Category: Cornell High Energy Synchrotron Source (CHESS)

How CHESS Helped Reveal Hidden Differences in Our DNA Packaging

How CHESS Helped Reveal Hidden Differences in Our DNA Packaging

How does pressure affect the molecules that organize our DNA?

Using high-pressure X-ray scattering at CHESS, researchers revealed surprising differences between conventional and centromeric nucleosomes. This research sheds light on how our genetic material withstands extreme conditions and stays resilient under stress.

A nucleosome is the basic repeating subunit of chromatin packaged inside the cell’s nucleus. In humans, about six feet of DNA must be packaged into a nucleus with a diameter less than a human hair, and nucleosomes play a key role in that process.

What happens when you squeeze DNA? Can pressure reveal something about how our genetic material is packed, protected, and accessed?

Dr. Kushol Gupta, a structural biologist at the University of Pennsylvania, is pursuing this question and found that turning up the pressure might be one of the best ways to peek into how life organizes itself at the atomic scale.

In a new study published in Chromosome Research, Gupta and collaborators used high-pressure small-angle X-ray scattering (HP-SAXS) at CHESS to explore how different parts of our DNA, particularly nucleosomes, respond to extreme physical stress. 

Experiments were carried out at the NSF and NIH-funded beamline ID7A1 at CHESS using a custom-built hydrostatic pressure cell that was designed by Durgesh Rai and Richard Gillilan and is capable of reaching upwards of 400 megapascals (MPa), i.e., roughly 4,000 times atmospheric pressure, or four times the pressure at the bottom of the Mariana Trench.

Cracking Open the Chromatin Code

Inside each cell, DNA is tightly packed into a material called chromatin, which is made up of DNA and proteins that help organize the genome and control gene activity.

Nucleosomes are the molecular “reels” that organize our DNA, helping package nearly six feet of genetic material into each tiny cell. The canonical nucleosome consists of DNA coiled around a core of histone H3 proteins. But not all nucleosomes are created equal. Some nucleosomes are found at the centromere, the region of a chromosome that plays a key role in cell division, and contain a specialized protein called CENP-A, a variant of histone H3.

“Centromeric nucleosomes are unique in both their composition and their function,” said Gupta. “But understanding what makes them physically different from conventional nucleosomes has been difficult, especially in realistic, solution-based environments.”

Gupta, a crystallographer by training, specializes in using scattering techniques to study biological structures, and wanted to go beyond static snapshots of these particles. He wanted to see how they behave, flex, and respond under pressure.

What they found was quite revealing.

Read more on the CHESS website

Image: A nucleosome is the basic repeating subunit of chromatin packaged inside the cell’s nucleus. In humans, about six feet of DNA must be packaged into a nucleus with a diameter less than a human hair, and nucleosomes play a key role in that process.

Credit: National Human Genome Research Institute

Unlocking the Mysteries of Life Under Pressure

Unlocking the Mysteries of Life Under Pressure

As scientists continue to discover new niches for extreme life, the biological relevance of hydrostatic pressure is becoming much more widely understood and appreciated. The unusual adaptations of organisms thriving under these conditions promise to be a rich source of new insights, provided structural information can be obtained at the molecular level.

CHESS is at the forefront of this research – enabling scientists to study samples under high pressure, revealing how biomolecules and cellular structures behave in extreme environments.

The deep sea encompasses more than 90% of Earth’s habitable volume, characterized by low temperatures and high pressures, with pressure increasing by about 1 bar per 10 meters depth. This extreme environment is home to unique organisms with remarkable adaptations. The biological relevance of hydrostatic pressure is becoming much more widely understood and appreciated as discoveries of new niches for extreme life continue to emerge.

University of California San Diego Assistant Professor of Chemistry and Biochemistry Itay Budin teamed up with researchers from around the country to study the cell membranes of ctenophores (“comb jellies”) and found they had unique lipid structures that allow them to live under intense pressure. Their work appears in Science.

In addition to biological applications, hydrostatic pressure is a useful biophysical tool that can perturb systems in ways directly connected to the presence of atomic-level voids, cavities, and other volumetric properties. Under pressure, individual molecular complexes can dissociate, and monomers can unfold; transitions can occur in lipid mesophases, and liquid phases can dissolve and re-form.

