Vol 52, No 6 (2016)

We developed technological procedures for preparation of filiform nanostructures (FNSs) on the basis of stretching microwires with magnetic material cores. It is shown that disruptions of the microwire core occur for these materials during technological process of stretching due to relatively high melting temperature of magnetic alloys. As a result, FNSs with elongated magnetic inclusions are produced. An installation for the production of FNSs as well as an experimental complex for measuring magnetic properties of the produced magnetic FNSs is described in this paper. The morphology of the produced FNSs from microwires with magnetic bistability is investigated by means of scanning electron microscopy, while magnetic properties, such as magnetic response with remagnetizing pulses, hysteresis loop, and coercive force, are investigated on the developed experimental complex. The magnetic interaction during remagnetizing processes of several microwires with different coercive forces assembled in a bunch, as well as the reaction of a bunch assembled from a big number of bistable mirowires of two types with different coercive forces (soft magnetic and hard magnetic cores) upon increasing external magnetic field are also investigated. Some potential applications of the produced magnetic structures are suggested.

This study focuses on analysing the durability of adhesive bonds formed in samples of Aluminium 6063, Titanium Nitride deposited Al 6063 and Anodized Al 6063 using epoxy adhesive Weicon A. Two types of studies are performed, first, samples of Aluminium 6063, Titanium Nitride deposited Al 6063 and Anodized Al 6063, are bonded by an epoxy adhesive Weicon A. Second, the samples are bonded by the adhesive with reinforcement of Ca₂SiO₄ nanoparticles in different proportions. The samples are examined using the scanning electron microscopy to study the morphology of the coating. A lap shear test is performed to determine the strength of the adhesive after the specimens were subjected to harsh chemical environments. A thermogravimetric analysis is performed on the adhesive to understand the effect of nanoparticles in the thermal stability in the Weicon A. It is understood from the tests that the titanium nitride coated Al 6063 samples bonded with Weicon A exhibited greater bond strength and also retained the strength when exposed to harsh environments. The inclusion of calcium silicate nano-particles showcased a considerable reduction in the bond strength. The thermal stability of Weicon A seems to be unaffected by the inclusion of calcium silicate nanoparticles.

In order to study the effect of the preparation method on structural and textural properties of pillared clays, alumina-pillared bentonite clay (Al-PILC) was prepared using two different methods: the conventional and ultrasonic one, during the aging process for the pillaring solution and during the aging in the intercalation stage. Compared with the conventional treatment, the use of an ultrasonication method considerably reduces the modification time (from 24 h to 20 min) for the synthesis of the pillared clay. The characterization of solids by the elemental chemical analysis, X-ray diffraction (XRD), cation exchange capacity (CEC), N₂ adsorption/desorption isotherms, scanning electron microscopy (SEM) and temperature-programmed reduction (H₂-TPR) techniques showed that the use of ultrasound brings not only very similar results to those obtained with the classical method, but also present a better structural and textural properties than the clay pillared with the conventional treatment.

The aim of this review is to discuss the effect of different pretreatments on the physical and chemical properties of Indium Tin Oxide (ITO) thin films, as well as device performance towards sensor applications. The emphasis is on the surface science studies of ITO thin films before and after treatment in order to provide connecting points between surface properties with a broader field of materials science of ITO. The morphology of a monolayer deposited on ITO directly affects the surface properties of prepared ITO films. Thus, it is a topic of interest to study the influence pretreatment on the surface morphology of ITO films on device fabrication and applications as a device platform.

In this paper, adsorptive performance of natural clay has been investigated as a potential reactive dye adsorbent, on the basis its promising physical-chemical and morphological properties which were compared to several previous works. Sample used in this work, collected from Grombalia (North-East of Tunisia), has been characterized at the first time. Following its physicochemical study, this sample has been employed and tested as an ion exchange medium, for an anionic toxic textile dye removal from textile effluent and watercourse. Physicochemical experiences confirm that the used clay mineral was a clay of bentonite type having the following structure formula Ca_0.014Na_0.404K_0.16(Si_7.65Al_0.35)(Al_2.910Fe_0.762Mg_0.376)O₂₂. Dye removal from aqueous solution onto raw (GRb) and purified (GRp) bentonite was investigated, using a batch adsorption technique, as a function of various parameters such as initial dye concentration, contact time, temperature and pH medium. Results prove that the amount of dye removed by the raw and the purified bentonite was found to be around 142 and 294 mg/g respectively. According to previous works this quantity of dye removed from aqueous solution (294 mg/g) reach the anionic exchange capacity of bentonitic sample. A contact time (clay/dye solution) of 20 to 30 min was sufficient to reach adsorption equilibrium. Adsorption rate was fast, more than half of the adsorbed dye was removed from the aqueous solution (C = 10^–4 M). The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms. Experimental data fit well with Freundlich model (the correlation coefficients, R², was found to be equal to 0.98).

Porous electrodes of an activated carbon material have been modified by bivariant mechanical tuning (optimization of electrode density and thickness). Features of this method have been described in detail; the electrochemical behavior of porous carbon electrodes of varying density (0.35, 0.55, and 0.75 g/cm³) in a wide thickness range (60–1400 μm) has been studied. In addition, the possibility of using the modified electrodes in high-power symmetric and high-energy asymmetric supercapacitors has been analyzed; an additional criterion for the selection of the electrodes for the supercapacitors has been proposed.