PIXE MAPS OF INTRACELLULAR ELEMENT DISTRIBUTION IN CEREBELLAR NEURONS

Neurodegenerative disorders are accompanied by altered compositions of metals that may convey some information about the health and possibly metabolic state of neurons. Here we opted for PIXE technique to perform a spatially-resolved elemental analysis of intracellular space of individual neurons. Primarily, we measured element distribution within Purkinje cells (PC) of normal and Lurcher (Lc/+) mutant mice to detect any anomalies in concentrations of individual elements attributable to cell death. Lc/+ mutant mice provide an excellent animal model for time-course of excitotoxic cell death. PCs, some with autofluorescence, were scanned with a proton beam to record their X-ray emission and RBS spectra and to construct 2D-concentration maps of individual elements. PCs with auto-fluorescence, presumed to be either already dead or moribund, showed elevated concentrations of Cu , Fe , and Zn , when compared to healthy PCs. In conclusion, excitotoxic mode of death, as observed in the moribund PCs of Lc/+ cerebellum, may activate enzymatic processes, manifested as increased intracellular concentrations of Cu and Zn that are possibly constituents of some metalloenzyme complexes.

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Fast, High-Resolution X-ray Microfluorescence Imaging

Advances in X-ray Analysis ◽

10.1154/s0376030800014506 ◽

1990 ◽

Vol 34 ◽

pp. 217-221 ◽

Cited By ~ 2

Author(s):

D. A. Carpenter ◽

M. A. Taylor

Keyword(s):

High Resolution ◽

Nondestructive Evaluation ◽

Materials Science ◽

Solid Angle ◽

High Sensitivity ◽

Element Distribution ◽

Beam Power ◽

X Rays ◽

X Ray ◽

Spatially Resolved

X-ray micro fluorescence imaging refers to the use of an x-ray beam as a probe to excite XRF in a specimen and produce a spatially resolved image of the element distribution. The advantages of high sensitivity and low background, together with the nondestructive nature of the measurement, have lead to applications of x-ray microfluorescence analysis in biology, geology, materials science, as well as in the area of nondestructive evaluation. Previous reports have described the development of an x-ray microprobe which uses a conventional source of x-rays to produce a 10-μm beam. This paper describes improvements to the microprobe which have increased the beam power and the solid angle of detection. The data collection and display software have also been enhanced.

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Layered and ion implantation specimens as possible reference materials for the electron-probe microanalysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100132893 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1652-1653

Author(s):

G. Remond ◽

R.H. Packwood ◽

C. Gilles ◽

S. Chryssoulis

Keyword(s):

Ion Implantation ◽

Reference Materials ◽

Analytical Techniques ◽

Thin Film Deposition ◽

Film Deposition ◽

X Ray ◽

Spatially Resolved ◽

Analytical Expressions ◽

Original Approach ◽

Depth Concentration

Merits and limitations of layered and ion implanted specimens as possible reference materials to calibrate spatially resolved analytical techniques are discussed and illustrated for the case of gold analysis in minerals by means of x-ray spectrometry with the EPMA. To overcome the random heterogeneities of minerals, thin film deposition and ion implantation may offer an original approach to the manufacture of controlled concentration/ distribution reference materials for quantification of trace elements with the same matrix as the unknown.In order to evaluate the accuracy of data obtained by EPMA we have compared measured and calculated x-ray intensities for homogeneous and heterogeneous specimens. Au Lα and Au Mα x-ray intensities were recorded at various electron beam energies, and hence at various sampling depths, for gold coated and gold implanted specimens. X-ray intensity calculations are based on the use of analytical expressions for both the depth ionization Φ (ρz) and the depth concentration C (ρz) distributions respectively.

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Sample Environment for Operando Hard X-ray Tomography—An Enabling Technology for Multimodal Characterization in Heterogeneous Catalysis

Catalysts ◽

10.3390/catal11040459 ◽

2021 ◽

Vol 11 (4) ◽

pp. 459

Author(s):

Johannes Becher ◽

Sebastian Weber ◽

Dario Ferreira Sanchez ◽

Dmitry E. Doronkin ◽

Jan Garrevoet ◽

...

Keyword(s):

Heterogeneous Catalysis ◽

Synchrotron Radiation ◽

Contrast Imaging ◽

Co2 Methanation ◽

Full Field ◽

X Ray ◽

Spatially Resolved ◽

Oxidation Of Methane ◽

Unique Source ◽

Sample Environment

Structure–activity relations in heterogeneous catalysis can be revealed through in situ and operando measurements of catalysts in their active state. While hard X-ray tomography is an ideal method for non-invasive, multimodal 3D structural characterization on the micron to nm scale, performing tomography under controlled gas and temperature conditions is challenging. Here, we present a flexible sample environment for operando hard X-ray tomography at synchrotron radiation sources. The setup features are discussed, with demonstrations of operando powder X-ray diffraction tomography (XRD-CT) and energy-dispersive tomographic X-ray absorption spectroscopy (ED-XAS-CT). Catalysts for CO2 methanation and partial oxidation of methane are shown as case studies. The setup can be adapted for different hard X-ray microscopy, spectroscopy, or scattering synchrotron radiation beamlines, is compatible with absorption, diffraction, fluorescence, and phase-contrast imaging, and can operate with scanning focused beam or full-field acquisition mode. We present an accessible methodology for operando hard X-ray tomography studies, which offer a unique source of 3D spatially resolved characterization data unavailable to contemporary methods.

