Abstract: Process for the treatment of a material comprising a polymer, especially a polyamide. The process consists in subjecting the polyamide to hydrolysis in the presence of a hydrolyzing nitrous grouping and transforming the hydrolyzed compounds into diacids. The treatment of a polyamide 6.6 results in the recovery of adipic acid and other diacids corresponding to the participating acid monomer and to the transformation of at least one part of the diamine monomer into diacids.

Abstract: Cementation slurries well suited for encasing reinforcing elements therefor, for example prestressed steel cable, while reducing the risk of embrittlement thereof, contain from about 1.5% to 3% by weight of homogenizing and exudation-reducing hydrophilic particulates (e.g., precipitated silica particles) that are inert in respect of liquids, have a specific surface area of greater than about 200 m.sup.2 /g and which are fragmentable during mixing and/or injection into multiple fragments having particle sizes ranging from about 5 to 300 nanometers.

Abstract: A reactor comprises a cylindrical body (1) with a lower cylindrical portion (5) and an upper cylindrical portion (6) of greater diameter than the lower portion, mutually connected by a connecting ring (7), a filtering ring (2) arranged in the lower part of the upper portion (6) and supported by the connecting ring (7), and an inner cylindrical member (3) having, at the lower end thereof, a flange (8) bearing on the filtering ring (7) and providing a gap (9) between the outer periphery of the flange (8) and the inner wall of the upper portion (6), wherein all the rotary elements are coaxially disposed.

Abstract: A process for spraying concrete or mortar, by a dry route or by a wet route, in order to produce on a surface a layer of concrete or of mortar. Just before or at the time of spraying, an aqueous suspension (A) of silica and of an aluminum compound chosen from aluminum sulphate, basic aluminum sulphates, alums and mixtures thereof is added to the concrete or mortar. The aqueous suspension (A) has a pH lower than 4, a solids content of between 10 and 50% by weight, and, after a period at rest of 48 hours, is in the form of a gel which is reversible under low shear. The aqueous suspension (A) is effective for increasing the thickness of the sprayed layer and reducing rebound of the concrete or mortar sprayed onto the surface.

Abstract: Liquid vanillin compositions, well suited as flavoring/perfuming agents for a wide variety of applications, for example in human and animal foodstuffs, cosmetics and perfumes, comprise (a) vanillin, (b) ethylvanillin and (c) an aqueous and/or organic solvent therefor.

Abstract: Ceric oxide particulates having a specific surface of at least 190 m.sup.2 /g, measured after calcination at a temperature of from 350.degree. to 450.degree. C., and a specific surface of at least 15 m.sup.2 /g after calcination at 800.degree. C., are prepared by (a) suspending, in an aqueous solution of a decomposable base, a ceric hydroxide of the formula (I):Ce(M).sub.x (OH).sub.y (NO.sub.3).sub.z (I)wherein M is an alkali metal or a quaternary ammonium radical; x is a number ranging from 0.01 to 0.2; y is such that y=4-z+x; and z is a number ranging from 0.4 to 0.7; (b) heating the resulting suspension in a confined reaction zone to a temperature and pressure respectively lower than its critical temperature and pressure; (c) cooling such reaction medium and permitting it to return to atmospheric pressure; (d) separating the ceric hydroxide thus treated; and (e) calcining the separated ceric hydroxide.

Abstract: Alkaline-earth metal- and copper- and optionally titanium-based silicates in the form of agglomerates consisting either of monocrystalline grains or of aggregates themselves consisting of monocrystalline particles.These silicates are prepared by a process including the following stages: a silica sol or a silicate and optionally a titanium sol is mixed with salts of the other constituent elements of the silicate with the exception of oxygen; the mixture thus obtained is dried, preferably by spraying, and the product obtained is calcined. The silicates may be employed as colored pigments in plastics, paints, varnishes, rubbers, ceramics, glazes, papers, inks, cosmetic products, dyes and laminated coatings.

