Metal pollutants cause metabolic alterations in algae

Contamination by metals like cadmium or mercury is considered a serious threat to the environment and human health. Several human activities such as mining, metallurgy industry, and extensive use of mineral fertilizers are the main sources of ongoing metal pollution in numerous ecosystems. This environmental risk is potentiated by bioaccumulation and trophic chain biomagnification phenomena, which are associated with the long persistence of toxic metals in the polluted ecosystems. Aquatic and soil ecosystems affected by runoffs loaded with toxic metals are particularly vulnerable, where primary producers photosynthetic organisms (phytoplankton and soil microalgae) represent the first stage of pollution build-up. Knowledge about mechanisms of toxicity in these organisms is essential for appropriate assessment of environmental risks.

Researchers from the Plant Physiology Laboratory of the Department of Biology, also affiliated with the Research Centre for Biodiversity and Global Change, at the Autonomous University of Madrid (UAM), have discovered the major changes of biomolecules caused by cadmium and mercury in the model green microalga Chlamydomonas reinhardtii.

The use of synchrotron technology at MIRAS beamline was a valuable tool and has made it possible to analyze in detail variations in the biomolecular pattern caused by heavy metals at levels of resolution rarely described before. “Among the cellular components that readily changed upon metal treatments, we detected alterations in the lipid composition by synchrotron light infrared spectroscopy at ALBA, which corresponded to accumulation of neutral lipids and increased fatty unsaturation” specifies Ángel Barón, scientist at UAM.

Read more on the ALBA website

Image: Electron transmission microscopy of Chlamydomonas reinhardtii cells to show alterations caused by cadmium and mercury. The pyrenoid (p) looks aberrant, with proliferation of lipid vesicles (green arrowhead) and starch grains (s). Metals also triggered the appearance of autophagy vesicles (red arrowhead). Right: image of Chlamydomonas reinhardtii 

Credit: image of Chlamydomonas reinhardtii  Wikimedia Commons.

Tuning the magnetic anisotropy of lanthanides

The magnetism of lanthanide-directed nanoarchitectures on surfaces can be drastically affected by small structural changes. The study carried out in a collaboration between researchers from IMDEA Nanociencia and BOREAS beamline at ALBA reports the effect of the coordination environment in the reorientation of the magnetic easy axis of dysprosium-directed metal-organic networks on Cu(111). The authors show that the magnetic anisotropy of lanthanide elements on surfaces can be tailored by specific coordinative metal-organic protocols.

Recent findings have highlighted the potential of lanthanides in single atom magnetism. The stabilization of single atom magnets represents the ultimate limit on the reduction of storage devices. However, single standing atoms adsorbed on surfaces are not suitable for practical applications due to their high diffusion, i.e., low thermal stability. The next step towards more realistic systems is the coordination of these atoms in metal-organic networks.In 4f elements, the spin-orbit coupling (SOC) is larger than the crystal field, which might result in higher anisotropies. Furthermore, the crystal field acts as a perturbation of the SOC and can be tailored to increase the anisotropy by choosing an appropriate coordination environment. The strong localization of the 4f states reduces the hybridization with the surface, increasing the spin lifetimes, which is crucial, since a long magnetic relaxation time is mandatory for technological applications.

Read more on the ALBA website

Image: Cover picture showing the structure of the Dy-TPA network where C, H, O and Dy atoms are represented by black, red and green balls, respectively, the tilted orientation of the magnetic easy axis is represented by green arrows. 

Credit: ALBA

A new way of controlling skyrmions motion

A group of researchers from France has been able to create and guide skyrmions in magnetic tracks. These nanoscale magnetic textures are promising information carriers with great potential in future data storage and processing devices. Experiments at the CIRCE-PEEM beamline of the ALBA Synchrotron enabled to image how skyrmions move along tracks written with helium ions.

Magnetic skyrmions are local twists of the magnetization, considered as units (bits) in new magnetic data storage devices. They were named after British physicist Tony Hilton Royle Skyrme, who described these whirling configurations in the 80’s. But it was not until 2006 that there was evidence of their existence.

Skyrmions are of great interest for the scientific and industrial community as they could help finding more efficient ways to store and process information in our computers. They can be manipulated with lower electrical currents, opening a path for being used as information carriers.

But skyrmions are difficult to control. They do not move in straight lines when current is injected but naturally drift sideways, “killing” themselves. This is known as the Skyrmion Hall effect. In order to be used in devices, they need to be moved and controlled in a reliable way.

A group of researchers led by Olivier Boulle from SPINTEC (Grenoble, France) has a wide experience on the subject. They already reported in 2016 the first observation of magnetic skyrmions under conditions appropriate to the industrial needs, with experiments done at the ALBA Synchrotron.

