Institute of Plant Nutrition and Soil Science

Natural shear forces due to gravity along inclined terrain surfaces are controlled by the inclination of the terrain, material composition and its mechanical properties, stratification and hydraulic stress states. Both shear forces and shear strength under a given inclination of the terrain surface strongly depend on the interaction between mechanical and hydraulic stresses. These internal conditions as well as the interactions between these various components are fundamentals in all nonplanar regions under arable, forest or grassland management and they dominate also under various geoscientific aims. Generally, soil creep is a slow soil movement downslope under gravity. It can occur even on gentle slopes when the shear forces exceed the shear strength of the soil. Deposited material on slopes is more sensitive to such movements than well-developed soils due to the absence of a pronounced soil structure, site and management dependent hydraulic properties and functions, which results in low soil strength. We applied the described measurements and the modelling approaches to investigate and to analyse the stability of an artificially constructed water catchment (Chicken Creek) in the mining district of Cottbus/ Germany, where glacial sand was deposited above a clay layer with an inclination of about 3.5%. At the lower part of the catchment, an impermeable barrier (clay wall) was positioned transversally to the main slope. Mechanical and hydraulic parameters of the soil layers were determined on soil samples taken from the field site. The measured values were inserted as input parameters for the finite element model (Plaxis 2D) to simulate soil movements and their effect on the stability of the catchment. The obtained results showed that the kind of construction negatively affected the physical low soil strength (low precompression stress) although the bulk density was very high (1.7-1.9 g/cm 3 for the sandy material). Hydraulic conductivity revealed a significant anisotropy with higher hydraulic conductivity values in the horizontal direction. Furthermore, finite element results showed that the design of the newly formed landscape remains weak concerning mass movements too. The high water table in the sandy material in conjunction with low soil strength enhances the downslope movement and increases the shear stress near the clay wall at the lower end of the slope, which finally results in soil creep processes. These results also proof that such geotechnical and modelling approach is also suitable to validate or to predict mass movements and the internal processes responsible for these internal mass erosion. 2014 Elsevier B.V. All rights reserved.

We present a replication process, named reversal soft ultraviolet (UV) nanoimprint, to fabricate a highaspect-ratio flexible subwavelength grating (SWG) on a polyurethane acrylate (PUA). This nanopatterning technique consists of casting, reversal UV imprint, and dry release. The UV curing process of PUA to avoid pattern collapse is investigated. Revalpha film acts as the supporting and sacrificial layer during the whole process due to its special surface energy property. The free-standing PUA structures with a period of 200 nm and a depth of 350 nm can be automatically released from the Revalpha film by heating. The PUA resist is well suited to replicate fine patterns of the mold with high aspect ratio and large area precisely and uniformly for low surface energy and low viscosity. The measured transmittance is compared with the calculation results based on rigorous coupled-wave analysis in the wavelength region ranging from 500 to 800 nm. The experimental results agree well with the theoretical calculations.

In this note, we present our results about the process design and characterization of deep reactive ion beam etching of high line density fused silica transmission gratings. Up to 1 μm deep and 1880 lines/mm microstructures have been successfully fabricated for 532nm ultrashort pulse laser pulse compression using the developed processes. Considering the requirements of the manufacturing process, a certain range of parameters needs to be determined to reduce the need for etching precision. Therefore, in this paper, the strict coupling wave method is used to determine the parameter range of the grating in the range of the calculated grating parameters, and the diffraction efficiency of the simplified mode method can be calculated. To our knowledge, this is the first note on the design parameters of transmission pulse compression grating made on fused quartz substrate are given using the simplified mode method to design and a non-ICP-based reactive ion etcher.

Foliar application of Mg is a measure for the correction of Mg deficiency in crop plants. Foliar applied nutrients need to access the symplastic side where majority of physiological processes take place. To achieve an adequate uptake of the Mg ions through the leaf surface, concentrations of 100-200 mM MgSO 4 are usually supplied. This can cause antagonistic perturbations on the subcellular distribution of Ca and K cations. To test for such unintended side effects, we used the infiltration-centrifugation method to extract ions from the apoplastic and symplastic side of Vicia faba leaves and quantified concentrations of Mg, Ca and K in dependency to the dose of the foliar fertilized Mg. Results show that a large fraction of Mg accesses the symplast whereas the apoplastic fraction shows a concomitant increase. Symplastic and apoplastic K and Ca relations were only affected under conditions of high exogenous leaf supply of Mg (200 mM) but did not change upon moderate Mg supply (50; 100 mM). Overall, results reveal the suitability of leaf fertilization to biofortify plant-based products with magnesium.

