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Applying industrial by-products as a substitution for conventional construction materials (natural resources) is a superior solution for the environment in terms of waste management and reduction in greenhouse emissions and for the construction industry in terms of cost and expenditure. Applying basic oxygen furnace slag (BOFS), one of the metallurgical industry by-products, as a construction material can be a high-potential and promising idea. However, the utilization of BOFS in construction applications is considerably limited because of its inherent characteristics leading to volumetric expansion behavior caused by the chemical reaction between free lime (f-CaO) and water. This study used geopolymer technology to stabilize the expansive behavior of chronologically aged BOFS aggregates. The compressive strength, expansion behavior, and drying shrinkage characteristics of a normal ordinary Portland cement (OPC) mixture and a geopolymer mixture containing siliceous river sand and chronologically aged BOFS aggregates were investigated. The test results showed that the compressive strength of geopolymer mixtures containing chronologically aged BOFS aggregate achieved 64.02 MPa, and the expansion behavior of geopolymer mixtures was improved compared with normal OPC mixtures containing the same BOFS aggregates, reaching 0.02% and 0.44%, respectively. However, due to the air-curing method, geopolymer mixtures had higher drying shrinkage values than normal OPC mixtures. Therefore, further studies should be conducted to investigate how to control the drying shrinkage of geopolymer mixtures containing chronologically aged BOFS aggregate. [ABSTRACT FROM AUTHOR]

Before using basic oxygen furnace slag (BOFS) in any engineering application, it is important to determine its properties. The chemical composition, mineralogy, and physical properties of BOF slag are subject to large fluctuations as a result of different raw additives, different compositions of the molten iron used for producing the steel, oxygen stirring of a molten pool, uneven temperature fields, and other complex physical conditions. Thus, in this research, the engineering properties of BOF slag aggregates with different ages were identified, and then the feasibility of BOF slag aggregates in mortar application was investigated. It was found that stockpiled BOFS was harder than fresh BOF slag, which had lower aggregate crushing values and lower LA abrasion values. Also, stockpiled BOFS showed less expansion than fresh BOF slag regardless of water and 1 M NaOH solution immersion. The chemical reaction between f-CaO, f-MgO, and water due to weathering in the field extremely reduced the expansion of BOFS submerged in water. BOFS may contain reactive silica, which causes an alkali–silica reaction (ASR). Stockpiled BOFS (100%, 75%, 50%, 25%) used as a mineral filler in asphalt concrete mix brought about low tensile strength at break up (crack), low compressive strength at +50 °C, poor cohesion, and residual porosity. However, these parameters were partially improved with the use of a thermostable adhesive additive for road bitumen based on polyphosphoric acid esters. The comprehensive assessment in this study indicates that while some mixtures meet the specified criteria for certain properties, there are challenges, particularly regarding crack resistance and cohesion, that need to be addressed to fully align with the standard. Adjustments to the mixture proportions, the exploration of alternative additives, and the use of different types of fillers may be necessary to achieve the desired properties, especially in terms of crack resistance and cohesion. [ABSTRACT FROM AUTHOR]

Antireflection coatings (ARCs) with an indium thin oxide (ITO) layer on silicon heterojunction solar cells (SHJ) have garnered significant attention, which is due to their potential for increasing current density (Jsc) and enhancing reliability. We propose an additional tungsten trioxide (WO3) layer on the ITO/Si structure in this paper in order to raise the Jsc and demonstrate the influence on the SHJ solar cell. First, we simulate the Jsc characteristics for the proposed WO3/ITO/Si structure in order to analyze Jsc depending on the thickness of WO3 using an OPAL 2 simulator. As a result, the OPAL 2 simulation shows an increase in Jsc of 0.65 mA/cm2 after the 19 nm WO3 deposition on ITO with a doping concentration of 6.1 × 1020/cm2. We then fabricate the proposed samples and observe an improved efficiency of 0.5% with an increased Jsc of 0.75 mA/cm2 when using a 20 nm thick WO3 layer on the SHJ solar cell. The results indicate that the WO3 layer can be a candidate to improve the efficiency of SHJ solar cells with a low fabrication cost. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the effects of aluminum oxide (Al2O3) antireflection coating (ARC) on silicon heterojunction (SHJ) solar cells. Comprehensive ARCs simulation with Al2O3/ITO/c-Si structure is carried out and the feasibility to improve the short circuit current density (JSC) is demonstrated. Based on the simulation results, we apply Al2O3 ARC on SHJ solar cells, and the increasement in JSC to 1.5 mA/cm2 is observed with an Al2O3 layer thickness of 20 nm. It is because the total reflectance of SHJ solar cells is decreased by the shifting of the wavelength range on constructive and destructive light interference. As a result, we believe that the proposed Al2O3 ARC can support an effective engineering technic to increase JSC and efficiency of SHJ solar cells. [ABSTRACT FROM AUTHOR]

