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A Soluble Expression Construct of the Isolated Catalytic Domain of Plasmodium falciparum ATP4 Exhibits ATPase Activity Independent of a γ-Phosphate Receiving Aspartate
Get PDFThe sodium/proton-exchanging ATPase of Plasmodium falciparum malaria parasites, PfATP4, is an emerging drug target. Inhibition results in detrimental cell swelling due to cytosolic accumulation of sodium and alkalization. PfATP4 is a sodium-releasing type II P-type ATPase restricted to apicomplexan parasites. Experimental data on structure-function relationships of the isolated protein are absent. Here, we produced and purified the soluble catalytic domain of PfATP4 and evaluated kinetic properties by in vitro phosphate colorimetry. The protein exhibited Mg2+-dependent ATPase activity at the same order of magnitude as the native cellular PfATP4 and was insensitive to the presence of sodium. AlphaFold 3-based structure and ATP/Mg2+ interaction predictions identified key residues of the nucleotide binding domain (Lys619, Lys652, Arg703). Replacement of the lysines by methionine decreased the enzymatic activity to one quarter. Individual mutation of the putative Mg2+-coordinating Asp865 of the phosphorylation domain was tolerated, while a joint replacement with Asp869 decreased ATPase again to one quarter. Mutation of the putative γ-phosphate receiving Asp451 maintained the rate of Pi release. Our data attribute typical functional roles for P-type ATPases to the basic and acidic residues of the soluble PfATP4 catalytic domain and show that its ATP hydrolysis is independent of phosphorylation of Asp451
Role of the Setae in an Ectoparasitic Seal Louse in Reducing Surface Drag: Numerical Modeling Approach
Get PDFEchinophthirius horridus, an ectoparasitic seal louse adapted for living on diving wildlife in the marine environment, exhibits unique cuticular morphology with dense body coverage of characteristically-shaped setae. This study investigates their potential role in reducing drag during the host's diving activities. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) examines E. horridus setae morphology, revealing stair-like elevations and gradual sclerotization increase from base to tip. Numerical simulations using movable cellular automata (MCA) demonstrate that optimal inclination of surface protrusions leads to vortex formation, potentially reducing friction and energy losses. Vertical protrusions cause stronger flow perturbations and higher energy dissipation compared to natural inclination. Over time, as flow self-organizes, total power losses decrease, suggesting natural selection optimized surface structure inclination and spacing to minimize friction and energy losses. Comparisons with shark scales reveal morphological similarities but different drag reduction mechanisms, with seal louse setae utilizing a “ball-bearing” effect and shark scales relying on a “riblet effect.” This study provides insights into surface topography's influence on fluid dynamics at small scales, with potential applications in understanding biological surfaces and designing reduced surface drag artificial surfaces
Phase behavior of silica-PNIPAm nanogels under high hydrostatic pressure
Get PDFThe structure and dynamics of concentrated silica-PNIPAm (poly-N-iso-prop-yl-acrylamide) nanogels are studied as a function of hydrostatic pressure up to 3500 bar. A combination of X-ray photon correlation spectroscopy and small-angle X-ray scattering shows similar characteristics of the dynamics for both temperature- and pressure-induced volume phase transitions of PNIPAm nanogels. Upon increasing the pressure and depending on the initial particle volume fraction, a transition from a liquid or glass state to a colloidal gel is observed for pressures p ≃ 1500 bar at a temperature of 293 K. Time-dependent analysis of the dynamics shows aging in glass and gel samples which is absent in the liquid state. This indicates stress-dominated dynamics upon pressure changes that equilibrate after a few hundred seconds
Political Liberation, Hope, and Social Competition Are the Motor of Secular Trends in Height
