Properties of Iron Oxide Nanoparticles Synthesized at?Different?Temperatures

Iron oxide nanoparticles were synthesized by co-precipitation in air atmosphere at different temperatures and their structural and magnetic properties were investigated. The mean particle sizes of iron oxide nanoparticles were calculated from the X-ray diffraction (XRD) patterns using the Scherrer equation. Fourier transform infrared spectroscopy analysis exhibited the vibration bands at 563 cm^?1 and 620 cm^?1 confirming the formation of Fe₃O₄ and ??-Fe₂O₃, respectively. Morphological observation was made by a transmission electron microscope and the particle size of iron oxide nanoparticles was found to be around 9 nm which is consistent with the particle size calculated according to the XRD patterns. It was observed that the intensity of the peaks in the patterns and crystallinity increased as the temperature increased. Magnetization curves showed zero coercivities indicating that the samples are superparamagnetic.     

Effect of Oxide Assisted Metal Nanoparticles on Microstructure and Morphology of Gallium oxide Nanowires

Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD.     

Interactions of Mitoxantrone-Modified Superparamagnetic Iron Oxide Nanoparticles with Biomimetic Membranes and Cells

We report on the formation of conjugates of superparamagnetic iron nanoparticles(NPs)with the chemotherapeutic agent mitroxantrone(MTX).The NPs are synthesized from mixed iron oxides and are ca.15 nm in diameter.Decoration of the NP surface with MTX is accomplished with standard coupling chemistry techniques using sebacic acid as the coupling agent.The resulting NP-MTX conjugate is characterized thermogravimetrically,spectroscopically and electrochemically.The interactions of the NP-MTX conjugate with a model lipid layer formed as a Langmuir-Blodgett(LB)film reveal that the nanoparticle exhibits a significant perturbative effect on the layer,as seen from translational diffusion(FRAP)measurements.Evaluation of the cytotoxicity of the conjugate relative to that of free MTX demonstrates that the NP-MTX conjugate is more toxic than free MTX for both normal and malignant cell lines.These results underscore the importance of targeted delivery in the administration of chemotherapeutic agents.     

Development of Magnetocaloric Microstructures from Equiatomic Iron–Rhodium Nanoparticles through Laser Sintering

Pronounced magnetocaloric effects are typically observed in materials that often contain expensive and rare elements and are therefore costly to mass produce. However, they can rather be exploited on a small scale for miniaturized devices such as magnetic micro coolers, thermal sensors, and magnetic micropumps. Herein, a method is developed to generate magnetocaloric microstructures from an equiatomic iron–rhodium (FeRh) bulk target through a stepwise process. First, paramagnetic near-to-equiatomic solid-solution FeRh nanoparticles (NPs) are generated through picosecond (ps)-pulsed laser ablation in ethanol, which are then transformed into a printable ink and patterned using a continuous wave laser. Laser patterning not only leads to sintering of the NP ink but also triggers the phase transformation of the initial γ- to B2-FeRh. At a laser fluence of 246 J cm⁻², a partial (52%) phase transformation from γ- to B2-FeRh is obtained, resulting in a magnetization increase of 35 Am² kg⁻¹ across the antiferromagnetic to ferromagnetic phase transition. This represents a ca. sixfold enhancement compared to previous furnace-annealed FeRh ink. Finally, herein, the ability is demonstrated to create FeRh 2D structures with different geometries using laser sintering of magnetocaloric inks, which offers advantages such as micrometric spatial resolution, in situ annealing, and structure design flexibility.     

Synthesis of Silver Nanoparticles by a Laser–Liquid–Solid Interaction Technique

Silver nanoparticles of high chemical homogeneity have been synthesized by a novel laser–liquid–solid interaction technique from a solution composed of silver nitrate, distilled water, ethylene glycol, and diethylene glycol. Rotating nickel, niobium, stainless steel, and ceramic Al₂O₃ substrates were irradiated using a continuous-wave CO₂ laser and Q-switched Nd–YAG laser ( = 1064 and 532 nm). The silver nanoparticles were characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe x-ray microanalysis (EPMA). The shape of silver particles was dependent on the chemical composition and laser parameters. The synthesis mechanism of silver nanoparticles has been proposed to occur primarily at the laser–liquid–substrate interface by a nucleation and growth mechanism.     

