Interactions in mixed cationic surfactants and dextran sulfate aqueous solutions.

The interactions between a hydrophilic anionic polysaccharide, dextran sulfate, and oppositely charged surfactants, n-alkylammonium chlorides (the number of carbon atoms per chain being 10, 12, and 14), were investigated by optical microscopy, X-ray diffraction, microelectrophoretic mobility, conductivity, surface tension, and light-scattering measurements at 303 K. The increase of surfactant alkyl chain length shifts both the critical aggregation (cac) and the critical micelle concentrations (cmc) toward lower surfactant concentration. Light-scattering and microelectrophoretic data revealed the coexistence of differently structured complexes beyond the cac. The presence of giant vesicles indicates that at least one type of species is ordered in bilayers. X-ray analysis of dry n-alkylammonium dextran sulfates exhibited mesomorphous ordering and interplanar spacings typical for lamellar structures; i.e., n-alkylammonium molecules form more or less disordered bilayers interconnected with dextran sulfate chains, thus forming multilamellar stacks. The average basic lamellar thickness increased linearly with the increase of surfactant chain length, whereas the average number of lamellar bilayers in the stack of lamellae decreases.

[Caloric and nutritive value of kindergarten meals in Zagreb from 1988 to 1993]. / Energetska i prehrambena vrijednost obroka u djecjim vrticima grada Zagreba u razdoblju od 1988. do 1993. godine.

In the 1988-1993 period the mean energy value of meals in 24 Zagreb kindergartens was 4,161.63 kJ or 110.46 of the recommended standard (3,768 kJ). In the same time, the mean protein value 39.53 g/day amounted to 117.13% of the recommended amount of 33.75 g/day. The mean fat value was 139.04% of the recommended amount of fat (32.25 g) or 44.84 g/day. The mean amount of carbohydrate was 107.97 g/day, which was 95.97% of the standard (112.50 g/day). In the 1988-1990 period, the mean energy value of meals was 4,242 kJ or 112.66% of the recommended standard. In the same period, the mean protein value of 39.87 g/day amounted to 118.13% of the recommended. The mean fat value was 128.70% of the recommended amount of fat (32.25 g) or 45.37 g/day. The mean amount of carbohydrate was 111.75 g/day, which was 99.33% of the recommended values. In the 1991-1993 period, the mean energy value of meals was 4,102 kJ or 108.88% of the standard. With a mean amount of the 39.10 g/day, protein was represented by 115.85% of the standard. The mean amounts of fat and carbohydrate also considerably increased to 44.39 and 106.13 g/day or 125.92% and 94.33% of the standard, respectively. In 10 (41.6%) kindergartens (240 meals in total) normal value et least one out of the four parameters measured was not obtained throughout the period of observation.