The paper presents the initial results of investigation concerning the abrasion resistance of cast iron with nodular, vermicular, or flake graphite. The nodular and vermicular cast iron specimens were cut out of test coupons of the IIb type with the wall thickness equal to 25 mm, while the specimens made of grey cast iron containing flake graphite were cut out either of special casts with 20 mm thick walls or of the original brake disk. The abrasion tests were carried out by means of the T-01M tribological unit working in the pin-on-disk configuration. The counterface specimens (i.e. the disks) were made of the JT6500 brand name friction material. Each specimen was abraded over a distance of 4000 m. The mass losses, both of the specimens and of the counterface disks, were determined by weighting. It was found that the least wear among the examined materials was exhibited by the nodular cast iron. In turn, the smallest abrasion resistance was found in vermicular cast iron and in cast iron containing flake graphite coming from the brake disk. However, while the three types of specimens (those taken from the nodular cast iron and from grey cast iron coming either from the special casts or from the brake disk) have almost purely pearlitic matrix (P95/Fe05), the vermicular cast iron matrix was composed of pearlite and ferrite occurring in the amounts of about 50% each (P50/Fe50). Additionally, it was found that the highest temperature at the cast iron/counterface disk contact point was reached during the tests held for the nodular cast iron, while the lowest one occurred for the case of specially cast grey iron.

The HAp (hydroxyapatite) excellent ion exchange resin and has adsorption properties of heavy metals and organic materials. It is used as an adsorption material and as an organic drug-delivery material due to these characteristics, that are essentially controlled the specific surface area. In this paper, the specific surface area was controlled by adding polymers of polyvinylpyrrolidone (PVP), polystyrene beads (PSB), and polyethylene glycol (PEG). Through the USP process, the HAp powder is able to synthesize into the spherical shape, specific surface area, and pore were controlled by the properties of the polymers.

Observations were carried out in apple orchards and nurseries of the Plovdiv region (Central-South Bulgaria), aimed at determining specific composition, population density and economic importance of particular species of aphids, in the years 2004–2006. By surveys, carried out at 15-day intervals, the appearing species were identified and the degree of damage determined. Six species of aphids were found: Aphis spiraecola Patch., A. pomi Deg., Dysaphis plantaginea Pass., D. devecta Wlk. Rhopalosiphum insertum Wlk. and Eriosoma lanigerum Hsm. A. spiraecola, a poliphagous pest, was probably brought with the plant material from Greece and was identified in Bulgaria for the first time. It is similar to A. pomi and may be distinguished only by the microscopic investigation. Aphis spiraecola replaced almost completely A. pomi in the region studied. Its population was particularly high in nurseries. In the bearing orchards D. plantaginea was the most important aphid. Some tendency to an increase of population and damage caused by D. devecta was also noted. The other species had not any economic importance. E. lanigerum was present only in the orchards where no chemical control was applied.