Pokročilé instrumentace a metody pro charakterizace materiálů

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Application of Dual-target Computed Tomography for Material Decomposition of Low-Z Materials
(SPRINGER/PLENUM PUBLISHERS, 2024-06-01) Mikuláček, Pavel; Zemek, Marek; Štarha, Pavel; Zikmund, Tomáš; Kaiser, Jozef
The extension of conventional computed tomography known as spectral computed tomography involves utilizing the variations in X-ray attenuation, driven by spectral and material dependencies. This technique enables the virtual decomposition of scanned objects, revealing their elemental constituents. The resultant images provide quantitative information, such as material concentration within the scanned volume. Enhancements in results are achievable through methods that capitalize on the strong correlation among decomposed images, effectively minimizing noise and artifacts. The Rigaku nano3DX submicron tomograph uses a dual-target source, which allows the generation of two distinct X-ray spectra through different target materials. This configuration holds promise for high-resolution applications in spectral tomography, particularly for low-Z materials, where it offers high contrast in the acquired images. The potential of this setup in the context of spectral computed tomography is explored in this contribution, delving into its applications for materials characterized by low atomic numbers.
3D atlas of the human fetal chondrocranium in the middle trimester
(NATURE PORTFOLIO, 2024-06-13) Kaiser, Markéta; Zikmund, Tomáš; Siddharth, Vora; Metscher, Brian; Adameyko, Igor; Richman, Joy M.; Kaiser, Jozef
The chondrocranium provides the key initial support for the fetal brain, jaws and cranial sensory organs in all vertebrates. The patterns of shaping and growth of the chondrocranium set up species-specific development of the entire craniofacial complex. The 3D development of chondrocranium have been studied primarily in animal model organisms, such as mice or zebrafish. In comparison, very little is known about the full 3D human chondrocranium, except from drawings made by anatomists many decades ago. The knowledge of human-specific aspects of chondrocranial development are essential for understanding congenital craniofacial defects and human evolution. Here advanced microCT scanning was used that includes contrast enhancement to generate the first 3D atlas of the human fetal chondrocranium during the middle trimester (13 to 19 weeks). In addition, since cartilage and bone are both visible with the techniques used, the endochondral ossification of cranial base was mapped since this region is so critical for brain and jaw growth. The human 3D models are published as a scientific resource for human development.
Ch(O)P-CT: quantitative morphometrical analysis of the Hindbrain Choroid Plexus by X-ray micro-computed tomography
(BMC, 2024-01-24) Parobková, Viktória; Kompaníková, Petra; Lázňovský, Jakub; Kavková, Michaela; Hampl, Marek; Buchtová, Marcela; Zikmund, Tomáš; Kaiser, Jozef; Bryja, Vítězslav
The Hindbrain Choroid Plexus is a complex, cerebrospinal fluid-secreting tissue that projects into the 4th vertebrate brain ventricle. Despite its irreplaceability in the development and homeostasis of the entire central nervous system, the research of Hindbrain Choroid Plexus and other Choroid Plexuses has been neglected by neuroscientists for decades. One of the obstacles is the lack of tools that describe the complex shape of the Hindbrain Choroid Plexus in the context of brain ventricles. Here we introduce an effective tool, termed Ch(O)P-CT, for the noninvasive, X-ray micro-computed tomography-based, three-dimensional visualization and subsequent quantitative spatial morphological analysis of developing mouse Hindbrain Choroid Plexus. Ch(O)P-CT can reliably quantify Hindbrain Choroid Plexus volume, surface area, length, outgrowth angle, the proportion of the ventricular space occupied, asymmetries and general shape alterations in mouse embryos from embryonic day 13.5 onwards. We provide evidence that Ch(O)P-CT is suitable for the unbiased evaluation and detection of the Hindbrain Choroid Plexus alterations within various mutant embryos. We believe, that thanks to its versatility, quantitative nature and the possibility of automation, Ch(O)P-CT will facilitate the analysis of the Hindbrain Choroid Plexus in the mouse models. This will ultimately accelerate the screening of the candidate genes and mechanisms involved in the onset of various Hindbrain Choroid Plexus-related diseases.
Design of tailored biodegradable implants: The effect of voltageon electrodeposited calcium phosphate Coatings on puremagnesium
(The American Ceramic Society, 2019-01-01) Horynová, Miroslava; Remešová, Michaela; Klakurková, Lenka; Dvořák, Karel; Ročňáková, Ivana; Yan, Shaokun; Čelko, Ladislav; Song, Guang-Ling
Magnesium, as a biodegradable metal, offers great potential for use as a tempo-rary implant material, which dissolves in the course of bone tissue healing. It cansufficiently support the bone and promote the bone healing process. However, thecorrosion resistance of magnesium implants must be enhanced before its applica-tion in clinical practice. A promising approach of enhancing the corrosion resis-tance is deposition of bioactive coating, which can reduce the corrosion rate ofthe implants and promote bone healing. Therefore, a welldesigned substratecoat-ing system allowing a good control of the degradation behavior is highly desir -able for tailored implants for specific groups of patients with particular needs. Inthis con tribution, the influence of coating formation conditions on the charact eris-tics of potentiostatically elect rodeposited CaP coatings on magnesium substratewas evaluated. Results showed that potential variation led to formation of coat-ings with the same chemical composition, but very different morphologies.Parameters that mostly influence the coating performance, such as the thickness,uniformity, deposits size, and orientation, varied from produced coating to coat-ing. These characteristics of CaP coatings on magnesium were controlled by coat-ing formation potential, and it was demonstrated that the electrodeposition couldbe a promising coating technique for production of tailored magnesium CaPimplants.
Fatigue behaviour of titanium scaffolds with hierarchical porosity produced by material extrusion additive manufacturing
(Elsevier, 2023-01-26) Slámečka, Karel; Kashimbetova, Adelia; Pokluda, Jaroslav; Zikmund, Tomáš; Kaiser, Jozef; Montufar Jimenez, Edgar Benjamin; Čelko, Ladislav
Metallic porous structures (scaffolds) produced by additive manufacturing represent an important class of personalised implants used in load-bearing orthopaedic applications. As such, their fatigue performance must be excellent to prevent the need for revision surgery. This paper provides insight into the high-cycle fatigue behaviour of novel titanium scaffolds with hierarchical porosity and properties comparable to those of human bone that were produced by direct ink writing (DIW) and tested under cyclic loading typical for bone implants. Opposite to traditional expectations in the field of metal fatigue, scaffolds produced with an open intrastrand pore network (14.3%) endured nearly an order of magnitude more cycles than those with relatively compact strands (5.9%) and their normalized fatigue strength (62% of their yield strength in one milion cycles) was competitive with many current titanium scaffolds produced by other additive manufacturing technologies. Improved fatigue performance was related to fatigue crack growth shielding effects that reduced the crack growth rate, prolonged the crack path, and increased energy absorption. Consequently, these novel hierarchically porous titanium structures prepared by DIW can serve safely under cyclic loading conditions, and at the same time can provide multiple open porosity-related functionalities in advanced biomedicine and other industrial sectors.

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