Magnetochemistry, Volume 8, Issue 11 (November 2022) – 25 articles

In this study, the effect of molarity on the structural, magnetic, and heat dissipation properties of magnetite nanoparticles (MNPs) was investigated to optimise the parameters for potential application in magnetic hyperthermia therapy (MHT). MHT works based on the principle of local temperature rise at the tumour site by magnetic iron oxide nanoparticles (MIONPs) with the application of an alternating magnetic field. MHT is a safe method for cancer treatment and has minimal or no side effects. Magnetite (Fe₃O₄) is the best material among MIONPs to be applied in local MHT due to its biocompatibility and high saturation magnetisation value. MNPs were prepared by co-precipitation at varying molarity. Structural characterisation was performed via X-ray powder diffraction (XRD) for crystalline structure analysis and field-emission scanning electron microscopy (FESEM) for morphology and particle size analysis. Measurement of the magnetic properties of the as-synthesised MNPs was carried out using a vibrating sample magnetometer (VSM). Power loss (P) was determined theoretically. The increase in molarity resulted in significant effects on the structural, magnetic, and heat dissipation properties of MNPs. The particle size and saturation magnetisation (M_s) decreased with the gradual addition of base but increased, together with crystallinity, with the gradual addition of iron source. M3 recorded the smallest crystalline size at 3.559 nm. The sample with the highest molarity (M4) displayed the highest heat generation capacity with a p value of up to 0.4056 W/g. High p values at the nano-scale are crucial, especially in local MHT, for effective heat generation, thus proving the importance of molarity as a vital parameter during MNP synthesis. Full article

The results of the synthesis of PAN(polyacrylonitrile)-magnetite composite fibers using the electrospinning method are presented. The electrospinning installation included a rotating drum collector for collecting fibers. Magnetite nanoparticles were synthesized using chemical condensation from an iron chloride solution. It was shown that homogeneous Fe₃O₄ magnetite nanoparticles with particle sizes of 6–16 nm could be synthesized using this method. Magnetite nanoparticles were investigated using X-ray diffraction analyses and transmission electron microscopy. Based on magnetite nanoparticles, composite PAN/magnetite fibers were obtained through electrospinning. The obtained composite fibers were investigated using scanning electron microscopy, X-ray diffraction analyses, and elemental analyses. It was shown that the magnetite nanoparticles were uniformly distributed on the surface of the fibers. A comparison of PAN fibers without any added magnetite to PAN/magnetite fibers showed that the addition of magnetite led to a decrease in the value of the fiber diameter at the same polymer concentration and under the same electrospinning process conditions. Full article

The magnetic stray field is an unavoidable consequence of magnetic multilayers, which may have a significant influence on the performance of spintronic devices. Based on Maxwell’s magnetostatics theory, here we numerically calculated the distributions of magnetic stray fields and self-demagnetizing fields in a series of patterned multilayer thin-film structures with either an in-plane or a perpendicularly magnetized ferromagnetic layer. The stray field above the ferromagnetic layer is inhomogeneous, showing the dramatic changes near the sample edge, but the uniformity in the center region could be improved with the increasing sample size. The stray field strength tends to zero for large samples, increases with the increase in the hard-layer thickness, and decreases with the increase in the distance D away from the ferromagnetic layer. In the multilayer samples, the separately simulated stray field and self-demagnetizing field within the soft layer agree well with the classic magnetostatic relationship of $B={\mu }_0\left(H_d+M\right)$. For the in-plane magnetized trilayer sample, the magnetic-flux density within the soft ferromagnetic layer slightly decreases in the antiparallel magnetization alignment and increases in the parallel alignment state with the increase in the intermediate non-magnetic-layer thickness. In contrast, for the sample with the perpendicular magnetization, the magnetic-flux density decreases as the non-magnetic layer is thickened for both the antiparallel and parallel state. This study may provide a theoretical basis for the design of thin-film spintronic devices. Full article

We present a theoretical study of the substrate influence on the electrical and magnetic properties of a one-dimensional multiferroic. We used a one-dimensional axial next-nearest neighbor Ising model (1D ANNNI model). The effect of the substrate was modeled using the periodic Frenkel–Kontorova potential. It is shown that the periodic potential of the substrate reduces the polarization of the multiferroic at low temperatures. The substrate potential significantly affects the structural changes near the magnetic phase transition temperature. Full article

