Finite Element Modelling of RC Beams Strengthened with Prestressed NSM CFRP Plate

Near Surface mounted (NSM) carbon fibre reinforced polymer (CFRP) reinforcement has become a promising flexural strengthening technique for reinforced concrete (RC) elements. The prestressing of a CFRP plate can be used to provide RC members with further enhancements in the flexural capacity. The aim of this study was to introduce a three-dimensional nonlinear finite element analysis (FEA) of RC beam strengthened by prestressed CFRP plate. Although there is a wide range of commercial programs for three-dimensional nonlinear FEA, they have different capabilities to model complex behaviour of composite materials such as RC beams strengthened with prestressed CFRP plate and the contact interaction. Therefore, the ABAQUS finite element package was used in this study due to its known accuracy to model the behaviour of a variety of materials such as concrete and its powerful contact algorithms. Concrete material was modelled using concrete damage plasticity (CDP) constitutive model, and steel reinforcements were modelled as elastic-perfectly plastic material. The CFRP plate was modelled as perfectly elastic material that fails at maximum tensile strain. Perfect bond was assumed between concrete and steel reinforcement, and a contact model was used to represent the behaviour between concrete and the CFRP plate. The results of the FEA were validated against experiment results reported in the literature. The results were compared in terms of the load-deflection behaviour, crack patterns, and mode of failure (rupture or debonding of CFRP plate). Based on the validation, the proposed FEA model was capable of capturing the behaviour of RC beams strengthened with prestressed CFRP plate. A parametric study was conducted to investigate the effect of prestressing levels, steel grades, and thickness, width, and length of the CFRP plate. It was observed that increasing prestressing of the CFRP plate improved the strength of the RC beam especially for the ultimate load. However, as the prestressing increased, the mode of failure changed to the rupture of the CFRP plate which limited further increase of the ultimate load. Using a higher steel grade improved the load carrying capacity. Increasing the width of the CFRP plate improved the load carrying capacity by delaying the debonding at the CFRP-concrete interface. Increasing CFRP plate thickness further improved the load carrying capacity of the beam. Increasing the length of the CFRP plate developed the general load carrying capacity; however, it was found that covering 25% of the shear span of RC beams provided sufficient and cost effective strengthening. The FE model offers a reasonable representation of the experimental results for load-deflection curve, failure modes and crack patterns

Knowledge management and university education outputs "Scientific Review"

This study dealt with a scientific review of the subject of knowledge management and the outputs of university education, where many Arab and foreign research efforts were reviewed that dealt with the importance of knowledge management and its relationship to improving the outputs of university education. A number of specialized and accredited databases, and the study terms have been tracked since the beginning of its appearance, it has been shown through tracking that the beginning of the emergence of the term knowledge management was in 1980 and at the first American Conference on Artificial Intelligence, but the real beginnings of knowledge management were in the nineties when it became The hot and most dynamic topics in the intellectual production of business administration, especially after the publication of Nonaka and Taikoshi in 1995 AD for a book entitled Creative Companies for Knowledge Management (Buran, 2016) that the actual interest in the subject of knowledge management and the outputs of university education began long ago, but at a low pace and weakness that, according to what The researcher reviewed it and the specified time period at the beginning of the year 2000 AD, and the number of foreign studies began to increase significantly, as studies appeared that were directly related to the term knowledge management and the outputs of university education, and studies followed successively during the years 2001-2006 until the last study was in the current year 2021 AD.                                 &nbsp

Modulation of Endothelial Interleukin-1β Inflammation

Atherosclerosis, complex chronic inflammatory disease, has a heterogonous aetiology. Endothelium is critically involved in the pathogenesis of atherosclerosis by producing proinflammatory cytokines, including interleukin-1 beta (IL-1β). However, the mechanism by which IL-1β is released is unknown. Neutrophil elastase (NE; a potent serine protease) has been shown to cleave proIL-1β in vitro. Therefore, I hypothesised that NE induces IL-1β secretion from endothelial cells (ECs). I found that NE cleaves proIL-1β in ECs and causes significant secretion of mature IL-1β into supernatant. The release is via extracellular vesicles (EVs), associated with a transient increase in intracellular Ca2+. The released IL-1β is significantly attenuated by inhibition of NE, but not caspase-1. Intracellularly, IL-1β is detected within LAMP-1 positive organelles only after NE treatment. Two distinct populations of vesicles, containing IL-1β are found: at early time points, intracellular vesicles (100-200μm), associated with detection of MV shedding enriched of IL-1β; however, at later time points, IL-1β was detected inside ECs in (>200μm) multivesicular bodies (MVBs) containing exosomes. In a second study, in experimental atherosclerosis, I attempted to manipulate inflammation using omega-3 fatty acids (n3FAs). I hypothesised that docosahexaenoic acid (DHA), the main n3FAs in fish oil, would inhibit inflammation by an IL-1β driven mechanism. I found that DHA significantly decreased high blood pressure and left ventricular mass induced by high fat diet in ApoE-/- mice. Interestingly, this is associated with a reduction in distal vessel atheroma and plasma proinflammatory markers. Locally, DHA also significantly attenuates eNOS and endothelial IL-1β expressions. This study reveals a hitherto unexplained mechanistic link between NE expression in atherosclerotic plaques and concomitant bioactive IL-1β secretion from ECs, highlighting the possibility of targeting NE to control IL-1β-induced atherosclerosis. It also sheds a light, for the first time, on how DHA can act as an anti-atherogenic agent through its effects upon IL-1 system