Synthesis and Properties of Dextran–Nalidixic Acid Ester as a Colon-Specific Prodrug of Nalidixic Acid

Dextran–nalidixic acid ester (dextran-NA) with a varied degree of substitution (DS) was synthesized as a colon-specific prodrug of nalidixic acid (NA). Solubility in water (mg/ml) of dextran-NA with DS (mg NA/100 mg dextran-NA) of 7, 19, or 32 was 57.57 (equivalent to 4.00 mg NA/ml), 0.53 (equivalent to 0.10 mg NA/ml), or 0.03 (equivalent to 0.01 mg NA/ml), respectively, and that for NA was 0.03 at 25°C. To ensure the chemical stability of dextran-NA at conditions similar to those of the stomach and small intestine, dextran-NA was placed in a solution of pH 1.2 hydrochloric acid buffer or pH 6.8 phosphate buffer and incubated at 37°C; no NA was detected during the 6 h of the incubation period, which indicated that dextran-NA might be chemically stable during the transit through the gastrointestinal tract. Degree of depolymerization (%) by dextranase determined by the 2,4-dinitrosalicylic acid (DNS) method at 37°C for dextran-NA with DS of 7, 19, or 32 was 81, 68, or 8, respectively, in 8 h, and that for dextran was 91. When dextran-NA (equivalent to 50 μg of NA) with a DS of 7 or 17 was incubated with cecal contents (100 mg) of rats at 37°C, the extent of NA released in 24 h was 41% or 32% of the dose, respectively. NA was not liberated from the incubation of dextran-NA with the homogenate of tissue and contents of the small intestine.     

Control of the Synthesis of Composite Core–Shell-Type Particles in a Continuous Plasmachemical Reactor

Journal of Engineering Physics and Thermophysics - Characteristics of composite titanium dioxide and silicon dioxide nanoparticles with a structure of the core–shell type, synthesized by the...     

Synthesis and Characterization of Mixed Al+AlN Nanoparticles

Mixed Al+AlN nanoparticles were synthesized by an active plasma-metal reaction method. Mean particle size of the mixed Al+AlN nanoparticles is about 30-50 nm. Defects were found in some AlN particles. Moreover, the AlN ratio and its particle size in mixed Al+AIN nanoparticles obtained in different atmospheres (N2+Ar) increase with increasing N2 particle pressure, and the specific sudece areas of the mixed Al+AlN nanoparticles increase with the AlN ratio. The surface degradation of the Al+AlN exposed to air is estimated by the infrared absorption spectra     

CTAB Assisted Synthesis of CuS Microcrystals： Synthesis,Mechanism, and Electrical Properties

CuS microcrystals were successfully prepared through a mild solvothermal reaction in ethylene glycol （EG） with the assistance of cationic surfactant cetyltrimethylammonium bromide （CTAB）. An interesting morphology evolution from flower-like microspheres to hollow microspheres, and finally to smooth nanoflakes was observed when increasing the amount of CTAB. The products were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and UV-vis spectroscopy. It was found that the amount of CTAB played an important role in determining the morphology of the CuS microcrystals. Electrical measurement reveals that the as-prepared CuS microspheres were of high conductivity, which might favor their device applications. It is expected that CuS microcrystals with controlled morphologies and structures will have important applications in solar cells. This simple but effective method could also be extended to the controlled growth of other inorganic microcrystals.     

Characterization of Iron Oxide Generated in Ruthner Plant of Pickling Unit in Mobarakeh Steel Complex

Reducing the chloride content in regenerated iron oxides (RIO) from steel-pickling acid waste economically treated by Ruthner process is the most critical issue for the development of RIO as a useful raw material resource. In this paper, the results of a new method for characterization and modification of RIO produced in Mobarakeh Steel Complex were reported.     

Photoacoustic Measurement of Thermal Properties of Co–Ni–Li Ferrite Nanoparticles

A simple home-made open photoacoustic cell is used for measuring some of the thermal properties of nanoparticles of $\mathrm{{Co}}_{0.5}\mathrm{{Ni}}_{0.5\text{-- }2{x}}\mathrm{{Li}}_x\text{ Fe }_{2+{x}}\mathrm{{O}}_{4}$ Co 0.5 Ni 0.5 -- 2 x Li x Fe 2 + x O 4 (with $x$ x ranging from 0.00 to 0.25 in steps of 0.05) prepared by the citrate precursor method. The influence of sintering temperatures on the thermal properties of a selected sample for $x=0.25$ x = 0.25 was also investigated. The thermal-diffusivity and thermal-effusivity measurements of the investigated samples are obtained by measuring the photoacoustic signal as a function of the modulated frequency depending on the existence of a reference sample. The thermal diffusivity of the as-prepared samples decreases as the $\mathrm{{Li}}^{1+}$ Li 1 + content increases except for the samples for $x=0.15$ x = 0.15 and $x=0.20$ x = 0.20 . These exceptions may be due to a better magnetic ordering in these samples leading to reduced phonon scattering and a higher thermal diffusivity. Finally, the thermal diffusivity of the sintered samples increases as the sintering temperature increases due to the increase in grain size.     

