Concentration Of Fe3O4 Nanoparticles Research Articles

Evidence of Cooperative Effects for the Fe(phen)2(NCS)2 Spin Crossover Molecular Complex in Polyaniline Plus Iron Magnetite.

The spin crossover complex Fe(phen)2(NCS)2 and its composite, Fe(phen)2(NCS)2, combined with the conducting polymer polyaniline (PANI) plus varying concentrations of iron magnetite (Fe3O4) nanoparticles were studied. A cooperative effect is evident from the hysteresis width in the plot of magnetic susceptibility multiplied by temperature versus temperature (χmT versus T) for Fe(phen)2(NCS)2 with PANI plus varying concentrations of Fe3O4 nanoparticles. The hysteresis width in the composites vary no more than 2 K with respect to the pristine Fe(phen)2(NCS)2 spin crossover crystallites despite the fact that there exists a high degree of miscibility of the Fe(phen)2(NCS)2 spin crossover complex with the PANI. The Fe3O4 nanoparticles in the Fe(phen)2(NCS)2 plus PANI composite tend to agglomerate at higher concentrations regardless of the spin state of Fe(phen)2(NCS)2. Of note is that the Fe3O4 nanoparticles are shown to be antiferromagnetically coupled with the Fe(phen)2(NCS)2 when Fe(phen)2(NCS)2 is in the high spin state.

Nanocomposites of Poly(n-Butyl Acrylate) with Fe3O4: Crosslinking with Hindered Urea Bonds, Reprocessing and Related Functional Properties.

In this contribution, we reported the synthesis of the nanocomposites of poly(n-butyl acrylate) with Fe3O4 nanoparticles (NPs) via dynamic crosslinking of poly(n-butyl acrylate)-grafted Fe3O4 NPs with hindered urea bonds (HUBs). Towards this end, the surfaces of Fe3O4 NPs were grafted with poly(n-butyl acrylate-ran-2-(3-tert-butyl-3-ethylureido)ethyl acrylate) chains [denoted as Fe3O4-g-P(BA-r-TBEA)] via living radical polymerization. Thereafter, 1,2-bis(tert-butyl)ethylenediamine was used as a crosslinker to afford the organic-inorganic networks with variable contents of Fe3O4 NPs and crosslinking densities. It was found that the fine dispersion of Fe3O4 NPs in the matrix of poly(n-butyl acrylate) was achieved. The nanocomposites exhibited excellent reprocessing properties, attributed to the introduction of HUBs. Owing to the crosslinking, the nanocomposites displayed excellent shape memory properties. Further, the nanocomposites possessed photo- and magnetic-thermal properties, which were inherited from Fe3O4 NPs. These functional properties allow triggering the shape shifting of the nanocomposites in an uncontacted fashion.

One-Step Preparation Method and Rapid Detection Implementation Scheme for Simple Magnetic Tagging Materials

With the widespread application of tagging materials, existing chemical tagging materials exhibit limitations in stability and detection under field conditions. This study introduces a novel magnetic detection scheme. Hydrophilic material-modified Fe3O4 nanoparticles (COOH-PEG@Fe3O4 NPs) were synthesized using the co-precipitation technique. The content of Fe3O4 nanoparticles in the magnetic tagging liquid can reach up to 10 wt% and remain stable in an aqueous phase system for seven days. This research details the preparation process, the characterization methods (IR, 1HNMR, EDX, XRD, SEM, TEM, VSM, DLS), and the performance effects of the materials in magnetic tagging. Experimental results indicate that COOH-PEG@Fe3O4 NPs exhibit high remanence intensity (Br = 1.75 emu/g) and considerable stability, making it possible to quickly detect tagged liquids in the field using portable flux meters and optical pump magnetometers. This study provides new insights into the design and application of magnetic tagging materials, making it particularly suitable for long-term tagging and convenient detection in field scenarios.

Controlling the Magnetic Responsiveness of Cellulose Nanofiber Particles Embedded with Iron Oxide Nanoparticles.

