Gibt es ungiftige Schädlingsbekämpfungsmittel?

Ohne Zusammenfassung     

Initial pesticide residues in relation to vapour pressure

Field tests, in which several insecticides were applied at equal rates by ground sprayer to oats, rye and alfalfa, showed that residues 1 h after application were much lower for highly volatile compounds than for those of lower volatility. Varying the distance from spray release to target canopy from 10 to 40 cm did not significantly affect the deposits. Results indicate that applying insecticides with a vapour pressure greater than about 10^?4 mmHg (20°C) in aqueous media is very inefficient.     

Volume and texture improvement of gluten-free bread using quinoa white flour

Patients suffering from coeliac disease have to avoid traditional cereals-based products and depend on the availability of gluten-free alternatives. The gluten-free bread matrix and its foam stability are strongly affected by the choice of ingredients. In this study, the impact of quinoa white flour on bread quality parameters, in particular volume, has been investigated. The pseudocereal proved to be a suitable substrate for dough aeration using yeast, since considerably more glucose and a higher activity of α-glucosidase were found in comparison to rice and corn flour. Consequently, quinoa white flour was used to replace 40–100% of the rice and corn flour in a gluten-free control recipe. As a result, quinoa white flour enhanced the specific volume by 33%, which was related to the absence of bran components and the increased α-glucosidase activity. The significance of the latter was proven by separately adding sucrose and fungal amyloglucosidase to the control recipe. Moreover, the crumb featured homogeneous and finely distributed gas bubbles and the taste was not compromised. Thus, it was possible to improve the quality of gluten-free bread by using quinoa white flour, which might be a relief for coeliac patients.     

MHC class I peptides as chemosensory signals in the vomeronasal organ

The mammalian vomeronasal organ detects social information about gender, status, and individuality. The molecular cues carrying this information remain largely unknown. Here, we show that small peptides that serve as ligands for major histocompatibility complex (MHC) class I molecules function also as sensory stimuli for a subset of vomeronasal sensory neurons located in the basal Gao- and V2R receptor-expressing zone of the vomeronasal epithelium. In behaving mice, the same peptides function as individuality signals underlying mate recognition in the context of pregnancy block. MHC peptides constitute a previously unknown family of chemosensory stimuli by which MHC genotypic diversity can influence social behavior.     

Effects of Forest Management on Nitrate Concentrations in Seepage Water of Forests in Southern Bavaria,Germany

We performed seepage water studies in three forested study areas in Southern Bavaria, Germany in order to identify forest management effects on nitrate concentrations. In total 95 stands representing different age classes (up to 100 years), tree species (mainly spruce and beech) and regeneration methods (from clearcut to single tree selection) were included. In the period between 1998 and 2000, water samples were taken from below the rooting zone with tension lysimeters and nitrate concentration was determined. Average nitrate concentrations were calculated for each stratum (stand age, tree species, regeneration method). These data were combined with forest inventory data in order to predict regional nitrate leaching. Nitrate concentrations were generally higher in mature spruce stands than in mature beech stands. In spruce stands, we observed a clear age-related pattern, with negligible nitrate concentrations in stands younger than 40 years and higher concentrations in older stands. In beech stands nitrate concentrations were low and independent of age. In clearcut areas nitrate concentrations were significantly higher than in areas treated with small-scale regeneration methods. Forest management effects were highest in the study area with the highest N-input and lowest in the study area with the lowest N-input and highest N-retention capacity. In general changes of forest management have mainly long-term effects. The reduction of nitrogen deposition remains a crucial factor in avoiding increased nitrate leaching into forest groundwater resources.

     

Die Umwandlung der glimmerartigen Schichtsilikate zu aufweitbaren Dreischicht-Tonmineralen

The transformation of mica-like layer silicates to expansible three-layer day minerals First of all a preliminary survey is given of those authors who have so far carried out investigations on certain minerals about transformations of layer-silicates to expansible three-layer clay minerals. It can be deduced from these investigations that the most important presupposition for a transformation, is the setting free of potassium and the reduction of the layer-charge. The knowledge of the presuppositions of a transformation was achieved mainly in model tests (deposit-clays), which also explain the running off of the exchanges of the intermediate layers. To demonstrate transformation processes with natural clay fractions of soils, requires an extensive clay fractionizing which is accomplished by means of centrifuges. Personal investigations with fractionized clays of a Chernozem have shown, that in soils, the transformation of illite into expansible three-layer-minerals occurs at the same time as the decrease in size of grain. Although the illites which are in the process of transformation reach an expansion up to 18 A from about 0,2 μ granular size, a qualitative difference exists (layer-charge, contraction tendency) to the genuine montmorillonites, that only becomes less at the finest fractions > 0,01 μ. The investigations with other soils (‘gray brown-soils’,‘acidic brown soil’) however, reveal that there is no suitable transformation scheme for all soils. Depending on the milieu in which the soil development has taken place, characteristic transformation sequences result. Because of the hitherto existing results three development-models were introduced and discussed, each of which led to different end-products.