Read more on CHESS website

Image: A collage of comb jelly species arranged in order of depth. The shallowest one (top left) lives near the surface; the deepest one (bottom) attaches itself to seafloor structures 2.5 miles/4 km deep. The study was inspired by comparing the chemical composition of shallow and deep comb jellies.

 Credit: Jacob Winnikoff

Light-twisting materials created from nano semiconductors

Light-twisting materials created from nano semiconductors

Cornell scientists have developed a novel technique to transform symmetrical semiconductor particles into intricately twisted, spiral structures – or “chiral” materials – producing films with extraordinary light-bending properties.

The discovery, detailed in a paper publishing Jan. 31 in the journal Science, could revolutionize technologies that rely on controlling light polarization, such as displays, sensors and optical communications devices.

Chiral materials are special because they can twist light. One way to create them is through exciton-coupling, where light excites nanomaterials to form excitons that interact and share energy with each other. Historically, exciton-coupled chiral materials were made from organic, carbon-based molecules. Creating them from inorganic semiconductors, prized for their stability and tunable optical properties, has proven exceptionally challenging due to the precise control needed over nanomaterial interactions.

Scientists from the lab of Richard D. Robinson, associate professor of materials science and engineering in Cornell Engineering and senior author of the study, overcame this challenge by employing “magic-sized clusters” made from cadmium-based semiconductor compounds. Magic-sized clusters are unique nanoparticles because they are identical copies of each other, existing only in discrete sizes, unlike many nanoparticles that can vary continuously in size. Previous research by the Robinson Group reported that when the nanoclusters were processed into thin films, they demonstrated circular dichroism, a key signature of chirality.

“Circular dichroism means the material absorbs left-handed and right-handed circularly polarized light differently, like how screw threads dictate which way something twists,” Robinson explained. “We realized that by carefully controlling the film’s drying geometry, we could control its structure and its chirality. We saw this as an opportunity to bring a property usually found in organic materials into the inorganic world.”

The researchers used meniscus-guided evaporation to twist linear nanocluster assemblies into helical shapes, forming homochiral domains several square millimeters in size. These films exhibit an exceptionally large light-matter response, surpassing previously reported record values for inorganic semiconductor materials by nearly two orders of magnitude.

“I’m excited about the versatility of the method, which works with different nanocluster compositions, allowing us to tailor the films to interact with light from the ultraviolet to the infrared,” said Thomas Ugras, a doctoral student in the field of applied and engineering physics who led the research. “The assembly technique imbues not only chirality but also linear alignment onto nanocluster fibers as they deposit, making the films sensitive to both circularly and linearly polarized light, enhancing their functionality as metamaterial-like optical sensors.”

This discovery could revolutionize technologies that rely on controlling light polarization, and lead to new innovations, such as holographic 3D displays, room-temperature quantum computing, ultra-low-power devices, or medical diagnostics that analyze blood glucose levels non-invasively. The findings also provide insights into the formation of natural chiral structures, such as DNA, which could inform future research in biology and nanotechnology.

Read more on CHESS website

MSN-C matures a technique to map residual strain in complex-shaped, as-manufactured parts

MSN-C matures a technique to map residual strain in complex-shaped, as-manufactured parts

MSN-C has successfully showcased a new, comprehensive workflow to map residual strain on a challenging set of near-net-shape additive manufactured parts. This achievement signals MSN-C’s readiness to conduct such measurements for the broad community of academic, government and industry scientists and engineers seeking to understand and control failure in high performance structural components. Routine access to this kind of information now available at MSN-C holds great potential value for both DoD and commercial manufacturing. 

Background

Residual stress refers to internal stresses that remain within a solid object in the absence of external applied loads. In structural components, especially metallic parts that support static or cyclic loads, residual stresses can significantly impact mechanical performance. Whether the presence of residual stress is beneficial or detrimental to mechanical response depends on details such as the sign, magnitude, and direction of residual stress, location and distribution throughout the part, and application conditions of how the part is loaded in service. Residual stress is also an important consideration during the manufacturing process; this is particularly true for developing additive manufacturing processes such as laser powder bed fusion, where generation of significant residual stresses during the build process can lead to distortions in part geometry or total build failure. In general, residual stress is a key consideration in mechanical design and engineering.

Because of the critical link to performance, the aerospace industry is deeply concerned with residual stress, and invests heavily in ways to model, measure, and engineer the presence or absence of residual stress for the vast array of components that comprise products like engines and aircraft. Despite significant innovation in these areas, however, a persistent challenge remains in developing a best practice for quantitative measurement of residual stress. 