2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofiber (TOCN) particles, an innovative biobased material derived from wood biomass, have garnered significant interest, particularly in the biomedical field, for their distinctive properties as biocompatible particle adsorbents. However, their microscopic size complicates their separation in liquid media, thereby impeding their application in various domains. In this study, superparamagnetic magnetite nanoparticles (NPs), specifically iron oxide Fe3O4 NPs with an average size of 15 nm, were used to enhance the collection efficiency of TOCN-Fe3O4 composite particles synthesized through spray drying. These composite particles exhibited a remarkable ζ-potential (approximately -50 mV), indicating their high stability in water, as well as impressive magnetization properties (up to 47 emu/g), and rapid magnetic responsiveness within 60 s in water (3 wt % Fe3O4 to TOCN, 1 T magnet). Furthermore, the influence of Fe3O4 NP concentrations on the measurement of the speed of magnetic separation was quantitatively discussed. Additionally, the binding affinity of the synthesized particles for proteins was assessed on a streptavidin-biotin binding system, offering crucial insights into their binding capabilities with specific proteins and underscoring their significant potential as functionalized biomedical materials.

Stabilized superhydrophobic composite membranes prepared by electrospinning for oil–water separation

AbstractIn dealing with the oil–water separation process, improving the oil–water selectivity of the membrane surface and increasing the porosity within the membrane are effective means to achieve durable and efficient oil–water separation. Therefore, polystyrene/polyacrylonitrile‐polyvinylidene fluoride/Polydimethylsiloxane Fe3O4 nanoparticles (PS/PAN‐PVDF/PDMS@Fe3O4) composite membranes with superhydrophobicity and lipophilicity were prepared by electrospinning technique. By controlling the filling concentration of Fe3O4 nanoparticles, a stable superhydrophobic and lipophilic rough structure was constructed, and micro–nano multilayer rough voids existed inside the membrane. The results showed that the composite fiber membrane exhibited exceptional superhydrophobicity (156.2°), thermal stability (338°C), mechanical properties (tensile strength of 3.0 MPa, elongation of 33.9%), and oil adsorption capacity (30–100 g/g). Moreover, even under corrosive environments, this composite fiber membrane maintained its superhydrophobic properties (above 152°) and achieved high oil–water separation efficiency (above 97%). Remarkably, after 40 cycles, the composite membrane could sustain a separation flux of 5000 L m−2 h−1. Consequently, the composite fiber membrane manufactured using this strategy exhibits promising potential for applications in oil–water separation.

Computer simulation-based nanothermal field and tissue damage analysis for cardiac tumor ablation.

Radiofrequency ablation is a nominally invasive technique to eradicate cancerous or non-cancerous cells by heating. However, it is still hampered to acquire a successful cell destruction process due to inappropriate RF intensities that will not entirely obliterate tumorous tissues, causing in treatment failure. In this study, we are acquainted with a nanoassisted RF ablation procedure of cardiac tumor to provide better outcomes for long-term survival rate without any recurrences. A three-dimensional thermo-electric energy model is employed to investigate nanothermal field and ablation efficiency into the left atrium tumor. The cell death model is adopted to quantify the degree of tissue injury while injecting the Fe3O4 nanoparticles concentrations up to 20% into the target tissue. The results reveal that when nanothermal field extents as a function of tissue depth (10mm) from the electrode tip, the increasing thermal rates were approximately 0.54362%, 3.17039%, and 7.27397% for the particle concentration levels of 7%, 10%, and 15% compared with no-particle case. In the 7% Fe3O4 nanoparticles, 100% fractional damage index is achieved after ablation time of 18s whereas tissue annihilation approach proceeds longer to complete for no-particle case. The outcomes indicate that injecting nanoparticles may lessen ablation time in surgeries and prevent damage to adjacent healthy tissue.

