High and Ultra-high Performance Concretes: A Solution to Reinforced Concrete Durability under Harsh Climate of Arabian Gulf

Reinforced concrete (RC) infrastructure in the Arabian Gulf region deteriorates under severe environmental conditions after only short service life. To overcome this problem, it is imperative to employ high-quality concretes and reinforce them with rebars that are corrosion resistant. This paper investigates the durability performance of newly developed high performance concretes (HPC) and ultra-high performance concretes (UHPC). The HPC and UHPC were manufactured using locally available materials in Qatar without employing any special treatment. The durability characteristics of HPC and UHPC in comparison to a normal strength concrete (NSC) were determined. Durability indicators such as concrete resistivity, sorptivity, porosity and resistance to chloride permeability were evaluated in order to access the durability of these concretes. These parameters were also compared to the concrete core samples taken from 30 to 50 years old RC structures in Doha city. The electrical resistivity of HPC and UHPC was 11 and 20 times higher than NSC, respectively. Sorptivity was 2 and 3 times less than NSC, respectively for HPC and UHPC. While the porosity of HPC and UHPC was 2.45 and 1.43% respectively. These newly fabricated concretes showed higher performance in durability testing than the concretes from real structures. With such attributes, the UHPC will be a useful tool in arresting the rapid deterioration of RC structures especially under harsh-climatic conditions of the Arabian Gulf.The funding for this research was provided by the National Priorities Research Program of the Qatar National Research Fund (a member of the Qatar Foundation) under the award no. NPRP 7-410-2-169. The statements made herein are solely the responsibility of the authors and do not necessarily reflect the opinions of the Sponsor

Study of failure symptoms of a single-tube MR damper using an FEA-CFD approach

From SAGE Publishing via Jisc Publications RouterHistory: epub 2020-11-03Publication status: PublishedA new magnetorheological (MR) damper has been designed, manufactured, modelled and tested under cyclic loads. A faulty behaviour of the damper was accidentally detected during the experiments. It was deduced that the presence of air bubbles within the MR fluid is the main reason for that failure mode of the damper. The AMT-Smartec+ MR fluid used in the current study, a new MR fluid whose characteristics are not available in the literature, exhibits good magnetic properties. However, the fluid has a very high viscosity in the absence of magnetic field. It is assumed that this high viscosity enables the retention of air bubbles in the damper and causes the faulty behaviour. To prove this assumption, a coupled numerical approach has been developed. The approach incorporates a Finite Element Analysis (FEA) of the magnetic circuit and a Computational Fluid Dynamics (CFD) analysis of the fluid flow. A similar approach was presented in a previous publication in which an ideal behaviour of an MR damper (no effect of air bubbles) was investigated. The model has been modified in the current study to include the effect of air bubbles. The results were found to support the assumptions for the reasons of the failure symptoms of the current MR damper. The results are shown in a comparative way between the former and current studies to show the differences in flow parameters, namely: pressure, velocity and viscosity, in the faultless and faulty modes. The results indicate that the presence of air bubbles in MR dampers reduces the damper force considerably. Therefore, the effect of the high yield stress of MR fluids due to the magnetic field is reduced

Performance of Mild Steel and Corrosion-Resistant Steel Rebars in Chloride-Contaminated Concrete

Reinforced concrete (RC) infrastructure in Arabian Peninsula is subjected to harsh climatic conditions of high temperatures, humidity, and airborne chlorides and there is a high concentration of salts in seawater and soils. These factors instigate corrosion of reinforcing steel in RC infrastructure at the early stages of the service life. To overcome the durability issues of RC infrastructures, corrosion-resistant reinforcing bars are employed. In this study, a comparison of microcell and macrocell corrosion of mild steel (MS) and two types of corrosion-resistant rebar namely the high chromium (HC) and stainless steel (SS) was established. Nine concrete block samples of 20x10x350 mm were cast with top rows of reinforcements, the top row consists of MS, HC, or SS, and the bottom row contained only SS. Blocks were conditioned under 3.5% NaCl for 2 years and linear polarization resistance and macrocell currents were evaluated to compare the corrosion performance of mild and corrosion resistant steel rebars. It was observed that SS is the most corrosion-resistant steel rebar, where high chromium steel showed up to three times more corrosion resistance than mild steel under chloride attack

