Brazilian Synchrotron Research Articles

Elemental changes in hemolymph and urine of Rhodnius prolixus induced by in-vivo exposure to mercury: A study using synchrotron radiation total reflection X-ray fluorescence

In recent years, the effects of pollution on the health of humans and other vertebrates were extensively studied. However, the effects on some invertebrates are comparatively unknown. Recent studies have demonstrated that toxic metals interfere with the reproduction, development and immune defenses of some terrestrial and marine invertebrates. Some environmental conditions including pollution produce chronic and acute effects on different animal's organs and systems. In this work, we investigated changes in the concentrations of Cl, K, Ca, Fe and Zn in Rhodnius prolixus as insect model. The elements were quantified using urine and hemolymph samples collected on different days after feeding the insects with blood containing HgCl2. The synchrotron radiation total reflection X-ray fluorescence measurements were carried at the X-ray fluorescence beamline facility in Brazilian Synchrotron Light Laboratory. The observation reveals that the calcium level was higher in the hemolymph than in urine. On the other hand, the urine collected from insects treated with HgCl2 showed higher level of Cl than hemolymph samples. Ca, Fe and Zn concentrations decrease drastically in urine samples collected after 2days of HgCl2 treatment. The regulation of triatomines excretion was discussed pointing out the importance of trace elements.

Super hybrid quadrupoles

A new model of quadrupole composed of permanent magnetic material, coils and soft magnetic material is proposed for the new Brazilian Synchrotron Light Source (Sirius). These quadrupoles must have flexibility about 30% of the total gradient in order to correct the linear effects caused by the insertion devices on the beam dynamics. This flexibility is obtained using coils while permanent magnets are used to supply the constant gradient.

Elemental distribution images in prostate samples by X-ray fluorescence microtomography

An X-ray transmission microtomography (CT) system combined with an X-ray fluorescence microtomography (XRFμCT) system was implemented in the Brazilian Synchrotron Light Laboratory (LNLS), in order to determine the elemental distribution in prostate samples aiming at establishing a correlation between the concentration of some elements and the characteristics and pathology of the tissues.The CT images were reconstructed using a filtered-back projection algorithm and the XRFμCT images were reconstructed using a filtered-back projection algorithm with absorption corrections.

Comparative Survival Analysis ofDeinococcus radioduransand the HaloarchaeaNatrialba magadiiandHaloferax volcaniiExposed to Vacuum Ultraviolet Irradiation

The haloarchaea Natrialba magadii and Haloferax volcanii, as well as the radiation-resistant bacterium Deinococcus radiodurans, were exposed to vacuum UV (VUV) radiation at the Brazilian Synchrotron Light Laboratory. Cell monolayers (containing 105 to 106 cells per sample) were prepared over polycarbonate filters and irradiated under high vacuum (10−5 Pa) with polychromatic synchrotron radiation. N. magadii was remarkably resistant to high vacuum with a survival fraction of (3.77±0.76)×10−2, which was larger than that of D. radiodurans (1.13±0.23)×10−2. The survival fraction of the haloarchaea H. volcanii, of (3.60±1.80)×10−4, was much smaller. Radiation resistance profiles were similar between the haloarchaea and D. radiodurans for fluences up to 150 J m−2. For fluences larger than 150 J m−2, there was a significant decrease in the survival of haloarchaea, and in particular H. volcanii did not survive. Survival for D. radiodurans was 1% after exposure to the higher VUV fluence (1350 J m−2), while N. magadii had a survival lower than 0.1%. Such survival fractions are discussed regarding the possibility of interplanetary transfer of viable microorganisms and the possible existence of microbial life in extraterrestrial salty environments such as the planet Mars and Jupiter's moon Europa. This is the first work to report survival of haloarchaea under simulated interplanetary conditions. Key Words: Vacuum ultraviolet—Synchrotron—Radiation resistance—Planetary protection—Panspermia. Astrobiology 11, 1034–1040.

