Cassini imaging of Jupiter's atmosphere,satellites, and rings

The Cassini Imaging Science Subsystem acquired about 26,000 images of the Jupiter system as the spacecraft encountered the giant planet en route to Saturn. We report findings on Jupiter's zonal winds, convective storms, low-latitude upper troposphere, polar stratosphere, and northern aurora. We also describe previously unseen emissions arising from Io and Europa in eclipse, a giant volcanic plume over Io's north pole, disk-resolved images of the satellite Himalia, circumstantial evidence for a causal relation between the satellites Metis and Adrastea and the main jovian ring, and information on the nature of the ring particles.     

Solution structure of the integral human membrane protein VDAC-1 in detergent micelles

The voltage-dependent anion channel (VDAC) mediates trafficking of small molecules and ions across the eukaryotic outer mitochondrial membrane. VDAC also interacts with antiapoptotic proteins from the Bcl-2 family, and this interaction inhibits release of apoptogenic proteins from the mitochondrion. We present the nuclear magnetic resonance (NMR) solution structure of recombinant human VDAC-1 reconstituted in detergent micelles. It forms a 19-stranded beta barrel with the first and last strand parallel. The hydrophobic outside perimeter of the barrel is covered by detergent molecules in a beltlike fashion. In the presence of cholesterol, recombinant VDAC-1 can form voltage-gated channels in phospholipid bilayers similar to those of the native protein. NMR measurements revealed the binding sites of VDAC-1 for the Bcl-2 protein Bcl-x(L), for reduced beta-nicotinamide adenine dinucleotide, and for cholesterol. Bcl-x(L) interacts with the VDAC barrel laterally at strands 17 and 18.     

Einfluß von Wassergehalt und Salzen auf die Nitrifikation in Proben einer podsoligen Braunerde

Influence of watercontent and salts on the nitrification in samples of a Dystric Cambisol Samples of a Dystric Cambisol from a beech site produced nitrate but autotrophic nitrifying microorganisms could not be detected. Net nitrification of the humic layer and the upper 5 cm of the mineral soil during incubation at 22°C was investigated. Nitrification rate increased with increasing water content of the soil. Additions of ammonium or peptone did not increase the nitrification in the humic layer. Supply of (ammonium-)sulphates and chlorides with concentrations higher than 2 mMol per kg soil inhibited nitrification totally. This could not be ascribed to pH-changes. Additions of phosphates, lime or alkali to the soil samples increased nitrification.     

A 13C-NMR study on the formation of soil organic matter from grass residues

The development of C-distribution on functional groups in soil organic matter (SOM) was investigated in whole soil samples and organomineral particle-size fractions from the 34-year-old pot experiment Hu3-Loamy marl at Rostock. CPMAS-¹³C-NMR spectra of grass roots and whole soil samples indicated the enrichment of carboxyl-C, aliphatic C and aromatic C in SOM, Only minor changes were observed in the SOM-C distribution on functional groups between 13th and 34th experimental year. The investigation of organomineral clay and silt-size fractions showed a specific retention of aliphatics in clay. The most obvious changes in organic matter composition in size-fractions were the increase of carbohydrate-C and decrease of aromatic C.     

Verlagerung und Dispersion von Chlorid-, Bromid-, Nitrat- und SulfatTracern in zwei typischen Auenböden

Translocation and dispersion of chloride, bromide, nitrate and sulfate tracers in two typical Fluvi-Eutric Cambisols Chloride, bromide, nitrate and sulfate were applied as tracers on two weakly to moderately acidic Fluvi-Eutric Cambisols. The soil solution was sampled by ceramic suction cups down to a soil depth of 180 cm. At definite time intervals also soils material was taken from different depth to produce the soil saturation extract. The concentrations of the non-adsorbed anions chloride, bromide and nitrate were very similar in the suction cup solutions and in the saturation extracts, whereas the concentrations of the weakly adsorbed sulfate partially showed considerable differences. Obviously both methods extract in acid soils different fractions of the dissolved sulfate. By comparison of marked sulfate peaks with those of chloride, bromide or nitrate, which occur at the same time in different soil depth, a Kd value of 0.16 1/kg can be calculated for the Ap horizon and of 0.02 1/kg for the subsurface horizons of one Fluvi-Eutric Cambisol. Values of the dispersivity of the different horizons were estimated by varying the values of the dispersivity reported in the literature until the best fit of the simulated anion depth distribution to the measured values was found. The estimated dispersivities varied between 1.0 cm in the Ap horizon and 1.8 and 10.0 cm in the subsurface horizons.     

