Catalytic role of oxygen-containing groups on carbon electrodes

The electrochemical reduction of oxygen plays a significant role in many critical applications such as gas sensors, hydrogen peroxide electrosynthesis, and electrochemical energy storage. Oxygen reduction reaction (ORR) drives the operation of fuel cells and metal-air batteries. The latter potentially can provide the highest specific energy among energy storage devices.

To increase the ORR efficiency, a catalyst immobilized on (or mixed with) conductive support is introduced to the positive electrode composition. Usually, porous sp2-carbon materials, like graphene, serve as such supporting materials. Its electronic configuration (sp2) provides the sufficient electric conductivity to the positive electrode. Nevertheless, ORR proceeds too slowly on the neat surface of ideal sp2-carbon in the absence of a catalyst.

The role of graphene imperfections (vacancies, impurity atoms, and functional groups) on catalyzing ORR (mainly in aqueous media) has been under intense investigation during the last decades. However, little is known about the effect of oxygen functionalization of carbon onORR in aprotic media (lacking the acidic protons). The interest in this process, especially in the presence of metal ions in the electrolyte, is relevant for various aprotic metal-oxygen batteries (lithium, sodium, magnesium, etc.) which are now considered as the most promising electrochemical power sources due to their outstanding theoretical performance. For such devices carbon electrodes are highly attractive due to their light weight and low cost, and the effect of carbon surface chemistry on the processes occurring upon battery operation is of great importance.

The present research shows for the first time that oxygenation of carbon electrode surface does not affect the rate of one-electron oxygen reduction in aprotic media. At the same time, in Li+-containing electrolytes, oxygen groups enhance both the rate of electrochemical Li2O2 formation and carbon electrode degradation due to faster oxidation by lithium superoxide (LiO2) intermediate yielding carbonate species as a product.

The research is led by scientists from Lomonosov Moscow State University and the Semenov Institute of Chemical Physics, in collaboration with FriedrichAlexanderUniversität Erlangen-NürnbergIFW DresdenSaint Petersburg State UniversityDonostia International Physics Center and Massachusetts Institute of Technology. 

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Image: C 1s core level spectra of a) pristine and b) oxidized graphene electrodes before and after discharge. C) Model spectroelectrochemical Li-O2 cell. D) Evolution of C 1s components’ ratios upon discharge for pristine and oxidized graphene.

Cadmium contamination in rice crops

Cadmium is a harmful element due to its toxicity and long half-life time in human bodies. It is an extremely toxic industrial and environmental pollutant classified as a human carcinogen. Cereals are indeed the major sources of cadmium for humans and, in particular, rice, a staple food in several Asian countries, is a particularly high source of this heavy metal.

To reduce cadmium concentrations in rice, the mechanisms that determine its availability from soil to plants, its plant uptake and its transport processes need to be well understood. The present study, resulting from a scientific collaboration involving young researchers among international institutions and large scale facilities between France, Switzerland, Italy, Spain and Japan (the University of Grenoble Alpes, the ETH Zurich institute, the Okayama University, the Ente italiano Nazionale Risi and the ALBA and Soleil synchrotrons), aims to enlighten these mechanisms.

Cadmium usually binds to sulfur, getting immobilized, and the bindings with sulfur is the major driving force for cadmium isotope fractionation (when the isotopic composition of an element of a given compound changes by the transition of that compound from one physical state or chemical composition to another).

The results of this research show how soil flooding in the rice crops not only changed the cadmium speciation in the solid soils but also in soil-aqueous solutions, while vacuolar transport includes the dissociation of heavy cadmium isotopes from a sulfur donor atoms prior to membrane transport and storage in the vacuole. All these findings allow a better tracing of contaminant elements in the complex soil-plant system and permit to asset about final product toxicity when those plants are source of human food.

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Image: rice crops

New material with reversible pressure-induced cooling effect properties

The study of materials with giant caloric effect (reversible thermal changes induced by an external stimulus), is currently a hot topic in Materials Science since they are the best-placed candidates to develop new efficient and environmentally friendly refrigerators that must replace current devices, which feature low efficiency and use hazardous fluids.

Extensive research has shown that the caloric effects in solid-state materials can be triggered by various external stimuli: magnetic field (magnetocaloric effect), electric field (electrocaloric effect), uniaxial stress (elastocaloric effect), hydrostatic pressure (barocaloric effect) or a combination of different stresses.

While magnetocaloric and electrocaloric effects require magnetically or electrically polarized materials, barocaloric effects can be found in any compressible material, which make them more interesting.