Stress cannot be measured directly, but rather can be calculated using Hooke’s Law from measurements of elastic strain when combined with knowledge of the elastic properties of the material. X-ray diffraction provides a means of directly measuring the elastic strains of a crystal by comparing the spacing of crystallographic lattice planes to those of an unstrained reference. Performing such measurements at a high energy synchrotron facility such as CHESS enables orders-of-magnitude greater efficiency and fidelity of elastic strain measurements, representing a great opportunity for addressing residual stress challenges. 

MSN-C was founded in large part to develop and devote synchrotron-based methods to address challenges facing advanced manufacturing, including determination of residual strain. 

Read more on CHESS website

Image: Five additive manufacturing samples mounted simultaneously with a calibration sample. A red dot from the laser that is used to measure the specimen surface is visible on the printed fan blade.

New Oxygen-Reduction Electrocatalysts for Alkaline Fuel Cells

New Oxygen-Reduction Electrocatalysts for Alkaline Fuel Cells

Hydrogen fuel cells are among the most promising next-generation power sources for future automotive transportation. Developing efficient, durable, and low-cost electrocatalysts to accelerate the sluggish oxygen reduction reaction (ORR) is urgently needed to advance fuel cell technologies.Now, in a new paper appearing in the Journal of the American Chemical Society, a team of researchers from Cornell and the University of Wisconsin report new catalysts which exhibit superior ORR activity and robust stability. The team has characterized metal–organic framework-derived nonprecious dual metal single-atom catalysts (SACs), consisting of Co–N4 and Zn–N4 local structures. Their remarkable performance was validated under realistic fuel cell working conditions, achieving a record-high peak power density of ∼1 W cm–2 among the reported SACs for alkaline fuel cells. Operando X-ray absorption spectroscopy studies at the PIPOXS beamline at CHEXS revealed that the Co atom in the Co–N4 structure is the main catalytically active center. This work provides a comprehensive mechanistic understanding of the active sites in the Zn/Co–N–C catalysts and will pave the way for the future design and advancement of high-performance single-site electrocatalysts for fuel cells and other energy applications.

Read more on CHESS website

Image: Isolated Zinc and Cobalt atoms on a metal-organic-framework scaffold occupy local environments which are coordinated by 4 Nitrogen atoms. Using x-ray spectroscopy inside operating hydrogen fuel cells, the Cornell/Wisconsin team (with then-PhD-student Weixuan Xu as first author) were able to directly observe that specifically the Co-N4 sites were responsible for highly efficient catalysis of the oxygen reduction reaction. As oxygen bonds to a Co-N4 site, the Co XANES edge shifts to higher energy, providing a clear fingerprint for the reaction mechanism.

Unlocking the Mysteries of Life Under Pressure

Unlocking the Mysteries of Life Under Pressure

As scientists continue to discover new niches for extreme life, the biological relevance of hydrostatic pressure is becoming much more widely understood and appreciated. The unusual adaptations of organisms thriving under these conditions promise to be a rich source of new insights, provided structural information can be obtained at the molecular level.

CHESS is at the forefront of this research – enabling scientists to study samples under high pressure, revealing how biomolecules and cellular structures behave in extreme environments.

The deep sea encompasses more than 90% of Earth’s habitable volume, characterized by low temperatures and high pressures, with pressure increasing by about 1 bar per 10 meters depth. This extreme environment is home to unique organisms with remarkable adaptations. The biological relevance of hydrostatic pressure is becoming much more widely understood and appreciated as discoveries of new niches for extreme life continue to emerge.

University of California San Diego Assistant Professor of Chemistry and Biochemistry Itay Budin teamed up with researchers from around the country to study the cell membranes of ctenophores (“comb jellies”) and found they had unique lipid structures that allow them to live under intense pressure. Their work appears in Science.

Read more on CHESS website

Image: A collage of comb jelly species arranged in order of depth. The shallowest one (top left) lives near the surface; the deepest one (bottom) attaches itself to seafloor structures 2.5 miles/4 km deep. The study was inspired by comparing the chemical composition of shallow and deep comb jellies.

