Willkommen bei JLUpub
JLUpub ist das institutionelle Repositorium der Justus-Liebig-Universität.
JLUpub bietet Mitgliedern und Angehörigen der Universität die Möglichkeit neben wissenschaftlichen Dokumenten auch Forschungsdaten elektronisch zu veröffentlichen und dauerhaft zugänglich zu machen. Alle Veröffentlichungen erhalten einen Digital Object Identifier (DOI) und werden über nationale und internationale Bibliothekskataloge sowie Suchmaschinen nachgewiesen und auffindbar.
Neue Veröffentlichungen:
Item type: Item , Einfluss inflammatorischer Stimuli auf das kardiomyozytäre Differenzierungspotential mesenchymaler Stammzellen(2024) Hellwig, YuliyaThe results of this project show that an inflammatory environment impairs the cardiac differentiation of stem cells. The meta-analyses show that stem cell therapies significantly reduce mortality and improve LVEF moderately, but significantly. However, the effect that was hoped for, namely the regeneration of infarcted tissue, does not materialize. The results of this study show that the inflammatory environment prevailing after a heart attack has a negative effect on the cardiac differentiation of stem cells. Modulation of the inflammatory niche could improve the cardiac differentiation rate of stem cells and thus achieve regeneration of the damaged myocardium. Further studies could focus on identifying factors that interfere with cardiac differentiation more precisely. Another starting point for research could be the modulation of inflammation, which would lead to better differentiation of the injected stem cells.Item type: Item , Land access and feeding strategies in post-Soviet livestock husbandry: Evidence from a rangeland system in Kazakhstan(2024) Robinson, Sarah; Petrick, MartinContext: Feeding strategy is a major dimension of intensification and largely determines the environmental and economic impacts of livestock production systems, in particular concerning land use competition, greenhouse gas emissions and rural livelihoods. Literature suggests that a key driver of intensification is increasing population density – associated with decreased labor costs, shifts in demand and institutional and political change; whilst at the household level farmer education and market access are also important. However, the topic has not been addressed in the rangelands of post-Soviet Eurasia, where vast underused pasture resources may be reclaimed, but improved feeding is also a key aim of agricultural policy. Objectives: We aim to firstly describe the extent to which land users in an extensive rangeland system in Kazakhstan exploit pastures, arable land or markets to feed their animals, and secondly to explore the determinants of these decisions. Methods: We identify three potential strategies: self-production of roughage or concentrate, purchase of these inputs, or expansion of pasture use through mobile pastoralism. We then investigate the determinants of these feeding strategies and their interactions, including variables capturing farm and farmer characteristics, access to land and other assets and outcomes of post-independence reforms. We examine the factors determining the three feeding strategies using a farm survey dataset from south-eastern Kazakhstan to estimate a simultaneous equation system, considering herd size as an endogenous variable. Results and Conclusions: Herd size combined with access to land for fodder production largely determines how producers feed their livestock. Barriers to the substitution of pasture for purchased or self-produced fodder include cropland access, distance from markets, and credit availability, so that use of remote and seasonal pastures is the major feeding strategy employed by larger producers. Access to both arable land and pasture is dependent on land reform outcomes, which constrain farmers' livestock feeding decisions today. Other factors such as farmer education, human population density and household labor are less important. Significance: Grazing expansion strategies employed by farmers studied here differ from those based on external input use observed in many regions of the world. Instead, they reflect the continuing importance of pastoral resources in rangeland environments implying important trade-offs to intensification which merit further study.Item type: Item , Mid- to long-term periprosthetic bone density changes after cementless short stem hip arthroplasty in elderly: A clinical and radiological analysis(2024) Brandl, Max; Jahnke, Alexander; Fölsch, Christian; Rickert, Markus; Ishaque, Bernd AlexanderIntroduction: Short stem prostheses were originally designed for younger and more active patients. In recent years, they have been increasingly offered to older patients. This study evaluates the mid-to long-term survival of a short stem prosthesis and the changes in periprosthetic bone density following implantation of a cementless short hip stem in patients over 60 years of age. Methods: 118 patients aged over 60 received short stem prostheses. Clinical examination included Harris Hip Score (HHS) and Hip Disability and Osteoarthritis Outcome Score (HOOS). 