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This work presents a comprehensive analysis of the magnetic properties of pristine and citric acid-coated cobalt ferrite (${\rm{CoF}}{{\rm{e}}_{\rm{2}}}{{\rm{O}}_{\rm{4}}}$ CoF e 2 O 4 ) nanoparticles (NPs) dispersed in the host nematic $4{^{\prime}}$ 4 ′ -heptyl-4-biphenylcarbonnitrile (7CB) system. Our results shed light on the promising potential of combining liquid crystals (LC) with magnetic nanoparticles for cancer treatment. This opens up exciting avenues for further exploration and possible applications in the field of oncology. The study focuses on examining the magnetic behaviour of LC dispersed systems with two concentrations of magnetic nanoparticles (0.03 and 0.04 wt%). Notably, intriguing temperature-dependent magnetisation plots reveal a distinctive cusp, which can be attributed to the freezing phenomenon of the liquid crystal. This observation offers valuable insights into the system's magnetic properties and interactions, deepening our understanding of its behavior. [ABSTRACT FROM AUTHOR]

Abstract The present work focuses on the in-situ synthesis of Fe3O4/rGO magnetic nanocomposite by using leaf extract of Azadirachta indica as a reducing agent. Morphology and EDX studies indicate that the rGO array and Fe3O4 nanoparticles have effectively cooperated with each other. XRD analysis confirms a high crystallinity cubic structural phase with a crystallite size of about 7.48 nm. FTIR spectroscopy confirms the strong Fe-O stretching bonding. UV-Visible spectroscopy reveals the formation of rGO and iron oxide nanoparticles with the tunable energy bandgap of 2.52 eV, which is calculated using the Tauc plot. VSM analysis confirms the superparamagnetic nature of nanocomposite with approximate magnetization (Ms) 47.36 emu/g. The TGA study confirms the higher thermal stability of the synthesized nanocomposite as compared to rGO and Fe3O4 nanoparticles. It is expected that the synthesized Fe3O4/rGO nanocomposite, an eco-friendly and nontoxic material may be used in various advanced applications. [ABSTRACT FROM AUTHOR]

In this study, nanocrystalline Ni100-xCux alloy films have been synthesised using DC magnetron co-sputtering under argon gas atmosphere to analyse their superparamagnetic behaviour. The nanocrystalline nature and the grain size of the alloy films have been measured using grazing incidence x-ray diffraction (GIXRD) and a transmission electron microscopy (TEM). The M-H curves obtained using superconducting quantum interference device provides evidence for superparamagnetic behaviour of the nanocrystalline Ni100-xCux alloy films. For the Ni89Cu11 alloy films, the highest value (456 emu/cm3) of saturation magnetisation has been measured. Zero field cooling (ZFC) and field cooling (FC) data obtained from superconducting quantum interference device (SQUID) showed the dependence of blocking temperature, TB on Cu concentration of the investigated NiCu alloy. The blocking temperature is observed to decrease from 44 K to 33 K with increase in Cu concentration from 11 to 28 wt%. [ABSTRACT FROM AUTHOR]

The ferrimagnetic mixed-spin ternary nanoisland models with two and three layer structures were set up by the Ising model with spin quantum numbers 1, 3/2 and 1/2. Using the transfer matrix method, we got the magnetization, magnetic susceptibility and ground-state diagram exactly. The results show that the magnetic susceptibility of nanoisland with two-layer structure shows antiferromagnetic behavior, while that of nanoisland with three-layer structure shows antiferromagnetic or ferromagnetic behavior in different parameter areas. The antiferromagnetic behavior shows that the net spin of the ground-state system is zero. The ferromagnetic behavior shows that the magnetic susceptibility diverges at zero temperature, the Curie constant is proportional to the square of the net spin in the ground-state configuration of spins. The magnetization of the three-layer structure in an external magnetic field shows superparamagnetic behavior with many magnetization plateaus. It can be inferred that there should be similar results for finite Ising nanosystems. [ABSTRACT FROM AUTHOR]

Synthesis, structural features, and paramagnetic properties of manganese-containing nanocomposites based on polysaccharides arabinogalactan, sulfated arabinogalactan, and κ-carrageenan have been studied. All compounds have been investigated by physical and chemical methods including electron paramagnetic resonance, transmission electron microscopy, infrared spectroscopy, and atomic absorption analysis. It is shown that manganese-containing nanoparticles of 3–6 nm in size were stabilized in the polysaccharide mass by coordination with Mn2+, and the resulting particles have a complex structural organization and are highly EPR active with a spin concentration of about 1020 spin/g. The obtained nanocomposites possess aggregative stability and conserve their properties for a long time. [ABSTRACT FROM AUTHOR]

Co0.1Fe0.9S2 nanoparticles were synthesized by solvothermal method and studied by Mössbauer spectroscopy in the cooling process. Magnetic phase transition can be testified by Mössbauer investigation. The spectrum recorded at room temperature consists of a simple quadrupole doublet, the values of isomer shift and quadrupole splitting of doublet increase gradually with the decrease of temperature. However, the spectrum consists of a sextet when the temperature drops further to 25 K, indicating that the sample changed from paramagnetism to ferromagnetism. The magnetic field at low temperature is probably super-transferred field from the magnetically ordered cobalt atoms through a super-exchange mechanism. [ABSTRACT FROM AUTHOR]

Zn1–xCoxO nanoparticles have been prepared by coprecipitation method. X-ray diffraction study confirms the polycrstalline nature with hexagonal wurtzite ZnO structure of the Zn1–xCoxO nanoparticles. The W–H analysis results confirms the mean crystallite size of the Co-doped samples was increased from 62 to 72 nm. All samples have nanocrystalline particles were investigated by field emission scanning electron microscopy. Optical absorption studies showed a red shift absorption spectra due to the incorporation of Co atoms in ZnO lattice. Dielectric constant and dielectric loss were decreasing with increasing Co content. Magnetic hysteresis loops of prepared nanoparticles exhibit paramagnetic behavior at room temperature. [ABSTRACT FROM AUTHOR]

