Micromagnetics has been the method of choice to interpret experimental data in the area of microscopic magnetism for several decades. In this article, we show how progress has been made to extend ...this formalism to include thermal and quantum fluctuations in order to describe recent experimental developments in nanoscale magnetism. For experimental systems with constrained dimensions such as nanodots, atomic chains, nanowires, and thin films, topological defects such as solitons, vortices, skyrmions, and monopoles start to play an increasingly important role, all forming novel types of quasiparticles in patterned low-dimensional magnetic systems. We discuss in detail how soliton-antisoliton pairs of opposite chirality form non-uniform energy barriers against thermal fluctuations in nanowires or pillars. As a consequence of their low barrier energy compared to uniform reversal, they limit the thermal stability of perpendicular recording media. For sufficiently short samples, the non-uniform energy barrier continuously merges into the conventional uniform Néel-Brown barrier. Partial formation of chiral domain walls also determines the magnetic properties of granular nanostructured magnets and exchange spring systems. For a long time, the reconciliation between micromagnetics and quantum mechanics has remained an unresolved challenge. Here it is demonstrated how inclusion of Berry's phase in a micromagnetic action allows for a semiclassical quantization of spin systems, a method that is demonstrated by the simple example of an easy-plane spin. This powerful method allows for a description of quantum dynamics of solitons and breathers which in the latter case agrees with the anisotropic spin-½ XYZ-model. The domain wall or soliton chirality plays an important role as it is coupled to the wavevector of the quasiparticle dispersion. We show how this quantum soliton chirality is detected by polarized neutron scattering in one-dimensional quantum antiferromagnets.
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► An energy efficient synthesis of Fe
3O
4 nanoparticles. ► Annealing effect on morphology and magnetism of Fe
3O
4 nanoparticles. ► EPR study confirms the super paramagnetic nature ...of Fe
3O
4 nanoparticles. ► Activation energy and order of weight losses of Fe
3O
4 nanoparticles determined by TGA. ► Fe
3O
4 nanoparticles exhibit superior super paramagnetic properties.
The present article reports an energy efficient method for the synthesis of superparamagnetic ferrite (Fe
3O
4) nanoparticles (10–40
nm) and their annealing effect on the morphology, size, curie temperature and magnetic behavior at 50, 300, 400 and 500
°C. The synthesized nanoparticles were characterized by various spectroscopic techniques like FT-IR and UV–visible. The crystalline structure and particle size were estimated through solid phase as well as the liquid phase using XRD, TEM and DLS techniques. Superparamagnetic behavior of nanoparticles was confirmed by VSM. The EPR study reveals that the main feature of X-Band solid state EPR spectrum has strong transition at
g
eff
∼
3.23 (2100G) and a relatively weak transition at
g
eff
∼
2.05 (3300G). The later transition further confirms the super paramagnetic nature of these nano ferrites. The activation energy and order of weight losses of nano ferrites were found to be: 39.6
KJ
mol
−1 and 0.21 orders (600–800
°C), respectively, analyze with the help of TGA while the specific surface area (23.1
m
2
g
−1) and pore size (9
Å) were determined by Quanta chrome BET instrument.
Hyperthermia cancer atherapy designed by magnetic particles as heating nano-mediators has been greatly applied for in vitro purposes to make reliable and certain conditions for in vivo trials. This ...intracellular treatment has found higher efficiency as compared to conventional ones due to generating heat locally through superparamagnetic nanoparticles for inaccessible tumors with minimal damage to the healthy cells nearby. The main challenges of this novel cancer therapy are the enhancement of heating power of such nanoparticles and the control of the local tumoral temperature. Those hyperthermia factors basically derived from magnetic nanoparticles as well as magnetic field. Thereby, the efficiency of magnetic hyperthermia is principally dependent on the proper determination of their features. This study tried to provide a comprehensive evaluation on the magnetic hyperthermia therapy through the determination of magnetic nanoparticles such as surface chemistry, intrinsic and extrinsic magnetic properties. In addition, the features of the magnetic field that substantially play on induction heating power and hyperthermia temperature are reviewed.
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•The efficiency of magnetic nanofluid hyperthermia therapy as the induction heating power and temperature has been reviewed.•Magnetic alloys and metal oxides are the promising nanoparticles for hyperthermia therapy.•Core-shell structure and remaining the Curie temperature below 45°C are important to control the hyperthermia temperature.•The roles of the features of the magnetic field on the efficiency of hyperthermia therapy have been investigated.
•Recent advances on MnFe2O4 nanostructures for cancer theranostics are highlighted.•Physicochemical properties and surface functionalization strategies of MnFe2O4 are discussed.•Cytotoxicity study ...along with particular emphasis on their applications in cancer care are highlighted.•Current challenges and future trends MnFe2O4 nanostructures for cancer theranostics are proposed.
