Localization and propagation of curvature under pure bending in steel tubes with Lüders bands

AbstractThe paper examines the plastic bending of steel tubes exhibiting Lüders bands through a combination of experiments and analyses. In pure bending experiments on tubes with diameter-to-thickness ratio of 18.8 tested under end-rotation control, following the elastic regime the moment initially traced a somewhat ragged plateau. At the beginning of the plateau Lüders bands appeared on the tension and compression sides of the cross section and simultaneously the curvature localized in one or two short zones while the rest of the tube maintained a much lower curvature. As the rotation of the ends was increased, one of the higher curvature zones spread at a nearly steady rate, affecting an increasingly larger part of the tube. When the whole tube was deformed to the higher curvature, the moment started to gradually increase while the tube deformed uniformly. A moment maximum was eventually attained and the structure failed by localized diffuse ovalization without any apparent effect from the initial Lüders bands-induced propagating instability. The problem was analyzed using 3D finite elements with a fine mesh. The material was modeled as an elastic–plastic solid with an up–down–up response over the extent of the Lüders strain, followed by hardening. The calculated response reproduced all major structural events observed experimentally including the initiation of the Lüders deformation, the moment plateau that followed, its extent, and the curvature localization and propagation associated with it. As in the experiments, once the high curvature extended over the whole tube length, the response of the tube became stable and the curvature uniform. With further bending the increasing ovalization induced a limit moment at a very high curvature

Assessment of Moisture-Tolerant Coatings for Decreasing Open Top Construction Time

Open top construction is a practice commonly used in the construction of large structures, such as nuclear power plants, as it allows large equipment to be easily placed by lowering it into position from above. Doing so, however, requires the concrete floor to be finished and coated prior to placement. Current coating manufacturer recommendations state that concrete should be allowed to dry for a minimum of 28 days prior to coating application to avoid compromising the bond between the coating and the concrete or between coating layers that could result from excessive moisture. This requirement delays the construction process, adding significant costs. The ability to apply coatings without damage prior to 28 days would greatly reduce construction time and cost. Ten coating systems were evaluated in this study. The coatings were applied 7, 14, 21, 28, and 45 days after the end of wet curing. Coating adhesion was evaluated using the Standard Test Method for Pull-Off Strength of Coatings on Concrete Using Portable Adhesion Testers and the Standard Test Method for Evaluating Adhesion by Knife 7, 21, 28, and 56 days after application of the final top layer of the coating systems. Moisture vapor emission rate (MVER) and concrete relative humidity (RH) were monitored throughout the tests. Most but not all of the coatings investigated in this study may be applied to concrete as early as 7 days after completion of wet curing, at MVER values over 10 lb/1000 ft2/day (565 μg/m2/s) and internal relative humidity (RH) above 80%, without significant adverse effects on coating adhesion, offering the potential to speed open top construction of nuclear power plants. The thickness of concrete does not affect the value or rate of change in MVER or RH. Thicker coatings exhibit relatively poor performance in the knife test compared to thinner coatings. Coating systems should be evaluated to ensure that they can be successfully applied at early ages. Larger-scale prototype early-age applications should be performed and subjected to the full range of required testing for the appropriate Service Level prior to wide-scale application of these findings

Identification of Proteins Differentially Expressed in the Striatum by Melatonin in a Middle Cerebral Artery Occlusion Rat Model—a Proteomic and in silico Approach

Ischemic stroke is characterized by permanent or transient obstruction of blood flow, which initiates a cascading pathological process, starting from acute ATP loss to subsequent membrane depolarization, glutamate excitotoxicity, and calcium overload. Melatonin is a potent antioxidant that exerts protective effects in different experimental stroke models. In this study, melatonin effects were demonstrated by a proteomic and in silico approach. The proteomic study identified differentially expressed proteins by 2D gel electrophoresis in the striatum 24 h after middle cerebral artery occlusion. Proteomic analysis revealed several proteins with aberrant expression and was validated by western blot and immunofluorescence analysis. Homology modeling was performed to build 3D structures for γ-enolase, thioredoxin (TRX), and heat shock 60 (HSP60) by the template crystal structures using a protein data bank as a sequence database. The structure refinement of each model was achieved by energy minimization via molecular dynamic simulation, and the generated models were further assessed for stability by Procheck and ProSA. The models were processed for docking analysis using AutoDock Vina, and post-docking analysis was determined by discovery studio. The proteomic study showed decreased expression of γ-enolase, TRX, and protein phosphatase 2A subunit B and increased expression of collapsin response mediator protein 2 and HSP60 in the striatum after ischemic injury. Treatment with melatonin modulated the expression profiles of these proteins. This study demonstrated the neuroprotective role of melatonin in the ischemic striatum using a proteomic and in silico approach. Collectively, melatonin may act in a multimechanistic way by modulating the expression of several proteins in the ischemic striatum

