Entwicklung und Charakterisierung von Siliziumnitrid-/Siliziumkarbidkompositen für den Einsatz in tribologisch hochbeanspruchten Gleitsystemen

Im Rahmen dieser Arbeit werden Siliziumnitrid–/Siliziumkarbidkompositwerkstoffe für tribologisch hochbeanspruchte Anwendungen entwickelt und charakterisiert. Bei der Charakterisierung der Kompositwerkstoffe wird der Zusammenhang zwischen dem Siliziumkarbidgehalt und der entstehenden Mikrostruktur sowie den mechanischen Eigenschaften dargestellt. Tribologisch wurden die Werkstoffe in Modellversuchen untersucht. Dabei zeigten sie ein sehr gutes Reib- und Verschleißverhalten

Error sources and geometry effects in DCDC-tests

The main advantages of DCDC-specimens are the completely stable crack extension after spontaneous crack initiation due to the decreasing stress intensity factor with increasing crack length and a very high path stability due to the strongly negative T-stress term. In this report, several possible error sources occurring in DCDC-tests are addressed: end effects in short specimens, differently long cracks at both sides of the drill hole, slight offset of the hole and the crack, non-symmetrical loading

Imitation in Large Games

In games with a large number of players where players may have overlapping objectives, the analysis of stable outcomes typically depends on player types. A special case is when a large part of the player population consists of imitation types: that of players who imitate choice of other (optimizing) types. Game theorists typically study the evolution of such games in dynamical systems with imitation rules. In the setting of games of infinite duration on finite graphs with preference orderings on outcomes for player types, we explore the possibility of imitation as a viable strategy. In our setup, the optimising players play bounded memory strategies and the imitators play according to specifications given by automata. We present algorithmic results on the eventual survival of types

Effect of negative T-stress on R-curves for Si3N4-ceramics

The main advantages of DCDC-specimens, completely stable crack extension and very high path stability due to the strongly negative Tstress term call for an application in R-curve determination. In this report, it is studied whether the T-stress affects the R-curve of silicon nitride. For this purpose, we selected three Si3N4-ceramics, which showed very flat crack resistance curves in test with edge-notched 4-point bending specimens. These materials were tested with DCDC-specimens. In contrast to the bending tests, the crack resistance decreased clearly. This effect can be understood as a consequence of the T-stress term

Placement, survival and predator identity of Eurasian Curlew Numenius arquata nests on lowland grass-heath

Capsule: Within the UK’s largest lowland Eurasian Curlew Numenius arquata population, curlew preferentially nested on physically disturbed (treated) than undisturbed (control) grassland, and low nest survival rates were primarily attributable to predation by Red Fox Vulpes vulpes. Aims: To inform conservation interventions for Curlew within semi-natural lowland dry-grassland landscapes. Methods: Across a 3700 ha lowland dry-grassland landscape, over two years, effects of ground-disturbance management on Curlew nest placement (n = 41) were examined using generalized linear models controlling for vegetation strata. The effects of site and management on nest survival (n = 44) were also examined, controlling for lay date and year. Nest predator identity was investigated using temperature sensors (n = 28) and nest cameras (n = 10). Results: Curlews were five times more likely to nest on physically disturbed than undisturbed grassland. Nest survival (overall mean ± se = 0.24 ± 0.07) was not influenced by year or ground-disturbance but declined with lay date and differed markedly between the two sites, consistent with predator control. Predation accounted for 29/32 failed nests and was predominantly at night (17/23 cases where timing was known), consistent with mammalian predators. Cameras indicated Red Foxes to be the main predator (4/5 cases). Overall breeding productivity was 0.16 ± 0.01 (SE) chicks per nesting attempt. Conclusion: Curlew suffered from unsustainably high rates of nest predation primarily attributable to Red Foxes. A combination of perimeter fencing and lethal predator control appeared to improve nest success at one site. Ground-disturbance treatment could encourage nesting attempts in areas managed to minimize predator density

Grabbing the Bull by Both Horns: Bovine Ultralong CDR-H3 Paratopes Enable Engineering of ‘Almost Natural’ Common Light Chain Bispecific Antibodies Suitable For Effector Cell Redirection

A subset of antibodies found in cattle comprises ultralong CDR-H3 regions of up to 70 amino acids. Interestingly, this type of immunoglobulin usually pairs with the single germline VL gene, V30 that is typically very conserved in sequence. In this work, we have engineered ultralong CDR-H3 common light chain bispecific antibodies targeting Epidermal Growth Factor Receptor (EGFR) on tumor cells as well as Natural Cytotoxicity Receptor NKp30 on Natural Killer (NK) cells. Antigen-specific common light chain antibodies were isolated by yeast surface display by means of pairing CDR-H3 diversities following immunization with a single V30 light chain. After selection, EGFR-targeting paratopes as well as NKp30-specific binders were combined into common light chain bispecific antibodies by exploiting the strand-exchange engineered domain (SEED) technology for heavy chain heterodimerization. Biochemical characterization of resulting bispecifics revealed highly specific binding to the respective antigens as well as simultaneous binding to both targets. Most importantly, engineered cattle-derived bispecific common light chain molecules elicited potent NK cell redirection and consequently tumor cell lysis of EGFR-overexpressing cells as well as robust release of proinflammatory cytokine interferon-γ. Taken together, this data is giving clear evidence that bovine bispecific ultralong CDR-H3 common light chain antibodies are versatile for biotechnological applications

