• Journal of Magnetics
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• v.10 no.1
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• pp.5-9
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• 2005

Nanoparticles $Ni_{0.9}Zn_{0.1}Fe_2O_4$ is fabricated by a sol-gel method. The magnetic and structural properties of powders were investigated with XRD, SEM, Mossbauer spectroscopy, and VSM. $Ni_{0.9}Zn_{0.1}Fe_2O_4$ powders annealed at $300{^{\circ}C}$ have a spinel structure and behaved superparamagnetically. The estimated size of $Ni_{0.9}Zn_{0.1}Fe_2O_4$ nanoparticle is about 10 nm. The hyperfine fields at 13 K for the A and B patterns are found to be 533 and 507 kOe, respectively. The ZFC curves are rounded at the blocking temperature ($T_B$)and show a paramagnetic-like behavior above $T_B$. $T_B$ of $Ni_{0.9}Zn_{0.1}Fe_2O_4$ nanoparticle is about 250 K. Nanoparticles $Ni_{0.9}Zn_{0.1}Fe_2O_4$ annealed at 400 and $500{^{\circ}C}$ have a typical spinel structure and is ferrimagnetic in nature. The isomer shifts indicate that the iron ions were ferric at the tetrahedral (A) and the octahedral (B). The saturation magnetization of nanoparticles $Ni_{0.9}Zn_{0.1}Fe_2O_4$ annealed at 400 and $500{^{\circ}C}$ are 40 and 43 emu/g, respectively. The magnetic anisotropy constant of $Ni_{0.9}Zn_{0.1}Fe_2O_4$ annealed at $300{^{\circ}C}$ were calculated to be 1.6 ${\times}$ $10^6$ ergs/$cm^3$.

• Journal of Microbiology and Biotechnology
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• v.15 no.2
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• pp.254-258
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• 2005

We have conducted in vitro reconstitution study of ferritin from its subunits FerH and FerL. For the reconstitution, FerH was produced from an expression vector construct in Escherichia coli and was purified from a heat treated cell extract by using one-step column chromatography. FerL was expressed as inclusion bodies. The denatured form of FerL was obtained by a simple washing step of the inclusion bodies with 3 M urea. The reconstitution experiment was conducted with various molar ratios of urea-denatured FerH and FerL to make the ferritin nanoparticle with a controlled composition of FerH and FerL. SDS-PAGE analysis of the reconstituted ferritins revealed that the reconstitution required the presence of more than 40 molar$\%$ of FerH in the reconstitution mixture. The assembly of the subunits into the ferritin nanoparticle was confmned by the presence of spherical particles with diameter of 10 nm by the atomic force microscopic image. Further analysis of the particles by using a transmission electron microscope revealed that the reconstituted particles exhibited different percentages of population with dense iron core. The reconstituted ferritin nanoparticles made with molar ratios of [FerH]/[FerL]=l00/0 and 60/40 showed that 80 to $90\%$ of the particles were apoferritin, devoid of iron core. On the contrary, all the particles formed with [FerH]/[FerL]=85/ 15 were found to contain the iron core. This suggests that although FerH can uptake iron, a minor portion of FerL, not exceeding $40\%$ at most, is required to deposit iron inside the particle.

• Journal of the Korean Magnetics Society
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• v.24 no.5
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• pp.135-139
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• 2014

Iron-oxide nanopowders were synthesized by a pulsed wire evaporation (PWE) in various ambient gas conditions. SEM measurement indicates that the spherical iron nanoparticles are about 50 nm in diameter. The phase analysis for the produced iron-oxide powders was systematically investigated by using $M\ddot{o}ssbauer$ spectra and the results show that classified phases of $Fe_2O_3$ and $Fe_3O_4$ can be controlled by regulating the oxygen concentration in the mixed gas during the PWE process. A quadrupole line on the center of $M\ddot{o}ssbauer$ spectrum represents the superparamagnetic phase of 12 % from ${\gamma}-Fe_2O_3$ phase.

