rss_2.0Materials Sciences FeedSciendo RSS Feed for Materials Sciences Sciences Feed directly grown graphene-based solar cells<abstract> <title style='display:none'>Abstract</title> <p>Using plasma-enhanced chemical vapor deposition (PECVD) to directly grow graphene nanowalls (GNWs) on silicon to preparate the solar cells is compatible with current industrial production. However, many defects in the GNWs hinder improvement of the power conversion efficiency (PCE) of solar cells. In this work, we found that the defects in GNWs can be reduced under the condition of keeping the appropriate sheet resistance of GNWs by simultaneously reducing the growth temperature and increasing the growth time. Then, a PCE of 3.83% was achieved by minimizing the defects in the GNWs under the condition of ensuring adequate coverage of GNWs on bare planar silicon. The defects in GNWs were further reduced by adding a poly(3,4-ethylenedioxythiophene) (PEDOT):Nafion passivation coating, and the PCE was significantly improved to 10.55%. Our work provides an innovative path and a simple approach to minimize the defects in graphene grown directly on silicon for high-efficiency solar cells.</p> </abstract>ARTICLEtrue lighting systems and the method of implementing dynamically adjustable on-demand strategies – conclusions from research<abstract> <title style='display:none'>Abstract</title> <p>Street lighting is an important aspect of the operation of not just every city or municipality but also the operation of the roads and highways in every country. The search for energy-saving solutions has become a ubiquitous number-one topic and leads to the need for lighting management systems to make lighting more efficient and economical from a financial and environmental point of view. There are many important needs of cities and municipalities strictly connected with the type of roads and areas in cities and their surroundings. Highways, country roads, main city roads, parks, cycling paths and residential areas all have different requirements with regard to efficient lighting management. Lighting and power schedules, adaptive lighting schemes based on the density of road usage, dynamically adjustable on-demand lighting which lights up the way ahead of moving objects (vehicles or pedestrians). All of the above are important and can help in the achievement of the main goal, which is efficient energy usage properly managed for the given situation and which will ensure safety and comfortable lighting for all kinds of roads. This paper is focused on dynamically adjustable on-demand lighting, it proposes a solution capable of achieving optimal lighting management for cities and surrounding areas.</p> </abstract>ARTICLEtrue Extracts from L. As Ecological Additives in Soybean Seed Coating Applications<abstract> <title style='display:none'>Abstract</title> <p>This paper proposes a new biostimulant coating for soybean seeds. The aim of the study was to create a coating for <italic>Glycine max</italic> (L.) Merr. soybean seeds, using root infusion from <italic>Arctium lappa</italic> L. as a biostimulant component. The effectiveness of the produced coating was evaluated in a three-year field study. The analysis of the effectiveness of the developed coating was based on the evaluation of plant biometric traits and yield. The study showed that the designed and manufactured soybean seed coating based on the root infusion of <italic>Arctium lappa</italic> L. can be considered as a new agronomic strategy to improve the productivity of soybean <italic>Glicyne max</italic> (L.) Merr. under actual field conditions. The application of the biostimulant coating resulted in soybean plants with significantly increased biometric traits (plant height, height of the first pod set, number of pods per plant, number of seeds per pod) and productivity (yield improvement of more than 10%). Only a reduced weight of 1,000 seeds compared to control samples was noted.</p> </abstract>ARTICLEtrue Simulation of Soil Water Dynamics in Automated Drip Irrigated Okra Field Under Plastic Mulch<abstract> <title style='display:none'>Abstract</title> <p>In India, drip irrigation with plastic mulch is a common practise for irrigation that conserves water. For the design and administration of irrigation regimes, a thorough understanding of the distribution and flow of soil water in the root zone is required. It has been demonstrated that simulation models are effective tools for this purpose. In this work, an automated drip-irrigated Okra field with seven treatments namely T1- Soil moisture-based drip irrigation to 100% FC, T2- Soil moisture-based drip irrigation to 80% FC, T3- Soil moisture-based drip irrigation to 60% FC, T4- Timer based drip irrigation