Understanding how alkaline treatment affects bamboo

In China, bamboo is a symbol of longevity and vitality, able to survive the hardest natural conditions and remain green all year round. In a storm, bamboo stems bend but do not break, representing the qualities of durability, strength, flexibility and resilience1.

Bamboo is a traditional construction material in Asia. Its strength and flexibility arise from its hollow stems (‘culms’) made from distinct material components. The solid outer shell of the culm is made primarily from longitudinal fibres. A higher density at the outer wall makes it stronger than the inner regions, and results in remarkable stiffness and flexural strength. Running through the centre of bamboo stem are parenchyma cells that store and channel the plant’s nutrients.

At the micro-/nano-scale both the fibres and the matrix contain cellulose nano-fibrils of the same type. However, the structural arrangement of the two materials result in contrasting mechanical properties. Individual fibres may reach a strength of 900 MPa, whilst the matrix can only resist about 50 MPa. There is also a considerable difference in their elastic properties, with the fibres being much stiffer than the matrix.

Bamboo is often treated with alkaline solutions, to modify these properties. Alkaline treatments can turn this rapidly renewable and low-cost resource into soft textiles, and extract fibres to be used in composite materials or as biomass for fuel.

>Read more on the Diamond Light Source website

Image: Dr Enrico Salvati on the B16 beamline at Diamond.

X-ray laser opens new view on Alzheimer proteins

Graphene enables structural analysis of naturally occurring amyloids

A new experimental method permits the X-ray analysis of amyloids, a class of large, filamentous biomolecules which are an important hallmark of diseases such as Alzheimer’s and Parkinson’s. An international team of researchers headed by DESY scientists has used a powerful X-ray laser to gain insights into the structure of different amyloid samples. The X-ray scattering from amyloid fibrils give patterns somewhat similar to those obtained by Rosalind Franklin from DNA in 1952, which led to the discovery of the well-known structure, the double helix. The X-ray laser, trillions of times more intense than Franklin’s X-ray tube, opens up the ability to examine individual amyloid fibrils, the constituents of amyloid filaments. With such powerful X-ray beams any extraneous material can overwhelm the signal from the invisibly small fibril sample. Ultrathin carbon film – graphene – solved this problem to allow extremely sensitive patterns to be recorded. This marks an important step towards studying individual molecules using X-ray lasers, a goal that structural biologists have long been pursuing. The scientists present their new technique in the journal Nature Communications.

Amyloids are long, ordered strands of proteins which consist of thousands of identical subunits. While amyloids are believed to play a major role in the development of neurodegenerative diseases, recently more and more functional amyloid forms have been identified. “The ‘feel-good hormone’ endorphin, for example, can form amyloid fibrils in the pituitary gland. They dissolve into individual molecules when the acidity of their surroundings changes, after which these molecules can fulfil their purpose in the body,” explains DESY’s Carolin Seuring, a scientist at the Center for Free-Electron Laser Science (CFEL) and the principal author of the paper. “Other amyloid proteins, such as those found in post-mortem brains of patients suffering from Alzheimer’s, accumulate as amyloid fibrils in the brain, and cannot be broken down and therefore impair brain function in the long term.”

Image: On the ultra-thin, extremely regular layer of graphene, the fibrils align themselves in parallel in large domains. The intense X-ray light from the X-rax free-electron laser LCLS at the SLAC National Accelerator Center enabled the researchers to gain partial information about the fibril structure from ensembles of just a few fibrils.
Credit: Greg Stewart/SLAC National Accelerator Laboratory

A new Polarisation Analyser, and the benefits of 3D printing

The I16 beamline at Diamond is dedicated to the study of advanced materials using X-ray diffraction; part of this process is to use a device, known as a polarisation analyser (PA) that can analyse magnetic scattering from samples. Magnetic scattering is different to, and weaker than, normal X-ray scattering and analysis of the polarisation of this scattering can be used to gain insights into the magnetic properties of materials. Researchers can use this information to determine details of the 3D structure of the sample material.

