Leibniz University of Hanover

About: Leibniz University of Hanover is a education organization based out in Hanover, Niedersachsen, Germany. It is known for research contribution in the topics: Finite element method & Population. The organization has 14283 authors who have published 29845 publications receiving 682152 citations.

Pectin methylesterase modulates aluminium sensitivity in Zea mays and Solanum tuberosum

Abstract: Cell suspension cultures of Zea mays L. were adapted to grow under conditions of NaCl stress, which increased the cell-wall pectin content of these cells by 31% compared with unadapted cells (controls). Both cultures were treated for 5 or 10 min with pectin methylesterase (PME) and afterwards incubated in the presence of Al for 2 h. The different capabilities of the cells to synthesise callose due to pre-treatment were taken into account by calculating relative Al-induced callose induction (digitonin = 100%). Only in salt-adapted cells with a degree of methylation of cell-wall pectin (DM) decreasing from 34% (control) to 13%, did PME treatment enhance total and BaCl 2 -non-exchangeable Al contents and Al sensitivity as indicated by increased callose formation. In a further step, a wider variation in DM was achieved by subculturing the NaCI-adapted cells for up to 3 weeks without NaCI supply and adapting them to the cellulose-synthesis inhibitor 2,6-dichlorbenzonitrile (DCB). This reduced DM to 26%, while short-term treatment with pectolyase resulted in the lowest DM (12%). After the 2 h Al treatment, there was a close negative relationship between DM and relative callose formation of Al contents, with the exception of pectolyase-treated cells. In addition, intact plants of Solanum tuberosum L. genotypes were characterised for their Al sensitivity in hydroponics using root elongation, Al-induced callose formation and Al contents of root tips as parameters. Based on all three parameters, the transgenic potato mutant overexpressing PME proved to be more Al-sensitive than the wild type, the Al-resistant and even the Al-sensitive potato cultivar. Especially in the root tips (1 cm), Al treatment (2 h, 50 μM) increased the activity of PME more in the Al-sensitive than in the Al-resistant genotypes. The presented data emphasise the importance of the DM of the pectin matrix and the activity of PME for the expression of Al toxicity and Al resistance.

Palms tracking climate change

Abstract: Aim Many species are currently expanding their ranges in response to climate change, but the mechanisms underlying these range expansions are in many cases poorly understood. In this paper we explore potential climatic factors governing the recent establishment of new palm populations far to the north of any other viable palm population in the world. Location Southern Switzerland, Europe, Asia and the world. Methods We identified ecological threshold values for the target species, Trachycarpus fortunei, based on gridded climate data, altitude and distributional records from the native range and applied them to the introduced range using local field monitoring and measured meteorological data as well as a bioclimatic model. Results We identified a strong relationship between minimum winter temperatures, influenced by growing season length and the distribution of the palm in its native range. Recent climate change strongly coincides with the palm's recent spread into southern Switzerland, which is in concert with the expansion of the global range of palms across various continents. Main conclusions Our results strongly suggest that the expansion of palms into (semi-)natural forests is driven by changes in winter temperature and growing season length and not by delayed population expansion. This implies that this rapid expansion is likely to continue in the future under a warming climate. Palms in general, and T. fortunei in particular, are significant bioindicators across continents for present-day climate change and reflect a global signal towards warmer conditions.

Multilinear pose and body shape estimation of dressed subjects from image sets

Abstract: In this paper we propose a multilinear model of human pose and body shape which is estimated from a database of registered 3D body scans in different poses. The model is generated by factorizing the measurements into pose and shape dependent components. By combining it with an ICP based registration method, we are able to estimate pose and body shape of dressed subjects from single images. If several images of the subject are available, shape and poses can be optimized simultaneously for all input images. Additionally, while estimating pose and shape, we use the model as a virtual calibration pattern and also recover the parameters of the perspective camera model the images were created with.

Mesostructured Pt/TiO2 Nanocomposites as Highly Active Photocatalysts for the Photooxidation of Dichloroacetic Acid

Abstract: Mesoporous Pt/TiO2 nanocomposites have been synthesized by using two pathways: (1) the in-situ preparation of Pt/TiO2 nanocomposites was carried out using a one-step synthesis by dissolving the Pt and TiO2 precursors in the presence of a triblock copolymer as the structure-directing agent followed by drying, calcinations, and reduction under H2 gas. (2) Platinum particles have been photochemically deposited onto mesoporous TiO2. The TEM images of the mesoporous Pt/TiO2 nanocomposites calcined at 450 °C demonstrate that the TiO2 nanoparticles with an average diameter of about 10 nm are not agglomerated and are quite uniform in size and shape. Following the photodeposition process, the Pt nanoparticles are well-dispersed and highly uniform, exhibiting diameters of ∼3 nm; however, following the in situ preparation, the Pt particles are reaching diameters of approximately 15 nm, most likely as a result of the calcination and reduction at high temperatures. The photocatalytic activity of the newly synthesized ...

NMR and impedance studies of nanocrystalline and amorphous ion conductors: lithium niobate as a model system.

Abstract: Lithium niobate has been chosen as a model system for spectroscopic studies of the influence of different structural forms and preparation routes of an ionic conductor on its ion transport properties. The Li diffusivity in nanocrystalline LiNbO3, prepared either mechanically by high energy ball milling or chemically by a sol-gel route, was studied by means of impedance and solid state 7Li NMR spectroscopy. The Li diffusivity turned out to be strongly correlated with the different grain boundary microstructures of the two nanocrystalline samples and with the degree of disorder introduced during preparation, as seen especially by HRTEM and EXAFS. Although in both samples nanostructuring yields an enhancement of the Li diffusivity compared to that in coarse grained LiNbO3, the Li diffusivity in ball milled LiNbO3 is much higher than in chemically prepared nanocrystalline LiNbO3. The former LiNbO3 sample has a large volume fraction of highly disordered interfacial regions which seem to be responsible for fast Li diffusion and to have a structure very similar to that of the amorphous form. This is in contrast to the chemically prepared sample where these regions have a smaller volume fraction.