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Abstract Engineered Cementitious Composites (ECC) are highly regarded in construction owing to their tensile ductility and crack control capabilities, making them suitable for various structural applications. The accumulation of multi-walled carbon nanotubes (MWCNTs) further enhances their mechanical properties. However, there’s a significant knowledge gap concerning MWCNTs-ECC impact resistance. The objective of this study is to tackle the challenges associated with evaluating, optimizing, and predicting MWCNTs-ECC impact resistance to ensure its safe and widespread use in critical infrastructure by applying response surface methodology (RSM). Moreover, the 13 mixtures of ECC combined with several quantities of PVA fiber and MWCNTs as input elements were utilized to calculate the first (E1) and final (E2) impact energies. The findings demonstrated that the MWCNTs-ECC combinations’ impact resistance improved as the input ingredient concentrations increased. Besides, the optimum E1 and E2 of ECC combined with 1% of PVA fiber were noted by 1398 Joules and 12,956 Joules at 0.065% of MWCNTs on 28 days respectively. Furthermore, Response prediction models for E1 and E2 were created, and after being validated with an analysis of variance (ANOVA), it was determined that they had high R2 readings of 99.30% and 99.07%, correspondingly. The optimization process produced an ideal number of input variables for MWCNTs and PVA fiber, respectively, of 0.066% and 1%, with a desirability value of 100%. Moreover, it is recommended that the usage of 0.066% of MWCNTs in ECC combined with 1.0–1.50% PVA fiber provides optimum results for the construction industry.

The overuse of conventional fuels (coal, petroleum products, and gas) for energy generation causes natural resource depletion and global warming. Therefore, the utilization of Renewable Energy Sources (RES) in power systems is seeing rapid growth on a global level, particularly in offshore locations. This work aims to review the progress in developing hybrid RES power systems in offshore environments and optimization methods used for power generation using solar, wind, and wave energy systems. The papers published in peer-reviewed journals were collected from 2000 to 2023. A total of 143 articles were obtained and analyzed. The results demonstrated a rising trend in annual publications about the use of hybrid RES in electricity generation since 2007. The hybrid solar-wind and wind-wave energy systems have received a lot of attention due to technical advancements already developed for the wind energy system. Machine learning techniques, such as genetic algorithms (GA) and particle swarm optimization (PSO), have been extensively utilized in the field of renewable energy systems for tasks such as optimizing unit sizes, determining appropriate unit placements, minimizing costs, and maximizing power output. The methods are preferred due to their less complex structure. However, the practical application, true cost estimation and installation and maintenance studies at offshore locations are poorly developed. Also, the hybrid solar-wave and solar-wind-wave RES systems need further investigations for optimal mixing at the feasibility stage. The current review is the first of its kind, focusing on offshore renewable energy systems only.

Currently, the field of structural health monitoring (SHM) is focused on investigating non-destructive evaluation techniques for the identification of damages in concrete structures. Magnetic sensing has particularly gained attention among the innovative non-destructive evaluation techniques. Recently, the embedded magnetic shape memory alloy (MSMA) wire has been introduced for the evaluation of cracks in concrete components through magnetic sensing techniques while providing reinforcement as well. However, the available research in this regard is very scarce. This study has focused on the analyses of parameters affecting the magnetic sensing capability of embedded MSMA wire for crack detection in concrete beams. The response surface methodology (RSM) and artificial neural network (ANN) models have been used to analyse the magnetic sensing parameters for the first time. The models were trained using the experimental data obtained through literature. The models aimed to predict the alteration in magnetic flux created by a concrete beam that has a 1 mm wide embedded MSMA wire after experiencing a fracture or crack. The results showed that the change in magnetic flux was affected by the position of the wire and the position of the crack with respect to the position of the magnet in the concrete beam. RSM optimisation results showed that maximum change in magnetic flux was obtained when the wire was placed at a depth of 17.5 mm from the top surface of the concrete beam, and a crack was present at an axial distance of 8.50 mm from the permanent magnet. The change in magnetic flux was 9.50 % considering the aforementioned parameters. However, the ANN prediction results showed that the optimal wire and crack position were 10 mm and 1.1 mm, respectively. The results suggested that a larger beam requires a larger diameter of MSMA wire or multiple sensors and magnets for crack detection in concrete beams.

Early screening is a key component of intensive intervention therapy and rehabilitation for children with autism spectrum disorder (ASD). Electroencephalogram (EEG) signals provide real-time, high-sensitivity monitoring of pathological activities in children with ASD. This study used a dataset of 52 samples with 19-channel sleep data and proposed a new approach to diagnosing ASD based on energy differences between the left and right hemispheres of the brain. The preprocessing stage included decimation, band-pass filtering to remove unwanted frequencies, artifact subspace reconstruction to eliminate artifacts, and amplitude normalization to preserve the relative relationships between the signal features, which were crucial for the subsequent analysis and classification. Five band-pass filters were applied to decomposing the EEG signals. For each decomposed band, the signals from each brain hemisphere were analyzed separately by calculating the peak sensor’s envelope and obtaining the mean envelope for each hemisphere, resulting in two mean signals (right and left). Features were extracted using a sliding window approach applied to the mean signals of each hemisphere, with varying overlap ratios (12.5% to 87.5%, in 12.5% steps). The maximum, mean, and minimum energy values were used individually as features. Three types of SVM kernels—linear (L), the radial basis function (RBF), and quadratic—were employed for classification. The proposed method achieved the highest accuracy, sensitivity, and F1-score of 91.7%, 91.4%, and 91.6%, respectively, in the Theta band using SVM-L with the maximum energy features and the maximum overlap ratio.

There is a need in enhancing high-density concrete (HDC) for safeguarding sub-sea pipelines and constructing concrete mattresses for pipeline stabilization. To tackle these issues, a novel approach using a combination of supplementary cementitious materials like fly ash (FA) and graphene oxide (GO) have been successfully used in the partial replacement of the cement in this study. This research aims to enhance density, water resistance, and compressive strength properties for offshore applications by using GO and FA. A central composite design (CCD) of the response surface methodology (RSM) was employed, generating thirteen mixes with varying dosages of GO in the range of 0.013%–0.053% by weight of the cement and FA in the range of 20%–50% by weight of the cement. The HDC mixes exhibited enhanced characteristics, including an increased density of 4282 kg/m³, a maximum compressive strength of 37.9 MPa, and reduced water absorption at 2.52%. Response predicted models were established and validated through ANOVA, and multi-objective optimization was performed at a desirability of 58%. This yielded optimal GO and FA dosages of 0.013% and 37.87% respectively, for HDC with improved performance. The R2 values for the models range from 70% to 96%, showing a good level of the model quality. The findings present promising opportunities for more sustainable, cost-effective, and environmentally friendly HDC solutions for offshore applications.