A disubstituted polyacetylene with lyotropic liquid crystallinity showing SmA was synthesized. The number-average-molecular weight of the polymer was 5.2 × 105 g/mol. Vapor phase iodine doping for the disubstituted polyacetylene in the form of liquid crystal order allows the generation of charge carriers. The ESR measurements show the charge carriers exhibit Pauli paramagnetism, indicating that these carriers are polarons. Mott-type variable range hopping (VRH) conduction of the polymer was observed. The combination of SmA molecular architecture and electrical conduction by polyene as a molecular wire in the polyacetylene derivative results in liquid crystal electrical conduction via electro-soliton movement. [ABSTRACT FROM AUTHOR]

Fe3O4 nanoparticles with a particle size of approximately 16.5 nm were prepared by the chemical coprecipitation method with the raw materials of ferric chloride, ferrous chloride, and sodium hydroxide. The optimum reaction conditions were determined by the single factor control method; then, magnetic polymer nanoparticles were produced by microemulsion polymerization, and the synthesis conditions were optimized by orthogonal experiments with four factors and three levels. As expected, spherical particles of approximately 60 nm were obtained. The morphology, structure, and properties of the product were characterized and analyzed. The results showed that the particles possessed a uniform spherical shape, good thermal stability, and superparamagnetism, which will ensure these particles have a wide application of directional flooding profile control. Average EOR of magnetic polymer nanospheres with magnetic field was 14.41 wt%. The magnetized magnetic polymer nanospheres had better profile control ability, and were less damage to the low permeability layer. Separation experiment showed that magnetized magnetic polymer nanospheres can be effectively separated due to the low viscosity and the good magnetism. Furthermore, the separated polymer nanospheres can be reused again. [ABSTRACT FROM AUTHOR]

In this study, the nano-sized water droplets (NWDs) in water-in-oil (W/O) emulsion were employed as mini-reactors, in which Fe3O4/PAM magnetic nano-hydrogels (MNHs) were obtained based on the coprecipitation and inverse emulsion polymerization. In addition, compound nonionic surfactant was used as the stabilizer of W/O emulsion. The test results showed that Fe3O4/PAM MNHs were quasi-sphere particles with a diameter of about 50–380 nm and had superparamagnetism. The percentage of PAM coating Fe3O4 was about 81%. The saturation magnetization of the Fe3O4/PAM MNHs was 21.6 emu/g (Fe3O4/AM (wt/wt) = 16.63%). The W/O emulsion containing Fe3O4/PAM MNHs (E-2) changed from fluid to solidlike in an external magnetic field. As current intensified or shear rate increased, the shear stress of E-2 increased. [ABSTRACT FROM AUTHOR]

We consider a Potts model on a Cayley tree with competing nearest-neighbor and next-nearest-neighbor interactions restricted to spins belonging to the same branch of the tree with four spins and investigate the problem of phase transition for paramagnetic phases of this model. [ABSTRACT FROM AUTHOR]

We have studied the magnetization of a recently synthesized CuS compound and found two phase transitions around room temperature. The phase transitions in the crystalline structure, characterized by XRD studies, are accompanied by changes also in the electrical resistivity. A hysteretic first-order phase transition has been found between 260 and 320 K, from a low-temperature paramagnetic anilite phase to a diamagnetic high-temperature low-digenite phase. A second order phase transition was recognized at ≃ 352 K from low digenite to a paramagnetic high-digenite structure at high temperatures. [ABSTRACT FROM AUTHOR]

The geometrical structures and magnetic properties of (n = 2-6) magnetic clusters have been systematically investigated using Monte Carlo simulations. The transitions temperatures are deduced from the thermal magnetisation and magnetic susceptibility of for different size. The effect of crystal fields and exchange interactions on the magnetisation has been investigated. Magnetic hysteresis cycles with different clusters, temperatures and exchange interactions are obtained. Superparamagnetism in cobalt clusters has been observed. [ABSTRACT FROM AUTHOR]

Two iron(II)-rhenium(IV) compounds of general formula [FeII(dmf)6][ReIVX6] [X = Cl (1) and Br (2); dmf = N,N-dimethylformamide] have been prepared and characterized. X-ray powder diffraction measurements on samples of 1 and 2 support the same structure for both systems. The crystal structure of 1 was determined by single-crystal X-ray diffraction. 1 crystallizes in the triclinic system with space group Pī. Each iron(II) is six-coordinate and bonded to six oxygens from six dmf molecules building a distorted octahedral environment. Rhenium(IV) is six-coordinate by six halide anions in an almost regular octahedral geometry. The magnetic properties were investigated from variable-temperature magnetic susceptibility measurements performed on microcrystalline samples of 1 and 2, whose experimental data were reproduced by a model of two isolated paramagnetic centers [S = 2 (FeII) and S = 3/2 (ReIV)] with large values of zero-field splitting (zfs) parameter. [ABSTRACT FROM AUTHOR]

In this study, we report about the preparation of magnetic polymer nanocomposites on the basis of isotactic polypropylene and magnetite Fe3O4nanoparticles. The structure and composition of polymer nanocomposite materials have been studied by scanning electron microscopy, atomic force microscopy, and X-ray dispersive analysis. The magnetic properties of polymer nanocomposites based on PP+Fe3O4have been investigated. It is found that not significant adhesion and agglomeration of nanoparticles occur, by increasing the nanoparticle content in polymer matrix up to 40%, and therefore they act as single-domain nanoparticles. The samples of nanocomposites based on PP+Fe3O4, with up to 40% content of Fe3O4, exhibit superparamagnetic properties. It was also found out that the magnetic polymer nanocomposite material based on PP+Fe3O4is able to absorb ultrahigh frequency electromagnetic waves in the frequencies range from 0.1 to 30 GHz. The increase in Fe3O4concentration from 5 to 40% at the 400 µm thicknesses of the films leads to an increase in absorption of electromagnetic waves of high frequency from 15 to 22.7%. [ABSTRACT FROM AUTHOR]