Get PDFBackground Long-term improvements in physical living conditions correlate with long-term trends in height. Aim To link temporal characteristics of the secular trend in height with the simultaneous political and economic dynamics. Sample and methods Height of men of the German Armed Forces born between 1865 and 1975 was correlated with indicators of economic prosperity (GDP), nutrition and health (infant mortality), and indicators of social inhomogeneity (income inequality and household wealth share). The time periods before 1916, between 1916 and 1933, 1947, 1973, and after 1989 were separately analyzed. Coherence analysis was used to assess the changes in the temporal trends. Results Mean height of young adult men increased by 0.45 mm/year (before 1916), by 2.15 mm/year (1916-1933), by 1.87 mm/year in the early Federal Republic of Germany (FRG) until 1973, by 1.45 mm/year in the late FRG, and by 4 mm/year in East German conscripts after the reunification in 1989. The most substantial height increments occurred in periods of political upheaval and loss of state authority. Conclusion The nonlinear pattern of secular height increments in Germany since the late 19th century suggests that political liberation, hope for a better life, and illusions of equity, freedom, justice, and the expectation of social advancement are associated with competitive growth, strategic growth adjustments, and finally, long-term and substantial secular trends in height
Additive engineering mechanisms in antimony chalcogenide solar cells: a focus on deeper understanding
Get PDFAntimony chalcogenides represent a promising thin-film solar cell technology, offering inherently high stability, composed of elements more abundant than those used in established technologies such as CIGS and CdTe, and with the potential to approach the Shockley–Queisser efficiency limit of ∼33%. However, the current efficiencies are low compared to the market leader, silicon, at around 10%. Chemical additives have been employed to achieve this efficiency, and many research groups believe they are key to achieving even higher efficiencies. However, to achieve that a keen focus on the mechanisms underlying the improvements gained from these additives is necessary, so upcoming research can build upon that prior work and more widely applicable knowledge in the field can be gained. In this article, we highlight some examples where the explanation/exploration of the mechanisms is done to an excellent degree. We hope that by highlighting these examples, steps will be taken towards more mechanism-focussed studies, which will yield more knowledge of the systems and behaviours present in antimony chalcogenide solar cells and the additives used to improve them
Intrinsic and Extrinsic Modifications of Titanium Dioxide Based Photocatalytic Nanomaterials
Get PDFThis thesis focuses on TiO2 based nanomaterials with various intrinsic and extrinsic modifications for photocatalysis. The expansion of industrialization causes energy problems and negative effects on the environment. Therefore, experts call for sustainable solutions. By utilizing light, photocatalysis offers potrntial sustainable method for facilitating chemical reactions. TiO2 itself is a promising photocatalyst. However, it suffers from two drawbacks which are low visible light absorption and fast recombination. Nanoscale materials offer a pathway to mitigate these drawbacks. In this regard, this thesis explores nanoscale modifications of TiO2 based photocatalysts. First, an extrinsic modification by a combination of TiO2 nanoparticles in a composite lead to increases in photocatalytic activity. Here, TiO2 nanoparticles fabricated with a Haberland type gas aggregation cluster source were combined with Ag nanoparticles as well as a ZnO thin film. Furthermore, the intrinsic modification via defects in TiO2 was explored by subjecting photocatalytic TiO2 with H2 and Ar gas. Here, an increase in photocatalytic performance was observed when combining H2 and Ar. Analysis indicated that Ar likely has an influence on the defective structure which in turn influences the photocatalytic activity. Additionally, the thesis explored the method of nanoparticles fabricated via gas aggregation. Here, TiOx-CeOx heterostructure nanoparticles were produced by combining a gas aggregation cluster source with segmented Ti/Ce targets. Lastly, the combination of intrinsic and extrinsic modifications was explored by fabricating a composite containing a defective TiO2 thin film obtained from hydrogenation and an organic top layer
Beiträge zur XVII. Internationalen Slavistischen Konferenz
Get PDFDie Junge Slavistik im Dialog ist eine Konferenzreihe an der Universität Kiel, die sich vorwiegend an Studierende und Promovierende der Slavistik und benachbarter Fächer richtet. Eine Auswahl der Beiträge wird jedes Jahr in einem Sammelband im Open Access veröffentlicht. Im vorliegenden Band erscheinen 19 deutsch- und englischsprachige Beiträge zu unterschiedlichen Themen rund um die Slavia: Von sprachlichen Strukturen des Protopopen Avvakum über historische Verflechtungen des sächsischen und polnischen Militärs sowie das tschechische absurde Theater bis hin zu digitalen Korpora und Reflexionen über Zugehörigkeit und interkulturelle Kompetenzen.Junge Slavistik im Dialog (Young Slavistics in Dialogue) is a conference series held at Kiel University, primarily aimed at students and doctoral candidates in Slavic Studies and related disciplines. Each year, a selection of the contributions is published in an open-access edited volume. The present volume features 19 contributions in German and English, covering a wide range of topics related to the Slavic world: from the linguistic structures of Archpriest Avvakum to historical entanglements between the Saxon and Polish military, Czech absurdist theatre, digital corpora, and reflections on belonging and intercultural competencies
