Aqueous solutions of three kinds of surface active ionic liquids composed of the 1-alkyl-3-methylimidazolium cation have been investigated by means of surface tension and electrical conductivity measurements at room temperature (298 K). The surface tension measurements provided a series of parameters, including critical micelle concentration (cmc), surface tension at the cmc (gammacmc), adsorption efficiency (pC20), and effectiveness of surface tension reduction (Picmc). In addition, with application of the Gibbs adsorption isotherm, maximum surface excess concentration (Gammamax) and minimum surface area/molecule (Amin) at the air-water interface were estimated. The effect of sodium halides, NaCl, NaBr, and NaI, on the surface activity was also investigated. It was found that both the pC20 and the Picmc were rather larger than those reported for traditional ionic surfactants and the cmc values were somewhat lower than those for typical cationic surfactants, alkyltrimethylammonium bromides, and comparable to typical anionic surfactants, sodium alkyl sulfates. These results demonstrate that the surface activity of long-chained imidazolium IL is somewhat superior to that of conventional ionic surfactants.

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Abstract:We argue that the decision to bribe bureaucrats depends on the frequency of corruption within a society. We provide a behavioral model to explain this conduct: engaging in corruption results in a disutility of guilt. This implies that people observe a lower probability to be involved in corruption if on average the guilt level of others within a country is higher. We also explore whether -and to what extent -group dynamics or socialization and past experiences affect corruption. In other words, we explore theoretically and empirically whether corruption is contagious and whether conditional cooperation matters. We use the notion of "conditional corruption" for these effects. The empirical section presents evidence using two data sets at the micro level and a large macro level international panel data set covering almost 20 years. The results indicate that the willingness to engage in corruption is influenced by the perceived activities of peers and other individuals. Moreover, the panel data set at the macro level indicates that the past level of corruption has a strong impact on the current corruption level.JEL classification: K420, D720, D640, O170, J240 Keywords: corruption, contagion effect, conditional cooperation, interdependent preferences * Corresponding author. E-mail addresses: benno.torgler@qut.edu.au, For helpful comments and suggestions thanks are due to Alison Macintyre and Susan Rose-Ackerman.