Statistical Modeling of the Partitioning of Nonylphenol in Soil

Partition coefficients K _P of nonylphenol (NP) in soil were determined for 193 soil samples which differed widely in content of soil organic carbon (SOC), hydrogen activity, clay content, and in the content of dissolved organic carbon (DOC). By means of multiple linear regression analysis (MLR), pedotransfer functions were derived to predict partition coefficients from soil data. SOC and pH affected the sorption, though the latter was in a range significantly below the pK_a of NP. Quality of soil organic matter presumably plays an important but yet not quantified role in sorption of NP. For soil samples with SOC values less than 3 g kg^?1, model prediction became uncertain with this linear approach. We suggest that using only SOC and pH data results in good prediction of NP sorption in soils with SOC higher than 3 g kg^?1. Considering the varying validity of the linear model for different ranges of the most sensitive parameter SOC, a more flexible, nonlinear approach was tested. The application of an artificial neuronal network (ANN) to predict sorption of NP in soils showed a sigmoidal relation between K _P and SOC. The nonlinear ANN approach provided good results compared to the MLR approach and represents an alternative tool for prediction of NP partitioning coefficients.     

Improvement of the method for propagation,larval and postlarval rearing of the wels (Silurus glanis L.)

Using the old method of spawning it is impossible to produce wels larvae in quantities sufficient for a special fry farm economically. Because of this, a large-scale intensive method had to be developed, similar to those for other species which are propagated in hatcheries. A method for storing breeders was elaborated which included sewing their mouths shut and consequently eliminating injuries. Pituitary treatment — practised by others before — was applied, and disadvantages of the method (such as the development of furuncles) eliminated. A method for taking sperm from males with the help of a special syphon was developed.To avoid losses, larvae were reared in basins until they reached the size of 2–2.5 cm. Using this method considerable quantities of fry were produced in our hatchery.     

Studies on the antifungal action of potential steroid inhibitors

Structure-activity relationships were studied with macrocyclic esters of N,N′-ethylenebis-(2,2′-amino-1,1′-cyclopentene-1,1′-dithiocarboxylic acid), with compounds related to α-(2,4-dichlorophenyl)-α-phenyl-5-pyrimidinemethanol (triarimol) and with N-substituted imidazoles, all known or supposed to exert antifungal action by inhibiting the function or biosynthesis of fungal sterols.     

Demonstration of Clostridium septicum infection in a goose flock.

Clostridium septicum infection causing 5.0 to 5.2% mortality is reported for the first time in the literature from six-week-old growing geese in three flocks comprising 5,200, 5,500 and 5,900 geese, respectively. The affected birds exhibited weakness, uncoordinated movement, ataxia and, frequently, oblique position of the head and neck (torticollis) as well as signs indicative of dysequilibrium. The affected birds died within 18-24 h. Gross pathological examination revealed anaemia, hepatitis with map-like necroses of irregular outline (Fig. 1), acute enteritis, pulmonary oedema and cardiac dilatation. Light and electron-microscopic examination showed that the sinusoids of the liver were markedly dilated (Fig. 2) and filled with serous exudate and gas (Figs 2 and 3), and the hepatocytes surrounding them exhibited severe oedema (Fig. 4). Among the hepatocytes, ciliated bacteria 7-10 mu in length and 1-3 mu in width, bounded by a well-defined cell wall and often showing signs of spore formation were observed (Figs 5 and 6). By bacteriological examination the pathogen was isolated, its properties were studied, and the clinical entity of malignant oedema was experimentally reproduced by intramuscular injection of guinea-pigs and rabbits. The applied antibiotic (oxytetracycline) and furazolidone therapy proved effective.