Energy dispersive X-ray reflectivity applied to the study of thermal stability of self-assembled organic multilayers: Results on phosphonic acids

The temperature evolution of self-assembled phosphonic acid multilayers was investigated by energy dispersive X-ray reflectivity and angular-resolved reflectivity. Energy dispersive measurements were performed in an experimental setup specially designed for the X-ray fluorescence beamline of the Brazilian Synchrotron Light Laboratory. It allows the precise monitoring of phase transitions observed in organic thin film and multilayer systems. The studied multilayers – obtained from dip coating of a solution of octadecylphosphonic acid – present different bilayer periodicities of 50Å (straight bilayer) and 34Å (tilted bilayer). Energy dispersive and angular-resolved data evidence re-organization of the lamellar ordering of octadecylphosphonic acid multilayers as a function of temperature. The energy dispersive technique presents many advantages over conventional methods such as short acquisition time, possibility to vary external parameters and high flux, making it suitable for light scatterers as polymers and other organic molecules.

Investigation of mineral distribution in bone by synchrotron X-ray fluorescence microscopy after tibolone therapy

Abstract Tibolone is a synthetic steroid with estrogenic, androgenic, and progestagenic properties used for the prevention of postmenopausal osteoporosis and treatment of climacteric symptoms. Tibolone shows almost no action on breast and endometrium, which are target-organs for estrogens and progesterone activity. The aim of this work was to investigate the spatial distribution of calcium and zinc minerals in the femoral head of ovariectomized rat in order to evaluate the effects of the long-term administration of tibolone. For that purpose X-ray microfluorescence was used with synchrotron radiation imaging technique which was performed at Brazilian Light Synchrotron Laboratory, Campinas, SP. Minerals were not homogeneously distributed in trabecular bone areas; a higher concentration of calcium in the trabecular regions at femoral heads was found in ovariectomized and tibolone-treated rats compared to ovariectomized and control groups.

Surface structure determination of Pd on W(100) using X-ray photoelectron diffraction

Ferromagnetic ordering in non-ferromagnetic transition metals induced by structural effects such as lattice expansion and stacking faults have been predicted by several theoretical studies. Different surfaces such as Nb(100), W(100) and C(0001) have been suggested as potential templates which could drive a Pd ultrathin film to a stable ferromagnetic state, depending on growth packing, film thickness and lateral lattice parameter. In this work we present an X-ray photoelectron diffraction (XPD) study of sub-monolayer to a few layers of Pd grown on W(100) and its surface structure determination. XPD patterns of Pd 3d and W 4f peaks were measured using synchrotron radiation with photon energy of 1810eV provided by the SXS beamline at the Brazilian Synchrotron Light Laboratory. Our results indicate that the first few monolayers of Pd grow on W(100) with bcc packing and lateral lattice parameter dramatically changed in comparison with the Pd(fcc) bulk values. Based on these results we also present a discussion on the magnetic properties of this system derived from spin-polarized DFT calculation.

3D elemental distribution images in biological samples by XRFµCT

An X-ray transmission microtomography (CT) system combined with an X-ray fluorescence microtomography (XRFµCT) system was implemented in the Brazilian Synchrotron Light Laboratory (LNLS), Campinas, Brazil. The aim of this work was to determine the elemental distribution in biological samples (breast, prostate and lung samples) in order to verify the concentration of some elements correlated with characteristics and pathology of each tissue observed by the transmission CT. The experiments were performed at the X-ray fluorescence beamline (D09B-XRF) of the Brazilian Synchrotron Light Laboratory, Campinas, Brazil. A quasi-monochromatic beam produced by a multilayer monochromator was used as an incident beam. The sample was placed on a high-precision goniometer and translation stages that allow rotating as well as translating it perpendicularly to the beam. The fluorescence photons were collected with an energy dispersive HPGe detector placed at 90° to the incident beam, while transmitted photons were detected with a fast Na(Tl) scintillation counter placed behind the sample on the beam path. The CT images were reconstructed using a filtered-back projection algorithm and the XRFµCT images were reconstructed using a filtered-back projection algorithm with absorption corrections. The 3D images were reconstructed using the 3D-DOCTOR software. Results from the 3D visualization showed that the distribution of iron, copper and zinc is different and heterogeneous from the analyzed samples. Copyright © 2011 John Wiley & Sons, Ltd.

