Evaluation of an ultrasonic-assisted mechanical stirring technique for the synthesis of an efficient nano-photocatalyst

Photocatalysis has emerged as an efficient technique for the removal of contaminants from wastewater. In this work, conventional mechanical stirring was compared with ultrasonic-assisted mechanical stirring for the synthesis of an efficient nano-photocatalyst (AlO)(ZnO)FeO. The photocatalytic activity of (AlO)(ZnO)FeO synthesized by both techniques was compared for the degradation of methyl orange dye (MO) under visible light irradiation. Important process parameters were optimized during the study and the results indicated that the photocatalyst synthesized by ultrasonic-assisted mechanical stirring was more efficient with 93.5% photocatalytic activity for the degradation of MO dye than that synthesized by using a simple mechanical stirring technique which resulted in photocatalytic activity of 83.7%. (AlO)(ZnO)FeO nano-photocatalysts synthesized by both methods were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, dynamic light scattering and BET surface area analysis. The results indicated that the particle size of the (AlO)(ZnO)FeO catalyst synthesized by ultrasonic-assisted mechanical stirring was significantly smaller and the surface area larger than the particles prepared by the conventional mechanical stirring method. A cyclic study evaluated the reusability of the photocatalyst and found minimal loss in degradation efficiency after seven cycles. The optimal photocatalyst produced in this study can degrade higher concentrations of MO with a higher efficiency using a lower or similar catalyst dose compared to other materials published in the literature

Replacement materials for facial reconstruction at the soft tissue–bone interface

The challenges faced by any tissue repair and regeneration process resulting from either trauma or disease are many and complex. Although it is of course impossible to identify any one anatomical region as being the most demanding in this respect, the craniofacial region surely qualifies. The judicious choice of available, well-defined, and tested repair materials to be used in the reconstruction process by the multidisciplinary team of reconstructive surgeons is critical. This chapter addresses one aspect of facial reconstruction that has been less well addressed in the literature, namely the materials used to repair and regenerate soft tissue both in terms of fillers and in terms of materials used at the hard-soft tissue interface

A novel strategy for preparing mechanically robust ionically cross-linked alginate hydrogels

The properties of alginate films modified using two cross-linker ions (Ca(2+) and Ba(2+)), comparing two separate cross-linking techniques (the traditional immersion (IM) method and a new strategy in a pressure-assisted diffusion (PD) method), are evaluated. This was achieved through measuring metal ion content, water uptake and film stability in an ionic solution ([Ca(2+)] = 2 mM). Characterization of the internal structure and mechanical properties of hydrated films were established by cryogenic scanning electron microscopy and tensile testing, respectively. It was found that gels formed by the PD technique possessed greater stability and did not exhibit any delamination after 21 day immersion as compared to gels formed by the IM technique. The Ba(2+) cross-linked gels possessed significantly higher cross-linking density as reflected in lower water content, a more dense internal structure and higher Young's modulus compared to Ca(2+) cross-linked gels. For the Ca(2+) cross-linked gels, a large improvement in the mechanical properties was observed in gels produced by the PD technique and this was attributed to thicker pore walls observed within the hydrogel structure. In contrast, for the Ba(2+) cross-linked gels, the PD technique resulted in gels that had lower tensile strength and strain energy density and this was attributed to phase separation and larger macropores in this gel