Evaluation of the impact of soil contamination with mercury and application of soil amendments on the yield and chemical composition of Avena sativa L.

The purpose of this study was to determine the effect of soil contamination with Hg on the yield and chemical composition of Avena sativa L. Mercury was incorporated into soil in amounts: 0, 50, 100 and 150 mg Hg·kg-1of soil. Zeolite, lime and bentonite were used to alleviate the soil contamination. Plants cultivated in Hg-polluted soil showed growth inhibition even in the presence of bentonite, lime or zeolite. Under elevated doses of Hg, the yield of aerial mass and roots decreased. The soil amendments mitigated the adverse effect of contamination, with lime and bentonite having a more beneficial influence on the yield than zeolite. The incremental contamination with mercury led to an increase in the content of Hg in the biomass of the plants. A much higher content of Hg was found in roots than in aerial parts. The inactivating substances applied to soil to some extent limited the increase in the content of this metal in all plant organs. Lime proved to be most effective in this regard. An increase in the soil contamination with mercury caused an increased content of nitrogen and potassium in plant organs and a decrease content of phosphorus.

Interoperability Between Mobile Money Agents and Choice of Network Operators: The Case of Tanzania.

In this paper, we investigate the effects of non-exclusive agreements between networks of mobile money agents on mobile network operator choices, using survey data from Tanzania conducted in 2017. By combining survey responses with geo-location data and information on agent proximity, we employ discrete choice models to analyze consumers' decisions in subscribing to mobile network operators and their corresponding mobile money providers. Our findings highlight the significant influence of the distance to mobile money agents on consumers' subscription choices. To explore the impact of interoperability (non-exclusivity) at the mobile money agent level, where consumers can use the nearest agent from any mobile money provider, we assess its effects on market shares of mobile network operators. Our results indicate that interoperability at the agent level has only a minor impact on market shares. Smaller operators experience marginal gains as their consumers can now utilize agents of larger providers, which are often closer in proximity. In conclusion, we find that interoperability at the agent level does not considerably alter the market structure in the context Tanzania during the period under consideration.

Glycerolysis of Poly(lactic acid) as a Way to Extend the "Life Cycle" of This Material.

The article concerns the use of glycerolysis reaction as an alternative method of processing post-production and post-consumer waste from poly(lactic acid) (PLA). Management of waste is a very important issue from an environmental protection and economic point of view. Extending the "life cycle" of PLA is extremely important because it allows to make the most of this material. It also limits economic losses resulting from its disposal in the biodegradation process at the same time. This paper presents a method of glycerolysis of poly(lactic acid) waste using various amounts of anhydrous glycerol (mass ratio from 0.3 to 0.5 parts by weight of glycerol per 1.0 part by weight of PLA). This process was also carried out for pure, unmodified PLA Ingeo® (from NatureWorks) to compare the obtained results. The six liquid oligomeric polyhydric alcohols were obtained as a result of the synthesis. Then, they were subjected to physicochemical tests such as determination of color, smell, density, viscosity, and pH. In addition, the obtained raw materials were subjected to analytical tests such as determination of the hydroxyl value, acid value, water content, and elemental composition. The average molecular weights and dispersity were also tested by gel permeation chromatography (GPC). The assumed chemical structure of the obtained compounds was confirmed by spectroscopic methods such as FTIR, 1H NMR, 13C NMR. Glycerolysis products were also subjected to differential scanning calorimetry (DSC) to determine thermal parameters. The obtained research results have allowed the precise characterization of newly obtained products and determination of their suitability, e.g., for the synthesis of polyurethane (PUR) materials.