Optische Kohärenztomographie mit extrem ultravioletter Strahlung

In dieser Doktorarbeit wird das Konzept und die Realisierung von laserbasierter optischer Kohärenztomographie im extrem ultravioletten (XUV) Spektralbereich - kurz XCT - behandelt. XCT ist eine dreidimensionale Mikroskopiemethode, welche eine axiale Auflösung von wenigen Nanometern erreichen kann. Es wurde ein XCT-Modell zur Rekonstruktion der axialen Probenstruktur entwickelt, welches die Wechselwirkung zwischen XUV-Licht und der zu untersuchenden Probe beinhaltet. Das neuartige Mikroskopieverfahren, welches bisher nur an Synchrotronquellen demonstriert wurde, konnte mit einer laserbasierten XUV-Quelle im Labormaßstab umgesetzt werden. Durch die Erzeugung hoher Harmonischer von infraroter Laserstrahlung konnte eine breitbandige XUV-Quelle mit ausreichend hohem Fluss im Siliziumtransmissionsfenster von 30eV - 100eV realisiert werden. Es wurde ein komplett überarbeitetes und an die Laserquelle angepasstes XCT-Mikroskop entworfen und aufgebaut, sodass XCT nun routinemäßig eingesetzt werden kann. Die erreichte axiale Auflösung ist mit ca. 30nm mit der am Synchrotron erreichten Auflösung von etwa 20nm vergleichbar. Des Weiteren wird ein neuartiger eindimensionaler Phasenrekonstruktionsalgorithmus vorgestellt, der in der Lage ist, die Probenstruktur aus dem XCT-Signal eindeutig zu rekonstruieren, was bisher nicht möglich war. Durch XCT-Messungen wurde eine dünne Schicht in einer Probe gefunden, die nicht Teil der ursprünglich geplanten Probenstruktur war. Die Existenz dieser Schicht und damit die XCT-Messung konnte durch eine Messung mit einem Transmissionselektronenmikroskop bestätigt werden. XCT in der realisierten Form besitzt Anwendungsfelder bei der dreidimensionalen Untersuchung von (Mehrlagen-)Beschichtungen beispielsweise von optischen oder XUV-Spiegeln, funktionalen axialen Strukturen in Solarzellen oder axial strukturierten Halbleitern wie beispielsweise Graphen-basierter Elektronik. Auch die Abbildung biologischer lateral homogener Membranen ist denkbar

Effect of lead on proliferation, oxidative stress and genotoxic damage of 3T3-L1 fibroblasts

Lead (Pb) is an environmental and industrial contaminant that still represents a public health problem. In this paper, we investigated the effect of Pb on proliferation, lipid peroxidation and the number of micronucleated cells in exponentially growing 3T3-L1 fibroblasts, a cell line previously used to evaluate different environmental contaminants. We found that Pb (10 μM or higher) was able to inhibit proliferation of exponentially growing cells after 24-h treatment, which was evaluated by the MTT assay and cell counting in Neubauer chamber, but cell survival was not affected according to the trypan blue exclusion assay. On the other hand, Pb was able to increase lipid peroxidation and the number of micronucleated cells, which are indicative of oxidative stress and genotoxic damage respectively. We also found that removal of Pb after 24-h treatment allowed cells to recover proliferation. Our results indicate that Pb was able to induce oxidative stress and genotoxicity in this cell line under standardized conditions, which supports the involvement of Pb in similar effects observed in human exposed to this heavy metal. In addition, Pb inhibits proliferation of exponentially growing fibroblasts but cells resume proliferation after removal of this metal, which suggests that it is important to move away Pb-exposed individuals from the source of contamination.Fil: Martini, Claudia Noemí. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; ArgentinaFil: Sosa, Fernando Nicolás. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fuchs, Julio Silvio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Vila, María del Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; Argentin

Combined effects of goethite nanoparticles with metallic contaminants and an organophosphorus pesticide on Eisenia andrei