Chemical environment determination of iron oxides using RRS spectroscopy

This article presents first results of determination of the oxidation state of several Fe samples by means of resonant Raman scattering spectroscopy (RRS) using monochromatic synchrotron radiation with an energy-dispersive system. Measurements of samples of Fe, FeO, Fe2O3 and Fe3O4 were carried out at the XRF station of the D09B-XRF beamline at Brazilian synchrotron facility (LNLS, Campinas, Brazil). The samples were irradiated with monochromatic photons having energy close and lower than the K absorption edge of iron in order to inspect the RRS emissions. The RRS spectra were analyzed with specific programs for fitting the experimental data to theoretical expressions. Then, residuals were determined in the low-energy side of the RRS peaks. These residuals were treated with Fast Fourier Transform (FFT) smoothing methods taking into account the instrument functions of the detecting system. The residuals show an oscillation pattern that depends on the studied sample, i.e. on the oxidation state of Fe. The changes existing in the RRS structure between Fe and its oxides are clearly discriminated, suggesting chemical environment characterization by RRS spectroscopy using an energy-dispersive system combined with synchrotron radiation. Copyright © 2011 John Wiley & Sons, Ltd.

Synchrotron radiation X-ray microfluorescence techniques and biological applications

Synchrotron X-ray imaging systems with fluorescence techniques was developed for biomedical researches in Brazilian Synchrotron Laboratory. An X-ray fluorescence microtomography system was implemented to analyse human prostate and breast samples and an X-ray microfluorescence system was implemented to study bone sites of human and animal samples with and without bone disorders.

Photoabsorption and desorption studies on thiophene-based polymers following sulphur K-shell excitation

Photon stimulated ion desorption (PSID) and NEXAFS studies have been performed on thiophene-based polymers at the Brazilian Synchrotron Light Source following sulphur K-shell photoexcitation. For poly(thiophene) (PT) and poly(3-methylthiophene) (P3MT) it was found that the S 1 s → π *, σ * (S–C) excitation produces S + desorption efficiently. On the other hand, S 2+ desorption is enhanced at higher energy excitations. These results are interpreted in terms of the Auger-stimulated ion desorption mechanism. For poly(3-hexylthiophene) (P3HT) S + desorption seems to be suppressed, which may be due to the hexyl side-chains. Desorption ion yield curves for molecular fragments reproduce the photoabsorption spectrum, being dominated by the indirect process.

Photostability of gas- and solid-phase biomolecules within dense molecular clouds due to soft X-rays

An experimental photochemistry study involving gas- and solid-phase amino acids (glycine, DL-valine, DL-proline) and nucleobases (adenine and uracil) under soft X-rays was performed. The aim was to test the molecular stabilities of essential biomolecules against ionizing photon fields inside dense molecular clouds and protostellar disks analogs. In these environments, the main energy sources are the cosmic rays and soft X-rays. The measurements were taken at the Brazilian Synchrotron Light Laboratory (LNLS), employing 150 eV photons. In-situ sample analysis was performed by Time-of-flight mass spectrometer (TOF-MS) and Fourier transform infrared (FTIR) spectrometer, for gas- and solid- phase analysis, respectively. The half-life of solid phase amino acids, assumed to be present at grain mantles, is at least 3E5 years and 3E8 years inside dense molecular clouds and protoplanetary disks, respectively. We estimate that for gas-phase compounds these values increase one order of magnitude since the dissociation cross section of glycine is lower at gas-phase than at solid phase for the same photon energy. The half-life of solid phase nucleobases is about 2-3 orders of magnitude higher than found for amino acids. The results indicate that nucleobases are much more resistant to ionizing radiation than amino acids. We consider these implications for the survival and transfer of biomolecules in space environments.