In the inverse problem, the traditional way to obtain a stable solution is based on the maximum smoothness criteria. However, this approach cannot generate clearer and more focused images. In this study, we propose an improved inversion method based on the smoothness constraints. In the algorithm, the model weighting functions are updated by adding a model’s total gradient module matrix, which can effectively constrain the boundary of the recovery model in the iterative operation. We invert the 3D magnetization intensity for the three-component magnetic data in the spatial domain by spherical coordinates. The preconditional conjugate gradient algorithm is introduced to improve the efficiency of the solutions. We design two sets of synthetic examples to evaluate the inversion effects, which show that the improved method is more reliable than the smoothness constraint method. The boundary of the magnetic bodies is more precise, and the magnetization ranges are more focused. The method does not rely on the initial model and is suitable for magnetic vector data inversion. We also apply the algorithm to a set of Dabie orogen three-component magnetic data derived from a geomagnetic field model and verify the effectiveness of the inversion method. Full article

The bipartite entanglement of a quantum spin-1 Heisenberg diamond cluster in the presence of the external magnetic field is quantified through the negativity, which is calculated for spin pairs from a diagonal and a side of the diamond spin cluster taking into consideration two different coupling constants. The magnetic field may cause a few crossings of energy levels of the spin-1 Heisenberg diamond cluster, which is responsible at low enough temperatures for a stepwise dependence of the negativity on the magnetic field accompanied with a drop of the negativity at respective magnetic-field-driven transitions due to emergence of mixed states. It is shown that the bipartite entanglement between spin pairs on a diagonal and a side of the diamond spin cluster is concurrent although they may eventually become both nonzero albeit not fully saturated. It is predicted that the tetranuclear nickel complex [Ni${}_4$($\mu$-CO${}_3$)${}_2$(aetpy)${}_8$](ClO${}_4$)${}_4$ (aetpy = 2-aminoethyl-pyridine), which represents an experimental realization of the spin-1 Heisenberg diamond cluster with two different antiferromagnetic coupling constants, exhibits a substantial bipartite entanglement between two spin-1 Ni${}^{2+}$ magnetic ions from a shorter diagonal of the diamond spin cluster up to temperatures approximately about 50 K and up to magnetic fields about 70 T. Full article

Water has attracted plenty of attention as a lubricant for manufacturing due to the fact that it is inexpensive, environmentally friendly, and efficient. Because of their outstanding mechanical capabilities, water dispensability, and range of real applications, graphene oxide (GO) materials have the potential to augment the effectiveness of water lubrication. With this encouragement, we inspect the impact of induced magnetism on the fluid flow near a stagnation point dispended with water-based GO nanoparticles caused by a movable surface with a homogeneous–heterogeneous chemical reaction. The leading equations and their related boundary constraints are first transformed into a non-dimensional form through the utilization of the similarity technique. The consequent equations are then numerically solved by employing the bvp4c scheme. Those figures are used to exemplify the stimulation of the relevant constraints on the fluid flow, induced magnetic profiles, temperature profiles, concentration profiles, heat transfer, and friction factor. It is observed that the nanoparticle’s volume fraction enhances the heat transfer rate, as well as the friction factor. The heat transfer and friction factor escalate by almost 11.71% and 0.96% for the respective upper-branch solutions due to the larger impacts of nanoparticles’ volume fractions, while for the lower-branch solutions, they are augmented at about 21.8% and 0.66%, respectively. In addition, double solutions can be found in the limited values of a movable parameter. Full article

We report the dependence of the domain wall depinning field, domain wall velocity, including anisotropy direction, and magnetic properties on the oxidized aluminum thickness of perpendicularly magnetized asymmetric Pt/Co/AlO_x trilayers. We also adopt the low-temperature magneto-transport measurement technique to investigate the amount of oxygen at the Co/AlO_x interface of our magnetic thin films. At the lowest temperature of 25 K, it is found that the coercivity for the 5 nm aluminum thickness sample is very close to the average value and coercivity diminished above and below this critical aluminum thickness, hinting at a large variation in CoO_x content at the interface. This tendency is also consistent with the modification of the depinning fields, coercive fields, and surface roughness measured at room temperature. Our results highlight an efficient way of controlling the depinning fields and other magnetic characteristics, which is important for stabilizing and driving magnetic spin textures and applicable to energy-efficient next-generation spintronics devices. Full article

