Pretkoncentracija mikroelemenata iz vode koristeći 4-morfolin ditiokarbamat

The optimum conditions were found for the preconcentration of trace metals in natural waters and model samples with standard metals concentrations by using 4-morpholine dithiocarbamate. The formed complexes were extracted with chloroform. Different methods for recovering the metals from the organic solvent were studied and compared before AAS metal analysis. The developed preconcentration method was successfully applied to the determination of trace metals concentrations in water samples from the "Barje" lake (Leskovac. Yugoslavia).Nađeni su optimalni uslovi za pretkoncentraciju mikroelemenata iz vode koristeći 4-morfolin ditiokarbamat kao kompleksirajući agens. Nagrađeni kompleksi su ekstrahovani hloroformom. Upoređeni su različiti načini ekstrakcije metalnih jona iz organskog rastvarača pre analize atomskom apsorpcionom spektrofotometrijom. Razvijena metoda za pretkoncentraciju uspešno je primenjena za analizu uzoraka vode jezera Barje (Leskovac Jugoslavija)

Physico-chemical characterization of mixed-ligand complexes of Mn(III) based on the acetylacetonate and maleic acid and its hydroxylamine derivative

Two new Mn(III) mixed-ligand complexes with two acetylacetonate (acac) ligands and one maleate ligand and its hydroxylamine derivative of the general formula [Mn(C5H7O2)2L] were prepared. Their structure was established by using elemental analysis, FTIR and UV/VIS spectroscopic methods, as well as magnetic measurement. Replacement of the acetylacetonate ligand by the corresponding acid ligand has been confirmed in Mn(III) acetylacetonate. Based on the obtained experimental data and literature indications, structural formulae to these compounds were assigned

Discocotyle ohridana n. Sp. (monogenea: Discocotylidae) on the gills of ohrid belvica salmothymus ohridanus (pisces: Salmonidae) from the lake ohrid, macedonia

Discocotyle ohridana n.sp. is described from the gills of Ohrid belvica Salmothymus ohridanus Steindachner, 1892; (syn. Acantholingua ohridana Hadzisce, 1961) from the Lake Ohrid, Macedonia. According our investigation the new species D. ohridana n.sp. differs 56.47% of observed S. ohridanus have been infected and average intensity of infestation is 2.84

Study of the catalytic selectivity of an aqueous two-component polyurethane system by ftir spectroscopy

The difficulty in formulating a two component waterborne polyurethane, is the isocyanate-water side reaction, which can lead to gassing/foaming, loss of isocyanate functionality, low gloss and a reduced pot life. To compensate for this side reaction, these formulations usually contain a large excess of isocyanate. Tin compounds, especially dibutyltin dilaurate, are widely used in coatings as catalysts for the isocyanate/hydroxyl reaction. Because of the high aquatic toxicity of some organotin compounds, there has been an attempt to ban organotin compounds from all coating applications. As a general rule, organotin catalysts are not selective, they catalyze the reaction of isocyanates with both hydroxyl groups and water and also catalyze the hydrolysis of ester groups. One novel approach to control the water side reaction is the use of catalysts which selectively catalyze the isocyanate-polyol reaction and not the isocyanate-water reaction. The selectivity of a variety of metal catalysts (metal octoates, metal acetylacetonates and mangan chelates with mixed ligands) to catalyze the preferred reaction was measured using the FTIR method

Parasitofauna of the Ohrid trout (Salmo letnica Karaman, 1924) from Lake Ohrid (Macedonia)

In the period from April, 1995 to March, 1996, 131 specimens of the Ohrid trout (Salmo letnica, Karaman) 1924 from the Macedonian part of Lake Ohrid were examined parasitologically. A total of 99 fishes (75.57%) were found to be infected. The presence of 6 parasite species: Diclybothrium sp., Eubothrium crassum, Eubothrium salvelini, Cyathocephalus truncatus, Proteocephalus neglectus and Pomphorhynchus laevis. The highest prevalence occurred with Eubothrium crassum (48.09%) and the lowest with Pomphorhynchus laevis (0.76%). The greatest number of parasite specimens was found in the cases of infection with Eubothrium crassum (55) followed by Proteocephalus neglectus (45) and Cyatocephalus truncatus (40). Fultons condition coefficient among the infected fishes was 1.03 (average) and among the uninfected trouts it was 1.10. A high prevalence (75.57%) was noted which was higher than in other fish species of Lake Ohrid. The finding of 3 parasite species mentioned in our study. is the first time they have been detected among the parasitofauna of Lake Ohrid and Macedonia: Diclybothrium sp., Eubothrium salvelini and Proteocephalus neglectus. From the results of our investigations, we can add a new host, Salmo letnica, for some parasite species: Diclybothrium sp., Eubothrium salvelini, Cyathocephalus truncatus, Proteocephalus neglectus and Pomphorhynchus laevis to the list of known hasts