Now, they have found a way to create and guide skyrmions in racetracks: by irradiating magnetic ultrathin layers with helium ions. This method enables to locally tune the magnetic properties to the desired point without introducing defects in the layer.

The samples were prepared and its magnetic properties were locally modified by helium ions irradiation to create the tracks. Later, they were characterized with different techniques to ensure the preparation was consistent. At the CIRCE beamline of the ALBA Synchrotron, using the PEEM photoemission electron microscope, they were able to image how skyrmions move along the tracks when receiving current pulses. Results were confirmed with magnetic force microscopy and micromagnetic simulations.

Read more on the ALBA website

Image: Micromagnetic simulation showing skyrmion motion along the irradiated racetrack. The irradiated racetrack confines the skyrmions within and they move with nanosecond (ns) current pulses along the track edge without being annihilated, thereby deminishing the Skyrmion Hall Effect (SkHE) (current densities in the parentheses are in A.m-2).

Researchers discover the origin of calcium in human bones

A study from several Italian institutions and the ALBA Synchrotron suggest crystalline calcium carbonate as a precursor of hydroxyapatite in the process of bone formation. Since hydroxyapatite is a mineral constituting 70% of the mass of bone, these findings may have potential applications in the development of new therapeutic approaches in bone cancer. Thanks to the MISTRAL beamline at ALBA, researchers were able to create a 3D tomogram of human cells and visualize calcium depositions inside them.

Stem cells are “non-specialized” cells that can differentiate (transform) into a specific type of cell with a specific function. To become bone cells, stem cells need to “learn” how to take calcium to form the bones. This is related to biomineralization, a process by which living organisms produce minerals, often to harden or stiffen existing tissues. Calcium is known to be found in bones in the form of hydroxyapatite, which is a naturally occurring mineral form of calcium apatite and represents approximately 70% of the mass of bones.

In human cells, biomineralization culminates with the formation of hydroxyapatite, but the mechanism that explains the origination inside the cell and the propagation of the mineral in the extracellular matrix remains largely unexplained, and its characterization is highly controversial, especially in humans.

An interdisciplinary research team, formed by several Italian institutions and the ALBA Synchrotron, used synchrotron-based techniques to characterize the contents of calcium depositions in human stem cells induced to differentiate towards bone cells (osteoblasts). They compared the results for cells at 4 and 10 days after the osteoblastic induction.

Rad more on the ALBA website

Image: Model of early phases of biomineralization showing the localization and composition evolution of Ca compounds during the early phases of osteogenic differentiation. The figure reports also the spectra of Calcite and hydroxyapatite.

Unravelling the history of 15th Century Chinese porcelains

Researchers from French and Spanish Institutions used the combination of two synchrotron light characterization techniques to study Chinese blue-and-white Ming porcelains. They were able to identify the firing temperature by determining the porcelain’s pigments and the reduction-oxidation media conditions during their production. The approach they used can also be applied on a broad range of modern and archaeological ceramics to elucidate their production technology.

Pottery is found at the majority of archaeological sites dating from the Neolithic period, when first human settings appear, onwards. Which makes it a major focus of study in archaeological science.  The study of style and production of ceramics is central to the historical reconstruction of a site, region and period.

More specifically, ceramic technological studies look to reconstruct the production technology of ceramics, by determining the selection and preparation of the raw materials, the formation of ceramics, treatment and decoration of the ware’s surface and the firing atmosphere. All of this is possible thanks to the scientific techniques available nowadays.

In a recent publication, researchers from French and Spanish Institutions used the combination of two synchrotron light characterization techniques to study Chinese blue-and-white Ming porcelains. These characteristic porcelains, whose production flourished around the 14th century, are decorated under the glaze with Cobalt-based blue pigments that provided their distinctive blue decorations and produced during a one-step firing at high temperatures.

They were able to identify the firing temperature by determining the porcelain’s pigments and the reduction-oxidation media conditions during their production. The approach they used can also be applied on a broad range of modern and archaeological ceramics to elucidate their production technology.

Read more on the ALBA website

Image: Porcelain Jar with cobalt blue under a transparent glaze (Jingdezhen ware). Mid-15th century

Credit: Metropolitan Museum of Art.

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. 

Read more on the ALBA website

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.

Read more on the ALBA website

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.

Read more on the ALBA website

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.

Read more on the ALBA website

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.

Read more on the ALBA website

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.

Read more on the ALBA website

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.

Read more on the ALBA website

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.

Read more on the ALBA website

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!

Read more on the ALBA website

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.

Read more on the ALBA website

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.