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From November 1995 to October 1996 and from October 1997 to September 1998, samples of wet precipitation, cloud water as well as of reactive gases and particulate matter, were collected at three elevational levels (920 m, 1,280 m and 1,758 m a.s.l.) in Achenkirch, Austria. The samples were analysed for ammonium and nitrate in wet precipitation and in cloud water, for ammonia, nitric acid and nitrogen dioxide in the gas phase and for particulate ammonium and particulate nitrate in aerosol. Total nitrogen deposition was calculated combining measured concentrations in wet, dry and occult depositions with the corresponding deposition fluxes. Two multilayer deposition models were used for the calculation of dry and occult deposition. The total nitrogen input in 1995/96 was estimated to be 29 kg N ha(-1)a(-1) at the Christlumkopf station (1,758 m), 20 kg N ha(-1)a(-1) at the Christlumalm station (1,280 m) and 28 kg N ha(-1)a(-1) at the Talboden station (930 m). Respective data for the 1997/98 observation period were 31 kg N ha(-1)a(-1) at the Christlumkopf station (1,758 m) and 18 kg N ha(-1)a(-1) at the Mülhleggerköpfl station (920 m). Critical Loads of nitrogen for coniferous forests were exceeded significantly near-source regions represented by areas of intense agricultural use and at high elevation sites.

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Passive samplers were used to monitor ammonia concentrations at rural inner alpine and pre-alpine, as well as urban, sites in Austria and Bavaria. Elevated concentrations were measured both at farms (up to 36 microg NH3 m(-3)) and at urban locations (up to 28 microg NH3 m(-3)). At urban locations a linear relationship between the traffic density and the NH3 concentration was found, but there was no marked seasonal trend. The highest ammonia concentrations were measured in a traffic tunnel (up to 78 microg NH3 m(-3)). The presence of livestock breeding or small scale alpine pastures resulted in elevated concentrations at the rural sites (8.1-12 and 2.5-4.6 microg NH3 m(-3), respectively), compared to the surrounding areas (3.1 and 0.9 microg NH3 m(-3)). Agriculture related sources are usually limited either spatially or seasonally. As the emissions were moderate in our case, a rapid removal and dilution of ammonia was possible and therefore the NH3 burden was only local. Sources related to traffic are more evenly distributed both geographically and seasonally. The WHO guideline, annual average concentration of 8 microg m(-3) for the protection of vegetation, was only exceeded at farms, at the urban station with the heaviest traffic and in the Tauerntunnel.

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The components of segmented polyurethanes having polyether "soft segments" and aromatic diisocyanate-diamine "hard segments" were studied separately and in the form of segmented polyurethanes. Platelet retention index (the capacity of the polymer to bind human platelets) was studied in relation to properties determined by scanning calorimety, Fourier transform infrared spectroscopy, gel permeation chromatography, and x-ray photoelectron spectroscopy. Carbon 1s spectra, which differentiate carbon bound to ether oxygen from other carbon in the outermost 30 Å of the surface, predicted platelet retention to a remarkable degree. In general, the hard segment analogues have high platelet retention. As a soft segment, poly(ethylene oxide) showed very low platelet retention. S egmented polyether polyurethanes are widely studied biomaterials that can be conceptualized (1-3) as a virtual network in which thecontinuous phase contains the polyether chain molecules. These chain molecules are tied at their ends to the molecular, species (diisocyanate, diamine) which serve as junctions by associating into clusters. These clusters of high melting point form "the hard-segment phase" and are dispersed in the continuous polyether phase.In global overview of what was discovered, we note the following:1. Molecular models (2 ) of the hard-segment phase of segmented polyether polyurethanes tested in the in vitro bead column (4) show a high platelet retention index (p = 0.8) regardless of molecular composition. The variable ρ is defined as the frac tion of platelets in whole citrated human blood entering a test column that are retained on the bead surfaces, averaged for