•Performance of rubberized concrete with RCA and polypropylene fiber is studied.•Properties of rubberized concrete with RCA and polypropylene fiber are experimentally investigated.•Concrete with 30% ...RCA, 5% CR and 2% fiber shows the highest toughness/ductility.•Mechanical properties of the developed concrete are compared with code equations.
Scrap tire-derived crumb rubber (CR) in concrete, along with recycled coarse aggregate (RCA) and polypropylene fiber, constitute a way to reusing and recycling waste material and providing green and sustainable concrete structures. This study investigates the effect of substituting recycled constituents such as RCA and CR as a partial replacement of coarse aggregate and fine aggregate, respectively, along with polypropylene fiber addition into the concrete mixture. Fifteen different mixes are considered, with 10% and 30% RCA, 5% and 10% CR, and 1% and 2% fiber content. This study focuses on the experimental investigation of concrete combining RCA, CR, and fiber and evaluates its compressive strength, splitting tensile strength, and flexural strength at different ages. The compressive strength, splitting tensile strength, and flexural strength decrease as the CR content increases, but increase with the increasing fiber content. With regard to toughness and ductility, the effect of fiber is greater than that of RCA and CR, with each being found to increase with the incremental addition of fiber. It is also observed that the beams with fiber show failure in a more gradual manner. Finally, as a general recommendation in the interest of sustainability and environmental concern this paper suggests the use of rubberized concrete with RCA and polypropylene fiber for any structural purpose subjected to further investigations.
Bangladesh is currently facing a serious threat to public health, with 85 million people at risk from arsenic (As) in drinking water and in food crops. In Bangladesh, the groundwater As contamination ...problem is the worst in the world. Ninety-seven percent of the population in the country uses groundwater for drinking and domestic purposes as surfacewater is mismanaged. High levels of As in groundwater are causing widespread poisoning in Bangladesh. Different studies have addressed various aspects of the As issue in Bangladesh. This review is undertaken to give an overview of the latest findings and statistical data on the issue especially on soil, water and food cycle. The World Health Organization (WHO) recommends a safe limit for As in drinking water of 10
μg
L
−1. A recent survey looked at the As concentrations of drinking water from deep wells in 64 districts in the country and found that 59 had concentrations >10
μg
L
−1 and 43 had concentrations >50
μg
L
−1. Contaminated groundwater is also used for irrigation of paddy rice, which is the main staple food for the population. This practice enhances the level of As in the soils rendering them unsuitable for agriculture. A few recent studies have reported that 85–95% of total As in rice and a vegetable was inorganic, which outlines the need for more studies for standardization. Arsenic concentration is higher in Bangladeshi soils, groundwater and plants (data based on 4% area of the country) than the permissible limits or normal range reported. This situation poses a serious threat on human and livestock health and highlights the need for scientific studies that would better describes the fate of As in the natural environment and identify all potential routes of exposure.
We present a deep learning-based method that corrects motion artifacts and thus accelerates data acquisition and reconstruction of magnetic resonance images. The novel model, the Motion Artifact ...Correction by Swin Network (MACS-Net), uses a Swin transformer layer as the fundamental block and the Unet architecture as the neural network backbone. We employ a hierarchical transformer with shifted windows to extract multiscale contextual features during encoding. A new dual upsampling technique is employed to enhance the spatial resolutions of feature maps in the Swin transformer-based decoder layer. A raw magnetic resonance imaging dataset is used for network training and testing; the data contain various motion artifacts with ground truth images of the same subjects. The results were compared to six state-of-the-art MRI image motion correction methods using two types of motions. When motions were brief (within 5 s), the method reduced the average normalized root mean square error (NRMSE) from 45.25% to 17.51%, increased the mean structural similarity index measure (SSIM) from 79.43% to 91.72%, and increased the peak signal-to-noise ratio (PSNR) from 18.24 to 26.57 dB. Similarly, when motions were extended from 5 to 10 s, our approach decreased the average NRMSE from 60.30% to 21.04%, improved the mean SSIM from 33.86% to 90.33%, and increased the PSNR from 15.64 to 24.99 dB. The anatomical structures of the corrected images and the motion-free brain data were similar.
