Lab Resolves Origin of Perovskite Instability

Lab Resolves Origin of Perovskite Instability

The following news release was originally issued by Princeton University. The story describes how researchers investigated the inorganic perovskite, cesium lead iodide, that has attracted wide attention for its potential in creating highly efficient solar cells. The researchers used x-ray diffraction performed at Princeton University and x-ray pair distribution function measurements performed at the National Synchrotron Light Source II (NSLS-II), a U.S. Department of Energy (DOE) Office of Science User Facility located at DOE’s Brookhaven National Laboratory, to find the source of thermodynamic instability in the perovskite. For more information about Brookhaven’s role in this research, please reach out to Cara Laasch, laasch@bnl.gov.  

Researchers in the Cava Group at the Princeton University Department of Chemistry have demystified the reasons for instability in an inorganic perovskite that has attracted wide attention for its potential in creating highly efficient solar cells.

Using single crystal X-ray diffraction performed at Princeton University and X-ray pair distribution function measurements performed at the Brookhaven National Laboratory, Princeton Department of Chemistry researchers detected that the source of thermodynamic instability in the halide perovskite cesium lead iodide (CsPbI3) is the inorganic cesium atom and its “rattling” behavior within the crystal structure.

Read more on NSLS II website

Image: Milinda Abeykoon, one of the lead beamline scientists at Brookhaven Lab, in preparation of the challenging experiments with Robert Cava’s team.

WE18 FERMI Slider

WE18 FERMI Slider

The program of construction and commissioning through user experiments of the FEL source FERMI, the only FEL user facility in the world currently exploiting external seeding to offer intensity, wavelength and line width stability, achieved all of its intended targets in 2017.

Looping X-rays to produce higher quality laser pulses

Looping X-rays to produce higher quality laser pulses

A proposed device could expand the reach of X-ray lasers, opening new experimental avenues in biology, chemistry, materials science and physics.BY ALI SUNDERMIER

Ever since 1960, when Theodore Maiman built the world’s first infrared laser, physicists dreamed of producing X-ray laser pulses that are capable of probing the ultrashort and ultrafast scales of atoms and molecules.

This dream was finally realized in 2009, when the world’s first hard X-ray free-electron laser (XFEL), the Linac Coherent Light Source (LCLS) at the Department of Energy’s SLAC National Accelerator Laboratory, produced its first light. One limitation of LCLS and other XFELs in their normal mode of operation is that each pulse has a slightly different wavelength distribution, and there can be variability in the pulse length and intensity. Various methods exist to address this limitation, including ‘seeding’ the laser at a particular wavelength, but these still fall short of the wavelength purity of conventional lasers.

Read more on the SLAC National Accelerator Laboratory website

Image: Schematic arrangement of the experiment. The researchers send an X-ray pulse from LCLS through a liquid jet, where it creates excited atoms that emit a pulse of radiation at one distinct color moving in the same direction. This pulse is reflected through a series of mirrors arranged in a crossed loop. The size of this loop is carefully set so that the pulse arrives back at the liquid jet at the same time as a second X-ray pulse from LCLS. This produces an even brighter laser pulse, which then takes the same loop. The process is repeated several times, and with each loop the laser pulse intensifies and becomes more coherent. During the last loop, one of the mirrors is quickly switched allowing this laser pulse to exit.

Credit: (Greg Stewart/SLAC National Accelerator Laboratory)

Apart Yet Together: Virtual 2020 NSLS-II & CFN Users’ Meeting

Apart Yet Together: Virtual 2020 NSLS-II & CFN Users’ Meeting

A record-breaking number of attendees gathered virtually at the NSLS-II & CFN Users’ Meeting to discuss the most recent developments in photon science and nanoscience

Upton—From May 18 to 20, more than 1500 registered attendees from 37 countries around the world participated in the first-ever virtual joint Users’ Meeting of the Center for Functional Nanomaterials (CFN) and the National Synchrotron Light Source II (NSLS-II)—two U.S. Department of Energy (DOE) Office of Science User Facilities at DOE’s Brookhaven National Laboratory. Holding the annual joint Users’ Meeting is a long-standing tradition at Brookhaven Lab, where attendees enjoy scientific discourse during the warm spring days on Long Island. 