 Credit: Jacob Winnikoff

CHESS receives $20M from NSF for new X-ray beamline

CHESS receives $20M from NSF for new X-ray beamline

The U.S. National Science Foundation has awarded the Cornell High Energy Synchrotron Source (CHESS) nearly $20 million to build a new precision X-ray beamline for research on biological and environmental systems.

The X-rays for Life, Environmental, Agriculture and Plant sciences (XLEAP) beamline will be an important resource for the U.S. scientific community, filling a need for X-ray fluorescence-based technology supporting biological and biogeochemical research.

“We are thrilled to receive this funding from the NSF for the XLEAP beamline,” said Joel Brock, CHESS director. “This investment is not only a significant step forward for CHESS but also highlights the importance of advancing precision X-ray studies in the realm of agriculture, biology, and environmental sciences.

“XLEAP will be a game-changer, allowing researchers to explore live soil and plant systems under controlled growth conditions, paving the way for groundbreaking discoveries.”

Scientists at CHESS hope to develop a better understanding of the carbon cycle, which could lead to the development of safer and more nutritious crops.

“This $20 million federal investment will supercharge Cornell’s cutting-edge CHESS Lab and bring us to the next frontier of understanding the elemental and microscopic details of organisms.” said Senator Schumer. “When CHESS faced major cuts in federal support 10 years ago, I fought tooth and nail to ensure its pioneering research and hundreds of good-paying jobs would remain here in Upstate New York, and now this latest boost in federal investment shows that CHESS is top of its class not just in America, but the world.

“The addition of the new XLEAP beamline could not be in better hands at CHESS,” Schumer said, “and is just the latest in showing how Ithaca is leading the way in making Upstate NY a global leader in research and technology.”

“XLEAP is a perfect example of enabling technology that allows for fundamental research that creates knowledge that can be put to use addressing societal challenges,” said Susan Marqusee, NSF assistant director for biological sciences. “NSF is proud to support this key infrastructure that holds the potential to help advance the bioeconomy, build a resilient planet, and more.”

“X-rays are a really powerful tool for visualizing the chemical composition of complex structures like soils and plants,” said Louisa Smieska, XLEAP beamline scientist. “XLEAP is special because it will allow researchers to study live soil and plant systems in controlled growth conditions, not only in a steady state, but when we expose those systems to changes, such as the nutrients available, the amount of carbon dioxide in the air, or adding nanoparticles, fungi, bacteria, or microplastics.”

By combining state-of-the-art technology and expertise at CHESS with other world-class research facilities at Cornell, XLEAP will aid in the development of tools suited to answer questions of fundamental biology, biomedical sciences, geology, environmental science, materials science, and cultural heritage.

Read more on the CHESS website

Image: School of Integrate Plant Science (SIPS) research associate Ju-Chen Chia and XLEAP Beamline Scientist Louisa Smieska examine plants in the SIPS growth chambers

Democratizing data-driven scientific discovery

Democratizing data-driven scientific discovery

In a groundbreaking initiative aimed at democratizing data-driven scientific discovery, the National Science Data Fabric (NSDF) and the Cornell High Energy Synchrotron Source (CHESS) have collaborated in establishing a trans-disciplinary approach for integrated data delivery and access to research data visualization, shared storage, networking, and computing resources.

The NSDF pilot, a collaborative effort connecting an open network of institutions, offers a modular and easily accessible data delivery environment. Configurable for individual and shared scientific use, this environment operates at the best economies of scale, filling a crucial gap in the current computational infrastructure. Funded by the National Science Foundation, the pilot embraces equity in access to data and cyberinfrastructure resources, benefiting a wide range of scientific domains. The active involvement of Historically Black Colleges, the Minority Serving Cyberinfrastructure Consortium, and Hispanic Serving Institutions informs the NSDF’s development, advancing inclusivity in data-driven science.

The vision of the NSDF is to establish a globally connected infrastructure that transcends the limitations of extreme data. The mission is clear: to democratize access to large-scale scientific data by developing scalable solutions for data storage, movement, and processing – deployable on various platforms, including commodity hardware and cloud computing.

Werner Sun, Director of CHESS IT, shed light on this transformative collaboration, “CHESS is collaborating with NSDF to develop a set of applications for data-intensive science, focusing on real-time visualization of large three-dimensional datasets. The eventual goal is for CHESS to be part of this national cyberinfrastructure, facilitating the transport of CHESS data across the country for analysis by other researchers.”