There is therefore a need to find out caloric materials exhibiting both large isothermal entropy and adiabatic temperature changes, for which these changes are reproducible upon cyclic application and removal of hydrostatic pressure.

A research, recently published in Advanced Materials, studies the barocaloric properties of Fe3(bntrz)6(tcnset)6, a molecular material that contains a metal complex that undergoes an abrupt spin-state switching (spin-crossover transition) close to room temperature. The work was carried out by a team from the Universitat de Barcelona (Spain), the Universitat Politècnica de Catalunya (Spain), the Florida State University (USA), the University of Science and Technology Beijing (China) and the Ankara University (Turkey), in collaboration with the ALBA Synchrotron.

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Synchrotron light reveals why modernist stained glass deteriorate

Stained glass is a fragile component of our Cultural Heritage since was used for the windows of buildings, and a large part of it is exposed to weathering and consequently to deterioration. The concern raised regarding the decay shown by the modernist enamelled glass has led the path to a long-term study and to the thesis presented today by Martí Beltrán González. “We are satisfied because totally new information have been obtained and, in particular, data that may help to better preserve the enamelled glass windows of this period ”, highlights Trinitat Pradell, director of the thesis.

Synchrotron light has important applications in the field of historical and artistic heritage and the Universitat Politècnica de Catalunya (UPC) group has been an ALBA user for years to carry out analyses for its research. In this case, the beamline where the experiments have been performed, MSPD, provides the use of microdiffraction technique. Stained glass samples cut into very thin sections (100 microns) have been analysed through X-rays to obtain high resolution diffraction patterns that give information about the chemical composition of the materials and enables the identification of the pigments and colorants used. The microstructure of the materials and the products formed as a result of corrosion can be detected too thanks to this synchrotron light technique.

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Image: Modernist stained glass from Museu d’Art de Cerdanyola (Les Dames de Cerdanyola) by L. Dietrich, 1888–1910, showing the characteristic green and blue enamels decay

Credit: Jordi Bonet

The ALBA Synchrotron to become a 4th generation facility

The Rector Council of the ALBA Synchrotron, counting with the participation of the Ministry of Science and Innovation and the Department of Business and Knowledge of the Generalitat de Cataluña, chaired by Minister Pedro Duque, has given the green light to start working in 2021 on the ALBA II project, an ambitious program that will transform ALBA into a 4th generation synchrotron facility upgrading the accelerator and other components and building new beamlines.

Nowadays, synchrotron facilities are experiencing an outstanding technological evolution, applying new solutions for the design and construction of accelerators, the development of X-ray detectors and the management of experimental data.

The so-called 4th generation synchrotron facilities, compared to those of the 3rd generation, produce a brighter and more coherent photon beam. When analyzing matter, they provide inaccessible capabilities as of today, in terms of resolution, detection levels and the understanding of chemical and electromagnetic properties. In addition, they offer new technological approaches to solve society’s challenges more efficiently and move towards a sustainable and smart economy in a more efficient health system.

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Image: ALBA synchrotron

Credit: ALBA

The African fly of death might also save lives

For the first time, an international team of scientists recreated in the lab the molecule that allows the tsetse fly to feed on blood. It’s a powerful yet small anticoagulant with a unique and strong binding to thrombin, the key enzyme of the coagulation pathway. X-ray diffraction measurements at two synchrotron facilities ––ALBA and ESRF–– were instrumental to understand the structure and the mechanism of action of this molecule, which suggests it is also a promising platform for designing improved anticoagulant drugs.

 In the waiting rooms of health care facilities around the world, millions of patients take anticoagulants every day. These are life-saving drugs for the treatment of cardiovascular diseases, which now are also being explored for their benefits to patients with advanced symptoms of COVID-19.

And, as incredible as it may seem, the tsetse fly, responsible for the sleeping sickness disease in humans, is now on the spotlight in the efforts to develop more powerful and safer anticoagulants. 

In a study co-authored by Bárbara Calisto, researcher at the ALBA Synchrotron, an international team of scientists has become the first to recreate in the lab the molecule that the tsetse fly uses to prevent coagulation when it bites to feed. These bites are also the entry channel for the parasite that causes sleeping sickness, a life-threatening disorder, if untreated. And the reason why the tsetse fly has been dubbed as the fly of death in Africa.

Read more on the ALBA website

Image:  Bárbara Calisto at the XALOC beamline of the ALBA Synchrotron

Credit: ALBA

“foot-2-foot” interaction sheds light on bacterial conjugation

Bacteria possess mechanisms to establish communication between cells. This is especially important in bacterial conjugation, a process that allows bacteria to share genetic material. This is often used by bacteria to transfer antibiotic resistance genes and other virulence factors to neighbor cells, increasing the antibiotic resistance spread.

