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High-performance fibre-reinforced polymer (FRP) composites offer outstanding specific strength and stiffness. However, their inherent brittleness can result in sudden and catastrophic ...failure without adequate warning, making them unsuitable for many applications. To overcome this limitation, we developed graphene-based glass-carbon FRP hybrid composites with excellent pseudo-ductile properties. Our method involves coating glass and carbon fibre fabrics with graphene-based materials using a scalable pad-dry-cure technique, followed by epoxy matrix reinforcement via vacuum-assisted resin infusion (VARI). Tensile and flexural tests reveal remarkable pseudo-ductile behaviour, with 1 wt% GNP-coated composites showing approximately ∼ 17.05 % higher Young's modulus, ∼18.52 % higher ultimate failure stress, and ∼ 31.73 % higher strain% compared to glass-carbon/epoxy hybrids. By enabling the manufacture of high-performance pseudo-ductile composites at scale using a cost-effective manufacturing method, these composites hold significant potential for next-generation applications.
In order to reduce the CO2 associated with cement production, this study explored the potential of rice husk ash (RHA) and fly ash (FA) as supplementary cementitios materials for partially replacing ...cement in concrete production. The study aimed to analyze the synergistic effects of a cement-based mixture consisting of RHA and FA in different proportions on concrete's fresh, hardened, non-destructive and microscopic properties. In addition to the experimental work, this study successfully applied machine learning to predict the compressive strength of RHA-FA concrete using three types of algorithms: ANN (Analytical Neural Network), XGB (Extreme Gradient Boosting), and GBM (Gradient Boosting Model). A total of 138 data points were used for this prediction, and statistical and parametric analyses were performed to define the impact of input parameters on the outcome. Furthermore, both destructive and non-destructive tests were conducted on hardened concrete, including compressive strength, split tensile strength, ultrasonic pulse velocity (UPV), and rebound hammer. The scanning electron microscope (SEM) was operated to analyze the microstructural characteristics of concrete. The compressive and split-tensile strength test results showed that the mixture with a higher percentage of fly ash and a lower percentage of rice husk ash achieved maximum strength. The X-ray Fluorescence (XRF) analysis revealed that both ashes contained a significant amount of silica, which gave them excellent pozzolanic properties. After 28 days, both the UPV and the rebound hammer strength align with the destructive compressive strength results. The study also employed SHAP (SHapley Additive exPlanations) and PDP (Partial Dependence Plot) analyses to identify the optimal range for each parameter's contribution to strength improvement. The machine learning models exhibited a strong correlation with the test results, achieving an R2 value of 0.84 for the XGBoost model.
COVID-19 is caused by the SARS-CoV-2 virus, which is mainly transmitted directly between humans. However, it is observed that this disease can also be transmitted through an indirect route via ...environmental fomites. The development of appropriate and effective vaccines has allowed us to target and anticipate herd immunity. Understanding of the transmission dynamics and the persistence of the virus on environmental fomites and their resistive role on indirect transmission of the virus is an important scientific and public health challenge because it is essential to consider all possible transmission routes and route specific transmission strength to accurately quantify the herd immunity threshold. In this paper, we present a mathematical model that considers both direct and indirect transmission modes. Our analysis focuses on establishing the disease invasion threshold, investigating its sensitivity to both transmission routes and isolate route-specific transmission rate. Using the tau-leap algorithm, we perform a stochastic model simulation to address the invasion potential of both transmission routes. Our analysis shows that direct transmission has a higher invasion potential than that of the indirect transmission. As a proof of this concept, we fitted our model with early epidemic data from several countries to uniquely estimate the reproduction numbers associated with direct and indirect transmission upon confirming the identifiability of the parameters. As the indirect transmission possess lower invasion potential than direct transmission, proper estimation and necessary steps toward mitigating it would help reduce vaccination requirement.