The growth of unavoidable waste rubber and the demolition of old concrete structures have become a concern for environmental sustainability. The incorporation of crumb rubber and demolished concrete ...into the new concrete mix is likely to promote environmentally friendly practices. This paper investigates the shear behavior of concrete beams containing crumb rubber (CR), recycled concrete aggregate (RCA), and polypropylene (PP) fiber. A total of fifteen reinforced concrete (RC) beams were prepared with recycled concrete aggregate (RCA) (0%–50%), CR as fine aggregate (0%–10%), and PP fiber fractions (0%–1%). All RC beams made without any shear reinforcement were tested under a four-point bending test up to failure. The ultimate shear strength, crack pattern, post-diagonal cracking, concrete strain, toughness, and deformation behavior of fresh concrete properties were investigated at different combinations. The surface strain of concrete was closely observed by using Digital Image Correlation (DIC) technique. The experimental result suggested that the introduction of CR in the concrete mix negatively affects the ultimate shear strength, post diagonal cracking resistance, toughness, and deformability of the beam. These effects may be remedied and enhanced by inserting PP fiber in the concrete at RCA replacement levels up to 30%. The beam made of 30% RCA along with 5% CR and 1% PP fiber demonstrated the best performance in terms of shear resistance, deformability, and toughness. Interestingly, the application of 50% RCA with or without CR and PP fiber adversely affected the shear strength parameters of concrete. The beam deformability increased with the addition of a small percentage of rubber (up to 5%). The post-diagonal crack resistance increased with the presence of fibers, whereas the response is the opposite with the addition of rubber.
In this study, total concentrations of 16 trace elements (Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Sb, Hg, Pb, Th and U) in sediments of the rivers of the Sundarban mangrove forest, after the ...catastrophic oil spill accident in the Sela river of Sundarban, were determined. The overall mean concentrations of V, Cr, Fe and Cd in surface sediments of the Sundarban are remarkably higher than available literature data of those elements. Trace element contamination assessment, using different environmental contamination indices, reveals that As, Sb, Th and U are low to moderately contaminated while Cd is moderately to severely contaminated in the sediments of this area. The multivariate statistical analyses were applied to reveal the origin and behavior of the elements during their transport in the mangrove ecosystem. High Cr, Ni, Cu and As concentrations suggest the risk of potentially adverse biological effects in the ecosystem.
•Total 16 elements in sediments of the Sundarban mangrove forest were determined.•The contents of V, Cr, Fe and Cd are higher than those available literature data.•Trace element contamination indices and ecological risk of toxicity were assessed.•The statistical analyses reveal the origin and transport behavior of the elements.
The Surface Water and Ocean Topography (SWOT) satellite mission planned for launch in 2020 will map river elevations and inundated area globally for rivers >100 m wide. In advance of this launch, we ...here evaluated the possibility of estimating discharge in ungauged rivers using synthetic, daily “remote sensing” measurements derived from hydraulic models corrupted with minimal observational errors. Five discharge algorithms were evaluated, as well as the median of the five, for 19 rivers spanning a range of hydraulic and geomorphic conditions. Reliance upon a priori information, and thus applicability to truly ungauged reaches, varied among algorithms: one algorithm employed only global limits on velocity and depth, while the other algorithms relied on globally available prior estimates of discharge. We found at least one algorithm able to estimate instantaneous discharge to within 35% relative root‐mean‐squared error (RRMSE) on 14/16 nonbraided rivers despite out‐of‐bank flows, multichannel planforms, and backwater effects. Moreover, we found RRMSE was often dominated by bias; the median standard deviation of relative residuals across the 16 nonbraided rivers was only 12.5%. SWOT discharge algorithm progress is therefore encouraging, yet future efforts should consider incorporating ancillary data or multialgorithm synergy to improve results.
Key Points:
SWOT discharge algorithms were tested on synthetic observations for 19 rivers
Algorithms accurately characterized temporal dynamics of river discharge
At least one algorithm estimated discharge to <35% relative RMSE on 14/16 of nonbraided rivers
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•This is a state-of-art review of rubberized recycled aggregate concrete (RRAC) and fiber-reinforced rubberized recycled aggregate concrete (FRRAC).•Different mechanical properties, ...microstructural analysis, and life cycle assessment of RRAC and FRRAC have been reviewed.•Extensive regression analysis has been conducted to predict different mechanical properties of RRAC and FRRAC.•Crumb rubber (CR) and recycled coarse aggregate (RCA) reduced the strength, however, fiber addition could have a positive response.•Addition of CR and fibers enhanced the toughness and ductility of RRAC; however, excessive amount of CR negatively affected the toughness.•RCA and CR can be used up to 30% and 10%, respectively.
