The aim of this study was to investigate the concentration level of some major-to-trace elements and toxic minerals and polyphenols (catechin, epicatechin and quercetin) in fruits belonging to different apple cultivars (‘Auriu de Cluj’, ‘Florina’, ‘Generos’, ‘Golden Delicious’, ‘Prima’, ‘Productiv de Cluj’ and ‘Starkrimson’), under specific climate conditions to northwestern Romania. The apple minerals were determined by the inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES) after a preliminary, microwave-assisted, acid digestion. The polyphenols were determined by high performance liquid chromatography (HPLC) with MS/MS detection. According to the obtained results, the edible part of the apple contains many minerals with high relative nutritional value (RNV). The major minerals (Na, K, Ca, Mg and P), minor elements (Cu, Fe, Mn, Sr and Zn) and toxic trace elements (Cd, Cr and Pb) were comparatively identified and quantified. It was found that K (31976 mg/kg) was predominant among the major elements, while Fe (3.68 mg/kg) and Cu (3.57 mg/kg) were comparable. The toxic trace metals (Cd, Cr and Pb) were below the limits of detection (0.01, 0.10 and 0.01 mg/kg, respectively) and did not determine any health risk to consumers. The main polyphenols composition (catechin, epicathechin, quercetin) differs slightly among different cultivars. In ‘Idared’ and ‘Jonathan’ cultivars, the investigated polyphenols are in higher quantities comparing to the others. In all investigated apple cultivars, quercetin was proved to be the major polyphenol, followed by epicathechin and catechin. These results suggest that, regarding only the investigated polyphenols, ‘Idared’ and ‘Jonathan’ cultivars have the highest antioxidant character in all investigated genotypes.
The present work investigates the effect of freeze–thaw cycles on the porosity of three mixtures of road concrete containing blast furnace slag in comparison with two mixtures made with conventional materials. The main technique used in our investigations is nuclear magnetic resonance (NMR) relaxometry. This permitted the extraction of information with respect to the freeze–thaw effect on pore-size distribution, which influences both the mechanical strength and the molecular transport through the material. Moreover, by using this technique, the structure of the air voids was analyzed for the entire pore system in the cement paste and the aggregate particles. The samples under study were first dried in a vacuum oven and then saturated with water or cyclohexane where the distribution of the transverse relaxation times of the protons was recorded. The NMR relaxation measurements were performed on samples extracted from specimens maintained at 300 freeze–thaw cycles and on control samples extracted from specimens kept in water during the freeze–thaw period. Scanning Electron Microscopy (SEM) was used to analyze the microstructure of concrete samples in order to obtain information about the pore sizes and the distance between them. The results from the NMR relaxation measurements were consistent with those obtained by using standard techniques for determining the porosity and the freeze–thaw resistances. The investigations made it possible to establish the optimal composition of blast furnace slag that can be incorporated into road concrete compositions. This non-invasive technique can also complete standard techniques for assessing the porosity and the progress of internal cracks during the freeze–thaw test.
The aim of this study was to investigate the use of natural zeolite as support for microbial community formation during wastewater treatment. Scanning electron microscopy (SEM), thermal decomposition and differential thermogravimetric curves (TGA/DGT) techniques were used for the physicochemical and structural characterization of zeolites. The chemical characterization of wastewater was performed before and after treatment, after 30 days of using stationary zeolite as support. The chemical composition of wastewater was evaluated in terms of the products of nitrification/denitrification processes. The greatest ammonium (NH4+) adsorption was obtained for wastewater contaminated with different concentrations of ammonium, nitrate and nitrite. The wastewater quality index (WWQI) was determined to assess the effluent quality and the efficiency of the treatment plant used, showing a maximum of 71% quality improvement, thus suggesting that the treated wastewater could be discharged into aquatic environments. After 30 days, NH4+ demonstrated a high removal efficiency (higher than 98%), while NO3+ and NO2+ had a removal efficiency of 70% and 54%, respectively. The removal efficiency for metals was observed as follows (%): Mn > Cd > Cr > Zn > Fe > Ni > Co > Cu > Ba > Pb > Sr. Analysis of the microbial diversity in the zeolite samples indicated that the bacteria are formed due to the existence of nutrients in wastewater which favor their formation. In addition, the zeolite was characterized by SEM and the results indicated that the zeolite acts as an adsorbent for the pollutants and, moreover, as a support material for microbial community formation under optimal conditions. Comparing the two studied zeolites, NZ1 (particle size 1–3 mm) was found to be more suitable for wastewater treatment. Overall, the natural zeolite demonstrated high potential for pollutant removal and biomass support for bacteria community growth in wastewater treatment.
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