Browsing by Subject "Scanning electron microscopy"

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  • Voutilainen, Mikko; Miettinen, Arttu; Sardini, Paul; Parkkonen, Joni; Sammaljärvi, Juuso; Gylling, Björn; Selroos, Jan-Olof; Yli-Kaila, Maarit; Koskinen, Lasse; Siitari-Kauppi, Marja (2019)
    The spatial porosity and mineral distribution of geological materials strongly affects transport processes in them. X-ray micro computed tomography (X-mu CT) has proven to be a powerful tool for characterizing the spatial mineral distribution of geological samples in 3-D. However, limitations in resolution prevent an accurate characterization of pore space especially for tight crystalline rock samples and 2-D methods such as C-14-polymethylmethacrylate (C-14-PMMA) autoradiography and scanning electron microscopy (SEM) are needed. The spatial porosity and mineral distributions of tight crystalline rock samples from Aspo, Sweden, and Olkiluoto, Finland, were studied here. The X-mu CT were used to characterize the spatial distribution of the main minerals in 3-D. Total porosities, fracture porosities, fracture densities and porosity distributions of the samples were determined using the C-14-PMMA autoradiography and characterization of mineral-specific porosities were assisted using chemical staining of rock surfaces. SEM and energy dispersive X-ray spectroscopy (EDS) were used to determine pore apertures and identify the minerals. It was shown that combination of the different imaging techniques creates a powerful tool for the structural characterization of crystalline rock samples. The combination of the results from different methods allowed the construction of spatial porosity, mineral and mineral grain distributions of the samples in 3-D. These spatial distributions enable reactive transport modeling using a more realistic representation of the heterogeneous structure of samples. Furthermore, the realism of the spatial distributions were increased by determinig the densities and porosities of fractures and by the virtual construction heterogeneous mineral distributions of minerals that cannot be separated by X-mu CT.
  • Mäkelä, Kati; Ollila, Hely; Sutinen, Eva; Vuorinen, Vesa; Peltola, Emilia; Kaarteenaho, Riitta; Myllärniemi, Marjukka (2019)
    Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease with a dismal prognosis and an unknown etiology. Inorganic dust is a known risk factor, and air pollution seems to affect disease progression. We aimed to investigate inorganic particulate matter in IPF lung tissue samples. Using polarizing light microscopy, we examined coal dust pigment and inorganic particulate matter in 73 lung tissue samples from the FinnishIPF registry. We scored the amount of coal dust pigment and particulate matter from 0 to 5. Using energy dispersive spectrometry with a scanning electron microscope, we conducted an elemental analysis of six IPF lung tissue samples. We compared the results to the registry data, and to the population density and air quality data. To compare categorical data, we used Fisher's exact test; we estimated the survival of the patients with Kaplan-Meier curves. We found inorganic particulate matter in all samples in varying amounts. Samples from the southern regions of Finland, where population density and fine particle levels are high, more often had particulate matter scores from 3 to 5 than samples from the northern regions (31/50, 62.0% vs. 7/23, 30.4%, p = 0.02). The highest particulate matter scores of 4 and 5 (n = 15) associated with a known exposure to inorganic dust (p = 0.004). An association between particulate matter in the lung tissue of IPF patients and exposure to air pollution may exist.
  • Göhre, Felix; Ludtka, Christopher; Hamperl, Melanie; Friedmann, Andrea; Straube, Anja; Mendel, Thomas; Heilmann, Andreas; Meisel, Hans Jorg; Schwan, Stefan (2017)
    Segmental degeneration in the human lumbar spine affects both the intervertebral discs and facet joints. Facet joint degeneration not only affects the cartilage surface, but also alters the cellular properties of the cartilage tissue and the structure of the subchondral bone. The primary focus of this study is the investigation of these microstructural changes that are caused by facet joint degeneration. Microstructural analyses of degenerated facet joint samples, obtained from patients following operative lumbar interbody fusion, have not previously been extensively investigated. This study analyzes human facet joint samples from the inferior articular process using scanning electron microscopy, micro-computed tomography, and energy dispersive X-ray spectroscopy to evaluate parameters of interest in facet joint degeneration such as elemental composition, cartilage layer thickness and cell density, calcification zone thickness, subchondral bone portion, and trabecular bone porosity. These microstructural analyses demonstrate fragmentation, cracking, and destruction of the cartilage layer, a thickened calcification zone, localized calcification areas, and cell cluster formation as pathological manifestations of facet joint degeneration. The detailed description of these microstructural changes is critical for a comprehensive understanding of the pathology of facet joint degeneration, as well as the subsequent development and efficacy analysis of regenerative treatment strategies.
  • Friedmann, Andrea; Goehre , Felix; Ludtka, Christopher; Mendel, Thomas; Meisel, Hans-Joerg; Heilmann, Andreas; Schwan, Stefan (2017)
    Degeneration of intervertebral disc (IVD) tissue is characterized by several structural changes that result in variations in disc physiology and loss of biomechanical function. The complex process of degeneration exhibits highly intercorrelated biomechanical, biochemical, and cellular interactions. There is currently some understanding of the cellular changes in degenerated intervertebral disc tissue, but microstructural changes and deterioration of the tissue matrix has previously been rarely explored. In this work, sequestered IVD tissue was successfully characterized using histology, light microscopy, and scanning electron microscopy (SEM) to quantitatively evaluate parameters of interest for intervertebral disc degeneration (IDD) such as delamination of the collagenous matrix, cell density, cell size, and extra cellular matrix (ECM) thickness. Additional qualitative parameters investigated included matrix fibration and irregularity, neovascularization of the IVD, granular inclusions in the matrix, and cell cluster formation. The results of this study corroborated several previously published findings, including those positively correlating female gender and IVD cell density, age and cell size, and female gender and ECM thickness. Additionally, an array of quantitative and qualitative investigations of IVD degeneration could be successfully evaluated using the given methodology, resin-embedded SEM in particular. SEM is especially practical for studying micromorphological changes in tissue, as other microscopy methods can cause artificial tissue damage due to the preparation method. Investigation of the microstructural changes occurring in degenerated tissue provides a greater understanding of the complex process of disc degeneration as a whole. Developing a more complete picture of the degenerative changes taking place in the intervertebral disc is crucial for the advancement and application of regenerative therapies based on the pathology of intervertebral disc degeneration. (C) 2016 Elsevier Ltd. All rights reserved.