Soil Desalination via Poly(vinyl alcohol) Borate Hydrogel

Theoretical Foundations of Chemical Engineering - Saline and sodic soil sample was collected from salty beach. Polyvinyl alcohol borate hydrogel due to its cation attracting ability was utilized as...     

A review of chemical absorption of carbon dioxide for biogas upgrading

Significant attention has been given to biogas production, purification and upgrading as a renewable and clean fuel supplement. Biogas is a product of an anaerobic digestion process comprising methane, carbon dioxide, and trace amounts of other gases. Biogas purification removes trace gases in biogas for safe utilisation. Biogas upgrading produces methane-rich biogas by removing bulk carbon dioxide from the gas mixture. Several carbon dioxide removal techniques can be applied for biogas upgrading. However, chemical absorption of carbon dioxide for biogas upgrading is of special significance due to its operation at ambient or near ambient temperature and pressure, thus reducing energy consumption. This paper reviews the chemical absorption of carbon dioxide using amine scrubbing, caustic solvent scrubbing, and amino acid salt solution scrubbing. Each of these tech-niques for biogas upgrading is discussed. The paper concludes that an optimised implementation of the chemical absorption techniques for biogas upgrading requires further research.     

Hydrothermal synthesis,sintering and characterization of nano La-manganite perovskite doped with Ca or Sr

Two lanthanum manganite perovskite-nanostructures, namely; La_xCa_(1-x)MnO₃ and La_xSr_(1-x)MnO₃ (x?=?0.1, 0.3, 0.5 and 1.0), were synthesized by hydrothermal method. To follow up the composition of formed phases, the synthesized powders were calcined at different temperatures. The obtained materials were investigated by X-ray diffraction (XRD) and transmission electron microscope (TEM). Moreover, the calcined powders were pressed at 100?MPa and sintered at variable temperatures; i.e. 1250, 1300, 1350 and 1450?°C. The phase composition and microstructural characteristics of sintered pervoskites were examined by XRD and scanning electron microscope (SEM). Furthermore, physical (bulk density and apparent porosity), electrical resistivity and magnetic properties were also determined. The results revealed that La_xCa_(1-x)MnO₃ and La_xSr_(1-x)MnO₃ nanostructures were successfully prepared by hydrothermal method. The physical properties of sintered pervoskites were strongly depended on dopant type and concentration. The maximum sintering temperature for La_xCa_(1-x)MnO₃ was 1400?°C while for La_xSr_(1-x)MnO₃ was 1450?°C, after which the materials have been fused. Materials doped with Ca or Sr exhibited lower resistivity. On the other side, the magnetic properties have been also improved after addition of Ca or Sr. This has been discussed based on the double exchange mechanism. La_xSr_1-xMnO₃ exhibited better magnetic properties than La_xCa_1-xMnO₃ and LaMnO₃. La_0.5Ca_0.5MnO₃ and La_0.5Sr_0.5MnO₃ exhibited the highest magnetization among the other pervoskites.     

Flexible polybenzoxazine thermosets containing pendent aliphatic chains

The rich chemistry of polybenzoxazines allows a wide range of molecular structure design by using appropriate starting materials. A new class of polybenzoxazines has been developed from benzoxazine monomers containing pendent long aliphatic chains. The monomers have been synthesized by the reaction of phenol or bisphenol A with two different long‐chain aliphatic amines. The chemical structure of the monomers was confirmed by ¹H nuclear magnetic resonance and Fourier transform infrared spectroscopy. The polymerization behavior of the monomers studied by differential scanning calorimetry shows exothermic peaks due to the ring‐opening polymerization of benzoxazine monomers centered at 247–255 °C. Dynamic mechanical analysis indicated that the glass transition temperatures T_g were in the range 81–92 °C. The thermal stability of the polymers was also examined by thermogravimetric analysis, demonstrating that the weight loss temperatures decreased in comparison with that of traditional polybenzoxazine. Copyright © 2011 Society of Chemical Industry     

Dual-Path Part-Level Method for Visible–Infrared Person Re-identification

Neural Processing Letters - Visible–infrared cross-modality person re-identification is a realistic problem of person re-identification. Under poor illumination scenario, general methods of...     

A boundary-based approach to shape orientability using particle swarm optimization

In this paper, a new method to compute the orientability of different shapes is defined. The proposed technique is a boundary-geometry-based method that tends to take advantage of the simplicity of finding the orientability of an ellipse to obtain the orientability of any arbitrary shape. This is accomplished by finding the best-fitting ellipse of the shape. Initially, Canny edge detector is applied to obtain the edge map of the image. Convex hull points are identified and used to represent the shape. Three different approaches are presented to find the best-fitting ellipse. The three approaches use different definitions to the notion of the best-fitting ellipse of the shape. The first approach tries to find the minimum area ellipse that completely encloses the shape. While the second approach hardens the search constraints by searching for the minimum area ellipse whose center coincides with the center of the shape and completely encloses it. Alternatively, the third approach aims to find the maximum area ellipse that could be completely enclosed inside the shape and has the same center as of the shape. The three approaches utilize the particle swarm optimization technique with penalty function to solve the constrained optimization problem by defining the cost function as a multi-level function.     

Water resources and freshwater ecosystems in Sudan

Sudan is a large country with varying standards of living, culture and climate. When this is superimposed on the multi-sectoral nature of water, coordination of activities in water resources planning, management and development becomes essential. The spirit of cooperation and close cooperation with countries sharing the same water resources should continue, preferably through an institutional cooperative framework for each shared basin. The guiding sprit should be equitable, legitimated, integrated, sustainable and environmentally sound utilisation of the common water resources, without significant harm from one country to another. Some of the issues and problems faced are referred in this article. Sudan has recently taken some major steps to organise the water sector. The article also shows some of the joint efforts to establish and advance cooperation with the Nile basin countries for integrated development of the shared watercourse. It concluded with a future policy look to address the emerging issues. A water policy is bound to be dynamic as it addressed issues with many variables. It is expected that, as time goes on, some new issues will surface while earlier issues will fade out. When this happens, another review of the water sector policy would be appropriate.