Assessing the effect of Fe2O3 nanoparticle addition on microalgae wastewater treatment and biomass composition

The addition of Fe2O3 nanoparticles to microalgae cultures has gained popularity since it has been demonstrated to enhance microalgae growth and metabolite accumulation. However, most of the literature has been focused on small batch laboratory-scale studies under controlled conditions and the need of continuous studies under real environmental conditions is needed to demonstrate the feasibility of this process. In this study, the effect of Fe2O3 nanoparticles on the metabolism and nutrient uptake of a microalgae-cyanobacteria consortium cultivated in wastewater was elucidated. Different concentrations of Fe2O3 nanoparticles (10, 20, 30 and 70 mg L−1) were assessed at least for 21 days in outdoor cylindrical PBRs at 7 days of hydraulic retention time. No significant difference in microalgae growth, microalgae biomass composition and nutrient uptake was observed at concentrations <30 mg L−1. Moreover, when 30 mg L−1 were added to the culture, the carbohydrate content increased up to 38 % but a decrement in biomass concentration of 18 % was observed by the deposition of nanoparticles on the cyanobacteria cell wall. The addition of 70 mg Fe2O3 L−1 reduced the content of carbohydrate and biomass concentration but did not influence the nutrient uptake from wastewater. In brief, Fe2O3 NP supplementation at 30 mg L−1 can be added as a strategy to stimulate carbohydrate content during microalgae-based wastewater treatment.

Alginate/GelMA microparticles via oil-free interface shearing for untethered magnetic microbots.

Microrobots hold broad application prospects in the field of precision medicine, such as intravenous drug injection, tumor resection, opening blood vessels and imaging during abdominal surgery. However, the rapid and controllable preparation of biocompatible hydrogel microparticles still poses challenges. This study proposes the one-step direct acquisition of biocompatible sodium alginate and gelatin methacrylate (GelMA) hydrogel microparticles using an oil-free aqueous solution, ensuring production with a controllable generation frequency. An adaptive interface shearing platform is established to fabricate alginate/GelMA microparticles using a mixture of the hydrogel, photoinitiator, and Fe3O4 nanoparticles (NPs). By adjusting the static magnetic field intensity (Bs), vibration frequency, and flow rate (Q) of the dispersed phase, the size and morphology of the hydrogel microparticles can be controlled. These hydrogel microparticle robots exhibit magnetic responsiveness, demonstrating precise rotating and rolling movements under the influence of an externally rotating magnetic field (RMF). Moreover, hydrogel microparticle robots with a specific critical frequency (Cf) can be customized by adjusting the Bs and the concentration of Fe3O4 NPs. The directional in situ untethered motion of the hydrogel microparticle robots can be successfully realized and accurately controlled in the climbing over obstacles and in vitro experiments of animals, respectively. This versatile and fully biodegradable microrobot has the potential to precisely control movement to bone tissue and the natural cavity of the human body, as well as drug delivery.

Влияние наночастиц оксида железа Fе3O4 на структуру и теплофизические свойства нанокомпозитов на основе полиэтилена высокой плотности

HDPE/Fe3O4 composites with Fe3O4 nanofiller content ω = 1, 3 and 5 vol. %. The structure and thermophysical properties of HDPE/Fe3O4 nanocomposites were studied and it was found that with an increase in the concentration of Fe3O4 nanoparticles in the polymer matrix, cardinal morphological changes occur in the supramolecular structure of the HDPE matrix. It has been established that with an increase in the concentration of the nanofiller, the mobility of the macromolecular chains of the matrix and the thickness of the crystalline lamellae decrease. Nanoparticles disrupt the regularity of lamellae in the crystalline phase of the polymer matrix, and in the amorphous region they prevent the formation and growth of new crystalline domains.

