Buein Zahra Technical University

ABSTRACT Isinglass/agar hydrogel beads were synthesized using a self‐assembly method at a water‐in‐oil emulsion interface. The hydrogel was chemically crosslinked using glutaraldehyde to generate stable aldimine bonds with amino (–NH 2 ) groups present in isinglass. Fourier‐transform infrared spectroscopy (FTIR) was utilized to determine the generation of chemical crosslinks within the hydrogel. The hydrogel's porous and interconnected three‐dimensional morphology was investigated with field emission scanning electron microscopy (FE‐SEM). The resulting hydrogel beads demonstrated a narrow and uniform size distribution ranging from 3.5 to 3.75 mm, confirming the reproducibility of the synthesis method. The equilibrium swelling ratio was reduced as the crosslinking agent concentration increased, resulting in water uptake decreasing from about 1358% to 753%. Also, the swelling ratio was very sensitive to pH changes, showing a maximum (~1580%) at pH 3 and decreasing as pH increased. The swelling ratio increased with the temperature, reaching approximately 1960% at 60°C. Analysis of the swelling kinetics showed that the swelling behavior was in good agreement with the pseudo‐second‐order model, implying the presence of chemical interactions between the polymeric chains and the molecules of water. These findings suggest that these hydrogels could be suitable for wastewater treatment, contaminant removal, or controlled release.

This study evaluates CO 2 -induced carbonate minerals synthesised by direct CO 2 absorption, as novel injectable materials for permeation grouting, aiming to enhance the sustainability of ground improvement techniques. The investigation started with Scanning Electron Microscopy (SEM), and X-ray Diffraction (XRD) analyses that attested the formation of siderite (FeCO 3 ) and calcite (CaCO 3 ) carbonate minerals, which precipitated in the soil voids. Sand samples treated with siderite grout achieved the highest Unconfined Compressive Strength (UCS) of 70 kPa at 11 % siderite content; those treated with calcite grout reached 53 kPa at a calcite content of 16 %. Peat, of a 12 kPa UCS, reached a UCS of 36 kPa after grouting with 20 % siderite, and 23 kPa after grouting with 19 % calcite. Life Cycle Assessment (LCA) of carbonate grout mixtures against conventional cement-based grout showed an 85 %–87 % reduction in the global warming potential and improvements in 13–14 out of the 18 environmental impact categories respectively for calcite and siderite grout, with major reductions in fossil and mineral resource scarcity, ground level ozone and fine particle formation. The proposed carbonate-based grouts comply with green chemistry principles and SDGs and have the potential advantage of consuming captured CO 2 from industrial sources. Overall, carbonate minerals synthesised using CO 2 give promise for grouting applications, while providing a potential route for CO 2 utilisation. • CO 2 -induced carbonate minerals were studied as alternatives to cement-based grouts. • XRD and SEM analyses attested the formation of siderite (FeCO 3 ) and calcite (CaCO 3 ). • FeCO 3 grouts show finer crystals and higher unconfined compressive strengths. • Synthesised CaCO 3 and FeCO 3 grouts reduce GWP by ∼85–87 % vs cement. • Life cycle trade-offs include higher water use and stratospheric ozone depletion.

The primary objective of this study is to demonstrate the effectiveness of the radial basis function partition of unity collocation method (RBF-PUM) for solving the fractional Rayleigh-Stokes problem in two dimensions. The time-fractional derivative is formulated in the Riemann–Liouville sense. Initially, the time-fractional derivatives in the governing equation are discretized, followed by the application of RBF-PUM to approximate the spatial derivatives. This method offers notable advantages, including local adaptivity and the ability to adjust node density within each partition. These features help mitigate the ill-conditioning commonly encountered in traditional RBF-based methods. The unconditional stability and convergence of the time-discrete scheme are established using the energy method. To validate the theoretical findings and illustrate the efficiency of RBF-PUM, two numerical experiments are conducted on regular and irregular 2D domains, alongside comparative numerical tests.

The original version of this Article contained an error in the graph and its associated numerical values, As the result of this error, in the Discussions section, under the subheading 'Porosity percentage' , "Considering Fig. 3, BET curve displays that the surface area of the sample covered with NB4-2 Nanoclay (double spray of 4% Nano-Bentonite solution) is equal to 18.57 square meters per gram, the volume of the holes is 0.062 cubic centimeters per gram, and the average size of the holes is equal to 13.37 nm.BJH curve also shows that most of the holes are less than 1.1 nm." now reads: "Considering Fig. 3, BET curve displays that the surface area of the sample covered with NB4-2 Nanoclay (double spray of 4% Nano-Bentonite solution) is equal to 18.67 square meters per gram, the volume of the holes is 0.064 cubic centimeters per gram, and the average size of the holes is equal to 13.91 nm.BJH curve also shows that most of the holes are less than 1.85 nm." Consequently, Figure 3 has been corrected.The original Figure 3 and its accompanying legend appear below.

