Mateusz Czyzycki

LabVIEW control software for scanning micro-beam X-ray fluorescence spectrometer

Confocal micro-beam X-ray fluorescence microscope was constructed. The system was assembled from commercially available components - a low power X-ray tube source, polycapillary X-ray optics and silicon drift detector - controlled by an in-house developed LabVIEW software. A video camera coupled to optical microscope was utilized to display the area excited by X-ray beam. The camera image calibration and scan area definition software were also based entirely on LabVIEW code. Presently, the main area of application of the newly constructed spectrometer is 2-dimensional mapping of element distribution in environmental, biological and geological samples with micrometer spatial resolution. The hardware and the developed software can already handle volumetric 3-D confocal scans. In this work, a front panel graphical user interface as well as communication protocols between hardware components were described. Two applications of the spectrometer, to homogeneity testing of titanium layers and to imaging of various types of grains in air particulate matter collected on membrane filters, were presented.

Neuroprotective action of FK-506 (tacrolimus) after seizures induced with pilocarpine: quantitative and topographic elemental analysis of brain tissue

In the present work, X-ray fluorescence microscopy with a synchrotron source for the exciting radiation was applied for topographic and quantitative elemental analysis of rat brain tissue in pilocarpine-induced epilepsy and neuroprotection with FK-506. The mass per unit area of the elements P, S, Cl, K, Ca, Fe, Cu, Zn, Se, Br, and Rb was determined in four fields of the hippocampal formation (sectors 1 and 3 of Ammon’s horn–CA1, CA3; dentate gyrus; hilus of dentate gyrus) and the parietal cortex. The results obtained for epileptic rats treated with FK-506 (SNF) were compared with data obtained previously for epileptic rats (SNS) and a control group. Many statistically significant differences in elemental composition were observed between the SNF and SNS groups. Higher mass per unit area of P was noticed in CA1 and CA3 regions of the hippocampus of SNF rats in comparison with SNS rats. A similar relation was observed for K in all five brain areas analyzed. Also, Fe in CA3 and dentate gyrus, Cu in the parietal cortex, and Zn in CA3 and in the cortex were present at a higher level in the SNF group in comparison with the SNS group. The findings obtained in the present study suggest that the neuroprotective action of FK-506 in epileptic rat brain may involve not only the inhibition of calcineurin but also blockade of the K+ channels.

Direct deconvolution approach for depth profiling of element concentrations in multi-layered materials by confocal micro-beam X-ray fluorescence spectrometry.

A new approach for the determination of element concentration profiles in stratified materials by confocal X-ray fluorescence spectrometry was elaborated. The method was based on a direct deconvolution of the measured depth-dependent X-ray fluorescence intensity signal with the established response function of the spectrometer. Since the approach neglects the absorption of primary and secondary radiation within the probing volume, it is applicable only to low absorbing samples and small probing volumes. In the proposed approach the deconvolution is performed separately for all detectable elements and it is followed by the correction of absorption effects. The proposed approach was validated by using stratified standard samples. The determined elemental profiles were compared with the results obtained by using existing analytical approaches.

Depth profiling of element concentrations in stratified materials by confocal microbeam X-ray fluorescence spectrometry with polychromatic excitation.

The confocal microbeam X-ray fluorescence technique is a well-established analytical tool that is widely used for qualitative and quantitative analysis of stratified materials. There are several different reconstruction methods dedicated to this type of samples. However, these methods are applicable with monochromatic excitation only. The full description of matrix effects and geometrical effects for polychromatic X-ray photons in confocal geometry is a demanding task. In the present paper, this problem was overcome by the use of effective energy approximation. The reduction of the whole energy dimension into one effective value eliminates the necessity of integration over the primary beam energy range for a number of basic parameters. This simplification is attainable without loss of the accuracy of analysis. The proposed approach was validated by applying it to the reconstruction of element concentration depth profiles of stratified standard samples measured with tabletop confocal microbeam X-ray fluorescence setup and by comparing the obtained results of two independent algorithms.

An integrated experimental and analytical approach to the chemical state imaging of iron in brain gliomas using X-ray absorption near edge structure spectroscopy.

X-ray absorption near-edge structure spectroscopy is used for human neoplastic tissues in order to investigate distributions and chemical states of iron. The specimens used in this study were obtained intraoperatively from brain gliomas of different types and various grades of malignancy and from a control subject. An integrated experimental and analytical approach toward topographic and quantitative analysis in thin freeze-dried cryo-sections is presented. The full XANES spectra at the Fe absorption K edge show the presence of both chemical forms of Fe in the analyzed points of the tissues. The main goal of the work is the chemical state imaging of Fe in tissue areas. Topographic analysis of Fe speciation in the tissues investigated with the use of the XANES technique indicates the presence of microstructures where Fe(2+) is dominant as well as those with a high abundance of the oxidized form of Fe. The quantitative analysis shows that for all cases the content of the oxidized form of Fe is significantly higher in comparison with Fe(2+). The highest level of Fe(3+) is found in the control sample, and the lowest one for the glioma of the highest grade of malignancy. The content of either Fe(2+) or Fe(3+) is increased in low grade gliomas in comparison to high-grade malignant tumors.

Quantitative Elemental Microanalysis Of Individual Particles With Use Of X‐Ray Fluorescence Method And Monte Carlo Simulation

Recently a considerable interest has been triggered in the investigation of the composition of individual particles by X‐ray fluorescence microanalysis. The sources of these micro‐samples are mostly diversified. These samples come from space dust, air and ash, soil as well as environment and take the shape of a sphere or an oval. In analysis this kind of samples the geometrical effects caused by different sizes and shapes influence on accuracy of results. This fact arises from the matrix effect. For these samples it is not possible to find analytically a solution of equation taking into account an absorption of X‐rays. Hence, a way out is to approximate the real sample shape with the other one or to use Monte Carlo (MC) simulation method. In current work authors utilized the iterative MC simulation to assess an elemental percentage of individual particles. The set of glass micro‐spheres, made of NIST K3089 material of known chemical composition, with diameters in the range between 25 and 45 μm was investi...