MiR159c Expression Under Nanoparticle Stress in Flax (Linum usitatissimum L.) Calli

Abstract The rapid development of nanotechnologies has raised great interest in the use of engineered nanoparticles (NPs) and their release in the environment. The interaction between nanoparticles and crops is currently a topical problem, as nanoparticles are capable to enter the soil, plant cells and to translocate in plants. MicroRNA (miRNA) is an endogenous small RNA with a significant regulatory role in plants, cleaving or repressing the translation of a particular mRNA in response to multiple biotic and abiotic factors. In this work, the expression of miR159c in Linum usitatissimum L. calli cultures caused by various concentrations of Fe3O4 nanoparticles was studied. The obtained results showed an increase in miR159c expression with a decrease in the concentration of Fe3O4 nanoparticles. The results obtained are important in explaining the potential of nanoparticle utilisation to provide plant immunity responses.

Broad-wave reflection of polymer-stabilised cholesterol liquid crystal with nanofibers doped magnetic nanoparticles

ABSTRACT In this study, the polymer-stabilised cholesterol-based liquid crystal (PSCLC) films with broad-wave reflection were prepared via PVA nanofibers as carriers loaded with Fe3O4 nanoparticles. Fe3O4 nanoparticles have absorption properties in the UV region. When UV light is irradiated along the thickness of the liquid crystal cell, the resulting gradient distribution of UV light intensity induces a gradient distribution of spacing and thus a broad-wave reflection. Specifically, the effects of nanoparticles content loaded in nanofibers, magnetic field strength, polymerisation time and temperature, UV light intensity and polymerised monomer content were studied. The result shows that the proper contents of Fe3O4 nanoparticles and the polymerisation conditions have favourable impacts on the broad-wave reflection of PSCLC films. To clarify the mechanism of formed broad-wave reflection, the morphology of nanofibers was observed by scanning electron microscopy (SEM). The modification of nanoparticles was collected by transmission electron microscopy (TEM) and infrared spectroscopy. The texture of PSCLC films was observed by POM. The broad-wave reflection were measured by UV-Vis spectrophotometer. This strategy broadens the broad-wave reflection of PSCLC films from 300 nm to 476 nm increasing its application potential in UV shielding devices, and infrared thermal control devices.

Nanocomposites of polyethylene with Fe3O4 nanoparticles via surface-initiated ROMP: Thermomechanical, shape memory and photothermal properties

The nanocomposites of polyethylene with Fe3O4 nanoparticles (NPs) were synthesized via surface-initiated ring-opening metathesis polymerization (SI-ROMP). First, the surfaces of pristine Fe3O4 NPs were functionalized with (5-nicyclo[2.2.1]hept-2-enyl)ethyl]triethoxylsilane. The as-obtained Fe3O4 NPs functionalized with norbornene were used to mediate the ROMP of cyclooctene (COE). By controlling the mass ratios of COE to the surface-functionalized Fe3O4 NPs, the polycyclooctene-grafted Fe3O4 NPs (denoted PCOE-g-Fe3O4 NPs) were obtained with variable contents of Fe3O4 NPs. Finally, these PCOE-g-Fe3O4 NPs were hydrogenated into the corresponding polyethylene-grafted Fe3O4 NPs (PE-g-Fe3O4 NPs). The nanocomposites of PE with Fe3O4 NPs were successfully synthesized as evidenced by the morphologies that the Fe3O4 NPs were well dispersed in PE matrix at the scale of nanometer. The nanocomposites displayed the mechanical properties superior to plain PE. More importantly, the nanocomposites were capable of displaying superparamagnetic, thermally-induced shape memory and photothermal properties. Furthermore, the photothermal behavior can be utilized to trigger the shape memory properties in a non-contact fashion.

Photocatalytic Degradation of Methylene Blue by Magnetic Opal/Fe3O4 Colloidal Crystals under Visible Light Irradiation

In this study, opal–magnetite photocatalysts based on SiO2 artificial opal crystals infiltrated with different concentrations of Fe3O4 nanoparticles (NPs) were synthesized using a combination of lateral infiltration and co-assembly methods. By adjusting the concentration of Fe3O4 NPs in the SiO2 opal crystal, the energy band gap (Eg) was tuned to enable efficient degradation of methylene blue (MB) under visible light (410 nm and 575 nm). The photocatalytic process involved two stages: MB adsorption on the surface due to charge differences in the composite film and subsequent degradation through oxidative radicals on the catalyst’s surface. The developed material exhibited potential for applications in water remediation.