The growing population demands rapid development of infrastructures. However, the construction industry is searching for environmentally sustainable and eco-friendly building materials to fight climate change. Millions of tires are discarded globally, and only certain percentages are recycled. The use of rubber tires as a natural aggregate replacement in concrete has gained popularity among the research community in the past few years, primarily due to its ductility and toughness properties. A significant number of investigations have been reported in the past using recycled coarse aggregates (RCA), crumb rubber (CR), and fibers separately in concrete. The results revealed that the addition of rubber particles along with RCA in concrete reduced the strength. However, the inclusion of fibers in the same mixtures significantly improved the mechanical properties of concrete by acting as a bridge within the concrete matrix for the surrounding cracks. In this review paper, over 220 research articles from the last 30 years reporting the effect of RCA, CR, and fibers on the mechanical and physical properties of rubberized recycled aggregate concrete (RRAC) and fiber-reinforced rubberized recycled aggregate concrete (FRRAC) are summarized. This paper presents in detail the influencing factors that affect the physical and mechanical properties of RRAC and FRRAC. The performance of FRRAC depends on the types of fiber and CR, treatment of CR, RCA sources, and the mix design of concrete. Based on the review, recommendations are provided for optimized FRRAC production. Simplified equations have been proposed to predict the tensile and flexural strength and modulus of elasticity of RRAC and FRRAC. An overview of predicting the mechanical properties of rubberized concrete using different machine-learning algorithms has been presented. Finally, this review paper will help scholars understand the use of RCA and CR in concrete as aggregate replacement materials and create waste material utilization opportunities for the sustainable green construction industry.
In this study, depth-wise concentration variations of twenty-five elements (Na, Al, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Zn, As, Sb, Cs, La, Ce, Sm, Eu, Dy, Yb, Lu, Hf, Th and U) and their contamination ...levels were studied using two sediment cores from two different Ranges of the Sundarbans mangrove forest, Bangladesh. It was observed that there was a decreasing trend in concentrations of most of the studied elements from surface to the deeper layers and the rate of concentration decrement at the core from Satkhira Range was less than that of the core from Chandpai Range, indicating a more anthropogenic effect on the Chandpai range near Mongla seaport area. Different pollution indices (I
geo
and EF) indicate that sediments of the Sundarbans are minor to moderately contaminated by As, Sb, Cs, REEs, Th and U. Therefore, this study suggests that proper steps should be taken to save the sensitive mangrove forest from elemental pollution.
The routine use of patient reported outcome measures (PROMs) in evaluating the outcome after arthroplasty by healthcare organisations reflects a growing recognition of the importance of patients' ...perspectives in improving treatment. Although widely embraced in the NHS, there are concerns that PROMs are being used beyond their means due to a poor understanding of their limitations. This paper reviews some of the current challenges in using PROMs to evaluate total knee arthroplasty. It highlights alternative methods that have been used to improve the assessment of outcome.
A hybrid glucose biosensor was developed based on glucose oxidase immobilized on platinum nanoparticles (PtNPs) decorated chemically derived graphene (CG) and carbon nanotube electrode platform for ...highly sensitive and selective glucose sensing. Chemically derived graphene and carboxylic groups functionalized multiwalled carbon nanotubes composite (C@MWCNTs) were synthesized using one step solvothermal technique to result in a suspension of the synthesized nanocomposite. The nanocomposite solution was drop casted on the gold electrode to form a thin film onto which PtNPs was electrochemically deposited. Glucose oxidase was immobilized on the nanostructured electrode and subsequently coated with nafion for selective glucose sensing. The fabricated hybrid biosensor exhibited good electrocatalytic activity towards glucose with a linear dynamic range of 0.5 mM to 13.5 mM with a fast response time of <5 s. A high sensitivity of 26.5 μA/mM cm2 and a low detection limit of 1.3 μM were observed. The biosensor exhibited a negligible response to common interference species such as uric acid, ascorbic acid and acetaminophen. The pH profile of the hybrid biosensor revealed an optimal pH operating range of 6.5 to 7, whereas the temperature profile revealed increasing oxidation current response with the increase in temperature. The obtained results thus indicate that the nanostructured composite material offers a large surface area and high electrocatalytic activity towards glucose and is a potential candidate material for glucose biosensors.
•Chemically derived graphene and carbon nanotube nanocomposites are synthesized.•PtNPs was electrochemically deposited on the surface of the nanocomposite film.•The synergy between PtNPs and CG/f@MWCNTs enhances the electrocatalytic activity•Glucose oxidase was immobilized to enhance the selectivity towards glucose.•The amperometric biosensor demonstrated great analytical performance.
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