Abstract: A primary piston is described of molded plastic and equipped with a functional metallic insert and at least one groove. The primary piston is installed in a master cylinder comprising at least the primary piston and a secondary piston, these being mounted in the bore hole of a master cylinder. These pistons can create pressure in a primary pressure chamber and a secondary pressure chamber, respectively, due to the action of a push rod on the primary piston.

Abstract: Master-cylinder seal housed in a groove around a piston has a core connected to three annular and concentric lips. The core rests against a side of the groove and has: a surface provided with an interior edge followed by a peripheral platter cut by at least one channel, and an exterior crown provided with a connection zone formed by an interruption in the crown and deformable due to pressure within the seal to recreate the crown's continuity and impermeability while facilitating purging the brake system when there is no pressure in the channel and the connection zone.

Abstract: “Cup for master cylinder, advantageously a tandem master cylinder, and a tandem master cylinder fitted with such cups” The cup for a master cylinder coming into contact with its primary piston or its secondary piston and subjected to the pressure of the brake fluid of the primary chamber and of the secondary chamber. The cup (60) has two large grooves (622, 624) bordered: by a rib (627) between the heel (621) and the first groove (622), by a rib (623) between the first groove (622) and the second groove (624), by a rib (625) between the second groove (624) and the small grooves (626), these ribs (627, 623, 625) being in protrusion (DS) relative to the cylindrical surface (D) of the heel (621) in the mounted position of the cup (50) in order to separate the heel (620) from the surface of the piston (30) and form, between the heel (620) and the surface of the piston (30), a gap (621) with a film of brake fluid (628). Master cylinder notably a tandem master cylinder fitted with such cups.

Abstract: Methods for producing nanostructured silicon and silicon-germanium via solid state metathesis (SSM). The method of forming nanostructured silicon comprises the steps of combining a stoichiometric mixture of silicon tetraiodide (SiI4) and an alkaline earth metal silicide into a homogeneous powder, and initating the reaction between the silicon tetraiodide (SiI4) with the alkaline earth metal silicide. The method of forming nanostructured silicon-germanium comprises the steps of combining a stoichiometric mixture of silicon tetraiodide (SiI4) and a germanium based precursor into a homogeneous powder, and initiating the reaction between the silicon tetraiodide (SiI4) with the germanium based precursors.

Abstract: A carbamate compound is disclosed.

Abstract: A method for preparing cyclic urea compounds from at least an activated carbamic acid derivative containing an unprotected primary or secondary amine function, includes a cyclization step which consists in a reaction between the primary or secondary amine function and the carbamic acid function of the carbamic acid derivative(s).

Abstract: Process for the preparation of stable activated derivatives of carbamic acid, comprising at least one protected amino group and an activated carbamic acid function, from an amino acid derivative in which the amino group is protected. The process includes: a) a step of transformation of the —COOH group of the amino acid derivative into a —CON3 group to obtain an acyl azide; b) a step of transformation of the —CON3 group of the acyl azide into a —NCO group to obtain an isocyanate; c) a step of treating the isocyanate to obtain a stable derivative of carbamic acid.

Abstract: Process for the preparation of stable activated derivatives of carbamic acid, comprising at least one protected amino group and an activated carbamic acid function, from an amino acid derivative in which the amino group is protected. The process includes: a) a step of transformation of the —COOH group of the amino acid derivative into a —CON3 group to obtain an acyl azide; b) a step of transformation of the —CON3 group of the acyl azide into a —NCO group to obtain an isocyanate; c) a step of treating the isocyanate to obtain a stable derivative of carbamic acid.

Abstract: Process for the preparation of stable activated derivatives of carbamic acid, comprising at least one protected amino group and an activated carbamic acid function, from an amino acid derivative in which the amino group is protected. The process includes: a) a step of transformation of the —COOH group of the amino acid derivative into a —CON3 group to obtain an acyl azide; b) a step of transformation of the —CON3 group of the acyl azide into a —NCO group to obtain an isocyanate; c) a step of treating the isocyanate to obtain a stable derivative of carbamic acid.

Abstract: A method for preparing cyclic urea compounds from at least an activated carbamic acid derivative containing an unprotected primary or secondary amine function, includes a cyclization step which consists in a reaction between the primary or secondary amine function and the carbamic acid function of the carbamic acid derivative(s).

Abstract: Process for the preparation of stable activated derivatives of carbamic acid, comprising at least one protected amino group and an activated carbamic acid function, from an amino acid derivative in which the amino group is protected. The process includes: a) a step of transformation of the —COOH group of the amino acid derivative into a —CON3 group to obtain an acyl azide; b) a step of transformation of the —CON3 group of the acyl azide into a —NCO group to obtain an isocyanate; c) a step of treating the isocyanate to obtain a stable derivative of carbamic acid.