Solubility of gases in fluoroorganic alcohols. Part III. Solubilities of several non-polar gases in water¿+¿1, 1, 1, 3, 3, 3-hexafluoropropan-2-ol at 298.15¿K and 101.33¿kPa

Solubilities of the non-polar gases H2, N2, O2, CH4, C2H6, C2H4, CF4, SF6, and CO2 in the mixture (water + 1, 1, 1, 3, 3, 3-hexafluoropropan-2-ol) at the temperature of 298.15 K and 101.33 kPa partial pressure of gas are reported. A polynomial dependence of the solubilities on the molar fraction of the binary liquid mixture is found. The Henry''s constants at the vapor pressure of water, the standard changes in the Gibbs energy for the solution process and for the solvation process, and the so-called excess Henry''s constant are calculated. The results have been compared with those obtained by Scaled Particle Theory (SPT). A method to compare the solubility of a gas in different liquids is proposed and applied to 2, 2, 2-trifluoroethanol and 1, 1, 1, 3, 3, 3-hexafluoropropan-2-ol

Thermophysical and volumetric study of mixtures {p-cymene¿+¿propan-1-ol} at several temperatures and atmospheric pressure. Modeling with COSMO-RS

Experimental isobaric molar heat capacities at atmospheric pressure have been determined for the mixture {p-cymene + propan-1-ol} every 10 K in the temperature interval (298.8–328.5) K and over the entire composition range with a Calvet type calorimeter. Densities, necessary for calculating heat capacities, have been also measured in similar conditions. Excess molar volumes have been calculated from densities. They are positive at (318.15 and 328.15) K and sigmoidal at (298.15 and 308.15) K with negative values in the zone very rich in propan-1-ol. Excess molar heat capacities have been calculated from the molar heat capacities and show positive values. Both excess molar properties increase as the temperature rises at a given molar fraction. Excess properties are discussed in terms of intermolecular interactions. The solvation model COSMO-RS has been applied to predict the excess molar heat capacities, being the quantitative predictions rather poor

Solubilities of gases in cycloethers. The solubility of 13 nonpolar gases in 2, 5-dimethyltetrahydrofuran at 273.15 to 303.15¿K and 101.32¿kPa

The solubilities of gases in liquids are interesting, not only from a practical point of view, but also because they provide a rigorous touchstone to test the structural models on the liquid state. In this work the solubilities of 13 nonpolar gases, He, Ne, Ar, Kr, Xe, H2, D2, N2, CH4, C2H4, C2H6, CF4, and SF6, in 2, 5-dimethyltetrahydrofuran at five temperatures between (273.15 and 303.15) K and 101.32 kPa partial pressure of gas were measured and the associated thermodynamic functions were calculated. Correlation of data has been made and the capacity of prediction of several typical molecular models of liquids, namely, SPT model, perturbation theory, UNIFAC and COSMO-RS, specifically applied to gas solubilities, has been checked

Effects of the insecticide fipronil in freshwater model organisms and microbial and periphyton communities

Fipronil is a broad-spectrum insecticide whose release in the environment damages many non-target organisms. This study evaluated the toxicity of fipronil at two biological levels using in vivo conditions and environmentally relevant concentrations: the first based on two model organisms (aquatic invertebrate Daphnia magna and the unicellular freshwater alga Chlamydomonas reinhardtii) and a second based on three natural communities (river periphyton and freshwater and soil microbial communities). The physicochemical properties of fipronil make it apparently unstable in the environment, so its behaviour was followed with high performance liquid chromatography (HPLC) under the different test conditions. The most sensitive organism to fipronil was D. magna, with median lethal dose (LC50) values from 0.07 to 0.38 mg/L (immobilisation test). Toxicity was not affected by the media used (MOPS or river water), but it increased with temperature. Fipronil produced effects on the photosynthetic activity of C. reinhardtii at 20 °C in MOPS (EC50 = 2.44 mg/L). The freshwater periphyton presented higher sensitivity to fipronil (photosynthetic yield EC50 of 0.74 mg/L) in MOPS and there was a time-dependent effect (toxicity increased with time). Toxicity was less evident when periphyton and C. reinhardtii tests were performed in river water, where the solubility of fipronil is poor. Finally, the assessment of the metabolic profiles using Biolog EcoPlates showed that bacteria communities were minimally affected by fipronil. The genetic identification of these communities based on 16S rRNA gene sequencing revealed that many of the taxa are specialists in degrading high molecular weight compounds, including pesticides. This work allows us to better understand the impact of fipronil on the environment at different levels of the food chain and in different environmental conditions, a necessary point given its presence in the environment and the complex behaviour of this compound

Impact of citronellol on river and soil environments using non-target model organisms and natural populations