The series of Co(II), Fe(II), and Ni(II) mononuclear coordination compounds of [CoL(NCS)₂]·3DMSO (1), [CoL(H₂O)₂](ClO₄)₂·DMSO (2), [CoL(H₂O)(EtOH)][CoCl₄]·2H₂O (2a), [FeL(NCS)₂]·DMSO (3), and [NiL(NCS)₂]·CH₃CN (4) composition (where L is 2,6-bis(1-(2-(4,6-dimethylpyrimidin-2-yl)hydrazineylidene)ethyl)pyridine), with an [MLA₂] coordination unit (where A is a pair of apical monodentate ligands), was synthesized. In compounds 1, 2, 2a, and 3, the ligand L is pentadentate, and cobalt and iron ions are placed in a heavily distorted pentagonal pyramidal coordination environment, while in 4 the Ni(II) ion is hexacoordinated. Easy plane-type magnetic anisotropy (D = 13.69, 11.46, 19.5, and 6.2 cm⁻¹ for 1, 2, 2a, and 4, respectively) was established for cobalt and nickel compounds, while easy axis-type magnetic anisotropy (D = −14.5 cm⁻¹) was established for iron compound 3. The cobalt coordination compounds 1 and 2 show SIM behavior under a 1500 Oe external magnetic field, with effective magnetization reversal barriers of 65(1) and 60(1) K for 1 and 2, respectively. The combination of Orbach and Raman relaxation mechanisms was shown to adequately describe the temperature dependence of relaxation times for 1 and 2. CASSCF/NEVPT2 calculations were performed to model the parameters of the effective spin Hamiltonian for the compounds under study. Full article

The metal–insulator transition in the organic quasi-two-dimensional metal κ-(BEDT-TTF)₂Hg(SCN)₂Br at T_MI ≈ 90 K has been investigated. The crystal structure changes during this transition from monoclinic above T_MI to triclinic below T_MI. A theoretical study suggested that this phase transition should be of the metal-to-metal type and brings about a substantial change of the Fermi surface. Apparently, the electronic system in the triclinic phase is unstable toward a Mott insulating state, leading to the growth of the resistance when the temperature drops below T_MI ≈ 90 K. The application of external pressure suppresses the Mott transition and restores the metallic electronic structure of the triclinic phase. The observed quantum oscillations of the magnetoresistance are in good agreement with the calculated Fermi surface for the triclinic phase, providing a plausible explanation for the puzzling behavior of κ-(BEDT-TTF)₂Hg(SCN)₂Br as a function of temperature and pressure around 100 K. The present study points out interesting differences in the structural and physical behaviors of the two room temperature isostructural salts of κ-(BEDT-TTF)₂Hg(SCN)₂X with X = Br, Cl. Full article

Herein, we report the synthesis, structure and magnetic properties of two mononuclear complexes of general formula [Dy(acac)₃(L)], where L = 2,2-dimethyl-1,3-dioxolo[4,5-f][1,10] phenanthroline (1) or 1,10-phenanthroline-5,6-dione (2), and acac⁻ = acetylacetonate anion. A distorted square-antiprismatic N₂O₆ environment around the central Dy(III) ion is formed by three acetylacetonate anions and a phenanthroline-type ligand. Both complexes display a single-molecule magnet (SMM) behavior at zero applied magnetic field. Modification of the peripheral part of ligands L provide substantial effects both on the magnetic relaxation barrier U_eff and on the quantum tunneling of magnetization (QTM). Ab initio quantum-chemical calculations are used to analyze the electronic structure and magnetic properties. Full article

