The analytical performance of the clay paste electrode and graphene paste electrode was compared using square wave voltammetry (SWV) and cyclic voltammetry (CV). The comparison was made on the basis of a paracetamol (PA) determination on both working electrodes. The influence of pH and SWV parameters was investigated. The linear concentration ranges were found to be 6.0 × 10-7-3.0 × 10-5 and 2.0 × 10-6-8.0 × 10-5 mol L-1 for clay paste electrode (ClPE) and graphene paste electrode (GrPE), respectively. The detection and quantification limits were calculated as 1.4 × 10-7 and 4.7 ×10-7 mol L-1 for ClPE and 3.7 × 10-7 and 1.2 × 10-6 mol L-1 for GrPE, respectively. Developed methods were successfully applied to pharmaceutical formulations analyses. Scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to characterize ClPE and GrPE surfaces. Clay composition was examined with wavelength dispersive X-ray (WDXRF).
Compacted bentonites are one of the best sealing and backfilling clays considered for use in Deep Geological Repositories of radioactive wastes. However, an in-depth understanding of their behavior after placement in the repository is required, including if the activity of indigenous microorganisms affects safety conditions. Here we provide an optimized phenol:chloroform based protocol that facilitates higher DNA-yields when other methods failed. To demonstrate the efficiency of this method, DNA was extracted from acetate-treated bentonites compacted at 1.5 and 1.7 g/cm3 densities after 24 months anoxic incubation. Among the 16S rRNA gene sequences identified, those most similar to taxa mediating biogeochemical sulfur cycling included sulfur oxidizing (e.g., Thiobacillus, and Sulfurimonas) and sulfate reducing (e.g., Desulfuromonas and Desulfosporosinus) bacteria. In addition, iron-cycling populations included iron oxidizing (e.g., Thiobacillus and Rhodobacter) plus reducing taxa (e.g., Geobacillus). Genera described for their capacity to utilize acetate as a carbon source were also detected such as Delftia and Stenotrophomonas. Lastly, microscopic analyses revealed pores and cracks that could host nanobacteria or spores. This study highlights the potential role of microbial driven biogeochemical processes in compacted bentonites and the effect of high compaction on microbial diversity in Deep Geological Repositories.
Widely used conazole fungicides (CFs) belong to the most frequently detected pesticides in Central European arable soils. However, data on their environmental behaviour and bioavailability to soil organisms are surprisingly scarce. In the present laboratory microcosm study prochloraz, tebuconazole, epoxiconazole and flusilazole were applied to 12 different agricultural soils at background levels. Bioaccumulation to earthworm E. andrei and lettuce L. sativa roots and leaves was evaluated in non-aged (biota exposure after addition of pesticides) and aged (exposure started three months later) systems. In contrast with expectations from ageing effect (decrease of bioavailability), bioaccumulation in E. andrei was both reduced and enhanced after ageing depending on soil properties. The reduction of bioaccumulation correlated positively to the percentage of clay but negatively to soil organic matter. The affinity of compost worm E. andrei towards organic matter where hydrophobic pesticide molecules are sorbed is discussed as a possible explanation. An apparent effect of ageing (reduction of bioavailability) was particularly observed in lettuce roots, where bioaccumulation was significantly reduced in time. However, bioaccumulation in leaves changed ambiguously in aged variants among CFs, possibly as a combined result of bioconcentration, dilution by plant growth and metabolism. This study brings first insights into how the bioaccumulation of conazole fungicides is affected by sequestration in agricultural soils. The results indicate that in complex systems, the ageing is not necessarily connected with decrease of bioaccumulation.
- MeSH
- bioakumulace MeSH
- biologická dostupnost MeSH
- epoxidové sloučeniny MeSH
- fungicidy průmyslové analýza metabolismus MeSH
- jíl MeSH
- látky znečišťující půdu analýza metabolismus MeSH
- Oligochaeta metabolismus MeSH
- pesticidy analýza MeSH
- půda chemie MeSH
- salát (hlávkový) metabolismus MeSH
- silany MeSH
- triazoly MeSH
- zemědělství MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Due to the presence of toxic pollutants, soils in former military areas need remedial actions with environmentally friendly methods. Greenhouse experiments were conducted to investigate the aided phytostabilization of multi-heavy metals (HMs), i.e. Cd, Cr, Cu, Ni, Pb, Zn, in post-military soil by Festuca rubra and three mineral amendments (diatomite, dolomite and halloysite). The amendments were applied at 0 and 3.0% to each pot filled with 5 kg of polluted soil. After seven weeks of the phytostabilization, selected soil properties, biomass yield of F. rubra and immobilization of HMs by their accumulation in plant and redistribution among individual fractions in soil were determined. In addition, ecotoxicology parameters of non-amended and amended soil were established using Phytotoxkit (Sinapsis alba) and Ostracodtoxkit (Heterocypris incongruens) tests. The addition of halloysite significantly increased F. rubra biomass. Diatomite significantly increased both the Cd, Cu, Pb and Cr concentrations in the roots and the pH of the soil. The application of halloysite significantly decreased the Cd and Zn contents of the soil after the completion of the experiment. Dolomite and halloysite were more effective in HM immobilization in soil by decreasing their content in an exchangeable fraction than diatomite. These soil amendments significantly differentiated the length of S. alba roots and had a positive effect on the development of H. incongruens.
