Abstract: A laser device with one or more active regions, such as quantum wells, gain/lighting media, or other devices, and one or more non-absorbing regions, may be formed by a first growth run (growing a first semiconductor layer), then performing selective, shallow-depth etching, and then a second growth run (growing a second semiconductor layer). The laser device may include a first portion, one or more active regions located on the first portion, and a second portion located on the active region(s). A third portion may be located on one or more ends of the first portion and on the second portion. The third portion may be formed during the second growth run, after the etching step. The non-absorbing region(s) may be formed by the third portion and the end(s) of the first portion. If desired, the non-absorbing region(s) may be produced without annealing or locally-induced quantum well intermixing.

Abstract: A laser device with one or more active regions, such as quantum wells, gain/lighting media, or other devices, and one or more non-absorbing regions, may be formed by a first growth run (growing a first semiconductor layer), then performing selective, shallow-depth etching, and then a second growth run (growing a second semiconductor layer). The laser device may include a first portion, one or more active regions located on the first portion, and a second portion located on the active region(s). A third portion may be located on one or more ends of the first portion and on the second portion. The third portion may be formed during the second growth run, after the etching step. The non-absorbing region(s) may be formed by the third portion and the end(s) of the first portion. If desired, the non-absorbing region(s) may be produced without annealing or locally-induced quantum well intermixing.

Abstract: A laser device with one or more active regions, such as quantum wells, gain/lighting media, or other devices, and one or more non-absorbing regions, may be formed by a first growth run (growing a first semiconductor layer), then performing selective, shallow-depth etching, and then a second growth run (growing a second semiconductor layer). The laser device may include a first portion, one or more active regions located on the first portion, and a second portion located on the active region(s). A third portion may be located on one or more ends of the first portion and on the second portion. The third portion may be formed during the second growth run, after the etching step. The non-absorbing region(s) may be formed by the third portion and the end(s) of the first portion. If desired, the non-absorbing region(s) may be produced without annealing or locally-induced quantum well intermixing.

Abstract: The aim of the invention is to identify and provide a substance that influences the protein concentration of animal organisms as well as to provide preparations based on said substance for use in food for animals and humans. Said aim is achieved by using tartronic acid or the derivatives thereof. The invention thus relates to the use of tartronic acid or the derivatives thereof for producing preparations that are suitable for increasing the protein concentration of animal organisms. Also disclosed is the use of preparations containing tartronic acid or the derivatives thereof in animal fodder or food for humans.

Abstract: The invention relates to a method of controlling a hydrogenation of a starting material in a hydrogenation reactor, in which the amount of hydrogen reacted in the hydrogenation is firstly determined, the ratio of the amount of hydrogen reacted to the amount of starting material fed in is then derived, this ratio is compared with a prescribed value and, finally, at least one process parameter is altered if the ratio of the amount of hydrogen reacted to the amount of starting material fed in deviates by a prescribed amount from the prescribed value.

Abstract: Catalyst in the form of an extrudate which comprises from 5 to 85% by weight of copper oxide and in which the same oxidic support material is present in the active composition and as binder, and the use of the catalyst for the hydrogenation of carbonyl compounds.

Abstract: The present invention provides a process for distillatively purifying tetrahydrofuran in the presence of a polar solvent.

Abstract: The present invention relates to a process for preparing optically active hydroxy-, alkoxy-, amino-, alkyl-, aryl- or chlorine-substituted alcohols or hydroxy carboxylic acids having from 3 to 25 carbon atoms or their acid derivatives or cyclization products by hydrogenating the correspondingly substituted optically active mono- or dicarboxylic acids or their acid derivatives in the presence of a catalyst whose active component comprises a noble metal selected from the group of the metals Pt, Pd, Rh, Ir, Ag, Au and at least one further element selected from the group of the elements: Sn, Ge, Mo, W, Ti, Zr, V, Mn, Fe, Co, Ni, Cu, Zn, Ga, In, Pb, Bi, Cr, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.

Abstract: The present invention provides a process for variably preparing mixtures of optionally alkyl-substituted BDO, GBL and THF by two-stage hydrogenation in the gas phase of C4 dicarboxylic acids and/or derivatives thereof, which comprises a) in a first step in the gas phase, hydrogenating a gas stream of C4 dicarboxylic acids and/or derivatives thereof over a catalyst at a pressure of from 2 to 100 bar and a temperature of from 200° C. to 300° C.

Abstract: The present invention relates to a process for preparing optically active hydroxy-, alkoxy-, amino-, alkyl-, aryl- or chlorine-substituted alcohols or hydroxy carboxylic acids having from 3 to 25 carbon atoms or their acid derivatives or cyclization products by hydrogenating the correspondingly substituted optically active mono- or dicarboxylic acids or their acid derivatives in the presence of a catalyst whose active component consists of rhenium or of rhenium and comprises at least one further element having an atomic number of from 22 to 83, with the provisos that a. the at least one further element having an atomic number of from 22 to 83 is not ruthenium and b.

Abstract: The invention relates to a catalyst provided in the form of an extrudate, which contains 5 to 85% by weight of copper oxide and comprises, in the active material and as binders, the same oxidic carrier material. The invention also relates to the use of the catalyst for hydrogenating carbonyl compounds.