Commissioned in November 2023, the NSDF Entry Point at CHESS serves as a customized server connecting CHESS to NSDF storage, compute, and networking components. This Entry Point empowers CHESS users with NSDF dashboards for easy-to-use and scalable tools, offering a complete software stack for accessing data services while simplifying the intricacies of high-speed data movements.

A pivotal development in this collaboration is the implementation of the NSDF dashboard built on OpenViSUS technology, a data-intensive analytics and visualization platform that streamlines data collection, improves data quality, and increases scientific productivity. By facilitating real-time visualization of large three-dimensional datasets collected at CHESS, OpenViSUS enables experimenters to perform preliminary analysis at the beamline, with data visualized in as little as 20 minutes. NSDF Dashboards integrated into the system provide interactive data quality monitoring, allowing researchers to identify and address issues during data collection. These dashboards can be accessed onsite or offsite, allowing remote users to monitor experimental progress from their home institutions.

Read more on CHESS website

Image: Screenshot of the NSDF dashboard showing two linked views of x-ray scattering intensity in a single 3D volume

CHESS celebrates construction milestone with Wilson West open house

CHESS celebrates construction milestone with Wilson West open house

On Wednesday, November 15, CHESS had an open house for members of the Cornell community in the new Wilson West expansion project. The project recently received its temporary certificate of occupancy, which marks a milestone in the construction project.

Wilson West houses a new large experimental hall to accommodate the upcoming High Magnetic Field X-ray Beamline. Guests were invited to tour the new building, including future beamline caves, server rooms, electronics and vacuum labs, sample preparation rooms, and an ADA-accessible chemistry room.

The new milestone marks a point in the project when efforts will begin to move from building construction to installing highly specialized experimental equipment.

Read more on CHESS website

Image: The high bay area of the new Wilson West building

Lake source cooling brings sustainability, precision to synchrotron

Lake source cooling brings sustainability, precision to synchrotron

The science of flinging around X-rays, electrons and positron beams to study the secret life of matter requires a tremendous amount of energy. It also requires a constant supply of cool water to keep the technology functioning consistently and prevent it from overheating.

For decades, the Wilson Laboratory, which houses the Cornell High Energy Synchrotron Source (CHESS), has relied on four immense cooling towers that evaporate 10,000 gallons of water daily to reduce the temperature of the nearly 650 electromagnets – some roughly twice the size of a human being – that line a half-mile-long ring buried 40 feet below a scenic swath of east campus.

Those towers are now obsolete because the lab has tapped into the university’s Lake Source Cooling (LSC) system, which draws cold water from the depths of Cayuga Lake to remove heat from the district chilled water loop that cools the majority of Cornell facilities. For Wilson Lab, this approach is not only more efficient and sustainable – it will bring greater precision to its experiments. LSC will also, for the first time, enable CHESS to operate year-round.

Read more on the CHESS website

Image: Leila Aboharb, mechanical systems engineer at Wilson Lab, says Lake Source Cooling is a much more reliable system than the four cooling towers that were installed in 1989.

Credit: Noël Heaney/Cornell University

Machine learning enhances X-ray imaging of nanotextures

Machine learning enhances X-ray imaging of nanotextures

Using a combination of high-powered X-rays, phase-retrieval algorithms and machine learning, Cornell researchers revealed the intricate nanotextures in thin-film materials, offering scientists a new, streamlined approach to analyzing potential candidates for quantum computing and microelectronics, among other applications.

Scientists are especially interested in nanotextures that are distributed non-uniformly throughout a thin film because they can give the material novel properties. The most effective way to study the nanotextures is to visualize them directly, a challenge that typically requires complex electron microscopy and does not preserve the sample.

The new imaging technique detailed July 6 in the Proceedings of the National Academy of Sciences overcomes these challenges by using phase retrieval and machine learning to invert conventionally-collected X-ray diffraction data – such as that produced at the Cornell High Energy Synchrotron Source, where data for the study was collected – into real-space visualization of the material at the nanoscale.

The use of X-ray diffraction makes the technique more accessible to scientists and allows for imaging a larger portion of the sample, said Andrej Singer, assistant professor of materials science and engineering and David Croll Sesquicentennial Faculty Fellow in Cornell Engineering, who led the research with doctoral student Ziming Shao.

“Imaging a large area is important because it represents the true state of the material,” Singer said. “The nanotexture measured by a local probe could depend on the choice of the probed spot.”