Na + accumulation in the leaf apoplast has been suggested to lead to dehydration, later wilting and finally, the death of the affected leaves. Our aim has been to evaluate whether the reduction in the plant growth of sensitive maize in response to salinity is correlated with higher amounts of Na + and Cl ) concentrations in the leaf apoplast. Subcellular ion patterns in intact leaves were investigated by using deionised water infiltration. We found an increase in soluble Na + and Cl ) concentrations of about 16-and 4-fold, respectively, compared with the control. These concentrations characterized the apoplasts of expanding leaves that had entirely developed under salinity. Interestingly, the K + concentration was significantly reduced by 64 % compared with its control in the symplast under salinity. Our finding of a significantly decreased Ca 2+ concentration in shoots suggested a possible association of Ca 2+ concentration with the reduction in leaf expansion under salinity. As the absolute increase in the apoplastic Na + concentration during salt treatment was much lower compared with the increase in the symplastic Na + concentration, salt treatment in maize appears not to result in osmotic stress imposed by a high apoplastic Na + concentration as has been suggested for other plant species (Oertli hypothesis).

Proteins in the plant apoplast are essential for many physiological processes. We have analysed and compared six different infiltration solutions for proteins contained in the apoplast to recognize the most suitable method for leaves and to establish proteome maps for each extraction. The efficiency of protocols was evaluated by comparing the protein patterns resolved by 1-DE and 2-DE, and revealed distinct characteristics for each infiltration solution. Nano-LC-ESI-Q-TOF MS analysis of all fractions was applied to cover all proteins differentially extracted by infiltration solutions and led to the identification of 328 proteins in total in apoplast preparations. The predicted subcellular protein localisation distinguished the examined infiltration solutions in those with high or low amounts of intracellular protein contaminations, and with high or low quantities of secreted proteins. All tested infiltration solution extracted different subsets of proteins, and those implications on apoplast-specific studies are discussed.

V /F M), as determined by chlorophyll fluores-Absorption at 505 nm and high-performance liquid chromatography showed that light-induced conversion of violaxanthin cence in nitrate-and ammonium-grown plants. Dithiothreitol decreased the light-induced stimulation of zeaxanthin forma-to antheraxanthin and zeaxanthin was much stronger in leaves of nitrate-than in leaves of ammonium-grown Phaseolus tion and increased photoinhibition in nitrate-grown plants, suggesting that these plants utilize zeaxanthin for the protec-7ulgaris. Feeding ascorbate via the petiole increased zeaxantion of photosystem II (PSII). Ammonium-grown plants seem thin formation in ammonium-grown plants. However, there was no difference in energy quenching, q E , or photoinhibition to have established an alternative way to protect PSII. nitrogen fixation and the related export of redox equivalents (Backhausen et al. 1994, Krö mer 1995, Noctor and Foyer 1998). Further, it was suggested that this greater PSI acceptor pool led to higher fluxes under limitation of carbon fixation (e.g., under light stress) and supported thylakoid energization and protection of PSII by energy quenching. In ammonium-grown plants, nitrogen metabolism cannot function as a PSI acceptor as N assimilation is carried out in the roots (Givan 1979). The findings of Vanselow (1993) in D. salina were supported by studies of Bendixen et al. (1997) in beans (Phaseolus 6ulgaris). However, Zhu et al. (2000) showed that the higher energy quenching in nitrate-grown plants occurs only at low light intensities, i.e., under conditions where differences in protection seem to be less important than under high light intensities. A survey of the variety of hypotheses considered to explain these observations is given by Zhu et al. (2000). These authors could rule out many of these models and considered a relationship to differences in the electron acceptors of PSI (Heineke et al. 1991, Champigny 1995, Noctor and Foyer 1998). On the basis of the scheme of Noctor and Foyer (1998) of interactions between chloroplasts, peroxisomes and mitochondria, they suggested that