3D elemental distribution images by XRFμCT at LNLS—Brazil

An X-ray Transmission Microtomography (CT) system combined with an X-ray Fluorescence Microtomography (XRFμCT) system was implemented in the Brazilian Synchrotron Light Laboratory (LNLS), Campinas, Brazil. The main objective of this work is to determine the elemental distribution in biological samples (breast, prostate and lung samples) in order to verify the concentration of some elements correlated with characteristics and pathology of each tissue observed by the transmission CT. The experiments were performed at the X-Ray Fluorescence beamline (D09B-XRF) of the Brazilian Synchrotron Light Laboratory, Campinas, Brazil. A quasi-monochromatic beam produced by a multilayer monochromator was used as an incident beam. The sample was placed on a high precision goniometer and translation stages that allow its rotation as well as translation perpendicular to the beam. The fluorescence photons were collected with an energy dispersive HPGe detector placed at 90° to the incident beam, while transmitted photons were detected with a fast Na(Tl) scintillation counter placed behind the sample on the beam direction. The CT images were reconstructed using a filtered back-projection algorithm and the XRFμCT were reconstructed using a filtered back-projection algorithm with absorption corrections. The 3D images were reconstructed using the 3D-DOCTOR software.

X-ray photodesorption from methanol ice

The abundances of molecules and ions depend on the mechanisms of their formation and destruction that can occur both in the gas phase and in the condensed phase on grain surfaces. Photodesorption of grain surface species may explain the relative high abundances of gaseous neutral or ionic species detected in cold environments. X-ray photons from young stars are able to penetrate cold and dense regions inside protoplanetary discs, leading to molecular dissociation and desorption of photo-products from icy molecules on grain mantles. This paper aims to experimentally investigate the contribution of ion desorption from methanol ice stimulated by soft X-rays for producing chemically active ions in protoplanetary discs. The measurements were carried out at the Brazilian synchrotron light source (LNLS), using X-ray photons at the methanol O1s resonance energy (537 eV). Some possible pathways for the H − and O − formation from singly charged desorbed ions are suggested. The photodesorption yields for positive and negative ions were determined and compared with previous results obtained using different ionization agents, such as electrons, heavy ions and photons at different energies. We also correlate our results to the ion production in protoplanetary discs.

Growth of EuTe islands on SnTe by molecular beam epitaxy

Semiconductor magnetic quantum dots are very promising structures, with novel properties that find multiple applications in spintronic devices. EuTe is a wide gap semiconductor with NaCl structure, and strong magnetic moments S=7/2 at the half filled 4f 7 electronic levels. On the other hand, SnTe is a narrow gap semiconductor with the same crystal structure and 4% lattice mismatch with EuTe. In this work, we investigate the molecular beam epitaxial growth of EuTe on SnTe after the critical thickness for island formation is surpassed, as a previous step to the growth of organized magnetic quantum dots. The topology and strain state of EuTe islands were studied as a function of growth temperature and EuTe nominal layer thickness. Reflection high energy electron diffraction (RHEED) was used in-situ to monitor surface morphology and strain state. RHEED results were complemented and enriched with atomic force microscopy and grazing incidence X-ray diffraction measurements made at the XRD2 beamline of the Brazilian Synchrotron. EuTe islands of increasing height and diameter are obtained when the EuTe nominal thickness increases, with higher aspect ratio for the islands grown at lower temperatures. As the islands grow, a relaxation toward the EuTe bulk lattice parameter was observed. The relaxation process was partially reverted by the growth of the SnTe cap layer, vital to protect the EuTe islands from oxidation. A simple model is outlined to describe the distortions caused by the EuTe islands on the SnTe buffer and cap layers. The SnTe cap layers formed interesting plateau structures with easily controlled wall height, that could find applications as a template for future nanostructures growth.

Laboratory simulation of interplanetary ultraviolet radiation (broad spectrum) and its effects on Deinococcus radiodurans

The radiation-resistant bacterium Deinococcus radiodurans was exposed to a simulated interplanetary UV radiation at the Brazilian Synchrotron Light Laboratory (LNLS). Bacterial samples were irradiated on different substrates to investigate the influence of surface relief on cell survival. The effects of cell multi-layers were also investigated. The ratio of viable microorganisms remained virtually the same (average 2%) for integrated doses from 1.2 to 12 kJ m −2, corresponding to 16 h of irradiation at most. The asymptotic profiles of the curves, clearly connected to a shielding effect provided by multi-layering cells on a cavitary substrate (carbon tape), means that the inactivation rate may not change significantly along extended periods of exposure to radiation. Such high survival rates reinforce the possibility of an interplanetary transfer of viable microbes.

