The vitelline membrane: Dynamics of cholesterol metabolism in hens' eggs

Changes in cholesterol levels in egg contents were studied to indicate trends and dynamics of processes of penetration through the vitelline membrane from yolk to egg white. Investigations were carried out on eggs stored for a period of 35 days at room temperature (22°C). Levels of free and esterified cholesterol were determined by the spectrophotometric method at 7-day intervals. The selective character of the vitelline membrane depends on conditions and period of storage. The study demonstrated that the vitelline membrane loses its selective nature between the twentieth and thirtieth days under particular conditions of storage. Following this period, a spontaneous penetration of cholesterol into the egg white is observed—i.e. the barrier equilibrium of the membrane becomes unstable. The presence of free cholesterol in egg white may be indicative of loss of egg freshness.     

Porous bead polyaromatic copolymers containing ester groups. II. The influence of the preparation conditions on surface properties of copolymers

Porous bead copolymers of styrene with 4,4′-di(methacryloyloxymethyl)diphenylmethane (DMD) have been prepared. Preparation conditions (composition of the monomer mixture with an inert component) were discussed with respect to the porous properties of copolymers (the specific surface area, pore size distribution and mean pore radius).     

Interfacial area in three-phase fluidized beds

On the basis of mass transfer models and the results of our previous investigations, Danckwerts' pseudo-first order reaction method was adapted for the determination of interfacial area in a three-phase fluidized bed. The results of our experimental investigations on the absorption of carbon dioxide in aqueous sodium hydroxide are presented. The works of other authors are analysed.     

Generation of directed cotrees formulated in Wang's algebra

The construction of a directed graph for a network described by an impedance matrix is presented. This graph has a structure similar to that of the network. The analysis is based on the generation of directed cotrees, which are dual to the directed trees.     

Effects of hydrostatic pressure on phase and group modal birefringence in microstructured holey fibers

We calculated the sensitivity of phase (dB/dp) and group (dG/dp) modal birefringence to hydrostatic pressure versus wavelength in two birefringent holey fibers of different construction, where B is the phase modal birefringence, G is the group modal birefringence, and p is the pressure applied to the fiber. The contributions of the geometrical effects that were related only to deformation of the holey structure and the stress-related contribution to the overall pressure sensitivities were analyzed separately. Our results show that these two factors decrease the phase modal birefringence in both structures, which results in negative signs of dB/dp and dG/dp. Furthermore, we demonstrate that the geometrical effects are much weaker than the stress-related effects and contribute only a few percent to the overall pressure sensitivity.     

Processing of Copper‐Containing Steel via Strip Casting ‐ a Laboratory Evaluation

Copper in recycled steel made from scrap is well known to create problems of hot shortness during rolling. The present study was carried out to ascertain how the situation could be improved when using strip casting in conjunction with direct hot rolling. This has included steels having copper contents up to 2.5 wt.% and in some cases also tin levels up to 0.1 wt.%. Laboratory simulations have been carried out to simulate the process conditions from the outlet of the strip caster through hot rolling, and the resulting materials have been examined with regard to their hot cracking behaviour and microstructural condition. Mechanical properties have also been measured on samples having different simulated coiling temperatures after hot deformation. Conditions can be established to avoid hot shortness even in steel containing high copper contents, due to the short time that is available for oxidation. Depending on the steel composition and coiling temperature, it is possible to achieve very significant strengthening due to precipitation of copper‐rich particles.     

Investigations of corrosion resistance of Fe-, Ni- and Co-based hardfacings

In the present paper, the potential of surface coatings to increase corrosion of internal combustion engine valves is discussed. The corrosion tests were carried out to study in simulated engine chamber environment the performance of Ni-, Co- and Fe-based materials used for plasma deposition. Hot corrosion tests were performed in air, sulphur dioxide containing atmosphere and in molten synthetic ash. The crucible-sorting test was used to simulate deposits on valve seats from residual fuel combustion which are responsible for rapid corrosion due to the presence of molten phase. The new alloys containing Ni and Co can be potentially applied as valve hardfacings.