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The hydrothermal treatment of Moroccan coal fly ash (CFA) in a basic medium leads to the selective formation of Na-X zeolite. By fusion with sodium hydroxide in the presence of CFA, the particles are transformed into sodium silicate and sodium aluminate, from which hydrothermal reaction favourably results in the production of a pure Na-X zeolite. A good crystallinity of Na-X zeolite was attained at NaOH:fly ash ratio of 1.2. Their high surface area and pore characteristics make the Na-X zeolite useful for the removal of the model anionic dye RY145 from water. The adsorption efficiency of the synthesised Na-X zeolite was evaluated and compared to raw CFA. Dye adsorption is more significant at acid pH, suggesting that the zeolite surface is positively charged. Kinetic and isotherm models applied to fit the experimental data reveal that the adsorption process is physisorption. It results that zeolite X is an efficient adsorbent for the extraction of dyes. [ABSTRACT FROM AUTHOR]

Several studies on solar cells using SCAPS-1D were conducted to investigate their performance, which are typically limited to I–V analysis for DC characterization. Therefore, in the present study, a very wide frequency range from 10–2 Hz to 1012 Hz was employed to explore diffusion processes and investigate the performance of lead-free Perovskite Solar Cells (PSCs) featuring as a novel heterostructure. These investigations concern the optimization of MASnI3 thickness as an absorber. Additionally, the impact of series (Rs) and shunt (Rsh) resistances is also examined. From the I–V analysis, it was determined that the power efficiency (PCE) could be achieved at a thickness of 0.6 µm. Increasing the series resistance (Rs) led to a significant decrease in the fill factor (FF) and (PCE), whereas the shunt resistance (Rsh) demonstrated a notable improvement in both (FF) and (PCE). Analysis of AC characteristics revealed complex impedance (Z*) and modulus (M*) indicative of main ionic transport, recombination, and diffusion processes crucial for optimization. An appropriate equivalent circuit model was developed and validated through deconvolution and theoretical considerations, yielding parameters such as the time constant for each process. It was observed that ionic conductivity and electronic diffusion play key roles in balancing charge collection and recombination losses. The critical influence of series and shunt resistance on low and high-frequency processes was emphasized, underscoring their significance in solar cell efficiency. A strong correlation was established between the evolution of time constants for each process and power conversion efficiency (PCE). [ABSTRACT FROM AUTHOR]

We investigated a three-dimensional semi-infinite spin-1/2 system bounded by a spin-1 surface using a Monte Carlo simulation based on the Metropolis algorithm. The exchange interactions and crystal field effects on phase diagrams, magnetizations, and susceptibilities were investigated. The phase diagrams in three planes were presented due to the competition between specific system parameters. The system demonstrated ordinary, extraordinary, surface, and special second-order phase transitions, as well as a surface first-order phase transition. Furthermore, tricritical and critical end-points were discovered. [ABSTRACT FROM AUTHOR]

Raw earth construction (RE) is an interesting alternative approach for reducing the use of conventional construction materials. The aim of this study is the stabilization of RE by a new organic binder manufactured based on algae. The stabilization is performed on the mortar scale as well as evaluated by conducting mechanical and thermal tests. Samples of mortar were manufactured based on local soil and Sargassum muticum type algae. The incorporation weight rates of algae are 0 (reference sample), 2, 4, 6, and 8 wt.%. Results showed that the compressive and bending strengths of algae mortar were improved by 77 and 70%, respectively. In addition, it was noticed that samples with 0.63 mm maximum grain size algae binder provide higher strengths in comparison with 0.80 mm maximum grain size algae binder. It was found also that 2 wt.% of incorporated algae provide similar mechanical resistance to 15 wt.% of slaked lime. The thermal investigation of samples showed three peaks: two endothermic peaks at 100 and 800 °C, which can be respectively attributed to the desorption of H2O and CO2 due to the decomposition of calcite; the third exothermic peak at 500 °C is attributed to the decomposition of the macromolecules of the algae. [ABSTRACT FROM AUTHOR]

This work aims to treat the raw effluents from a tannery using raw coal waste (fly ash and bottom ash) and bentonite clay as less expensive adsorbents and percolating agents. Their combination constitutes effective filters to retain heavy metals, dyes, and organic matter. After analysis of the raw wastewater, a significant pollutant load was detected; the chemical oxygen demand (COD) is around 3,400 mg·L–1, the biological oxygen demand about 240 mg·L–1 and suspended matter of 490 mg·L–1. These waters are also heavily loaded with heavy metals especially chromium with a high value of 981 mg·L–1, and they have an acidic pH of 4.2, which greatly exceed the specific limit discharges values, applicable to discharges from Moroccan tannery industries. Their treatment with fly ash, bottom ash, and bentonite clay leads to an almost complete elimination of Cr, Fe and Zn with a discoloration of 96% where the pH becomes neutral to slightly alkaline. The COD analysis gives an abatement rate of more than 72% while suspended matters are considerably reduced with a turbidity rate of 99%. Thus, the treated water can be used for irrigation or as wash water in industries. [ABSTRACT FROM AUTHOR]

In the current study, thin films of tin sulfide (SnS) were grown by sol–gel spin-coating technique deposited on glass substrates. The obtained thin films were characterized using X-ray diffraction (XRD), photoluminescence (PL) and UV–Vis spectrometer and the four point technique, respectively. The effect of annealing temperature on the SnS properties has been studied. The XRD results reveal that the films annealed at 500 °C have good crystalline quality with orthorhombic phase. Fourier-transform infrared spectroscopy (FTIR) spectra shows the Sn–S bond. The photoluminescence spectra showed two categories of band emission. The optical parameters (α, ε, n, k, Eg, and σop) were determined using UV–Vis spectroscopy. Moreover, the obtained results were compared to the theatricals results obtained with density functional theory (DFT) method using ab-initio approach. The optical and the electrical properties of the SnS Layers annealed at 400 °C and 500 °C offer the best possibility for their utilization in photovoltaic applications. [ABSTRACT FROM AUTHOR]

In this work, we study the Ising model with mixed spins S =  1/2 and S =  3/2 on the hypercubic lattice and the random crystal field at the sublattice with S = 3/2 described by a two peaks law. To achieve this, we use an approximation of position space renormalization group (PSRG) namely Migdal-Kadanoff in which we use both the free energy derivative and the flow in the parameter space of the Hamiltonian. For all values of the random probability, the critical behavior is determined via the critical exponents at the second-order fixed points while at low temperatures; the discontinuities of the of the free energy derivative provide the positions of the first-order transitions. The introduction of a minimal amount of disorder causes a change in the phase diagram showing the relevance of disorder for d = 2 and d = 3. The second-order transition remains always with the same critical exponents as those of the pure model, and a new first-order transition appears at very low temperature. Also, a comparison with other similar works is given. [ABSTRACT FROM AUTHOR]

A room-temperature nematic liquid crystal cell is prepared in the homeotropic geometry using dielectrically positive pentyl cyanobiphenyl. The indium tin oxide electrodes are treated to increase locally their surface resistance. At high frequencies (ω>ωc) the border of these regions behaves as capacitance edge, creating an oblique field which ‘‘writes.’’ At low frequencies (ω<ωc) the field is back normal to the electrodes and ‘‘erases’’ rapidly. A 50-μs erasing time has been achieved for E∼10 V/μm and ωc/2π=104 Hz. The practical smallest response time of the device is ∼(8ωc)-1. Sub-μs writing and erasing are possible. [ABSTRACT FROM AUTHOR]