In recent years, researchers have been making a persistent effort to discover innovative and appropriate oxide materials that can be exploited in optoelectronics devices. The primary objective of this research is to study the effect of Na/Mg co-doping on microstructure, transport (dielectric and Hall Effect), optical and magnetic properties of Ti_0.94-yNa_0.06Mg_yO₂ (y = 0–0.08) compounds that were synthesized using a solid-state route method. All the compounds have been crystallized to a single rutile phase, as reported by the XRD study. The elemental color mapping reveals that there is a consistent distribution of all of the elements across the compound. The XPS study suggests that Ti mostly resided in the Ti⁴⁺ oxidation state. The enhancement of the Mg co-doping concentration led to a decrease in the dielectric value as well as the AC conductivity of the material. In addition to this, it has been noted that these compounds have a low dielectric loss. The analyses of Nyquist plots reveal that the increase of Mg co-doping concentration led to a rise in the amount of relaxation that is non-Debye sort. This, in turn, caused a reduction in the amount of resistance exhibited by grains and grain boundaries. The Maxwell–Wagner model was used to conduct an analysis of the dielectric data, and the results indicated that the hopping of charge carriers is most likely to be responsible for the transport of electrical charges. From the optical properties’ measurement and analyses, it was noticed that the band gap had been slightly changed, but the transmittance value had increased from 81% for Ti_0.94Na_0.06O₂ to 84% with an increase in Mg co-doping concentration. The Hall Effect analysis unequivocally pointed to the presence of p-type conductivity as well as an increased carrier density concentration. The room temperature magnetization versus field measurement indicates the ferromagnetic nature of the samples. Thus, the co-doping of Mg with Na in TiO₂ leads to a narrowing of the band gap of TiO₂ while tweaking the optical and transport properties. The studied materials can be utilized for spintronics and optoelectronics applications. Full article

Sm₂Fe₁₇N₃ compounds, having excellent intrinsic magnetic properties, are prone to decomposition at high temperatures; thus, a low melting point metal binder is the key to prepare high performance bulk magnets at low temperatures. In this paper, a new low melting point alloy Ce₇₂Cu_28-xAl_x was used as the binders, and high-performance Ce-based alloy bonding Sm₂Fe₁₇N₃ magnets were realized by the hot-pressing method. The experimental results demonstrated that the content of Al in the Ce-based alloys had an important influence on the performance of the magnets. High performance Sm-Fe-N bonded magnets with remanence of 10.19 KGs and maximum magnetic energy product of 21.06 MGOe were achieved by using 5 wt.% Ce₇₂Cu₂₂Al₆ alloy as a binder. At the same time, it was found that the Ce₇₂Cu_28-xAl_x alloy has a lower density and better bonding effect than the common Zn binder. Its bonding magnets still have higher performance even with extremely high oxygen content. Therefore, Ce₇₂Cu_28-xAl_x alloy with low melting point is a promising new rare earth-based alloy binder. If the oxygen content of the alloy powders could be reduced, higher performance Sm₂Fe₁₇N₃ bonded magnets can be prepared. Full article

Alternating TiB₂-dcMS and Cr-HiPIMS layers are used to fabricate TiB₂/Cr multilayer films. Introducing a 5-nm-thick Cr interlayer deposited under a substrate bias of −60 V produces slight increases in both film hardness and elastic modulus. The TEM observation indicates that the Cr grains favor epitaxial growth on the TiB₂ interlayer, forming a coherent TiB₂/Cr interface. This improves hardness. Mechanic measurement by using AFM illustrates that the coherent interface increases the elastic modulus of the Cr up to ~280 GPa, which is significantly higher than bulk material. Full article

Electroporation is a technique applied both in biomedical and biotechnological fields which uses a high-voltage electric current to temporarily destabilize the plasma membrane of living cells, permitting the introduction of small molecules as well as nucleic acids into the cytosol. Besides viral and chemical transfections, this method is a common way to manipulate living cells. However, the majority of electroporation machines available on the market can only work using batch-based cuvettes treating only a few micrograms of cells. To transform cells in the order of several grams in the quickest possible way, it is necessary to use a continuous-flow method. In this work, we present the design, electric and fluid dynamics simulations, construction and testing of a flow cuvette that can adapt to standard electroporator systems. The flow cuvette connected with a peristaltic pump was able to successfully electroporate 20 mL of medium containing microalgae cells in less than 5 min. Microalgae Scenedesmus almeriensis cells were transfected with a fluorescent siRNA oligo as well as magnetically transformed by introducing magnetic nanoparticles in their cytoplasm. The flow cuvette presented here offers a valid tool for the high-throughput transformation/transfection/transfer of both prokaryotic and eukaryotic organisms, especially suitable for bioreactor cultivation and other industrial biotechnological contexts. Full article

