Manifestation of hydration of Na+ and Cl- ions in the IR spectra of NaCl aqueous solutions in the range of 2750-4000 cm-1

This work is aimed at the study at studying the influence of the interaction of solvate shells on the profiles of the IR spectra of sodium chloride solutions in the 2750-4000 cm^-1 range. The IR spectra of distilled water and sodium chloride solutions were obtained with the limit (0.356 g per 100 g of water) and 50 % of the limit (0.178 g per 100 g of water) concentrations at a temperature of 21˚. Theoretical methods based on the use of the DFT approach with the XLYP exchange-correlation potential are used to calculate the profiles of the IR spectra of clusters containing 9 water molecules per one NaCl molecule at the limit concentrations of the solution. In the case when the cluster contained a NaCl molecule, the spectra were calculated for interacting and non-interacting solvate shells in which the number of H₂O molecules varied from 3 to 6. The expansion of the experimental band profile on a basis containing the profiles of the theoretical bands made it possible to study the features of NaCl hydration with a change in the concentration of solutions. It was found that the IR spectrum band is formed mainly by interacting Na⁺ and Cl^- solvation shells, each containing 4 H₂O molecules, while the ninth H₂O molecule provides the bond between the solvated ions. As the salt concentration increases, the contribution of the solvation shells to the band profile increases too. The agreement reached in the positions and profiles of experimental and theoretical water bands at different solution concentrations substantiates the adequacy of the theoretical description of NaCl hydration. Theoretical studies explained the effect of a decrease in the band width, an increase in the peak intensity, and a shift of its maximum toward higher wavenumbers with increasing solution concentration.

Assessing the impact of public education on a preventable zoonotic disease: rabies

Effective methods to increase awareness of preventable infectious diseases are key components of successful control programmes. Rabies is an example of a disease with significant impact, where public awareness is variable. A recent awareness campaign in a rabies endemic region of Azerbaijan provided a unique opportunity to assess the efficacy of such campaigns. A cluster cross-sectional survey concerning rabies was undertaken following the awareness campaign in 600 households in 38 randomly selected towns, in districts covered by the campaign and matched control regions. This survey demonstrated that the relatively simple awareness campaign was effective at improving knowledge of rabies symptoms and vaccination schedules. Crucially, those in the awareness campaign group were also 1·4 times more likely to report that they had vaccinated their pets, an essential component of human rabies prevention. In addition, low knowledge of appropriate post-exposure treatment and animal sources of rabies provide information useful for future public awareness campaigns in the region and other similar areas.