Magnetic Investigation of Various NiFe<Subscript>2−<Emphasis Type="Italic">x</Emphasis></Subscript>Bi<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>4</Subscript> Ferrite Nanostructures Synthesized by Ball Milling Technique

NiFe_2?x Bi _x O₄ (x = 0, 0.1, 0.2, 0.3) nanoparticles with various grain sizes were synthesized via annealing treatment followed by ball milling of its bulk component materials. Commercially available bismuth, nickel and iron oxide powders were first mixed and then annealed at 1200 °C in an oxygen environment furnace for 4 h. The samples were then milled for 2 h by high-energy ball milling. X-ray diffraction (XRD) pattern indicated that in this stage the samples are single phase. The microstructure investigation was carried out by a scanning electron microscope with maximum magnification of 30,000. The average grain size for different samples was estimated by XRD technique and transmission electron microscopy. Magnetic behavior of the samples at room temperature was studied using an alternating gradient force magnetometry. The Néel temperature of the powders was measured by a Faraday balance. Based on magnetic studies, increase in bismuth content leads to a decrease in the saturation magnetization, coercive field and Néel temperature. This can be attributed to the substitution of Bi³⁺ ion in the ferrite system as a nonmagnetic cation.     

On-line extraction and determination of uranium in aqueous samples using multi-walled carbon nanotubes-coated cellulose acetate membrane

In this work, multi-walled carbon nanotubes (MWCNTs)-coated cellulose acetate membrane was used for on-line extraction and pre-concentration of uranium from aqueous samples prior to inductively coupled plasma optical emission spectrometry (ICP-OES) determination. Sample solutions containing the U(VI)-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (Br-PADAP) complex were passed through the membrane. The adsorbed analyte was subsequently eluted from the membrane with acid, which was directly introduced into the ICP-OES nebuliser. The main variables affecting the pre-concentration and determination steps of uranium were studied and optimised. Under the optimised conditions, the enrichment factor of 150 and the detection limit of 0.16 μg L^–1 were obtained. This method was successfully used for determination of uranium in environmental water samples.     

Synthesis and characterization of new fluorinated photoactive polyamides based on xanthene pendant: Evaluation of antibacterial and heavy metal ions removal behavior

A series of novel organosoluble polyamides (PAs) bearing different functional groups such as flexible ether, substituted imidazole, and xanthene rings and electron-withdrawing CF₃ groups were synthesized from diamines and various dicarboxylic acids. The structures of diamines and PAs were fully characterized by elemental analysis, Fourier transform infrared spectroscopy, and proton nuclear magnetic resonance spectroscopy. The PAs showed good solubility in aprotic and polar organic solvents, with high thermal stability exhibiting the glass transition temperatures (T_gs) and 10% weight loss temperatures (T₁₀%) in the range of 184–277°C and 410–480°C in N₂ atmosphere, respectively. These polymers showed fluorescence emission upon irradiation with UV light. Diamine compounds and two of synthesized polymers were also screened for antibacterial activity against gram-positive and gram-negative bacteria, and the obtained results for all four combinations showed good inhibition. Extraction capability for heavy metal ions such as Cr³⁺, Pb²⁺, Hg²⁺, Cd²⁺, and Co²⁺ from aqueous solutions was also tested at 25°C and pH 7–8.     

Study of the surface properties and surface concentration of ionic liquid–alcohol mixtures

Surface properties for three binary mixtures containing a 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]) and a long-chain alcohol (1-butanol, 1-pentanol and 1-hexanol) were determined by surface tension data at the following temperatures: (298.15, 308.15, 318.15, 328.15 and 338.15) K. The surface tension data over the entire mole fraction range are correlated by the Fu et al.(FLW) and Myers-Scott (MS) models. There is good agreement between the experimental data and the results of correlations for 15 binary systems (the three systems at five temperatures) with an average relative error below 1.5%. In addition, the UNIFAC group contribution method is applied for calculation of activity coefficients of components in solution. Moreover, the relative adsorptions of alcohol at the air/liquid interface are determined using Gibbs adsorption isotherm. The obtained results show that the values of adsorption for mixtures of alcohols/[BMIM][SCN] increase with increasing the alkyl chain length of alcohol and decreasing temperature.     

An aptasensor for tetracycline using a glassy carbon modified with nanosheets of graphene oxide

Microchimica Acta - The authors describe an aptasensor for tetracycline (TET) based on the use of a glassy carbon electrode (GCE) modified with graphene oxide nanosheets. The latter were placed on...     

A numerical study on the effect of static magnetic field on the hemodynamics of magnetic fluid in biological porous media

Journal of Thermal Analysis and Calorimetry - High interstitial fluid pressure in the tumor is among the most important barriers to drug delivery. The use of the static magnetic field is one of the...     

Numerical prediction of humidification process in planar porous membrane humidifier of a PEM fuel cell system to evaluate the effects of operating and geometrical parameters

In present study, a numerical model is employed to investigate the effects of different operating parameters and channel geometry on the performance of membrane humidifier. Simulations are performed by a commercial CFD code and based on user defined functions. Three-dimensional counter-flow humidifier model for a gas-to-gas case is considered. Results show that an increase in porosity or permeability leads to better humidification. Moreover, increase in inlet temperature of dry and wet channels as well as inlet mass flowrate of water vapor would enhance humidifying process. On the other hand, by reduction in inlet mass flowrate of gas channel and thickness of the porous medium in membrane, better humidifier performance would be achieved. To investigate the geometric parameters, three different channel types including stepped, sinusoidal and zigzag are considered. It is found that stepped geometry has the best performance in humidifying.