Study of Proton Leakage at Interface of Anion-Exchange Membrane in Solutions of Acids,Salts, and Solvents Using Current/Voltage Characteristics

Water dissociation and proton leakage using the anionic exchange membrane (AMH) are studied by means of current/voltage characteristics and confirmed by simulation of transport number using Hittorf's method. The acids used are HCl, HNO₃, and H₂SO₄ and the salts are NaCl, ZnCl₂, and NaNO₃. Concentration polarization of such membrane is accompanied by a change in the electrolyte concentration/solution interface due hydrolysis reactions. The results show that when the concentration of the electrolyte increases, the limiting current density increases linearly and the transmembrane resistance decreases systematically. The thickness of the diffusion layer is always higher in presence of acid than salt, making in evidence the proton leakage through the membrane. Besides, when the membrane is selectively permeable to chloride anion in the case of ZnCl₂, the thickness of the double layer is rather bigger and far exceeds that of the membrane. The voltamperometry method seems reliable and offers some advantages over that of Hittorf because it shows the effects of some parameters on the value of limiting current: concentration, counter-ion types (Cl^?, NO₃^? SO₄^2?), and the gradient of concentration in the anode and cathode compartments. It can, therefore, allow to optimize the value of the current which should be used in electrodialysis in any form and without a great consumption of energy. Moreover, the simulation carried out for transport number of proton, shows its sensitivity toward the variation in concentration in the receiving compartment. In effect, a small decrease in concentration implies an enormous decrease in its value.     

An Efficient Mobile Data Gathering Method with Tree Clustering Algorithm in Wireless Sensor Networks Balanced and Unbalanced Topologies

Wireless Personal Communications - Electroencephalography (EEG) is a technique of Electrophysiology used in a wide variety of scientific studies and applications. Inadequately, many commercial...     

Studies of non-vacuum processing of Cu-chalcogenide thin films

Cu-chalcogenide thin films were prepared using a two stage method: one step electrodeposition of CuISe and CIGSe, and the sulfurisation of CISe to prepare CISSe thin films. The films were deposited on different substrates: Mo and ITO coated glass. The optimum potentials for electrodeposition of CISe and CIGSe films were respectively selected in the range -400 to -550 mV and -650 to -700 mV (vs. SCE). The electrodeposited layers were firmly adhesive. The well known chalcopyrite structure appears after annealing at 400 degrees C under Argon for CISe. The band gap value deduced from the optical measurements is close to 1 eV. To increase this value, addition of gallium in the aqueous electrolytic solution was performed. A band gap value as high as 1.26 eV was recorded on the obtained CIGSe films. Sulfurisation of CISe layers under 5% H2S/Ar atmosphere lead to a shift of the position of the principal XRD peaks indicating the substitution of selenium atoms by sulfur atoms and thus the formation of the quaternary CISSe. Optical measurements performed on this quaternary compound show that our films exhibit a band gap value scaling from 1 eV to 1.4 eV depending on the amount of sulphur incorporated into the layers during the heat treatments.     

Fuzzy Tree Clustering Algorithm with Mobile Data Collectors in Wireless Sensor Networks

In recent years, the need to deploy Wireless Sensor Networks increases in different applications. Several studies have been proposed to demonstrate the importance to use Mobile Data Collectors (MDC) in Wireless sensor Networks. The main goal of this paper is to reduce the energy consumption of sensor nodes and to extend the network lifetime. In this paper, we propose to construct a Minimum Spanning tree, we design a fuzzy Cluster Head election system to elect the best sensor nodes as Cluster Heads, considering two input parameters, namely the weight of Sensor Nodes (WoSN) and the State of Sensor Node Locations (SoSNLoc). To extend the network lifetime, a subset of MDCs travels the area to gather the sensed data from nodes instead of sending them directly to the Base Station (BS) in a single hop or multi-hop manner. The BS is located at the center of the area which will be divided into sub-regions, one for each MDC. According to their positions, each CH will belong to a specific region, and then will be visited by the corresponding MDC. Simulation results show the effectiveness of our proposed algorithm in terms of energy consumption and network lifetime in comparison with other ones.

     

Properties of concrete reinforced with different kinds of industrial waste fibre materials

Nowadays, the use of different types of sub-products in cement-based materials has become a common practice in concrete industry. This paper discusses the feasibility of adding metallic and polypropylene by-product fibres as reinforcement of normal concrete. The effects of the incorporation of various types of waste metallic fibres (WMF) and polypropylene fibres (WPF) on the mechanical properties of fibre-reinforced concrete were experimentally investigated. A normal concrete with a compressive strength of 30 MPa was used as a control mixture. The influence of type, volume and length of WF on the compressive and flexural strengths, and toughness of fibres reinforced concrete (FRC) is evaluated. The results obtained have shown that the WPF decreases the compressive strength of WFRC, especially when using long fibres with high volume fraction. A slight decrease of the compressive strength was also observed with the composites containing more than 2% of the WMF. However, adding the WPF and the hybrid fibres increases the flexural strength of the WFRC. It has been observed that the composites reinforced with the WPF is more advantageous in terms of post-cracking behaviour and load-carrying capacity as compared to the composites reinforced with the WMF even in some cases, the WPF performs better than the multimodal composites. The results have shown that generally, ductility, toughness, and especially the post-cracking behaviour of the WFRC are significantly improved when using the multimodal composites compared to composites reinforced with the mono-fibres system. Results regarding orientation and distribution of fibres into the cement matrix, and porosity and their effect on the WFRC performance were also discussed.     