In vivo decay rates of a nitroxyl contrast agent were estimated by a MR redox imaging (MRRI) technique and compared with the decay rates obtained by the electron paramagnetic resonance spectroscopy (EPRS) and imaging (EPRI). MRRI is a dynamic imaging technique employing T1-weighted pulse sequence, which can visualise a nitroxyl-induced enhancement of signal intensity by T1-weighted contrast. EPR techniques can directly measure the paramagnetic nitroxyl radical. Both the squamous cell carcinoma (SCC) tumour-bearing and normal legs of a female C3H mouse were scanned by T1-weighted SPGR sequence at 4.7 T with the nitroxyl radical, carbamoyl-proxyl (CmP), as the contrast agent. Similarly, the time course of CmP in normal muscle and tumour tissues was obtained using a 700-MHz EPR spectrometer with a surface coil. The time course imaging of CmP was also performed by 300 MHz CW EPR imager. EPRS and EPRI gave slower decay rates of CmP compared to the MRRI. Relatively slow decay rate at peripheral region of the tumour tissues, which was found in the image obtained by MRRI, may contribute to the slower decay rates observed by EPRS and/or the EPRI measurements. To reliably determine the tissue redox status from the reduction rates of nitroxyls such as CmP, heterogenic structure in the tumour tissue must be considered. The high spatial and temporal resolution of T1-weighted MRI and the T1-enhancing capabilities of nitroxyls support the use of this method to map tissue redox status which can be a useful biomarker to guide appropriate treatments based on the tumour microenvironment. [ABSTRACT FROM AUTHOR]

This paper describes a green one-pot synthesis of L-Serine (L-Ser) capped magnetite nanoparticles (Fe3O4NPs) and its potential application for adsorption of RhB dye from aqueous solution. The surface property, structure, morphology and magnetic properties of as prepared L-Ser capped Fe3O4NPs were characterised through UV-Visible spectroscopy, Fourier transform-infrared spectroscopy, X-Ray Diffraction (XRD), scanning electron microscope, transmission electron microscope (TEM) and vibrating sample magnetometer (VSM). The XRD results were indicated the formation of high crystalline spinel type Fe3O4NPs. TEM images were shown the spherical shape of L-Ser capped Fe3O4NPs with particle size of 5.9 nm. The VSM curve showed the superparamagnetic behaviour of L-Ser capped Fe3O4. A plausible interaction mechanism of L-Ser and Fe3O4NPs was also investigated. L-Ser capped Fe3O4NPs due to its large surface area and a strong magnetism was shown potential adsorption efficiency towards RhB dye from aqueous solution. The adsorption isotherm data fitted well with Langmuir isotherm model and the monolayer adsorption capacity (qe,exp) was found to be 6.82 mg/g at pH 7.4 and 300 K. The experimental kinetic data fitted very well with the pseudo-second-order model. The thermodynamic studies reveal that adsorption efficiency is critically dependent on temperature. [ABSTRACT FROM AUTHOR]

Magnesium nano ferrite substituted with Yttrium and Samarium is synthesized by Sol Gel Auto Combustion method by optimising the sintering temperature and its duration to achieve pure Spinel Phase without any impurity. Particle size obtained from XRD and TEM are in close agreement with each other. Saturation magnetization of Mg-nanoferrite is moderate at room temperature which decreases by substitution of Y &Sm. Magnetic results are further authenticated by Mössbauer Spectroscopic analysis. Experimental results are explained on the basis of existing theories and Models. Magnesium ferrite (substituted with Y &Sm) is chosen because of its potential application in biomedical fields e.g, hyperthermia treatment, drug delivery and even for antibacterial activity. [ABSTRACT FROM AUTHOR]

Fe3O4nanoparticles were synthesized by a facile one-pot hydrothermal process just using ferric citrate and water without any additional reagent and post-treatment. The temperature of hydrothermal reaction had important influence on the crystallinity and magnetic property of Fe3O4samples. Fe3O4sample synthesized at 200 °C for 24 h showed a narrow size distribution (4 to 8 nm in diameter), and exhibited apparent superparamagnetism with saturated magnetization of 55.1 emu/g. The narrow size distribution and superparamagnetism were the interesting features of these Fe3O4nanoparticles. [ABSTRACT FROM PUBLISHER]

The effect of oxygen conditioning on the performance of polyaniline (PANI) membranes is presented and discussed. The presence of the conditioning effect in such kind of polymer matrix was confirmed by measuring a variation in spin concentration using electron paramagnetic resonance (EPR) spectroscopy. The observed decrease in spin concentration indicates the presence of the dissolved oxygen incompletely removed from PANI matrix. After the prolonged contact between oxygen and PANI membrane, a pronounced decrease in membrane’s selectivity was observed, which may be explained by the firm and permanent interaction between oxygen molecules and nitrogen paramagnetic centers of PANI and could be considered as a kind of PANI irreversible doping process. [ABSTRACT FROM PUBLISHER]

The labeling of cells with nanomaterials for tumor detection is a very important part of various biomedical applications. In this study, multilayer nanocomposites were synthesized to achieve the multiple functions of fluorescence, magnetism, and bioaffinity. Firstly, superparamagnetic Fe3O4nanoparticles were prepared as a magnetic core. Then, fluorescein isothiocyanate (FITC) was covalently linked to the surface of the silica-coated Fe3O4core (designated FMNPs). Finally, bovine serum albumin (BSA) was conjugated onto the FMNPs (designated FMNPs-BSA). We also evaluated the feasibility and efficiency of labeling the human liver cancer cell line SMMC-7721 (SMMC-7721) with nanocomposites. SEM, hysteresis loop, EDS, FTIR, fluorescence spectra, and fluorescence microscopy were used to determine the physicochemical properties of nanocomposites. Fluorescence microscopy, SEM-EDS, and TEM were used to determine fluorescence labeling, absorption, and uptake respectively. The results showed that the nanocomposites obtained exhibited fine superparamagnetism, strong fluorescence, and good biological affinity. We succeeded in using the new multilayer nanocomposites to label cells, which had properties of magnetic targeting and fluorescent tracing. [ABSTRACT FROM PUBLISHER]