The effects of mixtures of nanoparticles (NPs) and other chemicals have been poorly studied in terrestrial invertebrates. In this study, we investigated the effects of binary mixtures of goethite (α-FeOOH) NPs and metallic (Cd and Pb) or organic (chlorpyrifos, CPF) contaminants in Eisenia andrei earthworms. We used the filter paper contact test to evaluate (i) the uptake of NPs in organisms exposed to the mixtures of NPs+Metals and NPs+CPF and (ii) the potential effects of the mixture of NPs+CPF on the CPF-induced inhibition of the biomarker enzymes acetylcholinesterase (AChE) and carboxylesterases (CES). We used the artificial soil test to deepen the study on joint effects of NPs+CPF. All compounds were applied separately and in binary mixtures. In the single exposure treatment, Fe levels decreased significantly in organisms exposed to NPs on filter paper, suggesting systemic effects aimed at eliminating Fe incorporated through NPs. Conversely, earthworms exposed to binary mixtures showed Fe levels similar (NPs+Metals) to or higher (NPs+CPF) than controls. The earthworms single exposed to NPs presented no changes in AChE and CES activities. In the artificial soil test, the only treatment that showed AChE inhibition after 72 h was single CPF exposure, while no significant changes were observed in CES activity. However, after 7-day exposure in artificial soil or 72-h exposure on filter paper, the mixture of NPs+CPF induced a similar degree of AChE and CES inhibition as single CPF exposure. All these suggested that NPs did not produce neurotoxic effects, and that the inhibition of the enzymes’ activities in all cases was due to the presence of the pesticide. On the other hand, the differences in the pattern of Fe accumulation in the earthworms indicate that the presence of other contaminants in the exposure media can modify the uptake and/or the excretion of Fe and evidence the interactions that may be found in binary mixtures of metal oxide NPs and other pre-existing contaminants in the soil ecosystem.Fil: Cáceres Wenzel, Marcela Inés. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fuchs, Julio Silvio. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Bernassani, Florencia Noemí. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; ArgentinaFil: Cochón, Adriana C.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentin

Non-destructive depth reconstruction of Al-Al2_2Cu layer structure with nanometer resolution using extreme ultraviolet coherence tomography

Non-destructive cross-sectional characterization of materials systems with a resolution in the nanometer range and the ability to allow for time-resolved in-situ studies is of great importance in material science. Here, we present such a measurements method, extreme ultraviolet coherence tomography (XCT). The method is non-destructive during sample preparation as well as during the measurement, which is distinguished by a negligible thermal load as compared to electron microscopy methods. Laser-generated radiation in the extreme ultraviolet (XUV) and soft x-ray range is used for characterization. The measurement principle is interferometric and the signal evaluation is performed via an iterative Fourier analysis. The method is demonstrated on the metallic material system Al-Al$_2$Cu and compared to electron and atomic force microscopy measurements. We also present advanced reconstruction methods for XCT which even allow for the determination of the roughness of outer and inner interfaces.Comment: First two authors contributed equally to this work and are ordered alphabetically. 14 page

A high resolution extreme ultraviolet spectrometer system optimized for harmonic spectroscopy and XUV beam analysis

We present a modular extreme ultraviolet (XUV) spectrometer system optimized for a broad spectral range of 12-41 nm (30-99 eV) with a high spectral resolution of λ/Δλ 784 ± 89. The spectrometer system has several operation modes for (1) XUV beam inspection, (2) angular spectral analysis, and (3) imaging spectroscopy. These options allow for a versatile use in high harmonic spectroscopy and XUV beam analysis. The high performance of the spectrometer is demonstrated using a novel cross-sectional imaging method called XUV coherence tomography. © 2019 Author(s)

Absolute EUV reflectivity measurements using a broadband high-harmonic source and an in situ single exposure reference scheme

