Combinations Of Binary Mixtures Research Articles

Evaluation of the bioluminescence activity, biokinetics, and the effects of binary mixtures of inducers on the Pm-lux recombinant strain

The bioluminescence activity and biokinetics of a recombinant Pseudomonas putida mt-2 were investigated in the presence of various inducers: three chlorotoluenes (CTs) and two nitrotoluenes (NTs). The effects of binary mixtures (40 combinations) of eleven inducers on the bioluminescence activity were also studied. Different responses and toxicities were observed depending on the type of inducers and concentrations. The intensity of the bioluminescent response at 1 mM of individual inducers was in the following order: o-CT > p-CT > m-CT > o-NT and p-NT. The biokinetics calculated based on the bioluminescence activity was in the range of 0.109–8.417 mM for the half-saturation constant (Ks) and 6.083–19.880 h−1 for the maximum SBR (µmax). In the case of binary mixtures, the observed bioluminescence was 4–810% (avg. 80.4%) of the expected bioluminescence intensity depending on the combinations (0.0001 < p < 0.5226). Among these binary mixture combinations, 27 out of 40 combinations indicated antagonistic effects (3–83% of expected activity; p < 0.0391) under the exposure of inducer mixtures. Overall, this study demonstrated that the proper biomonitoring for specific chemicals could be established by considering the characteristics of mixture pollutants for their possible usages as a preliminary rapid and field analytical bio-tool.

Experimental study and DEM analysis of granular segregation in a rotating drum

In this work, we experimentally and numerically investigated the mixing/segregation behavior of particles in an unbaffled rotary drum. We analyzed different combinations of binary mixtures that varied in density and size. We also quantified the effect of filling degree and rotational speed of the drum on the mixing index of each binary mixture. We used the discrete element method (DEM) for the simulation study, in which we determined the input parameters by both experimental measurements and calibration. The results reveal that the simulations using experimentally measured DEM input parameters had the best agreement with the experimental responses (repose angle and radial mixture). The experimental and simulation results enabled us to analyze the significant effects of filling degree and rotational speed on the granular radial and axial segregation of different binary mixtures.

Kinetic and thermodynamic studies of sorption of lead and cadmium from aqueous solution by <i>Moringa oleifera</i> pod wastes

Equilibrium sorption of Pb(II) and Cd(II) from aqueous solution by Moringa oleifera pods waste was conducted under batch conditions. Effects of operating variables such as initial concentration, contact time, adsorbent dose, pH and temperature on the sorption of these heavy metals have been studied. The optimum pH for the adsorption was found to be 5.0 and the adsorption process was found to be exothermic for both metal ions. The competitive adsorption characteristics of the combinations of binary mixtures of aqueous metal ion species, Pb2+ (aq) and Cd2+ (aq), on the adsorbent were also investigated. The Langmuir, Freundlich, Temkin and Dubinin Radushkevich adsorption isotherm models were used to analyse the equilibrium data. Kinetics data evaluation showed that the adsorption followed a pseudo-second order model. A solution of 0.05 M HCl has been found to be sufficient for the regeneration of spent adsorbent with up to 90% recovery for the two metal ions.

Assessing combined impacts of agrochemicals: Aquatic macroinvertebrate population responses in outdoor mesocosms

Agricultural ditches host a diverse community of species. These species often are unwarrantedly exposed to fertilizers and a wide-array of pesticides (hereafter: agrochemicals). Standardized ecotoxicological research provides valuable information to predict whether these pesticides possibly pose a threat to the organisms living within these ditches, in particular macro-invertebrates. However, knowledge on how mixtures of these agrochemicals affect macro-invertebrates under realistic abiotic conditions and with population and community complexity is mostly lacking. Therefore we examined here, using a full factorial design, the population responses of macroinvertebrate species assemblages exposed to environmentally relevant concentrations of three commonly used agrochemicals (for 35days) in an outdoor experiment. The agrochemicals selected were an insecticide (imidacloprid), herbicide (terbuthylazine) and nutrients (NPK), all having a widespread usage and often detected together in watersheds. Effects on species abundance and body length caused by binary mixture combinations could be described from single substance exposure. However, when agrochemicals were applied as tertiary mixtures, as they are commonly found in agricultural waters, species' abundance often deviated from expectations made based on the three single treatments. This indicates that pesticide-mixture induced toxicity to population relevant endpoints are difficult to extrapolate to field conditions. As in agricultural ditches often a multitude (approx. up to 7) of agrochemicals residues are detected, we call other scientist to verify the ecological complexity of non-additive induced shifts in natural aquatic invertebrate populations and aquatic species assemblages.