We investigated the antioxidant activities and locations of stable paramagnetic species in dry (or drying) shiitake mushroom (Lentinus edodes) using continuous wave (CW) electron paramagnetic resonance (EPR) and 9 GHz EPR imaging. CW 9 GHz EPR detected paramagnetic species (peak-to-peak linewidth (ΔHpp) = 0.57 mT) in the mushroom. Two-dimensional imaging of the sharp line using a 9 GHz EPR imager showed that the species were located in the cap and shortened stem portions of the mushroom. No other location of the species was found in the mushroom. However, radical locations and concentrations varied along the cap of the mushroom. The 9 GHz EPR imaging determined the exact location of stable paramagnetic species in the shiitake mushroom. Distilled water extracts of the pigmented cap surface and the inner cap of the mushroom showed similar antioxidant activities that reduced an aqueous solution of 0.1 mM 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl. The present results suggest that the antioxidant activities of the edible mushroom extracts are much weaker than those of ascorbic acid. Thus, CW EPR and EPR imaging revealed the location and distribution of stable paramagnetic species and the antioxidant activities in the shiitake mushroom for the first time. [ABSTRACT FROM PUBLISHER]

We have synthesized a racemic and enantiomerically enriched all-organic paramagnetic nitroxide radical (NR) liquid crystalline (LC) compound, which contains a chiral NR unit in the mesogen core and a methyl di(ethylene glycol) chain as one of their terminal units. These new compounds showed remarkable substituent effects of the methyl di(ethylene glycol) chain on the phase transition behaviors and hydrophilic properties in contrast to structural analogs of the previous reported NR-LC compounds containing alkoxy chains. [ABSTRACT FROM AUTHOR]

The current article reports on providing surface modification of magnetic nanoparticles with gold to provide stability against aggregation. Gold-coated magnetite nanoparticles were synthesised to combine both magnetic as well as surface plasma resonance (SPR) properties in a single moiety. The nanocomposites were produced by reduction (using ascorbic acid) of gold chloride on to the surface of iron oxide nanoparticles. Ascorbic acid not only acts as a reducing agent, but also the oxidised form of ascorbic acid i.e. Dehydro-ascorbic acid acts as a capping agent to impart stability to as synthesised gold-coated iron oxide nanocomposites. The synthesised nanocomposite was monodispersed with a mean particle size of around 16 nm and polydispersity index of 0.190. X-ray diffraction analysis confirms presence of gold on the surface of magnetite nanoparticles. The synthesised nanocomposites had a total organic content of around 3.2% w/w and also showed a shifted SPR peak at 546 nm as compared to gold nanoparticles (528 nm). Both uncoated and gold-coated magnetite exhibited superparamagnetic behaviour at room temperature. Upon coating with gold shell, saturation magnetisation of iron oxide nanoparticles decreases from 42.806 to 3.54 emu/gram. [ABSTRACT FROM PUBLISHER]

The study of the structural, morphology and magnetic properties of Zn0.5Co0.5Fe2O4ferrite is the objective of this work. The sample was prepared by hydrothermal method and was characterized by X-ray diffraction (XRD), (SEM) and (TEM) micrographs and magnetization measurements. The magnetic hysteresis loops, field cooling (FC) and zero field cooling (ZFC) curves, in temperature range (0-400K), were measured using XL-SQUID magnetometer and the values of blocking temperatures (TB) were determined. The results indicated that Zn0.5Co0.5Fe2O4sample were formed in a single spinel phase and gives the value for the lattice parameter (8.3952 Å) and nanosizes of particles (13.8 nm) were compared with these obtained from ZnFe2O4sample prepared also by synthesis method (8.4261 Å and 14 nm). Although, the superparamagnetic behaviour for Co-Zn ferrite has observed at 350K with a blocking temperature (TB= 300K), that is maximum at the value obtained in the case of Zn-ferrite (TB= 12K). [ABSTRACT FROM AUTHOR]

Synthesis, structural, and magnetochemical characterization of the tetranuclear [Ni4O4] heterocubane cluster [NiCl(L1)(MeOH)]4,1, employing the bidentateN,O-ligand 2-hydroxymethyl-2-oxazoline,HL1, is reported. In the solid state, each nickel(II) is coordinated in a distorted octahedral environment, located on four corners of a [Ni4(μ3-O)4] cubane core motif. Measurements of the magnetic susceptibility in solution (Evans method) as well as in the solid state (magnetic susceptibility balance) gave values of 5.74 and 6.08 unpaired electrons, respectively, indicating a spin ground state ofS = 3. At maximum spin degeneracy (S = 4), eight unpaired electrons would be expected. Magnetic properties were further evaluated by SQUID measurements of1, confirming the spin ground state of1to beS = 3. The observed deviation is caused by antiferromagnetic coupling between the four Ni atoms. In addition, broken-symmetry DFT calculations confirmed an overlap of magnetic orbitals resulting in exchange coupling between the four nickel(II) ions of1. [ABSTRACT FROM AUTHOR]

