Sorption measurements of autoclaved aerated concretes diffusion coefficient

This study presents the results of sorption measurements and analyzes their applicability in the determination of the moisture diffusion coefficient in the porous media in which these processes occur. The test involved three classes of autoclaved aerated concrete density: 500, 600 and 700. The sorption processes under examination covered practically the whole range of hygroscopic humidity from RH = 0% up to RH = 98%. The idea of the experiment was to place dry samples of the tested concretes to 98% relative humidity stimulated by the saturated water solution of K2SO4. The tests were performed until weight stabilization of all samples, which took about 10 months. On the basis of the results obtained, individual diffusion coefficients were determined using two different calculation procedures: the square root of time method and the logarithmic method. The first method applies to the initial stage of the process, while the other is used at its advanced stage. Both measurement methods were assessed in terms of their applicability and compatibility.

Research on Expanded Graphite/Nitrate High-Temperature Composite Phase Change Materials

In order to enhance the thermal conductivity of high-temperature phase change materials (PCMs), expanded graphite (EG) /NaNO3-LiNO3 composite was prepared by the method of eutectic aqueous solution infiltration porous structure of EG. The composites with an EG amount of 10%, 20% and 30% were prepared in the similar way. The results proved that the eutectic was an excellent PCM, for its melting (solidification) temperature was 193.7 (191.7) °C, and its latent heat was 272.6(262.6) kJ/kg. With the increasing in graphite amount, the thermal conductivity of the composite was found to progressively increase with intensifications up to 10. We can conclude that the saturated water solution method was a simple and effective way to strengthen the thermal conductivity of the eutectic.

Follow-up study of prevalence and control of ascariasis in swine populations in Serbia

The cause of the most significant helminth diseases in swine — Ascaris suum, can also causes infections in humans. The use of swine manure in agriculture renders the eggs of this ascaridida an accessible source of infection, thus posing a significant risk factor for human health. With the objective of proving the prevalence of infection with A. suum nematodes in the territory of Serbia, investigations were carried out in the period between 2007–2011 in the territories of five districts: North Bačka, South Banat, Braničevo, Zlatibor and Nišava. The investigations covered coprological examinations of 1031 feces samples of swine originating from farms owned by individual breeders. The samples were examined using the standard flotation method with a saturated water solution of NaCl. The established prevalence of ascariasis infection amounted to 47.62% (1031/491). The biggest prevalence of infection was determined in the territory of the Braničevo District, 65.78% (301/198), and the smallest in the territory of the Nišava District, 32.24% (183/59). In spite of its prevalence and vast economic importance, there is still insufficient information about the key aspects of the biology and epidemiology of A. suum. Viewed from the aspect of epizootiology, it is very important to know the prevalence of swine infections with Ascaris because of the possible infection of humans by its migrating larvae.

Characterization of β-Cyclodextrin-Thymol Inclusion Complexes

Thymol had been confirmed to be applied to prevent the growth of bacteria and function as an antioxidant to maintain the quality of food products. It is known that a number of components of essential oils including thymol are suitable to form inclusion complexes with β-Cyclodextrin, since they fit the hydrophobic cavity tightly. The β-cyclodextrin-thymol(β-CD-thymol) inclusion complexes were prepared by the saturated water solution method. SEM results showed that the lattice of β-CD-thymol inclusions was different from hydrogen-bond-type crystal lattice of β-CD and β-CD-water inclusions; the disappearance of high-energy water molecules in the β-CD cavity was observed from SAT data; the aromatic ring of the thymol was included in the β-CD cavity, according to the FTIR data. Besides, according to the calculation of chemical structure, molecular size of thymol was estimated. These results supported a successful formation of the inclusion and the preliminary structure of host-guest inclusions was constructed, indicating the -CH3 is close to the β-CD narrower rim, while the -CH2 and OH group is close to the wide one.

The effect of β-cyclodextrin and pH on bifonazole hydrosolubility

The equlibria of bifonazole in saturated water solution within the pH range 4 to 10 [I = 0.1 mol/dm3 (NaCl); 25 ?C] were studied spectrophotometrically. Based on the equlibrium constants determined in a heterogeneous system, the acidity constant (pKa = 5.72) and solubility in water (S=10-5.79+10-(pH + 0.07))were calculated. The influence of ?-cyclodextrin on bifonazole solubility was examined in the presence of 10-3 and 10-4 mol/dm3 ?-cyclodextrin. At pH values over 8, bifonazole solubility was two- and 13-fold increased in the presence of 10-4 and 10-3 mol/dm3 ?-cyclodextrin respectively, compared to its solubility in water. The ratio of bifonazole solubility in the presence of ?-cyclodextrin and that in water decreased in parallel to the increase of acidity.