Invited Lecturers Abstracts

Title: Hyperspectral XEOL imaging at the nanoscale

Abstract: Owing to the sensitivity (i.e., signal to background ratio), temporal and spatial resolutions, pulsed synchrotron X-ray nanobeams are promising tools for correlative light and X-ray chemical analysis of functional nanodevices. However, their full potential is ultimately dictated by our ability to detect multiple property-function relationships taking place at the nanoscale in the spatial and time domains. Only a combination of high-resolution X-ray excited optical luminescence techniques can provide a comprehensive understanding of their complex functionalities. Here we describe how a multimodal hard, polarized and pulsed X-ray nanoprobe addresses fundamental questions in nanowire research about the carrier dynamics, relaxation, recombination and light polarization within single wires at the nanoscale. Selected topics ranging from cluster formation, dopant segregation, and phase separations to quantum confinement effects are investigated with sub-100 nm spatial resolution and sub-50 ps temporal resolution. This approach opens also new avenues for structural, composition and optical studies with broad applicability in materials science.

Title: Understanding energy storage materials with in situ coherent diffraction imaging

Coherent diffraction continues to develop into a mature technique capable of imaging single nanoparticles and thin film grains in a variety of in-situ environments. Its unique sensitivity to structural perturbations, and dislocations, has made it the premier imaging tool for crystalline specimens with sizes of 100 nm to 1 micron. In this talk, I will introduce coherent diffraction in both Bragg and transmission geometries and then spend the majority of the time on applications of the techniques to two energy storage systems that share many similarities in their underlying thermodynamics: advanced battery cathodes and hydrogen storage materials.

Title: Opportunities for Soil and Plant Scientists at the Sirius-LNLS CARNAÚBA Beamline

Optimal performance of soil-plant systems is essential for high agricultural productivity and conservation of natural ecosystems. The element specificity of synchrotron X-ray techniques provides unprecedented mechanistic information about chemical and structural properties of soils and plants, which serves as a foundation for improved strategies for managing natural resources. The CARNAÚBA beamline is designed with unique and complementary analytical capabilities of that are well suited for studying soils, plants, and soil-plant interfaces.  Soils themselves comprise complex assemblages of minerals, organic matter, non-crystalline inorganic solids and microorganisms; and plant roots alter the chemical and microbial properties of the root-soil interface, i.e., the rhizosphere. Functional insights to such complex, multi-component systems are enhanced by characterization of the same sample areas with multiple, spatially resolved analytical techniques. For multi-element imaging, the two experimental stations at CARNAÚBA with different beam spot sizes will facilitate rapid imaging of larger sample areas or volumes to define overall spatial patterns of chemical elements, followed by high-resolution imaging of chemical substructure on features of interest using a smaller beam (down to 30 nm). Moreover, heterogeneous spatial patterns of chemical elements in soils and at soil-root interfaces enhances identification of less abundant chemical species of a given element by micro- or nano-scale X-ray absorption spectroscopy (µ-XAS, n-XAS). Similarly, in plant sciences, access to X-ray beams of multiple spot sizes at a single beamline will enable rapid and high-resolution imaging of important biological elements at tissue, cellular, and sub-cellular levels. The CARNAÚBA beamline also covers a broad energy range from tender to hard X-rays. Soils contain numerous chemical elements. Ideally, all elements of concern to a particular problem could be imaged simultaneously to augment chemical speciation analysis via knowledge of element co-localization. At low-energies, the more abundant soil matrix elements (silicon and aluminum) can be imaged along with important plant nutrients – especially phosphorus, sulfur, potassium, and calcium. Remarkably, the beamline is also designed for imaging and spectroscopy of heavier soil-matrix elements and biological micronutrients (e.g., iron, manganese, zinc, copper, selenium), and toxic metal(loids) of environmental concern in soils, water, and the food chain (e.g., arsenic, mercury, cadmium and lead). Finally, spatially resolved diffraction should identify mineral phases at matrix contents far below those needed for detection by bulk-sample diffraction. The CARNAÚBA beamline will provide complementary X-ray techniques that are of great value for addressing a broad range of problems in soil and plant sciences.

