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3. Microstructure of interfacial transition zone between PET fibres and cement paste

Creator:
Machovič, Vladimír, Lapčák, Ladislav, Borecká, Lenka, Miloslav Lhotka, Andertová, Jana, Kopecký, Lubomír, and Mišková, Linda
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Geologie. Meteorologie. Klimatologie, spektroskopie, spectroscopy, fibre reinforced concrete, Raman mapping microspectroscopy, 7, and 551
Language:
English
Description:
Considerable amount of waste in the form of polyethylene terephthalate (PET) bottles could be utilized in the form of dispersed microreinforcement in concrete. PET fibres, however, have poor wettability and adhesion to cement paste, which can be modified by alkaline hydrolysis with sodium hydroxide at elevated temperature. The alkaline treatment was used to increase fibre surface, which was followed by changes in the structure of the interfacial transition zone (ITZ) and interfacial bond between fibre and cementitious matrix. Raman microspectroscopy mapping was employed to study microstructural changes of ITZ within the distance 0 - 250 μm from a PET fibre. The band at 357 cm-1 corresponding to the Ca-O bond vibration in portlandite was used to determine its distribution. For determination of the relative abundance of ettringite, the SO42- stretching vibration at 987 cm-1 was used. The most intensive bands of portlandite and ettringite were found within the distance 0 - 50 μm from an unmodified PET fibre. Besides the elevated concentration of these minerals, abundant pores occur in this region. In the case of alkaline modified PET fibres the ITZ zone was not found., Vladimír Machovič, Ladislav Lapčák, Lenka Borecká, Miloslav Lhotka, Jana Andertová, Lubomír Kopecký and Linda Mišková., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4. The relationships between quantitative MR parameters in hippocampus in healthy subjects and patients with temporal lobe epilepsy

Creator:
Wagnerová, D., Vít Herynek, Monika Dezortová, Petr Marusič, Pavel Kršek, Josef Zámečník, Filip Jírů, Antonín Škoch, and Milan Hájek
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, temporální epilepsie, spektroskopie, temporal epilepsy, spectroscopy, temporal lobe epilepsy, 1H-MR spectroscopy, MR diffusometry, T2 relaxometry, correlations, 14, and 612
Language:
English
Description:
We introduce a new magnetic resonance (MR) method based on a pixel-by-pixel image processing to examine relationships between metabolic and structural processes in the pathologic hippocampus. The method was tested for lateralization of the epileptogenic zone in patients with temporal lobe epilepsy (TLE). Twenty patients with drug-resistant TLE and fifteen healthy controls were examined at 3T. The measurement protocol contained T2-weighted MR images, spectroscopic imaging, diffusion tensor imaging and T2 relaxometry. Correlations between quantitative MR parameters were calculated on a pixelby- pixel basis using the CORIMA program which enables automated pixel identification in the normal tissue according to control data. All MR parameters changed in the anteroposterior direction in the hippocampus and correlation patterns and their slopes differed between patients and controls. Combinations of T2 relaxation times with metabolite values represent the best biomarkers of the epileptogenic zone. Correlations with mean diffusivity did not provide sufficiently accurate results due to diffusion image distortions. Quantitative MR analysis noninvasively provides a detailed description of hippocampal pathology and may represent complementary tool to the standard clinical protocol. However, the automated processing should be carefully monitored in order to avoid possible errors caused by MR artifacts., D. Wagnerová, V. herynek, M. Dezortová, P. Marusič, P. Kršek, J. Zámečník, F. Jírů, A. Škoch, M. Hájek., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public