Dietary Docosahexaenoic Acid Reduces Oscillatory Wall Shear Stress, Atherosclerosis, and Hypertension, Most Likely Mediated via an IL‐1–Mediated Mechanism

Background: Hypertension is a complex condition and a common cardiovascular risk factor. Dietary docosahexaenoic acid (DHA) modulates atherosclerosis and hypertension, possibly via an inflammatory mechanism. IL‐1 (interleukin 1) has an established role in atherosclerosis and inflammation, although whether IL‐1 inhibition modulates blood pressure is unclear. Methods and Results: Male apoE−/− (apolipoprotein E–null) mice were fed either a high fat diet or a high fat diet plus DHA (300 mg/kg per day) for 12 weeks. Blood pressure and cardiac function were assessed, and effects of DHA on wall shear stress and atherosclerosis were determined. DHA supplementation improved left ventricular function, reduced wall shear stress and oscillatory shear at ostia in the descending aorta, and significantly lowered blood pressure compared with controls (119.5±7 versus 159.7±3 mm Hg, P<0.001, n=4 per group). Analysis of atheroma following DHA feeding in mice demonstrated a 4‐fold reduction in lesion burden in distal aortas and in brachiocephalic arteries (P<0.001, n=12 per group). In addition, DHA treatment selectively decreased plaque endothelial IL‐1β (P<0.01). Conclusions: Our findings revealed that raised blood pressure can be reduced by inhibiting IL‐1 indirectly by administration of DHA in the diet through a mechanism that involves a reduction in wall shear stress and local expression of the proinflammatory cytokine IL‐1β

Selective improvement of pulmonary arterial hypertension with a dual ETA/ETB receptors antagonist in the apolipoprotein E−/− model of PAH and atherosclerosis

Idiopathic pulmonary arterial hypertension (IPAH) is increasingly diagnosed in elderly patients who also have an increased risk of comorbid atherosclerosis. Apolipoprotein E deficient (ApoE-/-) mice develop atherosclerosis with severe PAH when fed a high-fat diet (HFD), and have increased levels of endothelin (ET)-1. ET-1 receptor antagonists (ERAs) are used for the treatment of PAH but less is known about whether ERAs are beneficial in atherosclerosis. We therefore examined whether treatment of HFD-ApoE-/- mice with macitentan, a dual ETA/ETB receptor antagonist, would have any effect on both atherosclerosis and PAH. ApoE-/- mice were fed chow or HFD for 8 weeks. After 4 weeks of HFD, mice were randomised to a 4-week treatment of macitentan by food (30mg/kg/day dual ETA/ETB antagonist), or placebo groups. Echocardiography and closed-chest right heart catheterisation were used to determine PAH phenotype and serum samples were collected for cytokine analysis. Thoracic aortas were harvested to assess vascular reactivity using wire myography, and histological analyses were performed on the brachiocephalic artery and aortic root to assess atherosclerotic burden. Macitentan treatment of HFD-fed ApoE-/- mice was associated with a beneficial effect on the PAH phenotype and led to an increase in endothelial-dependent relaxation in thoracic aortae. Macitentan treatment was also associated with a significant reduction in interleukin 6 (IL-6) concentration but there was no significant effect on atherosclerotic burden. Dual blockade of ETA/ETB receptors improves endothelial function and improves experimental PAH but had no significant effect on atherosclerosis

Calcium phosphate particles stimulate interleukin-1β release from human vascular smooth muscle cells: A role for spleen tyrosine kinase and exosome release

Aims: Calcium phosphate (CaP) particle deposits are found in several inflammatory diseases including atherosclerosis and osteoarthritis. CaP, and other forms of crystals and particles, can promote inflammasome formation in macrophages leading to caspase-1 activation and secretion of mature interleukin-1β (IL-1β). Given the close association of small CaP particles with vascular smooth muscle cells (VSMCs) in atherosclerotic fibrous caps, we aimed to determine if CaP particles affected pro-inflammatory signalling in human VSMCs. Methods and results: Using ELISA to measure IL-1β release from VSMCs, we demonstrated that CaP particles stimulated IL-1β release from proliferating and senescent human VSMCs, but with substantially greater IL-1β release from senescent cells; this required caspase-1 activity but not LPS-priming of cells. Potential inflammasome agonists including ATP, nigericin and monosodium urate crystals did not stimulate IL-1β release from VSMCs. Western blot analysis demonstrated that CaP particles induced rapid activation of spleen tyrosine kinase (SYK) (increased phospho-Y525/526). The SYK inhibitor R406 reduced IL-1β release and caspase-1 activation in CaP particle-treated VSMCs, indicating that SYK activation occurs upstream of and is required for caspase-1 activation. In addition, IL-1β and caspase-1 colocalised in intracellular endosome-like vesicles and we detected IL-1β in exosomes isolated from VSMC media. Furthermore, CaP particle treatment stimulated exosome secretion by VSMCs in a SYK-dependent manner, while the exosome-release inhibitor spiroepoxide reduced IL-1β release. Conclusions: CaP particles stimulate SYK and caspase-1 activation in VSMCs, leading to the release of IL-1β, at least in part via exosomes. These novel findings in human VSMCs highlight the pro-inflammatory and procalcific potential of microcalcification