Title: New challenges in nanomaterials characterization to bridge the “size gap”

Historically, spectroscopic techniques represent a powerful tool for electronical or chemical characterization, being a complementary method of image-based techniques to create the strongest scientific description of physical or biological systems. However, the combination of those strategies results not enough for actual demands in scientific research, in particular at the Nanoscience field. The emerging new instrumentation based on nano-spots of X-rays using synchrotron sources, as the Carnauba beamline at SIRIUS synchrotron, represent new opportunities for new rational answers and even revisit old and relevant fields. In this presentation we will present few examples of nanomaterials characterization, like nanoparticles, nanofibers, atomic quantum clusters, interphases, etc, analyzing the possible impact of the new instrumentation for characterization at the Nanoscience field.

Title: Ancient life comes to light, new approaches for old questions

Study of fossils allow paleontologists to know both biological and ecological characteristics of ancient life, but also its biodiversity and several times, the geological processes necessary to preservation. The fossil record is very odd and fragmented, some fossils can be very rare museum specimens, some preservation processes are exceptional occurring few times in the geological record, or fossils can come from remote and difficult to access localities, defying paleontologists to look for methods of study that preserve the specimen integrity without losing of data quality. Modern paleontology lead with issues beyond classic descriptions of organisms and interpretations about its ecological relationships or their position in geological timescale. Nowadays, fossils are valuable pieces in the puzzle of life’s history, and its insertion in an ecological and evolutionary context, requires the ability to integrate diverse sciences i.e., geology, biology, chemistry, physics, and so on, this increasingly interdisciplinary area is reaching a more sophisticated level of knowledge by the integration of data from several areas. In recent years, several approaches based on Paleometry techniques have been contributed to understand the ancient life, solving old questions and raising new ones, these approaches using quantitative and/or qualitative non-destructive or less invasive analytical techniques has proved its relevance in Paleontology. Imaging and 3D modelling based on synchrotron micro CT can reveal hidden fossil structures inside rock matrix, geochemical techniques as X-ray Fluorescence (XRF), X-ray Diffraction (XRD) and, X-ray absorption near edge structure (XANES) of microfossils, fossil plants, animal carcasses, or preserved soft tissues,  have allowed the characterization of morphology, chemistry, physiology, and ecology of extinct organisms and the understanding of fossilization processes thorough the understanding of the geobiological mechanisms and interaction of decaying organisms and its surrounding environment including interaction with microorganisms.

Title: Glycans and metals from marine invertebrates to mammalians: ancient regulators of cell fate in health and disease

Glycosaminoglycans are ancient molecules found from early invertebrates to humans that have evolved in complexity through time. In particular, they interact with many metals and co-operate to regulate diverse biological processes, such as cell growth, differentiation, and migration in development and disease. Our work focuses on how glycosaminoglycans regulate metallic elements’ activity within mammalians systems and how this process is disrupted in cancer. We also study how ancient glycosaminoglycans produced by marine invertebrates present antitumoral properties in mammalian systems, bringing to light an evolutionary link on how evolving organisms dealt with multicellularity in continuously and profoundly changing environments.  Our perspectives for the new light source, Sirius, include higher magnification imaging of isolated mammalian normal and cancer cells, as well as marine invertebrate cells, in order to unveil subcellular metals distribution. We also intend to develop techniques to couple protein and glycans imaging with multi-elemental imaging in the same sample, allowing for more robust correlations in biological systems.

Title: A materials science view of coherent synchrotron techniques.

In this seminar we discuss current challenges in coherent scattering techniques (CDI, ptychography, etc..) from a materials science perspective. Besides the direct application of coherent X-ray beams in isolated objects, several limiting issues still need to be overcome in order to bring such techniques to common grounds with respect to Transmission Electron Microscopy (TEM) and Scanning Probe Microscopy (SPM) results. In particular, we discuss scientific cases of objects with large strain fields, the observation of lattice mismatch in novel two-dimensional materials systems and the use of anomalous (resonant) conditions, which require positional stability over selected energy ranges.

Title: AuPd bimetallic nanoparticles: correlations between composition, local structure and catalytic activity

Bimetallic nanoparticles may present different and superior catalytic properties to their monometallic constituents but are much more complex and difficult to characterize systems. The understanding of the effects of compositional variation (bulk and surface), morphology and possible restructurings suffered by bimetallic nanoparticles under reaction conditions, as well as correlations with their catalytic properties, is fundamental for the design of increasingly active and selective catalysts. In this seminar we will discuss the studies with bimetallic nanoparticles of AuPd composition and varied structure against oxidation and hydrogenation reactions. The samples were prepared and characterized by X-ray absorption (XAS), X-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) techniques. Samples with structure ranging from homogeneous alloys to core-shell structures were obtained. For the oxidation of benzyl alcohol an increase in catalytic activity of up to five times was observed after the calcination of the AuPd alloy type catalysts, with higher activity for palladium rich samples. When preparing core-shell Au @ Pd type catalyst, the amount of palladium required for maximum activity is much lower. For hydrogenation reactions, amounts as low as 1% palladium are enough to develop active and selective catalysts. All systems were compared with monometallic catalysts.

