The prevalences of Cryptosporidium parvum, rotavirus, bovine coronavirus (BCV), and enterotoxigenic Escherichia coli (E coli K99) were determined in diarrhoeic dairy calves aged one to 21 days on 71 dairy farms in western Switzerland during the winter of 2005 to 2006. Faecal samples from 147 untreated calves suffering from acute diarrhoea were analysed by standardised diagnostic methods, and the immunoglobulin status of each calf was evaluated. The prevalences of C parvum, rotavirus, BCV and E coli k99 were 55.0 per cent, 58.7 per cent, 7.8 per cent and 5.5 per cent, respectively. The proportions of herds positive for the respective pathogens among the herds with diarrhoeic calves were 41.7 per cent, 52.1 per cent, 2.1 per cent and 2.1 per cent. The immunoglobulin concentration in the serum of 90.5 per cent of the diarrhoeic calves was below 8 g/l.

The seroprevalence of pestivirus infections in small ruminants and new world camelids in Switzerland was determined. In 5'059 sera of sheep from 382 herds, 503 sera of goats from 54 herds and 109 sera of alpacas and lamas from 53 herds, population prevalences of 16.1% (sheep), 25.4% (goats) and 4.6% (new world camelids), respectively, were found. In order to determine the source of infection, the serological reactions were further characterized by cross-neutralization against two pestiviruses representing the genotypes BVDV (Bovine Virus Diarrhea Virus)-1 and BDV (Border Disease Virus)-1. Based on the ratio of respective antibody titres, 56.1% of the infections in sheep were induced by a BDV-1, 12.9% by a BVDV-1 and 31.0% by an unresolved pestivirus. In goats, the corresponding proportions were 23.4%, 10.2% and 66.4%, respectively. In Alpacas and Lamas, the source of infection of 1 animal was BDV-1 and that of 4 seropositive animals remained unresolved. In view of the phylogenetic relationship between pestiviruses, the unresolved source of infection is most probably attributable to other pestivirus genotypes circulating in small ruminants and new world camelids. Due to the predominance of pestiviral genotypes other than BVDV-1, the risk of transmission of BVDV from persistently infected small ruminants and new world camelids to cattle appears to be moderate, apart from close direct contact in mixed animal husbandry, communal pasturing and grazing in the Alps.

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Equilibrium yields for CVD of AlN dependent on the input ratio AlCI,/NH, and on temperature were computed (A) for AlCl, + NH, $ AlN + 3 HCl; (B) for additional complexing AlCI, + NH, + AlCl, . NH, at substrate temperature which did not result in changes of yield above 900 "C;(C) for AlC1, . NH, + AlN + 3 HCI corresponding to complete inhibition of dissociation near the substrate of the complex formed or preformed at lower temperature which resulted in considerably lower yields. A corresponding decrease of experimental results occurred within reactors having a long AlC1,-NH,-mixing zone at 350 "C or AlC1,. NH,-input with respect to a reactor with a short mixing zone near to the subst,rate. The dissociation of the complex present in the former t,wo cases was inhibited considerably. -This investigations demonstrate the additional influence of homogeneous reactions, which has to be regarded for CVD especially with complexing reactants in connection with the role of reactor geometry, a problem being increasingly discussed at present.Gleichgewichtsausbeuten werden fur die A1N-Ablagerung in Abhiingigkeit vom Eingangsverhaltnis AlCl,/NH, und von der Temperat,ur berechnet :

Reaction mixtures of the tetrahydrofuran adducts of Zn(CH3)2 and Zn(C2H5)2 with tertiary butanol are very well suitable for the MOCVD of c‐axis oriented ZnO films. The deposition process is greatly determined by the kind of the gas inlet into the vertical reactor. The growth rates present a great dependence on temperature. The incorporation of compensating copper acceptors can be achieved with the help of cyclopentadienyl (tributylphosphine)‐copper (I). The structural and the electrical properties of the films are presented.

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