Abstract: A superconductive element is described, comprising a rigid support made of a non-superconductive material, said support comprising at least one superconductive track formed by a groove containing a superconductive material having a density equal to at least 85% of the value of its theoretical density, and the process for producing said element. The present invention also relates to the possible uses of the superconductive elements, and also to superconductive devices comprising said superconductive elements.

Abstract: A superconductive element is described, comprising a rigid support made of a non-superconductive material, said support comprising at least one superconductive track formed by a groove containing a superconductive material having a density equal to at least 85% of the value of its theoretical density, and the process for producing said element. The present invention also relates to the possible uses of the superconductive elements, and also to superconductive devices comprising said superconductive elements.

Abstract: A process is described for the preparation of magnesium borohydride having a high purity and crystallinity, which comprises the reaction of an orgenometallic compound of magnesium of the type MgX2, wherein X is an organic binder selected from alkyl, amide, alkoxide, cyclopentadienyl, aryl, with a derivative of a boron hydride, in a hydrocarbon solvent.

Abstract: A method is described for the preparation of superconductor massive bodies of MgB2, having a density close to the theorical value, which comprises the following passages: mechanical activation of crystalline boron with the formation of activated powders; formation of a porous preform of said powders; assembly of the porous boron preform and massive precursors of metallic magnesium in a container and sealing thereof in an atmosphere of inert gas or with a low oxygen content; thermal treatment of the boron and magnesium as assembled above, at a temperature higher than 700° C. for a time greater than 30 minutes, with the consequent percolation of the magnesium, in liquid phase, through the activated crystalline boron powders.

Abstract: A process is described for the preparation of magnesium borohydride having a high purity and crystallinity, which comprises the reaction of an orgenometallic compound of magnesium of the type MgX2, wherein X is an organic binder selected from alkyl, amide, alkoxide, cyclopentadienyl, aryl, with a derivative of a boron hydride, in a hydrocarbon solvent.

Abstract: There are provided herein a superconductive composite tape and a method of fabrication thereof: a tape having a layer made of superconductive material positioned on a substrate is etched, for example by using laser equipment, in order to obtain a plurality of grooves through the superconductive material layer and delimit a plurality of superconductive filaments, which are substantially parallel to one another and to a longitudinal axis of the tape and are spaced out from one another.

Abstract: It is provided a method for making biaxially textured layers on non-textured substrates, in particular for making intermediate buffer layers in superconductive composite tapes. A non-textured substrate is provided with a surface having a roughness of less than approximately 10 nm and preferably less than approximately 5 nm. This is followed by a deposition step, in which a deposition material is deposited on said surface with direct evaporation without any concern for orientation; the deposition material grows in a natural texture on the surface to form an oriented layer with biaxial texture.

Abstract: There are provided herein a method and an apparatus for deposition of films of coating materials on a substrate, of particular use in obtaining superconductive composite tapes for deposition of films of superconductive oxides and/or buffer layers. A step of deposition of the film on the substrate is associated to a step of gas treatment in situ, in which a flow of gas is sent towards a working surface of the substrate or of the film growing on the substrate. The gas-treatment step is performed via ultrasound-expansion nozzles.

Abstract: A method is described for the production of superconductive wires based on hollow filaments made of MgB2, which comprises: a) the formation of a composite billet by means of the coaxial insertion in a tubular metallic container of a cylindrical bar made of metallic magnesium and amorphous boron powder in the interspace between the container and bar, said powder being pressed between the metallic container and the magnesium bar, in such a quantity that the weight ratio magnesium/boron is higher than 1.2; b) at least one plastic deformation treatment of the composite billet thus obtained until a wire with a pre-fixed diameter is obtained, with the subsequent winding of the wire onto a support; c) a thermal treatment of the filament product thus obtained, at a temperature ranging from 700° C. to 950° C. for a time ranging from 15 minutes to three hours.

Abstract: Polymerization catalysts, particularly catalysts for the polymerization of olefins, are disclosed. The catalysts are prepared by mixing(A) an organometallic compound or hydride of a metal belonging to Groups I to III of the Mendelyeev Periodic Table; with(B) the product obtained by contacting (1) an addition product obtained by reacting a di-, tri-, or tetravalent titanium compound with an electron-donor compound, with (2) an anhydrous magnesium halide, in particular anhydrous MgCl.sub.2 or MgBr.sub.2, which is either preactivated or mixed with the Ti compound under conditions which result in its activation; or by contacting (A) with(B') the product obtained by contacting a di-, tri, or tetravalent Ti compound with an electron-donor compound and a support consisting of an anhydrous Mg halide, in particular MgCl.sub.2 or anhydrous MgBr.sub.2, which is either preactivated or mixed with the Ti compound and electron-donor under conditions such that the Mg halide is activated.

Abstract: Polymerization catalysts, more particularly catalysts for the polymerization of ethylene and mixtures thereof with other monomers copolymerizable therewith, are disclosed. The catalysts are prepared by mixing (A) an organometallic compound or hydride of a metal belonging to Groups I, II or III of the Mendelyeev Periodic Table, with (B) the reaction product of (1) a titanium compound of the type (NR.sub.4).sub.p Ti.sub.m X.sub.(n.m)+p, in which R.sub.4 is hydrogen and/or hydrocarbon radicals, X.sub.n.m represents halogen atoms or, in part, OR' groups in which R' is an organic radical; n represents the Ti valence, and m and p are the whole numbers 1, 2 or 3; and (2) a carrier comprising an anhydrous magnesium halide.