Citronellol is an acyclic monoterpenoid with a wide range of pharmacological activities (antibacterial, antifungal, anti-lice, repellent, lipolytic, anti-allergic, anti-inflammatory, antispasmodic, antidiabetic, anti-cholesterol, among other) and potential to replace synthetic products. However, the impact of citronellol on the environment remains unknown. We analysed, for the first time, the environmental impact of citronellol on river and soil environments using non-target model organisms and natural populations. The acute toxicity of citronellol on the aquatic invertebrate Daphnia magna, the plant Allium cepa L and the earthworm Eisenia fetida was quantified. The effect of citronellol in a river ecosystem was analysed using river periphyton communities taxonomically characterised and a river microbial community characterised through 16 S rRNA gene sequencing. Finally, a microbial community from natural soil was used to monitor the effect of citronellol on the soil ecosystem. The results showed that E. fetida was most sensitive to citronellol (LC50 = 12.34 mg/L), followed by D. magna (LC50 = 14.11 mg/L). Citronellol affected the photosynthesis of the fluvial periphyton (LC50 = 94.10 mg/L) and was phytotoxic for A. cepa. Furthermore, citronellol modified the growth and metabolism of both fluvial (LC50 = 0.19% v/v) and edaphic (LC50 = 5.07% v/v) bacterial populations. The metabolism of the microorganisms in the soil and water exposed to citronellol decreased with respect to the control, especially their ability to metabolise carbohydrates. Our results show that citronellol has a negative impact on the environment. Although acute effects cannot be expected, it is necessary to quantify the environmental levels as well as the long-term and persistent effects of this monoterpene

Molar heat capacities of the mixture {1, 8-cineole + ethanol} at several temperatures and atmospheric pressure

Molar heat capacities at atmospheric pressure have been determined every 5 K for the mixture {1, 8-cineole (1) + ethanol (2)} in the temperature interval (304.7 to 324.5) K and the whole composition range with a Calvet type calorimeter Setaram C80. From the molar heat capacities, excess molar heat capacities have been calculated, their values being positive and increasing as the temperature rises. The solvation model COSMO-RS has been applied to predict the excess molar heat capacities. The model overestimates the values of the excess heat capacities but predicts well the trend of variation of the excess molar heat capacity with the temperature

Ecotoxicity of a novel biopesticide from Artemisia absinthium on non-target aquatic organisms

Biopesticides are increasingly being used to replace synthetic pesticides for pest control. This change raises concern for its environmental impacts, especially on non-target organisms. In this study, the ecotoxicological effects of a potential nematicide from Spanish populations of Artemisia absinthium (var. Candial) were evaluated on freshwater and aquatic non-target organisms. The study focused on the aqueous extract (hydrolate), the principal component of which ((-) -(Z) -2, 6-dimethylocta-5, 7-diene-2, 3-diol) is responsible for its nematicidal effect. Until now, the hydrolate has been considered a byproduct of the process used to obtain essential oils, and there are no studies on its ecotoxicity from any plant with biopesticide properties. Our results indicated that A. absinthium hydrolate caused acute toxicity for non-target organisms at dilutions as low as 0.2%. The sensitivity of the organisms, from the most to the least sensitive, was: Daphnia magna (LC50 = 0, 236%) > Vibrio fisheri (LC50 = 1, 85%) > Chlamydomonas reinhardtii (LC50 = 16, 49). Moreover, the A. absinthium organic extract was highly toxic to D. magna (LC50 = 0, 093 mg/L). A. absinthium hydrolate toxicity was also tested on a natural river microbial community. Bacterial growth was not affected; the physiology of the community was only slightly modified, namely through an increased ability to degrade different substrates, mainly carbohydrates. This study provides for the first time an exhaustive assessment of the environmental exposure of a plant-derived biopesticide and shows that these products may cause a broad range of toxicity on non-target aquatic organisms

Brucellosis in Sub-Saharan Africa:Current challenges for management, diagnosis and control

Brucellosis is a highly contagious zoonosis caused by bacteria of the genus Brucella and affecting domestic and wild mammals. In this paper, the bacteriological and serological evidence of brucellosis in Sub-Saharan Africa (SSA) and its epidemiological characteristics are discussed. The tools available for the diagnosis and treatment of human brucellosis and for the diagnosis and control of animal brucellosis and their applicability in the context of SSA are presented and gaps identified. These gaps concern mostly the need for simpler and more affordable antimicrobial treatments against human brucellosis, the development of a B. melitensis vaccine that could circumvent the drawbacks of the currently available Rev 1 vaccine, and the investigation of serological diagnostic tests for camel brucellosis and wildlife. Strategies for the implementation of animal vaccination are also discussed.Publishe