- MeSH
- biodegradace MeSH
- biomasa MeSH
- Festuca chemie růst a vývoj MeSH
- hořčík chemie MeSH
- jíl chemie MeSH
- kořeny rostlin růst a vývoj MeSH
- látky znečišťující půdu analýza MeSH
- půda chemie MeSH
- regenerace a remediace životního prostředí metody MeSH
- těžké kovy analýza MeSH
- uhličitan vápenatý chemie MeSH
- vojenská zařízení * MeSH
- Publikační typ
- časopisecké články MeSH
Conazole fungicides are currently used pesticides with considerable chronic toxicity and ecotoxicity that are also on EU list for substitution. They enter the soil forming short- or long-term residues. In this study two of their representatives, epoxiconazole (EPC) and tebuconazole (TBC), have been tested with 20 soils from the Czech Republic for their adsorption. Adsorption, by means of Kd coefficients, was compared to "basic" (TOC, pH, clay …) and "advanced" (surface area, minerals ..) soil properties. After doing multivariate analysis of the variables it was apparent that adsorption of both pesticides was highly associated with pH (negatively correlated), and less associated with soil organo-mineral complex (TOC, clay and surface area) and C and N in soil organic matter (OM). Particle sizes or cation exchange capacity (CEC) did not show correlation with adsorption, but showed an association in multidimensional space in factor analysis (FA). Some correlations were revealed between EPC adsorption and soil organic matter parameters. Recalculating Kd to Koc and to Gibb's free energy (ΔG) and its values indicated that the adsorption of EPC and TBC is mainly weak physical adsorption - partitioning. Also, ΔG values gave better correlation with pH(H2O) than Kd. Surface area impacted EPC adsorption. From the several soil minerals, kaolinite showed EPC and TBC adsorption. EPC adsorption was not highly influenced with pH changes compared to TBC. The number and types of H-bonds with molecular geometry govern the sorption, which might crucially affect leachibility in soil, and this may indicate that TBC is more leachable than EPC for the same soil.
- MeSH
- adsorpce MeSH
- epoxidové sloučeniny chemie MeSH
- jíl MeSH
- kationty MeSH
- látky znečišťující půdu chemie MeSH
- minerály chemie MeSH
- pesticidy chemie MeSH
- půda chemie MeSH
- triazoly chemie MeSH
- velikost částic MeSH
- zemědělství MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
Dating of clay bricks (adobe) and plasters is a relevant topic not only for building historians in the Pannonian region. Especially in vernacular architecture in this region, clay with straw amendments is a dominant construction material. The paper presents the potential of the molecular decay of these amendments to establish prediction tools for age based on infrared spectroscopic measurements. Preliminary results revealed spectral differences between the different plant parts, especially culms, nodes, and ear spindles. Based on these results, a first prediction model is presented including 14 historic samples. The coefficient of determination for the validation reached 62.2%, the (RMSE) root mean squared error amounted to 93 years. Taking the limited sample amount and the high material heterogeneity into account, this result can be seen as a promising output. Accordingly, sample size should be increased to a minimum of 100 objects and separate models for the different plant parts should be established.
- MeSH
- časové faktory MeSH
- jíl chemie MeSH
- konstrukční materiály analýza MeSH
- spektrální analýza MeSH
- stopové prvky analýza MeSH
- Publikační typ
- časopisecké články MeSH
The adhesive systems have the function to establish the connection between the restorative material and dental tissue, therefore it is of fundamental importance, because failures in the adhesive interface can reduce the life of a dental restoration. This study investigated the possibility of using the adhesive layer as a chlorhexidine modified release system evaluating their impact on the properties of these systems as well as evaluating the impact of these systems on immediate and post-aging dentin adhesion. Were used a matrix with BisGMA, UDMA, HEMA and TEGDMA copolymer and clay particles (Dellite 67G); associated with a chlorhexidine and a camphorquinone photoinitiator system. The properties of these systems were evaluated by the XRD, FTIR spectrophotometer, flexural strength, elasticity modulus, drug release, enzymatic inhibition and dentin adhesion resistance. The presence of the clay can raise the mechanical properties of the adhesive systems engendering a more resistant hybrid layer and led to a more sustained release of chlorhexidine in the systems, allowing a longer effective period of MMP-2 inhibition. The hypothesis that the addition of clays as release modulators could increase the effectiveness of these drugs in inhibiting the dentin's MPPs and consequently enhancing the adhesive durability was confirmed. These results indicate that the controlled release of chlorhexidine is able to reduce the process of loss of adhesion presenting itself as a promising system to increase the longevity of dental restorations.
