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In this study, LaFeO3 perovskite is synthesized by the flash method, and then a simple method is developed for growing SiO2 on its surface to construct a core/shell nanocomposite. The thickness of the SiO2 shell is controlled by varying the amount of tetra-ethyl orthosilicate (TEOS). Two LaFeO3@SiO2 samples with varying SiO2 thicknesses were synthesized. Herein, the lattice parameters, morphology, magnetic, and adsorption properties of the investigated core/shell nanocomposites are tuned by changing the content of SiO2. Results confirm that when the content of SiO2 increased, the prepared LaFeO3@SiO2 core/shell nanocomposite showed good adsorption performance, and the removal efficiency enhanced from 50 to 60% for LaFeO3 and LaFeO3@SiO2, respectively. It is thought that the enhancement of the adsorption performance is related to the high porosity and amorphous nature of SiO2. [ABSTRACT FROM AUTHOR]

M–Co Fe 2 O 4 (where M=Cu and Zn) nanoferrites were successfully prepared using the citrate auto-combustion technique. The main idea was drawn through a complete study of the structural, morphological, thermal, magnetic, and electrical properties. The obtain findings were explained in the light of incorporation both Cu 2 + and Zn 2 + ions in the Co Fe 2 O 4 crystal. All the investigated samples were found to belong to space group (Fd-3m) and space group number (227). The crystallite size of the Co Fe 2 O 4 , Cu–Co Fe 2 O 4 , and Zn–Co Fe 2 O 4 nanoparticles was found to be 8, 15, and 14, respectively. While, the lattice constants were 8.4 nm, 8.39 nm, and 8.42 nm, respectively. The doping exhibits enhancement of the elastic properties. Cu–Co Fe 2 O 4 shows young' modulus at 278.97 GPa, while the shear modulus was 185.98 GPa, as highest obtained values compared to virgin and other doping samples. The highest saturation magnetization was observed for virgin sample, Co Fe 2 O 4 , (56.1 emu/g) compared to it being 46.9 and 45 emu/g for Cu–Co Fe 2 O 4 and Zn–Co Fe 2 O 4 , respectively. The highest magnetic susceptibility (0.639) was obtained for Zn–Co Fe 2 O 4 . The thermal conductivity, thermal diffusivity, and specific heat of the prepared samples were investigated by the hot disk technique at room temperature. The results have shown an enhancement in the thermal properties of Co Fe 2 O 4 -doped Zn and Cu rather than virgin Co Fe 2 O 4 , predicting required thermal stability in the working devices. The Cu–Co Fe 2 O 4 sample exhibits the highest value of thermal conductivity (0.95 W/m k), thermal diffusivity (0.75 m m 2 /s), and specific heat (0.85 Mj/ m 3 k) compared to (0.6 and 0.82 W/m k), (0.52 and 0.6 m m 2 /s), and (0.62 and 0.72 Mj/ m 3 k) for Co Fe 2 O 4 and Zn–Co Fe 2 O 4 , respectively. The electrical conductivity and permittivity of all ferrite samples were enhanced by augmenting the temperature. The highest values were achieved for Co Fe 2 O 4 sample. The present Co Fe 2 O 4 -doped Cu 2 + and Zn 2 + ions offer a decent contender material with appealing characteristics suitable for different electronic applications. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) polymer is considered as an encouraging piezoelectric material whose optical properties need to be enhanced. Zinc ferrite is an excellent photoelectric material, in the present work it was doped separately by (cobalt and copper) ferrite. Co-ZnFe2O4 and Cu-ZnFe2O4 nanoparticles were synthesized using auto-combustion method and characterized using XRD, FTIR, FESEM and HRTEM. The crystallite size was (28.8, 35.8, 22 and 31) nm for the Co-ZnFe2O4 and Cu-ZnFe2O4 nanoparticles, while the estimated particle size from HRTEM were 55 nm for the Co-ZnFe2O4 nanoparticles and 75 nm for the Cu-ZnFe2O4. The obtained samples used as PVDF fillers, aiming to improve its optical properties. The optical properties as well as, the piezoelectric response of the prepared PVDF/(Co-ZnFe2O4 and Cu-ZnFe2O4) nanocomposites were investigated. The maximum value for refractive index was related to PVDF/Co-ZnFe2O4 nanocomposite. While, Cu-ZnFe2O4 nanoparticles have limited improvement of the PVDF optical properties. Co-ZnFe2O4 nanoparticles increases the PVDF optical conductivity σopt. four times its original value as well as the dielectric values was increased from 0.05 for neat PVDF to 2. The piezoelectric response of the PVDF polymer is clearly increased by the addition of both Co-ZnFe2O4 and Cu-ZnFe2O4 nanoparticles. [ABSTRACT FROM AUTHOR]

In this study, ferrites nanoparticles of formula MFe2 O4 (M = Co, Zn, and 50% Co/50% Zn) were synthesized and characterized by X-ray diffraction, Fourier transforms infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and the N2 adsorption–desorption technique. The magnetic properties were studied using a vibration sample magnetometer, and the magnetic susceptibility was measured as a function of temperature. Among the specimens evaluated, CoFe2 O4 has the largest saturation magnetization (66.380 emu/g), and ZnFe2 O4 exhibits the largest surface area (120.1 m² /g). The prepared nanoparticles were investigated as adsorbents for the removal of methylene blue (MB) from an aqueous solution at different contact times, pH, and initial concentrations. The influence of the adsorption conditions was examined, finding that the adsorption process is favored in alkali conditions and high MB concentration. The Langmuir and Freundlich models fit the adsorption data of CoFe2 O4 and the composite, whereas only the Freundlich model fits the experimental results of ZnFe2 O4 . The adsorption kinetics of MB adsorption onto MFe2 O4 is better described by pseudo-first-order and pseudo-second-order models than by an intraparticle diffusion model. [ABSTRACT FROM AUTHOR]

This paper describes the development of a general probabilistic model of a Diesel-wind energy conversion system (DWECS) composed of several Diesel units, several wind turbines (wind farm), and battery storage feeding a load. The model allows the simulation of a Diesel system with a wind farm of different wind turbine types considering system stability, and outages due to hardware failure and primary energy fluctuations. It is based on a modification of the convolution method, which considers a given penetration level selected by the utility for stability consideration. The production costs of the Diesel units are then deduced from the expected energy not supplied (EENS) using a unit de-convolution in reverse economic order. A methodology is also presented to determine the size of the battery storage based on the excess wind energy available during operation, or that disconnected for stability consideration, while accounting for the charging/discharging cycles. Index Terms--Diesel generation, production costing, reliability evaluation, renewable energy, storage sizing.