Al2O3
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BACKGROUND: The objective of this prospective randomized monocentric study is to compare the speed and quality of interbody fusion of implanted porous Al2O3 (aluminium oxide) cages with PEEK (polyetheretherketone) cages in ACDF (anterior cervical discectomy and fusion). MATERIALS AND METHODS: A total of 111 patients were enrolled in the study, which was carried out between 2015 and 2021. The 18-month follow-up (FU) was completed in 68 patients with an Al2O3 cage and 35 patients with a PEEK cage in one-level ACDF. Initially, the first evidence (initialization) of fusion was evaluated on computed tomography. Subsequently, interbody fusion was evaluated according to the fusion quality scale, fusion rate and incidence of subsidence. RESULTS: Signs of incipient fusion at 3 months were detected in 22% of cases with the Al2O3 cage and 37.1% with the PEEK cage. At 12-month FU, the fusion rate was 88.2% for Al2O3 and 97.1% for PEEK cages, and at the final FU at 18 months, 92.6% and 100%, respectively. The incidence of subsidence was observed to be 11.8% and 22.9% of cases with Al2O3 and PEEK cages, respectively. CONCLUSIONS: Porous Al2O3 cages demonstrated a lower speed and quality of fusion in comparison with PEEK cages. However, the fusion rate of Al2O3 cages was within the range of published results for various cages. The incidence of subsidence of Al2O3 cages was lower compared to published results. We consider the porous Al2O3 cage as safe for a stand-alone disc replacement in ACDF.
- MeSH
- diskektomie * MeSH
- ketony MeSH
- lidé MeSH
- oxid hlinitý * MeSH
- polyethylenglykoly MeSH
- poréznost MeSH
- prospektivní studie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- randomizované kontrolované studie MeSH
One of the main mechanisms of nanoparticle toxicity is known to be the generation of reactive oxygen species (ROS) which primarily damage cell membranes. However, very limited data on membrane effects in anaerobic environments (where ROS could not be the cause of membrane damage) are available. In the following study, rumen anaerobe Ruminococcus flavefaciens 007C was used as a bacterial model to assess the potential effects of Al(2)O(3) and TiO(2) nanoparticles on membranes in an anaerobic environment. Fatty acid profiles of cultures after exposure to Al(2)O(3) or TiO(2) nanoparticles were analyzed and compared with the profiles of non-exposed cultures or cultures exposed to bulk materials. Analysis revealed dose-effect changes in membrane composition exclusively when cells were exposed to Al(2)O(3) nanoparticles in a concentration range of 3-5 g/L, but were not present in cultures exposed to bulk material. On the other hand, the tested concentrations of nano-TiO(2) did not significantly affect the membrane profile of the exposed bacterium. The results suggest the possibility that Al(2)O(3) induces changes in bacterial membranes by direct physical interaction, which was supported by TEM image analysis.
- MeSH
- anaerobióza MeSH
- buněčná membrána účinky léků metabolismus MeSH
- mastné kyseliny metabolismus MeSH
- metabolom účinky léků MeSH
- nanočástice toxicita ultrastruktura MeSH
- oxid hlinitý toxicita MeSH
- Ruminococcus účinky léků metabolismus MeSH
- titan toxicita MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
This work studies the feasibility of using repetitive-nano-impact tests with a cube-corner tip and low loads for obtaining quantitative fracture toughness values in thin and brittle coatings. For this purpose, it will be assumed that the impacts are able to produce a cracking, similar to the pattern developed for the classical fracture toughness tests in bulk materials, and therefore, from the crack developed in the repetitive impacts it will be possible to evaluate the suitability of the classical indentation models (Anstins and Laugier) for measuring fracture toughness. However, the length of this crack has to be lower than 10% of the total coating thickness to avoid substrate contributions. For this reason, and in order to ensure a small plastic region localized at the origin of the crack tip, low load values (or small distance between the indenter tip and the surface) have to be used. In order to demonstrate the validity of this technique, repetitive-nano-impact will be done in a fine and dense oxide layer (α-Al2O3), which has been developed on the top of oxide dispersion strengthened (ODS) FeCrAl alloys (PM 2000) by thermal oxidation at elevated temperatures. Moreover, it will be shown how it is possible to know with each new impact the crack geometry evolution from Palmqvist crack to half-penny crack, being able to study the proper evolution of the different values of fracture toughness in terms of both indentation models and as a function of the strain rate, ε̇, decreasing. Thereby, fracture toughness values for α-Al2O3 layer decrease from ~4.40MPam , for high ϵ̇ value (10(3)s(-1)), to ~3.21MPam, for quasi-static ϵ̇ value (10(-3)s(-1)). On the other hand, ϵ̇ a new process to obtain fracture toughness values will be analysed, when the classical indentation models are not met. These values are typically found in the literature for bulk α-Al2O3, demonstrating the use of repetitive-nano-impact tests which not only provide qualitative information about fracture resistance of the materials but it also can be used to obtain quantitative information as fracture toughness values in the case of brittle materials.
