University of Zagreb

About: University of Zagreb is a education organization based out in Zagreb, Grad Zagreb, Croatia. It is known for research contribution in the topics: Population & European union. The organization has 21769 authors who have published 50267 publications receiving 783239 citations. The organization is also known as: Zagreb University & Sveučilište u Zagrebu.

Trends in oxygen content 1911–1984 and occurrence of benthic mortality in the northern Adriatic Sea

Abstract: Trends of dissolved oxygen content of the surface and bottom layers of the northern Adriatic Sea are analysed for the period 1911–1984. An increase in the surface layer and a decrease in the bottom layer are observed in all seasons except winter. Although the oxygen content of the water column as a whole has not changed significantly, it is inferred, from the increasing difference between the surface and the bottom layer, that the primary productivity of the northern Adriatic Sea is increasing. As the average midsummer oxygen content of the bottom layer decreases, the frequency of mass mortality in the benthic fauna is expected to increase, especially in the northern and western subareas.

Importance of S-layer proteins in probiotic activity of Lactobacillus acidophilus M92

Abstract: J. FRECE, B. KOS, I.K. SVETEC, Z. ZGAGA, V. MRSAA ND J. SUSKOVIC´ . 2004. Aims: To investigate the functional role of surface layer proteins (S-layer) in probiotic strain Lactobacillus acidophilus M92, especially its influence on adhesiveness to mouse ileal epithelial cells. Methods and Results: Sodium dodecyl sulphate polyacrylamide gel electrophoresis of cell surface proteins revealed the presence of potential surface layer (S-layer) proteins, ca at 45 kDa in L. acidophilus M92. Southern blot with pBK1 plasmid, containing slpA gene, gave a positive signal, suggesting that L. acidophilus M92 has a slpA gene coding for the S-layer proteins. S-layer proteins of this strain are present during all phases of growth. The S-layer proteins appeared when cells treated with 5 mol l )1 LiCl were allowed to grow again. Removal of the S-layer proteins reduced adhesion of L. acidophilus M92 to mouse ileal epithelial cells. Furthermore, the viability of cells without S-layer were reduced in simulated gastric juice at low pH range (2, 2AE5, 3) and simulated pancreatic juice with bile salts (1AE 5a nd 3gl )1 ). S-layer proteins of L. acidophilus M92 were resistant to pepsin and pancreatin, in contrast, the treatment with proteinase K led to a significant proteolysis of the S-layer proteins. Conclusions: These results demonstrated functional role of S-layer; it is responsible for adhesiveness of Lactobacillus acidophilus M92 to mouse ileal epithelial cells and has a protective role for this strain. Significance and Impact of the Study: S-layer proteins have an important role in the establishment of probiotic strain Lactobacillus acidophilus M92 in the gastrointestinal tract.

Thermophysical Comparison of Five Commercial Paraffin Waxes as Latent Heat Storage Materials

Abstract: Thermophysical properties of phase change materials (PCM) are of utmost importance in latent heat thermal energy storage (LHTES) applications. Therefore, an experimental study is conducted in order to determine thermophysical properties of five technical grade paraffin waxes produced by major Croatian oil company, INA d.d. Rijeka. The temperatures and enthalpies of melting and solidification (latent heat capacity) and specific heat capacities of solid and liquid paraffin waxes were measured by differential scanning calorimetry (DSC). The thermal diffusivity of paraffin waxes was determined utilizing transient method. The importance of eliminating phase transformation interferences to thermophysical properties determination is addressed. The densities and the coefficient of thermal expansion were measured using Archimedes methods. A self-adopted simple and inexpensive laboratory procedure for the determination of liquid density as a temperature function is presented. Finally, the thermal conductivities have been calculated from measured densities, heat capacities and diffusivities. Based on results obtained, the investigated paraffin waxes were evaluated in regard to their applicability as PCM for LHTES.