Impact of Fusarium culmorum on the polysaccharides of wheat flour

To assess the effects of Fusarium infection on the polysaccharides of winter wheat grain (Triticum aestivum L.), grain samples obtained from plants artificially inoculated with Fusarium culmorum were analyzed. Microscopy revealed obvious damage to the starch granules in the seriously infected samples. The Fusarium infection had no analytically detectable influence on the starch and total insoluble dietary fiber content of the wheat grain. There were significantly positive relationships between alpha-amylase activity, cellulase activity, total soluble dietary fiber content, pentosan content, and degree of infection quantified by an enzyme-linked immunosorbant assay, which would indicate the importance of fungal enzymes. A distinct higher Hagberg falling number (FN) was determined in the seriously infected samples, while the viscosity and sucrose content of the flour decreased. However, the addition of a liquid medium contaminated with F. culmorum led to a significant decrease in the FN. Depending on the type of buffer used, the alpha-amylase of F. culmorum demonstrated its maximum activity between pH 5.5 and pH 7.0 at 30-50 degrees C. Remarkably, this fungal alpha-amylase showed a thermostable characteristic and was active over a wide range of temperatures, from 10 to 100 degrees C. This type of thermostability suggests that the alpha-amylase of F. culmorum may damage starch granules throughout the processing of wheat flour, thereby inducing weak dough properties and unsatisfactory bread quality.     

Trends and uncertainties in anthropogenic VOC and NOx emissions

Water, Air, & Soil Pollution - Since 1900, NOx emissions appear to have steadily increased in nearly all areas of the country while emissions of nonmethane volatile organic compounds have...     

Measurement of residues and simulation of the movement of atrazine in deeper soil layers after long-term application in agriculture

The herbicide atrazine [2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine] was applied to corn at recommended rates over a period of 18 years until 1988. The investigated field was sampled down to a depth of 10 m in 1989 and 1991. In both years residues of atrazine were determined down to 10 m depth by HPLC-analysis of soil extracts in concentrations of up to 12 μg/kg. Batch-experiments were conducted to establish sorption isotherms of various soil layers. Numerical simulations of the migration of atrazine, based on the Richards-equation and the convection-dispersion-equation with first-order degradation were performed and compared to the measurements. Depth-dependent distribution of atrazine residues could be roughly reproduced by calculations, but the calculated depth-profiles of atrazine concentrations varied strongly within the variability of the sensitive parameters. The deterministic model used was therefore not able to predict the amount of pesticide residues in groundwater recharge precisely.     

Nitrat-Verlagerung in Auenböden unter organischer und konventioneller Bewirtschaftung — Meßergebnisse,Modellierungen und Bilanzen

Nitrate transport in soils of a river flood plain under organic and conventional farming — analytical results, modeling and balances Over a period of two years the transport of nitrate was investigated in Fluvi-Eutric Cambisols of a river flood plain of the Rhine tributary Sieg (Nordrhein-Westfalen, Germany). The soils were cultivated according to organic and conventional farming systems. Time series of NO₃ concentrations in soil solutions sampled by ceramic cups down to a depth of 180 cm are given. The interpretation of the results was possible by model calculations using the model DELPHI, which had been calibrated before by tracer experiments. N-mineralization and N-leaching were quantified. For different crop residues reaction coefficients for the mineralization of the easily decomposed organic material were calculated. They were extremely high for bean residues (19.0 × 10¹²) × exp (-9800/T) and mustard-vetch residues (12.0 × 10¹² × exp (-9800/T). The lowest reaction coefficient of 3.0 × 10¹² × exp (-9800/T) was calculated for the decomposition process during winter time. For the two farming systems a detailed N-balance was calculated. It is shown that under conventional farming over a time period of two years 199 kg N/ha were leached. Within the same period 53 kg N/ha were leached under organic farming. These differences depend in part on different crop rotation. Especially intercropping on the organically cultivated plots reduced the leaching of nitrate.