Abstract: A method of estimating an asymmetrical scatter signal distribution wherein asymmetry is introduced by angular incidence of radiation, which has been emitted from a source and transmitted through an object to be imaged, on a detector, is disclosed. This method includes, in an embodiment, modifying scatter that would be derived wherein the radiation is directly incident on the detector with zero degrees of inclination, using an asymmetry factor which indicates the shape and magnitude of the scatter signal distribution and which varies with an angle at which the radiation is incident on the detector, a mean attenuation coefficient of the object, and a distance the radiation has traveled through the object. The estimated scatter provides for correction of scatter in a image.

Abstract: A collimator for X-ray apparatus has an aperture defined by the edges of four movable flexible shutters. Each shutter can be moved independently of the other shutters; thus, the position and the size of the aperture can be adjusted at will. The shutters are moved by winding them onto drums; each drum is driven by a stepping motor. Springs bias the shutters towards the closed position of the collimator.

Abstract: A mammography apparatus has an examination arm with a radiation delivery head and an image receiver. The examination arm is mounted for iso-centric rotation in a plane. A support for the arm and a support column on which the support is mounted allow the height of this plane to be adjusted. Patients can be examined in the standing, leaning, sitting or laying position while in each case maintaining the axis of rotation of the examination arm on the axis of the (compressed) breast to be examined.

Abstract: An improved process to enhance polyurethane foam performance is described. Polyurethane foam is prepared by reactions between a polyisocyanate and an active hydrogen-containing component wherein said reactions are conducted in the presence of catalysts composed of (a) at least one specific tertiary amine carbamate (formed by the reaction of reactive tertiary amine and polyisocyanate) and, optionally, (b) salts formed by the reaction between the specific tertiary amine carbamate(s) and hydroxy- and/or halo-carboxylic acids. The specific tertiary amine carbamates in the subject invention are dimethylaminoethoxyethyl carbamate, bis(dimethylaminopropyl)amino-2-propyl carbamate, dimethylaminoethyl carbamate, and mixtures thereof.

Abstract: The regions of interest of images of both breasts of a patient are defined as regions of the image of minimal surface area and containing views of the breasts. These regions of interest are aligned for simultaneous display of the images. The display now allows simple and direct comparison of the images of both breasts, notably allowing immediate comparison of structural disorganizations within the two breasts.

Abstract: A beam filtering device comprises a strip carrying at least one filter. The strip is wound onto drums between which the strip extends. A rotary drive mechanism drives the drums in rotation to cause the strip to advance and wind onto one drum while unwinding from the other. Advancing the strip makes it possible to arrange one of the filters on the strip in the space between the drums. This allows radiation filtering characteristics to be readily and rapidly modified.

Abstract: A process for preparing a polyurethane foam, especially according to the one-shot foaming process, the quasi-prepolymer process and the prepolymer process by reactions between a polyisocyanate and an active hydrogen-containing component including water and an organic polyol wherein said reactions are conducted in the presence of a reaction product formed by reaction between a tertiary amine and a carboxylic acid having halo functionality and optional hydroxyl functionality.

Abstract: An improved process to enhance polyurethane foam performance is described. Polyurethane foam is prepared by reactions between a polyisocyanate and a polyfunctional isocyanate-reactive component wherein said reactions are conducted in the presence of catalysts composed of (a) a specific reactive tertiary amine compound selected from the group consisting of bis(dimethylaminopropyl)amino-2-propanol, bis(dimethylaminopropyl)amine, dimethylaminopropyldipropanolamine, bis(dimethylamino)-2-propanol, N,N,N′-trimethyl-N′-hydroxyethyl-bis(aminoethyl)ether and mixtures thereof; and (b) at least one carboxylic acid salt of the specific reactive tertiary amine compound selected from the group consisting of hydroxy-carboxylic acid salts and halo-carboxylic acid salts.

Abstract: The invention provides a fire retardant composition comprising a dispersion of a solid fire retardant such as melamine, ammonium polyphosphate or guanidine carbonate in a liquid organic polyisocyanate which contains dispersed polymer particles. The preferred content of solid fire retardant is from 10 to 100% by weight and the preferred content of polymer particles is from 2 to 30% by weight. The compositions of the invention are suitable for the preparation of flexible and rigid polyurethane foams.

Abstract: A method for the preparation of flexible polymeric foam by reacting a polyisocyanate component with an isocyanate-reactive component comprising at least 50% by weight of water, the polyisocyanate component comprising at least two polyisocyanate compositions, one of them being a low NCO isocyanate terminated prepolymer and the second being a high NCO polyisocyanate.