Genotoxic evaluation of different δ-endotoxins from Bacillus thuringiensis on zebrafish adults and development in early life stages

The use of toxins from Bacillus thuringiensis as biopesticides in the biological control of insects and in transgenic plants has increased their availability in the environment. Ecotoxicological evaluations of four δ-endotoxins cry 1Aa, cry 1Ab, cry 1Ac, and cry 2A from B. thuringiensis were carried out on zebrafish Danio rerio to explore the adverse effects on their genome and embryos. Cry 1Aa increased the micronucleus (MN) frequency in peripheral erythrocytes of adult D. rerio, while cry 1Ab, cry 1Ac and cry 2A did not show genotoxicity, after 96-h of exposure at concentration of 100 mg/L. Exposures to binary mixtures (cry 1Aa + cry 1Ac, 50:50 mg/L) and (cry 1 Aa + cry 2A, 50:50 mg/L) for 96-h showed also significant increased MN frequency. Other evaluated binary mixtures did not show genotoxicity. Activity of glutathione S-transferase measured in the gills did not seem to be altered after exposure to all tested toxins as well as to the six combinations of binary mixtures. In the embryo-larval study, all tested δ-endotoxins showed embryo toxicity and developmental delay after exposure to the concentrations of 25, 50, 100 and 150 mg/L for 96-h. However, each toxin presented a different pattern of toxic response suggesting that a specific approach should be taken into account to its toxicological evaluations.

Biosensor for Seven Sulphonamides in Drinking, Ground, and Surface Water with Difficult Matrices

Environmental monitoring of antibiotics and other pharmaceuticals in real water samples with difficult matrices places high demands on chemical analysis. Biosensors have suitable characteristics like their efficiency in a fast, sensitive, and cost‐effective detection of pollutants. In this article, we present a recently developed immunoassay for seven sulphonamides (sulphadiazine, sulphamethoxazole, sulphadimidine, sulphamethizole, sulphadimethoxine, sulphathiazole, and sulphamethoxypyridazine) which can only be detected separately. For the simultaneous determination of multiple sulphonamides in the future we performed measurements with different combinations of binary mixtures. The results of the immunosensor were compared to a mathematical model which was developed in our group. Using an automated biosensor system it was possible for the first time to achieve limits of detection (LOD) below 10 ng L−1 and limits of quantification (LOQ) below 100 ng L−1 without sample pre‐concentration for these sulphonamides. Sulphonamide calibrations with different immobilised analyte derivatives were made in Milli‐Q water. Unstrained spiked and un‐spiked real water samples with complex matrices (drinking, ground, and surface water) were measured. In compliance with the Association of Analytical Communities (AOAC) International most recovery rates obtained were between 70% and 120%. The reproducibility was checked by measuring replica of each sample within independent repetitions. Robustness could be demonstrated by long‐term stability tests of the biosensor surface. These studies show that the biosensor used offers the necessary reproducibility, precision, and robustness required for an analytical method. The measuring data of the binary mixtures show a systematic error compared to the mathematical model at high concentrations of both sulphonamides, because the approximation uses only the standard calibration curves (data of the logistic fit function) as input data. It is also hard to adequately describe the cross‐reactivity and the behaviour of a mixture of polyclonal antibodies.

The yield and competitive ability of euploid and aneuploid genotypes of tetraploid Lolium perenne in two seasons at two locations

Six genotypes derived from a high and low yielding selection within each of the 3 chromosome classes 27, 28 (euploid) and 29 were grown as pure stands and in all possible binary mixture combinations in a tray experiment carried out at Aberystwyth and Newcastle over a two year period. Dry matter yield, tiller number and plant height were recorded for each of several harvests each season. The results showed that: 1) (i) the euploids were of high yield and average competitive ability, (ii) the hypoploids were of average yield and low competitive ability, (iii) the hyperploids were of lower than average yield and of high competitive ability; 2) Insome cases significant differences were found between selections within a chromosome class; 3) Mixture performance was intermediate to that of the component pure stands; 4) When high yielding selections were grown in a mixture with a selection of superior competitive ability they tended to produce more tillers per unit dry weight than in pure stands. It was concluded that, until more is known of the relative performance of euploids and aneuploids, marketed seed should contain as high a proportion of euploids as possible.