Magnetic anisotropy determination and magnetic hyperthermia properties of small Fe nanoparticles in the superparamagnetic regime

We report on the magnetic and hyperthermia properties of iron nanoparticles synthesized by organometallic chemistry. They are 5.5 nm in diameter and display a saturation magnetization close to the bulk one. Magnetic properties are dominated by the contribution of aggregates of nanoparticles with respect to individual isolated nanoparticles. Alternative susceptibility measurements are been performed on a low interacting system obtained after eliminating the aggregates by centrifugation. A quantitative analysis using the Gittleman s model allow a determination of the effective anisotropy Keff = 1.3 * 10^5 J.m^{-3}, more than two times the magnetocristalline value of bulk iron. Hyperthermia measurements are performed on agglomerates of nanoparticles at a magnetic field up to 66 mT and at frequencies in the range 5-300 kHz. Maximum measured SAR is 280 W/g at 300 kHz and 66 mT. Specific absorption rate (SAR) displays a square dependence with the magnetic field below 30 mT but deviates from this power law at higher value. SAR is linear with the applied frequency for mu_0H=19 mT. The deviations from the linear response theory are discussed. A refined estimation of the optimal size of iron nanoparticles for hyperthermia applications is provided using the determined effective anisotropy value

Identifying effluents from a food processing industry

The agri-food industry in Morocco generates significant volumes of liquid waste, contributing to environmental challenges that directly impact public health. To address this issue, it is crucial to characterize this wastewater comprehensively, enabling the development of suitable treatment strategies to alleviate pollution and potentially facilitate recycling. This study focuses on the identification of effluents from an olive and caper preservation industry, employing physicochemical and bacteriological analyses on raw, decanted, and filtered effluent samples. The findings reveal that the effluent from the olive and caper preservation industry is characterized by high acidity and an exceptionally elevated mineral load. Notably, the application of decantation and filtration methods demonstrates a limited influence, primarily affecting the reduction of suspended solids. Understanding these physicochemical and bacteriological characteristics is pivotal for devising targeted treatment protocols, ensuring effective pollution reduction, and exploring avenues for potential recycling of this agri-food industry wastewater. This research serves as a foundation for informed decision-making in the development of sustainable and efficient wastewater management practices, balancing environmental preservation with industrial needs

Large specific absorption rates in the magnetic hyperthermia properties of metallic iron nanocubes

We report on the magnetic hyperthermia properties of chemically synthesized ferromagnetic 11 and 16 nm Fe(0) nanoparticles of cubic shape displaying the saturation magnetization of bulk iron. The specific absorption rate measured on 16 nm nanocubes is 1690+-160 W/g at 300 kHz and 66 mT. This corresponds to specific losses-per-cycle of 5.6 mJ/g, largely exceeding the ones reported in other systems. A way to quantify the degree of optimization of any system with respect to hyperthermia applications is proposed. Applied here, this method shows that our nanoparticles are not fully optimized, probably due to the strong influence of magnetic interactions on their magnetic response. Once protected from oxidation and further optimized, such nano-objects could constitute efficient magnetic cores for biomedical applications requiring very large heating power

What effects does an organic amendment to olive waste have on the soil and crop yield?

Intensive agriculture or phenomena such as pollution, compaction, and/or erosion lead to a decrease in the amounts of organic matter of soils; thus, causing a decrease in their fertility. The use of an organic amendment in agriculture could combat soil degradation. In this sense, two organic amendments with olives waste (OW) and olive mill wastewater (OMW) have been manufactured.  The objective of this work is to examine the capacity of these amendments to improve soil quality in comparison with manure (M). Three types of soil were tested: the first has been amended for two years with a compost of similar composition (S1), the second not amended (S2), and the third corresponds to an agricultural soil that is amended with chemical fertilizer (S3). All the trials were carried out on two vegetable gardens: potato and radish. The ANOVA shows that the amendment effect was highly significant on all the physicochemical parameters studied except humidity. In conclusion, this product could be an alternative to chemical fertilizers and considered as a perennial solution adapted to the context of sustainable development to the recovery of olive waste

Study of Cu/In/Se/Se thin films prepared by the Stacked Elemental Layer (SEL) technique

CuInSe2 thin films have been grown on Corning glass and Si (100) substrates using stacked elemental layers (SEL) processing. The influence of substrate’s nature and substrate’s temperature were studied. X-ray diffraction and SEM measurements have shown that the films exhibit an excellent crystallinity and crystallize in a tetragonal structure. Scanning electron microscopy investigations have shown that the films consist in a structure with large grains in the range 80 – 200 nm. Increasing the deposition temperature from room temperature to 300 °C has lead to a change in the composition and morphology of the films. Characteristic peaks of the chalcopyrite structure such as (101), (211) and (311) were clearly observed for both layers upon annealing at 450°C as evidenced by X-ray diffraction study. The determined lattice parameters were a = 0.57725 (6) nm, b = 1.1621 (2) nm for sample prepared at room temperature and a = 0.57770 (4) nm, b = 1.1602 (1) nm for Ts = 300°C. The crystallographic structure of the CuInSe2 sample was analyzed by Rietveld analysis using X-ray powder diffraction data. UV-Vis-NIR Spectrophotometry was used to investigate the optical characteristics of different Cu/In/Se/Se thin layers in the spectral range between 300 – 2000 nm. The optical band-gap of our materials increases from 0.98 to 1.01 eV

Agronomic valorization of the composts with olive waste

In the Mediterranean countries, olive waste, a co-product of the olive oil trituration process, presents a serious environmental problem because of their polyphenol charge, given the quantities rejected each year. In previous works, this waste has been co-composted with other substrates and has been transformed into non-phytotoxic substances in conformity with the French standard NFU44-051 due to their composition in nutritional elements like soluble sugars, proteins and mineral elements. This study examines the efficacy of these substances on radish and potato crops. To do this, seeds were sown on the plot. For each crop, 4 plots were planned: land amended with manure (M), NPK fertilizer (F), the vegetable water substance (VW) and the olive-pomace substance (OP) in addition to the vegetable water. The first three substances served as controls. A statistical study of correlation between the latter and those that characterize the soil after amendment was carried out.  The obtained results showed that there are two strong correlations between pH, organic matter, dry matter and soil moisture amended by the OW compost and, on the one hand, the morphological growth parameters of the two crops and, on the other hand, the parameters of their production

Particle interactions in liquid magnetic colloids by zero field cooled measurements: effects on heating efficiency

The influence of magnetic interactions in assemblies formed by either aggregated or disaggregated uniform gamma-Fe_2O_3 particles are investigated as a function of particle size, concentration, and applied field. Hyperthermia and magnetization measurements are performed in the liquid phase of colloids consisting of 8 and 13 nm uniform gamma-Fe_2O_3 particles dispersed in water and hexane. Although hexane allows the disagglomerated obtaining particle system; aggregation is observed in the case of water colloids. The zero field cooled (ZFC) curves show a discontinuity in the magnetization values associated with the melting points of water and hexane. Additionally, for 13 nm gamma-Fe_2O_3 dispersed in hexane, a second magnetization jump is observed that depends on particle concentration and shifts toward lower temperature by increasing applied field. This second jump is related to the strength of the magnetic interactions as it is only present in disagglomerated particle systems with the largest size, i.e., is not observed for 8 nm superparamagnetic particles, and surface effects can be discarded. The specific absorption rate (SAR) decreases with increasing concentration only for the hexane colloid, whereas for aqueous colloids, the SAR is almost independent of particle concentration. Our results suggest that, as a consequence of the magnetic interactions, the dipolar field acting on large particles increases with concentration, leading to a decrease of the SAR