While the Coronavirus pandemic limited the Lab’s ability to bring attendees on site for 2020, it presented a new opportunity for the conference organizers to hold a virtual Users’ Meeting, which attracted five times more attendees than ever before. The meeting included eight workshops, each held in a virtual meeting rooms with record-breaking numbers of attendees, ranging from 120 to more than 400. The meeting’s plenary session included more than 600 attendees listening and asking questions. 

Read more on the NSLS-II website

Image: NSLS-II aerial
Helping our immune systems bypass antibiotic resistance

Helping our immune systems bypass antibiotic resistance

Over 700,000 people die each year due to drug-resistant diseases and this figure could increase to 10 million per year by 2050, according to a 2019 report.

As the search continues for new antibiotics to treat drug-resistant infections, a group of researchers used the Canadian Light Source (CLS) at the University of Saskatchewan to address the problem from a different direction, by trying to weaken the ability of bacteria to develop resistance in the first place.

“The goal is to knock the bacterial cells down in terms of their resistance,” said Dr. Anthony Clarke, Professor and Dean of Science at Wilfrid Laurier University and adjunct professor at the University of Guelph. “We haven’t been successful over the last 30 years in finding new classes of antibiotics so, in the short term, we’re trying to weaken the cells so our own immune system can take over to fight infection.”

The target for his team’s work is peptidoglycan, which gives bacterial cell walls their rigidity. “Think of it as building a brick wall around the bacteria’s cells,” said Clarke. Since peptidoglycan can be broken down by lysozyme, an enzyme that exists in human immune systems, bacteria have developed strategies that block these enzymes by modifying their peptidoglycan, thereby “cementing the bricks in place,” and resisting our defences.

Read more on the Canadian Light Source website

Image: Dr. Clarke inspecting flasks of bacterial cultures in a student laboratory.

Cross-β Structure – a Core Building Block for Streptococcus mutans Functional Amyloids

Cross-β Structure – a Core Building Block for Streptococcus mutans Functional Amyloids

Most amyloids1 are misfolded proteins, having enormous variety in native structures. Pathological amyloids are implicated in diseases including Alzheimer’s disease and many others.  They are characterized by long, unbranched fibrillar structure, enhanced birefringence on binding Congo red dye, and cross-β structure – β-strands running approximately perpendicular to the fibril axis, forming long β-sheets running in the direction of the axis.  Fiber diffraction patterns from amyloids are marked by strong intensity at about 4.8 Å in the meridional direction (parallel to the fibril axis), corresponding to the separation of strands in a β-sheet, and in many cases broader but distinct equatorial intensity at about 10 Å.  The 10 Å intensity (whose position may vary considerably) comes from the distance between stacked β-sheets.  This stacking is characteristic of the many amyloids formed by small peptides, including peptide fragments of larger amyloidogenic proteins.  While some authors have required the 10 Å intensity to characterize an amyloid, it is not strictly necessary, since architecturally more complex examples have been found of Congo-red-staining fibrils with cross-β structure, but without the stacked-sheet structure, and consequently without the 10 Å intensity on the equator.

Amyloids do not always stem from protein misfolding.  Organisms across all kingdoms utilize functional amyloids in numerous biological processes.  Bacteria are no exception. Bacterial amyloids contribute to biofilm formation and stability.  Tooth decay is the most common infectious disease in the world.  A major etiologic agent, Streptococcus mutans, is a quintessential biofilm dweller that produces at least three different amyloid-forming proteins, adhesins P1 and WapP, and the cell density and competence regulator Smu_63c2.  The naturally occurring truncation derivatives of P1 and WapA, C123 and AgA, represent the amyloidogenic moieties, and a new paradigm of Gram-positive bacterial adhesins is emerging of adhesins having dual functions in monomeric and amyloid forms. While each S. mutans protein possesses considerable β-sheet structure, the tertiary structures of each protein are quite different (Fig. 1).  This study further characterized S. mutans amyloids and addressed the ongoing debate regarding the underlying structure and assembly of bacterial amyloids including speculation that they are structurally dissimilar from better-characterized amyloids.