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Exposure of the cytoplasm to low-dose X-rays modifies ataxia telangiectasia mutated-mediated DNA damage responses

Scientific Reports ◽

10.1038/s41598-021-92213-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Munetoshi Maeda ◽

Masanori Tomita ◽

Mika Maeda ◽

Hideki Matsumoto ◽

Noriko Usami ◽

...

Keyword(s):

Dna Damage ◽

Cell Death ◽

Ataxia Telangiectasia ◽

Kinase Inhibitor ◽

Surrogate Marker ◽

X Rays ◽

Ataxia Telangiectasia Mutated ◽

Whole Cell ◽

X Ray ◽

Dna Damage Responses

AbstractWe recently showed that when a low X-ray dose is used, cell death is enhanced in nucleus-irradiated compared with whole-cell-irradiated cells; however, the role of the cytoplasm remains unclear. Here, we show changes in the DNA damage responses with or without X-ray microbeam irradiation of the cytoplasm. Phosphorylated histone H2AX foci, a surrogate marker for DNA double-strand breaks, in V79 and WI-38 cells are not observed in nucleus irradiations at ≤ 2 Gy, whereas they are observed in whole-cell irradiations. Addition of an ataxia telangiectasia mutated (ATM) kinase inhibitor to whole-cell irradiations suppresses foci formation at ≤ 2 Gy. ABL1 and p73 expression is upregulated following nucleus irradiation, suggesting the induction of p73-dependent cell death. Furthermore, CDKN1A (p21) is upregulated following whole-cell irradiation, indicating the induction of cell cycle arrest. These data reveal that cytoplasmic radioresponses modify ATM-mediated DNA damage responses and determine the fate of cells irradiated at low doses.

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More than XRF Mapping: STEAM (Statistically Tailored Elemental Angle Mapper) a Pioneering Analysis Protocol for Pigment Studies

Applied Sciences ◽

10.3390/app11041446 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1446

Author(s):

Jacopo Orsilli ◽

Anna Galli ◽

Letizia Bonizzoni ◽

Michele Caccia

Keyword(s):

Cultural Heritage ◽

Element Distribution ◽

Elemental Distribution ◽

X Rays ◽

Spectral Angle Mapper ◽

X Ray ◽

Fluorescence Radiation ◽

Set Up ◽

Non Destructive ◽

Analysis Protocol

Among the possible variants of X-Ray Fluorescence (XRF), applications exploiting scanning Macro-XRF (MA-XRF) are lately widespread as they allow the visualization of the element distribution maintaining a non-destructive approach. The surface is scanned with a focused or collimated X-ray beam of millimeters or less: analyzing the emitted fluorescence radiation, also elements present below the surface contribute to the elemental distribution image obtained, due to the penetrative nature of X-rays. The importance of this method in the investigation of historical paintings is so obvious—as the elemental distribution obtained can reveal hidden sub-surface layers, including changes made by the artist, or restorations, without any damage to the object—that recently specific international conferences have been held. The present paper summarizes the advantages and limitations of using MA-XRF considering it as an imaging technique, in synergy with other hyperspectral methods, or combining it with spot investigations. The most recent applications in the cultural Heritage field are taken into account, demonstrating how obtained 2D-XRF maps can be of great help in the diagnostic applied on Cultural Heritage materials. Moreover, a pioneering analysis protocol based on the Spectral Angle Mapper (SAM) algorithm is presented, unifying the MA-XRF standard approach with punctual XRF, exploiting information from the mapped area as a database to extend the comprehension to data outside the scanned region, and working independently from the acquisition set-up. Experimental application on some reference pigment layers and a painting by Giotto are presented as validation of the proposed method.

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Discovery of fungal surface NADases predominantly present in pathogenic species

Nature Communications ◽

10.1038/s41467-021-21307-z ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Øyvind Strømland ◽

Juha P. Kallio ◽

Annica Pschibul ◽

Renate H. Skoge ◽

Hulda M. Harðardóttir ◽

...

