Pokročilé instrumentace a metody pro charakterizace materiálů


Recent Submissions

Now showing 1 - 5 of 44
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    Role of ciliopathy protein TMEM107 in eye development: insights from a mouse model and retinal organoid
    (Life Science Alliance, 2023-10-20) Dubaic, Marija; Pešková, Lucie; Hampl, Marek; Weissová, Kamila; Celiker, Canan; Shylo, Natalya A.; Hrubá, Eva; Kavková, Michaela; Zikmund, Tomáš; Weatherbee, Scott Donald; Kaiser, Jozef; Bárta, Tomáš; Buchtová, Marcela
    Primary cilia, enriched in receptors and signaling molecules, serve as vital signaling hubs responsive to stimuli and are implicated in human diseases like retinopathies. TMEM107, localized to the transition zone of primary cilia, is linked to conditions such as Joubert and Meckel–Gruber syndromes, and its deficiency hinders cilia formation and early vertebrate eye development in retinal organoids.
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    Calcareous nannofossil assemblage in paintings chalk ground for provenance analysis: three original paintings compared to european source materials
    (Springer Nature, 2023-07-07) Jaques, Victory; Holcová, Katarína
    Chalk has been used since Antiquity for various purposes, and since Gothic for preparatory layers of painted cultural heritage objects. Several materials are called chalk in Cultural Heritage, but this work especially focuses on chalk composed of calcareous nannofossils (up to 98%). These are fossil remains of photoautotrophic algae generally smaller than 30 & mu;m. They are mainly visible as platelets of various shapes under a cross-polarised or scanning electron microscope. The provenance of chalk can be determined using calcareous nannofossils due to their well-known paleobiogeographic localities. They are already used as proxies since the 90s in Cultural Heritage, but rarely for paintings. In this work, 6 chalk historical mining areas were chosen: Germany (Ruegen), France (Champagne, Meudon), Belgium (Mons), England (Norfolk) and Italy (Bologna). Natural and processed chalk were used as reference materials and compared to 3 original paintings. The difference between the chalks calcareous nannofossil assemblages was shown using multivariate statistical analysis based on species relative abundance. Marker nannofossil species were defined for each chalk locality. One painting material could not be originated due to the preservation of its nannofossils assemblage, but the origins of the rock chalk material from the two other paintings could be geographically located in France.
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    A previously uncharacterized Factor Associated with Metabolism and Energy (FAME/C14orf105/CCDC198/1700011H14Rik) is related to evolutionary adaptation, energy balance, and kidney physiology
    (NATURE PORTFOLIO, 2023-05-29) Kaiser, Markéta; Zikmund, Tomáš; Kavková, Michaela; Kaiser, Jozef
    In this study we use comparative genomics to uncover a gene with uncharacterized function (1700011H14Rik/C14orf105/CCDC198), which we hereby name FAME (Factor Associated with Metabolism and Energy). We observe that FAME shows an unusually high evolutionary divergence in birds and mammals. Through the comparison of single nucleotide polymorphisms, we identify gene flow of FAME from Neandertals into modern humans. We conduct knockout experiments on animals and observe altered body weight and decreased energy expenditure in Fame knockout animals, corresponding to genome-wide association studies linking FAME with higher body mass index in humans. Gene expression and subcellular localization analyses reveal that FAME is a membrane-bound protein enriched in the kidneys. Although the gene knockout results in structurally normal kidneys, we detect higher albumin in urine and lowered ferritin in the blood. Through experimental validation, we confirm interactions between FAME and ferritin and show co-localization in vesicular and plasma membranes.
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    Spectral library transfer between distinct Laser-Induced Breakdown Spectroscopy systems trained on simultaneous measurements
    (Royal Society of Chemistry, 2023-04-05) Vrábel, Jakub; Képeš, Erik; Nedělník, Pavel; Buday, Jakub; Cempírek, Jan; Pořízka, Pavel; Kaiser, Jozef
    The mutual incompatibility of distinct spectroscopic systems is among the most limiting factors in Laser-Induced Breakdown Spectroscopy (LIBS). The cost related to setting up a new LIBS system is increased, as its extensive calibration is required. Solving the problem would enable inter-laboratory reference measurements and shared spectral libraries, which are fundamental for other spectroscopic techniques. We study a simplified version of this challenge where LIBS systems differ only in used spectrometers and collection optics but share all other parts of the apparatus, and collect spectra simultaneously from the same plasma plume. Extensive datasets measured as hyperspectral images of heterogeneous rock sample are used to train machine learning models that can transfer spectra between systems. The transfer is realized by a composed model that consists of a variational autoencoder (VAE) and a multilayer perceptron (MLP). The VAE is used to create a latent representation of spectra from the Primary system. Subsequently, spectra from the Secondary system are mapped to corresponding locations in the latent space by the MLP. The transfer is evaluated by several figures of merit (Euclidean and cosine distances, both spatially resolved; k-means clustering of transferred spectra). We demonstrate the viability of the method and compare it to several baseline approaches of varying complexity.
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    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.