Neuroprotective effect of oral administration of Trigonella Foenum-Graecum on chronic cerebral hypoperfusion in rat model

Introduction: Decreased cerebral blood supply to the brain can generate a condition of chronic cerebral hypoperfusion, which is one of the pathophysiological mechanisms of neuronal degeneration and cognitive impairment in Alzheimer’s disease. This study aimed to evaluate the potential neuroprotective effects of Trigonella foenum graecum seeds on chronic cerebral hypoperfusion in a rat model. Materials and Methods: Chronic cerebral hypoperfusion was induced by permanent bilateral ligation of the common carotid arteries (a two-vessel occlusion, 2VO) in male Sprague–Dawley rats. The experimental groups were divided into three groups (11 rats/group): i) sham (control) group; ii) 2VO group without any treatment; and iii) 2VO group that was administered orally with the Trigonella foenum graecum extract (100 mg/kg/day) by oral gavage from 3 days before the date of 2VO surgery and continued daily until the end of the 8th postoperative week. Spatial memory performance was assessed by the Morris water maze test. Malondialdehyde and C-reactive protein (CRP) concentration, superoxide dismutase and glutathione activities were measured in serum after 8 weeks from 2VO injury. Results: Chronic cerebral hypoperfusion rats resulted in spatial memory impairments. This behavioral dysfunction was accompanied by decreasing superoxide dismutase and glutathione activities, and increasing malondialdehyde and CRP levels in serum. Oral administration of Trigonella foenum graecum extract significantly improved the memory impairment, enhanced antioxidant enzyme activities, and decreased the malondialdehyde and CRP levels to near normal levels. Conclusion: The potential activity offered by Trigonella foenum graecum extract showed the neuroprotective effect that may be beneficial in cerebrovascular type dementia

Depression following major life transitions in women: a review and theory

Depression can occur due to common major life transitions, such as giving birth, menopause, retirement, empty-nest transition, and midlife crisis. Although some of these transitions are perceived as positive (e.g., giving birth), they may still lead to depression. We conducted a systematic literature review of the factors underlying the occurrence of depression following major life transition in some individuals. This review shows that major common life transitions can cause depression if they are sudden, major, and lead to loss (or change) of life roles (e.g., no longer doing motherly or fatherly chores after children leave family home). Accordingly, we provide a theoretical framework that explains depression caused by transitions in women. One of the most potential therapeutic methods of ameliorating depression associated with life transitions is either helping individuals accept their new roles (e.g., accepting new role as a mother to ameliorate postpartum depression symptoms) or providing them with novel life roles (e.g., volunteering after retirement or children leave family home) may help them overcome their illness

How circular design can contribute to social sustainability and legacy of the FIFA World Cup Qatar 2022™? The case of innovative shipping container stadium

