Impact of the cation symmetry on the mutual solubilities between water and imidazolium-based ionic liquids

Aiming at the evaluation of the impact of the ionic liquids (ILs) cation symmetry on their phase behaviour, in this work, novel mutual solubilities with water of the symmetric series of [C(n)C(n)im][NTf2] (with n=1-5) were determined and compared with their isomeric forms of the asymmetric [C(n)C(1)im][NTf2] group. While the solubility of isomeric ILs in water was found to be similar, the solubility of water in ILs follows the same trend up to a maximum cation alkyl side chain length. For n >= 4 in [C(n)C(n)im][NTf2] the solubility of water in the asymmetric ILs is slightly higher than that observed in the symmetric counterparts. The thermodynamic properties of solution and solvation derived from the experimental solubility data of ILs in water at infinite dilution, namely the Gibbs energy, enthalpy and entropy were used to evaluate the cation symmetry effect on the ILs solvation. It is shown that the solubility of ILs in water is entropically driven and highly influenced by the cation size. Accordingly, it was found that the ILs solubility in water of both symmetric and asymmetric series depends on their molecular volume. Based on these findings, a linear correlation between the logarithm of the solubility of ILs in water and their molar volume is here proposed for the [NTf2]-based ILs at a fixed temperature.

Effects of two teaching strategies on the relationship between nursing students’ self-efficacy and performance in BLS/AED

Purpose: Nurses and nursing students are often first responders to in-hospital cardiac arrest events; thus they are expected to perform Basic Life Support (BLS) and use an automated external defibrillator (AED) without delay. The aim of this study was to explore the relationship between nursing students’ self-efficacy and performance before and after receiving a particular training intervention in BLS/AED. Materials and methods: Explanatory correlational study. 177 nursing students received a 4-h training session in BLS/AED after being randomized to either a self-directed (SDG) or an instructor-directed teaching group (IDG).1 A validated self-efficacy scale, the Cardiff Test and Laerdal SkillReporter® software were used to assess students’ self-efficacy and performance in BLS/AED at pre-test, post-test and 3-month retention-test. Independent t-test analysis was performed to compare the differences between groups at pre-test. Pearson coefficient (r) was used to calculate the strength of the relationship between self-efficacy and performance in both groups at pre-test, post-test and retention-test. Results: Independent t-tests analysis showed that there were non-significant differences (p-values > 0.05) between groups for any of the variables measured. At pre-test, results showed that correlation between self-efficacy and performance was moderate for the IDG (r = 0.53; p < 0.05) and the SDG (r = 0.49; p < 0.05). At post-test, correlation between self-efficacy and performance was much higher for the SDG (r = 0.81; p < 0.05) than for the IDG (r = 0.32; p < 0.05), which in fact was weaker than at pre-test. Finally, it was found that whereas the correlation between self-efficacy and performance increased from the post-test to the retention-test to almost reach baseline levels for the ILG (r = 0.52; p < 0.05), it slightly decreased in this phase for the SDG (r = 0.77; p < 0.05). Conclusion: Student-directed strategies may be more effective than instructor-directed strategies at promoting self-assessment and, therefore, may help to improve and maintain the relationship between nursing student self-efficacy and actual ability to perform BLS/AED.