This review article reports the most significant advances made in H 2 production via water-splitting and the challenges that need to be addressed over the coming years to verify the feasibility of H 2 production by both inorganic semiconductors and living microorganisms as a competitive process in the hydrogen economy.

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Paraffin and polyethylene waxes were found to be efficient as controlled delivery systems for six different commercial-grade fertilizers. These fertilizers are monoammonium phosphate, diammonium phosphate, NP, NPK-4, and NPK-14 grades, and granular triple superphosphate fertilizers. Dissolution tests were performed for matrix-type formulations in order to determine the influence of waxes on the fertilizers release rate. Three different diffusion release formulas were tested for describing the release rate of the different fertilizers. The release times were at least doubled for all of the fertilizers while using either paraffin wax or polyethylene wax. The polyethylene wax gives longer release times than the paraffin wax.

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High density polyethylene (HDPE) with micro calcium carbonate (CaCO 3 ) masterbatch was pelletized by using a twin screw extruder and different ASTM specimens were molded by an injection molding machine. The morphology of the composites was characterized by scanning electron microscopy (SEM) and Image Analysis software. The dispersion and interfacial interaction between CaCO 3 and the polymer matrix were also investigated by SEM. The thermal properties of HDPE and its composites were investigated by differential scanning calorimetry (DSC). The crystallization process of the composites samples was found to be slightly different than that of the neat HDPE. Otherwise, the presence of CaCO 3 did not have a considerable effect on the melting behavior of the composites. Thermogravimetric analysis (TGA) revealed that the composites had better thermal stability than the neat HDPE resin as indicated by a higher temperature of 50% weight loss (T 50% ) for the composites as compared to that of the neat resin. The viscoelastic properties of the composites and HDPE were also investigated via torsional and rotational techniques. The presence of CaCO 3 increased the shear modulus at low frequency of the composites at 80 C over that of the neat resin. However, at higher frequencies, the difference between the neat resin and the composites' shear modulus was less than that at low frequencies. The complex viscosity of the composite increased upon the addition of CaCO 3 . However, the shear sensitivities of the neat resin and the microcomposite were similar.

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