This paper presents a novel, compact, and high gain metasurface (MS) patch antenna. The antenna structure consists of a slotted square patch in a fractal shape, integrated with a metasurface layer stacked on Taconic RF-30 dielectric material. The individual cells are arranged periodically, creating a 5 x 5-layer configuration. The proposed antenna is designed with physical dimensions of 290 x 290 mm² and achieves a maximum gain of 13.3 dBi at a frequency of 2.2 GHz. Moreover, it achieves a satisfactory minimum reflection coefficient of -10.9 dB. The design process and analysis were performed using the CST MWS simulation software. Based on the performance results obtained from this study, the suggested antenna can be considered suitable for applications in 5G communication.

With the increased use of engineered cementitious composite (ECC) in closed environments and as a structural material, it is necessary to fully understand its performance under elevated temperatures. This research investigates the response of ECC to ambient and elevated temperatures and addresses the issue of explosive spalling by incorporating graphene oxide (GO) and crumb rubber (CR). Twenty GO-modified rubberized ECC mixes were designed using Response surface methodology (RSM), considering GO content, GO concentration for CR pretreatment, CR replacement of fine aggregate, and elevated temperature as the input variables. Results show that mixes with GO and GO-treated CR outperform those without GO or untreated CR at ambient and elevated temperatures. Response predictive models exhibited high coefficient of determination (R2) values ranging from 84 % to 96 %. Multi-objective optimization yielded optimum input factors, resulting in improved mechanical properties that were experimentally validated to confirm the accuracy of the developed models.

Improving the physical properties of problematic soil has became fundamental consideration in various constructions, especially geotechnical engineering, to avoid failures, increase stability and strength of soil. Silty sand is one of the problematic soils and often encountered in the field where the fine gradation contained in the soil allows the soil to easily deform under pressure and lateral forces. In this study, silty sand was mixed with three variations of crumb rubber content (5, 10, and 15% based on soil weight), 6% cement (based on soil weight), and 0.05% graphene oxide (based on cement weight) to measurement and analysis of physical and mechanical properties. Soil Consistency limits, compaction testing using the Proctor Apparatus, and direct shear test were carried out for each mixed variable. The test results showed that the consistency limits and dry density decreases with increasing rubber content in the soil-cement matrix containing graphene oxide. Substitution of graphene oxide into the soil-cement matrix was able to increase in the stress and shear strength of the soil at each in variation in rubber content.

A crucial aspect of the design approach for bar-reinforced concrete buildings is the proper transfer of loads between the concrete and steel reinforcement via bonding. Bar pull-out tests were done to see how graphene oxide (GO) affected the bond strength, bond energy, and bond stress–slip response of deformed reinforcing bars implanted in engineered cementitious composites (ECC). This was done to improve the bond strength of steel/concrete composites. This article examines the bonding behaviour of steel reinforcing bars in a mixture of GO-modified ECC. The findings of pull-out assessments conducted on two distinct diameters (12 and 16 mm) of reinforcement steel bar inserted in ECC are initially provided. The investigation's findings are then utilised to determine the bond-slip interactions that describes the relations between the ECC mixtures and steel reinforcement bars. According to the experiment results, the introduction of GO as a nano-reinforcement in the ECC mixture had a considerable positive effect on the bar-matrix interactions owing to its bridging function. After 28 days, the bond strength of steel bars with widths of 12 and 16 mm was increased by 54.80% and 26.70%, respectively, when 0.05 wt% of GO was added to 1% of PVA fibre. The response surface methodology (RSM) is employed for developing predictive algorithms, which are then utilised in performing multi-variate optimization on bond-slip parameters, including bond strength, bond slip and bond energy. The acquired actual and predicted findings suggest that the created models are adequate for interpreting the bond performance of reinforcement steel bars in the GO-ECC.

Abstract People with HIV remain at greater risk for both infectious and non-infectious pulmonary diseases even after antiretroviral therapy initiation and CD4 cell count recovery. These clinical risks reflect persistent HIV-mediated defects in innate and adaptive immunity, including in the alveolar macrophage, a key innate immune effector in the lungs. In this proof-of-concept pilot study, we leveraged paired RNA-seq and ATAC-seq analyses of human alveolar macrophages obtained with research bronchoscopy from people with and without HIV to highlight the potential for recent methodologic advances to generate novel hypotheses about biological pathways that may contribute to impaired pulmonary immune function in people with HIV. In addition to 35 genes that were differentially expressed in macrophages from people with HIV, gene set enrichment analysis identified six gene sets that were differentially regulated. ATAC-seq analysis revealed 115 genes that were differentially accessible for people with HIV. Data-driven integration of the findings from these complementary, high-throughput techniques using xMWAS identified distinct clusters involving lipoprotein lipase and inflammatory pathways. By bringing together transcriptional and epigenetic data, this analytic approach points to several mechanisms, including previously unreported pathways, that warrant further exploration as potential mediators of the increased risk of pulmonary disease in people with HIV.

Locating facilities such as factories or warehouses is an important and strategic decision for any organization. Transportation costs, which often form a significant part of the price of goods offered, are a function of the location of the plans. To determine the optimal location of these designs, various methods have been proposed so far, which are generally definite (non-random). The main aim of the study, while introducing these specific algorithms, is to suggest a stochastic model of the location problem based on the existing models, in which random programming, as well as programming with random constraints are utilized. To do so, utilizing programming with random constraints, the stochastic model is transformed into a specific model that can be solved by using the latest algorithms or standard programming methods. Based on the results acquired, this proposed model permits us to attain more realistic solutions considering the random nature of demand. Furthermore, it helps attain this aim by considering other characteristics of the environment and the feedback between them.

Crumb rubber (CR) pretreatment methods effectively mitigate mechanical strength loss in cementitious composites. Yet, their impact on composite durability remains underinvestigated. This study examines the effect of CR pretreatment with graphene oxide (GO) on the durability of rubberized engineered cementitious composite (RECC), employing response surface methodology (RSM) for predictive model development and optimization. Water absorption, sulfate and acid resistance, compressive strength, and the porosity using mercury intrusion porosimetry were evaluated across 16 RSM-generated mixes using five GO concentrations (GOC) (0–1 mg/mL) and three pretreated CR (PCR) replacement levels (1–5%) as input variables. Results reveal increased resistance to water absorption, expansion, weight, and strength loss in sulfate and acid media with higher GOC levels across all PCR groups. Developed response predictive models demonstrate high R2 values (53–97%). Optimization resulted in 0.73 mg/mL and 2.5% for GOC and PCR, respectively.