93 patients were followed clinically for at least five years. 53 patients underwent dual-energy x-ray absorptiometry (DXA) and radiographic evaluation. Follow-up intervals were preoperative and postoperative (t0), at approximately six months (t1), at approximately two years (t2), and at approximately five years or later (t3). Results: Over a mean 6.7-year observation period for all 118 patients, one stem revision occurred due to a traumatic periprosthetic stem fracture. The five-year survival rate for the endpoint survival of the Metha® stem in 95 at-risk patients is 99.2%. HHS improved significantly from t0 55.3 ± 11.5 (range 30–79) to t3 95.3 ± 8.6 (range 57–100) at a mean of 8.0 years (p < 0.001). HOOS improved significantly in each subscale (p < 0.001). Bone mineral density (BMD) was available for review in 53 patients after a mean of 7.1 years. BMD increased from t0 to t3 in region of interest (ROI) 3 (+0.4%) and ROI 6 (+2.9%) and decreased in ROI 1 (−10.3%), ROI 2 (−9.8%), ROI 4 (−5.3%), ROI 5 (−3.4%) and ROI 7 (−23.1%). Conclusions: The evaluated short stem prosthesis shows a remarkably high survival rate in elderly patients, accompanied by excellent clinical results. Load transfer measurements show a metaphyseal-diaphyseal pattern with a trend towards increased diaphyseal transfer over the period observed.Item type: Item , Impact of earthworms on soil Si availability and wheat Si concentration in low- and high-Si soils(2024) Monoshyn, Dmytro; Chibesa, Mirriam C.; Puschenreiter, Markus; Zaller, Johann G.; Santner, JakobSilicon (Si) is a beneficial element known to increase growth and the stress resistance of plants, including resistance against drought. However, as with many other elements, only a small fraction of Si in soils is available for plant uptake. Plant-available Si originates either from the weathering of soil minerals or from the dissolution of phytoliths in plant litter. It is known that soil fauna plays a role in both processes that contribute to the availability of Si in the soil. However, very little is known about the interactions between the weathering of soil minerals and the dissolution of Si by earthworms from phytoliths and subsequent Si uptake by plants. In greenhouse pot experiments, this study investigated the effect of an epigeic earthworm species (Dendrobaena veneta) on Si availability and uptake by wheat (Triticum aestivum) grown in soils with high or low Si availability. In addition, Si-rich plant litter (wheat straw) was added to the topsoil in some treatments. The addition of plant litter significantly increased the available Si in the soil. Plant litter addition was positively correlated with the Si concentration in wheat in low-Si soil, but not in high-Si soil. Earthworms increased Si availability in soil and casts of the low-Si soil and partly of the high-Si soil, but not Si uptake by wheat. These results suggest that earthworms play an important role in regulating the Si status of soils and may influence Si uptake by plants, especially in soils with initially low Si content and when earthworm population densities are high.Item type: Item , Impedance spectroscopy using microscopic reference electrodes to analyze different rate-determining steps in aqueous dye-sensitized solar cells using nitroxide radicals as redox mediators(2024) Holzhacker, Daniel; Ringleb, Andreas; Schlettwein, DerckFor new components in dye-sensitized solar cells (DSSCs), identification and quantification of rate-limiting steps is needed to evaluate their applicability. This is particularly important if fundamental changes are studied. In this work, the use of a micro-reference electrode in DSSCs is proposed to increase the significance of electrochemical impedance spectroscopy. The recombination of charge carriers at the photoanode and the regeneration of redox mediators at the counter electrode, which typically occur on similar timescales, could be studied separately but simultaneously in cells under operating conditions. This is particularly useful in the study of water-based DSSCs. Here, cells with 2,2,6,6-Tetramethylpiperidinoxyl (TEMPO) or 4-Hydroxy-TEMPO (OH-TEMPO) as redox mediators using additives like 1-Methylbenzimidazole (MBI) are discussed. It was revealed that the charge transfer resistance (RCE) for the reduction of the oxidized redox mediator at the counter electrode (CE) limits the fill factor (FF) of such DSSCs. TEMPO/MBI electrolytes yielded low RCE and high FF, whereas OH-TEMPO in otherwise identical cells resulted in large RCE, low FF, and low conversion efficiencies. This indicates that the interface between the CE and the electrolyte significantly influences the DSSC performance of these cells and strongly depends on the electrolyte composition. Important optimization strategies could be discussed based on the present results.