Nutritional characteristics,biochemical composition and antioxidant activities of Moroccan Oat varieties

Oat has been recognized as a healthy food for a long time. In this study, physicochemical analysis including, moisture, pH, ash, fibres, proteins, starch, carbohydrates, some minerals, sugars, fatty acids, sterols, total phenolic, and flavonoid contents of four Moroccan Oat varieties (Amlal, Tissir, Zahri and Ghali) were investigated. Additionally, starch morphology has been described according to scanning electron microscopy, and viscosity as measured on a rotary rheometer, increased with stabilization time. Furthermore, Oat extracts were analyzed with regard to their antioxidant activities using DPPH radicals’ cation, Trolox equivalent antioxidant capacity and ferric reducing/antioxidant power. Results from this investigation demonstrated that Moroccan Oat varieties constitute an interesting supplement of natural antioxidants, especially phenolic compounds. Moreover, potassium was the main mineral in Oat seeds (1628.17–2541.52 mg/Kg); also, the oleic, linoleic, and palmitic acids were the dominant fatty acids. While the major sterols were, β-sitosterol, Δ-5-avenasterol and campesterol. Finally, sugar analysis by HPLC-RI indicate that sucrose content was higher than glucose and fructose respectively, and that Ghali and Amlal varieties exhibit an important total sugars levels. Those results highlight the possible contributions of Oat seeds to nutritional therapy.     

The sorption of lead, cadmium, copper and zinc ions from aqueous solutions on a raw diatomite from Algeria

The adsorption of Cu(2+), Zn(2+), Cd(2+) and Pb(2+) ions from aqueous solution by Algerian raw diatomite was studied. The influences of different sorption parameters such as contact pH solution, contact time and initial metal ions concentration were studied to optimize the reaction conditions. The metals ions adsorption was strictly pH dependent. The maximum adsorption capacities towards Cu(2+), Zn(2+), Cd(2+) and Pb(2+) were 0.319, 0.311, 0.18 and 0.096 mmol g(-1), respectively. The kinetic data were modelled using the pseudo-first-order and pseudo-second-order kinetic equations. Among the kinetic models studied, the pseudo-second-order equation was the best applicable model to describe the sorption process. Equilibrium isotherm data were analysed using the Langmuir and the Freundlich isotherms; the results showed that the adsorption equilibrium was well described by both model isotherms. The negative value of free energy change ΔG indicates feasible and spontaneous adsorption of four metal ions on raw diatomite. According to these results, the high exchange capacities of different metal ions at high and low concentration levels, and given the low cost of the investigated adsorbent in this work, Algerian diatomite was considered to be an excellent adsorbent.     

Influence of a combination of expansive and shrinkage-reducing admixture on autogenous deformation and self-stress of silica fume high-performance concrete

High-performance concrete (HPC) is characterized by its low water-to-cementitious materials (w/cm) and improved properties but also it exhibits high internal capillary tensile stress because the development of autogenous shrinkage which could result in early-age cracking risk and premature deterioration. Since the use of HPC in structural elements has gained wide acceptance in the last decades, the large magnitude of early-age autogenous strains and stresses has to be mitigated to enhance the durability of concrete structure. In this paper, internal stress development induced during the development of autogenous shrinkage strains, especially at early-age was investigated on three different types of HPC cured with a combination of two shrinkage-compensating admixtures. Binary HPC made with blended cement containing 10% of silica fume (SF) has been used with three different low (w/c + sf) of 0.15, 0.23, and 0.30. Shrinkage-reducing agent (SRA) and an expansive additive (EXA) were combined and added to the HPC mixtures to minimize autogenous shrinkage magnitude.The results indicate that the greater the autogenous shrinkage developed, the higher the induced internal tensile stress. It has been found that for the reference mixes, more than 90% of the ultimate magnitude of both autogenous shrinkage and self-tensile stress was developed during the first 24 h. However, the addition of a combination of SRA and EXA has resulted in a significant reduction and a gradual development of both autogenous shrinkage and self-tensile stress as compared to the rapid development and large magnitude in the reference concretes. Moreover, a high dimensional stability was obtained for the 0.30 and 0.23 HPC mixtures containing the combination of expansive and shrinkage-reducing admixtures. On the other hand, a slight decrease of the compressive, of the splitting tensile strengths and the modulus of elasticity was observed.