Engineered cementitious composite (ECC) is a fiber-reinforced cementitious composite material that has garnered considerable attention from the building and scientific sectors. However, ECCs offer improved mechanical and durability characteristics compared to regular concrete. Fibers serve a crucial function in producing ultrahigh tensile ductility and autogenous fracture width control inside the micromechanical reinforcing system of ECC. This research discusses the various proportions of polyvinyl alcohol fibers (PVA) as reinforcing materials by total volume fraction in ECC in terms of mechanical properties performance, environmental consequences, and economic effects. A total of 60 ECC samples were cast to achieve the targeted compressive strength of 45 MPa of ECC mixture reinforced with 1%, 1.5%, and 2% of PVA fiber by the volume fraction. Though, the best compressive of ECC is calculated by 62.60 MPa at 1% of PVA fiber at 28 days. Besides, the tensile and flexural strengths are enhanced by 5.20 MPa, and 11.15 MPa at 1% of PVA fiber in ECC for 28 days respectively. In addition, the density of ECC is reduced with rises in the content of PVA fiber while water absorption is increased as the percentage of PVA fiber growths in the ECC after 28 days respectively. Moreover, the embodied carbon and energy are improved when the PVA fiber by the volume fraction increases in the mixture. It has been observed that the use of 1% PVA fiber by the volume fraction in cementitious composites is offering maximum strength and less embodied carbon and energy, therefore, it has been recommended for structural application.

A hand gesture recognition system provides a robust and innovative solution to nonverbal communication through human–computer interaction. Deep learning models have excellent potential for usage in recognition applications. To overcome related issues, most previous studies have proposed new model architectures or have fine-tuned pre-trained models. Furthermore, these studies relied on one standard dataset for both training and testing. Thus, the accuracy of these studies is reasonable. Unlike these works, the current study investigates two deep learning models with intermediate layers to recognize static hand gesture images. Both models were tested on different datasets, adjusted to suit the dataset, and then trained under different methods. First, the models were initialized with random weights and trained from scratch. Afterward, the pre-trained models were examined as feature extractors. Finally, the pre-trained models were fine-tuned with intermediate layers. Fine-tuning was conducted on three levels: the fifth, fourth, and third blocks, respectively. The models were evaluated through recognition experiments using hand gesture images in the Arabic sign language acquired under different conditions. This study also provides a new hand gesture image dataset used in these experiments, plus two other datasets. The experimental results indicated that the proposed models can be used with intermediate layers to recognize hand gesture images. Furthermore, the analysis of the results showed that fine-tuning the fifth and fourth blocks of these two models achieved the best accuracy results. In particular, the testing accuracies on the three datasets were 96.51%, 72.65%, and 55.62% when fine-tuning the fourth block and 96.50%, 67.03%, and 61.09% when fine-tuning the fifth block for the first model. The testing accuracy for the second model showed approximately similar results.

Industrialized construction continues to emerge globally. Developing countries like Malaysia are still unable to increase industrialized building system (IBS) implementation significantly, demonstrated by the low IBS percentage of less than 3%. Therefore, this research aims to determine the factors blocking IBS implementation through a mixed-methodological approach in the Malaysian construction industry. Using the data collected from 219 valid questionnaire responses, several statistical analyses were performed. Factor analysis was used to categorize the 25 factors into six main groups namely: “financial concerns,” “ineffective policies,” “technical and management worries,” “traditional stakeholders’ concerns,” “design restrictions” and “negative perception”. The top three critical factors are high initial capital cost, high initial cost of customized design, and transportation cost. Hence, adopting an innovative standardized design concept and increasing IBS manufacturers nationwide are recommended. The findings provide a useful guide to critical blocking factors and, thus, develop feasible solutions to achieve successful implementation of industrialized buildings.

Contamination of aquatic systems with pesticides occurs frequently. This study aimed to detect the levels of some pesticides: organochlorines, organophosphorus, pyrethroids, and carbamates groups in imported frozen and local fresh fish in Jordan. A total of 218 samples were randomly collected (194 imported frozen fish). Samples were analyzed using Liquid Chromatography with Tandem Mass Spectrometry (LC/Ms/Ms). Results showed that 23 different pesticides were found in this study. All 218 fish samples were contaminated with at least 4 compounds and maximally 12 pesticides. In terms of contamination rate, no significant differences between local and imported types were observed. Up to 65.2% of pesticides were detected at concentration higher than the maximum residue limit set by the WHO (10 ppb) in 215 samples (98.6%). These samples concluded heavy contaminations with different pesticides for either imported or locally raised products. Therefore, routine monitoring of pesticides in fish and their environment are officially required.

Waste materials may be used as raw materials for interlocking masonry products in order to contribute to sustainable development and environmental protection. Rubberized concrete Interlocking Brick (RCIB) was developed by volumetric replacement of 56% of the ordinary Portland cement with fly ash and 20% of the sand with crumb rubber (CR) to reduce the production cost of conventional concrete bricks (CCB) and restrict the depletion of natural resources and contributing to solving the environmental problems associated with the accumulation of scrap tires in landfills. The mechanical and sustainability evaluation of masonry prism made of the developed brick is the aim of this research. Consequently, compressive strength, failure mechanism, stress–strain behaviour, and energy absorption of grouted and ungrouted prisms made of RCIB were measured experimentally under axial compression load. The thermal resistance, fuel consumption, CO2 emission, and cost analysis of RCIBs were estimated. The findings reveal that grout had a significant impact on the compressive strength of rubberized concrete interlocking masonry prisms where the compressive strength of grouted and ungrouted prisms was 10.99 MPa and 5.83 MPa, respectively. Web splitting and vertical cracks were the common failure modes observed in both prisms. Moreover, the rubberized concrete interlocking masonry prisms revealed greater energy absorption as well as a gradual and ductile failure mechanism. The RCIB exhibited higher thermal resistance than CCB (increased from 0.106 to 0.171 m2 K/W) which could contribute to a 62% reduction in annual fuel consumption and CO2 emission. Further, more than 25% of the material cost could be saved.

Large expanses of green, open land are frequently converted as a result of population growth and quick development. This phenomenon causes the decreasing of water infiltration area which has an impact on increasing runoff coefficient. In the urban drainage problem, paving blocks are often used as road pavement construction materials to reduce surface runoff. The aim of this research is to study the characteristic of flow in the paving block made from plastic waste material. The research conducted in the laboratory testing utilizing a rainfall simulator by several variations in slope of 0% to 15%. The findings indicate that paving blocks made from plastic waste have less runoff coefficient than asphalt and/or concrete pavement. There is a correlation between the slope of the land and the runoff coefficient value which the runoff coefficient value increasing as the slope of the land increases. That finding is then applied in urban drainage problem located in the Cipamokolan Village region in Bandung City with the help of SWMM program for drainage calculation. As a result, the runoff discharge is decreasing by implementing the paving block made from plastic waste.

In this article, optimal energy consumption in the smart houses is studied considering techno-economic indices and demand side management (DSM) in electrical grids. The optimal energy consumption is implemented based on optimal scheduling of the household appliances than energy price and capacity of demand flexibility in DSM. The proposed approach is considered as two-stage optimization. Using first stage, energy consumption is modified by optimal shifting of the appliances subject to DSM and energy price. Thus, modified energy consumption is taken into accounted in second stage optimization to maximizing the consumers comfort and minimizing operation cost, simultaneously. The optimization process is done in the MATLAB software, in which objectives in second stage are optimized via lp-metric method. Finally, the performance of the proposed modelling is validated as case studies using numerical simulation.