to 100% CWR, T5- Timer based drip irrigation to 80% CWR, T6- Timer based drip irrigation to 60% CWR and T7- Conventional drip irrigation at 100% CWR were utilised to mimic the temporal fluctuations in soil water content using the numerical model HYDRUS- 2D. With the help of the observed data, the inverse solution was used to optimise the soil hydraulic parameters. The model was used to forecast soil water content for seven field treatments at optimal conditions. Root mean square error (RMSE) and coefficient of determination (R2) were used to assess the congruences between the predictions and data. With RMSE ranging from 0.036 to 0.067 cm3 cm- 3, MAE ranging from 0.020 to 0.059, and R2 ranging from 0.848 to 0.959, the findings showed that the model fairly represented the differences in soil water content at all sites in seven treatments.</p> </abstract>ARTICLEtrue, microstructure, and machinability of aluminum metal-matrix composites<abstract> <title style='display:none'>Abstract</title> <p>Today, researchers across the world focus on sustainable products, and, accordingly, it is now imperative to develop sustainable MMCs. In line with this, ongoing experimental work aims to fabricate aluminum 6061 MMC with ground granulated blast furnace slag (GGBS) and study the micro-structural and machinability characteristics. A liquid state stir casting setup is used to melt aluminum 6061 alloy and reinforced with 2.5 wt.%, 5.0 wt.%, and 7.5 wt.% of GGBS. X-ray diffraction (XRD) studies were used to identify the chemical elements that were present in the fabricated samples. In order to observe the formation of any secondary elements, energy-dispersive X-ray spectroscopy and scanning electron microscopy (SEM) were utilized on the cast composites. Through the milling process, the influence of the GGBS reinforcement composition on the surface roughness (SR) and material removal rate (MRR) of aluminum 6061 MMC was examined, considering the parameters of spindle speed, feed rate, depth of cut, and reinforcement composition percentage. The L<sub>9</sub> orthogonal array (OA) was used to investigate the results of the experiments, and the Taguchi technique was used to optimize the process. The best MRR value was produced by the feed rate (B3) of 260 mm<sup>3</sup>/min and the depth of cut (C3) of 0.75 mm. The study ascertained that the lower SR value is attained corresponding to a spindle speed of 1,250 rpm, a feed rate of 220 mm<sup>3</sup>/min, a depth of cut of 0.25 mm, and a reinforcement composition percentage of Al 6061 with 5% GGBS.</p> </abstract>ARTICLEtrue possibilities of scanning acoustic microscopy in the assessment of explosive welding<abstract> <title style='display:none'>Abstract</title> <p>The last two decades have brought stable and impressive development accompanied by the industry acceptance of the use of high energy techniques based on energy obtained from explosive detonation energy. Such manufacturing processes are not only commercially viable, but also allow complex product shapes and unique combinations of metal sheets in terms of materials to be obtained; they enable the creation of composites which cannot be obtained by other conventional methods. Plated sheets are composed of a base material and a thinner plating material layer. An essential aspect in the validation of explosive welding is the quality control of joints made using this technology. The basic control methods are destructive tests – mainly metallographic, which reveal the microstructure at the connection boundary. Non-destructive tests, used in industrial practice, are classical, normalised ultrasonic tests of welding joints, conducted in accordance with ISO 17640:2017 and ISO 11666:2018 standards. Due to the relatively low thickness of the explosion-tested layers (2 mm and 3 mm single layers), which is the object of this study, assessing them using widely available ultrasonic techniques is limited. According to current scientific studies, the application of the scanning acoustic microscopy (SAM) is a prospective non-destructive method allowing for the qualitative and quantitative assessment of the continuity of the metallic connection on the contact surface of two materials. This paper presents the results of research on the quality of clads, welded explosively using a non-destructive research technique, namely SAM, verified with metallographic tests.