Read more on the SSRL website

Image: Crystal or predicted 3D structures of S. mutans C123 (left), AgA (center), and Smu_63c (right).

A polymer coating makes Metal Organic Frameworks better at delivering drugs

A polymer coating makes Metal Organic Frameworks better at delivering drugs

Researchers use Synchrotron InfraRed microspectroscopy to study the dynamics of drug release from MOFs

How to efficiently deliver targeted, controlled and time-released doses of drugs is a significant challenge for biomedicine. Finding solutions to this challenge would result in substantial benefits for patients, including more effective drug therapy and fewer undesirable side effects. The porous nature of metal-organic frameworks (MOFs) makes them attractive candidates for drug-delivery systems as they can be tailored to hold and transport a variety of encapsulated guest molecules. To this end, employing MOFs as a drug delivery vehicle could offer potential solutions to accomplish the targeted and controlled release of anti-cancer drugs. However, understanding the precise chemical and physical transformations that MOFs undergo as these guest molecules are released is challenging. In work recently published in ACS Applied Materials & Interfaces, researchers from the University of Oxford, University of Turin, and Diamond Light Source used a combination of experimental and theoretical techniques to address this problem. They show how the combination of hydrophilic MOF-encapsulated drug with a hydrophobic polymeric matrix is a highly promising strategy to tune the drug release rate for optimal delivery. Their results demonstrate that high-resolution synchrotron InfraRed microspectroscopy is a powerful in situ technique for tracking the local chemical and physical transformations, revealing the dynamics underpinning the controlled release of drug molecules bound to the MOF pores.  

Read more on Diamond Light Source website

Image: Using synchrotron infrared radiation to track the drug release process from MOF/Polymer composites.

Every moment of ultrafast chemical bonding now captured on film

Every moment of ultrafast chemical bonding now captured on film

The emerging moment of bond formation, two separate bonding steps, and subsequent vibrational motions were visualized.

Targeted cancer drugs work by striking a tight bond between cancer cell and specific molecular targets that are involved in the growth and spread of cancer. Detailed images of such chemical bonding sites or pathways can provide key information necessary for maximizing the efficacy of oncogene treatments. However, atomic movements in a molecule
have never been captured in the middle of the action, not even for an extremely simple molecule such as a triatomic molecule, made of only three atoms. A research team led by IHEE Hyotcherl of the Institute for Basic Science (IBS, South Korea) (Professor, Department of Chemistry, KAIST), in collaboration with scientists at the Institute of Materials Structure Science of KEK (KEK IMSS, Japan), RIKEN (Japan) and Pohang Accelerator Laboratory (PAL, South Korea), reported the direct observation of the birthing moment of chemical bonds by tracking real-time atomic positions in the molecule. “We finally succeeded in capturing the ongoing reaction process of the chemical bond formation in the gold trimer. The femtosecond-resolution images revealed that such molecular events
took place in two separate stages, not simultaneously as previously assumed,” says Associate Director IHEE Hyotcherl, the corresponding author of the study. “The atoms in the gold trimer complex atoms remain in motion even after the chemical bonding is complete. The
distance between the atoms increased and decreased periodically, exhibiting the molecular vibration. These visualized molecular vibrations allowed us to name the characteristic motion of each observed vibrational mode.” adds Ihee.