In this paper, the study and simulation of turbulent flow inside a parabolic solar collector tube equipped with two spring insert samples with two different pitch ratios (P/D = 0.22, 0.44) and a specific cross-section are investigated. Heat transfer and properties of Cu–Fe3O4/Water hybrid nanofluid with volume fractions of φ = 1%, 3%, and 5% for the range of Reynolds numbers of 7000, 9000, and 11000 are selected and investigated using the single-phase method. The tube is used as the adsorbent pipe of a parabolic solar collector to investigate the performance of the parameters such as volume fraction, Nusselt number, pressure drop, parabolic solar collector efficiency, performance evaluation criterion, and field synergy principle. The results show that with decreasing the pitch ratio, Nu and solar collector efficiency increase. The maximum efficiency is 2.53 for a tube with P/D = 0.22 (Re = 7000, φ = 1%). The maximum efficiency is obtained under the same conditions in a tube containing the spring insert with P/D = 0.44 is equal to 2.39. At the same Reynolds numbers, the average of these velocities is significantly higher than a plain tube. Field Synergy Principle is a reliable criterion to investigate the mechanism of heat transfer increase that this coefficient value in the tube equipped with a spring insert is much higher than in a plain tube. This increase indicates the positive performance of the spring insert on the heat transfer rate and solar collector efficiency improvements. Therefore, spring inserts with a lower P/D are more desirable to achieve the highest efficiency of solar collectors as a source of renewable energy.

We conducted a survey study of clinical research coordinators (CRCs) at the member institutions of the Pediatric Emergency Care Applied Research Network, to determine the demographic and linguistic characteristics of CRCs around the network, and any perceived impact of those characteristics on their duties. A total of 53/74 CRCs completed the survey. Most respondents identified as “female,” “white,” and “not Hispanic/Latino.” Most respondents felt that their race/ethnicity and their ability to speak a language other than English would positively impact recruitment. Four female respondents felt that their gender hindered their recruitment efforts and their sense of belonging within the research team.

Graphene oxide (GO) is a 2D nanoparticle with dimensions less than 100 nm and acts as nano reinforcement in cementitious composites as a filling, crack-arresting agent, and nuclei for cement hydration. GO can be utilized to improve the microstructure and mechanical properties in a variety of construction and building technology applications. Through a coherent, comprehensive mixed reviewing method, this study seeks to evaluate the research efforts on utilizing GO in cementitious composites and map the research viewpoints from available literature (bibliometric analysis and systematic review). A total of 1437 publications were screened in which 59 articles were selected upon relevancy. Bibliometric mapping is used for keyword occurrence and the tested properties of cementitious composites containing GO. The review finds that the advantage of GO as a reinforcement in cement composite is that it is more effective in controlling crack development and propagation at the nano scale level in contrast to conventional reinforcement. The use of GO in cementitious composites offers many interesting paths and provides a foundation for further optimization in concrete, mortar, engineered cementitious composites, and cement paste. On the other hand, this use has a negative influence on various features of each type of reviewed material. More research is needed to gain a better knowledge of the long-term effects of the mechanical properties and durability of GO-based cementitious composites to promote their wider use in diverse applications in the construction sector.

Despite the excellent ductility and energy absorption properties of engineered cementitious composites (ECCs), a low modulus of elasticity and excessive drying shrinkage remain some of its major disadvantages. With the current trend in the application of nanotechnology in cementitious composites research, the effect of graphene oxide (GO) on the properties of ECCs is yet to be fully investigated, despite its promising results in ordinary cement paste, mortar, and concrete. ECCs need extensive material tailoring to provide the required mechanical characteristics and controlled fracture size with strain-hardening behavior. Striking a balance between these crucial hardened aspects of ECC without compromising any desired properties is a challenge. Hence, the main aim of the study reported in this paper is to use the response surface methodology (RSM) multi-objective optimization technique to identify an appropriate GO content via the weight of cement and also the volume fraction of polyvinyl alcohol (PVA) fiber as input variables that positively impact ECCs’ properties. Using RSM’s central composite design (CCD), 13 mixtures of various combinations of the variables (GO: 0.05%, 0.065%, 0.08%; PVA: 1%, 1.5%, 2%) were developed. Six responses were studied, including compressive strength, direct tensile strength, tensile capacity, flexural strength, modulus of elasticity, Poisson’s ratio, and drying shrinkage. Moreover, the microstructural properties of the composites were assessed using field-emission scanning electron microscopy (FESEM) and mercury intrusion porosimetry (MIP). The outcomes revealed that all the properties of ECCs were significantly enhanced by adding an optimum amount of 0.05% GO and 1–1.5% PVA fiber volume fractions. A maximum increase in 30%, 35%, 49%, and 33.9% in the compressive strength, direct tensile strength, flexural strength, and modulus of elasticity, respectively, of the mixes with 0.05% GO addition was recorded. It is demonstrated that the use of 0.05% GO as a nanoscale particle can provide good outputs for the construction industry.

The construction industry is increasingly focused on sustainability, with a particular emphasis on reducing the environmental impact of cement production. One approach to this problem is to use recycled materials and explore eco-friendly raw materials, such as alumino-silicate by-products like fly ash, which can be used as raw materials for geopolymer concrete. To enhance the ductility, failure mode, and toughness of the geopolymer, researchers have added crumb rubber processed from scrap tires as partial replacement to fine aggregate of the geopolymer. Therefore, this study aims to develop rubberized geopolymer concrete (RGC) by partially replacing the fine aggregate with crumb rubber (CR). To optimize the mechanical properties of RGC, response surface methodology (RSM) has been used to develop 13 mixes with different levels and proportions of CR (10–30% partial replacement of fine aggregate by volume) and sodium hydroxide molarity (10–14 M) as input variables. The results showed that the strength properties increased as the molarity of NaOH increased, while the opposite trend was observed with CR. The maximum values for compressive strength, flexural strength, and uniaxial tensile strength were found to be 25 MPa, 3.1 MPa, and 0.41 MPa, respectively. Response surface models of the mechanical strengths, which were validated using ANOVA with high R2 values of 72–99%, have been developed. It has been found that using 10% CR with 14 M sodium hydroxide resulting in the best mechanical properties for RGC, which was validated with experimental tests. The result of the multi-objective optimization indicated that the optimum addition level for NaOH is 14 M, and the fine aggregate replacement level with CR is 10% in order to achieve a rubberized geopolymer suitable for structural applications.