Title: Nanophotonic materials for energy harvesting and storage: looking closer with Carnauba coherent beam

New applications of different photonic materials arise every year, especially for harvesting and storing energy. For example, applications like photosynthesis at night, photodynamic therapy in the dark and bioimaging without in-situ excitation sources (or radioactivity) could sound controversial a few years ago, but can be achieved now using light storage compounds, e.g. persistent luminescence materials. These materials store energy in defects releasing it with the aid of thermal energy. On the other hand, applications very well established like solar energy harvesting from up- and down-conversion materials urges for more efficient processes. To optimize these processes, as well to think in new applications for photonic materials, it is important to look deep into the materials. Nano and micro domains are fundamentals for the emitting, absorption and energy transfer processes. The Carnauba beamline will aid the understanding and optimization of these phenomena allowing us to investigate the material domains during the electronic processes with e.g. coupled micro and nano XEOL, XRD, XAS and XRF.

Title: X-ray spectrometry in agricultural sciences

In this presentation, we will approach some uses of X-ray spectrometry in agricultural sciences. We will outline the state-of-the-art for chemical speciation and elemental mapping in plant and soil samples. Currently, XRF allows tracing the movement of elements trough plant tissues, which is an alternative to the use of radioisotopes. Additionally, XAS can reveal the interaction between fertilizers and herbicides in tanks and probe the chemical environment of nutrients within seeds and plants. The main challenges in the field consist in developing sample environments for in situ measurements, coupling of techniques and dealing with radiation damage during in vivo analysis.

Title: Nanoparticles-cell interaction: intracellular dynamics and cell structure response probed by x-ray microscopy

The understanding of the mechanisms behind the interaction of nanoparticles and living cells is the cornerstone for the development of future nanomedicine. Improvements on nanoparticles efficiency and their safety regarding applications on diagnostics and therapeutics can fundamentally be traced back to the nanoparticle distribution within a cell. However, probing nanoparticles internalization and trafficking into cells with subcellular resolution remains limited by conventional 2D imaging or low-resolution 3D information. At the same time, the recent development of x-ray microscopes has pushed x-ray 3D imaging down to an isotropic nanometer resolution is now possible. In this way, the Carnaúba beam line and their two experimental stations, named Tarumã and Sapoti, will represent a turning point for nanoparticle visualization and characterization. Multiple techniques such as XRF, XAS and specially ptychography will provide 3D chemical and structural analyses of in situ nanoparticles; there is inside a cell or tissue. At this work, we discuss the perspectives for studying nanoparticles-cells systems using Ptychographic Tomography (PXCT) at the Carnaúba beamline how it will allow the high-resolution imaging of multiple nanoparticles at various cell incubation stages unveiling the fundaments behind both nanoparticle uptake and long-term exposure to advanced nanomedicines.

Title: Development of tools to label and image proliferative cells and neurons using X-ray imaging techniques with Synchrotron Radiation

Zebrafish have an exquisite capacity to regenerate damaged neurons following spinal cord injury (SCI). The activation of quiescent ependymal cells that serve as endogenous stem cells is required to initiate neural regeneration in zebrafish, but little is known about the cellular mechanisms these cells undergo or the signaling pathways that activate them. Therefore, understanding the cellular behavior and manipulating signaling pathways that activate the stem/progenitor cells holds great promise in the treatment of SCI. The aim of this project is to develop tools to label and image newborn neurons during the regenerative process in zebrafish using X-ray imaging techniques with Synchrotron Radiation (SR), such as X-ray Fluorescence microscopy (XFM) and X-ray Computed Tomography (XRCT). More specifically, this project involves the development of chemical probes that label proliferative cells with heavy metals or other chemical elements and a technique to label specific neurons with nickel, allowing the identification of newly formed neurons during the regenerative process using the X-ray imaging techniques with SR mentioned previously.

Title: Testing biogenicity of ancient rocks – How nanometric resolution can solve these problems.

