THE SALT CRYSTALLIZATION WEATHERING OF BUILDING ROCKS OF THE ARCHAEOLOGICAL SITES CALCARENITES OF NORTH-WESTERN MOROCCO (LIXUS, BANASA AND THAMUSIDA)

The archeological cities of north-western Morocco: Lixus, Banasa and Thamusida represent an international heritage, with a great social and cultural importance for the history of the country. This work is dedicated to study the salt crystallization weathering, reaching the building rocks of the monuments in order to preserve and restore them. These monuments show a variety of lithological facies implemented in its construction.The degradation of these materials is accelerated by climate influence of El Gharb and Prerif area, characterized by a high humidity and an important atmospheric and soil salinity. The most affected building rocks by the weathering are generally represented by limestones (calcarenites).When salt crystallizes in the pores of the rock after evaporation, the crystal dissociates the grains surrounding by expansion. Therefore, there is a loss of material. The accelerated aging test laboratory shows that calcarenites present the highest rate of weight loss among the samples of different lithologies. This is rendered in a significant susceptibility to degradation; a physical degradation by salt crystals expansion and a chemical degradation by a carbonates dissolution in the presence of the saline fog and a high temperature (50 °C).Lixus calcarenites are more resistant to weathering by salt, when compared to the calcarenites of the other two monuments

Comparison between the noise properties of PtSi/p-Si1-xGex and Pt/p-Si1-xGe Schottky contacts prepared by co-sputtering and thermal reaction

The noise properties of Pt/p-Si1-xGex and PtSi/p-Si1-xGex (x = 0.14) Schottky contacts have been studied. The silicide layer PtSi was formed by thermal reaction (TR) of Pt with a silicon substrate and by co-sputtering (CS) of Pt and Si onto the strained Si1-xGex layer. The noise measurements were performed at temperature T = 77 K over the frequency range 10-10(4) Hz, Higher noise level was observed in the annealed diode Pt/p-Si1-xGex. In both diodes, the noise was found to exhibit l/f behaviour and was attributed to fluctuations of the generation-recombination current at the interface states. The results reveal significant reductions in the total noise by 70%, and the interface state density Ni, by three orders of magnitude when the silicide is formed by the CS process

Mid-IR plasmonics and photomodification with Ag films

The optical properties of semicontinuous silver films have been studied in the mid infrared. The film extinction spectra are shown to be well tailored by the deposition conditions and post-fabrication photomodification with both nanosecond and picosecond laser pulses at 10.6 mu m. The photomodification results in a decrease of the extinction above the laser wavelength. We find that the induced changes in the optical responses of the films are both wavelength and polarization selective. This technique allows the creation of long-pass filters for the mid-IR range in accord with the earlier theory