AI/ML combined with next-generation sequencing of VHH immune repertoires enables the rapid identification of de novo humanized and sequence-optimized single domain antibodies: a prospective case study

Introduction: In this study, we demonstrate the feasibility of yeast surface display (YSD) and nextgeneration sequencing (NGS) in combination with artificial intelligence and machine learning methods (AI/ML) for the identification of de novo humanized single domain antibodies (sdAbs) with favorable early developability profiles.Methods: The display library was derived from a novel approach, in which VHH-based CDR3 regions obtained from a llama (Lama glama), immunized against NKp46, were grafted onto a humanized VHH backbone library that was diversified in CDR1 and CDR2. Following NGS analysis of sequence pools from two rounds of fluorescence-activated cell sorting we focused on four sequence clusters based on NGS frequency and enrichment analysis as well as in silico developability assessment. For each cluster, long short-term memory (LSTM) based deep generative models were trained and used for the in silico sampling of new sequences. Sequences were subjected to sequence- and structure-based in silico developability assessment to select a set of less than 10 sequences per cluster for production.Results: As demonstrated by binding kinetics and early developability assessment, this procedure represents a general strategy for the rapid and efficient design of potent and automatically humanized sdAb hits from screening selections with favorable early developability profiles

MyD88-dependent, superoxide-initiated inflammation is necessary for flow-mediated inward remodeling of conduit arteries

Vascular remodeling normalizes abnormal hemodynamic stresses through structural changes affecting vessel size and wall thickness. We investigated the role of inflammation in flow-mediated vascular remodeling using a murine model of partial outflow reduction without flow cessation or neointima formation. Common carotid arteries decreased in size after ipsilateral external carotid artery ligation in wild-type mice, but not in myeloid differentiation protein-88 (MyD88)–deficient mice. Inward remodeling was associated with MyD88-dependent and superoxide-initiated cytokine and chemokine production, as well as transient adventitial macrophage accumulation and activation. Macrophage depletion prevented flow-mediated inward vascular remodeling. Expression of MyD88 by intrinsic vascular cells was necessary for cytokine and chemokine production and changes in vessel size, whereas MyD88 expression by bone marrow–derived cells was obligatory for changes in vessel size. We conclude that there are at least two distinct roles for MyD88 in flow-mediated inward remodeling of conduit arteries. Our findings suggest that inflammation is necessary for vascular adaptation to changes in hemodynamic forces

Peroxiredoxin 3 Is a Redox-Dependent Target of Thiostrepton in Malignant Mesothelioma Cells

Thiostrepton (TS) is a thiazole antibiotic that inhibits expression of FOXM1, an oncogenic transcription factor required for cell cycle progression and resistance to oncogene-induced oxidative stress. The mechanism of action of TS is unclear and strategies that enhance TS activity will improve its therapeutic potential. Analysis of human tumor specimens showed FOXM1 is broadly expressed in malignant mesothelioma (MM), an intractable tumor associated with asbestos exposure. The mechanism of action of TS was investigated in a cell culture model of human MM. As for other tumor cell types, TS inhibited expression of FOXM1 in MM cells in a dose-dependent manner. Suppression of FOXM1 expression and coincidental activation of ERK1/2 by TS were abrogated by pre-incubation of cells with the antioxidant N-acetyl-L-cysteine (NAC), indicating its mechanism of action in MM cells is redox-dependent. Examination of the mitochondrial thioredoxin reductase 2 (TR2)-thioredoxin 2 (TRX2)-peroxiredoxin 3 (PRX3) antioxidant network revealed that TS modifies the electrophoretic mobility of PRX3. Incubation of recombinant human PRX3 with TS in vitro also resulted in PRX3 with altered electrophoretic mobility. The cellular and recombinant species of modified PRX3 were resistant to dithiothreitol and SDS and suppressed by NAC, indicating that TS covalently adducts cysteine residues in PRX3. Reduction of endogenous mitochondrial TRX2 levels by the cationic triphenylmethane gentian violet (GV) promoted modification of PRX3 by TS and significantly enhanced its cytotoxic activity. Our results indicate TS covalently adducts PRX3, thereby disabling a major mitochondrial antioxidant network that counters chronic mitochondrial oxidative stress. Redox-active compounds like GV that modify the TR2/TRX2 network may significantly enhance the efficacy of TS, thereby providing a combinatorial approach for exploiting redox-dependent perturbations in mitochondrial function as a therapeutic approach in mesothelioma