• Journal of the Korean Magnetics Society
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• v.20 no.6
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• pp.216-221
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• 2010

Magnetic nanocomposites contained iron oxide were synthesized by through cross-linking polymerization of dimethylacetamide (DMAc) solution and toluen solution on the amphiphilic polymer networks based on urethan acrylate nonionomer (UAN) precursor chains. For the study on microscopic structures and magnetic properties of the magnetic nanoparticles, FESEM and XRD and Mossbauer spectroscopy were used. The results investigated show that there are magnetic nanoparticles of $Fe_2O_3$ in samples and the magnetic nanocomposites contained iron oxide in polymer networks of UAN using DMAc solution are more smaller than using toluen solution. All of the Fe ions in the samples present $Fe^{3+}$ and the magnetic property of samples are paramagnetic by superparamagnetic effect at room temperature.

• Biomedical Science Letters
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• v.29 no.4
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• pp.211-219
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• 2023

Caffeic acid phenethyl ester (CAPE) is an active component of propolis obtained from honeybee hives. CAPE possesses anti-mitogenic, anti-carcinogenic, anti-inflammatory, and immunomodulatory activities in diverse systems, which know as displays antioxidant activity and inhibits lipoxygenase activities, protein tyrosine kinase, and nuclear factor kappa B (NF-κB) activation. This study aimed to investigate the effect of CAPE on lipopolysaccharide (LPS)-induced human neutrophil phagocytosis. Human neutrophils were cultured with various concentrations of CAPE (1, 10, and 100 µM) with or without LPS. The pro-inflammatory proteins (tumor necrosis factor-alpha [TNF-α], interleukin [IL]-6 and IL-8) levels were measured after 4 h incubation. To investigate the intracellular signaling pathway, we measured the levels of mitogen-activated protein kinases (MAPK), including phosphorylation of p38, extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) and c-Jun N-terminal kinase (JNK). Next, to evaluate the potential phagocytosis, neutrophils were labeled with iron particles of superparamagnetic iron oxide nanoparticles (SPIONs, 40 nm) for 1 h in culture medium containing 5 mg/mL of iron. The labeling efficiency was determined by Prussian blue staining for intracellular iron and 3T-wighted magnetic resonance imaging. CAPE decreased the activation of intracellular signaling pathways, including ERK1/2 and c-Jun, and expression of pro-inflammatory cytokines, including TNF-α and IL-6, but had no effect on the signaling pathways of p38 and cytokine IL-8. Furthermore, images obtained after mannan-coated SPION treatment suggested that CAPE induced significantly higher signal intensities than the control or LPS group. Together, these results suggest that CAPE regulates LPS-mediated activation of human neutrophils to reduce phagocytosis.

• Journal of Magnetics
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• v.20 no.4
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• pp.371-376
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• 2015

Magnetite nanoparticles were synthesized by adding excess ammonium hydroxide to a solution of iron (II) and (III) chlorides. The surfactants of oleic acid and Span 80 were applied in sequence to the magnetic particles as a combined stabilizer, and poly-${\alpha}$-olefin (PAO) 30 or 60 was used as the liquid base with a low or high viscosity, respectively. The ferrofluids were prepared with the concentrations of 200, 300, 400, and 500 mg/mL, and characterized by density, dispersion, magnetization, and viscosity. The density of the fluids increased proportionally to the concentration from 0.98 to 1.27 g/mL and 1.01 to 1.30 g/mL with PAO 30 base and PAO 60 base, and the dispersion stability was 77-95 and 81-74% for the PAO-30 and PAO-60-based fluids, respectively. The observed saturation magnetization values of the PAO-30 and PAO-60-based ferrofluids were 16 to 42 mT and 17 to 41 mT with the concentration increase in the range 200-500 mg/mL, respectively, depending upon the content of magnetic particles in the fluid. The viscosity variation of the PAO-30 and PAO-60-based ferrofluids in the temperature range $20-80^{\circ}C$ was the least with the concentrations of 400 and 300 mg/mL, respectively.