>Read more on the KEK (Photon Factory) website

Image: Figure 2. (left) Time-dependent positions of the wave packet in the multidimensional nuclear coordinates were obtained from the femtosecond x-ray scattering experiment on a gold trimer complex. (Credit: Nature & IBS) (right) By inspecting the motion of the wave packet, it was revealed that the bond formation reaction in the gold trimer complex occurs through an asynchronous bond formation mechanism. (Yellow: gold atoms, gray: carbon atom, blue: nitrogen atom, 1000 times 1 fs is 1 picosecond (ps), 1000 times 1 ps is 1 nanosecond (ns))

Credit: KEK IMSS

Unravelling the secrets of the malaria parasite

Unravelling the secrets of the malaria parasite

PETRA III helps to identify a new kind of protein in Plasmodium falciparum

For the first time, scientists have identified a lipocalin protein in the malaria parasite Plasmodium falciparum. The discovery helps to better understand the life cycle of the parasite that is a major health burden in large parts of the world. The cooperation between the groups of Tim Gilberger from the Centre for Structural Systems Biology CSSB (Cellular Parasitology Department at Bernhard Nocht Institute for Tropical Medicine/ Universität Hamburg) at DESY and Matthias Wilmanns from the Hamburg branch of the European Molecular Biology Laboratory EMBL describes the discovery in the journal Cell Reports. CSSB is a cooperation of nine institutions, including DESY, that have deputed scientists to the centre.

With an estimated 228 million cases per year worldwide and more than 400,000 deaths, malaria remains one of the most important human health threats. There is no vaccine commercially available. While biologists have revealed many details about how the malaria parasite rapidly feeds on and transforms its host’s red blood cells, there are many unsolved mysteries surrounding the parasite’s life cycle. Using the microscopic facilities available at CSSB in combination with EMBL’s X-ray beamlines at DESY’s research light source PETRA III, the team unraveled a small piece of this mystery with the identification and characterization of the first lipocalin in the most virulent malaria parasite species P. falciparum.

Read more on the PETRA III (at DESY) website

Image: Ribbon diagram of the protein structure of Plasmodium falciparum Lipocalin PfLCN that comes in tertramers, i.e. complexes of four identical molecules. Fluorescence micrographs of the parasite (upper right and lower left) show that the lipocalin accumulates in vacuoles.

Credit: BNITM/EMBL, Paul-Christian Burda/Thomas Crosskey [Source]

A highly promising sustainable battery for electric vehicles

A highly promising sustainable battery for electric vehicles

McGill University researchers show that affordable materials could prove key for improving the batteries used in electric vehicles. The breakthrough was analyzed and confirmed with the Canadian Light Source (CLS) at the University of Saskatchewan. The research was funded by NSERC and supported by Hydro-Quebec.

As we move to greener technologies, the need for affordable, safe and powerful batteries is increasing constantly.

Battery-powered electric vehicles, for example, have much higher safety standards than our phones, and to travel the long distances required in Canada, lighter weight, high-energy capacity batteries make a world of difference.

Current rechargeable batteries tend to use expensive non-abundant metals, like cobalt, that carry an environmental and human rights toll under the poor labour conditions in mines in Africa. All are barriers to wider adoption.

The battery’s cathode, or positive electrode, is one of the best candidates for Li-ion battery improvement. “Cathodes represent 40 per cent of the cost of the batteries that we are using in our phones right now. They are absolutely crucial to improve battery performance and reduce dependency on cobalt,” says Rasool.

Read more on the Canadian Light Source website

Image : Lithium ion silicate nanocrystals coated in a conducting polymer known as PEDOT enhance battery performance even after 50 cycles, paving the way for high energy density cathodes.

Unexpected rise in ferroelectricity as material thins

Unexpected rise in ferroelectricity as material thins

SCIENTIFIC ACHIEVEMENT

Researchers working at the Advanced Light Source (ALS) showed that hafnium oxide surprisingly exhibits enhanced ferroelectricity (reversible electric polarization) as it gets thinner.

SIGNIFICANCE AND IMPACT

The work shifts the focus of ferroelectric studies from more complex, problematic compounds to a simpler class of materials and opens the door to novel ultrasmall, energy-efficient electronics.

Ferroelectric lower limit?

Distortions in the atomic geometries of certain materials can lead to ferroelectricity—the presence of electric dipoles (charge separations) with switchable polarizations. The ability to control this polarization with an external voltage offers great promise for ultralow-power microprocessors and nonvolatile memory.

