CL��SS: The hard X-ray absorption beamline of the ALBA CELLS synchrotron

Simonelli, Laura; Marini, Carlo; Olszewski, W.; Pérez, Marta Ávila; Ramanan, Nitya; Guilera, Gemma; Cuartero, Vera; Klementiev, Konstantin

doi:10.1080/23311940.2016.1231987

Cited by 139 publications

(100 citation statements)

References 21 publications

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“…Re LIII edge (Fig. 3b) were conducted in a designated in-situ cell at the CLAESS beamline at ALBA synchrotron 34 (see experimental section for details) under reducing conditions (1 atm, 5% H 2 and 95% He). Continuous changes in the Pt XANES spectra were detected as the reduction temperature was increased until it reached 220 °C, after which no additional changes were obtained in the Pt XANES spectrum (Fig.…”

Section: Resultsmentioning

confidence: 99%

Bimetallic Pt–Re Nanoporous Networks: Synthesis, Characterization, and Catalytic Reactivity

Nijem¹,

Dery²,

Carmiel³

et al. 2018

J. Phys. Chem. C

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The preparation of bimetallic nanoporous networks (BNNs) that combine the high surface area and thermal stability of inorganic nanostructures with the unique catalytic properties of bimetallic systems is highly desirable. Here we show a simple and highly versatile approach for synthesis of Pt-Re BNN and demonstrate the influence of preparation conditions on the BNN structure, composition and catalytic reactivity. Pt-Re BNN was prepared by reduction of double complex [Pt(NH 3 ) 4 ][Re(Cl 6 )] salt crystals, in which two oppositely-charged metal complexes are evenly distributed in each unit cell in a 1:1 ratio. Exposure of the salt crystals to reducing conditions induced the evaporation of the inorganic ligands, collapse of the salt structure and reduction of the metal ions for the formation of high surface area Pt-Re BNNs. Single-particle X-ray fluorescence tomography and various ensemble-based spectroscopy measurements (XPS and XANES) identified that the bulk and surface composition of the bimetallic structure and the oxidation state of the two metals can be tuned by adjusting the reduction temperature of the bimetallic salt. Pt-Re BNN showed reactivity in deoxydehydration reaction of glycerol toward the selective formation of allyl alcohol. Combination of reactivity and spectroscopic measurements revealed that enhanced reactivity was correlated to the presence of highly oxidized Re species (mostly Re +7 ) and equal distribution of Pt and Re on the BNN surface.

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Section: Resultsmentioning

confidence: 99%

Bimetallic Pt–Re Nanoporous Networks: Synthesis, Characterization, and Catalytic Reactivity

Nijem¹,

Dery²,

Carmiel³

et al. 2018

J. Phys. Chem. C

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“…70 However, SuperXAS at the SLS, 57 along with virtually all spectroscopy lines capable of the sorts of experiments we have conducted in this study, (e.g. B18 (Diamond Light Source 71 ), Rock and Samba (Soleil 72,73 ), Balder (Max IV 74 ), CLAESS (Alba 75 ) and P64/P65 (Hamburg 76,77 ) either utilize focusing elements, or are situated on insertion devices capable of delivering higher photon fluxes and densities than either SuperXAS, or BM31. We note, however, that in the case of P65, 77 although situated on an undulator, this line is designed to yield relatively large beam spots (1 Â 0.5 mm) and uses no focusing elements.…”

Section: Methodsmentioning

confidence: 99%

Unwanted effects of X-rays in surface grafted copper(ii) organometallics and copper exchanged zeolites, how they manifest, and what can be done about them

Newton

Knorpp

Meyet

et al. 2020

Phys. Chem. Chem. Phys.