Keyword(s):

Cell Death ◽

Aspergillus Fumigatus ◽

Neurospora Crassa ◽

Binding Site ◽

Host Cell ◽

Nicotinamide Adenine Dinucleotide ◽

Catalytic Mechanism ◽

Pathogenic Species ◽

X Ray ◽

Cellular Bioenergetics

AbstractNicotinamide adenine dinucleotide (NAD) is a key molecule in cellular bioenergetics and signalling. Various bacterial pathogens release NADase enzymes into the host cell that deplete the host’s NAD+ pool, thereby causing rapid cell death. Here, we report the identification of NADases on the surface of fungi such as the pathogen Aspergillus fumigatus and the saprophyte Neurospora crassa. The enzymes harbour a tuberculosis necrotizing toxin (TNT) domain and are predominately present in pathogenic species. The 1.6 Å X-ray structure of the homodimeric A. fumigatus protein reveals unique properties including N-linked glycosylation and a Ca2+-binding site whose occupancy regulates activity. The structure in complex with a substrate analogue suggests a catalytic mechanism that is distinct from those of known NADases, ADP-ribosyl cyclases and transferases. We propose that fungal NADases may convey advantages during interaction with the host or competing microorganisms.

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Varied actions of proinflammatory cytokines on excitotoxic cell death in the rat central nervous system

Journal of Neuroscience Research ◽

10.1002/jnr.10142 ◽

2002 ◽

Vol 67 (4) ◽

pp. 428-434 ◽

Cited By ~ 13

Author(s):

Stuart M. Allan

Keyword(s):

Central Nervous System ◽

Cell Death ◽

Nervous System ◽

Proinflammatory Cytokines ◽

Excitotoxic Cell Death

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Spatially Resolved Forming Mechanisms Detection in Single Point Incremental Forming Using Synchrotron Based Texture Analysis

Metallurgical and Materials Transactions A ◽

10.1007/s11661-021-06261-1 ◽

2021 ◽

Author(s):

Mateus Dobecki ◽

Alexander Poeche ◽

Walter Reimers

Keyword(s):

Texture Analysis ◽

Incremental Forming ◽

Single Point ◽

High Energy ◽

X Ray Diffraction ◽

X Ray ◽

Forming Mechanism ◽

Spatially Resolved ◽

Step Down ◽

Stress States

AbstractDespite the ongoing success of understanding the deformation states in sheets manufactured by single-point incremental forming (SPIF), the unawareness of the spatially resolved influence of the forming mechanisms on the residual stress states of incrementally formed sheet metal parts impedes their application-optimized use. In this study, a well-founded experimental proof of the occurring forming mechanisms shear, bending and stretching is presented using spatially resolved, high-energy synchrotron x-ray diffraction-based texture analysis in transmission mode. The measuring method allows even near-surface areas to be examined without any impairment of microstructural influences due to tribological reactions. The depth-resolved texture evolution for different sets of forming parameters offers insights into the forming mechanisms acting in SPIF. Therefore, the forming mechanisms are triggered explicitly by adjusting the vertical step-down increment Δz for groove, plate and truncated cone geometries. The texture analysis reveals that the process parameters and the specimen geometries used lead to characteristic changes in the crystallites’ orientation distribution in the formed parts due to plastic deformation. These forming-induced reorientations of the crystallites could be assigned to the forming mechanisms by means of defined reference states. It was found that for groove, plate and truncated cone geometries, a decreasing magnitude of step-down increments leads to a more pronounced shear deformation, which causes an increasing work hardening especially at the tool contact area of the formed parts. Larger step-down increments, on the other hand, induce a greater bending deformation. The plastic deformation by bending leads to a complex stress field that involves alternating residual tensile stresses on the tool and residual compressive stresses on the tool-averted side incrementally formed sheets. The present study demonstrates the potential of high-energy synchrotron x-ray diffraction for the spatially resolved forming mechanism research in SPIF. Controlling the residual stress states by optimizing the process parameters necessitates knowledge of the fundamental forming mechanism action.

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Phase composition depth profiles using spatially resolved energy dispersive X-ray diffraction

Journal of Applied Crystallography ◽

10.1107/s0021889804024148 ◽

2004 ◽

Vol 37 (6) ◽

pp. 967-976 ◽

Cited By ~ 9

Author(s):

Andrew C. Jupe ◽

Stuart R. Stock ◽

Peter L. Lee ◽

Nikhila N. Naik ◽

Kimberly E. Kurtis ◽

...

Keyword(s):

Phase Composition ◽

Spatial Resolution ◽

Zinc Coating ◽

High Energy ◽

Sulfate Attack ◽

Energy Dispersive ◽

X Ray Diffraction ◽

X Ray ◽

Spatially Resolved ◽

Composition Profiles

Spatially resolved energy dispersive X-ray diffraction, using high-energy synchrotron radiation (∼35–80 keV), was used nondestructively to obtain phase composition profiles along the radii of cylindrical cement paste samples to characterize the progress of the chemical changes associated with sulfate attack on the cement. Phase distributions were acquired to depths of ∼4 mm below the specimen surface with sufficient spatial resolution to discern features less than 200 µm thick. The experimental and data analysis methods employed to obtain quantitative composition profiles are described. The spatial resolution that could be achieved is illustrated using data obtained from copper cylinders with a thin zinc coating. The measurements demonstrate that this approach is useful for nondestructively visualizing the sometimes complex transformations that take place during sulfate attack on cement-based materials. These transformations can be spatially related to microstructure as seen by computed microtomography.

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