Photocatalytic degradation of malachite green using PVDF membranes doped with Fe3O4 nanoparticles: role of porosity and surface roughness

We report on a cost-effective and time-efficient approach to synthesize flexible membranes of polyvinylidene fluoride (PVDF) doped with varying concentrations of Fe3O4 nanoparticles (FNP). The membranes exhibit a uniform dispersion of FNPs, a β-phase structure, and porous morphology, as confirmed by x-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) measurements. Fourier Transform-Infra Red (FTIR) and x-ray Photon spectroscopy (XPS) analysis was also performed for the identification of structural and chemical parameters of PVDF:FNP membranes. Photocatalytic degradation of malachite green (MG) dye under ultraviolet (UV) irradiation was assessed using the PVDF:FNP membranes. The results demonstrate a significant enhancement in the degradation efficiency and rate constant of the photocatalytic process with the utilization of PVDF:FNP membranes compared to FNP alone. Among the various concentrations tested, the PVDF membrane with 7% FNP doping exhibited the highest degradation efficiency of 98.39% and a notable apparent rate constant of 0.07048 min−1 in 60 min. The improved photocatalytic performance can be attributed to the larger surface area and enhanced accessibility of active sites in PVDF:FNP membranes, facilitating better control of the reaction environment and reducing the recombination rate of electron–hole pairs. This study suggests that PVDF:FNP membranes hold great promise for water purification applications, offering flexible membranes with superior degradation efficiency and enhanced reusability.

Effect of Fe3O4 Nanoparticles Modified by Citric and Oleic Acids on the Physicochemical and Magnetic Properties of Hybrid Electrospun P(VDF-TrFE) Scaffolds.

This study considers a fabrication of magnetoactive scaffolds based on a copolymer of vinylidene fluoride and trifluoroethylene (P(VDF-TrFE)) and 5, 10, and 15 wt.% of magnetite (Fe3O4) nanoparticles modified with citric (CA) and oleic (OA) acids by solution electrospinning. The synthesized Fe3O4-CA and Fe3O4-OA nanoparticles are similar in particle size and phase composition, but differ in zeta potential values and magnetic properties. Pure P(VDF-TrFE) scaffolds as well as composites with Fe3O4-CA and Fe3O4-OA nanoparticles demonstrate beads-free 1 μm fibers. According to scanning electron (SEM) and transmission electron (TEM) microscopy, fabricated P(VDF-TrFE) scaffolds filled with CA-modified Fe3O4 nanoparticles have a more homogeneous distribution of magnetic filler due to both the high stabilization ability of CA molecules and the affinity of Fe3O4-CA nanoparticles to the solvent used and P(VDF-TrFE) functional groups. The phase composition of pure and composite scaffolds includes a predominant piezoelectric β-phase, and a γ-phase, to a lesser extent. When adding Fe3O4-CA and Fe3O4-OA nanoparticles, there was no significant decrease in the degree of crystallinity of the P(VDF-TrFE), which, on the contrary, increased up to 76% in the case of composite scaffolds loaded with 15 wt.% of the magnetic fillers. Magnetic properties, mainly saturation magnetization (Ms), are in a good agreement with the content of Fe3O4 nanoparticles and show, among the known magnetoactive PVDF or P(VDF-TrFE) scaffolds, the highest Ms value, equal to 10.0 emu/g in the case of P(VDF-TrFE) composite with 15 wt.% of Fe3O4-CA nanoparticles.

Concurrent Dual-Contrast Enhancement Using Fe3O4 Nanoparticles to Achieve a CEST Signal Controllability.