Abstract: Polyolefin fibers, which are suited for at least partially substituting the cellulose fibers in the manufacture of paper, are produced by a process which consists in preparing in a pressure vessel a solution of a polyolefin at a temperature higher than the boiling temperature of the solvent under normal conditions, and under autogenous pressure or a pressure greater than the autogenous pressure, in ejecting said solution under the above stated conditions into a zone of lower pressure, in allowing the ejected solution to expand at least partially in said zone, and in then hitting the at least partially expanded solution with a jet of a high-speed fluid, which is at a temperature lower than that of the solution, and has an angled direction with respect to the direction of ejection of the solution.

Abstract: Polymerization catalysts, particularly catalysts for the polymerization of olefins, are disclosed. The catalysts are prepared by mixing(A) an organometallic compound or hydride of a metal belonging to Groups I to III of the Mendelyeev Periodic Table; with(B) the product obtained by contacting (1) an addition product obtained by reacting a di-, tri-, or tetravalent titanium compound with an electron-donor compound, with (2) an anhydrous magnesium halide, in particular anhydrous MgCl.sub.2 or MgBr.sub.2, which is either preactivated or mixed with the Ti compound under conditions which result in its activation; or by contacting (A) with(B') the product obtained by contacting a di-, tri-, or tetravalent Ti compound with an electron-donor compound and a support consisting of an anhydrous Mg halide, in particular MgCl.sub.2 or anhydrous MgBr.sub.2, which is either preactivated or mixed with the Ti compound and electron-donor under conditions such that the Mg halide is activated.

Abstract: Polymerization catalysts, particularly catalysts for the polymerization of olefins, are disclosed. The catalysts are prepared by mixing hydrides of organometallic compounds of metals belonging to Groups I to III of the Mendelyeev Periodic Table with products obtained by contacting (1) titanium compounds of the formulaMpTi.sub.m X.sub.(n. m) +pin which M is an alkaline metal or the group NR.sub.4 in which the valences of the quaternary nitrogen atom are satisfied by hydrogen and/or by hydrocarbon groups or is part of a heterocyclic ring; X.sub.n. m substituents are NR.sub.2 group in which the Rs represent hydrogen, and/or hydrocarbon groups or, in part, halogen atoms; n is the titanium valence; m is a whole number from 1 to 3 inclusive; and p is zero or a whole number from 1 to 3, inclusive; with (2) carriers consisting of anhydrous Mg halides which are in active form or converted to active form by the conditions under which the carriers are contacted with the titanium compounds.

Abstract: Catalysts useful in the polymerization of olefins, more particularly of ethylene and mixtures thereof with alpha-olefins and/or diolefins, are disclosed. The new catalysts are obtained by mixing a halide of titanium or vanadium in which the metal has a valency lower than 4, with a support comprising an anhydrous magnesium or zinc halide in an active form under particular conditions, and then activating the resulting product with a hydride or organometallic compound of a metal belonging to Groups I to III, inclusive, of the Mendelyeev Periodic System.

Abstract: Catalysts useful in the polymerization of olefins, more particularly of ethylene and mixtures thereof with higher alpha-olefins and/or diolefins, are disclosed. The new catalysts are obtained by mixing a hydride or organometallic compound of a metal belonging to Groups I to III of the Mendelyeev Periodic System with the product obtained by contacting a titanium tetrahalide with a support comprising an anhydrous magnesium or zinc halide in an active form, under particular conditions.

Abstract: There is disclosed a process for the stereoregular polymerization of alpha-olefins or mixtures thereof with ethylene, conducted in the presence of highly active and stereospecific new catalysts. The catalysts are obtained from the reaction of a particular Al-alkyl compound which is at least in part in the form of a complex and/or a substitution reaction product with an ester of an oxygenated organic or inorganic acid, with a supported component characterized by having surface area exceeding certain values or showing a particular X-rays spectrum, and obtained by contacting a Ti halogenated compound, preferably in the form of a complex with an electron-donor compound, with a support comprising a Mg or Mn bihalide in an activated condition. In the catalysts the ratio between the Ti compound, expressed in Ti g-atoms, and the g moles of the ester and the electron-donor compound, when present, is lower than 0.3.

Abstract: New, highly active catalysts for the polymerization of ethylene and mixtures of ethylene with higher alpha-olefins and/or diolefins, are disclosed. The catalysts are prepared by mixing (a) hydrides or organometallic compounds of metals belonging to Groups I, II or III of the Mendelyeev Periodic Table with (b) the products obtained by contacting titanium compounds with activated anhydrous halides of magnesium or manganese, diluted with anhydrous compounds of metals belonging to Groups III or IV of said Periodic Table, and which are different from either (a) or the titanium compound of (b).

Abstract: Catalysts useful in the polymerization of olefins, more particularly of ethylene and mixtures thereof with higher alpha-olefins and/or diolefins, are disclosed. The new catalysts are obtained by mixing a hydride or organometallic compound of a metal belonging to Groups I to III of the Mendelyeev Periodic System with the product obtained by contacting a titanium tetrahalide with a support comprising an anhydrous magnesium or zinc halide in an active form, under particular conditions.

Abstract: New, highly active catalysts for the polymerization of ethylene and mixtures of ethylene with higher alpha-olefins and/or diolefins, are disclosed. The catalysts are prepared by mixing (a) hydrides or organometallic compounds of metals belonging to Groups I, II or III of the Mendelycev Periodic Table with (b) the products obtained by contacting titanium compounds with activated anhydrous halides of magnesium or manganese, diluted with anhydrous compounds of metals belonging to Group III or IV of said Periodic Table, and which are different from either (a) or the titanium compound of (b).