Gamma irradiated powders of glycine anhydride and betaine hydrochloride have been investigated at room temperature by electron paramagnetic resonance (EPR). In these compounds, the observed paramagnetic species were attributed to the R1 and R2 radicals, respectively. It was determined that the free electron interacted with environmental protons and14N nucleus in both radicals. The EPR spectra of gamma irradiated powder samples remained unchanged at room temperature for two weeks after irradiation. Also, the Fourier Transform Infrared (FT-IR), FT-Raman and thermal analyses of both compounds were investigated. The functional groups in the molecular structures of glycine anhydride and betaine hydrochloride were identified by vibrational spectroscopies (FT-IR and FT-Raman). [ABSTRACT FROM AUTHOR]

The Ruddlesden-Popper (RP3) type oxides, La4Co3O10+δ and La4Ni3O10+δ, form a complete solid solution. Powder X-ray and neutron diffraction data show that La4(Co1-xNix)3O10+δ is isostructural to the monoclinic La4Co3O10+δ structure (P21/a) described for all compositions without any further structural distortions as suggested in the literature. A slight elongation of the Co/Ni-O bonds facing the rock salt interlayer occurs for Ni-rich compositions. The magnetic properties of the solid solution series are mapped in the temperature range from 4 to 300 K, and the results are presented in a magnetic phase diagram. Three regimes with antiferromagnetic order (AF) exist at low temperatures, TN < 10 - 30 K. For x = 0.00, the AF is ascribed to Co(II), whereas a broader AF regime around x = 0.50 is ascribed mainly to Ni(II). Pauli paramagnetism is observed close to metallic La4Ni3O10+δ, x > 0.80. The possibility to tune the oxidation state of the transition metal atoms is demonstrated for La4Co3O10+δ, and exemplified by weakening of a temperatureinduced spin transition at around 480 K. [ABSTRACT FROM AUTHOR]

Water-soluble γ-Fe2O3/polyvinylpyrrolidone (PVP) nanoparticles were obtained by transferring oleic acid (OA) coated iron-oxide nanocrystals from hexane to water. The particle size of the γ-Fe2O3/PVP nanoparticles with excellent monodispersity is about 14 nm. Fourier transform-infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) results indicate that PVP anchors on the γ-Fe2O3 nanoparticles through its carbonyl group and provided sufficient hydrophilicity. The maghemite content in the γ-Fe2O3/PVP nanoparticles was about 81 wt-%. The saturation magnetisation of the superparamagnetic γ-Fe2O3/PVP nanoparticles is 57·7 emu g− 1 at 295 K. For in vivo magnetic resonance imaging (MRI) studies, the γ-Fe2O3/PVP nanoparticles can be guided to the target area by a permanent magnet and show negative contrast enhancement on the target area of laboratory mice. [ABSTRACT FROM AUTHOR]

We have synthesized a new series of all-organic paramagnetic liquid crystalline (LC) compounds, which include a five-membered ring nitroxide radical (NR) moiety in the mesogen core and fluorine atoms as terminal substituents. These new compounds are the structural analogs of the previously reported NR-LC compounds, and showed remarkable fluorine substituent effects. The introducing fluorine atom into terminal unit stabilizes nematic phase. However, an excess of fluorination leads to the destabilization of nematic phase. [ABSTRACT FROM AUTHOR]

Objective. The clinical data considering the bone marrow mononuclear cell (BMMNC) therapy in treatment for acute myocardial infarction (AMI) are controversial and the mechanisms remain unknown. Our objective was to study the cardiac function and changes in cytokine levels after administration of BMMNC in experimental AMI model. Design. Unlabeled or Super-Paramagnetic-Iron-Oxide-labeled BMMNCs or saline was injected into myocardium of 31 pigs after circumflex artery occlusion. Ejection fraction (EF) was measured preoperatively, postoperatively and at 21 days by echocardiography. Cardiac MRI was performed postoperatively and after 21 days in 7 BMMNC animals. Serum cytokine levels were measured at baseline, 24 h and 21 days. Cellular homing was evaluated comparing MRI and histology. Results. From baseline to 21 days EF decreased less in BMMNC group (EF mean control -19 SD 12 vs. BMMNC -4 SD 15 percentage points p = 0.02). Cytokine concentrations showed high variability between the animals. MRI correlated with histology in cell detection and revealed BMMNCs in the infarction area. By MRI, EF improved 11 percentage points. The improvement in EF was associated with the number of transplanted BMMNCs detected in the myocardium. Conclusion. BMMNC injection after AMI improved cardiac function. Quantity of transplanted BMMNCs correlated with the improvement in cardiac function after AMI. [ABSTRACT FROM AUTHOR]

New magnetic polyamide/Fe3O4nanocomposites containing pendent 9H-xanthene were prepared via solution intercalation technique from polyamide9and Fe3O4nanoparticle in a solution ofN,N-dimethylacetamide. A new polyamide9as a source of polymeric matrix was synthesized by direct polycondensation reaction of 3,5-diamino-N-(4-(1,3,6,8-tetramethyl-9H-xanthen-9-yl)phenyl)benzamide (7) with adipic acid in a medium consisting ofN-methyl-2-pyrrolidone, triphenyl phosphite, calcium chloride, and pyridine. The synthesized polyamide was characterized by Fourier transform infrared spectra, nuclear magnetic resonance, UV–vis, and photoluminescence spectroscopy. The structural and electronic properties of xanthene-based polyamide unit were studied by ab initio density functional theory method using the B3LYP/6-31G (d) level of theory. The highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LOMO) level energy, and band gap (ΔE = ELUMO − EHOMO) of the polyamide unit were calculated. Fe3O4nanoparticles have been synthesized using a chemical co-precipitation route. Using a combination of dissolving the polymer and mixing Fe3O4nanoparticles, we have demonstrated the formation of nanocomposites with uniform nanoparticle dispersion. The morphology, crystalline phase, thermal stability, and magnetization properties of the resultant materials were characterized by means of transmission electron microscope, X-ray diffraction, thermal gravimetric analysis, and vibrating sample magnetometer. The results indicated that the as-prepared nanocomposites exhibited superparamagnetic properties and improvements in the thermal stability compared to neat polyamide. [ABSTRACT FROM AUTHOR]

