Nutritional and therapeutic value of fermented caprine milk

Caprine milk is a nutritional and therapeutic food. The unique and beneficial characteristics of caprine milk that are superior to bovine milk include: better digestibility; greater buffering capacity; fat globules that are smaller in diameter and better distributed in the milk emulsion; higher content of short‐chain fatty acids in the milk fat; higher content of zinc, iron and magnesium; stronger lactoperoxidase (antimicrobial) system as well as better immunological and antibacterial characteristics. The larger amounts of some minerals, such as calcium, zinc and magnesium, in caprine milk may influence the growth of lactic acid bacteria since they are a normal part of some enzymatic complexes involved in lactose fermentation. The higher whey protein content could also be significant because Lactobacillus acidophilus and bifidobacteria grow better in the presence of higher levels of some amino acids (valine, glycine, hystidine). The use of caprine and ovine milk in cheesemaking is well known, but the production of fermented caprine milk via probiotics has not yet been developed, although many studies have highlighted the requirements for production of that kind of healthy food. During fermentation caprine milk loses its characteristic ‘goaty’ taste, which is unacceptable to many consumers. Moreover, the nutritive value of caprine milk increases during fermentation. The rise in the number of goat farms in Croatia has created the need to find other products that can be produced using caprine milk. According to the present situation in Croatia, there is no real possibility of producing fermented caprine milk for the global market, but many studies of fermented caprine milk have been performed.     

Green Synthesis of Acetals/Ketals: Efficient Solvent-Free Process for the Carbonyl/Hydroxyl Group Protection Catalyzed by SBA-15 Materials

Acetals/ketals derived from the aldehydes/ketones are easily prepared under solventless conditions. The process is heterogeneously catalysed using acid or basic mesoporous molecular sieves Al-SBA-15 and (Cs)Al-SBA-15. The catalytic procedure herein reported is applied to the preparation of the key intermediates for the synthesis of {3-[(2R,3R,4R,5R)-(2,3,4,5-tetrahydroxyhexane-1,6-diyl)]}di-1H-imidazole 2 with potential biomedical applications.     

Influence of depth of intermediate layer on optical power distribution in W-type optical fibers

For different depth and width of the intermediate layer, a power flow equation is used to calculate spatial transients and steady state of power distribution in W-type optical fibers (doubly clad fibers with three layers). A numerical solution has been obtained by the explicit finite difference method. Results show how the power distribution in W-type optical fibers varies with the depth of the intermediate layer for different values of intermediate layer width and coupling strength. We have found that with increasing depth of the intermediate layer, the fiber length at which the steady-state distribution is achieved increases. Such characterization of these fibers is consistent with their manifested effectiveness in reducing modal dispersion and improving bandwidth.     

Synthesis and characterization of hafnium carbide fine powders

Hafnium carbide powder was synthesized by sol–gel polycondensation of hafnium chloride with citric acid. The starting materials were dissolved in water and mixed homogeneously on a hot plate until precursor gel was formed. Pyrolysis of this gel resulted in monoclinic hafnia which after subsequent heat treatment transformed into hafnium carbide. The obtained materials were analyzed by means of X-ray diffraction and scanning electron microscopy. The results showed that the obtained carbide powders were composed of nearly equiaxed particles with narrow size distribution. Characterization by nitrogen adsorption showed that the obtained powders were micro- and mesoporous materials with high specific surface area.     

Project Tocoen. The Fate of Selected Organic Compounds in the Environment. Part XXVIII. Levels of PAHs and Some Halogenated POPs in Ambient Air in Czech Republic

Abstract

Concentrations of polyaromatic hydrocarbons (PAHs), chlorinated pesticides, polychlorinated biphenyls, dibenzo-p-dioxins and dibenzo-p-furans (PCDDs/Fs) in ambient air in Ko?etice, a background locality in the South Bohemia, have been estimated in the period from July to December 1994. The 24-hours samples have been taken by the means of a high-volume sampler. Sample analysis involved Soxhlet extraction of polyurethane foam, extract preconcentration and chromatographic clean-up procedure followed by HPLC determination of PAHs with fluorescence detection, GC/ECD determination of chlorinated pollutants, and GC/MS determination of PCDDs/Fs. The results of this first detailed study undertaken in Czech Republic are compared with the data obtained by similar projects in industrial and/or urban areas in the Czech Republic and in rural or urban areas in other European countries.     

Finite difference solution of the one-dimensional advection–diffusion equation with variable coefficients in semi-infinite media

One-dimensional advection–diffusion equation with variable coefficients in semi-infinite media is solved using explicit finite difference method for three dispersion problems: (i) solute dispersion along steady flow through inhomogeneous medium, (ii) temporally dependent solute dispersion along uniform flow through homogeneous medium, and (iii) solute dispersion along temporally dependent unsteady flow through inhomogeneous medium. The continuous point source of uniform nature is considered at the origin of the medium. Results are compared to analytical solutions reported in the literature and good agreement was found. We have shown that explicit finite difference method is effective and accurate for solving advection–diffusion equation with variable coefficients in semi-infinite media, which is especially important when arbitrary initial and boundary conditions are required.     

Hydrogen storage in Laves phases: First principles study of electronic structure and formation energies in HfV2 hydrides

We present first principles calculations of the electronic structure, enthalpies of formation and electric field gradients in C15 HfV₂H_x (x = 1, 2, 3, 4). In C15 Laves phases, hydrogen can occupy three possible interstitial positions: 96g, 32e, and 8b. To determine which one of these interstitials is the most favorable for storing hydrogen, enthalpies of formation were calculated for every site, with different concentrations of hydrogen. In order to investigate the change in electronic structure before and after hydrogenation, we calculated the electric field gradients induced by hydrogen on the vanadium, and compared them with the existing nuclear magnetic resonance measurements. This comparison enabled us to study the distribution of hydrogen atoms in the crystal lattice, as well as the occupation of possible interstitials.