Diffusion in Nanoporous Materials: Novel Insights by Combining MAS and PFG NMR

Pulsed field gradient (PFG) nuclear magnetic resonance (NMR) allows recording of molecular diffusion paths (notably, the probability distribution of molecular displacements over typically micrometers, covered during an observation time of typically milliseconds) and has thus proven to serve as a most versatile means for the in-depth study of mass transfer in complex materials. This is particularly true with nanoporous host materials, where PFG NMR enabled the first direct measurement of intracrystalline diffusivities of guest molecules. Spatial resolution, i.e., the minimum diffusion path length experimentally observable, is limited by the time interval over which the pulsed field gradients may be applied. In “conventional” PFG NMR measurements, this time interval is determined by a characteristic quantity of the host-guest system under study, the so-called transverse nuclear magnetic relaxation time. This leads, notably when considering systems with low molecular mobilities, to severe restrictions in the applicability of PFG NMR. These restrictions may partially be released by performing PFG NMR measurements in combination with “magic-angle spinning” (MAS) of the NMR sample tube. The present review introduces the fundamentals of this technique and illustrates, via a number of recent cases, the gain in information thus attainable. Examples include diffusion measurements with nanoporous host-guest systems of low intrinsic mobility and selective diffusion measurement in multicomponent systems

Chemical Heterogeneities along the South Atlantic Mid-Ocean-Ridge (5-11°S): Shallow or Deep Recycling of Ocean Crust?

Between 5° and 11°S, the Mid-Atlantic Ridge displays anomalous crustal thickness and geochemical compositions, thought to be related to either small scale upper mantle heterogeneities or a weak, diffuse mantle plume. We report new high precision trace element and Sr, Nd and Pb (DS) isotope data for 72 ridge axis samples and 9 off-axis seamount samples along with U–Th–Ra disequilibria data for off axis seamounts at c. 9.7°S. At least four distinct components are needed to explain the geochemical variations along the ridge: 1) a common depleted (D-MORB-like) component near and north of 4.8–7.6°S, 2) an enriched component upwelling beneath Ascension Island and the northern A1 ridge segment (segment numbers ascend from north to south), 3) an enriched component upwelling beneath the A2 ridge segment, and 4) an enriched component upwelling beneath the line of seamounts east of the A3 segment and the A3 and A4 segments. The A1 and the A3+A4 segment lavas form well-defined mixing arrays from Ascension Island and the A3 seamounts respectively to the depleted D-MORB component. We propose that the enriched components represent different packages of subducted ocean crust and/or ocean island basalt (OIB) type volcanic islands and seamounts that have either been recycled through 1) the shallow mantle, upwelling passively beneath the ridge system or 2) the deep mantle via an actively upwelling heterogeneous mantle plume that interacts with the ridge system

Leipzig’s Inner East as an Arrival Space? Exploring the Trajectory of a Diversifying Neighbourhood

The article analyses and discusses the development of Leipzig and especially its inner east as an ‘urban space of arrival’ since 1990. It represents a study about arrival in the post-socialist context that is fairly rare in the international debate so far, since most of the arrival debate builds on western European evidence. Leipzig’s inner east was characterised by shrinkage until the end of the 1990s and by new growth, especially after 2010, as the whole city grew. Since the second half of the 1990s the inner east has developed into a migrant area, referred to here as an ‘arrival space.’ Today, in 2020, it represents the most heterogeneous part of the city in terms of population structure and is one of the most dynamic areas in terms of in- and out-migration. At the same time, it represents an area where large amounts of the population face different types of disadvantage. Set against this context, the article embeds the story of Leipzig’s inner east into the arrival debate and investigates the area’s development according to the characteristics discussed by the debate. Our results reveal that Leipzig’s inner east represents a meaningful example of an arrival space in a specific (post-socialist, shrinkage followed by regrowth) context and that arrival and its spatial allocation strongly depend on factors like population, housing, and real estate market development, as well as policymaking and, significantly, recognition

Sortenprüfung frühabreifender Sojabohnensorten im ökologischen Landbau

Um das Wachstumspotential von Sojabohnen (Glycine max (L.)) im ökologischen Anbau und unter ungünstigen klimatischen Bedingungen zu testen wurden an zwei Standorten (University of Applied Sciences, Waldhof) and Frankenhausen (University of Kassel, Hessian State Farm Frankenhausen)Feldversuche mit sechs unterschiedlichen Sojabohnensorten durchgeführt.Erfasst wurden das Pflanzenwachstum, phänologische Stadien, Ertrag, Rohprotein und Tausendkorngewicht. Einige der getestetem Sorten zeigten vielversprechende Ergebnisse in Bezug auf den Ertrag und die Quälität. Zur Absicherung der Ergebnisse werden weitere Versuche in 2010 durchgeführt