We present a tabletop setup for extreme ultraviolet (EUV) reflection spectroscopy in the spectral range from 40 to 100 eV by using high-harmonic radiation. The simultaneous measurements of reference and sample spectra with high energy resolution provide precise and robust absolute reflectivity measurements, even when operating with spectrally fluctuating EUV sources. The stability and sensitivity of EUV reflectivity measurements are crucial factors for many applications in attosecond science, EUV spectroscopy, and nano-scale tomography. We show that the accuracy and stability of our in situ referencing scheme are almost one order of magnitude better in comparison to subsequent reference measurements. We demonstrate the performance of the setup by reflective near-edge x-ray absorption fine structure measurements of the aluminum L2/3 absorption edge in α-Al2O3 and compare the results to synchrotron measurements

Goethite nanoparticles in Eisenia andrei: uptake, subcellular effects and their influence on the accumulation of Cd and Pb

El objetivo de este trabajo consistió en investigar la incorporación de nanopartículas (NPs) de goetita (αFeOOH) en la lombriz terrestre Eisenia andrei a través de diferentes vías de exposición. En primer lugar, los organismos fueron expuestos a un suelo artificial adicionado con diferentes suspensiones de NPs para evaluar la absorción a través del tracto gastrointestinal. Después de 10 días, los animales fueron depurados y el contenido de Fe se analizó por espectroscopía de absorción atómica (AAS). Sorprendentemente, los animales expuestos a las NPs presentaron niveles de Fe menores que los controles. Además, no se observó una correlación entre los niveles de NPs en las suspensiones y los valores de concentración de Fe en las lombrices. El ingreso por vía dérmica también fue investigado exponiendo a las lombrices en contacto con papeles de filtro que contenían una suspensión de NPs (50 μg cm-2) durante diferentes tiempos de exposición aguda (24, 48, y 72 h). En los dos primeros períodos de exposición (24 y 48 h) los niveles de Fe aumentaron con respecto a los que se encontraron en los organismos controles. Sin embargo, después de un período de exposición de 72 h, los niveles en las lombrices expuestas fueron menores que en los controles. De manera de explicar este inesperado comportamiento, se evaluó la capacidad antioxidante total en los tejidos de organismos expuestos a papeles de filtro por 72 h, usando el ensayo de TOSC. Se encontró un descenso significativo en la capacidad antioxidante total en los organismos expuestos. Finalmente, se investigó la influencia de las NPs de goetita en el ingreso de Cd y Pb. En este caso, los bioensayos se realizaron exponiendo a las lombrices a papeles de filtro que contenían una solución de cada metal en presencia o ausencia de una suspensión de NPs (50 μg cm-2) por 72 h. Los valores de concentración de Cd y Pb seanalizaron por AAS. Tanto para Cd como para Pb se encontraron descensos significativos en la acumulación de ambos metales (aproximadamente 38%) en las lombrices expuestas a cada metal en presencia de la suspensión de NPs de goetita. En conclusión, la liberación de NPs en ecosistemas terrestres puede inducir algunas respuestas inesperadas en las lombrices y también las NPs pueden interactuar con otros contaminantes preexistentes en el ambiente, modificando su biodisponibilidad.The aim of this work was to investigate whether the terrestrial worm Eisenia andrei incorporates goethite (αFeOOH) nanoparticles (NPs) via different exposure routes. Firstly, organisms were exposed to an artificial soil spiked with different NP suspensions to evaluate the absorption via the gastrointestinal tract. After 10 days, animals were depurated and their Fe content was analyzed by atomic absorption spectrometry (AAS). Surprisingly, animals exposed to NPs presented lower Fe levels than controls. In addition, a correlation between NP suspension levels and Fe concentrations in the worms was not observed. The dermal uptake route was also investigated by exposing the worms in contact to filter papers containing a NP suspension (50 µg cm-2) for different acute exposure times (24, 48, and 72 h). During the first two periods (24 and 48 h) Fe levels increased in relation to those found in control organisms. However, after a 72 h exposure period, levels in exposed worms were lower than in controls. In order to explain this unexpected behavior, the total antioxidant capacity of the whole tissue was evaluated using the TOSC assay in animals exposed to filter papers for 72 h. A significant decrease in the total antioxidant capacity was observed in exposed worms. Finally, the influence of the goethite NPs on the uptake of Cd and Pb was also investigated. In this case, bioassays were performed by exposing worms to filter papers containing a solution of each metal in the presence or in the absence of a NP suspension (50 µg cm-2) for 72 h. Values of Cd and Pb concentrations were analyzed by AAS. For both Cd and Pb, significant decreases (about 38%) in the metal accumulation were found in worms exposed to the metal plus the goethite NP suspension. In conclusion, the release of NPs to terrestrial ecosystems may elicit some unexpected responses in worms and they may also interact with other contaminants already present in the environment, modifying their bioavailability.Fil: Cáceres Wenzel, Marcela Inés. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica. Laboratorio de Toxicología y Química Legal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gigena, Julián. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica. Laboratorio de Toxicología y Química Legal; ArgentinaFil: Fuchs, Julio Silvio. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica. Laboratorio de Toxicología y Química Legal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Oneto, María L.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica. Laboratorio de Toxicología y Química Legal; ArgentinaFil: Cochón, Adriana C.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica. Laboratorio de Toxicología y Química Legal; ArgentinaFil: Casabe, Norma Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Verrengia Guerrero, Noemí R.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica. Laboratorio de Toxicología y Química Legal; Argentin

