Alkali-activated geopolymers based on calcined phosphate sludges and metakaolin.

The extraction of phosphorite ore in Tunisia has resulted in the discharge of substantial amounts of phosphatic sludge into the region's water system. To mitigate this environmental issue and prevent heavy metal leaching, a geopolymerization process was employed using two types of Tunisian calcined phosphate sludges (Cal-PS1 and Cal-PS2) as substitutes for alkali-activated metakaolin. This study aimed to investigate and compare the physical and mechanical properties of the resulting geopolymers.

Gap plasmon modes and plasmon-exciton coupling in a hybrid Au/MoSe/Au tunneling junction.

The light-matter interaction between plasmonic nanocavity modes and excitons at the nanometer scale is here addressed in the scanning tunneling microscope configuration where an MoSe monolayer is located between the tip and the substrate. We investigate by optical excitation the electromagnetic modes of this hybrid Au/MoSe/Au tunneling junction using numerical simulations where electron tunneling and the anisotropic character of the MoSe layer are taken into account. In particular, we pointed out gap plasmon modes and Fano-type plasmon-exciton coupling taking place at the MoSe/Au substrate interface.

Removal of phosphate from synthetic wastewater: A comparative study between both activated clays using an experimental design methodology.

Phosphate-loaded industrial wastewaters have resulted in numerous environmental issues that have hard hit the Gulf of Gabes-Tunisia, making the environmental protection one of the most compelling priorities. Consequently, this study aimed first to compare the amounts of phosphate adsorbed by two types of Tunisian activated clays. The second goal was to assess and optimize the phosphate removal efficiency of these clays, using Box-Behnken design (BBD) under response surface methodology.

GaAs membrane PhC lasers threshold reduction using AlGaAs barriers and improved processing.

Active suspended membranes are an ideal test-bench for experimenting with novel laser geometries and principles. We show that adding thin AlGaAs barrier near the top and bottom Air/GaAs interfaces of the membrane significantly reduces the carriers non-radiative recombinations and decreases the threshold of test photonic crystal test lasers. We review the existing literature on photonic crystal membrane fabrication and propose an overview of the significant defects that can be induced by each fabrication step.