Over the past decade, transition metal-based ferrite nanostructures, displaying MFe2O4 stoichiometry (M2+ cations, e.g., Mn, Co, Ni and Zn), have been devised and examined primarily owing to their promising applications in cancer nanomedicine. Among these multi-functional spinel ferrites, manganese ferrite (MnFe2O4) deserves special attention because it unveils exciting magnetic properties, high chemical stability, and excellent biocompatibility, which are crucial prerequisites for advanced biomedical applications in solving real-world clinical problems. This review addresses MnFe2O4 nanostructures, including their numerous synthesis approaches, detailed physicochemical properties, surface functionalization strategies, cytotoxicity kinetics, along with a particular emphasis on their potential applications in advanced cancer care. Herein, we discuss diverse features of MnFe2O4 nanostructures, demonstrating both spherical and anisotropic morphologies and networks as futuristic cancer theranostic agents for efficient employment in magnetic resonance imaging (MRI), magnetic hyperthermia and targeted drug delivery in a safe, targeted and cost-efficient manner. Finally, future research trends and applications of MnFe2O4 nanostructures are also recommended and examined.
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•Hetero-structured nanofiber yarns (NFYs) is prepared by conjugate electrospinning.•NFYs own bifunctionality of color-tunable luminescence and superparamagnetism.•NFYs can be tuned in ...a wide color range of red-yellow-green.•Hetero-structure aids to reduce adverse interactions between various materials.•Strategy and method are used to prepare other multifunctional composite materials.
In this work, we have successfully fabricated hetero-structured nanofiber yarns (NFYs) with a conjugate electro-spinning technique, integrating a dual-functional capability of tunable color photoluminescence and tailored superparamagnetism. These hetero-structured NFYs are comprised of Eu(BA)3phen + Tb(BA)3phen/polyacrylonitrile (PAN) photoluminescent nanofibers (NFs) and Fe3O4/PAN superparamagnetic NFs, which allow for the effective isolation of dark-colored Fe3O4 nanoparticles (NPs) from rare earth complexes. This design leads to enhanced photoluminescent performance for the hetero-structured NFYs. Detailed investigations into the morphologies and performances of these NFYs were conducted using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), fluorescence spectrophotometry, and vibrating sample magnetometry (VSM). The emitting light color, ranging from red to yellow to green, can be tuned under a specific excitation wavelength (276 nm) of ultraviolet (UV) light by regulating the proportion of rare earth complexes. Furthermore, the superparamagnetism of the NFYs can be tailored by varying the amounts of Fe3O4 NPs. The designing philosophy and preparative technique can be utilized to manufacture other polyfunctional nanomaterials.
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We demonstrate magnetic resonance imaging (MRI) contrast enhancement and ac-field induced heating abilities of tetramethylammoniumhydroxide (TMAH) coated nickel ferrite (NiFe2O4) ...nanoparticles and discuss the underlying physical mechanisms. The structural characterization revealed that the NiFe2O4 particles synthesized with a modified co-precipitation method have a very narrow size distribution with a 4.4 nm magnetic core and 15 nm hydrodynamic diameters, with relatively small fraction of agglomerates. The as-prepared particles presented superparamagnetic behavior at room temperature. The in vitro hyperthermia experiments, performed in ac-field conditions under human tolerable limits, showed that the suspensions of the synthesized nanoparticles exhibit a maximum specific absorption rate (SAR) value of 11 W/g. The 1H nuclear magnetic resonance (NMR) relaxometry measurements indicated the suspensions of NiFe2O4 have a transverse-to-longitudinal relaxivity ratio r2/r1 greater than two, as required for superparamagnetic MRI contrast agents. On the basis of the parameters obtained from the magnetic measurements, by comparing the relevant theoretical models with the experimental results, we found that the presence of agglomerates, and particularly the interactions within the agglomerated nanoparticles, caused a significant increase in the hyperthermia and MRI efficiencies. On the other hand, from an applicative point of view, both the MRI contrast enhancement and the heating capabilities allow the simultaneous use of nickelferrites in diagnostic and therapeutic applications as theranostic agents.
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•Discusses attributes that make iron-based adsorbents suitable for U(VI) adsorption.•Categorization of adsorbents into inorganic, organic, MOF, and carbon-based types.•Deep discussion ...of physicochemical characteristics and U(VI) adsorption mechanism.•Focuses on the conditions required for advancing research in U(VI) adsorption.
Energy and environmental concerns have historically had an impact on the growth of civilization. In the last several decades, nuclear power has advanced rapidly since clean energy has proven to be convenient for storage. However, with an upsurge in nuclear power plants and the by-products they produce, noxious radioactive elements like uranium, which are harmful chemically and radiologically, have posed an imminent threat to aquatic and terrestrial life. Numerous approaches have been developed to deal with the shortcomings to maneuver these adversities. Among them, adsorption has been acknowledged as a simple, successful, and economically viable innovation that has received significant attention in recent years despite several limitations in terms of practical uses. In light of considerable investigations by several research organizations, medicine, catalysts, magnetic resonance imaging, and wastewater remediation represent merely some of the disciplines where iron-based adsorbents have garnered enormous curiosity. The application of these adsorbents to mitigate environmental pollutants has been steadily growing due to their superparamagnetism, low manufacturing expense, simplicity in modification, and biocompatibility. With the intent to objectively assess the potential for uranium removal in an ecologically safe manner, this review comprehensively explores various iron-based adsorbents (Fe-NAs), including inorganic, organic, metal–organic framework, and carbon-based materials. Furthermore, the article thoroughly investigates the synthesis processes and ways to enhance the surfaces of these adsorbents as well as delving into their fascinating physicochemical characteristics and adsorption mechanism. Finally, research prerequisites and prospective applications for future advancement have been highlighted. This review aims to furnish information that not only serves as a valuable reference but also ignites the spark of knowledge for researchers and professionals dedicated to this field.