The design of the PA includes an assembly of vacuum chambers, sets of slits to remove unwanted scattering and various detectors, arranged to rotate about different axes. Researchers use data collected from the detectors as they are moved and rotated to build up information on the polarisation of the scattering.

>Read more on the Diamond Light Source website

Image: extract of the polarisation analyser; to watch the video “The motion of the main axes of the polarisation analyser”, please have a look here.

 

Scientists use machine learning to speed discovery of metallic glass

In a new report, they combine artificial intelligence and accelerated experiments to discover potential alternatives to steel in a fraction of the time.

Blend two or three metals together and you get an alloy that usually looks and acts like a metal, with its atoms arranged in rigid geometric patterns.

But once in a while, under just the right conditions, you get something entirely new: a futuristic alloy called metallic glass that’s amorphous, with its atoms arranged every which way, much like the atoms of the glass in a window. Its glassy nature makes it stronger and lighter than today’s best steel, plus it stands up better to corrosion and wear.

Even though metallic glass shows a lot of promise as a protective coating and alternative to steel, only a few thousand of the millions of possible combinations of ingredients have been evaluated over the past 50 years, and only a handful developed to the point that they may become useful.

Now a group led by scientists at the Department of Energy’s SLAC National Accelerator Laboratory, the National Institute of Standards and Technology (NIST) and Northwestern University has reported a shortcut for discovering and improving metallic glass – and, by extension, other elusive materials – at a fraction of the time and cost.

>Read more on the SLAC website

Image: Fang Ren, who developed algorithms to analyze data on the fly while a postdoctoral scholar at SLAC, at a Stanford Synchrotron Radiation Lightsource beamline where the system has been put to use.
Credit: Dawn Harmer/SLAC National Accelerator Laboratory

Inscuteable: No longer inscrutable

The structure and function of a controller of stem cell division

An important complex forming the core of the cell division apparatus in stem cells has been imaged using the Macromolecular Crystallography beamlines, I04 and I04-1 at Diamond Light Source. As recently reported in Nature Communications, the spindle orientation protein known as LGN bound to an adapter protein known as Inscuteable in a tetrameric arrangement, which drove asymmetric stem cell division.

Stem cells are undifferentiated cells that have the capacity to differentiate into specialised cells. In a developing embryo, stem cells are the foundation of all other cells, whereas in adults, they can aid repair by replenishing lost tissue. To ensure a physiological balance between differentiated and undifferentiated cells, stem cells undergo asymmetric division to give rise to an identical daughter stem cell and a differentiated cell.

Asymmetric division occurs when there is an unequal segregation of cellular contents. For this to occur, the line of division of the cell (known as the axis) must be carefully positioned. The stem cells use polarity proteins, such as Par3, to determine the location of this axis, and then proteins such as LGN and Inscuteable (Insc) help to align the mitotic spindle to the axis of polarity.

Despite the importance of such a process, little is known about the interactions between the proteins. Dr Marina Mapelli, Group Leader at the European Institute of Oncology in Milan and Dr Simone Culurgioni, Post-Doctoral Research Associate here at Diamond, along with scientists from the Italian Institute of Technology, plus the European Molecular Biology Laboratory in Grenoble set out to solve the crystal structure of LGN bound to Insc. They saw that the proteins were intertwined in a fascinating tetrameric arrangement and found that Insc alone had impressive anti-proliferative properties.

>Read more on the Diamond Light Source website

Figure : On the left, a stem cell orienting (movement highlighted by the red arrow) its mitotic spindle (in green) in order to partition its cellular components (in pink and yellow) unequally in the two daughter cells; one is retaining the stem state (in pink) and the other one is committed to differentiate (in yellow). On the right, the structure of Insc:LGN complex governing this asymmetric cell division process. Insc:LGN complex assembles in highly stable intertwinned tetrameric structure (Insc in blue and purple, LGN in yellow and orange respectively
Entire image here.

COSMIC impact: next-gen X-ray microscopy platform now operational

A next-generation X-ray beamline now operating at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) brings together a unique set of capabilities to measure the properties of materials at the nanoscale.