Neutrophil Elastase Promotes Interleukin-1 beta Secretion from Human Coronary Endothelium

The endothelium is critically involved in the pathogenesis of atherosclerosis by producing pro-inflammatory mediators, including IL-1β. Coronary arteries from patients with ischemic heart disease express large amounts of IL-1β in the endothelium. However, the mechanism by which endothelial cells (ECs) release IL-1β remains to be elucidated. We investigated neutrophil elastase (NE), a potent serine protease detected in vulnerable areas of human carotid plaques, as a potential “trigger” for IL-1β processing and release. This study tested the hypothesis that NE potentiates the processing and release of IL-1β from human coronary endothelium. We found that NE cleaves the pro-isoform of IL-1β in ECs and causes significant secretion of bioactive IL-1β via extracellular vesicles. This release was attenuated significantly by inhibition of neutrophil elastase but not caspase-1. Transient increases in intracellular Ca2+ levels were observed prior to secretion. Inside ECs, and after NE treatment only, IL-1β was detected within LAMP-1-positive multivesicular bodies. The released vesicles contained bioactive IL-1β. In vivo, in experimental atherosclerosis, NE was detected in mature atherosclerotic plaques, predominantly in the endothelium, alongside IL-1β. This study reveals a novel mechanistic link between NE expression in atherosclerotic plaques and concomitant pro-inflammatory bioactive IL-1β secretion from ECs. This could reveal additional potential anti-IL-1β therapeutic targets and provide further insights into the inflammatory process by which vascular disease develops

Open Data from the Third Observing Run of LIGO, Virgo, KAGRA, and GEO

The global network of gravitational-wave observatories now includes five detectors, namely LIGO Hanford, LIGO Livingston, Virgo, KAGRA, and GEO 600. These detectors collected data during their third observing run, O3, composed of three phases: O3a starting in 2019 April and lasting six months, O3b starting in 2019 November and lasting five months, and O3GK starting in 2020 April and lasting two weeks. In this paper we describe these data and various other science products that can be freely accessed through the Gravitational Wave Open Science Center at https://gwosc.org. The main data set, consisting of the gravitational-wave strain time series that contains the astrophysical signals, is released together with supporting data useful for their analysis and documentation, tutorials, as well as analysis software packages

All-sky search for gravitational wave emission from scalar boson clouds around spinning black holes in LIGO O3 data

This paper describes the first all-sky search for long-duration, quasimonochromatic gravitational-wave signals emitted by ultralight scalar boson clouds around spinning black holes using data from the third observing run of Advanced LIGO. We analyze the frequency range from 20 to 610 Hz, over a small frequency derivative range around zero, and use multiple frequency resolutions to be robust towards possible signal frequency wanderings. Outliers from this search are followed up using two different methods, one more suitable for nearly monochromatic signals, and the other more robust towards frequency fluctuations. We do not find any evidence for such signals and set upper limits on the signal strain amplitude, the most stringent being ≈10−25 at around 130 Hz. We interpret these upper limits as both an “exclusion region” in the boson mass/black hole mass plane and the maximum detectable distance for a given boson mass, based on an assumption of the age of the black hole/boson cloud system

Searches for Gravitational Waves from Known Pulsars at Two Harmonics in the Second and Third LIGO-Virgo Observing Runs

We present a targeted search for continuous gravitational waves (GWs) from 236 pulsars using data from the third observing run of LIGO and Virgo (O3) combined with data from the second observing run (O2). Searches were for emission from the l = m = 2 mass quadrupole mode with a frequency at only twice the pulsar rotation frequency (single harmonic) and the l = 2, m = 1, 2 modes with a frequency of both once and twice the rotation frequency (dual harmonic). No evidence of GWs was found, so we present 95% credible upper limits on the strain amplitudes h $_{0}$ for the single-harmonic search along with limits on the pulsars’ mass quadrupole moments Q $_{22}$ and ellipticities ε. Of the pulsars studied, 23 have strain amplitudes that are lower than the limits calculated from their electromagnetically measured spin-down rates. These pulsars include the millisecond pulsars J0437−4715 and J0711−6830, which have spin-down ratios of 0.87 and 0.57, respectively. For nine pulsars, their spin-down limits have been surpassed for the first time. For the Crab and Vela pulsars, our limits are factors of ∼100 and ∼20 more constraining than their spin-down limits, respectively. For the dual-harmonic searches, new limits are placed on the strain amplitudes C $_{21}$ and C $_{22}$. For 23 pulsars, we also present limits on the emission amplitude assuming dipole radiation as predicted by Brans-Dicke theory