• Journal of Magnetics
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• v.14 no.2
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• pp.75-79
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• 2009

Nickel (Ni) and ferrite ($Fe_3O_4$, $NiFe_2O_4$) nanoparticles were synthesized by LGC using both wire feeding (WF) and micron powder feeding (MPF) systems. Phase evolution and magnetic properties were then investigated. The Ni nanopowder included magnetic-ordered phases. The LGC synthesis yielded spherical particles with large coercivity while the abnormal initial magnetization curve for Ni indicated a non-collinear magnetic structure between the core and surface layer of the particles. Since the XRD pattern cannot actually distinguish between magnetite ($Fe_3O_4$) and maghemite (${\gamma}-Fe_2O_3$) as they have a spinel type structure, the phase of the iron oxide in the samples was unveiled by $M{\ddot{o}}ssbauer$ spectroscopy. The synthesized Ni-ferrite consisted of single domain particles, including an unusual ionic state. The synthesized nanopowder bore an active surface due to the defects that affected abnormal magnetic properties.

• Journal of the Korean Ceramic Society
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• v.51 no.6
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• pp.570-574
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• 2014

Magnetic-graphene nanosheets have been synthesized via a simple effective chemical precipitation method followed by heat treatment. The composite nanosheets are super paramagnetic at room temperature and can be separated by an external magnetic field. The prepared magnetic-graphene nanosheets were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and BET surface area analysis. The results demonstrated the successful attachment of iron oxide nanoparticles to graphene nanosheets. It was found that the attached nanoparticles were mainly $Fe_3O_4$. The magnetic-graphene nanosheets showed near complete methyl orange removal within 10 mintues and would be practically usable for methyl orange separation from water.

• Journal of Magnetics
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• v.10 no.3
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• pp.84-88
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• 2005

Nanoparticles $Ni_{0.7}Zn_{0.3}Fe_2O_4$ is fabricated by a sol-gel method. The magnetic and structural properties of powders were investigated with XRD, SEM, $M\ddot{o}ssbauer$ spectroscopy, and VSM. $Ni_{0.7}Zn_{0.3}Fe_2O_4$ powders annealed at $300^{\circ}C$ have a spinel structure and behaved superparamagnetically. The estimated size of $Ni_{0.7}Zn_{0.3}Fe_2O_4$ nanoparticle is about 11 nm. $Ni_{0.7}Zn_{0.3}Fe_2O_4$ annealed at 400 and $500^{\circ}C$ has a typical spinel structure and is ferrimagnetic in nature. The isomer shifts indicate that the iron ions were ferric at the tetrahedral (A) and the octahedral (B). Blocking temperature $(T_B)\;of\;Ni_{0.7}Zn_{0.3}Fe_2O_4$ nanoparticle is about 260 K. The magnetic anisotropy constant of $Ni_{0.7}Zn_{0.3}Fe_2O_4$ annealed $300^{\circ}C$ were calculated to be $1.7X10^6\;ergs/cm^3$. Also, temperature of the sample increased up to $43^{\circ}C$ within 7 minutes under AC magnetic field of 7 MHz.

• Journal of Hydrogen and New Energy
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• v.33 no.6
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• pp.715-722
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• 2022

Pt-Fe/carbon black nanocatalysts were prepared by spontaneous reduction reaction of Platinum(II) acetylacetonate and Iron(II) acetylacetonate in a nucleophilic solvent and they were characterized by scanning electron microscopy (SEM), energy dispersive X-ray analyzer (EDS), thermogravimetric analyzer (TGA), transmission electron microscopy (TEM), Brunauer, Emmett and Teller (BET) surface area analysis and anion exchange membrane (AEM) water electrolysis test station. The distribution of the Pt and Fe nanoparticles on carbon black was observed by TEM, and the loading weight of Pt-Fe nanocatalysts on the carbon black was measured by TGA. Elemental ratio of Fe:Pt was estimated by EDS and it was found that elemental ratio of Pt and Fe was changed in the range of 1:0 to 0:1, and the loading weight of Pt-Fe nanoparticles on the carbon black was 5.95-6.78 wt%. Specific surface area was greatly reduced because Pt-Fe nanocatalysts blocked the pores. I-V characteristics were estimated.