Chemical deterioration, including sulphate and acid attacks, is a major issue affecting the long-term durability of engineered cementitious composite (ECC) constructions that contact water from various sources, including groundwater, seawater, sewer water, and drinking water. This research enhances ECCs’ strength and resilience against chemical attack by combining cementitious composites with multiwalled carbon nanotubes (CNTs) and polyvinyl alcohol (PVA) fibre volume fractions using multiobjective optimization. The central composite design (CCD) of RSM was applied to generate thirteen mixes of different potential combinations of factors (multiwalled CNTs: 0.05% to 0.08%, PVA: 1–2%) and eight outcome responses were studied, although eight response models—six quadratic and two linear—were successfully designed and assessed using analysis of variance. The coefficients associated with R2 for all the models were exceptionally high, with values varying from 84 to 99 percent. The multiobjective optimization predicted the best outcomes and developed optimal values for both variables (CNTs: 0.05% and PVA: 1%). The results showed that, at 0.05% of CNTs in ECCs, an ultimate improvement of 23% in compressive strength was seen. Additionally, when CNTs are used to grow in the ECC matrix, the expansion owing to sulphate resistance and length change due to acid attack are both reduced. In addition, when the percentage of CNTs increases in ECCs, the weight loss and pH value owing to acid attack, as well as the rate of chloride permeability test results, are reduced. Furthermore, CNTs and PVA fibres with 0.05% and 1–1.5% concentrations offer optimal construction sector outcomes.

Engineered Cementitious Composites (ECC) are widely used in various structures due to their high strength, durability, and ductility. However, they are still vulnerable to environmental factors such as sulphate and acid attack. These attacks damage the concrete matrix, which leads to cracking and corrosion of the reinforcing steel. To mitigate these issues, various techniques have been developed, including the addition of graphene oxide to the ECC mix. Graphene oxide has shown potential in improving the mechanical properties and durability of ECC. The purpose of this study was to use multi-objective optimization to identify an appropriate GO by the weight of the cement and polyvinyl alcohol (PVA) fiber volume fraction in an ECC mixture. Using RSM’s central composite design (CCD), thirteen mixtures of various possible combinations of variables (GO: 0.05 percent to 0.08 percent, PVA: 1–2 percent) were established, and eight response responses (compressive strength, change in length, weight loss, pH test, weight gain, expansion, rapid chloride permeability test and water absorption) were examined. However, analysis of variance was used to effectively design and evaluate eight (six quadratic and two linear) response models. All the models had extremely high R2 values, ranging from 84 percent to 99 percent. The multi-objective optimization produced ideal variable values (GO: 0.05 percent and PVA: 1%) and projected optimum response values. The predicted values were verified experimentally and found to correlate extremely well with the experimental data, with less than a 5% error. The outcome showed that the maximum increase of 30% in the compressive strength was recorded at 0.05% of GO as a nanomaterial in ECC. In addition, the expansion due to sulfate resistance and change in length due to acid attack were decreased by 0.0023% and 0.28%, respectively, when the use of 0.08% of GO as a nanomaterial in the ECC matrix was reinforced with 1% PVA fiber for 28 days. Moreover, the weight loss and weight gain of ECC combined with 1% of PVA fiber due to chemical attack decreased by 66.70% and 77.80%, respectively, at 0.08% of GO as a nanoscale particle than that of the reference mix for 28 days. In addition, the pH value due to acid attack, rapid chloride permeability test value, water absorption, and slump flow of the fresh mixture were decreased as the concentration of GO rose in ECC. The results indicated that the incorporation of 0.05% GO as a nanomaterial and 1 to 1.5% of PVA fiber will provide the best outcomes for the construction industry.

Using the microwave-assisted method, novel Fe3O4/Zn-metal organic framework magnetic nanostructures were synthesized. The crystallinity, thermal stability, adsorption/desorption isotherms, morphology/size distribution, and magnetic hysteresis of synthesized Fe3O4/Zn-metal organic framework magnetic nanostructures were characterized by XRD patterns, TGA curve, BET adsorption/desorption technique, SEM image, and VSM curve, respectively. After confirming the Fe3O4/Zn-metal organic framework magnetic nanostructures, its antimicrobial properties against Gram-positive bacterial, Gram-negative bacterial, and fungal strains based on minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum fungicidal concentration (MFC) values were studied. The MIC values in antimicrobial activity for Gram-positive and Gram-negative bacterial strains, between 16–128 μg/ml, and for fungal strain, 128 μg/ml were observed. The results showed that the high specific surface area of Fe3O4/Zn-metal organic framework magnetic nanostructures caused the antimicrobial power of nanoparticles to be high, and the observed antimicrobial effects were higher than some known commercial antimicrobial drugs. Another advantage of the specific surface area of Fe3O4/Zn-metal organic framework magnetic nanostructures was its high catalytic properties in the three-component reaction of isatin, malononitrile, and dimedone. New spiro [indoline-pyranopyrimidines] derivatives were synthesized with high efficiency. The catalytic activity results of Fe3O4/Zn-metal organic framework magnetic nanostructures showed that, in addition to recyclability, derivatives could be synthesized in less time than previously reported methods. The results of investigating the catalytic activity of Fe3O4/Zn-metal organic framework magnetic nanostructures showed that the spiro [indoline-pyranopyrimidines] derivatives were synthesized in the time range of 10–20 min with an efficiency of over 85%. As a final result, it can be concluded that the microwave synthesis method improves the unique properties of magnetic nanostructures, especially its specific surface area, and has increased its efficiency.

Abstract As HIV has fueled a global resurgence of tuberculosis over the last several decades, there is a growing awareness that HIV-mediated impairments in both innate and adaptive immunity contribute to the heightened risk of tuberculosis in people with HIV. Since early immune responses to Mycobacterium tuberculosis (Mtb) set the stage for subsequent control or progression to active tuberculosis disease, early host–pathogen interactions following Mtb infection can be thought of as establishing a mycobacterial “set point,” which we define as the mycobacterial burden at the point of adaptive immune activation. This early immune response is impaired in the context of HIV coinfection, allowing for a higher mycobacterial set point and greater likelihood of progression to active disease with greater bacterial burden. Alveolar macrophages, as the first cells to encounter Mtb in the lungs, play a critical role in containing Mtb growth and establishing the mycobacterial set point. However, a number of key macrophage functions, ranging from pathogen recognition and uptake to phagocytosis and microbial killing, are blunted in HIV coinfection. To date, research evaluating the effects of HIV on the alveolar macrophage response to Mtb has been relatively limited, particularly with regard to the critical early events that help to dictate the mycobacterial set point. A greater understanding of alveolar macrophage functions impacted by HIV coinfection will improve our understanding of protective immunity to Mtb and may reveal novel pathways amenable to intervention to improve both early immune control of Mtb and clinical outcomes for the millions of people worldwide infected with HIV.

Globally, an estimated 107 million people have an alcohol use disorder (AUD) leading to 2.8 million premature deaths each year. Tuberculosis (TB) is one of the leading causes of death globally and over 8% of global TB cases are estimated to be attributable to AUD. Social determinants of health such as poverty and undernutrition are often shared among those with AUD and TB and could explain the epidemiologic association between them. However, recent studies suggest that these shared risk factors do not fully account for the increased risk of TB in people with AUD. In fact, AUD has been shown to be an independent risk factor for TB, with a linear increase in the risk for TB with increasing alcohol consumption. While few studies have focused on potential biological mechanisms underlying the link between AUD and TB, substantial overlap exists between the effects of alcohol on lung immunity and the mechanisms exploited by Mycobacterium tuberculosis (Mtb) to establish infection. Alcohol misuse impairs the immune functions of the alveolar macrophage, the resident innate immune effector in the lung and the first line of defense against Mtb in the lower respiratory tract. Chronic alcohol ingestion also increases oxidative stress in the alveolar space, which could in turn facilitate Mtb growth. In this manuscript, we review the epidemiologic data that links AUD to TB. We discuss the existing literature on the potential mechanisms by which alcohol increases the risk of TB and review the known effects of alcohol ingestion on lung immunity to elucidate other mechanisms that Mtb may exploit. A more in-depth understanding of the link between AUD and TB will facilitate the development of dual-disease interventions and host-directed therapies to improve lung health and long-term outcomes of TB.