Pandemics present major challenges not only to public health, but also to economies and the environment. While the direct health consequences of pandemics are well recognized, their indirect impacts on essential infrastructure, like wastewater systems, are less explored. This study examines the intricate connections between pandemics and wastewater management to develop effective mitigation strategies. A qualitative analysis of existing research highlights significant difficulties wastewater utilities face during pandemics, including increased wastewater volume, changes in wastewater composition, operational pressures, staff shortages, and disruptions in the supply chain. The most pronounced issues are the heightened volume and altered composition of wastewater, which can overwhelm treatment facilities, degrade effluent quality, and heighten pathogen transmission risks. Furthermore, operational pressures and staffing issues can hinder treatment effectiveness and maintenance, worsening environmental and health dangers. To tackle these challenges and bolster the resilience of wastewater systems during pandemics, strategies such as capacity planning, infrastructure enhancements, operational preparedness, data-driven approaches, and improved environmental protections are crucial. These strategies encompass anticipating demand, upgrading infrastructure, ensuring staff safety, leveraging wastewater-based epidemiology for decision-making, and enhancing disinfection protocols, ultimately enabling communities to create more robust and sustainable wastewater management systems.

In this research work, the effects of mechanical alloying and subsequent compaction by ECAP on the microstructural, physical, and mechanical properties of Al-ZrB2 metal matrix composites (MMCs) were evaluated. To prepare composite powders, a mixture of Al and ZrB2 particles was mechanically alloyed at various times of 1, 6, 12, 18 and 24 h. SEM micrographs indicate that the size of the obtained particles decreases by increasing the time of mechanical alloying up to 18 h. However, after this time, increasing the time of mechanical alloying has led to an increase in the size of the particles. By means of mechanical alloying for 18 h, the average size of fine particles reached 823 nm, while coarse particles were 8 μm. The calculation via the use of XRD examination implies that the mean crystallite size of powder decreased from about 68 nm to 31 nm and 26.8 nm, for Al and Al-5%ZrB2 samples, respectively, while lattice strain increased from 0.25% to 0.64% and from 0.3% to 0.73% after 1 h to 24 h milling of same samples, respectively. However, the rate of crystallite size reduction after 12 h of mechanical alloying is gradually reduced, and that is reached its lowest level after 18 h. After that, increasing the time of mechanical alloying has led to a saturation in the lattice strain. In continue, the resulting composite powder was heated, consolidated and turned into bulk material by warm equal channel angular pressing (ECAP) at the temperature of 250 °C. The resultant optimum composite has been characterized by EDS elemental mapping. Microhardness measurements and shear punch tests were performed to evaluate the mechanical properties of the unreinforced and composite samples after the ECAP process. The Al-ZrB2 MMC bulk samples subjected to ECAP, with a ZrB2 amount of 5 wt%, had a relative density, hardness, and ultimate shear strength of 99.3%, 170 HV, and 151 MPa, respectively, using powders which have been mechanically alloyed up to 24 h.

Potential competing interests: No potential competing

In this paper, a 5000 kW grid-connected photovoltaic system of Haft-Hoze Natural Park, 7 km southeast of Mashhad City, has been designed and simulated. This power plant is for two monofacial and bifacial systems in both fixed and tilted planes and trackers modes in PVSYST software. It is simulated and designed and the simulation data is compared in both cases. In this paper, the effect of temperature on solar panel performance is investigated first. This work has been done in three stages. At first, by keeping the solar radiation constant, the effect of temperature on the output performance of the panel. In the next step, the P-V curves at different ambient temperatures and changes in solar radiation have been investigated. In the following, it shows the effect of PV panel temperature on PV panel output performance at different intensities of solar radiation. The simulation results of the 5000 kW solar power plant, in a fixed tilted plane for the monofacial system, energy injected into the grid and performance ratio are 8291 MWh and 0.850. The bifacial system, energy injected into the grid, and performance ratio are 8730 MWh and 0.896. In the Trackers mode, for the monofacial system, energy injected to the grid and performance ratio are 9558 MWh and 0.838. For the bifacial system, energy injected into the grid and performance ratio are 10025 MWh and 0.880.