In our research, the magnetic field-induced deformation of isotropic magnetorheological elastomer (MRE) discs loaded with two types of magnetite and an iron powder were examined. A measurement system using a microscope camera was assembled, and the magnitude of the deformation was determined from the optical contour obtained with digital image processing. We found that the MRE discs with a height-to-width aspect ratio of 1:2 underwent expansion in the direction of the external field in all cases. The magnitude of the dilatation increased with the magnetic field strength in cases of all filler materials, but the exact trend depended on the type and concentration of the filler. An inhibition of the polymerization of the matrix was observed in the case of one of the magnetite fillers, which resulted in a decreased zero-field elastic modulus at higher particle loadings. A correlation was found between the reduced elastic modulus and the increased magnitude of the deformation. Full article

Magnetic iron oxide nanoparticles were obtained for the first time via the green chemistry approach, starting from two aqueous extracts of wormwood (Artemisia absinthium L.), both leaf and stems. In order to obtain magnetic nanoparticles suitable for medical purposes, more precisely with hyperthermia inducing features, a synthesis reaction was conducted, both at room temperature (25 °C) and at 80 °C, and with two formulations of the precipitation agent. Both the quality and stability of the synthesized magnetic iron oxide nanoparticles were physiochemically characterized: phase composition (X-ray powder diffraction (XRD)), thermal behavior (thermogravimetry (TG) and differential scanning calorimetry (DSC)), electron microscopy (scanning (SEM) and transmission (TEM)), and magnetic properties (DC and HF-AC). The magnetic investigation of the as-obtained magnetic iron oxide nanoparticles revealed that the synthesis at 80 °C using a mixture of NaOH and NH₃(aq) increases their diameter and implicitly enhances their specific absorption rate (SAR), a mandatory parameter for practical applications in hyperthermia. Full article

We use density functional theory (DFT) calculations to show that oxygen vacancies ($v_{\mathrm{O}}$) and mobility induce noncentrosymmetric polar structures in SrTi${}_{1-x-y}$Fe${}_x$Co${}_y$O${}_{3-\delta }$ (STFC, $x=y=0.125$) with $\delta =\{0.125,0.25\}$, enhance the saturation magnetization, and give rise to large changes in the electric polarization $|\Delta P|$. We present an intuitive set of rules to describe the properties of STFC, which are based on the interplay between (Co/Fe)-$v_{\mathrm{O}}$ defects, magnetic cation coordination, and topological vacancy disorder. STFC structures consist of layered crystals with sheets of linearly organized O${}_{4,5,6}$-coordinated Fe–Co pairs, sandwiched with layers of O${}_5$-coordinated Ti. (Co/Fe)-$v_{\mathrm{O}}$ defects are the source of crystal distortions, cation off-centering and bending of the oxygen octahedra which, considering the charge redistribution mediated by $v_{\mathrm{O}}$ and the cations’ electronegativity and valence states, triggers an effective electric polarization. Oxygen migration for $\delta =0.125$ leads to $|\Delta \mathbf{P}|$>∼10 µC/cm${}^2$ due to quantum-of-polarization differences between $\delta =0.125$ structures. Increasing the oxygen deficiency to $\delta =0.25$ yields $|\Delta \mathbf{P}|$, the O migration of which resolved polarization for $\delta =0.25$ is $>\sim$3 µC/cm${}^2$. Magnetism is dominated by the Fe,Co spin states for $\delta =0.125$, and there is a contribution from Ti magnetic moments (∼1 ${\mu }_B$) for $\delta =0.25$. Magnetic and electric order parameters change for variations of $\delta$ or oxygen migration for a given oxygen deficiency. Our results capture characteristics observed in the end members of the series SrTi(Co,Fe)O${}_3$, and suggest the existence of a broader set of rules for oxygen-deficient multiferroic oxides. Full article