Supplementary cementitious materials (SCMs) are strongly advised as an alternative to cement to reduce its adverse environmental effects. One such SCMs is palm oil fuel ash (POFA), a waste material generated in large quantities in Southeast Asian countries, and there is insufficient data on its use in engineered cementitious composite (ECC). This study aims to optimize the properties of ECC using POFA as a cement replacement, by using 13 mixes developed by response surface methodology (RSM) with the POFA (at 20, 30, and 40% cement replacement levels) and PVA fiber (at 1, 1.5, and 2% volume fractions) as the input factors. The compressive, tensile, and flexural strengths, and tensile capacity (CS, TS, FS, and TC) were assessed. The microstructural properties were determined using Field-Emission Scanning Electron Microscopy (FESEM) and Mercury Intrusion Porosimetry (MIP). Results indicated that while the ductility and strain capacity increased with POFA, the strengths decreased by up to 51.5%. However, a structural POFA-ECC could be made with up to 30% POFA and 1–5% PVA fiber. The RSM optimization revealed 27.68% POFA and 2% PVA fiber as the optimal levels of the input factors, with the experimental validation correlating with the predicted values at less than 10% error.

In this work, the shock wave response of a pore-embedded CuZr metallic glass (PEMG) under different impact velocities (0.5–1.5 km/s) and initial temperatures (300–600 K) was evaluated through the molecular dynamics (MD) simulation. The results indicated that the nucleation and growth of nanoscale shear events around the pore were the dominant mechanisms for plastic deformation under the shock wave. It was also found that the increase in the impact velocity led to the filling of pore, which was due to the structural softening and the local temperature increment in the vicinity of pore. Moreover, the spall event originated from the formation and coalescence of tension transformation zones, leading to the formation of nanovoids in the system. At higher velocities, the spallation was accompanied with the formation of more nanovoids with smaller sizes, inducing the brittle failure in the system. The MD outcomes also showed that the increase in initial temperature decreased the shock pressure and flow shear stress and led to the smoother spallation in the PEMG.

Electric vehicles with batteries have started to create a significant impact on the automobile industry nowadays. Along with battery manufacturers, automakers are developing new battery designs for electric vehicles, paying close attention to details like energy storage effectiveness, construction qualities, safety, affordability, and battery performance. The Chinese automaker developed the BYD Blade Battery Build Your Dream (BYD) in 2020. It is primarily a lithium iron phosphate (LFP) battery with prism-shaped cells, with an energy density of 165 Wh/kg and an energy density pack of 140Wh/kg. This essay briefly reviews the BYD Blade Battery’s performance compared to other battery models, model architecture, safety implications of the nail penetration experiment, and cost comparisons with other alternatives.

A recent development in the production of lightweight concrete is the use of bubble or hollow aggregates. Due to its exceptional energy absorption and ductility properties, engineered cementitious composite (ECC) is increasingly recommended and used for structural applications, particularly in earthquake-prone regions. As a result, researchers have started looking into the benefits of lightweight ECC for such applications. However, the strength is considerably compromised due to the use of lightweight fillers such as perlite, cenospheres, glass microbubbles, and crumb rubber (CR). This study evaluates an origami-shaped bubble aggregate (OBA) novel application in rubberized ECC (RECC) to achieve density reduction at a relatively lower strength loss. The experiment is designed using response surface methodology (RSM) with the spacing of the OBA at 10, 15, and 20 mm and its quantity at 9, 15, and 21 as the input factors (independent variables). The dependent variables (responses) assessed are density, compressive strength, modulus of elasticity, and Poisson’s ratio. The results showed that adding the OBA lowered the density of the RECC by 20%. It was revealed that using up to 15 OBAs with spacings between 15 and 20 mm, a lightweight OBA-RECC with substantial strength could be produced. Similarly, utilizing 15 and 21 OBAs at 20 mm spacing, a lightweight OBA-RECC with a comparable modulus of elasticity as the control could be developed. Models for predicting the responses were developed and validated using analysis of variance (ANOVA) with high R2 values. The spacing and quantity of the OBA’s optimal input levels were determined using the RSM multi-objective optimization to be 20 and 9, respectively. These levels produced optimal responses of 1899 kg/m3, 45.3 MPa, 16.1 GPa, and 0.22 for the density, compressive strength, modulus of elasticity, and Poisson ratio, respectively.

Abstract Twenty-seven large-scale beams with dapped-end have been prepared, cast and tested to failure in the three points loading arrangement. One control beam has been designed in accordance with requirement of standard code while the dapped-end reinforcement scheme of other beams has been derived from the control beam. In selected beams, engineered cementitious composites (ECC) has been utilized in the dapped-end region. The test results exhibited that DR is more appropriate and higher capacity than HR in resisting the shear force. In addition, the reinforced engineered cementitious composites dapped-end beams (R-ECC-DEB) showed higher structural performance compared to the normal reinforced concrete dapped-end beams (RC-DEBs). The strength of ECC also has direct effect on the failure capacity of the R-ECC-DEB, in which higher strength of ECC leads to higher failure capacity of R-ECC-DEB.

Engineered cementitious composite (ECC) requires a lot of material tailoring for the desired self-compacting properties at fresh state and controlled crack width with strain hardening behavior at hardened state to be attained. Finding a balance between these two important stages (fresh and hardened) of the composite without compromise on any of the desirable properties is not an easy task. This research was aimed at utilizing the technique of multi-objective optimization in trying to determine an optimal Polyvinyl alcohol (PVA) fiber volume fraction and HVFA replacement of cement (two of the most important ingredients of ECC) to develop a self-compacting HVFA-ECC (SC-HVFA-ECC) with desirable properties at both fresh and hardened stages without compromise. Using the central composite design (CCD) of RSM, 13 mixes of varying combinations of the input factors (PVA: 1–1.5 %, FA: 50–70 %) were developed on which six responses (fresh state: v-funnel time, T500 and slump flow; hardened state: compressive strength, flexural strength and tensile capacity) were investigated. Six response models (5 quadratic and 1 linear) were successfully developed and validated using ANOVA. All the models turned out to have a very high R2 value ranging from 87 to 97 %. The multi-objective optimization yielded optimal values of the variables (PVA: 1.67 % and FA: 53.61 %) and predicted optimized values for the responses. The predicted values were experimentally validated and found to compare very well with the experimental values at less than 5 % error.