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•A recyclable magnetic SDS-coated Fe3O4 promoter was designed and synthesized.•The promotional effect of bare Fe3O4 and SDS-coated Fe3O4 on hydrate formation was studied.•Comparison ...of cycle performance between bare Fe3O4 and SDS-coated Fe3O4 was conducted.•The mechanism of promotion during the cycle experiments with SDS-coated Fe3O4 was researched.
Gas hydrate has been proposed as an effective medium for gas separation, desalination, gas storage and so on, yet the low reaction rate has been hindering the industrialization of hydrate-based technology. Hence various kinds of promoters, especially nano particles, have been introduced and investigated to increase the rate of hydrate formation. However, the recyclability of these promoters has not been given sufficient attention from an environmental friendly and economic point of view. In this study, a recyclable magnetic Fe3O4 nanoparticle coated with SDS (SDS-coated Fe3O4) was synthesized and successfully used for hydrate formation promotion as well as cycle experiments. The results showed that SDS-coated Fe3O4 exhibited more efficient promotion for hydrate formation than bare Fe3O4 in the studied concentration range. Especially, the induction time and reaction time can be significantly reduced to 77.6 ± 24.1 and 36 ± 3 min, respectively, and the methane storage capacity can be maintained up to 130 ± 5.9 v/v with the concentration of 20 g/L SDS-coated Fe3O4. Further comparison of bare Fe3O4 and SDS-coated Fe3O4 during cycle experiments showed that after 5 cycles, the methane storage capacity and reaction time in presence of SDS-coated Fe3O4 can still be maintained as 119.5 ± 8 v/v and 110 ± 10 min, which were even better than the performance of bare Fe3O4 just after two cycles. To sum up, SDS-coated Fe3O4 can be recycled and reused many times for the hydrate formation, indicating that the SDS-coated Fe3O4 has a potential to increase the recyclability and its economy for promoters in the hydrate-based technology.
We report monodisperse, chain-like particles (nanochains) consisted of silica-coated maghemite (γ-Fe2O3) nanoparticle clusters prepared by colloidal chemistry and magnetic field-induced self-assembly ...of nanoparticle clusters. In order to quantify the shapes of chain-like particles, we have used the measure for shape convexity which is also called solidity. We functionalize the surface of the nanochains with amino (NH2) and carboxyl groups (COOH) in order to modify surface charge. These surfaces of nanochains provide better colloidal stability and their potential for practical applications in biomedicine. The enhanced colloidal stability of the surface modified nanochains is confirmed by Zeta potential (ζ-potential) analysis. Magnetic properties of the nanochains show superparamagnetic state at room temperature since the nanochains are composed of tiny nanoparticles as their building blocks. The measured M(H) data at room temperature have been successfully fitted by the Langevin function and magnetic moment μp = 20,526 μB for sphere-like nanoparticle clusters and μp = 20,767 μB for nanochains are determined. The determined magnetic parameters have revealed that the nanochains show a magnetic moment of the nanoparticles higher than the one of individual nanoparticle clusters. These differences can be attributed to the collective magnetic properties of superparamagnetic iron oxide nanoparticles (SPION) assembled in different morphologies (isotropic and anisotropic morphology).
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•Uniform maghemite nanochains are synthesized by colloidal chemistry.•Shape of the nanochains is quantified by easily computable solidity measure.•Magnetic measurements of the nanochains show superparamagnetic properties.•Magnetic properties point to the shape anisotropy of the nanochains.
Purpose: The main purpose of this publication is to bring closer co-precipitation method of magnetic particles synthesis. Procedure of examining and characterisation of those materials was also ...shown. Design/methodology/approach: During the work, the properties and possible biomedical application of the material produced were also examined. Surface morphology studies of the obtained particles were made using Zeiss's Supra 35 scanning electron microscope and S/TEM TITAN 80-300 transmission electron microscope. In order to confirm the chemical composition of observed layers, qualitative tests were performed by means of spectroscopy of scattered X-ray energy using the Energy Dispersive Spectrometer (EDS). The Raman spectra of the samples were measured with a InVia Raman microscope by Renishaw. Magnetic properties of hematite nanoparticles were made using VSM magnetometer. Findings: Using VSM magnetometer proved that obtained material is mixture of ferromagnetic and superparamagnetic domain. Practical implications: Magnetic Nanoparticles (MNPs) has been gaining an incrementally increasing interest of scientists in the biomedical areas. Presented materials can be used in the hyperthermia phenomena which can be used in precise cancer treatment. Originality/value: Specific magnetic properties which determinate obtained material to be well for hyperthermia phenomena.
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