</p> </abstract>ARTICLEtrue Analysis of Single Pile with Embedded Beam Row and Volume Pile Modeling under Seismic Load<abstract> <title style='display:none'>Abstract</title> <p>Indonesia is located between the Eurasian, Pacific, Philippines, and Indo-Australian plates. Various tectonic processes in the world and collisions between large plates and several small plates trigger many earthquakes in Indonesia. This study aimed to evaluate the response of bored piles in the Auditorium Building of Brawijaya University toward seismic loads through analytical and numerical approaches based on finite elements with 2D (embedded beam row) and 3D (volume pile) modeling, where the analysis approach of pile deformation and lateral resistance with numerical methods will depend on idealization of the model used. In addition, the lateral resistance was compared based on combination lateral loads, pile stiffness, and soil stiffness when the values were different. The 2D finite element analysis reduces lateral resistance but overestimated the deflection on the pile surface. This is because in the 2D finite element modeling with an embedded beam row that the friction factor represented by the spring can reduces the stiffness and the pile–soil is tangent, so that there is no slipping against each other. In addition, the 3D finite element analysis with volume pile modeling increases soil stiffness at greater depths and the friction factor (interface) can improve the interaction between the soil and pile.</p> </abstract>ARTICLEtrue and horizontal dynamic response of suction caisson foundations<abstract> <title style='display:none'>Abstract</title> <p>In this article, the dynamic response of suction caisson foundations is studied using a three-dimensional finite element model with an absorbing boundary. The adopted formulation is based on the substructuring method. This formulation has been applied to analyze the effect of soil–structure interaction on the dynamic response of the suction foundation as a function of the kind of load. The suction caisson foundations are embedded in viscoelastic homogenous soils and subjected to external harmonic forces. For each frequency, the dynamic impedance connects the applied forces to the resulting displacement. The constitutive elements of the system are modeled using the finite element volumes and shell elements. The numerical results for the dynamic response of the suction foundations are presented in terms of vertical and horizontal displacements as well as vertical and horizontal dynamic impedances. The results indicated that the overall dynamic response is highly affected by the suction caisson diameter, the soil stiffness variation, and the suction caisson length.</p> </abstract>ARTICLEtrue and ductility factors of XBF structures with pinned and fixed supports<abstract> <title style='display:none'>Abstract</title> <p>In today's time, most seismic design codes are based on a linear elastic force-based approach that includes the nonlinear response (ductility and overstrength) of the structure through a reduction factor (named behavior factor <italic>q</italic> in Eurocode 8 [EC8]). However, the use of a prescribed <italic>q</italic>-factor that is constant for a given structural system may fail in providing structures with the same risk level. This paper focuses on the estimation of actual values of <italic>q</italic>-factor for X-braced steel frames (XBFs) designed according to the European codes and comparing these values to those suggested in EC8. For this purpose, a nonlinear pushover analysis has been performed. The effects of specific parameters, such as the stories number, the brace slenderness ratio, the local response of structural members, and the support type, are evaluated. The results show that the most important parameter that affects the <italic>q</italic>-factor is the brace slenderness ratio, while the support type has less effect on this factor. Furthermore, a local strength criterion has been proposed to implicitly ensure that the suggested value of the <italic>q</italic>-factor is conservative.</p> </abstract>ARTICLEtrue the Effect of Environment Acidity on Stabilized Expansive Clay<abstract> <title style='display:none'>Abstract</title> <p>In this article, the effects of environmental acidity on the mechanical and volumetric properties of cement-stabilized clay soils have been investigated through various tests on experimental scale. In this study, a problematic clay was chemically stabilized by cement under three treatment conditions including short term, medium term, and long term with different conditions varying from acid to alkaline environments, which were tested by different methods to evaluate their mechanical and volumetric behavior and properties. Mechanical characteristics assessment tests in this study include compaction tests, and unconfined compressive strength, which was conducted on samples under different conditions in terms of acidity and treatment time. The results of the study indicated that soil improvement by cement increases the mechanical strength and decreases the rate of soil swelling over time and treatment duration. However, the degree of acidity of the environment affects the chemical reactions of soil and cement, especially cement hydration, which causes changes in soil strength and volume variation due to swelling.