Called COSMIC, for Coherent Scattering and Microscopy, this X-ray beamline at Berkeley Lab’s Berkeley Lab’s Advanced Light Source (ALS) allows scientists to probe working batteries and other active chemical reactions, and to reveal new details about magnetism and correlated electronic materials.
COSMIC has two branches that focus on different types of X-ray experiments: one for X-ray imaging experiments and one for scattering experiments. In both cases, X-rays interact with a sample and are measured in a way that provides, structural, chemical, electronic, or magnetic information about samples.

The beamline is also intended as an important technological bridge toward the planned ALS upgrade, dubbed ALS-U, that would maximize its capabilities.

>Read more on the Advanced Light Source website

Image: X-rays strike a scintillator material at the COSMIC beamline, causing it to glow.
Credit: Simon Morton/Berkeley Lab

Major upgrade of the NCD beamline

The NCD beamline, now NCD-SWEET, devoted to Small Angle and Wide Angle X-ray Scattering (SAXS, WAXS), is offering users further experimental possibilities and higher quality data.

The SAXS beamline of ALBA has gone through a major upgrade in 2017. Upgraded items in the SAXS WAXS experimental techniques (SWEET) involve a new monochromator system, a new photon counting detector (Pilatus 1M), a new sample table with an additional rotating stage, and a beam conditioning optics with µ-focus and GISAXS options.

The original double crystal monochromator (DCM) has been replaced by a channel-cut silicon (1 1 1), improving the beam stability at sample position up to 0.9% and 0.4% of the beam size horizontally and vertically, respectivelly.

>Read more on the ALBA website

Figure: Vertical beam profile with the Be lenses into the beam (Horizontal axis unit is mm). The plot is the derivative of an edge scan along the vertical direction. The horizontal beam profile shows a gaussian shape as well.

Precise layer growth in a superlattice controls electron coupling and magnetism

Two-dimensional (2-D) crystalline films often exhibit interesting physical characteristics, such as unusual magnetic or electric properties. By layering together distinct crystalline thin films, a so-called “superlattice” is formed. Due to their close proximity, the distinct layers of a superlattice may significantly affect the properties of other layers. In this research, single 2-D layers of strontium iridium oxide were sandwiched between either one, two, or three layers of strontium titanium oxide to form three distinct superlattices. Researchers then used x-ray scattering at the U.S. Department of Energy’s Advanced Photon Source (APS) to probe the magnetic structure of each superlattice. The x-ray data revealed that the number of layers of the titanium-based material produced a dramatic difference in the magnetic behavior of the iridium-based layer. These findings are especially significant because the iridium compound is one of the perovskites, a class of materials known for their unique electric, magnetic, optical, and other properties that have proven useful in sensor and energy-related devices, and which are being intensively investigated for their application towards improved electronics and other technologies.

>Read more on the Advance Photon Source website
Image: Fig. 1. Illustration of superlattices. Panel (a) shows the Sr2IrO4 crystalline superlattice, with alternating layers of SrIrO3 and SrO. The SrIrO3 layers are perovskites, depicted as diamond-like shapes formed by six oxygen atoms; inside each diamond is a gold-colored iridium ion (cation), while pink strontium ions lay near the diamond’s ends. The SrIrO3 layers are separated by non-perovskite (inert) SrO layers, depicted as pink bars. Panel (b) shows the more-recently developed SrIrO3/SrTiO3 superlattice used for this research. Three distinct SrIrO3/SrTiO3 superlattices were created, having 1, 2, or 3 layers of inert SrTiO3 layers (colored green) separating the active SrIrO3 layers. Bold green boxes highlight the number of inert SrTiO3 layers in the three distinct lattices. While both SrIrO3 (gold diamonds) and SrTiO3 (green diamonds) are perovskites, the green-colored SrTiO3 layers buffer the active SrIrO3 layers. (The entire image is visible here)

Structural Mechanisms of Histone Recognition by Histone Chaperones

Chromatin is the complex of DNA and proteins that comprises the physiological form of the genome. Non-covalent interactions between DNA and histone proteins are necessary to compact large eukaryotic genomes into relatively small cell nuclei. The nucleosome is the fundamental repeating unit of chromatin, and is composed of 147bp of DNA wrapped around an octamer of histone proteins: 2 copies of each H2A, H2B, H3 and H4.

