Technische Universität Dresden: Qucosa
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Quasi-static shock absorber friction at low velocity reciprocating sliding conditions
No full textThe characteristics of vehicle shock absorbers have a major significance regarding vehicle dynamics, thus affecting vehicle ride comfort, handling and safety. Although much research focuses particularly on the hydraulic damping properties of this vital suspension component, friction properties are not considered in great detail. However, for driving scenarios of low excitation and velocity of the shock absorber due to moderate roughness of the road, the friction force generated by the shock absorbers and the remaining components is particularly important regarding the transfer of vibration from the road to the passenger. Hence, this study investigates the sensitivity of shock absorber friction to various parameters in the quasi-static domain. The effects of side force, temperature, excitation amplitude and waveform are determined for multiple shock absorbers. The results show no significant influence of the amplitude and waveform used in the conducted tests. Contrarily, the friction force strongly depends on the side force, which represents the variable load perpendicular to the shock absorber’s main axis arising during various driving events for MacPherson suspensions. An increased temperature reduces the side force effect
Fatigue Phase-field Modeling for Elastomeric Materials
No full textFatigue failure prediction of elastomeric materials plays a crucial role in engineering applications, e.g., rolling tires. Experimental investigations, as a straightforward evaluation of fatigue failure, do not enable an efficient insight due to significant time consumption. Therefore, several numerical approaches are developed to model fatigue fracture or damage behavior of material components subjected to cyclic loading. Inspired by [1], the work at hand incorporates a degrading fracture toughness into a promising phase-field method. As a smeared crack representation, the phase-field model does not depend upon any explicit criterion for crack evolution, e.g., crack initiation and propagation. Furthermore, this work proposes a novel algorithm, which is based on a post-processing technique, to evaluate the energy release rate for PARIS' parameters during the stable crack propagation regime. The methodology is implemented into the Finite Element framework and a demonstrative numerical example is simulated
Meso-scale thermo-magneto-mechanical constitutive model for magneto-active elastomers
No full textMagneto-active elastomers (MAE) are one of many emerging smart materials. They have applications in mechanical, civil and biomedical engineering as actuators, such as grippers, and dampers, such as tunable vibration absorbers. MAE consist of a soft polymeric matrix filled with micron-sized magnetizable particles. Set in a magnetic field, the particles displace, stiffening the entire composite by up to three orders of magnitude.
The literature contains myriad purely magneto-mechanical models for MAE. This contribution introduces a thermal component to enable prediction of heat generation in the composite due to oscillatory, visco-elastic mechanical deformations. This model, formulated for three-dimensional finite deformations, is capable of accurately modeling the behavior of incompressible materials through a Q1P0 finite element framework. Numerical simulations qualitatively show the capabilities of this model to describe the fully-coupled thermo-magneto-mechanical response of MAE
Sciatic nerve injury regeneration in adult male rats using gelatin methacrylate (GelMA)/poly(2-ethy-2-oxazoline) (PEtOx) hydrogel containing 4-aminopyridine (4-AP)
No full textOne of the most important parts of the body is the peripheral nervous system, and any injuries in this system may result in potentially lethal consequences or severe side effects. The peripheral nervous system may not rehabilitate the harmed regions following disabling disorders, which reduce the quality of life of patients. Fortunately, in recent years, hydrogels have been proposed as exogenous alternatives to bridge damaged nerve stumps to create a useful microenvironment for advancing nerve recovery. However, hydrogel-based medicine in the therapy of peripheral nerve injury still needs a lot of improvement. In this study, GelMA/PEtOx hydrogel was used for the first time to deliver 4-Aminopyridine (4-AP) small molecules. 4-AP is a broad-spectrum potassium channel blocker, which has been demonstrated to increase neuromuscular function in patients with various demyelinating disorders. The prepared hydrogel showed a porosity of 92.2 ± 2.6% after 20 min, swelling ratio of 456.01 ± 2.0% after 180 min, weight loss of 81.7 ± 3.1% after 2 weeks, and good blood compatibility as well as sustainable drug release. MTT analysis was performed to assess the cell viability of the hydrogel and proved that the hydrogel is an appropriate substrate for the survival of cells. In vivo studies were performed for functional analysis and the sciatic functional index (SFI) as well as hot plate latency results showed that the use of GelMA/PEtOx+4-AP hydrogel enhances the regeneration compared to the GelMA/PEtOx hydrogel and the control group
Positive Ulrich sheaves
No full textWe provide a criterion for a coherent sheaf to be an Ulrich sheaf in terms of a certain bilinear form on its global sections. When working over the real numbers, we call it a positive Ulrich sheaf if this bilinear form is symmetric or Hermitian and positive-definite. In that case, our result provides a common theoretical framework for several results in real algebraic geometry concerning the existence of algebraic certificates for certain geometric properties. For instance, it implies Hilbert’s theorem on nonnegative ternary quartics, via the geometry of del Pezzo surfaces, and the solution of the Lax conjecture on plane hyperbolic curves due to Helton and Vinnikov
I can see how you feel—Methodological considerations and handling of Noldus's FaceReader software for emotion measurement