Microbial life may have colonized Earth already before 3.5 billion years. However, no fossil evidences from this period have been universally accepted so far, and any evidence of life around these ages is contestable or dubious. Samples related to the earliest signs of life on Earth are rare and often require non-destructive techniques, as well as the highest resolution as possible. One way to detect or support biogenicity in ancient rocks is to correlate the distribution patterns of trace elements and minerals commonly associated to modern microbial metabolisms with the morphological biosignatures. Here, we present some of these approaches to solve questions about biogenicity using synchrotron-based X-Ray techniques, such as X-ray Fluorescence, X-ray absorption and X-ray diffraction, in which nanometric resolution is of prime importance. The examples of applicability include 1 billion years old Brazilian stromatolites, in which traces of a putative microbial ecological interactions may have been preserved, as well as a candidate of the oldest record of life on Earth consisting of putative preserved biofilms in rocks of 3.7 billion years old from Isua Greenstone Belt, Greenland.

Title: Coherent X-ray diffraction imaging unravelling structure-activity relationships of gold nanocrystals under CO oxidation conditions

Chemical properties of catalytic materials are dependent on dynamic changes of the three-dimensional structure of the catalysts as well as the reactive environment. The identification of the active sites formed under reaction conditions remains a great challenge. Besides, defects and lattice strain dynamics of nanocrystals directly tuned their catalytic properties. To reveal the relationship between catalysts structure and activity, the study of catalysts under operando conditions is crucial. Bragg coherent X-ray diffraction imaging (Bragg CDI) provides a unique opportunity to follow in 3D under realistic reaction conditions the strain and defects dynamics in the surface and inner core of the nanomaterials. In this talk, I will present our in situ/operando Bragg CDI investigations of gold catalysts during CO oxidation. Under the catalytic reaction conditions, we investigate the defects dynamics of gold nanocrystals with twin domains and show the in situ formation of a nanotwin network that correlates with the catalytic properties. Besides, we follow at the single nanoparticle-level, the highly dynamic 3D strain distribution during the hysteresis phenomenon occurring through CO oxidation reaction cycles.

Title: Using synchrotron-based techniques to probe microbe-mineral interaction: from life detection to biotechnological applications.

Microorganisms were the first life forms to appear on the planet and nowadays they are present on almost all environments, even the most extreme ones. They have a large variety of metabolisms and adaptative strategies to survive, being responsible for global changes on the planet. A special group of microorganisms are of those capable of interacting with inorganic species to obtain energy, to reduce the toxicity of the medium and others. This area of knowledge, called biogeochemistry, geomicrobiology, or also microbe-mineral interactions, can be important, for example, to study ancient or modern registers of life, since microorganisms are responsible for the precipitation of biogenic minerals, and to the development of biotechnological applications, like biomining, bioprecipitation of functional nanoparticle, bioremediation of contaminated environments, etc. Synchrotron-based techniques play an important role on the study of the formed species as well as on the understanding of the processes involved. In this presentation, it will be showed a general overview of this field and the importance of some spectroscopic techniques, focusing on some of the problems that are being carried out using the facilities of LNLS and which will take a leap further with Sirius.

Title: Coherent Diffractive Imaging techniques in biological systems.

Coherent Diffractive Imaging (CDI) is a collection of techniques dating back to 1999 when a simple inorganic mask was imaged proving the concept. Since then, significant developments have been done branching on multiple techniques such as ptychography, plane wave-CDI, Bragg-CDI, among others. Today, those techniques are ever improving and had already proved as a viable tool with tridimensional imaging capabilities (tomographic imaging) a resolution between optical and electron microscopy, thus working as a bridge between the two. Within this context, biological samples are notorious for being highly hierarchical and to present a strong relationship between structure and function. Such a structured sample is typically tridimensional in space and beneficiates from both the tridimensional imaging of x-ray and the resolution of the CDI techniques. Here, we discuss the perspectives for studying biological samples using CDI. We will present some of the main results found in the literature that would have a significant impact on biological imaging experiments. Also, we shall present some of the current developments on sample preparation for the proper design and execution of tridimensional CDI-based biological imaging at the Carnaúba beamline.

Title:  Ptychographic reconstruction using multi GPUs

In this talk, we will describe the main challenges for ptychographic reconstruction using an array of GPUs within the context of high-performance computing. The restoration algorithms EPIE and MPIE will be presented, with a focus on the distribution of data. A reconstruction pipeline for SIRIUS will be discussed, presenting algorithmic perspectives for the beamline Carnauba.

Title: The CARNAÚBA beamline: status and future opportunities

The status of the CARNAÚBA beamline will be presented, as well as future scientific opportunities.

Title: Sirius status