Read more on the CHESS website

Picking up good vibrations – of proteins – at CHESS

Picking up good vibrations – of proteins – at CHESS

A new method for analyzing protein crystals – developed by Cornell researchers and given a funky two-part name – could open up applications for new drug discovery and other areas of biotechnology and biochemistry.

The development, outlined in a paper published March 3 in Nature Communications, provides researchers with the tools to interpret the once-discarded data from X-ray crystallography experiments – an essential method used to study the structures of proteins. This work, which builds on a study released in 2020, could lead to a better understanding of a protein’s movement, structure and overall function.

Protein crystallography produces bright spots, known as Bragg peaks, from the crystals, providing high-resolution information about the shape and structure of a protein. This process also captures blurry images – patterns and clouds related to the movement and vibrations of the proteins – hidden in the background of the Bragg peaks.

These background images are typically discarded, with priority given to the bright Bragg peak imagery that is more easily analyzed.

“We know that this pattern is related to the motion of the atoms of the protein, but we haven’t been able to use that information,” said lead author Steve Meisburger, Ph.D. ’14, a former postdoctoral researcher in the lab of Nozomi Ando, M.S. ’04, Ph.D. ’09, associate professor of chemistry and chemical biology in the College of Arts and Sciences. “The information is there, but we didn’t know how to use it.  Now we do.”

Meisburger worked closely with Ando to develop the robust workflow to decode the weak background signals from crystallography experiments called diffuse scattering. This allows researchers to analyze the total scattering from crystals, which depends on both the protein’s structure and the subtle blur of its movements.

Their two-part method – which the team dubbed GOODVIBES and DISCOBALL – simultaneously provides a high-resolution structure of the protein and information on its correlated atomic movements.

GOODVIBES analyzes the X-ray data by separating the movements – subtle vibrations – of the protein from other proteins that might be moving around it. DISCOBALL independently validates these movements for certain proteins directly from the data, allowing researchers to trust the results from GOODVIBES and understand what the protein might be doing.

Read more on CHESS website

Image: Meisburger, Case, & Ando (2020) Nat Commun 11, 1271

How a record-breaking copper catalyst converts CO2 into liquid fuels

How a record-breaking copper catalyst converts CO2 into liquid fuels

Researchers at Berkeley Lab, collaborating with CHESS scientists at the PIPOXS beamline, have made the first real-time movies of copper nanoparticles as they evolve to convert carbon dioxide and water into renewable fuels and chemicals. Their new insights could help advance the next generation of solar fuels.

Since the 1970s, scientists have known that copper has a special ability to recycle carbon dioxide into valuable chemicals and fuels. But for many years, scientists have struggled to understand how this common metal works as an electrocatalyst, a mechanism that uses energy from electrons to chemically transform molecules into different products.

Now, a research team led by Lawrence Berkeley National Laboratory (Berkeley Lab) has gained new insight by capturing the world’s first real-time movies of copper nanoparticles (copper particles engineered at the scale of a billionth of a meter) as they convert CO2 and water into renewable fuels and chemicals: ethylene, ethanol, and propanol, among others. The work was reported in the journal Nature.

“This is very exciting. After decades of work, we’re finally able to show – with undeniable proof – how copper electrocatalysts excel in CO2 reduction,” said Peidong Yang, a senior faculty scientist in Berkeley Lab’s Materials Sciences and Chemical Sciences Divisions who led the study. Yang is also a professor of chemistry and materials science and engineering at UC Berkeley. “Knowing why copper is such an excellent electrocatalyst brings us steps closer to turning CO2 into new, renewable solar fuels through artificial photosynthesis.”

Read more on the CHESS website

Image: Artist’s rendering of a copper nanoparticle as it evolves during CO2 electrolysis: Copper nanoparticles (left) combine into larger metallic copper “nanograins” (right) within seconds of the electrochemical reaction, reducing CO2 into new multicarbon products.

Credit: Yao Yang/Berkeley Lab

Influence of alloying on slip intermittency and implications for dwell fatigue in titanium

Influence of alloying on slip intermittency and implications for dwell fatigue in titanium

The high precision of HEDM measurements at FAST offer new insight into the microscopic processes that cause dwell fatigue, pointing toward new alloying strategies for mitigation.

What is the discovery?