A Mitochondrial Polymorphism Alters Immune Cell Metabolism and Protects Mice from Skin Inflammation

Several genetic variants in the mitochondrial genome (mtDNA), including ancient polymorphisms, are associated with chronic inflammatory conditions, but investigating the functional consequences of such mtDNA polymorphisms in humans is challenging due to the influence of many other polymorphisms in both mtDNA and the nuclear genome (nDNA). Here, using the conplastic mouse strain B6-mtFVB, we show that in mice, a maternally inherited natural mutation (m.7778G > T) in the mitochondrially encoded gene ATP synthase 8 (mt-Atp8) of complex V impacts on the cellular metabolic profile and effector functions of CD4+ T cells and induces mild changes in oxidative phosphorylation (OXPHOS) complex activities. These changes culminated in significantly lower disease susceptibility in two models of inflammatory skin disease. Our findings provide experimental evidence that a natural variation in mtDNA influences chronic inflammatory conditions through alterations in cellular metabolism and the systemic metabolic profile without causing major dysfunction in the OXPHOS system

In Vitro Identification of Novel Plasminogen-Binding Receptors of the Pathogen Leptospira interrogans

Background: Leptospirosis is a multisystem disease caused by pathogenic strains of the genus Leptospira. We have reported that Leptospira are able to bind plasminogen (PLG), to generate active plasmin in the presence of activator, and to degrade purified extracellular matrix fibronectin. Methodology/Principal Findings: We have now cloned, expressed and purified 14 leptospiral recombinant proteins. The proteins were confirmed to be surface exposed by immunofluorescence microscopy and were evaluated for their ability to bind plasminogen (PLG). We identified eight as PLG-binding proteins, including the major outer membrane protein LipL32, the previously published rLIC12730, rLIC10494, Lp29, Lp49, LipL40 and MPL36, and one novel leptospiral protein, rLIC12238. Bound PLG could be converted to plasmin by the addition of urokinase-type PLG activator (uPA), showing specific proteolytic activity, as assessed by its reaction with the chromogenic plasmin substrate, D-Val-Leu-Lys 4-nitroanilide dihydrochloride. The addition of the lysine analog 6-aminocaproic acid (ACA) inhibited the protein-PLG interaction, thus strongly suggesting the involvement of lysine residues in plasminogen binding. The binding of leptospiral surface proteins to PLG was specific, dose-dependent and saturable. PLG and collagen type IV competed with LipL32 protein for the same binding site, whereas separate binding sites were observed for plasma fibronectin. Conclusions/Significance: PLG-binding/activation through the proteins/receptors on the surface of Leptospira could help the bacteria to specifically overcome tissue barriers, facilitating its spread throughout the host.FAPESP (Fundacao de Amparo a Pesquisa do Estado de Sao Paulo)CNPq (Conselho Nacional de Desenvolvimento Cientifico e Tecnologico)Fundacao Butantan, BrazilFAPESP (Brazil