Assembly of nucleosomes in the cell requires the coordinated effort of many proteins including ATP-dependent chromatin remodeling enzymes and ATP-independent histone chaperone proteins. Histone chaperones are a large class of proteins responsible for binding the highly basic histone proteins, shielding them from non-specific interactions, facilitating nuclear import of histones, and finally depositing histones onto DNA to form nucleosomes. Despite performing many overlapping functions, histone chaperone proteins are highly structurally divergent. However, nearly all histone chaperones contain highly charged intrinsically disordered regions (IDRs)1. In many cases truncation of these conserved regions results in loss of histone affinity and deposition functions.

>Read more on the Stanford Synchrotron Radiation Lightsource

Image: (extract) SAXS analysis of Npm Core+A2 truncation (1-145) bound to five H2A/H2B dimers. Left: small angle x-ray scattering curve of the complex (purple dots). Simulated SAXS curve from the best scoring structural model shown as a black line. Right: SAXS envelope of the complex (pink) with the best scoring structural model inside. Positioning of H2A/H2B dimers by NMR and SAXS structural restraints. Full image here.

Tuning magnetic frustration in a dipolar trident lattice

Frustrated interactions are key to a wide range of phenomena, from protein folding and magnetic memory to fundamental studies of emergent exotic states.

Geometrical frustration and “spin ice”

When bar magnets are brought together, opposite poles will attract and like poles will repel, and the magnets will arrange themselves accordingly, to minimize energy. However, if the magnets are constrained to a lattice structure where each one has just two possible orientations, some magnets could end up geometrically “frustrated,” with neither orientation being lower in energy than the other. The system becomes what’s known as a “spin ice,” analogous to water ice, which retains intrinsic randomness (residual entropy) even at absolute zero.

Systems incorporating geometrical frustration are fascinating because their hard-to-predict behavior is key to a wide range of phenomena, from protein folding and magnetic memory to the emergence of exotic states of matter. For example, the emergence of magnetic monopole–like excitations in spin ice raises the intriguing possibility of “magnetic-charge” circuitry based on currents of magnetic monopole excitations.

>Read more on the Advanced Light Source website

Image: (extract, entire image here) Magnetic scattering patterns calculated from XMCD data for various lattice parameters. While relatively sharp peaks indicative of long-range order are seen in (a) and (c), the diffuse patterns in (b) indicate highly disordered configurations.

 

An energy-resolution record for resonant inelastic x-ray scattering

Resonant inelastic x-ray scattering (RIXS) is a powerful technique for studying electronic excitations in a wide variety of new and complex materials, offering momentum- and energy-resolution and potentially even analysis of scattered polarization. Since its inception in the 1990s, the development of RIXS instrumentation and scientific subjects have benefited from a closely intertwined evolution; improvements in energy resolution and throughput, spurred by specific scientific cases, have in turn made new subjects of study feasible. In the continued quest for substantially improved energy resolution, a novel prototype RIXS flat-crystal spectrometer was recently tested at X-ray Science Division beamline 27-ID-B at the U.S. Department of Energy’s Advanced Photon Source (APS). The spectrometer established a new record resolution for RIXS below 10 meV, together with a promise to do even better soon.