Traditional T2 magnetic resonance imaging (MRI) contrast agents have defects inherent to negative contrast agents, while chemical exchange saturation transfer (CEST) contrast agents can quantify substances at trace concentrations. After reaching a certain concentration, iron-based contrast agents can "shut down" CEST signals. The application range of T2 contrast agents can be widened through a combination of CEST and T2 contrast agents, which has promising application prospects. The purpose of this study is to develop a T2 MRI negative contrast agent with a controllable size and to explore the feasibility of dual contrast enhancement by combining T2 with CEST contrast agents. The study was carried out in vitro with HCT-116 human colon cancer cells. A GE SIGNA Pioneer 3.0 T medical MRI scanner was used to acquire CEST images with different saturation radio-frequency powers (1.25/2.5/3.75/5 μT) by 2D spin echo-echo planar imaging (SE-EPI). Magnetic resonance image compilation (MAGiC) was acquired by a multidynamic multiecho 2D fast spin-echo sequence. The feasibility of this dual-contrast enhancement method was assessed by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, dynamic light scattering, ζ potential analysis, inductively coupled plasma, X-ray photoelectron spectroscopy, X-ray powder diffraction, vibrating-sample magnetometry, MRI, and a Cell Counting Kit-8 assay. The association between the transverse relaxation rate r2 and the pH of the iron-based contrast agents was analyzed by linear fitting, and the linear relationship between the CEST effect in different B1 fields and pH was analyzed by the ratio method. Fe3O4 nanoparticles (NPs) with a mean particle size of 82.6 ± 22.4 nm were prepared by a classical process, and their surface was successfully modified with -OH active functional groups. They exhibited self-aggregation in an acidic environment. The CEST effect was enhanced as the B1 field increased, and an in vitro pH map was successfully plotted using the ratio method. Fe3O4 NPs could stably serve as reference agents at different pH values. At a concentration of 30 μg/mL, Fe3O4 NPs "shut down" the CEST signals, but when the concentration of Fe3O4 NPs was less than 10 μg/mL, the two contrast agents coexisted. The prepared Fe3O4 NPs had almost no toxicity, and when their concentration rose to 200 μg/mL at pH 6.5 or 7.4, they did not reach the half-maximum inhibitory concentration (IC50). Fe3O4 magnetic NPs with a controllable size and no toxicity were successfully synthesized. By combining Fe3O4 NPs with a CEST contrast agent, the two contrast agents could be imaged simultaneously; at higher concentrations, the iron-based contrast agent "shut down" the CEST signal. An in vitro pH map was successfully plotted by the ratio method. CEST signal inhibition can be used to realize the pH mapping of solid tumors and the identification of tumor active components, thus providing a new imaging method for tumor efficacy evaluation.

Magneto-rheology control of cement paste containing Fe3O4 nanoparticles in view of reducing or preventing formwork leakage

Based on the principle of active stiffening control (ASC) of cementitious materials, a magnetic field-based active stiffening control methodology has recently been introduced to reduce formwork leakage under pressure. In the current study, this magnetic field-based methodology is applied to cement pastes containing Fe3O4 nanoparticles as the magnetisable components. The effects of Fe3O4 nanoparticle concentration, paste rheology, and applied pressure on the magnetic field-based formwork leakage control are investigated. The experimental results showed that the ASC method is effective in reducing the flow rate for formwork pressures of 10–50 kPa, and completely blocking the flow at 10–20 kPa. The ASC method was found to be more beneficial for the more flowable pastes, which generally exhibit more leakage in practice. The efficacy of the ASC method is also significantly influenced by the Fe3O4 nanoparticles concentration. The required amount of Fe3O4 nanoparticles for flow reduction should thus be selected accordingly. Additionally, the relative change in plastic viscosity (kμ) and storage modulus (kG’) due to the applied magnetic field could be used to reasonably estimate the flow reductions under magnetic field at 10–20 kPa. It is concluded that magneto-responsive additives are a suitable means in applying active stiffening control for formwork leakage reduction.