</p> </abstract>ARTICLEtrue On Energy-Efficient Alternative for Different Types of Traditional Soil Binders<abstract> <title style='display:none'>Abstract</title> <p>Due to urban sprawl, the demand for land has increased for the purpose of construction. It is unlikely that soil available at different construction sites will be suitable for designed structures. For improving the load-bearing capacity of the soil, different soil binders are used, which are present in distinct states. In this review, the authors have collected details about various binders, which are generally used in the soil stabilization, and their effect as a binding agent on the soil. In this article, the authors tried to review different traditional binders. After studying various research articles, the authors found that lime, ground-granulated blast slag (GGBS) polypropylene, polyurethane grouting, and asphalt mix are frequently used binders. However, the authors also gathered information about the negative environmental impact of these traditional soil binders, which led to the need for alternatives to these commonly used soil binders. To diminish this issue, different alternate hydraulic and non-hydraulic binders are discussed. The authors found alternatives to cement and lime with the alkali-activated material consisting of Na<sub>2</sub>O and silica modulus and belite-calcium sulfoaluminate ferrite, which is also known as “Aether™.” According to the research, both alternatives emit 20–30% less CO<sub>2</sub> into the environment and also improve the compressive strength of the soil. The various studies promotes bitumen modification. Incorporating 20-mesh crumb rubber and bio-oil into the bitumen reduces its viscosity and improves its fatigue value. When waste oil is mixed with asphalt, it revitalizes the bitumen, improves fatigue resistance, and increases compressive strength. The soil particles treated by Eko soil are held together by enzymes, which give them the same strength as cement. Apart from that, low-carbon binders such as basic oxygen furnace slag, bamboo fiber, enzyme-based soil treatment, zebu manure for stabilization, and lignin-contained biofuels and coproducts are discussed. Replacing these traditional binders helps with energy savings. All waste products are recycled, and energy is saved by not manufacturing traditional binders. Additionally, energy is saved, which is required to avoid the detrimental effects of these conventional binders, making them energy-efficient alternate binders. The authors also summarize the methods used, impacts, and changes that occur in soil properties after using substitutes in place of traditional binders. From the review, the authors determined that different binders have various properties in terms of chemical and physical compositions, and they show different variations in terms of strength when added to soil with low bearing capacity or poor stability.</p> </abstract>ARTICLEtrue of Set Accelerator on Capillary Suction and Porosity of Concrete – Cast Samples with Constant Water/Binder Ratio<abstract> <title style='display:none'>Abstract</title> <p>Alkali-free set accelerators are added at the nozzle to ensure rapid set of wet sprayed concrete. The accelerator affects the strength development, porosity and transport properties, and hence the durability, of the sprayed concrete. We developed a method to cast samples with varying set accelerator doses to measure the effect of the accelerator on porosity, but with a constant effective water/binder ratio of 0.45 for each accelerator dose. Six cylinders of concrete were cast with set accelerator doses of 0, 2, 4, 6, 8 and 10 % of effective binder mass. High workability was achieved to enable mixing before rapid stiffening occurred, though this high workability led to some aggregate settlement in the cylinders. Porosity was measured by capillary suction on dried specimens of hardened concrete and subsequent pressure saturation of macro pores (PF test). The samples cast with higher doses of set accelerator had higher suction porosities and higher rates of capillary suction. Using a modified Powers equation gave very low calculated degree of hydration values for concrete with set accelerator, indicating that the equation is not applicable for concrete with set accelerators, due to the higher suction porosity in accelerated matrices, caused by different hydration products.