No full textThe human face provides countless pieces of information, not least through the display of emotions, driving intensified research interest. Common research methods, such as self-reports, often neglect the subtlety of unconscious emotional responses or risk distortion due to subjective evaluations. Although emotions can occur unconsciously, they sometimes trigger the smallest physiological changes in terms of muscle movements in the face. Manually associating specific emotions with such subtle changes proves to be both time-consuming and intricate. Facereader software, a tool that evaluates video recordings to categorize facial expressions based on muscle movements, including basic emotions, receives more attention, with Noldus' FaceReader software being a prominent example. Nevertheless, a comprehensive pre-purchase guide detailing potential use cases and operational prerequisites is conspicuously lacking, and insights into processing generated data outputs remain confined. Addressing this gap, this paper contributes preliminarily to creating an overview of the use and handling of Noldus FaceReader in different research areas so far. Our findings illuminate pivotal factors for experimental scenario decision-making, offering valuable guidance for methodological considerations involving FaceReader. Consequently, a proposed pioneering guideline aims at standardizing FaceReader utilization, fostering accurate data management, and nuanced result interpretation
Improving flushing processes through targeted control of the temperature boundary conditions
No full textIn this contribution the authors investigate how flushing of chocolate using a follow-up chocolate in a straight horizontal pipe is affected by temperature. The authors investigate a non-uniform distribution of temperature across the considered domain. This is done using two cases, where the first exhibits a wall temperature deviating from the normal process temperature and the second exhibits a differently tempered follow-up chocolate. The investigations are performed using unsteady three-dimensional numerical simulations with an OpenFOAM multiphase solver, which is extended to include an additional equation for energy conservation. The physical properties of the chocolate are analyzed with respect to their dependence on temperature and implemented in a new model in OpenFOAM. The results of both cases are assessed according to industrially relevant questions. Among others, they include the amount of follow-up chocolate needed to achieve a set goal of cleanliness. The time needed to achieve this is also considered. A dimensionless time is used to compare the different cases. Recommendations are provided on how different temperature of pipe wall and follow-up chocolate may lead to improved flushing processes and which savings may be achieved with this strategy
Effects of Behavioral Activation Group Treatment Prior to Individual Therapy for Depression
No full textGroup therapy has the potential to reach more people seeking treatment at the same time while achieving similar success rates as individual therapy. We examined whether adding group therapy (behavioral activation) before individual therapy shortens the duration of therapy while being no less effective than pure individual therapy. In a cognitive behavioral therapy (CBT) outpatient clinic, we analyzed data from N = 290 patients diagnosed with depression. While comparing group plus individual versus pure individual therapy, we controlled for systematic differences using propensity score matching. Patients receiving group therapy prior to individual therapy waited significantly shorter for treatment and needed fewer individual sessions. Linear mixed model analysis of depression scores revealed a significant interaction between time and condition, indicating that patients in the combination treatment improved faster than patients who received individual therapy only. Prior group treatment with behavioral activation increases the efficiency of outpatient CBT for depression.Gruppentherapie hat das Potential mehr Hilfesuchende zur gleichen Zeit zu erreichen und erzielt meist ähnliche Erfolgsraten wie die Einzeltherapie. Es wurde untersucht, inwieweit sich bei gleicher Wirksamkeit die Behandlungsdauer durch eine Teilnahme an einer vorgeschalteten Gruppentherapie verkürzt. In einer naturalistischen Studie wurden Daten von N = 290 depressiven Patient_innen analysiert. Angesichts der nicht-randomisierten Beobachtungsdaten kontrollierten wir systematische Unterschiede mit Hilfe von Propensity Score Matching. Die Wartezeit und die Dauer der Einzeltherapie konnte bei Patient_innen, die der Gruppenteilnahe zustimmten reduziert werden. Die Analyse des linearen gemischten Modells für die Depressionswerte ergab eine signifikante Interaktion zwischen Zeit und Gruppe, was darauf hindeutet, dass sich die Patient_innen in der Kombinationsbehandlung schneller verbesserten als die Patient_innen, die nur eine Einzeltherapie erhielten. Eine vorgeschaltete Gruppenbehandlung erhöht die Effizienz ambulanter KVT bei Depression im Vergleich zu reiner Einzeltherapie
Cancer cells evade ferroptosis: sex hormone-driven membrane-bound O-acyltransferase domain-containing 1 and 2 (MBOAT1/2) expression
No full textIn a recent manuscript published in Cell, Liang et al. discovered novel ferroptosis regulators, membrane-bound O-acyltransferase domain-containing 1 and 2 (MBOAT1/2).1 These findings may have implications for ferroptosis-based cancer therapy ...[aus dem Beitrag
Immunological consequences of arsenic trioxide-induced necrosis
No full textThe exact mechanism of arsenic trioxide (ATO, As2O3) poisoning has been a mystery for centuries. While rumors even suggest that it might have killed Napoleon, more recent work suggests ATO as a potential treatment option for acute promyelocytic leukemia [1]. While the potency of ATO in cell killing has been recognized, hardly anyone has considered the immunological consequences of cell death in tumors or tissues following ATO treatment. In this issue of Cellular and Molecular Immunology, Chen et al. address this question, adding yet another chapter to the complex relation between cell death and the immune response... [aus dem Beitrag