Modification of Fast-Growing Wood into Magnetic Wood with Impregnation Method Using Fe3O4 Nanoparticles

Fast-growing wood is rarely used by the community because of its low quality. This study aimed to modify the sengon (Falcataria moluccana) and jabon (Anthocephalus cadamba) into magnetic wood so they have new functions. In this study, the modification process was performed by impregnating five-level concentrations of Fe3O4 nanoparticles dissolved in two different dispersants, namely water and a mixture of furfuryl alcohol and water. The impregnation process is initiated by a vacuum of -0.5 bar, followed by a pressure of 1 bar for 120 min. The addition of furfuryl alcohol to the impregnation solution significantly increased the physical properties of magnetic wood. The presence of Fe3O4 in wood is also proven by the Fe-O groups observed from the FTIR spectrum analysis. The magnetic field strength also increased as the concentration level of Fe3O4 increased. Based on the results of this research, the best treatment was obtained on magnetic wood of sengon and jabon with furfuryl alcohol and Fe3O4 nanoparticles concentration of 7.5%. Keywords: Fast-growing wood, impregnation, magnetic wood, nanoparticles, nano Fe3O4

Replacing conventional iron with cysteine-coated Fe3O4 nanoparticles in soilless culture of strawberry

The present study was performed to investigate the response of strawberry cv. Ventana to different concentrations of cysteine-coated Fe3O4 nanoparticles under the hydroponic culture system. The experiment was conducted in a completely randomized design. The strawberry plants were treated with iron sulfate 6 mg.L−1 (as control) and cysteine-coated Fe3O4 iron nanoparticles at concentrations of 0.06 and 6 mg.L−1. The application of Fe3O4 nanoparticles at concentrations equal to and 100 times less than that of the conventional iron fertilizer resulted in an evident increase in the leaf and fruit Fe content of strawberry. Furthermore, chlorophyll pigments, total soluble carbohydrate, and total soluble protein increased with the implementation of cysteine-coated Fe3O4 nanoparticles with respect to the values for the conventional iron sulfate fertilizer. Moreover, the nanoparticles increased the dry weights of the root, crown, petiole, and leaf and total biomass with respect to those in the control. More importantly, the addition of iron nanoparticles to the nutrient solution to replace the conventional iron source led to an increase in yield. As a result, a significant positive relationship was observed between leaf iron content and yield. In addition, the strawberry plants treated with the nanoparticles exhibited improvements in total soluble solids, anthocyanin, flavonoid, phenol, and antioxidant capacity. It was concluded that cysteine-coated Fe3O4 nanoparticles at a concentration 100 times lower than that of conventional iron can be used not only for the nutrition of strawberry and the improvement of the vegetative and physiological traits, yield, and qualitative characteristics of the fruit but also for the production of iron-rich strawberry fruit.

Improving a solar collector's efficiency by selecting the composition of the working fluid used

Abstract The study's purpose was to determine the efficiency, as well as the energy and exergy analysis of the vacuum tube solar collector when using a mixture of water with Fe3O4 nanoparticles and multiwall carbon nanotubes in the selected percentage ratio as the working fluid. By varying the concentration of Fe3O4 nanoparticles in the working fluid from 0.05 to 0.15 wt.%, it was found that the maximum efficiency is achieved at a Fe3O4 content equal to 0.1 wt.%. At this concentration, the ratio of Fe3O4 and multiwall carbon nanotubes in the mixture varied from 4:1 to 1:4. It was found that the Fe3O4/multiwall carbon nanotubes ratio (1:4) can increase the efficiency of the solar collector up to 84%. Exergy analysis performed showed that water without the addition of nanoparticles Fe3O4 and multiwall carbon nanotubes was characterized by the maximum values of exergy destruction and entropy generation at any level of solar radiation, and water with the addition of nanoparticles Fe3O4/multiwall carbon nanotubes in a ratio of 1:4 was characterized by the minimum values of exergy destruction and entropy generation.