Redox-induced mobilization of Ag, Sb, Sn, and Tl in the dissolved, colloidal and solid phase of a biochar-treated and un-treated mining soil

The aim of this work was to study the redox-induced mobilization of Ag, Sb, Sn, and Tl in the dissolved, colloidal, and sediment phase of a mining soil treated and untreated with biochar as affected by the redox potential (E-H)-dependent changes of soil pH, dissolved organic carbon, Fe, Mn and S. The experiment was conducted stepwise at two E-H cycles (+200 mV -> -30 mV -> +333 mV -> 0 mV) using biogeochemical microcosm. Silver was abundant in the colloidal fraction in both cycles, indicating that Ag might be associated with colloids under different redox conditions. Antimony, Sn and Tl were abundant in the colloidal fraction in the first cycle and in the dissolved fraction in the second cycle, which indicates that they are retained by colloids under oxic acidic conditions and released under reducing alkaline conditions. Release of dissolved Sb, Sn, and Tl was governed positively by pH, Fe, S, and dissolved aromatic compounds. Biochar mitigated Ag release, but promoted Sb, Sn, and Tl mobilization, which might be due to the wider range of E-H (-12 to +333) and pH (4.9-8.1) in the biochar treated soil than the un-treated soil (E-H = -30 to +218; pH = 5.9-8.6). Also, the biochar surface functional groups may act as electron donors for the Sb, Sn, and Tl reduction reactions, and thus biochar may play an important role in reducing Tl3+ to Tl+, Sb5+ to Sb3+, and Sn4+ to Sn2+, which increase their solubility under reducing conditions as compared to oxic conditions. Thallium and Sb exhibit higher potential mobility in the solid phase than Sn and Ag. Biochar increased the potential mobility of Sb, Sn, and Tl under oxic acidic conditions. The results improve our understanding of the redox-driven mobilization of these contaminants in soils

Antioxidant and neuroprotective effects of caffeine against Alzheimer's and Parkinson's disease: insight into the role of Nrf-2 and A2AR signaling

This paper reviews the results of studies conducted on the role of caffeine in the management of different neurological disorders, such as Parkinson's disease (PD) and Alzheimer's disease (AD). To highlight the potential role of caffeine in managing different neurodegenerative diseases, we identified studies by searching PubMed, Web of Science, and Google Scholar by scrutinizing the lists of pertinent publications. According to the collected overall findings, caffeine may reduce the elevated oxidative stress; inhibit the activation of adenosine A2A, thereby regulating the accumulation of Aβ; reduce the hyperphosphorylation of tau; and reduce the accumulation of misfolded proteins, such as α-synuclein, in Alzheimer's and Parkinson's diseases. The studies have suggested that caffeine has promising protective effects against different neurodegenerative diseases and that these effects may be used to tackle the neurological diseases and/or their consequences. Here, we review the ongoing research on the role of caffeine in the management of different neurodegenerative disorders, focusing on AD and PD. The current findings suggest that caffeine produces potent antioxidant, inflammatory, and anti-apoptotic effects against different models of neurodegenerative disease, including AD, PD, and other neurodegenerative disorders. Caffeine has shown strong antagonistic effects against the adenosine A2A receptor, which is a microglial receptor, and strong agonistic effects against nuclear-related factor-2 (Nrf-2), thereby regulating the cellular homeostasis at the brain by reducing oxidative stress, neuroinflammation, regulating the accumulation of α-synuclein in PD and tau hyperphosphorylation, amyloidogenesis, and synaptic deficits in AD, which are the cardinal features of these neurodegenerative diseases

Analysis of post-migration traumatic events influence on immigrants and their personality traits

OBJECTIVES: This study aims to analyse the way immigrants and their personality traits get affected by traumatic events in the post-migration process. METHODS: This descriptive study was conducted through Google Forms with the involvement of 2,509 immigrants. A descriptive questionnaire, the "IFOMA Post-Migration Post-Traumatic Effect Scale" and the "GADOT Personality Types Determination Scale" were used to collect the research data. Independent samples t-test, one-way ANOVA, and related sample Friedman's two-way analysis tests were used in data analysis. RESULTS: Immigrants were exposed to significant effects in all sub-dimensions of the Post-Migration Post-Traumatic Effect Scale. Experiencing post-traumatic stress was found to be significantly related to the research parameters, which, respectively, are gender, age, marital status, educational background, legal status, years of living in the current country, employment status, ethnicity, Turkish language proficiency, and post-migration psychological problems (p < 0.05); 42.8% of the immigrants had the Type 9 personality, and all personality types were affected by the Psychological Affection, Physical Affection, Anxiety, and Social Adaptation sub-dimensions, respectively (p < 0.05). CONCLUSION: By analysing the impact of migration-induced trauma on immigrants within their society, it can be recommended to implement initiatives specific to immigrants' personality traits and to carry out protective/preventive projects that will minimize immigrants' exposure to trauma and encourage their participation in social adaptation processes