Now, a research team of ALBA scientists report the structural mechanism by which two proteins, Rap and Rco, act together to regulate conjugation. Rco is a repressor of conjugation, whereas Rap binds Rco and prevents Rco-mediated conjugation repression, thus resulting in an activation of the conjugation mechanism. The main results of the study show that Rap contains a binding pocket were a short peptide can bind, producing structural changes in Rap that forces its tetramerization, releasing Rco for blocking conjugation. Tetramerization occurs through an interaction that scientists named “foot-2-foot”, which differs significantly from the model proposed for other proteins of the Rap family.

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Image: RappLS20 tetramerization, side view of the peptide-bound tetramer. The red arrows indicate the loops connecting helices H4 and H5. (C) Zoom of the area around the N-terminus of helix H4, showing the insertion of this helix into the opposite monomer. The homotetramerization caused by the foot-2-foot interactions of the NTDs of RappLS20 provides an explanation for the activation of the RcopLS20 partner. In the absence of the peptide, the NTDs are positioned such that they allow the interaction with RcopLS20. However, upon binding the signaling peptide, the NTDs shift outwards, facilitating the formation of the homotetramer, leading to a change of the interaction surface of the NTDs that is no longer available for interactions with RcopLS20

“Nano-Barber poles”: Helical surface magnetization in nanowires

Nanomagnetism is nowadays expanding into three dimensions, triggered by the discovery of new magnetic phenomena and their potential use in applications. This shift towards 3D structures should be accompanied by strategies and methodologies to map the tridimensional spin textures associated.

A new study fruit of a collaboration of researchers from two beamlines at ALBA Synchrotron (CIRCE and MISTRAL), with the participation of the Universidad Complutense de MadridIMDEA Nanociencia and the Universidad de Salamanca shows that cylindrical nanowires have at the center a magnetization aligned with the axis of the wire and at the surface a magnetization that describes helical lines as the barber poles. The helicity provides chirality to the magnetic configuration since it can be right or left-handed. Researchers found out that two adjacent magnetic domains having opposite chirality are more difficult to move than two adjacent domains with the same chirality. This result evidences the role of the chirality on the dynamics of the domain walls that might be used as a practical variable for magnetic data storage.

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Image: Figure. (Left) Barber pole illustrating the helical lines that the magnetization describes at the surface of the wires. (Right) Schematics of the configuration of the magnetization of the initial state of the nanowire together with the magnetic images before and after the application of magnetic field pulses. In the initial state, the two domain walls signaled with orange arrows separate domains with the same chirality. Note that the head-to-head or tail-to-tail domains have the same chirality in spite of having opposite signs of surface magnetization. The green arrow separates two domains of different chirality since while having the same axial orientation, the surface helicity is opposite. Magnetic field pulses of 120 mT move the walls separating domains with the same chirality but not the green wall separating opposite chirality.

How surface acoustic waves can enhance catalytic activity

An international team of researchers have studied the mechanism by which surface acoustic waves (SAW) enhance catalytic activity. They were able for the first time to measure the effect of SAW on the electronic structure of a Pt model catalyst and achieved a remarkable precision with the new experimental setup at the CIRCE beamline in the ALBA Synchrotron.

The enhancement of catalytic activity (i.e. how certain materials help interesting chemical reactions to take place easier, faster, more directed or under more desirable conditions like lower temperature) by surface acoustic waves (SAW) is an established phenomenon, but its mechanism is still not well understood. Previous experiments showed that the electronic work function of model catalyst (e.g. Platinum, Pt) change within seconds to minutes when SAW are applied. This work function change was thought responsible for the SAW induced catalytic enhancement.

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Image: Figure: Work function oscillation in a thin Pt film imaged by stroboscopic X-ray photoemission electron microscopy (XPEEM). It is caused by the elastic deformation of the surface region by a Surface Acoustic Wave (SAW) in an underlying LiNbO3 substrate, The strong oscillation in the lower area is in the bare substrate and shows a large piezoelectric ampltiude. The periodicity serves as reference for the much smaller effect in the metallic Pt film. In the inset, a line profile extracted from the white box in the upper part of the image, indicates a work function oscillation of 455 µeV amplitude in Pt.

First photons on the first mirror of LOREA

LOREA beamline has seen its first photons.

