Pokročilé instrumentace a metody pro charakterizace materiálů

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    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.
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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.
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    High-resolution micro-CT for 3D infarct characterization and segmentation in mice stroke models
    (Nature Portfolio, 2022-10-19) Pinto, Raquel; Matula, Jan; Gomez Lazaro, Maria; Sousa, Mafalda; Lobo, Andrea; Zikmund, Tomáš; Kaiser, Jozef; R. Gomes, Joo
    Characterization of brain infarct lesions in rodent models of stroke is crucial to assess stroke pathophysiology and therapy outcome. Until recently, the analysis of brain lesions was performed using two techniques: (1) histological methods, such as TTC (Triphenyltetrazolium chloride), a time-consuming and inaccurate process; or (2) MRI imaging, a faster, 3D imaging method, that comes at a high cost. In the last decade, high-resolution micro-CT for 3D sample analysis turned into a simple, fast, and cheaper solution. Here, we successfully describe the application of brain contrasting agents (Osmium tetroxide and inorganic iodine) for high-resolution micro-CT imaging for fine location and quantification of ischemic lesion and edema in mouse preclinical stroke models. We used the intraluminal transient MCAO (Middle Cerebral Artery Occlusion) mouse stroke model to identify and quantify ischemic lesion and edema, and segment core and penumbra regions at different time points after ischemia, by manual and automatic methods. In the transient-ischemic-attack (TIA) mouse model, we can quantify striatal myelinated fibers degeneration. Of note, whole brain 3D reconstructions allow brain atlas co-registration, to identify the affected brain areas, and correlate them with functional impairment. This methodology proves to be a breakthrough in the field, by providing a precise and detailed assessment of stroke outcomes in preclinical animal studies.
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    Laser-based techniques: Novel tools for the identification and characterization of aged microplastics with developed biofilm
    (Elsevier, 2023-02-01) Pořízka, Pavel; Brunnbauer, Lukas; Porkert, Michaela; Rozman, Ula; Marolt, Gregor; Holub, Daniel; Kizovský, Martin; Benešová, Markéta; Samek, Ota; Limbeck, Andreas; Kaiser, Jozef; Kalčíková, Gabriela
    Microplastics found in the environment are often covered with a biofilm, which makes their analysis difficult. Therefore, the biofilm is usually removed before analysis, which may affect the microplastic particles or lead to their loss during the procedure. In this work, we used laser-based analytical techniques and evaluated their performance in detecting, characterizing, and classifying pristine and aged microplastics with a developed biofilm. Five types of microplastics from different polymers were selected (polyamide, polyethylene, polyethylene terephthalate, polypropylene, and polyvinyl chloride) and aged under controlled conditions in freshwater and wastewater. The development of biofilm and the changes in the properties of the microplastic were evaluated. The pristine and aged microplastics were characterized by standard methods (e.g., optical and scanning electron microscopy, and Raman spectroscopy), and then laser-induced breakdown spectroscopy (LIBS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were used. The results show that LIBS could identify different types of plastics regardless of the ageing and major biotic elements of the biofilm layer. LA-ICP-MS showed a high sensitivity to metals, which can be used as markers for various plastics. In addition, LA-ICP-MS can be employed in studies to monitor the adsorption and desorption (leaching) of metals during the ageing of microplastics. The use of these laser-based analytical techniques was found to be beneficial in the study of environmentally relevant microplastics.
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    X-ray microtomography imaging of craniofacial hard tissues in selected reptile species with different types of dentition
    (Oxford University Press, 2022-03-07) Kavková, Michaela; Šulcová, Marie; Zikmund, Tomáš; Pyszko, Martin; Kaiser, Jozef; Buchtová, Marcela
    Background Reptiles exhibit a large heterogeneity in teeth morphology. The main variability comprises the different tooth shape, the type of tooth attachment to the underlying bone, or the ability to replace the teeth. Findings Here, we provide full datasets of microtomography scans and 3D models of reptilian dentitions and skulls. We selected representative species for each of 9 reptilian families on the basis of their characteristic dental features. Because there are >= 4 different types of tooth-bone attachments, ranging from the mammalian-like thecodont attachment found in crocodilians to the simple acrodont implantation observed in some lizards, we aimed to evaluate species with different types of tooth-bone attachments. Moreover, another interesting feature varying in reptilian species is the complexity of tooth shape or the number of tooth generations, which can be associated with the type of tooth attachment to the jawbone. Therefore, selected model species also include animals with distinct tooth morphology along the jaw or different number of tooth generations. The development of tooth attachment and relationship of the tooth to the jaw can be further analysed in detail on a large collection of pre-hatching stages of chameleon. Next, we introduce different possibilities for how these datasets can be further used to study tooth-bone relationships or tooth morphology in 3D space. Moreover, these datasets can be valuable for additional morphological and morphometric analyses of reptilian skulls or their individually segmented skeletal elements. Conclusions Our collection of microcomputed tomography scans can bring new insight into dental or skeletal research. The broad selection of reptilian species, together with their unique dental features and high quality of these scans including complete series of developmental stages of our model species and provide large opportunities for their reuse. Scans can be further used for virtual reality, 3D printing, or in education.