NF-κB Inhibitors Attenuate MCAO Induced Neurodegeneration and Oxidative Stress—A Reprofiling Approach

© Copyright © 2020 Ali, Shah, Zeb, Malik, Alvi, Alkury, Rashid, Hussain, Ullah, Ullah Khan, Koh and Li. Stroke is the leading cause of morbidity and mortality worldwide. About 87% of stroke cases are ischemic, which disrupt the physiological activity of the brain, thus leading to a series of complex pathophysiological events. Despite decades of research on neuroprotectants to probe for suitable therapies against ischemic stroke, no successful results have been obtained, and new alternative approaches are urgently required in order to combat this pathological torment. To address these problems, drug repositioning/reprofiling is explored extensively. Drug repurposing aims to identify new uses for already established drugs, and this makes it an attractive commercial strategy. Nuclear factor-kappa beta (NF-κB) is reported to be involved in many physiological and pathological conditions, such as neurodegeneration, neuroinflammation, and ischemia/reperfusion (I/R) injury. In this study, we examined the neuroprotective effects of atorvastatin, cephalexin, and mycophenolate against the NF-κB in ischemic stroke, as compared to the standard NF-κB inhibitor caeffic acid phenethyl ester (CAPE). An in-silico docking analysis was performed and their potential neuroprotective activities in the in vivo transient middle cerebral artery occlusion (t-MCAO) rat model was examined. The percent (%) infarct area and 28-point composite neuro score were examined, and an immunohistochemical analysis (IHC) and enzyme-linked immunosorbent assay (ELISA) were further performed to validate the neuroprotective role of these compounds in stroke as well as their potential as antioxidants. Our results demonstrated that these novels NF-κB inhibitors could attenuate ischemic stroke-induced neuronal toxicity by targeting NF-κB, a potential therapeutic approach in ischemic stroke

La résorption foliaire de quelques macro- (N, P, S) et micronutrients (Fe, Zn, Cu, Mn dans les forêts de Pterocarya fraxinifolia (Poiret) Spach en Turquie

Pterocarya fraxinifolia (Poiret) Spach a une distribution plutôt restreinte en Turquie dans les forêts marécageuses. La résorption foliaire de quelques macro- (N, P et S) et micronutriments (Fe, Mn, Zn, Cu) a été étudiée dans des populations de P. fraxinifolia du nord et du sud de la Turquie. Comparativement aux populations méridionales, les populations nordiques ont montré une résorption de l’azote (NRE) plus efficiente mais une résorption du phosphore (PRE) plus faible. Les populations tant nordiques que méridionales se sont montrées P-proficientes alors que seules les populations nordiques se sont révélées P-proficientes. Des valeurs négatives pour ZnRE et MnRE ont été trouvées dans les populations méridionales. SRE s’est révélée plus élevée que celle d’autres espèces décidues. Des ratios NRE/PRE > 1 ont été trouvés dans les populations nordiques mais 1 in northern populations, while <1 in southern populations

Pathological Comparisons of the Hippocampal Changes in the Transient and Permanent Middle Cerebral Artery Occlusion Rat Models

© Copyright © 2019 Shah, Li, Kury, Zeb, Khatoon, Liu, Yang, Liu, Yao, Khan, Koh, Jiang and Li. Ischemic strokes are categorized by permanent or transient obstruction of blood flow, which impedes delivery of oxygen and essential nutrients to brain. In the last decade, the therapeutic window for tPA has increased from 3 to 5–6 h, and a new technique, involving the mechanical removal of the clot (endovascular thrombectomy) to allow reperfusion of the injured area, is being used more often. This last therapeutic approach can be done until 24 h after stroke onset. Due to this fact, more acute ischemic stroke patients are now being recanalized, and so tMCAO is probably the “best” model to address these patients that have a potential good outcome in terms of survival and functional recovery. However, permanent occlusion patients are also important, not only to increase survival rate but also to improve functional outcomes, although these are more difficult to achieve. So, both models are important, and which target different stroke patients in the clinical scenario. Hippocampus has a vital role in memory and cognition, is prone to ischemic induced neurodegeneration. This study was designed to delineate the molecular, pathological, and neurological changes in rat models of t-MCAO, permanent MCAO (pMCAO), and pMCAO with diabetic conditions in hippocampal tissue. Our results showed that these three models showed distinct discrepancies at numerous pathological process, including key signaling molecules involved in neuronal apoptosis, glutamate induced excitotoxicity, neuroinflammation, oxidative stress, and neurotrophic changes. Our result suggests that the two commonly used MCAO models exhibited tremendous differences in terms of neuronal cell loss, glutamate excitotoxic related signaling, synaptic transmission markers, neuron inflammatory and oxidative stress molecules. These differences may reflect the variations in different models, which may provide valuable information for mechanistic and therapeutic inconsistences as experienced in both preclinical models and clinical trials