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“…Fe K-edge measurements were performed in transmission mode, as well as the M K-edge measurements of commercial reference samples ( Due to the low M-metal concentration of the samples, the M K-edge measurements of the bacterial and isolated magnetosome samples were performed in fluorescence yield mode using a silicon-drift diode (SDD) solid-state detector (ALBA) or an energy-dispersive 13-element Si(Li) multidetector (ESRF). Under these conditions, the detection limit of the technique is as low as 10 ppm (10 mg/kg) 39 . From three to five spectra were acquired for each sample and merged to improve the signal-to-noise ratio.…”

Section: X-ray Absorption Near Edge Spectroscopy (Xanes)mentioning

confidence: 97%

Magnetosomes could be protective shields against metal stress in magnetotactic bacteria

ntildeoz

Marcano

iacuteguez

et al. 2020

Preprint

Self Cite

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Magnetotactic bacteria are aquatic microorganisms with the ability to biomineralise membrane-enclosed magnetic nanoparticles, called magnetosomes. These magnetosomes are arranged into a chain that behaves as a magnetic compass, allowing the bacteria to align in and navigate along the Earth's magnetic field lines. According to the magneto-aerotactic hypothesis, the purpose of producing magnetosomes is to provide the bacteria with a more efficient movement within the stratified water column, in search of the optimal positions that satisfy their nutritional requirements. However, magnetosomes could have other physiological roles, as proposed in this work. Here we analyse the role of magnetosomes in the tolerance of Magnetospirillum gryphiswaldense MSR-1 to transition metals (Co, Mn, Ni, Zn, Cu). By exposing bacterial populations with and without magnetosomes to increasing concentrations of metals in the growth medium, we observe that the tolerance is significantly higher when bacteria have magnetosomes. The resistance mechanisms triggered in magnetosome-bearing bacteria under metal stress have been investigated by means of x-ray absorption near edge spectroscopy (XANES). XANES experiments were performed both on magnetosomes isolated from the bacteria and on the whole bacteria, aimed to assess whether bacteria use magnetosomes as metal storages, or whether they incorporate the excess metal in other cell compartments. Our findings reveal that the tolerance mechanisms are metal-specific: Mn, Zn and Cu are incorporated in both the magnetosomes and other cell compartments; Co is only incorporated in the magnetosomes, and Ni is incorporated in other cell compartments. In the case of Co, Zn and Mn, the metal is integrated in the magnetosome magnetite mineral core.Magnetotactic bacteria (MTB) are aquatic microorganisms able to passively align parallel to the Earth's geomagnetic field lines while they actively swim. This behavior, known as magnetotaxis, is due to the presence of unique intracellular magnetic organelles called magnetosomes 1-4 . The magnetosomes are intracellular inclusions composed by a core of magnetic iron mineral, typically magnetite (Fe 3 O 4 ) or greigite (Fe 3 S 4 ), enclosed by a thin membrane.Magnetotactic bacteria are widespread in freshwater and marine environments 5 . They are easily detected in chemically and redox stratified sediments and water columns, predominantly at the oxic-anoxic transition zones (OATZ). Bacteria living in OATZ, with vertical chemical gradients, are continually searching the optimal position in the stratified water column in order to satisfy their nutritional requirements. Under these circumstances, magnetotaxis is thought to be a great advantage by increasing the efficiency of chemotaxis 1 . Due to their inclination, the geomagnetic field lines act as vertical pathways in a stratified environment, therefore the bacteria aligned in the Earth's field reduce a three dimensional search to a single dimension, swimming up-downwards the stratified column.Another possible role of...

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CL��SS: The hard X-ray absorption beamline of the ALBA CELLS synchrotron

Cited by 139 publications

References 21 publications

Bimetallic Pt–Re Nanoporous Networks: Synthesis, Characterization, and Catalytic Reactivity

Bimetallic Pt–Re Nanoporous Networks: Synthesis, Characterization, and Catalytic Reactivity

Unwanted effects of X-rays in surface grafted copper(ii) organometallics and copper exchanged zeolites, how they manifest, and what can be done about them

Magnetosomes could be protective shields against metal stress in magnetotactic bacteria

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