|
| |
|
|
The determination of material characteristics of natural and artificial stone samples from Marian Column at Hradčany Square in Prague
Slížková, Zuzana ; Zeman, Antonín ; Petráňová, Veronika ; Viani, Alberto ; Pérez-Estébanez, Marta ; Frankeová, Dita ; Ševčík, Radek ; Mácová, Petra ; Janotová, Dana ; Hasníková, Hana ; Niedoba, Krzysztof ; Hauková, Petra
Within the survey before restoration intervention material properties of natural and artificial stones that are part of the Marian Column at Hradcany Square in Prague were determined. 15 samples were subjected to extensive instrumental analysis, whose output is not only chemical and mineralogical composition of the samples, but also the degree of degradation including a description of the porous system and the level of salinity.
|
|
| |
|
|
Determination of drift distortion in SEM micrographs acquired at different magnifications and acquisition times
Petráňová, Veronika ; Koudelka_ml., Petr ; Valach, Jaroslav
In the experimental mechanics wide variety of optical methods including measurement of deformation at reduced length scales using combination of computer vision and scanning electron microscopy (SEM) have been recently applied. One of suitable methods for in-plane measurement of displacements and deformations in the micrographs obtained by SEM is the 2D digital image correlation. In contrast to images obtained in visible spectrum by classical optical devices temporally-varying distortions known as drift distortion are present in the SEM micrographs. These distortions are caused by positional errors of electron beam during scanning process. Magnitude of this effect decreases with higher conductivity of the sample and is also influenced by magnification and scanning time. For this purpose measurement of distortion was performed on a series of micrographs of conductive samples acquired at different magnifications and acquisition times. Surface of each sample was covered with liquid silver to ensure adequate contrast pattern necessary for determination of distortion’s magnitude and distortion magnitudes were assessed.
|
|
| |
|
| |
|
|
A survey of the mortuary in Ostrovec at Velečín
Slížková, Zuzana ; Frankeová, Dita ; Petráňová, Veronika ; Zeman, Antonín ; Hauková, Petra ; Mácová, Petra ; Niedoba, Krzysztof ; Viani, Alberto ; Pérez-Estébanez, Marta ; Zíma, Pavel ; Janotová, Dana
This report presents the results of a survey of the mortuary object in Ostrovec by Velečín which has been selected for testing the samples of plaster developed in the project MK NAKI DF11P01OVV008 (High-performance and compatible lime mortars for extreme application in restoration, repair and preventive maintenance of architectural heritage). The survey focuses on the plinth of the morgue, where the plaster repeatedly freezes and falls off after one winter season. Causes of failure of the repairs plasters and material composition of were examined by following techniques:x-ray diffraction (XRD), thermal analysis (TG), optic and electron microscopy, FTIR and Raman spectroscopy.
|
|
| |
|
|
Assessment of micromechanical properties of trabecular bone using quantitative backscattered electron microscopy
Kytýř, Daniel ; Petráňová, Veronika ; Jiroušek, Ondřej
The biomechanical behaviour of trabecular bone depends not only on its microarchitecture but also on mineral density distribution. Bone mineral density distribution is coupled with mechanical properties of the tissue. In this preliminary study intratrabecular composition of individual trabeculae was investigated. The quantitative backscattered electron microscopy (qBSE) a method based on detection of electrons backscattered from surface layer of the specimen was employed to obtain high resolution images of the transverse sections of a trabecula. From acquired data the element map was created, organic (collagen fibres) to anorganic (hydroxyapatite) material ratio computed and collagen fibres orientation assessed. To conclude qBSE allows to obtain detail information about intratrabecular composition and material properties at the level of individual trabeculae.
|
guest ::
RSS feed.