Titanium alloys exhibit a phenomenon known as dwell fatigue: when the alloys are held under persistent loads as low as 60% of yield stress, their fatigue lifetime is gradually reduced. The culprit for this degradation in performance is believed to be dislocation slip, which is an intermittent, scale bridging phenomenon, not unlike a nanoscale earthquake occurring in the alloy. Sudden dislocation slips can induce large stress bursts and initiate crack formation. In a new publication appearing in Nature Communications, a team lead by Felicity Worsnop (MIT) and David Dye (Imperial College London) has used high-energy diffraction microscopy at the FAST beamline at CHEXS to observe and quantify thousands of sudden “stress drop” events in thousands of different crystalline grains inside titanium alloys held under dwell fatigue conditions. The team was able to collect unprecedentedly precise statistics for the probability for different types of stress drop events to occur in different alloys. The figure below shows the probability for stress drops with magnitude equal to or greater than Δτ̅ and associated with the possible 3 slip modes (illustrated at right), in 4 different alloys (a – disordered Ti-7AL, low oxygen content; b – higher oxygen content; c – low oxygen, after aging; d – high oxygen, after aging). They discover that interstitial oxygen promotes slip homogeneity, with a higher frequency of smaller stress drops being observed, whereas precipitation of regions with aluminum ordering results in fewer, larger events. Basal slip is observed to be the most common of the slip modes and gives rise to the largest slip events.

Read more on the CHESS website

Protein family shows how life adapted to oxygen

Protein family shows how life adapted to oxygen

Cornell scientists have created an evolutionary model that connects organisms living in today’s oxygen-rich atmosphere to a time, billions of years ago, when Earth’s atmosphere had little oxygen – by analyzing ribonucleotide reductases (RNRs), a family of proteins used by all free-living organisms and many viruses to repair and replicate DNA.

“By understanding the evolution of these proteins, we can understand how nature adapts to environmental changes at the molecular level. In turn, we also learn about our planet’s past,” said Nozomi Ando, associate professor of chemistry and chemical biology in the College of Arts and Sciences and corresponding author of the study. “Comprehensive phylogenetic analysis of the ribonucleotide reductase family reveals an ancestral clade” published in eLife Digest Oct. 4.

Co-first authors of the study are Audrey Burnim and Da Xu, doctoral students in chemistry and chemical biology, and Matthew Spence, Research School of Chemistry, Australian National University, Canberra. Colin J. Jackson, professor of chemistry, Australian National University, Canberra, is a corresponding author.

This undertaking involved a large dataset of 6,779 RNR sequences; the phylogeny took several high-performance computers a combined seven months (1.4 million CPU hours) to calculate. Made possible by computing advances, the approach opens up a new way to study other diverse protein families that have evolutionary or medical significance.

RNRs have adapted to changes in the environment over billions of years to conserve their catalytic mechanism because of their essential role for all DNA-based life, Ando said. Her lab studies protein allostery – how proteins are able to change activity in response to the environment. The evolutionary information in a phylogeny gives us a way to study the relationship between the primary sequence of a protein and its three-dimensional structure, dynamics and function.

Read more on the CHESS website

Image: Tree inference on a ribonucleotide reductase (RNR) sequence dataset as included in the original report, “Comprehensive phylogenetic analysis of the ribonucleotide reductase family reveals an ancestral clade“.

Welcome Jeney Wierman – New MacCHESS Director

Welcome Jeney Wierman – New MacCHESS Director

Jeney Wierman started as the new MacCHESS Director on July 1st, 2022.  Below is a welcome message to the whole CHESS Community. 

Jeney takes over the MacCHESS directorship from Marian Szebenyi, who will be retiring later this year after 30 years at MacCHESS.

Dear CHESS Community,

It is (hopefully) no secret that I hold a very special place in my heart for CHESS, the people working here, and the community it supports. With that, I am honored and delighted to join CHESS this summer as Director of MacCHESS! First, I must thank Marian Szebenyi for continuing to work with me into the fall startup – I have large shoes to fill and appreciate the overlap support. Second, I would also like to thank all who were a part of the hiring process over the past few months, plus onboarding over the last week. Much appreciated.

It is thrilling to return to the CHESS family! The ingenuity and tenacity of the CHESS spirit (the can-do attitude) speak volumes of its brilliant people.

Read more on the CHESS website

Image: Jeney Wierman has started as the MacCHESS Director on July 1.