The turnover number for band 3-mediated sulfate transport in phosphatidylcholine bilayers

AbstractThe anion transport system of the human erythrocyte membrane was reconstituted in unilamellar phosphatidylcholine vesicles, and a vesicle subpopulation of a narrow size distribution was isolated from the sample by gel filtration. In this subpopulation, the turnover number of the transport protein (the band 3 protein) for sulfate transport was determined. It was found that, in the reconstituted system, the protein transports sulfate 5–10-times faster than in the human erythrocyte membrane

Untersuchungen zur Winterhärte von Wintererbsen

Winter peas have several agronomic advantages in comparison to spring pea, but the overwintering of winter peas are uncertain under the climatic conditions in Germany. Therefore, the winterhardiness of four genotypes (cvs. Assas, Cheyenne, EFB 33, Württembergische) was examined in two field trials in three growing seasons. In a first trial all peas were grown in pure and mixed stands with rye at the experimental farm of the University of Kassel and at the experimental farm of the University of Applied Sci-ence in Osnabrueck. In a second trial the impact of three sowing dates (mid of Sep-tember, end of September/begin of October and mid of October, respectively) was de-termined at the experimental farm of the University of Kassel only in pure stands. In contrast to Assas and Cheyenne, EFB 33 and Wuerttembergische always showed sufficient winter hardiness in both trials. Consequently, a rosette growth with small leaves and short internodes at the onset of winter as well as a quantitative photoperi-odic sensitivity is required for high winter survival under the climatic conditions in Germany. Furthermore the risk of winterkill for winter peas was higher at the experi-mental site in Osnabrueck than in Kassel in two of three growing seasons due to less snow blanket in one winter and because of waterlogging as a consequence of sandy soil and unusual high precipitation in the other winter, respectively

The Local Governance of Arrival in Leipzig: Housing of Asylum-Seeking Persons as a Contested Field

The article examines how the German city of Leipzig governs the housing of asylum seekers. Leipzig was a frontrunner in organizing the decentralized accommodation of asylum seekers when adopting its accommodation concept in 2012. This concept aimed at integrating asylum-seeking persons in the regular housing market at an early stage of arrival. However, since then, the city of Leipzig faces more and more challenges in implementing the concept. This is particularly due to the increasingly tight situation on the housing market while the number of people seeking protection increased and partly due to discriminating and xenophobic attitudes on the side of house owners and managers. Therefore, we argue that the so-called refugee crisis of 2015–2016 has to be seen in close interaction with a growing general housing shortage in Leipzig like in many other large European cities. Furthermore, we understand the municipal governing of housing as a contested field regarding its entanglement of diverse federal levels and policy scales, the diversity of stakeholders involved, and its dynamic change over the last years. We analyze this contested field set against the current context of arrival and dynamic urban growth on a local level. Based on empirical qualitative research that was conducted by us in 2016, Leipzig’s local specifics will be investigated under the umbrella of our conceptual framework of Governance of Arrival. The issues of a strained housing market and the integration of asylum seekers in it do not apply only to Leipzig, but shed light on similar developments in other European Cities

The (co-)production of arrival neighbourhoods. Processes governing housing markets in three german cities

In recent years, an emerging strand of research has focused on the role arrival neighbourhoods play for newcomers finding their footing in a new urban context. However, little is known about the underlying factors and drivers influencing their function(ing). This concerns in particular the role of the local housing market and its players in shaping their emergence and development. The paper deals with the question of how arrival neighbourhoods are (co-)produced by housing market players and how the latter are embedded in local governance structures. Looking at three German arrival neighbourhoods, the article illustrates how they are co-produced by ownership structures and the allocation practices of different housing market players. However, the strengthening of an arrival neighbourhood´s function not only depends on ownership structures but also on the capacities of municipal housing providers and civil society organisations, their strategic goals and the will for (concerted) action. Our findings show that arrival neighbourhoods can take on an important citywide function, enabling newcomers to gain a foothold in the city if three criteria are met: they are accessible/affordable for low-income groups, are equipped with infrastructures for newcomers, and are permeable with regard to residents’ relocation to other neighbourhoods