Abstract: The invention concerns a method for determining the temperature stability of a hydrocarbon mixture capable of phase separation by monitoring the weight variations of a gravimetric sensor part of which is immersed in said mixture. The method consists in: a first step of accelerated cooling of said mixture to a predetermined temperature; and a second step during which said mixture is maintained at this temperature, the time-dependent variation curve of said weight enabling the determination of the resulting solid mass and the separation speed of the two phases by determining the slope of this curve, the stability of said mixture being obtained by comparison with hydrocarbon mixtures of which the stability in time at low temperature between 0 and -30.degree. C. has been controlled.

Abstract: A bifunctional anti-settling and dispersant additive for middle distillates from 150-450.degree. C. petroleum fractions, characterized in that consists of at least one modified copolymer with a weight-average molecular weight of 500-5000 prepared as follows: in a first step, a first carboxylic acid is copolymerized with an alkylated ester of a second carboxylic acid which is the same as or different from the first, and in a second step, the carboxylic groupings of the resulting copolymer re amidified at a temperature of 100-200.degree. C. ##STR1## wherein n and m are from 1 to 8, and R and R' are preferably alkyl groupings.

Abstract: A PIN photodiode having a low leakage current comprises a substrate (10) of indium phosphide (InP) which is n.sup.30 doped and on whose first surface is formed a layer (11) of indium phosphide (InP) which is n.sup.- doped and on which is disposed a MESA structure formed by a layer (b 12) of gallium indium arsenide (InGaAs) which is n.sup.- doped and is moreover constituted by a layer (13, 113, 213) of the p.sup.+ type formed at the surface, at the edges and along the circumference of the MESA structure. The structure further comprises a metallic contact (22) formed on the second surface of the substrate and an ohmic contact (21) formed on a part of the p.sup.+ layer. The invention is characterized in that the n.sup.- doping of the layer of indium phosphide (InP) (11) is chosen to be lower than the n.sup.- doping of the layer of gallium indium arsenide (InGaAs) (12), and in that the ohmic contact (21) is formed on a part (213) of the p.sup.

Abstract: A PIN photodiode having a low leakage current comprises a substrate (10) of indium phosphide (InP) which is n.sup.+ doped and on whose first surface is formed a layer (11) of indium phosphide (InP) which is n.sup.- doped and on which is disposed a MESA structure formed by a layer (12) of gallium indium arsenide (InGaAs) which is n.sup.- doped and is moreover constituted by a layer (13, 113, 213) of the p.sup.+ type formed at the surface, at the edges and along the circumference of the MESA structure. The structure further comprises a metallic contact (22) formed on the second surface of the substrate and an ohmic contact (21) formed on a part of the p.sup.+ layer. The invention is characterized in that the n.sup.- doping of the layer of indium phosphide (InP) (11) is chosen to be lower than the n.sup.- doping of the layer of gallium indium arsenide (InGaAs) (12), and in that the ohmic contact (21) is formed on a part (213) of the p.sup.