</p> </abstract>ARTICLEtrue Cement Paste Modified with Carbon Nanomaterials Capable of Self-Repair after a Fire?<abstract> <title style='display:none'>Abstract</title> <p>This manuscript presents preliminary results on the cement paste potential, with and without carbon nanomaterials, to heal high-temperature cracks. Cement paste beams were subjected to thermal loading of 200°C and 400°C after 28 days of water curing. High temperature caused the formation of microcrack networks on the specimen’s surface. Self-healing was achieved by exposing the cracked samples to cyclic water immersion. The efficiency of the process was evaluated based on the crack closure and mechanical properties recovery after 24 days. The results indicated a distinct dependence of the healing on the loading temperature. Carbon nanotubes had a positive effect on self-repair efficiency.</p> </abstract>ARTICLEtrue of High-Pressure Washing on Chloride Ingress in Concrete – Development of an Accelerated Test Method<abstract> <title style='display:none'>Abstract</title> <p>Bridges constitute an important part of the infrastructure. For bridges to have the longest possible service life with minimum repairs, the maintenance is of great importance. One type of bridge maintenance that is rarely researched is the continuous preventive maintenance. The continuous preventive maintenance consists of removal of vegetation, cleaning of bridge joints and drainage systems as well as high-pressure washing of the structure. The effect of washing is discussed but not properly researched. A study on the effectiveness of high-pressure washing on concrete is therefore being conducted. An accelerated test method is being developed to mimic field testing. The method has been developed through tests on small concrete specimens subjected to fluctuating temperature, fluctuating moisture, and repeatable exposure to de-icing salt during several cycles. The specimens are of two recipes where one represents an old concrete bridge with rather high water-cement ratio (0.6) and the other one represents a new concrete bridge with a low water-cement ratio (0.4). The first two versions of the method are described. The second version shows promising results, but the method needs further development to incorporate additional factors.</p> </abstract>ARTICLEtrue of Crushed Fine Materials<abstract> <title style='display:none'>Abstract</title> <p>As natural resources of sand and fine material used in the concrete industry are becoming more scarce, crushed materials are being used to a greater extent. Shape and texture of machine crushed materials differ from aggregates naturally ground, layered and sorted under the course of millions of years. It is assumed that crushed aggregates are more angular and of less smooth texture than natural aggregates, which will affect the flow behaviour of a suspension containing crushed material. In the mix design process of cementitous suspensions, an adequate rheology of the micro mortar (all constituents in the concrete being able to pass a 0.125 mm sieve, including the cement) is crucial. In this paper, the shape of fine particles is linked to the micro mortar plastic viscosity of the filler suspension including cement. The plastic viscosity here serves as an important quality assessment of the filler, since the micro mortar workability features are vital for the final mix design quality of the concrete workability.</p> </abstract>ARTICLEtrue Modelling of Lithium Mitigation for Alkali-Silica Reactivity<abstract> <title style='display:none'>Abstract</title> <p>The Alkali-Silica Reaction (ASR) is a deleterious concrete chemical reaction that has been studied a lot since its discovery in 1940. The reaction produces a highly hygroscopic silica gel that swells into the pores of concrete, resulting in the critical decrease of the mechanical performances of the affected structures. Some methods have been investigated to limit expansion under a certain limit, among them lithium mitigation. However, the mechanisms are not really understood yet and determining the right amount of lithium is still arduous. An attempt for a method in coherence with experience is presented in this study, using the chemo-mechanical model of Larive and curve-fitting. The results provide accuracy to experimental measurements from several protocols, and call for further research.