Chitosan nanoparticles with magnetic properties can be potentially used as separation materials in the adsorption of oil for enhanced oil recovery. Different from traditional surfactants, the novel magnetic CoFe2O4–chitosan nanoparticles have the advantages of excellent biodegradation and a high level of controllability. The CoFe2O4–chitosan nanoparticles with core–shell structure were prepared successfully. The images of transmission electron microscopy and scanning electron microscopy showed that the cube-shaped magnetic CoFe2O4particles were encapsulated by the spherical chitosan nanoparticles. The sizes of the CoFe2O4–chitosan nanoparticles were all below 100 nm. The saturated magnetization of the CoFe2O4–chitosan nanoparticles could reach 80 emu/g and showed the characteristics of superparamagnetism at the same time. The evaluation of the interfacial properties of the product showed that the interfacial tension between crude oil and water could be reduced to ultra-low values—as low as 10−3mN/m—when magnetic CoFe2O4–chitosan nanoparticle was used in several blocks in the Shengli Oilfield without other additives. Meanwhile, the magnetic CoFe2O4–chitosan nanoparticles possessed good salt-resisting capacity. [ABSTRACT FROM AUTHOR]

A brief review of selected experimental photoemission works on URu2Si2spanning almost 25 years is presented. We focus on the areas of importance for both the paramagnetic (PM) and hidden-order (HO) phases, where photoemission provides direct and strong evidence for: (i) f–d hybridization, (ii) presence of hybridization gap, (iii) details of the massive reconstruction of FS upon transition and (iv) a non-integer valence likely close to 2.6. While most of the FS reconstruction details have been mapped and are now known, the most recent high resolution and low temperature ARPES studies reveal novel electronic structure features related to HO. No single ARPES experiment so far captures all of the phases appearing in this system as temperature is lowered. [ABSTRACT FROM PUBLISHER]

Composite materials are used in all kinds of engineering structures, medical prosthetic devices, sensors and electromagnetic interference shields and so on. The γ-Fe2O3/polyaniline-Mesna (γ-Fe2O3/PANI-Mesna) composite with conducting and superparamagnetic characters is synthesised in an aqueous hydrochloric acid solution (0·2 mol L−1) containing aniline, 1-ethyl-3-methylimidazolium ethyl sulphate (EMIES) and γ-iron sesquioxide (γ-Fe2O3) by using mesna as a dopant and ammonium persulfate [(NH4)2S2O8] as an oxidant. Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD) and transmission electron microscope (TEM) have been used to characterise the γ-Fe2O3/PANI-Mesna composite and to confirm that mesna is doped into γ-Fe2O3/PANI chains. The cyclic voltammetry (CV) and magnetisation studies show that γ-Fe2O3/PANI-Mesna composite has the superparamagnetism (14 emu g−1) and electrochemical activity at pH 4-8. The study provides an academic foundation for developing some new material for immobilising drugs of anticancer. [ABSTRACT FROM AUTHOR]

The electron paramagnetic resonance (EPR) parameters (gfactorsgxx,gyy,gzzand hyperfine structure constantsAxx,Ayy,Azz) are interpreted by taking account of the admixture of d-orbitals in the ground state wave function of the Cu2+ion in a Zn(C3H3O4)2(H2O)2(DABMZ) single crystal. Based on the calculation, local structural parameters of the impurity Cu2+center were obtained (i.e. Ra≈1.92 Å,Rb≈1.96 Å,Rc≈1.99 Å). The theoretical EPR parameters based on the above Cu2+−O2−bond lengths in the DABMZ crystal show good agreement with the observed values and some improvements have been made as compared with those in the previous studies. [ABSTRACT FROM AUTHOR]

In this work, polyaniline (PANI) nanorods and magnetite (Fe3O4) nanoparticles have been synthesised by using ammonium persulphate as oxidant viain-situchemical oxidative polymerisation of aniline in presence of excess of organic sulphonic acid. The resulting PANI/Fe3O4nanocomposites materials were characterised using X-ray diffraction, UV-visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, vibrating sampling magnetometer and thermogravimetric analysis. Spectroscopic results indicated the successful formation of PANI/Fe3O4nanocomposites. As obtained, PANI/Fe3O4nanocomposites have Fe3O4particle size in the range of 3.2–7 nm. Morphologies of PANI/Fe3O4nanocomposites were found to be dependent on the molar ratio of aniline to organic acid. Under certain polymerisation conditions, PANI rods like structures were obtained. PANI/Fe3O4nanocomposites have superparamagnetism and higher thermal stability. [ABSTRACT FROM PUBLISHER]

We present an introduction to the workings, units of measure, and general properties of magnetic materials. This is intended as a “primer to interpretation of magnetic data” for those who are entering the field, or those who are encountering magnetic measurements in the literature. We expect this work will serve as an initial guide to the reader to familiarize them with the basics in the hope that those working in the field of magnetochemistry will wish to explore additional, more detailed literature as their specific investigations demand. Topics covered include: magnetic fields and units (SI and cgs), paramagnetism (magnetization and magnetic susceptibility), Curie and Curie–Weiss behavior, magnetic exchange interactions, magnetic anisotropy, dimeric systems and exchange-coupled networks (including chains, ladders, and layers), and long-range order. [ABSTRACT FROM AUTHOR]