Heterogeneous iron species at the mineral/water interface are important catalysts for the generation of reactive oxygen species at circumneutral pH. One significant pathway leading to the formation of such species arises from deposition of dissolved iron onto mineral colloids due to changes in redox conditions. This study investigates the catalytic properties of Fe impregnated on silica, alumina, and titania nanoparticles (as prototypical mineral colloids). Fe impregnation was carried out by immersing the mineral nanoparticles in dilute Fe(II) or Fe(III) solutions at pH 6 and 3, respectively, in an aerobic environment. The uptake of iron per unit surface area follows the order of nTiO2 > nAl2O3 > nSiO2 for both types of Fe precursors. Impregnation of mineral particles in Fe(II) solutions results in predominantly Fe(III) species due to efficient surface-mediated oxidation. The catalytic activity of the impregnated solids to produce hydroxyl radical (·OH) from H2O2 decomposition was evaluated using benzoic acid as a probe compound under dark conditions. Invariably, the rates of benzoic acid oxidation with different Fe-laden particles increase with the surface density of Fe until a critical density above which the catalytic activity approaches a plateau, suggesting active Fe species are formed predominantly at low surface loadings. The critical surface density of Fe varies with the mineral substrate as well as the aqueous Fe precursor. Fe impregnated on TiO2 exhibits markedly higher activity than its Al2O3 and SiO2 counterparts. The speciation of interfacial Fe is analyzed with diffuse reflectance UV-vis analysis and interpretation of the data in the context of benzoic oxidation rates suggests that the surface activity of the solids for ·OH generation correlates strongly with the isolated (i.e., mononuclear) Fe species. Therefore, iron dispersed on mineral colloids is a significant form of reactive iron surfaces in the aquatic environment.
- MeSH
- hydroxylový radikál chemie MeSH
- katalýza MeSH
- koloidy chemie MeSH
- minerály chemie MeSH
- nanočástice MeSH
- oxid hlinitý chemie MeSH
- oxid křemičitý chemie MeSH
- oxidace-redukce MeSH
- peroxid vodíku chemie MeSH
- roztoky chemie MeSH
- titan chemie MeSH
- voda chemie MeSH
- železité sloučeniny chemie MeSH
- železo chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
Nanomaterials or nanoparticles are commonly used in the cosmetics, medicine, and food industries. Many researchers studied the possible side effects of several nanoparticles including aluminum oxide (Al2O3-nps) and zinc oxide nanoparticles (ZnO-nps). Although, there is limited information available on their direct or side effects, especially on the brain, heart, and lung functions. This study aimed to investigate the neurotoxicity, cardiotoxicity, and lung toxicity induced by Al2O3-nps and ZnO-nps or in combination via studying changes in gene expression, alteration in cytokine production, tumor suppressor protein p53, neurotransmitters, oxidative stress, and the histological and morphological changes. Obtained results showed that Al2O3-nps, ZnO-nps and their combination cause an increase in 8-hydroxy-2 ́-deoxyguanosine (8-OHdG), cytokines, p53, oxidative stress, creatine kinase, norepinephrine, acetylcholine (ACh), and lipid profile. Moreover, significant changes in the gene expression of mitochondrial transcription factor-A (mtTFA) and peroxisome proliferator activator receptor-gamma-coactivator-1alpha (PGC-1alpha) were also noted. On the other hand, a significant decrease in the levels of antioxidant enzymes, total antioxidant capacity (TAC), reduced glutathione (GSH), paraoxonase 1 (PON1), neurotransmitters (dopamine - DA, and serotonin - SER), and the activity of acetylcholine esterase (AChE) in the brain, heart, and lung were found. Additionally, these results were confirmed by histological examinations. The present study revealed that the toxic effects were more when these nanoparticle doses are used in combination. Thus, Al2O3-nps and ZnO-nps may behave as neurotoxic, cardiotoxic, and lung toxic, especially upon exposure to rats in combination.
- MeSH
- acetylcholin farmakologie MeSH
- antioxidancia farmakologie MeSH
- kovové nanočástice * toxicita MeSH
- krysa rodu rattus MeSH
- mozek metabolismus MeSH
- nanočástice * toxicita MeSH
- oxid hlinitý toxicita MeSH
- oxid zinečnatý * toxicita MeSH
- oxidační stres MeSH
- plíce metabolismus MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Mycelial basidiomycete cultures on perlite in cryovials survived successfully three successive cycles of freezing, storage in liquid nitrogen (LN) and thawing without noticeable changes. This indicates that using perlite as a carrier for cryopreservation could in most cases overcome difficulties caused by interrupted supply of LN or electric power during the storage. Cultures on perlite can also be reused for successive inoculations.