Abstract
This paper describes the fabrication process and characteristics of dimension- and position-controlled gallium nitride (GaN) microstructure arrays grown on graphene films and their quantum ...structures for use in flexible light-emitting device applications. The characteristics of dimension- and position-controlled growth, which is crucial to fabricate high-performance electronic and optoelectronic devices, were investigated using scanning and transmission electron microscopes and power-dependent photoluminescence spectroscopy measurements. Among the GaN microstructures, GaN microrods exhibited excellent photoluminescence characteristics including room-temperature stimulated emission, which is especially useful for optoelectronic device applications. As one of the device applications of the position-controlled GaN microrod arrays, we fabricated light-emitting diodes (LEDs) by heteroepitaxially growing In
x
Ga
1−x
N/GaN multiple quantum wells (MQWs) and a
p
-type GaN layer on the surfaces of GaN microrods and by depositing Ti/Au and Ni/Au metal layers to prepare n-type and p-type ohmic contacts, respectively. Furthermore, the GaN microrod LED arrays were transferred onto Cu foil by using the chemical lift-off method. Even after being transferred onto the flexible Cu foil substrate, the microrod LEDs exhibited strong emission of visible blue light. The proposed method to enable the dimension- and position-controlled growth of GaN microstructures on graphene films can likely be used to fabricate other high-quality flexible inorganic semiconductor devices such as micro-LED displays with an ultrahigh resolution.
This paper reports an investigation of the mechanical and microscopic properties of partially replaced banana leaf ash (BLA) concrete. In this research, the cement was partially replaced by BLA in ...two phases: Phase A (0%, 5%, 10%, 15%, 20%, 25% and 30%) and Phase B (0%, 10%, 20% and 30%). The consequence of partially replacing cement with BLA in concrete was investigated by the application of a range of tests, namely X-ray fluorescence (XRF), compressive strength, splitting tensile strength, flexure strength, ultrasonic pulse velocity and scanning electron microscopy (SEM) analysis. The properties were then correlated with the properties of a standard 100% Portland cement concrete of similar strength. The XRF result of the BLA identified a composition with 48.93% SiO
and 3.48% Al
O
which indicates that the material potentially possesses pozzolanic properties. The mechanical properties of the partially replaced BLA concrete noted minor strength loss, approximately 5% with 20% partial replacement. The nondestructive testing data showed enhanced performance up to 20% partial replacement, with ultrasonic pulse values above 3500 m/s. The scanning electron microscopy analysis illustrated that the morphology of BLA specimens contained increased microcracks compared with the control. The decrease in strength observed is attributed to the fibrous composition of the BLA. The mechanical, nondestructive testing and microscopic results highlight the potential to utilize BLA as a partial replacement for cement as a pozzolanic material in concrete at up to 20% by weight of cement.
A diagnostic framework is proposed to assess the influence of star rating improvement for residential buildings on life cycle environmental impacts and life cycle costs (LCEI and LCC) using life ...cycle assessment (LCA) and life cycle costing methods, respectively, on all life cycle phases (i.e., construction, operation, maintenance, and disposal). A reference house was modified on the basis of six alternative designs to deliver a particular star rating in order to demonstrate the analysis framework. Two LCIA methods (i.e., material flows/add masses and eco-indicator 99 Australian substances) were used to estimate ten LCEI indicators under two categories: seven from problem-oriented (i.e., raw material, air emission, water emission, eco-toxicity, acidification/eutrophication potential, ozone depletion, and climate change) and three from damage-oriented (i.e., resource depletion, ecosystem quality, and effect on human health) categories. The three damage-oriented indicators were combined to evaluate environmental and economic wellbeing on a single eco-point basis. All these combinations of impact indicators can offer three lines of analytical options along with star rating: problem-oriented, damage-oriented, and a variety of problem and damage-oriented LCEIs with LCCs. Hence, the optimum house selection is-based not only on cost or star rating, but also on LCEIs.
•Hermetic storage of paddy to produce good quality storage products.•Smart monitoring of temperature and relative humidity of hermetic storage technology.•IoT based low-cost remote control monitoring ...system to reduce postharvest losses of paddy.•Smart monitoring system replaced continuous manual monitoring and inspection.