Der diskrete Charme des Vergangenen: Michal Vieweghs Familienroman Báječná léta pod psa (1992)
Get PDFDer Beitrag widmet sich dem Roman Báječná léta pod psa (1992) des tschechischen Autors Michal Viewegh, der als Beispiel für neue Tendenzen in der tschechischen Erinnerungsliteratur nach 1989 gilt. Im Mittelpunkt steht die Frage, wie Viewegh das klassische Genre des Familienromans nutzt, um die Verflechtung von »großer« und »privater« Geschichte in der Tschechoslowakei während der Normalisierung zu thematisieren. Es wird gezeigt, dass Báječná léta pod psa das Leben der Familie des Protagonisten Kvido im Spätsozialismus auf ironische Weise darstellt, wodurch die politische Tragödie des Landes entschärft wird. Im Prozess der nostalgischen Erinnerung wird deutlich, dass die politische Geschichte zwar großen Einfluss auf das Familienleben ausübte, aber dennoch Raum für eine gewisse Souveränität ließ. Die Normalisierung veränderte das Leben von Kvido und seiner Familie von Grund auf, machte ihn aber auch zu einem reflektierten Schriftsteller. Diese Ambivalenzen werden im Roman anhand des Hundemotivs diskutiert.The article is dedicated to the novel Báječná léta pod psa (1992) by the Czech author Michal Viewegh, which is considered an example of new tendencies in Czech memoir literature after 1989. The focus is on the question of how Viewegh uses the classic genre of the family novel to address the interweaving of »big« and »private« history in Czechoslovakia during normalisation. It is shown that Báječná léta pod psa depicts the life of the protagonist Kvido's family in late socialism in an ironic way, thereby defusing the political tragedy of the country. In the process of nostalgic remembrance, it becomes clear that although political history exerted a great influence on family life, it still left room for a certain sovereignty. Normalisation fundamentally changed the lives of Kvido and his family, but also made him a reflective writer. These ambivalences are discussed in the novel using the dog motif
Experimental Evolution in Pseudomonas Fluorescens Cell Division and Protein Translation
Get PDFIn this thesis, I investigate the evolution of cell wall synthesis and protein translation in Pseudomonas. The experiments show how evolution shape both processes, and the organism can alter different cellular systems as and adaptive answer to their disruption. In the first chapter, disruption of longitudianl cell wall elongation leads to defect in cell division, recoverable thorugh mutations of the cell division system. In the second and third chapter, loss of ribosomal proteins leads to lowered fitness due to a decrease in protein synthesis, recoverable trough furhter changes in transcription regulation
Impacts of Out-Grower Schemes, Technology Adoption, and Market Participation on Smallholder Household Welfare in Northern Ghana
Get PDFSmallholder farmers in developing countries like Ghana face significant challenges, including low productivity, limited access to inputs and markets, and financial constraints, which contribute to persistent poverty and food insecurity. Outgrower schemes have emerged as a viable solution by integrating smallholders into structured value chains, offering them input-based credit, training, and assured markets. This study examines the determinants and impacts of outgrower scheme participation, collective market engagement, in-kind credit access, and market orientation on farm performance and household welfare. Using advanced econometric models—including endogenous treatment effects, multinomial endogenous switching regression, marginal treatment effects (MTE), and ordered probit selection—the study finds that participants in outgrower schemes use more inorganic fertilizer and weedicide and achieve higher maize yields than nonparticipants, with regional variations. Collective participation in both input and output markets significantly enhances commercialization, farm income, and household consumption. Access to in-kind credit improves dietary diversity, reduces poverty and food insecurity, and increasing access through shorter distances encourages more participation. Furthermore, transitioning from subsistence to surplus or commercial market orientations yields better income and food security outcomes. The study underscores the importance of institutional support, public-private partnerships, and targeted policies to facilitate smallholder access to agricultural inputs, output markets, and financial services, thereby promoting inclusive agricultural growth and aligning with Sustainable Development Goals