Description and performance of an electron-ion coincidence TOF spectrometer used at the Brazilian synchrotron facility LNLS

This paper reports the characteristics and performance of a Time-of-Flight Mass Spectrometer (TOF-MS) for coincidence measurements between electrons and ions that has been developed jointly in Sweden and Brazil. The spectrometer, used for studies of inner-shell photoexcitation of molecules in the gas-phase, has been optimized by implementing ion and electron lenses to allow the use of relatively small diameter detectors. Simulations were performed to understand the lens performance and they show that ions (electrons) could be collected without angular discrimination with a maximum kinetic energy up to ten (two) times higher than without the lens actions. A rotary vacuum chamber allows the spectrometer axis to be positioned at different angles relative to the polarization vector of the excitation beam. An important characteristic of the apparatus is that the acquisition setup allows a multi-hit capability with 1 ns resolution. Hereby, Photoelectron–Photoion–Photoion Coincidence (PEPIPICO) measurements can be performed on molecules containing two or more atoms of equal mass. A method to obtain experimental detection efficiencies of a single ion and one of one, two or three electrons has been developed. A systematic study of the interaction region has been performed to determine the shape of the photon and gas beams. Measurements on molecular nitrogen demonstrate the spectrometer's ability to resolve fragments with the same charge to mass ratio arriving within only a few ns. Simulations and experimental results of fragmentation of two singly charged cation nitrogen atoms agree, confirming that the spectrometer performance is well understood.

Avaliação de multielementos em amostras de sangue humano usando SR-TXRF

A técnica de fluorescência de raios X por reflexão total usando radiação síncrotron (SR-TXRF) é uma poderosa ferramenta utilizada para a determinação das concentrações elementares presentes em amostras biológicas. O objetivo deste estudo é avaliar as possíveis alterações causadas por processos de irradiação na concentração de elementos-traço em amostras de sangue humano. As amostras de sangue foram coletadas no Laboratório de Análises Clínicas Dr. Elilel Figueiredo, Rio de Janeiro, e divididas em dois grupos. O primeiro grupo foi irradiado com doses de 1.500, 2.500 e 3.000 cGy, utilizando o irradiador Gammacell 220 Excel, e o segundo foi irradiado com doses que variaram de 2 cGy a 100 cGy, utilizando uma bomba de cobalto Theratron 780 C do Inca, Rio de Janeiro. Todas as amostras de sangue total, plasma e matriz celular foram então liofilizadas e, em seguida, passaram pelo procedimento padrão de digestão. Todas as medidas foram realizadas na linha de fluorescência de raios X do Laboratório Nacional de Luz Síncrotron (LNLS), em Campinas, Brasil. Não se verificou variação significativa na concentração de Ca e, em contrapartida, o K foi o único elemento que sofreu alterações significativas para todas as amostras analisadas em função da dose. A concentração de Fe diminuiu apenas para as amostras de sangue total e plasma. A concentração de Zn apresentou uma diminuição significativa somente para as amostras de sangue total.

Biological tissues analysis by XRF microtomography

The main of this work is to determine the elemental distribution in breast and prostate tissue samples in order to verify the concentration of some elements correlated with characteristics and pathology of each tissue observed by the X-ray transmission microtomography (microCT). The experiments were performed at the X-ray fluorescence beamline of the Brazilian Synchrotron Light Laboratory. The microCT images were reconstructed using a filtered-back-projection algorithm and the XRF microtomographies were reconstructed using a filtered-back-projection algorithm with absorption corrections.

Energy-dispersive X-ray absorption spectroscopy at LNLS: investigation on strongly correlated metal oxides

An energy-dispersive X-ray absorption spectroscopy beamline mainly dedicated to X-ray magnetic circular dichroism (XMCD) and material science under extreme conditions has been implemented in a bending-magnet port at the Brazilian Synchrotron Light Laboratory. Here the beamline technical characteristics are described, including the most important aspects of the mechanics, optical elements and detection set-up. The beamline performance is then illustrated through two case studies on strongly correlated transition metal oxides: an XMCD insight into the modifications of the magnetic properties of Cr-doped manganites and the structural deformation in nickel perovskites under high applied pressure.