β-Glucosidase fromTrichoderma reeseiwas immobilised on synthetic superparamagnetic magnetite (Fe3O4) nanoparticles with a mean diameter of 10 nm and were used to supplement cellulase in the enzymatic hydrolysis of three substrates: wheat straw pretreated by steam explosion,Eucalyptus globuluspretreated by hydrothermolysis andE. globuluspretreated by hydrothermolysis followed by alkaline extraction. The hydrolysis yields for each pretreated material, using immobilisedβ-glucosidase (I-βG) and free cellulase, were 76.1%, 83.6% and 75.6%, respectively, and resulted in an improved hydrolysis yields compared with only cellulase. These yields were at most 10% lower than yields reached with free enzymes. The (I-βG) was magnetically recovered and successfully reused twice. The differences in the hydrolysis yields were not significant (p > 0.05) in the case of steam-exploded wheat straw andE. globuluspretreated by hydrothermolysis followed by alkaline extraction. The immobilisation of enzymes provides an opportunity to reduce the costs of enzymes in the bioethanol production process. [ABSTRACT FROM AUTHOR]

This review analyses the advances in the field of magnetically induced cell death using intracellular magnetic nanoparticles (MNPs). Emphasis has been given to in vitro research results, discussing the action of radiofrequency (RF) waves on biological systems as well as those results of thermally induced cell death in terms of MNP cell interactions. Our main goal has been to provide a unified depiction of many recent experiments and theoretical models relevant to the effect of applied electromagnetic fields on MNPs after cellular uptake and the cytotoxicity assessment of MNPs. We have addressed the effects of RF waves used for in vitro magnetic hyperthermia on eukaryotic cells regarding physical modifications of the cellular local environment and cell viability. [ABSTRACT FROM AUTHOR]

Five cyanide complexes, [Ni(N-bishydeten)Pd(CN)4] (1), [Cu(N-bishydeten)Pd(μ-CN)2(CN)2]n(2), [Cu(N-bishydeten)2][Pd(CN)4] (3), [Zn(N-bishydeten)Pd(CN)4] (4), and [Cd(N-bishydeten)2][Pd(CN)4] (5) (N-bishydeten=N,N-bis(2-hydroxyethyl)-ethylenediamine), have been synthesized and characterized using various techniques. Different structures were formed when the M : L ratio was varied in copper complexes. The single-crystal X-ray diffraction analysis reveals that2, a 1-D cyanide-bridged complex with 2,2-CT-typezigzagchain, was obtained by using 1 : 1 M : L ratio whereas3was formed as a complex salt in a molar ratio of 1 : 2. The thermal stabilities determined from DTGmaxvalues of the first decomposition stages change in the order1 > 5 > 4 > 3 > 2. Although an EPR signal was not observed for1, thegparameters obtained from the EPR spectra of2and3indicate that CuIIions are located in tetragonally distorted octahedral sites (D4h), and the ground state of the unpaired electron is(2B1g). The magnetic behavior indicates a very small antiferromagnetic interaction below 10 K for1–3. In3, there is a temperature-independent paramagnetism (α) due to the orbital moments of thedelectrons.1–3were tested as catalysts in Suzuki and Heck coupling reactions. [ABSTRACT FROM AUTHOR]

The present investigation aims at studying the effect of swift heavy ion irradiation on the structural, magnetic and dielectric properties of the nanocrystalline Cu0.2Zn0.8Fe2O4spinel ferrite. The sample was synthesised using the sol–gel technique and then irradiated with the 200 MeV Ag+15ion beam. The Rietveld profile refinement of the X-ray diffraction patterns confirmed the cubic spinel structure of samples. The spherical morphology revealed through transmission electron microscopy images was consistent with the crystalline diameter. The overall magnetic behaviour pointed towards superparamagnetic relaxation at room temperature along with the significant increase in saturation magnetisation, coercivity and blocking temperature after irradiation. This could be attributed to the slight increase in the particle size and ion-induced modifications on the surface states of the nanoparticles. The enhancement in dielectric constant and loss tangent after irradiation could be attributed to the available Fe+2↔ Fe+3and/or Zn+2↔ Zn+3ion polarisation at the octahedral site, especially on grain boundaries of the sample. [ABSTRACT FROM AUTHOR]

Nanocrystalline samples of ZnCr0.4Fe1.6O4ferrite were synthesized by the advanced sol–gel method to investigate the effect of 200 MeV Ag+15ion irradiation on the cation distribution, magnetic and dielectric properties. Rietveld profile refinement of the X-ray diffraction (XRD) patterns confirms the single-phase cubic spinel structure of the specimens. The irradiated sample retains the cubic spinel structure with a slight increase in the lattice parameters and the average crystallite size. Temperature- and field-dependent dc magnetization studies show an appreciable enhancement in the saturation magnetization and blocking temperature of the irradiated samples, which could be attributed to the slight increase in the particle size due to the heat evolved during irradiation. Subsequently, the rearrangement of cations in the lattice structure and the ion-induced modifications on the surface states of the nanoparticles could be accountable. The room temperature dielectric constant and the loss tangent in the frequency range 75 kHz–10 MHz revealed the normal frequency dispersion. The increase in ϵrand tan δ on irradiation could be attributed to the slight crystal growth and hence the availability of the sufficient number of Fe2+and/or Zn3+ions particularly at the octahedral site on the grain boundaries, showing a fair agreement with the magnetization results. [ABSTRACT FROM AUTHOR]

Exchange-correlation density functionals at the meta-generalised gradient approximation level typically use the Kohn–Sham orbitals as an ingredient to create the isoorbital indicator, whereis the von Weizsäcker kinetic energy density andis the kinetic energy density of the Kohn–Sham orbitals. When a magnetic field is included in the treatment, the Kohn–Sham orbitals vary with the vector-potential gauge, as doesand implicitly the exchange-correlation energy. However, it is a known result in current density functional theory that the exact exchange-correlation energy is gauge independent. Three different gauge-independent replacements forhave been proposed by other authors. Only one of these is, however, known to stay between 0 and 1. We modify one of the others, the Maximoff–Scuseria isoorbital indicator, so that it also stays between 0 and 1. We investigate the ability of the isoorbital indicators evaluated in a system with densityand paramagnetic current densityto reproduce the value ofin a system having no paramagnetic current, but the same density. We provide the first example known to us where the Tao–Perdew isoorbital indicator goes outside of the interval from 0 to 1. [ABSTRACT FROM AUTHOR]

