Yomen Atassi

Preparation of bentonite-g-poly(acrylate-co-acrylamide) superabsorbent polymer composite for agricultural applications: Optimization and characterization

Based on water absorbency, the Taguchi method was employed for the optimization of the synthetic parameters of a superabsorbent polymer composite production. Bentonite has been grafted to poly(acrylate-co-acrylamide) under microwave irradiation using methylene-bis-acrylamide as a cross-linker and potassium persulfate as an initiator. The hydrogel structure was confirmed using FTIR spectroscopy and the exfoliation of the bentonite was investigated by X-ray diffractometry. The morphology of the sample was examined by scanning electron microscopy. The relative thermal stability of the composite in comparison with the corresponding copolymer was proved via thermogravimetric analysis. The effect of various salt media and solutions with different pHs on the swelling of the superabsorbent composite was also studied. The role of the prepared composite as a soil conditioner has been tested.

LOW SINTERING TEMPERATURE OF MG-CU-ZN FERRITE PREPARED BY THE CITRATE PRECURSOR METHOD

Mg-Cu-Zn ferrite was prepared through a wet synthetic method by a self-combustion reaction directly from a citrate precursor. The as-synthesized powders were sintered at 750 °C for only 2 h. XRD patterns and FTIR spectra confirm the formation of single phase Mg-Cu-Zn ferrite after combustion. To the best of our knowledge, this is the first time that Mg-Cu-Zn ferrite is sintered at such a low temperature. The sintering process increased the crystallinity of the solid and the domain sizes.

Synthesis of Calcium Titanate Powder with Hollow Square Based Prism Morphology via One-Step Surfactant Free Hydrothermal Method: Temperature Effect and Optical Properties

ABSTRACT In this work, we report a morphologically controlled growth of hollow micrometer-sized prism of perovskite calcium titanate via one-step surfactant free hydrothermal method. Highly concentrated potassium hydroxide is used as a mineralizer in this procedure. Single phase of CaTiO3 appears after treatment for 180 min during the one-step hydrothermal conditions. The reaction yield is 97% and no impurity is observed in the final product. The uniformly dispersed particles obtained from the hydrothermal method have hollow micro square based prism morphology with an average size of about 2 μm in length and 200 nm in diameter. The results indicate that the hydrothermal method is a suitable procedure to prepare CaTiO3 microparticle with a desired morphology for industrial applications. The optical properties of the prepared samples are also investigated. GRAPHICAL ABSTRACT

On calorimetry by optical beam deflection method

In this work, we analyze different factors that may affect heat measurements, in a device, based on the optical beam deflection method (OBD). We demonstrate that it is possible to improve the heat limit of detection (HLOD) of the device by increasing its sensitivity using a proper cell or a proper monitoring phase. On the other hand, we prove experimentally that the gradient of the refraction index is almost vertical, so it is possible to apply a theoretical model based on one-dimensional heat propagation to predict the temporal behavior and the magnitude of the deflection beam.