The circular economy proposes a paradigm shift from the ‘take-make-waste’ type of economic system and aims to foster innovation, resource efficiency, and waste prevention. Mega sporting events can be considered great opportunities to promote sustainable cities and communities and leave a lasting positive legacy after the post-game stage. Qatar will organize the upcoming FIFA World Cup in 2022 and Ras Abu Aboud (RAA) is designed as a fully reusable and modular shipping container stadium, which will be dismantled, relocated, and reused after the tournament. This study aims to present the first comprehensive analysis on the social sustainability and legacy aspects of a circular and sharing economy application for the FIFA World Cup organization. The research analyzes the entire life cycle phases of the RAA stadium including the raw material production, construction, operations, and end-of-life. The Ecoinvent v.3.7.1 is used to quantify the midpoint environmental and endpoint human health impacts. For its operation phase assessment, two operation scenarios are comparatively analyzed: one-year temporary operation (Scenario 1) and 50 years of permanent operation (Scenario 2). Later, a simulation-based sensitivity analysis is conducted. Finally, we discussed how circular and modular design thinking can bring long-lasting legacy post-event, through reuse and recycling from a socio-economic perspective. An important finding shows that circular design under Scenario 1 can save up to 60% of human health impacts and significantly reduce the material footprint and dependence on imported construction materials. This research will enhance future awareness for sustainability benefits of circular and sharing economy application adopted by mega sporting events concerning the United Nations 2030 Agenda for Sustainable Development and FIFA's post-game legacy and sustainability strategies

Fracture Risk in Men With Congestive Heart Failure Risk Reduction With Spironolactone

ObjectivesThe purpose of this study was to determine whether spironolactone use is associated with fractures in men with congestive heart failure (CHF).BackgroundIn rats with aldosteronism, spironolactone preserves skeletal strength. However, in humans, the relationship of spironolactone to fractures is not known.MethodsThe medical records of all male patients with CHF from 1999 to 2005 treated at the Veterans Affairs Medical Center, Memphis, Tennessee, were reviewed (n = 4,735). Odds ratios with 95% confidence intervals of having a fracture associated with spironolactone use were estimated using conditional logistic regression.ResultsWe identified 167 cases with a single-incident fracture and matched these by age and race to 668 control subjects without fractures. After adjustment for covariates, spironolactone use was inversely associated with total fracture (odds ratio: 0.575; 95% confidence interval: 0.346 to 0.955, p = 0.0324).ConclusionsThe use of spironolactone is inversely associated with fractures in men with CHF

A phase 2 trial of consolidation pembrolizumab following concurrent chemoradiation for patients with unresectable stage III non–small cell lung cancer: Hoosier Cancer Research Network LUN 14-179

Background Five-year overall survival (OS) for patients with unresectable stage III non–small cell lung cancer (NSCLC) is poor. Until recently, a standard of care was concurrent chemoradiation alone. Patients with metastatic NSCLC treated with anti–programmed death 1 antibodies have demonstrated improved OS. This trial evaluated pembrolizumab as consolidation therapy after concurrent chemoradiation in patients with unresectable stage III disease. Methods Patients with unresectable stage III NSCLC received concurrent chemoradiation with cisplatin and etoposide, cisplatin and pemetrexed, or carboplatin and paclitaxel and 59.4 to 66.6 Gy of radiation. Patients with nonprogression of disease were enrolled and received pembrolizumab (200 mg intravenously every 3 weeks for up to 12 months). The primary endpoint was the time to metastatic disease or death (TMDD). Secondary endpoints included progression-free survival (PFS) and OS. Results The median follow-up for 93 patients (92 for efficacy) was 32.2 months (range, 1.2-46.6 months). The median TMDD was 30.7 months (95% confidence interval [CI], 18.7 months to not reached), which was significantly longer than the historical control of 12 months (P < .0001). The median PFS was 18.7 months (95% CI, 12.4-33.8 months), and the median OS was 35.8 months (95% CI, 24.2 months to not reached). The 1-, 2-, and 3-year OS estimates were 81.2%, 62.0%, and 48.5%, respectively. Forty patients (43.5%) completed 12 months of treatment (median number of cycles, 13.5). Symptomatic pneumonitis (grade 2 or higher) was noted in 16 patients (17.2%); these cases included 4 grade 3 events (4.3%), 1 grade 4 event (1.1%), and 1 grade 5 event (1.1%). Conclusions Consolidation pembrolizumab after concurrent chemoradiation improves TMDD, PFS, and OS in comparison with historical controls of chemoradiation alone. Rates of grade 3 to 5 pneumonitis were similar to those reported with chemoradiation alone