Estimating degradation of strength of neat PEEK and PEEK-CF laminates under cyclic loading by mechanical hysteresis loops

A method for assessing the degradation of mechanical properties of neat polyetheretherketone and its laminated composite reinforced with unidirectional carbon fibers is proposed. It is based on the calculation of the maximum and minimum strains in a cycle, as well as both dynamic and secant moduli estimated from mechanical hysteresis loops. These parameters reflect the material damage degree, enabling to predict its current mechanical state

Determination of Necessary and Sufficient Operational Conditions of The Sleeve-Type Bearings in Autonomous Power Plants of Ormat Type Under Conditions of Siberia and the Far East

The analysis of integral reliability characteristics for autonomous energy sources in gas pipelines of Russia is carried out. The reasons of the most frequent failures are determined. Recommendations for increase of integral reliability characteristics for autonomous energy sources are formulated

Computer simulation of stress-strain states in zygomatic bones after complex installation of implants

The research addresses evaluation of stress-strain state (SSS) in the “zygomatic bones–implants–denture base” system by varying the type and number of the zygomatic implants, as well as applying loads. The load magnitude was varied over a wide range, characteristic of the mastication process. Changing the adhesion conditions at the “zygomatic implant–bone tissue” interface varied both the level of maximum stress and the location of the critical stress concentrator. The local violation of the integrity of bone tissue in the skull was one of the key reasons for the redistribution of stresses in the “zigomatic implant­denture base” system. Such a phenomenon should be primarily taken into account when choosing the standard sizes of installed zygomatic implants in order to reduce the compliance of weakened areas of the skull (as the basis of the load-bearing structure). Based on the results of the FEM-based computer simulation, the algorithm was proposed for planning prosthetic treatment, which involves the iterative method for selecting both size and location of installing zygomatic implants depending on the results of the SSS calculation and the onset of a critical condition (primarily in bone tissue at the contact area with zygomatic implants)

Xenobiotic-induced activation of human aryl hydrocarbon receptor target genes in Drosophila is mediated by the epigenetic chromatin modifiers

Aryl hydrocarbon receptor (AHR) is the key transcription factor that controls animal development and various adaptive processes. The AHR\u27s target genes are involved in biodegradation of endogenous and exogenous toxins, regulation of immune response, organogenesis, and neurogenesis. Ligand binding is important for the activation of the AHR signaling pathway. Invertebrate AHR homologs are activated by endogenous ligands whereas vertebrate AHR can be activated by both endogenous and exogenous ligands (xenobiotics). Several studies using mammalian cultured cells have demonstrated that transcription of the AHR target genes can be activated by exogenous AHR ligands, but little is known about the effects of AHR in a living organism. Here, we examined the effects of human AHR and its ligands using transgenic Drosophila lines with an inducible human AhR gene. We found that exogenous AHR ligands can increase as well as decrease the transcription levels of the AHR target genes, including genes that control proliferation, motility, polarization, and programmed cell death. This suggests that AHR activation may affect the expression of gene networks that could be critical for cancer progression and metastasis. Importantly, we found that AHR target genes are also controlled by the enzymes that modify chromatin structure, in particular components of the epigenetic Polycomb Repressive complexes 1 and 2. Since exogenous AHR ligands (alternatively - xenobiotics) and small molecule inhibitors of epigenetic modifiers are often used as pharmaceutical anticancer drugs, our findings may have significant implications in designing new combinations of therapeutic treatments for oncological diseases. © Akishina et al

Estimating degradation of strength of neat PEEK and PEEK-CF laminates under cyclic loading by mechanical hysteresis loops

A method for assessing the degradation of mechanical properties of neat polyetheretherketone and its laminated composite reinforced with unidirectional carbon fibers is proposed. It is based on the calculation of the maximum and minimum strains in a cycle, as well as both dynamic and secant moduli estimated from mechanical hysteresis loops. These parameters reflect the material damage degree, enabling to predict its current mechanical state

U(1) gauged Q-balls and their properties

In the present manuscript, we briefly discuss the differences between ordinary Q-balls and U(1) gauged Q-balls. We focus on the differences in the existence of Q-ball solutions for appropriate values of the model parameters, as well as on the differences in classical stability of such Q-balls