In Bangladesh, where agriculture forms the backbone of the economy, efficient grain storage is crucial, particularly for paddy storage. Traditional methods like gunny bags and plastic containers are common, but the recent introduction of hermetic storage technologies, such as GrainPro bags and hermetic cocoons, have significantly reduced postharvest losses paddy. However, most research focuses on oxygen (O2) and carbon dioxide (CO2) levels in those open storage systems. This study introduces an innovative, cost-effective remote monitoring system for hermetically sealed grain storage, designed using locally sourced components, including a Digital Hygrometer, WiFi Mini IP Camera, and a Remote Controller unit. Tested over a 125-day period at Advanced Storage Lab, Bangladesh Agricultural University, the system effectively monitored the internal environment of the storage units. Key findings show that the internal temperature of the storage bags varied between 16.7°C and 29.2°C, demonstrating lesser fluctuation compared to the ambient temperature range of 16.1°C to 33.5°C. The relative humidity inside the storage units remained stable between 45 % and 54 %, in contrast to the external humidity range of 45 % to 81.2 %. Additionally, using the Steffe and Singh equation, an increase of 0.512 % in Equilibrium Moisture Content (EMC) of paddy was recorded. Notably, there was no evidence of insect or mold growth after 125 days of storage. This study's remote monitoring system not only marks a significant advancement in hermetic grain storage technology but also contributes to sustainable agricultural practices. It provides a practical, real-time solution to monitor and manage key environmental parameters, ensuring the preservation of grain quality over time.
In this work, the light trapping prowess of photonic crystal fiber (PCF) is used to propose an overly sensitive dual arrow shaped and dual plasmonic material compatible (DPMC) surface plasmon ...resonance (SPR) sensor. We have used gold (Au) and titanium nitride (TiN) as the plasmonic material on different occasions to proceed during the investigation. The finite element method is utilized to investigate the performance of the surface plasmons with the aid of the COMSOL 5.3 software, having a circular, perfectly matched layer. Maximum sensitivities for wavelength (WS) and amplitude (AS) were obtained about 31,000 nm/RIU and 3629 RIU
−1
, respectively, having a sensor resolution of 3.23 × 10
–6
RIU with a maximum FOM of 1033 for Au. TiN shows a maximum AS of 591 RIU
−1
, a maximum WS of 67,000 nm/RIU with a resolution of 1.50 × 10
–6
RIU and a maximum FOM of 593. The refractive index (RI) range for the target analytes is observed between 1.35 and 1.42. By carefully selecting the plasmonic material, both the advantages of higher AS and WS can be obtained by the same design. According to our knowledge, this paper is the first one where analysis were performed on the same model using two plasmonic materials yielding a very high WS of 67,000 nm/RIU and AS of 3629 RIU
−1
. With its simplistic construction and appropriate sensitivity, the proposed DPMC-SPR-PCF sensor has potential applications in detecting biomolecules, chemical, and biological analytes.
Natural fiber reinforced composites (FRC) are of great interests, because of their biodegradability, recyclability, and environmental benefits over synthetic FRC. Natural jute FRC could provide an ...environmentally sustainable, light weight, and cost-effective alternative to synthetic FRC. However, the application of natural jute FRC is limited because of their poor mechanical and interfacial properties. Graphene and its derivatives could potentially be applied to modify jute fiber surface for manufacturing natural FRC with excellent mechanical properties, and lower environmental impacts. Here, we review the physical and chemical treatments, and graphene-based modifications of jute fibers, and their effect on mechanical properties of jute FRC. We introduce jute fiber structure, chemical compositions, and their potential applications first. We then provide an overview of various surface treatments used to improve mechanical properties of jute FRC. We discuss and compare various graphene derivative-based surface modifications of jute fibers, and their impact on the performance of FRC. Finally, we provide our future perspective on graphene-based jute fibers research to enable next generation strong and sustainable FRC for high performance engineering applications without conferring environmental problems.
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Materials science; Mechanical processing; Nanotechnology fabrication
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