Particle-bound pollutants are a critical risk factor for human respiratory/cardiovascular conditions. A comprehensive analysis of the physicochemical characteristics of PM is often challenging since it requires combining different practical methods with a good understanding the of characterization outputs. The present review aims to (1) provide a comprehensive assessment of the underlying mechanisms of PM cytotoxicity and the related biological response; (2) evaluate the selected methods for PM characterization in terms of outputs, technical aspects, challenges, and sample preparation; (3) present effective means of studying PM physicochemical toxicity and composition; and (4) provide recommendations for enhancing the human health risk assessment. The cellular response to potentially toxic elements in PM is complex to understand as exposure includes systemic inflammation, increased ROS accumulation, and oxidative stress. A comprehensive toxicity assessment requires blending morphological features and chemical composition data. For the morphological/chemical characterization, we recommend first using SEM-EDS as a practical method for the single-particle analysis. Then, the bulk chemistry of PM can be further studied using either a dry analysis (e.g., XRF) or wet analysis techniques (e.g., ICP and IC). Finally, when used on a need basis, the reviewed complementary laboratory methods may further add valuable information to the characterization. The accuracy of the human health risk assessment may be improved using bioaccessible/soluble fractions of the contaminants instead of the total contaminant concentration. Having an integrated understanding of the covered analytical methods along with the health risk assessment guidelines would contribute to research on atmospheric chemistry, molecular biology, and public health while helping researchers better characterize human exposure to PM and the associated adverse health effects. [ABSTRACT FROM AUTHOR]

Self-sensing concrete (SSC) has been vastly studied for its possibility to provide a cost-effective solution for structural health monitoring of concrete structures, rendering it very attractive in real-life applications. In this review paper, comprehensive information about the components of self-sensing concrete, dispersion methods and mix design, as well as the recent progress in the field of self-sensing concrete, has been provided. The information and recent research findings about self-sensing materials for smart composites, their properties, measurement of self-sensing signal and the behavior of self-sensing concrete under different loading conditions are included. Factors influencing the electrical resistance of self-sensitive concrete such as dry-wet cycle, ice formation and freeze thaw cycle and current frequency, etc., which were not covered by previous review papers on self-sensing concrete, are discussed in detail. Finally, major emphasis is placed on the application of self-sensing technology in existing and new structures. [ABSTRACT FROM AUTHOR]

The risk of a broad range of respiratory and heart diseases can be increased by widespread exposure to fine atmospheric particles on account of their capability to have a deep penetration into the blood streams and lung. Globally, studies conducted epidemiologically in Europe and elsewhere provided the evidence base indicating the major role of PM2.5 leading to more than four million deaths annually. Conventional approaches to simulate atmospheric transportation of particles having high dimensionality from both transport and chemical reaction process make exhaustive causal inference difficult. Alternative model reduction methods were adopted, specifically a data-driven directed graph representation, to deduce causal directionality and spatial embeddedness. An undirected correlation and a directed Granger causality network were established through utilizing PM2.5 concentrations in 14 United Kingdom cities for one year. To demonstrate both reduced-order cases, the United Kingdom was split up into two southern and northern connected city communities, with notable spatial embedding in summer and spring. It continued to reach stability to disturbances through the network trophic coherence parameter and by which winter was construed as the most considerable vulnerability. Thanks to our novel graph reduced modeling, we could represent high-dimensional knowledge in a causal inference and stability framework. [ABSTRACT FROM AUTHOR]