Researchers have used crumb rubber in the manufacturing of engineered cementitious composites (ECC) as a solution for spalling, however, it reduces the mechanical and physical properties. Therefore, this research reviews the available and related literature reviews on rubberized ECC and its constituent. The role of each constituent in a rubberized ECC mix is also reviewed. It’s concluded that utilizing rubberized ECC helps to solve environmental issues relating to improper disposal of tyres. As a result, fly ash has been the most common substance utilized in rubberized ECC by scholars all over the world over the past years because of its encouraging impacts on rheology, matrix toughness control, and interactive effect between fiber and matrix. It’s also found that the rectification of the crumb rubber drawbacks in ECC is by incorporating a modern method of adopting nano-silica, Polyvinyl alcohol (PVA) fibers, graphene oxide into the rubberized ECC mixes. Therefore, rubberized ECC can be utilized for civil engineering applications, especially with the inclusion of nano-silica and graphene oxide, as a result of its high ductility and low permeability.

The bubble concrete (BC) produced by mixing high-strength hollow bodies into concrete has been proven to be effective in reducing density while maintaining strength. It has been verified that the position distribution of hollow bodies inside hardened BC significantly affects the compressive strength of the BC. However, the effect of hollow body material on the strength of BC has not yet been established. In the present paper, through concrete compression experiments and the nonlinear finite element analysis (F.E.A.), a comparative study of BC with three different hollow bodies—steel spheres, sand bonded stainless steel spheres, and ceramic spheres—has been carried out. The results show that the difference in elastic modulus of hollow bodies and concrete is the primary reason for the inhomogeneous stress distribution inside the concrete. The interface between the hollow body and hardened concrete could be increased using epoxy resin, thus enhancing the compressive strength of BC specimens by 26.6% compared to control concrete. The ceramic material is tightly integrated with the concrete, but as a brittle material, the ceramic cannot sustain colossal stress and subsequently breaks down.

The dapped-end reinforcements of a control beam have been designed conforming to requirement of the PCI code. The dapped-end reinforcements of other beams were derived from the control beam that involve the scheme variation of the hanger or diagonal reinforcements. Some selected beams utilize the engineered cementitious composites (ECC) in the dapped-end region. Twenty-seven large-scaled beams with dapped-end have been prepared, cast and tested. All beams were tested under the three-point loading up to failure. To localize effect of the shear failure, the shear span-depth ratio (av/d) of 1.43 has been carried out. Dapped-end beam (DEB) specified in PCI code has nominal shear span-depth ratio (an/d) less than 1, but in this study, several beams use an/d larger than 1. For analytical purpose, the design equations specified in PCI code have been used for the analysis requirement. By comparing against the test results, the analysis results that using the design equations of PCI code provide a significant difference, in which the mean value of analysis-test results ratio is 0.71. The design equations specified in PCI code were reliable to design the dapped-end reinforcements, but these equations have not yet able to accommodate adequately, in analyzing and predicting the failure load of DEBs that have the dapped-end reinforcements scheme varied.

Multi-layers of carbon fibre reinforced polymer (CFRP) were used to strengthen engineered cementitious composites (ECC) to study their effects on flexural and tensile strengths. Response Surface Methodology RSM was used to obtain the number of trial mixes. A total of 13 mix designs were suggested with two variables: polyvinyl alcohol (PVA) fibre (0.5 %, 1.25 % and 2.0 %) and number of CFRP (1, 3 and 5 layers). The result showed that the flexural strength of specimens with 0.5 % and 2.0 % PVA fibre was enhanced by more than 40 % and 55 %, respectively, when the CFRP layers were increased to 3 and 5 layers, which subsequently increased the absorption energy of the specimens by more than 20 %. Moreover, the tensile strength of the specimens with 1.25 % and 2.0 % PVA fibre improved by 31 % and 61 %, respectively, after these have been strengthened with 3 and 5 CFRP layers. To validate these results, the experimental responses were analysed and optimised using RSM. The coefficient of determination R2 yielded high values at 0.9647 and 0.9747, which indicated the good agreement of the proposed model to the experimental responses. Consequently, a quadratic model and a 2FI (two-factor interaction) model were developed to estimate the bond behaviour of CFRP-strengthened ECC. Based on these models, the best solution of CFRP strengthening with respect to the present study is to use 2 % PVA fibre and 5 layers of CFRP.

Since the mid-2000s, the transformation for the advanced 21st-century construction material has been on a headway utilizing the cutting-edge nanomaterials includes nano-silica, Carbon Nanotubes (CNTs), and Graphene Oxide (GO). GO is a recently invented only 2D carbon-based nanomaterial as it provides an additional dimension for the reactivity with cement composites. GO is an irresistible nanomaterial as it reforms the cement composite ranging from the atomic scale to macroscale and strengthens the mechanical properties (viz., compressive strength, tensile strength, flexural strength, and Young's modulus), durability and other multifunctional behavior. The availability of larger surface area and various oxygen-based functional groups form a linkage and contributes to the impressive behavior of the cementitious matrix. This research article presents a comprehensive review of the performance and behavior of cementitious composites tailored with GO nanomaterial.

The aim of this study is to evaluate the effects of inclusion nano-silica (also known as nano-SiO2) on the properties of pervious concrete containing fly ash (FA) as a partial replacement to cement. It has been found, for cementitious paste, that incorporating NS leads to reduce the cumulative pore volume by 13.4%. While the compressive strength of NS modified pervious concrete has been improved without adversely affecting its void ratio and permeability. The workability has been adversely affected by the inclusion of NS, which can be enhanced by incorporating the fly ash and superplasticizer. The porosity of cementitious paste has increased as the FA content is increased. These results are in good agreement with SEM results. For the pervious concrete voids ratio, permeability and infiltration rate were decreased against the increase of paste to the aggregate ratio Response surface methodology (RSM) has also been used to develop a model for navigating the design space of NS modified pervious concrete. Models revealed 95% significance of confidence level with difference less than 0.2 between Pred R-Squared value of 0.9515 and Adj R-Squared. The general expression has been developed for all the responses with the different coefficients using the RSM. Keywords: Fly ash, Final setting time, Infiltration rate, Pervious concrete, Nano-silica

Waste tires contribute badly to the environment on a huge scale as they are bulky, non-biodegradable, and prone to fire and being a shelter for mosquitos and other insects. This paper reports on a novel approach towards the development of rubberized brick by utilizing crumb rubber as the sole fine aggregate in the production of geopolymer interlocking bricks. The response surface methodology (RSM) from Design Experts software has been used to determine the numbers of trial mixes and their corresponding ingredients. A total of thirteen trial mixes were carried out and tested for compressive strength and the RSM model was developed to predict the design mix based on the targeted compressive strength. The mix design was obtained to be an 18 M for NaOH and 0.8 solution to fly ash ratio. The geopolymer interlocking rubberized bricks were then produced and tested for compressive strength, dimension, modulus of rupture, water absorption, initial rate of absorption, and efflorescence. The geopolymer interlocking rubberised bricks presented a low compressive and flexural strength and a high-water absorption capacity. The bricks were rated as non-effloresced and classified as 3rd class bricks which can be used as non-load bearing material. It is recommended to utilize nano silica in order to increase the strength of the brick. Keywords: Rubberized bricks, Crumb rubber, Interlocking bricks, Geopolymer, Response surface methodology

