https://repository-scidap.cvtisr.sk//jspui/handle/123456789/7 Fri, 01 Jul 2022 05:40:53 GMT 2022-07-01T05:40:53Z https://repository-scidap.cvtisr.sk//jspui/handle/123456789/33 Title: An Investigation of the Bacterial Influence of Acidithiobacillus Thiooxidans on Concrete Composites Authors: Ondrejka Harbulakova, Vlasta; Estoková, Adriana; Ľuptáková, Alena Abstract: Vegetation and microorganisms present the biological factors that deteriorate concrete. These problems are very visible in places like sewage, underground and hydraulic structures, chemical plants, industrial structures, liquid-containing structures, agricultural structures or marine environments. The most significant biodeteriogens are the sulphur-oxidising bacteria Acidithiobacillus thiooxidans (A. thiooxidans) and the sulphatereducing bacteria (Desulfovibrio spp.) that are responsible for the so-called sulphuretum consortium. Microorganisms that produce sulphuric acid accelerate the deterioration of concrete sewer pipes in a process termed Microbially Induced Concrete Corrosion (MIC). The paper considers the assessment of the release of calcium and silicon from concrete composites with and without coal fly ash by sulphur-oxidizing bacteria. The concrete mixture contained coal fly ash as 5 wt. % and wt. 10 % cement replacement. Prepared composites were exposed to an aggressive microbial environment under laboratory conditions for 3 months. The pH values were measured and studied during this time period. A different resistance against MIC was observed for the concrete composites of different compositions. The highest amount of calcium leached-out from the concrete was in the case of the composites where 10 % cement was replaced by fly ash. Sun, 01 Jul 2018 00:00:00 GMT https://repository-scidap.cvtisr.sk//jspui/handle/123456789/33 2018-07-01T00:00:00Z https://repository-scidap.cvtisr.sk//jspui/handle/123456789/32 Title: Mechanochemically Synthesised Coal-Based Magnetic Carbon Composites for Removing As(V) and Cd(II) from Aqueous Solutions Authors: Zubrík, Anton; Matík, Marek; Lovás, Michal; Danková, Zuzana; Kaňuchová, Mária; Hredzák, Slavomír; Briančin, Jaroslav; Šepelák, Vladimír Abstract: The continued decrease in water quality requires new advances in the treatment of wastewater, including the preparation of novel, effective, environmentally friendly, and affordable sorbents of toxic pollutants. We introduce a simple non-conventional mechanochemical synthesis of magnetically responsive materials. Magnetic lignite and magnetic char were prepared by high-energy ball co-milling from either raw Slovak lignite or coal-based char together with a ferrofluid. The products were characterised by X-ray diffraction, electron microscopy, 57Fe Mössbauer spectroscopy, X-ray photoelectron spectroscopy (XPS), volumetric magnetic susceptibility, and low-temperature nitrogen adsorption, and both magnetic carbons were comparatively tested as potential sorbents of As(V) oxyanions and Cd(II) cations in aqueous solutions. The magnetic char was an excellent sorbent of As(V) oxyanions (Qm = 19.9 mg/g at pH 3.9), whereas the magnetic lignite was less effective. The different sorption properties towards arsenic anions may have been due to different oxidation states of iron on the surfaces of the two magnetic composites (determined by XPS), although the overall state of iron monitored by Mössbauer spectroscopy was similar for both samples. Both magnetic composites were effective sorbents for removing Cd(II) cations (Qm (magnetic lignite) = 70.4 mg/g at pH 6.5; Qm (magnetic char) = 58.8 mg/g at pH 6.8). View Full-Text Tue, 01 Jan 2019 00:00:00 GMT https://repository-scidap.cvtisr.sk//jspui/handle/123456789/32 2019-01-01T00:00:00Z https://repository-scidap.cvtisr.sk//jspui/handle/123456789/26 Title: (–)-Epicatechin Reduces the Blood Pressure of Young Borderline Hypertensive Rats During the Post-Treatment Period Authors: Kluknavský, Michal; Bališ, Peter; Skratek, Martin; Manka, Ján; Bernátová, Iveta Abstract: This study investigated the effects of (–)-epicatechin (Epi) in young male borderline hypertensive rats (BHR) during two weeks of treatment (Epi group, 100 mg/kg/day p.o.) and two weeks post treatment (PE group). Epi reduced blood pressure (BP), which persisted for two weeks post treatment. This was associated with delayed reduction of anxiety-like behaviour. Epi significantly increased nitric oxide synthase (NOS) activities in the aorta and left heart ventricle (LHV) vs. the age-matched controls without affecting the brainstem and frontal neocortex. Furthermore, Epi significantly reduced the superoxide production in the aorta and relative content of iron-containing compounds in blood. Two weeks post treatment, the NOS activities and superoxide productions in the heart and aorta did not differ from the age-matched controls. The gene expressions of the NOSs (nNOS, iNOS, eNOS), nuclear factor erythroid 2-related factor 2 (Nrf2), and peroxisome proliferator-activated receptor-γ (PPAR-γ) remained unaltered in the aorta and LHV of the Epi and PE groups. In conclusion, while Epi-induced a decrease of the rats’ BP persisted for two weeks post treatment, continuous Epi treatments seem to be necessary for maintaining elevated NO production as well as redox balance in the heart and aorta without changes in the NOSs, Nrf2, and PPAR-γ gene expressions. Wed, 01 Jan 2020 00:00:00 GMT https://repository-scidap.cvtisr.sk//jspui/handle/123456789/26 2020-01-01T00:00:00Z