Synthesis and Properties of Cerium Oxide Nanometer Powders by Pyrolysis of Amorphous Citrate

CeO2 nanometer powders of different sizes were prepared at low temperature by pyrolysis of amorphous citrate. XRD patterns show that CeO2 is cubic in structure, space group Oh5-FM3M·TEM indicates that the prepared CeO2 is spherical in shape, and the particle size distribution is in narrow range. It was found that calcination temperature is a more important factor affecting the crystallite size of CeO2 than calcining time, the smaller the particle. the bigger the crystallattice distortion, the worse the crystal growth. Solubility test of CeO2 in nitric acid reveals that the surface activity of CeO2 decreases with the increasing particle sizes. IR spectra analysis shows that the absorption of Ce-O bond is shifted to higher energy with the decrease of CeO2 particle sizes.     

Chemical Equilibrium and Critical Phenomena: The Solubilities of Iron(III) Oxide and Cobalt(II,III) Oxide in Isobutyric Acid + Water Near the Consolute Point

The solubilities of iron(III) oxide, formula Fe₂O₃, and cobalt(II,III) oxide, formula Co₃O₄, have been determined in the liquid mixture, isobutyric acid + water, along the critical isopleth at temperatures above the upper critical solution temperature near 299 K. When plotted in van’t Hoff form with ln s versus 1/T, the measurements of solubility, s, lie on a straight line for values of the temperature, T, in kelvin, which are sufficiently in excess of the critical solution temperature, T _c. The sign of the slope, (? ln s/?(1/T)), indicates that in the case of both oxides, the dissolution reaction is endothermic. When the temperature is within 1K of T _c, however, the slope departs from its constant value and appears to diverge toward negative infinity. The principle of critical-point universality predicts that a divergence in (? ln s/?(1/T)) is to be expected for T near T _c in those cases where the stoichiometry of the dissolution reaction involves both components of the solvent; moreover, the Gibbs–Helmholtz equation predicts that, if the heat of solution is endothermic, the sign of the divergence should be negative. Both of these predictions are confirmed by the solubilities of Fe₂O₃ and Co₃O₄ measured as a function of temperature along the critical isopleth of isobutyric acid + water.     

Transport Properties of Fullerene–Polyphenylene Oxide Homogeneous Membranes

Abstract

Fullerene–polyphenylene oxide (C₆₀–PPO) compositions containing up to 2 wt% C₆₀ were obtained and used for homogeneous membranes formation. Gas separation properties were estimated by measuring the permeability of individual gases H₂, O₂, N₂, CH₄, and CO₂. A correlation between gas permeability and free volume was established. The pervaporation of water/ethanol mixtures through fullerene‐containing membranes showed that C₆₀–PPO membranes exhibit dehydration properties. The degree of equilibrium sorption for PPO and C₆₀–PPO membranes in a water/ethanol system was estimated in the liquid phase. Gas separation and pervaporation properties were treated as a reflection of molecular interactions between PPO and C₆₀ molecules in compositions.     

Synthesis of Micron and Submicron Nickel and Nickel Oxide Particles by a Novel Laser–Liquid Interaction Process

The laser–liquid–solid interaction is a new technique for synthesis of nickel and nickel oxide particles. The process uses a continuous-wave CO₂ laser beam as the source of thermal energy required to induce precipitation reactions in solution. The uniqueness of the process is the synthesis reaction taking place in a localized region, which allows better control of the chemical reaction. Porous nickel and nickel oxide powders have been synthesized by laser-induced reactions between a nickel nitrate hexahydrate [Ni(NO₃)₂·6H₂O] precursor and 2-ethoxyethanol-based mixtures. Nickel powders were produced after irradiating a solution of the precursor salt and a 2-ethoxyethanol and d-sorbitol mixture. Crystalline nickel oxide (NiO) powders were isolated after irradiating a solution containing the precursor salt and a 2-ethoxyethanol and water mixture. Powders containing both nickel and nickel oxide crystalline phases were produced after irradiating a solution of the precursor salt and 2-ethoxyethanol. The mean particle diameter is found to be sensitive to irradiation time, substrate thermal conductivity, irradiation power density, and solution concentration. It is hypothesized that nucleation and growth of crystalline phases occurring in irradiated solutions are thermal driven.