Abstract: The present invention relates to novel compounds of the formula I, methods for their preparation and their use for treatment of diseases. The invention discloses the synthesis of levodopa (L-DOPA) esters by coupling polyhydroxy compounds or their derivatives to the L-DOPA carboxyl group. The synthesis allows to produce L-DOPA derivatives which are highly soluble in water as well as aqueous and biocompatible liquids and have an improved hydrolytic stability in water or aqueous and biocompatible media for an application over several days. The invention helps producing L-DOPA substances for applications in the fields of medicine, biology and medical engineering as well as in the pharmaceutical industry.

Abstract: The present invention relates to novel compounds of the formula I, methods for their preparation and their use for treatment of diseases. The invention discloses the synthesis of levodopa (L-DOPA) esters by coupling polyhydroxy compounds or their derivatives to the L-DOPA carboxyl group. The synthesis allows to produce L-DOPA derivatives which are highly soluble in water as well as aqueous and biocompatible liquids and have an improved hydrolytic stability in water or aqueous and biocompatible media for an application over several days. The invention helps producing L-DOPA substances for applications in the fields of medicine, biology and medical engineering as well as in the pharmaceutical industry.

Abstract: Process for producing a line of weakness in a cover element comprising at least one slit. This slit is produced through a plurality of machining cycles in which a pulsed laser beam is guided in each instance over the cover element along an imaginary line so that the energy of the laser pulses is introduced into the cover element. The slits are produced in two segments. More energy is introduced over the machining cycles in the first, comparatively short segments than in the second, comparatively long segments. The residual wall below the slits decreases with each machining cycle until the first residual wall segment thickness in the first segment is so small that energy portions transmit through the first residual wall segment and are detected by a sensor arrangement arranged downstream. Accordingly, the first residual wall segment thickness is detected, and inferences can be drawn from this about the second residual wall segment thickness.

Abstract: Method for introducing a line of weakness through removal of material at a fibrous covering material, in particular a natural leather, in which a pulsed laser beam is guided a plurality of times over the back side in a line-shaped manner, wherein only one laser pulse is emitted for each impingement point, and the laser pulse causes an input of energy which leads to a heating of the fibrous covering material at the impingement point to a temperature above an ablation threshold and which maintains the temperature below a limit temperature in regions of the covering material adjoining the impingement point.

Abstract: Process for producing a line of weakness in a cover element comprising at least one slit. This slit is produced through a plurality of machining cycles in which a pulsed laser beam is guided in each instance over the cover element along an imaginary line so that the energy of the laser pulses is introduced into the cover element. The slits are produced in two segments. More energy is introduced over the machining cycles in the first, comparatively short segments than in the second, comparatively long segments. The residual wall below the slits decreases with each machining cycle until the first residual wall segment thickness in the first segment is so small that energy portions transmit through the first residual wall segment and are detected by a sensor arrangement arranged downstream. Accordingly, the first residual wall segment thickness is detected, and inferences can be drawn from this about the second residual wall segment thickness.

Abstract: The invention is directed to an apparatus and a method for generating separating fissures in a substrate through action of a laser beam having an elliptical beam cross section with a beam spot length in a movement direction along a separating fissure to be generated in the substrate. The apparatus and method are particularly suitable for separating fissures which start or end on the substrate surface. A suitable diaphragm prevents radiation from impinging on the substrate before the start and after the end of the fissure.

Abstract: The invention is directed to an apparatus and a method for generating separating fissures in a substrate through action of a laser beam having an elliptical beam cross section with a beam spot length in a movement direction along a separating fissure to be generated in the substrate. The apparatus and method are particularly suitable for separating fissures which start or end on the substrate surface. A suitable diaphragm prevents radiation from impinging on the substrate before the start and after the end of the fissure.

Abstract: The invention is directed to a method for generating optically perceptible laser-induced cracks in brittle material, wherein a laser beam, followed by a coolant jet, is guided relative to the surface of the brittle material in order to advance a crack trail into the material starting from an initial crack, and wherein a marking agent which penetrates into the crack during the formation of the crack so as to make the latter visible is mixed with the coolant.

Abstract: The invention is directed to a method for generating optically perceptible laser-induced cracks in brittle material, wherein a laser beam, followed by a coolant jet, is guided relative to the surface of the brittle material in order to advance a crack trail into the material starting from an initial crack, and wherein a marking agent which penetrates into the crack during the formation of the crack so as to make the latter visible is mixed with the coolant.