The photograph, taken in the control hutch of the beamline, shows in the computer screens the footprint of the very first photon beam on the fluorescence screen located outside the optical hutch, taken with only 2 mA of electron beam in the storage ring. Although masked, the satisfaction expressed by the three beamline scientists Massimo Tallarida (beamline responsible), Federico Bisti and Debora Pierucci is evident. This is an important milestone for the beamline, reached with very demanding operating conditions due to the pandemic situation. Congratulations to everybody that contributed to this result!

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Image: Three beamline scientists Massimo Tallarida (beamline responsible), Federico Bisti and Debora Pierucci.

Artificial double-helix for geometrical control of magnetic chirality

A study published in ACS Nano demonstrated the imprinting of complex 3D chirality at the nanoscale using state-of-the-art fabrication techniques and magnetic microscopy at MISTRAL beamline of the ALBA Synchrotron. The results prove the possible control of the magnetic configuration with geometrical morphologies displaying 3D chirality and open a new avenue on applied nanomagnetism. The research was the result of a multiple collaboration of scientists from Cambridge, Glasgow and Zaragoza Universities, the ALBA Synchrotron and the Lawrence Berkeley Laboratory.

An object is chiral if its image in a mirror cannot bring to coincide with itself as our right and left hands. Chirality plays a major role in nature, for example DNA double helix is a chiral right-handed structure. In magnetism, interactions between spins which are sensitive to chirality generate, in 2D structures with engineered interfaces, complex magnetic configurations as skyrmions that may be of future use in spintronics. In this study, researchers demonstrate the imprinting of complex 3D chirality at the nanoscale using state-of-the-art fabrication techniques and magnetic microscopy at MISTRAL. By fabricating a double helix ferromagnetic structure, magnetic domains were created having the same chirality of the double helix. Moreover, if the geometrical chirality was inverted in the course of the fabrication of the strand, then, the chirality of the magnetic domains was also inverted. At the location were both magnetic chiralities meet, a confined 3D magnetization was evidenced. The ability to create chiral 3D structures with nano patterning enables the control of complex topological magnetic states that might be important for future materials in which chirality provides a specific functionality.

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Image: Figure: a) 3D-printing of a cobalt nano-helix by FEBID. After injection of Co2(CO)8 into the chamber of a scanning electron microscope (SEM) using a gas injection system (GIS), the focused electron beam (in green and magenta) alternatively exposes the two helix strands. b) Coloured SEM image of the nanostructure under investigation, consisting of two double-helices of opposite chirality joined at the tendril perversion marked *. Scale bar 250nm, c) XMCD image of the double helix studied, which changes geometric chirality at *. Image at zero field, after application of a saturating field H along the axis as indicated. D) XMCD image of the double-helix under study in the as-grown state. Scale bars in c) and d) 200 nm.

Understanding how the taxanes antitumoral drugs modulate cell microtubules

Researchers have found that addition of paclitaxel (a type of antitumoral drug) to microtubules alters their structure. This compound modulates the material properties of microtubules by converting destabilized growing microtubule ends into regions resistant to depolymerisation, eventually leading to cell death. Results were obtained at the NCD beamline of the ALBA Synchrotron.

Paclitaxel, one of the most commonly used antitumoural drugs, modulates microtubules, the biopolymers responsible for many essential cellular functions including cell division, movement and intracellular transport. This kind of drugs target tubulin subunits, the main microtubule proteins, and interfere with their dynamics, which can have the effect of stopping a cell cycle and can lead to programmed cell death or apoptosis.

Read more on the ALBA website 

Image: Microtubule X-ray fiber difractogram in presence of Paclitaxel.

Credit: NCD-SWEET beamline at ALBA Synchrotron

Accoustic spin waves: towards a new paradigm of on-chip communication

For the first time researchers have observed directly sound-driven spin waves (magnetoacoustic waves) and have revealed its nature.

Results show that these magnetization waves can go up to longer distances (up to centimeters) and have larger amplitudes than the commonly known spin waves. The study, published in Phys. Rev. Lett., is carried out by researchers from the University of Barcelona (UB), the Institute of Materials Science of Barcelona (ICMAB-CSIC), and the ALBA Synchrotron, in collaboration with the Paul-Drude-Institut in Berlin.

Researchers have observed directly and for the first time magnetoacoustic waves (sound-driven spin waves), which are considered as potential information carriers for novel computation schemes. These waves have been generated and observed on hybrid magnetic/piezoelectric devices. The experiments were designed by a collaboration between the University of Barcelona (UB), the Institute of Materials Science of Barcelona (ICMAB-CSIC) and the ALBA Synchrotron. The results show that magnetoacoustic waves can travel over long distances -up to centimeters- and have larger amplitudes than expected.

