as the frequency-domain absorption characteristics and solvation ratio. Remarkably, as the quasifree electron density increased, the traps related to the bound states appeared to saturate, resulting in a large number of quasifree electrons that cannot be completely solvated. According to Zhang, “This work provides insights on the fundamental aspects of the charge transport process in water and lays a foundation for further understanding of the physicochemical properties and transient evolution of femtosecond-laser-pulse-excited plasma in water.”

Featured image: THz spectroscopy probes photoexcited plasma in water, from Tan et al., doi 10.1117/1.AP.3.1.015002

Read the original research article by Yong Tan et al., “Transient evolution of quasi-free electrons of plasma in liquid water revealed by optical-pump terahertz-probe spectroscopy,” Adv. Photon. 3(1), 015002 (2021), doi 10.1117/1.AP.3.1.015002


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