We have prepared a cadmiocalcium OH Ap by heating the equimolar mixture of cadmium carbonate and apatitic tricalcium orthophosphate at different temperatures. Then the mixture was analysed by X-Ray, IR and TGA. Results showed that the structure and stability of the obtained cadminocalcium OH Ap depend on the preparation atmosphere.
M. Farhat, A. Hamad, S. Chemlal
Pages 49-56
We have studied the collisional Rayleigh and Raman intensity for densities between 18 and 130 Amagat at 293 K. The depolarisation ratios have been compared to those calculated with dipole-induced dipole model taking into account the anisotropy of molecules. The agreement between theory and experience is rather good for low densities.
H. Khalfallah, R. Boukhris, A. Gharbi
Pages 57-64
A band E microwave measurement device has been set up and tested. The ferroelectric-paraelectric phase transition of a KH2PO4 monocristal has been observed at a temperature of 123 K for a frequency of 70 GHz. The extreme values of complex permittivity during the transition have been determined.
H. Zangar, M.S. Haouat
Pages 65-67
Claisen rearrangement of 1,4-diaryloxy 2-butynes in the presence of protonic acid yields first derivates of benzofuro (3,2-b) benzofuran. These products could be transformed to their isomers: derivates of benzofuro (2,3-b) benzofuran by an acidic catalysed shift. A mechanism is proposed for this reaction.
M. Rammah, B. Laude
Pages 3-13
Four compounds were isolated for the first time from the seeds of Lepidium sativum (cruciferae) with alkaloids extraction method: The ethyl-sinapinate 1. the N-N' dibenzylthiourea 2, the N-N' dibenzylurea 3 and a novel compound which we called the lepidine 4. Their structure has been established by spectroscopic means.
A. Bahroun, M. Damak
Pages 15-24
Dehydroascorbic acid reduction by thiols is carried out using classical and differential polarography. Electrochemical behaviours of reagents: ascorbic, dehydroascorbic, glutathione. British Anti Lewisite, are examinated, also the analytical advantages of this method.
C. Regnault Roger
Pages 25-32
The selectivity coefficient kAl/H relating to the fixation of aluminum ions on a sulfonic resin Duolite C20 is determined in nitric medium. Exchange kinetic in the resin column is expressed by the height of transfer unit.
M. Feki, H. Ayedi
Pages 33-40
After a recall on the principle of on absorption heat pump and a review of a test unit (power: 1 kw) operating with the couple LiBr-H2O, the authors present absorption heat pump performance. The results show that :
- Exchanger area is a limitant factor of exchange
- The performance of absorber increases with solution flow rate and decreases with the increase of concentration
- The experimental COP is less then theoretical COP
- The level of up-grading 140° from industrial heat recovery (60-80°C) is possible with a COP about 1,4.
S. Gabsi, R. Bugarel
Pages 41-49