</p> </abstract>ARTICLEtrue Mechanisms of Fibre Reinforced Shotcrete: Numerical Simulations Considering Local Variations in Thickness and Bond Strength<abstract> <title style='display:none'>Abstract</title> <p>Fibre-reinforced shotcrete is the most common support method for hard rock tunnels in the Nordic countries. The design of shotcrete is often based on empirical methods or simplified analytical equations, which neglect variations in mechanical properties and shotcrete thickness. Data collected from the field shows that significant variations in shotcrete thickness and bond strength should be expected during tunnel construction. However, how this affects the structural behaviour and capacity of the shotcrete lining is unknown. Moreover, the design philosophy for shotcrete assumes that the primary failure modes of shotcrete, i.e. bond and flexural failure, can be treated separately. This was derived based on observations of experiments in a laboratory environment. Therefore, the focus of a finalized doctoral project was to develop a numerical framework to simulate the structural behaviour of fibre-reinforced shotcrete in interaction with hard rock and rock bolts. The effect of variations in shotcrete thickness and bond strength was studied through numerical simulations to increase the understanding of its effect on the failure load of the lining. The results indicate that the most important parameter is the mean value of the shotcrete thickness and bond strength around a narrow perimeter of the block.’</p> </abstract>ARTICLEtrue (PES) Membrane on Agar Plates as a Plant Growth Platform for Spaceflight<abstract> <title style='display:none'>Abstract</title> <p>Plant biology experiments in microgravity face many challenges, among which are the constraints of the growth platforms available on the International Space Station (ISS). Protocols for preservation and sample return to Earth often limit efficient dissection of seedlings for downstream tissue-specific analysis. The Advanced Plant Experiment (APEx)-07 spaceflight experiment required a large quantity of dissectible, well-preserved seedlings suitable for omics analysis. During preflight tests, protocols were developed for using an agar-polyethersulfone (PES) membrane platform for seedling growth that allowed for seedling germination and growth aboard the ISS and rapid freezing to provide intact seedlings for dissection and extraction of high-quality DNA, RNA, and protein. Each component of the growth setup was carefully examined: membrane color, hydration and growth substrate, capacity for delayed germination, growth duration, harvest approach, and preservation pipelines were all individually optimized. Sterilized Arabidopsis seeds were adhered to PES membrane with guar gum. Membranes were laid onto 0.8% agar containing 0.5x Murashige and Skoog (MS) in 10 cm square Petri dishes and held at 4 °C until the experiment was actuated by placing the Petri dishes at room temperature. Seedlings were grown vertically for 12 days. PES membranes were removed from the agar, placed in the Petri dish lid, wrapped in foil, and frozen at −80 °C. Seedlings were dissected into roots and shoots and provided high-quality DNA, RNA, and protein. The system is simple, potentially adaptable for seedlings of multiple species, scalable and cost effective, and offers added versatility to existing ISS plant growth capabilities.</p> </abstract>ARTICLEtrue of air plasma spraying process parameters on the thermal barrier coating deposited with micro- and nanopowders<abstract> <title style='display:none'>Abstract</title> <p>This study investigates the optimal conditions to deposit a thermal barrier coating using micro- and nanopowders in the air plasma spraying (APS) process. The influence of the APS process parameters on the thickness, porosity and hardness of the yttria-stabilized zirconia (YSZ; ZrO<sub>2</sub> × 8Y<sub>2</sub>O<sub>3</sub>) coatings deposited with a single-electrode plasma gun was determined. The temperature and velocity of melted particles were determined by the DPV diagnostic system to decrease the number of experimental processes. The current and H<sub>2</sub> flow rate were changed in this research. Metco-6700 YSZ micropowder has already been used in plasma spray physical vapor deposition. The results of this study suggest the possibility of using it for APS. The particles of this powder are characterized by high temperature (2,700°C–2,900°C) and high speed (&gt;380 m/s). The highest thickness of the coating was obtained with 6 NLPM (normal liter per minute) H<sub>2</sub> flow and 800 A current. Difficulties were observed with the feeding of the powder particles at higher H<sub>2</sub> flow. The results showed that using APS, deposition of Metco-6609, a nanopowder normally used in suspension plasma spraying, is possible. In this research, this powder was fed using a carrier gas. The coatings were around 40 μm thick and had high porosity. The lowest porosity of the coating was obtained at a current of 600 A and H<sub>2</sub> flow rate of 12 NLPM. In the coatings, unmelted spherical particles were also visible.</p> </abstract>ARTICLEtrue