Military activities drastically affect soil properties mainly via physical/chemical disturbances during military training and warfare. The present paper aims to review (1) physical/chemical disturbances in soils following military activities, (2) approaches to characterization of contaminated military-impacted sites, and (3) advances in human health risk assessment for evaluating potential adverse impacts. A literature search mainly covering the period 2010–2020 but also including relevant selected papers published before 2010 was conducted. Selected studies (more than 160) were grouped as follows and then reviewed: ~40 on the presence of potentially toxic elements (PTEs), ~20 on energetic compounds (ECs) and chemical warfare agents (CWAs), ~40 on human health risk assessment, and generic limits/legislation, and ~60 supporting studies. Soil physical disturbances (e.g., compaction by military traffic) may drastically affect soil properties (e.g., hydraulic conductivity) causing environmental issues (e.g., increased erosion). Chemical disturbances are caused by the introduction of numerous PTEs, ECs, and CWAs and are of a wide nature. Available generic limits/legislation for these substances is limited, and their contents do not always overlap. Among numerous PTEs in military-impacted zones, Pb seems particularly problematic due to its high toxicity, abundance, and persistence. For ECs and CWAs, their highly variable physiochemical properties and biodegradability govern their specific distribution, environmental fate, and transport. Most site characterization includes proper spatial/vertical profiling, albeit without adequate consideration of contaminant speciation/fractionation. Human health risk assessment studies generally follow an agreed upon framework; however, the depth/adequacy of their use varies. Generic limits/legislation limited to a few countries do not always include all contaminants of concern, their content doesn't overlap, and scientific basis is not always clear. Thus, a comprehensive scientific framework covering a range of contaminants is needed. Overall, contaminant speciation, fractionation, and mobility have not been fully considered in numerous studies. Chemical speciation and bioaccessibility, which directly affect the results for risk characterization, should be properly integrated into risk assessment processes for accurate results. [ABSTRACT FROM AUTHOR]

Construction industry is very labor-intensive and one of the major sources of employment in the world. The industry is experiencing low productivity with minimum technological innovations for decades. In recent times, various automation technologies including 3D printing have received increasing interests in construction. 3D printing in construction is found to be very promising to automate the construction processes and have the potential of saving laborious work, material waste, construction time, risky operation for humans, etc. There has been a comprehensive body of research conducted to understand the recent advances, future prospects and challenges of large-scale adoption of 3D printing in construction projects. Being one the labor-intensive industries, this study also investigates the possible impact on the labor market with increasing adoption of 3D printing in construction. It is found that 3D printing can reduce significant number of labors which can solve the labor shortage problem, especially for the countries where construction is heavily dependent on immigrant workers. In contrast, 3D printing might not be favorable for the countries where construction is one of the main workforces and labor is less expensive. Moreover, 3D construction printing will also require people with special skills related to this new technology. [ABSTRACT FROM AUTHOR]

It is common to increase road capacity by constructing ring roads to reduce traffic congestion in city areas, although this is often found to be ineffective in the long run. Accordingly, this study investigates various traffic congestion management approaches and their effectiveness in major cities, and explores an identical transport problem in Almaty, Kazakhstan: The Big Almaty Ring Road (BAKAD). Several case examples from the existing literature are examined in which various approaches were taken for managing traffic congestion problems, and these approaches are classified into three concepts. The first concept comprises heavy engineering measures such as ring road development, new road construction, expansion of existing roads, etc. Such measures can initially reduce traffic congestion, but often become ineffective with time due to the generation of induced traffic. Many cities have taken Push and Pull measures that ensure more efficient use of existing capacity and have initiated environmentally friendly alternative transportation modes such as decreased car usage; promotion of public transport, biking and walking; minimization of the necessity of people's movement by changing urban land use patterns; and so on. These approaches have been found to be effective in providing sustainable transportation solutions and are classified as concept 2. Nevertheless, Push and Pull measures might not be enough for managing traffic congestion, and it might be necessary to increase the road capacity through heavy engineering measures, especially if the city experiences heavy transit traffic. This combined approach is categorized as concept 3. Consequently, the BAKAD project is examined under the umbrella of three concepts, and recommendations are provided based on the findings from the experience of different cities and interviews with experts from Almaty city. Both the results and recommendations developed are relevant for this specific case only, and are not necessarily transferable. [ABSTRACT FROM AUTHOR]

Like many other countries, the presence of wasteful activities is very common in Kazakhstan's construction industry. This severely affects the productivity of construction processes. Lean methodology maximizes the value of a process by minimizing wasteful or non-value adding (NVA) activities. This study aims to explore and quantify the impact NVA items on construction productivity. Several observations were made for construction processes in Astana, Kazakhstan to investigate and quantify various types of wasteful activities. Moreover, a survey was conducted to examine the general understanding of wasteful activities and Lean methods within the construction industry in Kazakhstan. In terms of wasteful activities, a similarity was found between the observed construction processes and survey results. Furthermore, apart from the commonly found seven types of wasteful activities, some other sources of waste, such as "preparation" and "break", were found from the observations. Finally, wasteful activities were mapped with commonly used Lean tools, as found in the literature, so that productivity can be improved by minimizing NVA activities. From the mapping and the survey results, value stream mapping (VSM) was found to be the most effective Lean tool, since it facilitates increased visualization. [ABSTRACT FROM AUTHOR]