The major problems related to roller compacted concrete (RCC) pavement are high rigidity, lower tensile strength which causes a tendency of cracking due to thermal or plastic shrinkage, flexural and fatigue loads. Furthermore, RCC pavement does not support the use of dowel bars or reinforcement due to the way it is placed and compacted, these also aided in cracking and consequently increased maintenance cost. To address these issues, high volume fly ash (HVFA) RCC pavement was developed by partially replacing 50% cement by volume with fly ash. Crumb rubber was used as a partial replacement to fine aggregate in HVFA RCC pavement at 0%, 10%, 20%, and 30% replacement by volume. Nano silica was added at 0%, 1%, 2% and 3% by weight of cementitious materials to improve early strength development in HVFA RCC pavement and mitigate the loss of strength due to the incorporation of crumb rubber. The nondestructive technique using the rebound hammer test (RHT) and ultrasonic pulse velocity (UPV) were used to evaluate the effect of crumb rubber and nano silica on the performance of HVFA RCC pavement. The results showed that the use of HVFA as cement replacement decreases both the unit weight, compressive strength, rebound number (RN). Furthermore, the unit weight, compressive strength, RN, UPV and dynamic modulus of elasticity of HVFA RCC pavement all decreases with increase in crumb rubber content and increases with the addition of nano-silica. Combined UPV-RN (SonReb) models for predicting the 28 days strength of HVFA RCC pavement based on combining UPV and RN were developed using multivariable regression (double power, bilinear, and double exponential models). The exponential combined SonReb model is the most suitable for predicting the compressive strength of HVFA RCC pavement using UPV and RN as the independent variable with better predicting ability, higher correlation compared to the single variable models. Keywords: Crumb rubber, High volume fly ash, Nano silica, Roller compacted concrete pavement, Ultrasonic pulse velocity, Rebound number

The construction industry has been dealing with numerous issues in order to achieve the projects’ objectives. Hence, caused most projects to suffer low performance, particularly in terms of cost and time overrun and poor quality level. Regarding this matter, the last decade has shown a frequent failure of projects which clearly describes the need for a systematic investigation of the coordination process effects on the performance of the project. The study investigates the impression of coordination factors on projects performance by adopting structural equation modeling (SEM) technique via fit indices and standardised paths. In current research case data were obtained from a questionnaire distributed among owners/developers, contractors, and consultants. A theoretical structural equation model was developed to signify the effect of five main latent variables on project performance. The outcomes showed that projects with high performance have better coordination efficiency. Whereas, planning and scheduling factors (PSF) group is the highest significant group that had a great influence on performance, while records and documentation factors (RDF) group obtained the second important score. Overall, the outcome of this study is expected to contribute to the construction management efforts, particularly in addressing the root causes of poor performance and improving projects success.

In this present experimental study, geopolymer cement is developed using high calcium fly ash and used in the production of one-part alkali-activated binders. At 8–16 percent of the total precursor materials, the HCFA was activated with anhydrous sodium metasilicate powder and cured in ambient condition. Five mixtures of one-part geopolymer paste were intended at a steady w/b proportion. Density, flowability, setting time, compressive strength, splitting tensile strength and molar ratio impact were envisaged. It was observed that the setting time of the designed one-part geopolymer paste decreases with higher activator content. The experimental findings showed that the resistance of one-part geopolymer cement paste increases with comparatively greater activator content. However, raising the granular activator beyond 12 percent by fly ash weight decreases the strength and workability of the established one-part geopolymer cement. The optimum mix by weight of the fly ash was discovered to be 12 percent (i.e. 6 percent Na2O). At 28 days of curing, one-part alkali-activated paste recorded the greatest compressive strength of almost 50 MPa. The density of the one-part geopolymer paste is nearly the same regardless of the mixes. Microstructural assessment by FESEM, FTIR and XRD has shown that the established geopolymer paste includes quartz, pyrrhotite, aluminosilicate sodium and hydrate gels of calcium aluminosilicate. Based on the experimental information acquired, it can be deduced that the strength growth of one-part geopolymer cement is similar to that of Portland cement.

This paper proposes a new type of lightweight concrete called bubble concrete, which was developed by mixing concrete with high-strength hollow bodies. In the present study, concave and spherical steel hollow bodies were used not only to form multiple cavities in the concrete but also to transfer internal stresses. Through compression tests, the shape effects and distribution effects of the hollow bodies on the strength and Young’s modulus of concrete were investigated. In addition, the mechanical characteristics of the bubble concrete were simulated by nonlinear elastoplastic finite element analysis to study the stress distribution and failure mechanism. The results indicate that with the proper combination, bubble concrete can reduce its density to 1.971–2.003 g/cm3 (83.3–84.7%, compared to control concrete) and its strength reaches 27.536–28.954 N/mm2.

Takotsubo cardiomyopathy (TCM), also known as broken heart syndrome or stress-induced cardiomyopathy, is a rare condition with an estimated incidence of 0.02% of all hospitalizations in United States and 2% of all acute coronary syndrome presentations. TCM predominately presents as a transient wall motion abnormality of the left ventricular apex due to emotional or physical stress. Cardiac rupture in the setting of TCM is an extremely rare phenomenon with limited published case reports. We present a case of a 75-year-old female who had cardiac rupture secondary to TCM and performed a literature review using Ovid MEDLINE for published cases showing this association. After the literature review, we found 20 cases showing this association, which are listed in a tabular fashion.

Openings in reinforced concrete (RC) slabs are not commonly prescribed in design codes. Even when they are, they raise concerns regards to the size of the openings and the location of the applied loads. Lack of sufficient information about the load-carrying capacity of the slabs with openings and performance is another concern. Hence, this research addresses the structural behavior of slabs with openings coated with Carbon Fiber Reinforced Polymer (CFRP) sheet. In the experimental part, ten slabs were cast with a dimension of 1000 mm × 530 mm × 25 mm, among which nine slabs had openings and one slab was without opening (control slab). The configuration of the CFRP sheet includes coating in the form of single, double, and triple layers. Experimental results show that the slab with a triple coating of the CFRP layer offers the maximum resistance towards the loading rate. Moreover, with the increase in CFRP layers, the value of deflection is minimized.

Achalasia is a rare disease characterized by aperistalsis of the esophageal body and failure of the lower esophageal sphincter to relax. The etiology of this disease remains unknown. Polyglandular autoimmune syndrome type II is a well-identified disease characterized by the occurrence of autoimmune Addison's disease in combination with autoimmune thyroid disease and/or type 1 diabetes mellitus. We report a case that suggests autoimmunity and immunogenicity as a probable contributing factor for association of these two rare disorders.