>Read more on the ALBA website

Image: TOP: A propagating and a standing magnetization wave in ferromagnetic Nickel, driven by magnetoelastic coupling to a surface acoustic wave in a piezoelectric LiNbO3substrate. The images combine line profiles (color indicating the local magnetization direction) at different delay times between the probing X-ray pulse and the electrical SAW excitation.
BOTTOM: Scheme of the strain caused by the surface acoustic waves (SAWs) in the piezoelectric (in green color scale) and magnetic modulation in the ferromagnetic material (in orange-cyan color scale).

Ten years at the service of the society and its challenges

On 22nd March 2010, ALBA was inaugurated becoming one of the most important scientific infrastructures of Spain.

Since then, its synchrotron light has been a great ally for numerous advances in a huge range of scientific fields, such as biomedicine, materials science, nanotechnology or archaeology. The ALBA Synchrotron represents a formidable return of knowledge, development and well-being for society.
Cerdanyola del Vallès, 23rd March 2020 10 years have passed since the inauguration of ALBA, the Spanish synchrotron light source. InMarch 2010, it was celebrated the launch of an unprecedented scientific project whose aim was becoming an essential tool for science and technology. Ten year later, ALBA has far exceeded its initial expectations, also being an international reference among worldwide light sources. It is currently under a continuous growth process byinstalling new equipment and updating its instrumentation to meet both present and future scientific challenges. In particular, ALBA is helping in the fight against COVID-19 to advance in the knowledge of the virus and in the development of vaccines and treatments.

The number of synchrotron light users in Spain has reach, from the initial 200 at the time of the project approval, to more than 5,000 users, almost half of them international; as well as more than 50 private national and international companies. In total, ALBA has provided synchrotron light for research groups belonging to 1,850 institutions from 45 different countries. The result has been more than 1,500 experiments performed that have been reflected in around 1,100 scientific publications.
Currently, the ALBA Synchrotron has 8 beamlines and 5 more are under construction, all equipped with different techniques for analyzing matter at an atomic and molecular level thanks to the high quality of the synchrotron light produced. Since the beginning, 37,722 hours of light have been generated. In this time, the electrons inside the accelerators would travel 2.7 million times the distance from Earth to the Sun!

>Read more on the ALBA website.

Imaging how anticancer compounds move inside the cells

Chemotherapeutics are key players in the clinical setting to fight most types of cancer, and novel chemicals hold the promise to facilitate new and unique intracellular interactions that modulate the cell machinery and destroy the tumour cells. Equally necessary are new tools that enable the unequivocal location and quantification of such molecules in the intracellular nano-space, so that their therapeutic action is fully understood.

Researchers from IMDEA Nanociencia, the ALBA Synchrotron, the European Synchrotron Radiation Facility (ESRF) and the National Centre for Biotechnology (CNB) have developed a new family of organo-iridium drug candidates about a hundred times more potent than the clinically used drug cisplatin.
In order to understand the therapeutic potential of the compound, it is mandatory to accurately localize its fate within the cell ultrastructure with minimal perturbation. To this aim researchers have correlated on the same cell, for the first time, two 3D X-ray imaging techniques with a resolution of tenths of nanometers: cryo soft X-ray tomography, at MISTRAL beamline at ALBA Synchrotron, and cryo X-ray fluorescence tomography, at ID16A beamline at ESRF. These techniques help elucidate the 3D architecture of the whole cell and to reveal the intracellular location of different atomic elements, respectively.

>Read more on the ALBA website

Comprehensive study of strontium hexaferrite platelets

Researchers have synthesized and studied by a combination of soft X-ray techniques platelets of strontium hexaferrite allowing them to establish the differences and similarities between their synthesized nanostructures and commercial powders.

Most of the experiments have been performed within a collaboration among three beamlines of the ALBA Synchrotron.
Ferrites are ceramic materials usually made of large proportions of iron oxide (Fe2O3, rust) blended with small proportions of other metallic elements. These materials do not conduct electricity because they are insulators; and they are ferromagnetic, which means they can easily be magnetized or attracted to a magnet.

Strontium ferrites (SFO, SrFe12O19) in particular have a large magnetocrystalline anisotropy that gives it a high coercitivity, meaning that it is difficult to demagnetize. Since its discovery in the mid-20th century, this hexagonal ferrite has become an increasingly important material both commercially and technologically, finding a variety of uses and applications because of its low cost and toxicity. SFO has been used for permanent magnets, recording media, in telecommunications, and as a component in microwave, high-frequency and magneto-optical devices. Also, because they can be powdered and formed easily, they are finding their applications into micro and nano-types systems such as biomarkers, bio diagnostics and biosensors.

>Read more on the ALBA website