Abstract: Thermally stable/highly reducible catalyst compositions, well suited for the catalytic conversion of exhaust gases emanating from internal combustion engines notably vehicular exhaust gases, comprise alumina, the oxides of cerium praseodymium and zirconium, and, optionally, at least one other oxide of bismuth, of a rare earth, or of an element of group VIII of the Periodic Table, and exhibit a stabilized hydrogen-absorption capacity up to a temperature of at least 1,000.degree. C.

Abstract: Novel silicas in the form of powder and spherical beads or granules. The silicas are characterized by having a specific CTAB surface of 100-140 m.sup.2 /g, a small median diameter, following disaggregation by ultrasound means, and optionally, a porous distribution so that the porous volume occupied by the pores whose diameter is 175-275 .ANG. is less than 55% of the porous volume occupied by the pores having diameters of 400 .ANG. or less. The invention also concerns a method for the preparation of said silicas and their use as reinforcing fillers for elastomers.

Abstract: The invention relates to a new process for the preparation of precipitated silica which has a very good dispersibility and very satisfactory reinforcing properties. It also relates to new precipitated silicas which are in the form of powder, of substantially spherical beads or of granules, these silicas being characterized by the fact that they have a CTAB specific surface of between 100 and 240 m.sup.2 /g, a DOP oil uptake lower than 300 ml/100 g, a pore distribution such that the pore volume consisting of the pores whose diameter is between 175 and 275 .ANG. represents less than 50% of the pore volume consisting of the pores of diameters which are smaller than or equal to 400 .ANG., a median diameter, after disintegration with ultrasound, smaller than 5 .mu.m and an aluminium content of at least 0.35% by weight. The invention also relates to the use of the said silicas as reinforcing fillers for elastomers.

Abstract: Oxygen-rich exhaust gases, for example those emanating from internal combustion engines, e.g., diesel engines, are catalytically treated/converted to reduce emissions of NO.sub.x, in the presence of a catalytically effective amount of a spinel mass oxide essentially having the formula ZnAl.sub.2 O.sub.4 which was prepared by forming a solution or suspension of the salts of the constituent elements of the mass oxide, drying by atomizing the solution or suspension and calcining the salts of the constituent elements of the mass oxide so as to result in the spinel mass oxide.

Abstract: Catalyst compounds comprising at least one transition metal in an oxidation state of 0 to 1, and at least one monodentate or bidentate water-soluble phosphine, well suited for the hydrocyanation of ethylenically unsaturated compounds, are electrochemically synthesized, by electrolyzing an aqueous solution catholyte (contained in the cathode compartment of any suitable electrolytic cell) comprising at least one transition metal compound and at least one monodentate or bidentate water-soluble phosphine, advantageously at least one phosphine having the following formulae (I) and/or (II):P(Ar1).sub.a (Ar2).sub.b (Ar3).sub.c (D1).sub.d (D2).sub.e (D3).sub.f(I)(Ar1).sub.a (Ar2).sub.b (D1).sub.d (D2).sub.e P-L-P(Ar1).sub.g (Ar2).sub.h (D1).sub.i (D2).sub.j (II).

Abstract: Environmentally-polluting nitrocresol values are removed from admixtures of nitroaromatic compounds comprised thereof, notably the media of nitration of aromatic compounds by reacting same with aqueous HNO.sub.3 /H.sub.2 SO.sub.4, by first intimately contacting such nitroaromatic compound admixtures with an oxidizing agent comprising hydrogen peroxide, javelle water, or mixture thereof, and thereafter with a neutralizing agent; the nitroaromatic aromatic compounds thus purified are conveniently catalytically hydrogenated into aromatic amines.

Abstract: The present invention relates to a water-redispersible powder based on film-forming polymers which are substantially water-insoluble and which are prepared by aqueous emulsion polymerization of monomers containing ethylenic unsaturation with a "core/shell" structure comprising a hydrophobic core based on a polymer exhibiting a Tg (glass transition temperature) of between -30.degree. and +25.degree. C., preferably between -10.degree. and +20.degree. C., and a hydrophilic shell based on a polymer exhibiting a Tg higher than +55.degree. C., preferably higher than +90.degree. C., characterized in that the shell is bonded to the core by covalent bonds resulting from the reaction of an agent for grafting the shell onto the ethylenic unsaturations remaining in the core, and is substantially insoluble in an alkaline medium.