In this study, three types of hydrophobized alkyl-modified magnetic nanoparticles (MNPs) comprising direct alkylated-MNPs (A-MNPs), silica-mediated alkyl MNPs (A-SiMNPs), and arginine (Arg)-mediated alkyl MNPs (A-RMNPs) were synthesized successfully. For this purpose, the co-precipitation method was used to synthesize, and octadecyl trimethoxy silane (OTMS) was used as a functionalizing agent. Accordingly, the hydrophobic octadecyl moieties were connected to MNPs. The nanoparticles (NPs) were characterized by XRD, SEM, FTIR, CHN, DLS, and zeta potential analyses. The synthesized coated MNPs represented a decrease in surface charge and magnetization alongside increased surface hydrophobicity and size. It was revealed that the alkylation process was successfully performed to all three MNPs, but A-SiMNPs showed the highest hydrophobicity. Additionally, the novel A-RMNPs, as the most biocompatible type, and A-MNPs showed the highest magnetization among the synthesized MNPs. The results indicate that synthesized NPs can play an important role in bio applications. However, it was revealed that alkyl chains are easily connected to all three MNPs, and that A-MNPs contained the highest alkyl chains and could affect the re-folding and denaturation process of recombinant proteins. Full article

Molecular semiconductors with lanthanide ions have been synthesized based on BEDT-TTF and lanthanide chlorides: (BEDT-TTF)₂[HoCl₂(H₂O)₆]Cl₂(H₂O)₂ (1, which contains a 4f holmium cation), and (BEDT-TTF)₂LnCl₄(H₂O)_n (Ln = Dy, Tb, Ho (2–4), which contain 4f anions of lanthanides). Conductivity and EPR measurements have been carried out along with the SQUID magnetometry, and the crystal structure has been established for 1. The structure of 1 is characterized by an alternation of organic radical cation layers composed of BEDT-TTF chains and inorganic layers consisting of chains of the [HoCl₂(H₂O)₆]⁺ cations interlinked by chlorine anions and crystallization water molecules. The magnetic susceptibility of 1–3 determined mainly by lanthanide ions follows the Curie–Weiss law with the Weiss temperatures of −3, −3, −2 K for 1–3, respectively, indicating weak antiferromagnetic coupling between paramagnetic lanthanide ions. The signals attributed to the BEDT-TTF^+· radical cations only are observed in the EPR spectra of 1–3, which makes it possible to study their magnetic behavior. There are two types of chains in the organic layers of 1: the chains composed of neutral molecules and those formed by BEDT-TTF^+· radical cations. As a result, uniform 1D antiferromagnetic coupling of spins is observed in the BEDT-TTF^+· chains with estimated exchange interaction J = −10 K. The study of dynamic magnetic properties of 1–3 shows that these compounds are not SMMs. Full article

A novel technique to enhance the bandwidth of mobile phone antennas using YIG ferrite is proposed. The technique is applied in two slot antennas which are the proposed antenna and the reference antenna. The two antennas have the same shaped slot consisting of a rectangle connected to a circle etched on the ground plane. A ferrite slab is attached at the region near the circular slot on the ground plane of each antenna. The measured bandwidth of the proposed antenna with ferrite slab is enhanced to 0.669–1.533 and 1.69–5 GHz compared with the bandwidth of 0.81–1.44 and 2.3–5 GHz for the antenna without ferrite. The bandwidth of the reference antenna with ferrite slab is enhanced to 0.715–5 GHz compared with the bandwidth of 0.813–1.01, 1.11–1.3 and 2.33–5 GHz for the antenna without ferrite loading. The technique has the virtues of easy fabrication and low cost. Full article

Magnetic fields affect electrolytes in diverse ways. This paper focuses on the interactions among electric, magnetic, and flow fields and the applications of the resulting phenomena in microfluidics. When an electrical current is transmitted in an electrolyte in the presence of an external magnetic field, a Lorentz body force results, which may induce pressure gradients and fluid motion—magnetohydrodynamics (MHD). The resulting advection is used to pump fluids, induce/suppress flow instabilities, and control mass transfer in diverse electrochemical processes. When an electrolyte flows in the presence of a magnetic field, electromotive force (emf) is induced in the electrolyte and can be used for flow metering, hydrogen production, and energy conversion. This review describes the governing equations for modeling MHD flows in electrolytes and MHD phenomena and applications relevant to microfluidic systems, such as the use of MHD to pump and stir fluids, propel swimmers, and control fluid flow in fluidic networks without any mechanical components. The paper also briefly assesses the impact of magnetic resonance imaging (MRI) on blood flow. MHD in electrolytes is a highly interdisciplinary, combining electrokinetics, fluid mechanics, electrochemistry, and Maxwell equations. Full article