Abstract: A method and apparatus for trimming the edges of a float glass ribbon whose thickness can vary between 0.4 mm and 24 mm in which a specific depth crack is generated for the respective thickness. The depth of the crack is actively influenced by energy introduced by means of a laser which is controlled as a function of the surface temperature of the float glass ribbon and by a subsequent cooling whose acting period is variable. To ensure a permanently reliable process, the severing crack and the thickness of the float glass ribbon are detected in order to initiate a new initial crack immediately in the event that the severing crack should break up and so that a cutting unit comprising the scribing device, the beam-shaping optics and the cooling nozzles is always at a constant vertical distance from the surface of the float glass ribbon. The method and apparatus are distinguished particularly by the fact that only a low laser power is required.

Abstract: Flat workpieces of brittle material be severed in a time-saving manner by an arrangement according to the invention by inducing thermomechanical stresses by laser radiation, particularly along severing lines in the same orientation in alternating directions, in that the arrangement has two coolant nozzles which selectively direct coolant to the workpiece and which, preferably coupled with optical means for shaping the laser beams, are mounted so as to be rotatable around the axis of the laser head.

Abstract: Flat workpieces of brittle material be severed in a time-saving manner by an arrangement according to the invention by inducing thermomechanical stresses by laser radiation particularly along severing lines in the same orientation in alternating directions, in that the arrangement has two coolant nozzles which selectively direct coolant to the workpiece and which, preferably coupled with optical means for shaping the laser beams, are mounted so as to be rotatable around the axis of the laser head.

Abstract: The invention is directed to a beam-shaping unit for generating a beam bundle which is focused in a punctiform manner, propagates in a ring shape, and has a radiationless central area, comprising a focusing lens, a first axicon and a second axicon, and to an arrangement with a beam-shaping unit of this kind for introducing radiation energy into a workpiece comprising weakly absorbent material which is arranged between a first resonator mirror and a second resonator mirror. The first resonator mirror which is arranged in front of the workpiece in the radiating direction is located in the radiationless central area. The radiation energy can be absorbed to the maximum extent by repeatedly passing through the same interaction volume in the workpiece.

Abstract: The invention is directed to a method for splitting a flat ceramic workpiece through provocation of a separation crack due to stresses occurring as a result of temporal and local application of heat by means of laser along a desired splitting line and, following this, a temporal and local removal of heat by means of a coolant, wherein the beam spot length is calculated from the following formula l=8×d×24/WLF, where l is the length of the beam spot, WLF is the thermal conductivity of the ceramic to be split, and d is the thickness of the ceramic to be split, so that the length of the beam spot generated on the workpiece by the laser is selected depending upon the thermal conductivity of the ceramic and upon the thickness of the workpiece. Particularly with workpieces with high internal stress, process parameters such as the laser power or the forward feed speed are changed over the course of the process in order to influence the magnitude of the induced thermal stresses.

Abstract: The invention is directed to a beam-shaping unit for generating a beam bundle which is focused in a punctiform manner, propagates in a ring shape, and has a radiationless central area, comprising a focusing lens, a first axicon and a second axicon, and to an arrangement with a beam-shaping unit of this kind for introducing radiation energy into a workpiece comprising weakly absorbent material which is arranged between a first resonator mirror and a second resonator mirror. The first resonator mirror which is arranged in front of the workpiece in the radiating direction is located in the radiationless central area. The radiation energy can be absorbed to the maximum extent by repeatedly passing through the same interaction volume in the workpiece.

Abstract: A device for welding a plurality of thermoplastic plastic parts (parts to be joined) forming a hollow body with an opening by a laser, comprising a vacuum holder having a vacuum chamber which communicates with a vacuum pump, is open on one side and, together with the hollow body, forms a closed chamber that can be evacuated. When a vacuum is applied, the vacuum holder holds the hollow body stationary, holds the joined parts together and enables testing of the tightness of the weld.

Abstract: The invention relates to microcapsules for which the walls comprise reaction products of polyisocyanates, guanidine compounds, and optionally amines, wherein the polyisocyanates have an isocyanurate content of at least 30% by weight, based on polyisocyanate, and the walls comprise on average less than 9% by weight, based on the total weight of the microcapsule.

Abstract: A method for working a parting agent layer applied to a substrate material, in which the parting agent layer is acted upon by the radiation energy of a TEA CO2 laser, so that the parting agent layer is heated at least partly to above the destruction temperature of the parting agent and the parting agent therefore loses its parting properties. The substrate material can be particularly a glass forming a vehicle window or a glass powder coat or rubber applied to a window.

Abstract: The invention relates to microcapsules for which the walls comprise reaction products of polyisocyanates with guanidine compounds and amines.

Abstract: A device for welding a plurality of thermoplastic plastic parts (parts to be joined) forming a hollow body with an opening by a laser, comprising a vacuum holder having a vacuum chamber which communicates with a vacuum pump, is open on one side and, together with the hollow body, forms a closed chamber that can be evacuated. When a vacuum is applied, the vacuum holder holds the hollow body stationary, holds the joined parts together and enables testing of the tightness of the weld.