Abstract: .alpha.-Amino-substituted acetic acids or acid salts of formula ##STR1## where R represents a hydrogen atom or an alkyl or alkoxy group X represents a hydrogen atom, an alkali metal or alkaline-earth metal or an ammonium residue characterized in that they are totally free of haloacetic acid and alkali metal halide. They are capable of being obtained by reaction, under hot conditions, of glyoxal, or of a precursor of glyoxal, with a secondary amine or one of its salts of formula ##STR2## where R represents a hydrogen atom or an alkyl or alkoxy group, optionally followed by hydrolysis. They may be used as amphoteric surface-active agents for the manufacture of cosmetic compositions.

Abstract: The present invention relates to a process for the preparation of carboxylic acids from unsaturated fatty acids and/or their derivatives.The process of the invention is characterized in that it comprises the following stages:a stage which consists in oxidizing an unsaturated fatty acid in the form of acid and/or of ester using hydrogen peroxide, in the presence of a metal oxide or of a carboxylic acid optionally used in combination with a ruthenium-based catalyst,a stage which consists in reacting the reaction mixture originating from the preceding stage with nitric acid in the presence of a vanadium-based catalyst, optionally used in combination with a cocatalyst, and thena stage of recovery of the mono- and dicarboxylic acids.It is particularly well suited for the preparation of saturated mono- and dicarboxylic acids obtained from unsaturated fatty acids such as oleic acid or from oils and fats.

Abstract: The present invention relates to an aqueous silicone dispersion, capable of being cross-linked into an elastomer by removing water and optionally alcohol and/or carboxylic acid, said dispersion being based on at least one polyorganosiloxane (A) having at least two condensable or hydrolysable OR.sup.a groups per molecule wherein R.sup.a =H or alkyl, as well as at least one surficant (B). The technical problem consisting of perfecting a stable dispersion capable of being cross-linked into an elastomer that is highly adhesive on any support and that has suitable and economic mechanical properties is solved since this dispersion includes an amino-functionalised polyorganosiloxane (C) of the DTT(N)(OMe) resin type redistributed with aminoethylaminopropyltrimethoxysilane, optionally at least one hydroxylated and/or alkoxylated silicone resin (D), optionally at least on alkoxysilane (E) donating the -OR.sup.

Abstract: The invention relates to a reagent which is useful for the synthesis of oxysulphide-containing fluorine-containing organic derivatives by reacting with an oxide of sulphur, especially sulphur dioxide, characterized in that it comprises:a) a fluorocarboxylic acid of formula E.sub.w --CF.sub.2 --COOH where E.sub.w is an electron-withdrawing group or atom which is at least partially salified by an organic or inorganic cation, andb) an aprotic polar solvent; andin that the content of releasable protons carried by its various components, including their impurities, is at most equal to half the initial molar concentration of the said fluorocarboxylic acid.This reagent can be used by heating in order to form fluorine-containing sulphinic or sulphonic acids.

Abstract: An agent for recovering heavy metal cations from an aqueous effluent, including a silicate or aluminosilicate type compound, e.g. an alkali metal silicate or aluminosilicate, and a carbonate type compound, e.g. an alkali metal carbonate, and preferably a carrier such as a lay. The agent may also form a cation stabilizer. Said agent is useful for removing or stabilizing heavy metal cations in the water used for cleaning flue gases from waste incineration, particularly household refuse and industrial waste incineration.

Abstract: The invention relates to a gel made of apolar medium including:an apolar medium,a "multichain" liquid surface-active agent in acidic form, soluble or dispersible in the said apolar medium,an agent for neutralizing the said "multichain" surface-active agent,from 0.2 to 5 molecules of water per molecule of "multichain" surface-active agent,optionally at least one emulsifying agent and/or a solid filler which is soluble or insoluble in the apolar medium.This gel may be employed for the formulation of water-based drilling fluids.