Abstract: A multi-zone jacketed pipe reactor (2; 60; 90; 130) for carrying out exothermic gaseous phase reactions and with at least one reaction zone (I) working with vaporisation cooling, at least one reaction zone (II) working with circulation cooling and, possibly, with additional zones (III, IV) is characterised in that one reaction zone (I) working with vaporisation cooling forms the first reaction zone to which is connected an additional reaction zone (II) working with circulation cooling. In this way there occurs at the beginning of the reaction, when the latter is most violent, very intensive cooling at a precisely controllable temperature and especially as well a temperature that is constant across the entire cross-section of the reactor while subsequently in a subsequent reaction zone working with circulating cooling by means of global counter-flow guidance of the heat transfer agent a constant cooling of the reaction gas is achieved.

Abstract: The present invention relates to a process for preparing optionally alkyl-substituted 1,4-butanediol by two-stage catalytic hydrogenation in the gas phase of C4-dicarboxylic acids and/or of derivatives thereof having the following steps: a) introducing a gas stream of a C4-dicarboxylic acid or of a derivative thereof at from 200 to 300° C. and from 2 to 60 bar into a first reactor and catalytically hydrogenating it in the gas phase to a product which contains mainly optionally alkyl-substituted ?-butyrolactone; b) removing succinic anhydride from the product obtained in step a), preferably to a residual level of from <about 0.3 to 0.2% by weight; c) introducing the product stream obtained in step b) into a second reactor at a temperature of from 150° C. to 240° C.

Abstract: The invention relates to a catalyst containing from 0.1 to 20 mass % rhenium and 0.05 to 10 mass % platinum in relation to the total mass thereof. The inventive method for producing a support for said catalyst consists in a) treating a support which can be eventually pre-treated with the aid of a solution of rhenium compound, b) drying and annealing said support at a temperature ranging from 80 to 600° C., and c) impregnating the support with a solution of platinum compound and in drying it. The inventive method for producing alcohol by catalytic hydrogenation of carbonyl compound on said catalyst is also disclosed.

Abstract: The present invention relates to a process for preparing optionally alkyl-substituted 1,4-butanediol by two-stage catalytic hydrogenation in the gas phase of C4-dicarboxylic acids and/or of derivatives thereof having the following steps: a) introducing a gas stream of a C4-dicarboxylic acid or of a derivative thereof at from 200 to 300° C. and from 2 to 60 bar into a first reactor and catalytically hydrogenating it to a product which contains mainly optionally alkyl-substituted 7-butyrolactone; b) converting the product stream into the liquid phase; c) introducing the product stream obtained in this way into a second reactor at a temperature of from 100° C. to 240° C.

Abstract: The present invention provides a process for distillatively purifying crude water-containing tetrahydrofuran by passing the crude tetrahydrofuran through three distillation columns, withdrawing water from the bottom of the first column, recycling water-containing tetrahydrofuran from the top of the second column into the first column, passing a sidestream of the first column into the second column, recycling the bottom product of the third column into the first column, and withdrawing a distillate at the top of the first column, which comprises passing a sidestream of the second column into the third column and recovering the pure tetrahydrofuran as the top product of the third column.

Abstract: The present invention relates to a process for preparing unsubstituted or C1-C4-alkyl-substituted gamma-butyrolactone by catalytic hydrogenation of maleic acid and/or its derivatives in the presence of chromium-free catalyst comprising from 10 to 80% by weight of copper oxide and from 10 to 90% by weight of at least one catalyst support selected from the group consisting of silicon dioxide, titanium dioxide, hafnium dioxide, magnesium silicate, activated carbon, silicon carbide, zirconium dioxide and alpha-aluminum oxide.

Abstract: The present invention relates to a process for preparing optionally alkyl-substituted 1,4-butanediol by two-stage catalytic hydrogenation in the gas phase of C4-dicarboxylic acids and/or of derivatives thereof having the following steps: a) introducing a gas stream of a C4-dicarboxylic acid or of a derivative thereof at from 200 to 300° C. and from 10 to 100 bar into a first reactor or into a first reaction zone of a reactor and catalytically hydrogenating it in the gas phase to a product which contains mainly optionally alkyl-substituted y-butyrolactone; b) introducing the product stream obtained in this way into a second reactor or into a second reaction zone of a reactor at a temperature of from 140° C to 260° C.

Abstract: A process for coproducing alkyl-substituted or unsubstituted THF and pyrrolidones by catalytically hydrogenating C4-dicarboxylic acids and/or derivatives thereof in the gas phase in the presence of copper catalysts and reacting GBL with ammonia or primary amines to give pyrrolidones comprises a) hydrogenating C4-dicarboxylic acids and/or derivatives thereof in the gas phase at from 200 to 300° C., from 0.1 to 100 bar, catalyst hourly space velocities of from 0.

Abstract: A base station is provided in a radio communication system by which first communication connections and second communication connections are transmitted. A first radio network controller is provided, by which the first communication connections are transmitted and also a second radio network controller, by which the second communication connections are transmitted. The base station comprises a common high frequency component which processes signals for the first communication connections and signals for the second communication connections. The signals of the first communication connections and the second communication connections are transmitted across an air gap at different carrier frequencies and can be sent by different carriers.