Confocal micro-beam X-ray fluorescence analysis (confocal micro-XRF) is a non-destructive analytical tool for investigation of sample composition that enables acquiring three-dimensionally resolved information. This work describes a calibration procedure of a laboratory confocal micro-XRF setup, which leads to determination of its characteristic parameters. The calibration is performed using a tabletop confocal micro-XRF spectrometer designed recently at the Czech Technical University in Prague. The calibration procedure performed within this work comprises the essential steps of the setup characterization: excitation spectrum calculation, experimental determination of energy-dependent confocal volume size and integral sensitivity and calculation of the spectrometer sensitivity function. The results of the setup calibration will be used for development of a procedure enabling quantitative evaluation of the measured depth profiles.
- MeSH
- algoritmy MeSH
- fluorescence * MeSH
- kalibrace MeSH
- lidé MeSH
- rentgenové záření MeSH
- spektrometrie rentgenová emisní přístrojové vybavení metody normy MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- hodnotící studie MeSH
Inadequate cross-linking between collagen lamellae is a characteristic feature of keratoconus corneas. The formation of covalent bonds between collagen and elastin fibrils, which maintain the biomechanical properties of the cornea, is mediated by the cuproenzyme lysyl oxidase and four lysyl oxidase-like enzymes. The aim of this study was to determine the distribution of lysyl oxidase and the total lysyl oxidase activity (lysyl oxidase and the four lysyl oxidase-like enzymes) in control and keratoconic corneas. Seven control and eight keratoconic corneas were used for the imunohistochemical detection of lysyl oxidase in corneal cryosections using two different antibodies. The total lysyl oxidase activity in the culture medium of corneal fibroblasts from six explanted keratoconic and four control corneas was measured using a fluorometric assay in the presence and absence of the lysyl oxidase inhibitor beta-aminopropionitrile and determined as the production of H(2)O(2) in nM per μg of total protein. In the control tissue, the most intense signal for lysyl oxidase was present in the corneal epithelium, in which perinuclear dots brightly projecting from more or less homogenous cytoplasmic staining may represent the lysyl oxidase propeptide. Less intense staining was present in keratocytes, the extracellular matrix and in the corneal endothelium. The epithelium of the limbus and the perilimbal conjunctiva showed intense to very intense staining. The distribution of lysyl oxidase was clearly decreased in at least five of the eight keratoconic specimens. The most marked signal reduction was observed in the stromal matrix and in keratocytes. Moreover, the signal in pathological specimens revealed a more irregular pattern, including the presence of intra- and extracellular clumps in the epithelium. Interestingly, endothelial cells showed no or very weak staining in areas just beneath negative stromal tissue. The mean activity of total lysyl oxidase in the keratoconic samples (2.60 ± 2.23 nM H(2)O(2)/μg of total protein) was more than 2.5-fold lower than in control tissue (6.83 ± 2.53 nM H(2)O(2)/μg of total protein), and the decrease was statistically significant (p = 0.0178). The location of lysyl oxidase in the healthy cornea, limbus and perilimbal conjunctiva was described. We hypothesize that the restricted lysyl oxidase distribution in keratoconic corneas, and particularly the decrease of total lysyl oxidase activity in cultured keratoconic fibroblasts, is one potential reason for the inadequate collagen cross-linking that is a hallmark of this disease.
- MeSH
- dospělí MeSH
- fluorescenční protilátková technika nepřímá MeSH
- keratokonus enzymologie patologie chirurgie MeSH
- konjunktiva enzymologie MeSH
- kultivované buňky MeSH
- lidé středního věku MeSH
- lidé MeSH
- limbus corneae enzymologie MeSH
- lysyloxidasa metabolismus MeSH
- mladiství MeSH
- mladý dospělý MeSH
- oxidoreduktasy aminokyselin metabolismus MeSH
- rohovka enzymologie MeSH
- rohovkové keratocyty enzymologie MeSH
- senioři MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
In this paper, three Monte Carlo codes were tested for electron transport in various materials. MCNPX (version 2.4.0), Penelope (version 2003) and EGSnrc codes were used for modeling simple problems. These problems were focused on bremsstrahlung, energy deposition in matter, electron ranges and production of secondary electrons by gamma radiation. The electrons were primary particles, except in the last exercise, where photons were used. Various materials, e.g., water, lead and tungsten were used. The energy of the primary particles was within the energy range from 20 to 450 keV. The simulation results were compared with each other.
This paper deals with an investigation of ceramic archaeological finds with the use of in-situ X-ray fluorescence analysis. Firstly, three configurations of X-ray fluorescence analyzers constructed and used at the Czech Technical University in Prague are described and compared for use in a non-destructive survey of siliceous materials. Detection limits, depth of analysis, the relation of the analyzed area, the homogeneity of the samples, and variations in the element concentrations are discussed. Secondly, many shards of postmediaeval pottery from Southern Moravia are analyzed with X-ray fluorescence analysis and some of them also with electron microprobe analysis. Selected results are described.
- MeSH
- barvicí látky analýza MeSH
- dějiny středověku MeSH
- difrakce rentgenového záření metody MeSH
- keramika analýza MeSH
- rukopisy jako téma dějiny MeSH
- sochařství dějiny MeSH
- spektrometrie rentgenová emisní metody MeSH
- Check Tag
- dějiny středověku MeSH
- Publikační typ
- časopisecké články MeSH
- historické články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
In this work we present the application of X-ray fluorescence analysis (XRFA) in an investigation of the Land Register and the Register of the Court of the Kingdom of Bohemia and the manuscript of the Homiliary of the Opatovice Monastery from the 12th century. Radionuclide sources emitting radiation at an appropriate energy level and an X-ray tube were used to excite the characteristic radiation. A spectrometric Si(Li) detector and a Si-PIN detector with Peltier cooling were used to detect the excited characteristic radiation. Several types of pigments were identified and compositions of inks used within almost 5 centuries in the offices at the Prague Castle were determined.
- MeSH
- barvicí látky analýza MeSH
- dějiny středověku MeSH
- difrakce rentgenového záření metody MeSH
- rukopisy jako téma dějiny MeSH
- Check Tag
- dějiny středověku MeSH
- Publikační typ
- časopisecké články MeSH
- historické články MeSH
- Geografické názvy
- Česká republika MeSH
The method for depth-related radionuclide distribution was evolved for approximate determination of the spatial lay-out of radionuclides in materials. The method is based on different attenuation coefficients for various energies of gamma radiation. For each material, the attenuation coefficient decreases with rising energy of radiation. It is therefore possible to assess the location of radionuclides in a material owing to attenuation on the track which a photon has to pass through the material. In this case, gamma lines with energies 609 and 1764 keV produced by nuclide (214)Bi were used for depth-related radionuclide distribution. This application should be suitable for locating radionuclides in the walls of buildings where high dose rates from gamma radiation occur. These doses are caused by natural radionuclides, mainly radium daughters. The presence of radionuclides in houses poses a high risk associated with inhalation of radon and its decay products. For suitable remediation, it is necessary to know the radionuclide depth distribution.
X-ray fluorescence analysis with an evaluation of the Kalpha/Kbeta or Lalpha/Lbeta count rate ratios enables a layered structure to be recognized, because the measured ratio of two lines of one element depends on the depth distribution of this element in the analyzed objects. Several specimens consisting of layers of various pigments were analyzed to demonstrate the possibilities of the proposed technique. Then the Lalpha/Lbeta technique was applied in an investigation of cinnabar distribution in mediaeval manuscripts.