- MeSH
- biokompatibilní materiály MeSH
- časové faktory MeSH
- chlorhexidin chemie MeSH
- dentin chemie MeSH
- dentinová adheziva MeSH
- jíl chemie MeSH
- léky s prodlouženým účinkem MeSH
- pevnost v tahu MeSH
- testování materiálů MeSH
- uvolňování léčiv * MeSH
- zubní materiály * MeSH
- Publikační typ
- časopisecké články MeSH
The elimination of egg stickiness is required for effective artificial reproduction of northern pike, but until now, available methods have required at least 40 min. Sodium hypochlorite was tested under laboratory conditions, and exposure to aqueous concentrations of 0.025-0.05% for 40 s effectively eliminated stickiness without adverse effects. Fertilization and hatching rates in laboratory trials were similar to those observed in eggs treated with traditional methods using clay or milk for 40 or 60 min, respectively, as well as those without treatment. Testing using conventional hatchery incubation techniques did not reveal differences in fertilization rates, while the number of hatched larva was significantly higher in eggs treated with sodium hypochlorite vs. clay. Eggs treated with sodium hypochlorite retained transparency, which facilitated monitoring of embryo development.
- MeSH
- buněčná adheze * MeSH
- chlornan sodný chemie MeSH
- dezinficiencia chemie MeSH
- Esocidae fyziologie MeSH
- fertilizace in vitro veterinární MeSH
- jíl chemie MeSH
- mléko chemie MeSH
- ovum cytologie fyziologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Nanofibrous elastic material based on the blend of hydrophobic poly(ε-caprolactone) (PCL) and hydrophilic gelatin (Gel) reinforced with halloysite nanotubes (HNTs) was prepared by electrospinning process by respecting principles of "green chemistry" required for tissue engineering and drug delivery carriers. Three different kinds of HNTs with similar aspect ratio, but different length and inner diameter were examined to explain the effect of HNT concentration and geometry on a structure, morphology, chemical composition, mechanical properties and biocompatibility of nanostructured materials. Reinforcing effect of each type of HNTs has been confirmed up to 6 wt%. However, the highest improvement of mechanical properties was exhibited by addition just 0.5 wt% of HNTs. All HNT modified nanofibers have been confirmed as non-cytotoxic based on the interaction with mouse fibroblasts NIH-3T3 cells and therefore suitable for biomedical applications, e.g. as wound healing coverings with controlled drug delivery.
- MeSH
- buňky NIH 3T3 MeSH
- fibroblasty cytologie MeSH
- hojení ran * MeSH
- hydrolýza MeSH
- jíl MeSH
- mechanický stres MeSH
- myši MeSH
- nanotrubičky chemie ultrastruktura MeSH
- nanovlákna chemie ultrastruktura MeSH
- polyestery chemie MeSH
- proliferace buněk MeSH
- pružnost * MeSH
- silikáty hliníku chemie MeSH
- skot MeSH
- spektrometrie rentgenová emisní MeSH
- spektroskopie infračervená s Fourierovou transformací MeSH
- viabilita buněk MeSH
- želatina chemie MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- skot MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Here we show that a commercial blocking reagent (G2) based on modified eukaryotic DNA significantly improved DNA extraction efficiency. We subjected G2 to an inter-laboratory testing, where DNA was extracted from the same clay subsoil using the same batch of kits. The inter-laboratory extraction campaign revealed large variation among the participating laboratories, but the reagent increased the number of PCR-amplified16S rRNA genes recovered from biomass naturally present in the soils by one log unit. An extensive sequencing approach demonstrated that the blocking reagent was free of contaminating DNA, and may therefore also be used in metagenomics studies that require direct sequencing.
- MeSH
- biomasa MeSH
- jíl MeSH
- kontaminace DNA MeSH
- laboratoře MeSH
- metagenomika MeSH
- polymerázová řetězová reakce MeSH
- půdní mikrobiologie MeSH
- reagenční diagnostické soupravy normy MeSH
- ribozomální DNA genetika izolace a purifikace MeSH
- RNA ribozomální 16S genetika izolace a purifikace MeSH
- sekvenční analýza DNA MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