Paramagnetic, dipolar Hund's case-a radicals are considered in the presence of arbitrary, non-collinear combinations of electric and magnetic fields. The field-dependent part of the Hamiltonian is found to exhibit a good quantum number, consisting of the projection of the molecule's total angular momentum along a space-fixed axis that is determined by both the fields and the electric and magnetic dipole moments of the molecule. This quantity remains good even when the fields are non-collinear. Exploiting this feature identifies a set of quantum numbers for the molecule in crossed fields. We dub this set a 'Hund's case-X' basis. [ABSTRACT FROM AUTHOR]

In the present study, ZnFe2O4nanoparticles were synthesized by the chemical co-precipitation followed by calcinations at 473 and 673 K for 4 h. Particle sizes obtained were 4 and 6 nm for the calcination temperatures of 473 and 673 K, respectively. To study the origin of system’s low temperature spin dynamic behaviour, temperature dependence of susceptibilitywas investigated as a function of particle size and frequency. Slight increase in the grain size from 4 nm at 473 K to 6 nm at 673 K has led to a peak shift of temperature dependence of susceptibility measured at a constant frequency of 400 Hz. Temperature dependence ofat different frequencies also resulted in peak shift. Relaxation time dependence of peak temperature obeys a power law, which provides the fitting parameters within the range of superparamagnetic nature of the particles. Further, dependence of relaxation time and peak temperature obeys Vogel–Fulcher law rather than Néel–Brown equation demonstrating that the particles follow the behaviour of superparamagnetism of slightly interacting system. Spin–lattice,T1and spin–spin,T2relaxivity of proton of the water molecule in the presence of chitosan-coated superparamagnetic ZnFe2O4nanoparticle yields the values of 0.002 and 0.360 s−1 per ppm. [ABSTRACT FROM AUTHOR]

We present a detailed structural study of tensile-strained La0.7Sr0.3MnO3thin films. We use the substratemiscutto control the number of rhombohedral variants in the films and study the in-plane order and structural distortions. Using high-resolution X-ray diffraction, we demonstrate that step-edge induced lattice modulations occur in 4-variant films, whereas periodic twinning is the dominant in-plane order for 2-variant films. We show that the in-plane twinning angle is almost completely relaxed. However, the relaxation of shear strain by the out-of-plane twinning angle and the monoclinic distortion is only partial. Furthermore, the film thickness dependence of the domain width reveals that domain formation is a universal mechanism for shear strain relaxation. Finally, we show that the structural response to the transition from the paramagnetic to the ferromagnetic phase of La0.7Sr0.3MnO3at 345 K is smaller in 4-variant films compared to 2-variant films. [ABSTRACT FROM AUTHOR]

Recent developments in spectrally encoded microspheres (SEMs)-based technologies provide high multiplexing possibilities. Most SEMs-based assays require a flow cytometer with sophisticated fluidics and optics. A new imaging super-paramagnetic SEMs-based alternative platform transports SEMs with considerably less fluid volume into a measuring chamber. Once there SEMs are held in a monolayer by a magnet. Light-emitting diodes (LEDs) are focused on the chamber to illuminate the SEMs – instead of lasers and they are imaged by a charge-coupled device (CCD) detector, offering a more compact sized, transportable and affordable system. The feasibility of utilising this system to develop a 3-plex SEMs-based imaging immunoassay (IMIA) for the screening of persistent organic pollutants (POPs) was studied. Moreover the performance characteristics of 3-plex IMIA were critically compared with the conventional 3-plex flow cytometric immunoassay (FCIA). Both SEM technologies have potential for the multiplex analysis of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and polycyclic aromatic hydrocarbons (PAHs) in buffer and fish extract with insignificant differences in assay sensitivities. Furthermore, we developed a faster and simpler, modified QuEChERS-like generic POPs extraction from tilapia fillet using sodium hydrogen carbonate as one of the salt additives and dispersive solid-phase extraction (dSPE) as a clean-up. Finally, a preliminary in-house validation using 40 different blank and spiked tilapia fillet samples was performed in both systems and the results obtained were critically compared. The lower-cost imaging SEMs-based system performed similarly to the original flow cytometer and, in combination with the new quicker QuEChERS-like extraction, it has high potential for future rapid screening of POPs in several other sample matrices such as other fish species, vegetable refined oils and environmental samples. [ABSTRACT FROM AUTHOR]

Broadband dielectric spectroscopy measurements revealed an anomalously large relative permittivity value (ε r = 884) for MnPr2W2O10, a smaller value (ε r = 156) for CoPr2W2O10 and the smallest value (ε r = 22) for CdPr2W2O10 at low frequency (ν = 0.1 Hz) and above room temperature in the insulating and paramagnetic state. Below 273 K, the relative permittivity (ε r ∼ 24) did not depend significantly on frequency for all the tungstates under study. Electrical resistivity, thermoelectric power, electron paramagnetic resonance, magnetic susceptibility and magnetization provided experimental evidence that the studies tungstates were paramagnetic insulators with low n-type conduction. Only in the case of MnPr2W2O10 was a ferrimagnetic order below 45 K observed. These effects are discussed within the framework of Maxwell–Wagner polarization, chemical covalent bonds and porosity mechanism. [ABSTRACT FROM AUTHOR]

We report preparation of polyaniline (PANI) with radicals on theN-positions. Chirality of a PANI having optically active substituent is retained even upon oxidation bym-chloroperoxybenzoic acid in chloroform to generate spin species. Electron spin resonance and circular dichroism spectroscopy measurements suggest that the chiral paramagnetic properties of PANIs are derived from the combination of chiral side chains and oxyradicals in the structure of the polymer. This report focuses on a new synthetic approach for obtaining magneto-optically active polyanilines. [ABSTRACT FROM PUBLISHER]