As electronic devices become smaller, however, the materials used to store and manipulate electronic data are being pushed to low-dimensional extremes. Properties that function reliably in bulk materials often diminish in ultrathin films just a few atomic units thick. Therefore, exploring the critical thickness limit in “polar” materials (i.e., materials having spontaneous electric polarization) is not only a fundamental issue for nanoscale ferroelectric research, it also has extensive implications for the future of high-density ferroelectric-based electronics.

Read more on Advanced Light Source (ALS) website

Image : A thin layer of hafnium oxide (two unit-cell thicknesses, or about 1 nm) has an electric polarization that’s reversible by an external electric field, making it attractive for use in next-generation low-power microelectronics.

Credit: Ella Maru Studio

First megahertz rate timing jitter observed

First megahertz rate timing jitter observed

A report published today in the Journal Optica demonstrates accurate synchronisation of optical and X-ray lasers crucial for pump-probe experiments at XFEL. These snapshots taken during a reaction are stitched together to make molecular movies.

One of the ultimate goals for scientists using state-of-the-art X-ray free-electron lasers such as European XFEL is to be able to film the details of chemical and biological reactions. By stitching together a series of snapshots taken at different time intervals during a reaction, a molecular movie can be made of the process. So called pump-probe experiments use a precisely synchronised optical laser to trigger a reaction (the ‘pump’), while the X-ray laser takes a snapshot of the molecular structure at defined times during the reaction (the ‘probe’).

European XFEL now generates the ultrafast and ultra-intense light pulses needed to capture these processes that occur on extremely short timescales. The pulses of X-ray light generated by European XFEL are each less than a few millionths of a billionth of a second, or a few femtoseconds – fast enough to capture the series of events in a biological or chemical reaction. An accurate synchronization of the X-ray and optical laser pulses at these timescales is, however, challenging. Furthermore, tiny variations in the alignment and path travelled by the laser pulses caused, for example, by fluctuations in air pressure, or expansion in the electrical cables, have a relatively large impact on the accuracy of this experimental set-up. This variation is known as ‘timing jitter’. For pump-probe experiments to be successful, the jitter must be kept to a minimum, and be accurately characterized so that scientists can take it into account when assessing their data.

Read more on the European XFEL website

Image : The XPB/SFX instrument at European XFEL.

Credit: European XFEL / Jan Hosan
Clay haloes preserve ancient fossils: an Infrared view

Clay haloes preserve ancient fossils: an Infrared view

A UK-US collaboration has shed light on the preservation of ancient microfossils. As outlined in Interface Focus, the presence of kaolinite haloes surrounding the tiny fossils is believed to have kept destructive bacteria at bay, stopping decay. The small molecular differences of the clay around the fossils called for the Synchrotron IR microbeam.

Fossils that are over 500 million years old are extremely rare because early organisms were microscopic, only the thickness of a hair, and lacked hard parts that can resist decay. To understand how these early organisms could be preserved, IR microspectroscopy was performed using the Multimode InfraRed Imaging and Microspectroscopy (MIRIAM) beamline at Diamond Light Source. IR microanalysis allowed researchers to identify at the micron scale the minerals surrounding 800–1,000 million-year-old microfossils, and it was determined that an aluminium-rich clay known as kaolinite was responsible for their preservation. Kaolinite was previously shown to be toxic to bacteria, so its presence prevented the early organisms from being destroyed.

These observations suggest that the early fossil record might be biased to regions that are rich in kaolinite, such as the tropics. Moreover, the lack of animal fossils in these samples, despite having favourable fossilisation conditions demonstrates that animals were yet to evolve 800 million years ago.

Read more on the Diamond Light Source website

Image: Light microscopy images (left) indicating the position of the microfossils (red boxes) and Synchrotron-based IR maps (right) showing the compositional variation of the clay around the fossil (as ratio of 3694 cm^-1 band vs the M-OH region). 

Credit: Data taken at MIRIAM beamline B22 at Diamond.