Abstract: A method for the preparation of flexible polymeric foam by reacting a polyisocyanate component with an isocyanate-reactive component comprising at least 50% by weight of water, the polyisocyanate component comprising at least two polyisocyanate compositions, one of them being a low NCO isocyanate terminated prepolymer and the second being a high NCO polyisocyanate.

Abstract: Process for preparing a flexible foam by reacting an isocyanate prepolymer having a free NCO content of 2-15% by weight, an isocyanate prepolymer having a free content of 25-31% by weight and an isocyanate-reactive composition comprising water.

Abstract: A continuous process for the preparation of an isocyanate-terminated prepolymer having an NCO content in the range from 2 to 15% by weight, said process comprising the steps of:(A) continuously delivering to a reaction zone an organic polyisocyanate composition and an isocyanate reactive compound having an average molecular weight of at least 1000 the relative proportions of isocyanate composition and isocyanate reactive compound being appropriate for the formation of a prepolymer having an NCO content in the indicated range;(B) allowing the isocyanate composition and the isocyanate reactive compound to react in the reaction zone to form an isocyanate-terminated prepolymer, and(C) continuously removing the prepolymer from the reaction zone.

Abstract: Process for preparing a flexible foam by reacting an isocyanate prepolymer having a free NCO content of 2-15% by weight, an isocyanate prepolymer having a free content of 25-31% by weight and an isocyanate-reactive composition comprising water.

Abstract: The invention provides a process for the manufacture of polymeric foams by reacting at least one isocyanate-containing component and water, in which process the isocyanate-containing component comprises a dispersion of a solid fire retardant additive in a liquid isocyanate prepolymer having a free NCO content between 2 and 15% by weight.The invention also provides new fire retardant compositions comprising a dispersion of a solid fire retardant in liquid isocyanate-containing prepolymer compositions based on a diphenylmethane diisocyanate component and a polyol component.

Abstract: The invention relates to a liquid isocyanate-containing prepolymer composition having an average isocyanate functionality greater than 2 and an NCO content of from 2 to 15% by weight, as obtainable by reacting an isocyanate reactive polymer having an average nominal functionality of from 2 to 6 with a stoichiometric excess of a diphenylmethane diisocyanate composition containing at least 2% by weight of 2,4'-diphenylmethane diisocyanate and having an average isocyanate functionality in the range from 2 to 2.3. The invention also relates to a method for preparing a polyurethane foam, which comprises reacting such a prepolymer composition with water.

Abstract: Substantially water blown flexible polyurethane foams, based on methylene diphenyl isocyanates, having a density ranging from 15-45 kg/m.sup.3. Such foams may be obtained through a process substantially avoiding halocarbon blowing agents, which comprises reacting methylene diphenyl isocyanates with water and one or more isocyanate-reactive compounds selected from polyols and polyamines with a functionality of 2-4 and an average equivalent weight ranging from 750-5000, while the isocyanate index ranges from 10 to 60, and weight ratio of the isocyanate-reactive compound(s) to water is less than 20.

Abstract: Flexible polyurethane foam based on methylene diphenyl isocyanates and isocyanate-reactive compounds selected from polyols and polyamines, for which the ratio of the density expressed in kg/m.sup.3 to the compression hardness at 40% compression, expressed in kPa, has a value of at least 20.Such foams may be obtained through a process which comprises reacting methylene diphenyl isocyanates with one or more isocyanate-reactive compounds selected from polyols and polyamines with a functionality of 2-4 and an average equivalent weight ranging from 750-5000 and from 0 to 5 parts by weight of water per 100 parts of polyols and/or polyamine, optionally together with additives conventional in the art, and optionally together with blowing agents other than water, whereas the isocyanate index ranges from 10 to 60.

Abstract: Substantially water blown flexible polyurethane foams, based on methylene diphenyl isocyanates, having a density ranging from 15-45 kg/m.sup.3.Such foams may be obtained through a process substantially avoiding halocarbon blowing agents, which comprises reacting methylene diphenyl isocyanates with water and one or more isocyanate-reactive compounds selected from polyols and polyamines with a functionality of 2-4 and an average equivalent weight ranging from 750-5000, while the isocyanate index ranges from 10 to 60, and weight ratio of the isocyanate-reactive compound(s) to water is less than 20.

Abstract: A magnetic field is produced by way of an emitter placed close to the surface of a product to be controlled and a receiver separate from the emitter is placed, with respect to said emitter, on the one hand, in such a way as to be aligned with the emitter in a direction corresponding to the general orientation of the defects to be detected on the surface of the product, and on the other hand, so as to avoid any substantial direct influence from the eddy currents generated by the emitter when the product surface is defect-free, so that a significant signal is only picked up by the receiver in the case of a deviation of said eddy currents in its direction due to a discontinuity in the surface of the product. The invention finds an application in the detection of surface defects in semi-finished metallurgical products and in particular continuously cast steel products.