The use of a variety of microorganisms for the degradation of chemicals is a green solution to the problem of environmental pollution. In this work, fungi–magnetic nanoparticles were studied as systems with the potential to be applied in environmental remediation and pest control in agriculture. High food demand puts significant pressure on increasing the use of herbicides, insecticides, fungicides, pesticides, and fertilizers. The global problem of water pollution also demands new remediation solutions. As a sustainable alternative to commercial chemical products, nanobiocomposites were obtained from the interaction between the fungus M. anisopliae and two different types of magnetic nanoparticles. Fourier transform infrared spectroscopy, optical and electron microscopy, and energy dispersive spectroscopy were used to study the interaction between the fungus and nanoparticles, and the morphology of individual components and the final nanobiocomposites. Analyses show that the nanobiocomposites kept the same morphology as that of the fungus in natura. Magnetic measurements attest the magnetic properties of the nanobiocomposites. In summary, these nanobiocomposites possess both fungal and nanoparticle properties, i.e., nanobiocomposites were obtained with magnetic properties that provide a low-cost approach benefiting the environment (nanobiocomposites are retrievable) with more efficiency than that of the application of the fungus in natura. Full article

Gd flake samples were prepared by conventional ball milling technique starting from rapidly quenched Gd ribbons and followed by vacuum annealing in different conditions. Heat treatments were conducted in a vacuum at selected temperatures up to 600 K. The structural features, magnetic and magnetocaloric properties were comparatively analyzed. The change in magnetic entropy was calculated using an experimental set of magnetic isotherms measured in a wide range of temperatures. The variations in the refrigeration capacity and the exponent of the magnetic entropy change in the external magnetic field were carefully calculated and analyzed. Full article

In this work, a hematite/porous graphite carbon-nitride (α-Fe₂O₃/g-C₃N₄) catalyst was synthesized through the doping of hematite loaded onto porous graphite carbon-nitride using a heat treatment process. Then, the ability of catalyst was evaluated to degrade diazinon (DZN) for the first time, mainly via the sonophotocatalytic process. Among the samples, the greatest DZN degradation was observed in the sonophotocatalytic system, which separated 100% of DZN from the aqueous solution after 50 min, while the removal percentages for the sonocatalytic, photocatalytic, and adsorption systems were 72.9, 89.1, and 58.1%, respectively. The results of scavengers showed that both sulfate and hydroxyl radicals (^•OH) participated in removing DZN, although positive holes and negative ^•OH played a major role. Moreover, the removal efficiencies of the target pollutant using the sonophotocatalytic process were higher than those using the photocatalytic, sonocatalytic, and adsorption processes. The reaction profile followed pseudo-first-order kinetics, and the reaction rate coefficient for the sonophotocatalytic system was 2.2 times higher than that of the photocatalytic system and 2.64 times higher than that of the sonocatalytic system. The energy consumption of the sonophotocatalytic system after 60 min was 11.6 kWh/m³, while it was 31.1 kWh/m³ for the photocatalytic system. A DZN removal percentage of 100% was obtained after 50 min under the following conditions: UV intensity of 36 watts, ultrasound frequency of 36 kHz, DZN concentration of 50 mg/L at pH 5, and α-Fe₂O₃/g-C₃N₄ dosage of 0.4 g/L. The catalyst reusability was examined with only a 9.9% reduction in efficiency after eight consecutive cycles. The chemical oxygen demand (COD) and total organic compound (TOC) removal percentages were 95.6% and 88.6%, respectively, and the five-day biochemical oxygen demand (BOD₅)/COD ratio was 0.16 at the beginning of the degradation process and 0.69 at the end of the process. In addition, toxicological experiments showed that degradation of DZN by the sonophotocatalytic process exhibited low toxicity. All results confirmed that the sonophotocatalytic process using α-Fe₂O₃/g-C₃N₄ was a highly efficient process for DZN pollutant removal from liquid wastes. Full article