Fauna monogenih trematoda-parazita nekih riba roda cyprinidae iz Prespanskog jezera, Makedonija

During parasitological investigations six species of monogenean trematodes were found on the gills of three cyprinid fish species from Lake Prespa (Macedonia), as follows: Dactylogyrus prostae and Dactylogyrus sphyrna in Leuciscus cephalus albus, Dactylogyrus erhardovae, Dactylogyrus sphyrna and Paradiplozoon zeller in Rutilus rubilio prespensis and Dactylogyrus elegantis and Dactylogyrus vistulae in Chondrostoma nasus prespensis. The prevalence in Leuciscus cephalus albus was 62.22%, in Rutilus rubilio prespensis 59.87% while in Chondrostoma nasus prespensis it was the lowest and amounted to 41.59%. The overall, prevalence of monogeneans in the investigated cyprinid fishes from Lake Prespa was 53.65%, and the mean intensity of infestation was 6.08. Among the monogenean species the highest prevalence occurred with Dactylogyrus sphyrna (25.08%), and the greatest intensity of infestation was evident in the cases of infestation with Dactylogyrus erhardovae (12.87). The greatest pathological effect was associated with the monogeneans Dactylogyrus vistulae and Paradiplozoon zeller. All monogenean species found represented the first record for such parasite fauna of fishes in Macedonia.U toku parazitoloških istraživanja ciprinidnih riba iz Prespanskog jezera (Makedonija), kod 3 vrste riba na škrgama pronađeno je 6 vrsta monogenih trematoda, i to: kod Leuciscus cephalus albus su nađeni Dactylogyrus prostae i Dactylogyrus sphyrna, kod Rutilus rubilio prespensis su pronađeni Dactylogyrus erhardovae, Dactylogyrus sphyrna i Paradiplozoon zeller, kod Chondrostoma nasus prespensis su pronađeni Dactylogyrus elegantis i Dactylogyrus vistulae. Ekstenzitet infestacije kod Leuciscus cephalus albus iznosio je 62,22%, kod Rutilus rubilio prespensis 59,87%, a kod Chondrostoma nasus prespensis je bio najniži i iznosio je 41,59%. Ukupno, ekstenzitet infestacije sa monogeneama kod ispitivanih ciprinidnih riba Prespanskog jezera iznosio je 53,65%, a intenzitet infestacije 6,08. Pojedinačno, po vrstama monogenea, najviši ekstenzitet infestacije je bio sa Dactylogyrus sphyrna (25,08%), a najviši intenzitet infestacije je utvrđen u slučajevima infestacije sa Dactylogyrus erhardovae (12,87). Najveći patogeni uticaj su imale monogene trematode Dactylogyrus vistulae i Paradiplozoon zeller. Sve pronađene vrste monogenea predstavljaju prvi nalaz za parazitofaunu riba Makedonije

New Organic Solvent Free Three-Component Waterproof Epoxy-Polyamine Systems

The unmodified GY epoxy resin (Vantico AG) was crosslinked by the aliphatic and cycloaliphatic EH polyamine adduct (Solutia-Vianova) in the different stoichiometric ratio. The optimal time of total crosslinking was determined by indirect measuring of the film hardness. The degree of the epoxy resin crosslinking and the quantity of unreacted epoxy groups have been monitored by the spectroscopic FT-IR method. The content and intensity changes of hydroxy group were correlated to the extent of epoxy reaction and crosslinking degree. By the parameters correlation and a period of resins application, optimal resin/hardeners stoichiometric ratio was defined. It was prerequisite for three-component epoxy system forming which is comparatively more elastic, adhesion and waterproof