Early RIXS work was aimed at the study of charge transfer excitations in transition metal oxides (TMO), including the high-Tc superconducting Cuprates, where electronic excitations could be observed at a few eV. As the understanding of strongly correlated electron systems progressed, orbital degrees of freedom came into focus: in many Mott insulators, transitions between the active d-orbitals, the “dd excitations”, were hot topics and could reliably be observed with the then state-of-the-art resolution of 100-200 meV. Magnetism and magnetic ordering are central questions in the study of correlated electron systems. For example, the layered perovskite Iridates showing strikingly similar magnetic exchange interactions as the Cuprates, implying that unconventional superconductivity might be found here, to the intriguing assertion that magnetic properties of honeycomb Iridates might point to a quantum spin liquid as ground state of this material, the spectrum of novel, exotic properties uncovered or anticipated promise a treasure trove of scientific discoveries. In the late 2000s, RIXS was established as a probe of magnetic excitations. However, spectral features associated with magnetic excitations (“magnons”) lie at a fraction of an eV or even in the sub-10meV regime. A significant advance in energy resolution is needed to attack such subjects with RIXS.

>Read more on the Advanced Photon Source website

Figure: Schematic rendering of the new flat-crystal RIXS spectrometer.

Kilian Peter Heeg wins ESRF Young Scientist award

Kilian Peter Heeg has been awarded the title of Young Scientist 2018 by the ESRF User Organisation in recognition of his pioneering work on light-matter interactions enabling resonant brilliance enhancement of X-ray pulses. This award is presented every year at the ESRF annual User Meeting to a scientist aged 37 or younger for outstanding work conducted at the ESRF.

Kilian Heeg is a physicist and postdoctoral researcher at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. Aged just 31, Kilian has already significantly shaped the field of X-ray quantum optics.

Kilian says: “I wanted to be a mathematician when I was a child and I was always fascinated by natural sciences. However in my final years in school I fell in love with physics and very quickly became fascinated with quantum mechanics and especially quantum optics. I feel very honoured and pleased to have been chosen as the winner of this year’s ESRF Young Scientist Award.”

>Read more on the ESRF website

Image: Kilian on ESRF’s ID18 beamline
Credit: ESRF/C. Argoud

Questioning the universality of the charge density wave nature…

… in electron-doped cuprates

The first superconductor materials discovered offer no electrical resistance to a current only at extremely low temperatures (less than 30 K or −243.2°C). The discovery of materials that show superconductivity at much higher temperatures (up to 138 K or −135°C) are called high-temperature superconductors (HTSC). For the last 30 years, scientists have researched cuprate materials, which contain copper-oxide planes in their structures, for their high-temperature superconducting abilities. To understand the superconducting behavior in the cuprates, researchers have looked to correlations with the charge density wave (CDW), caused by the ordered quantum field of electrons in the material. It has been assumed that the CDW in a normal (non-superconducting) state is indicative of the electron behavior at the lower temperature superconducting state. A team of scientists from SLAC, Japan, and Michigan compared the traits of superconducting and non-superconducting cuprate materials in the normal state to test if the CDW is correlated to superconductivity.

>Read more on the SSRL website

Picture: explanation in detail to read in the full scientific highlight (SSRL website)

 

 

 

G. Ghiringhelli and L. Braicovich win 2018 Europhysics Prize of Condensed Matter

>Read more on the ESRF website

 

First users welcomed to I21

Diamond’s Inelastic X-ray Scattering beamline has celebrated an important milestone.

This new beamline is dedicated to Resonant Inelastic X-ray Scattering (RIXS) producing highly monochromatised, focused and tunable X-rays. It is suited to investigate the electronic, magnetic and lattice dynamics of samples particularly those with magnetic and electronic interactions.

“Considering the exceptional progress of the RIXS technique in the last few years, and the unique capabilities that I21 will offer to our UK and international community, we are extremely pleased to celebrate first users on I21,” says Laurent Chapon, Physical Sciences Director at Diamond. “Dr Kejin Zhou and his team, Diamond’s engineers and all support groups have worked incredibly hard to deliver this new beamline with an energy resolution and count rates already very close to the expected final targets. This is just the start of a great adventure, and we are looking forward to exploiting I21’s high-resolution for measurements of local and collective excitations in solid state materials. Our future investments to extend the energy range as well as delivering a polarimeter will reinforce the position of I21 as a world-leading facility.”

>Read More on the Diamond Light Source website

Photo: The I21 beamline time with first users from university of Bristol.